Scientific activity of Jacky Cosson
Former Research director in CNRS (France)
Presently Professor in South Bohemia University (Czech Rep.)
Email : [email protected]
I have been part of the research group called UMR 7009 CNRS (Biology of Development) led successively by Christian Sardet, then by Chritian Gache and then after by Evelyne Houliston in the Marine Station of Villefranche sur mer (University P & M Curie/ Sorbonne Univ. - France) where I settled myself in 1981. Previously, I was initially trained to research at the Center for Molecular Genetics, CNRS Gif sur Yvette, France (1969-77) as a biophysist and a biochemist. This period was followed by a post-doctoral stay for 2 years aux USA, one in University of Hawaii and second in Columbia University, New York USA in 1977 -78. The various collaborations that I have established with many foreign laboratories mean that my current research activities are also located in many other laboratories such as in Canada, USA, Japan, Czech Republic, Iran, Mexico, Spain, China, Norway, Chile for examples.
My major research topics concern the motility, the biogenesis, the regulation of cilia and flagella, that I am studying at the molecular and cellular level and which are present in cell types as diverse as sea urchin sperm, fish, unicells or even ciliated cells of embryos, human lung cells, etc…
Introduction: Cilia are extensions of many eukaryotic cell which are very rich in microtubules responsible for essential functions of motility and detection of extra-cellular signals. In sperm and unicellular eukaryotes, a form of motile cilium called "flagellum" exerts a propelling force that allows the cell to move quickly in the liquid medium through rhythmic movements, while in the epithelial cells or in ciliated protists, it is groups of cilia which, being motile in harmony, are displacing the environing fluid. In the photoreceptors of vertebrate cells or in neuronal mechano-and chemo-receptors of invertebrate, the entire machinery transfers light signals or sensory reception and is housed in a specialized compartment derived from cilia.
The mechanism by which the rhythmic beat of cilia or flagella is generated and maintained remains only partially understood. Given the ubiquity of the structure of any axoneme (that is the structure internal to cilia/flagella and responsible for movement), also considering the enormous range of cells or tissues where cilia / flagella are present and the extraordinary diversity of roles filled by these cilia / flagella, several basic questions raised by these organelles remain open to investigation:
1 - how so specific functions, such as that of motility, can be insured at the molecular level, knowing that associated with the microtubules scaffold, at least 4 to 500 types of polypeptides are entering in the composition of a cilium / flagellum and that they are ubiquitous in the living world;
2 - how to regulate these various functions and what is the role attributed to specific polypeptide in the regulation of each of these functions, such as nutrition or reorientation towards a light source for flagellated unicellular, or swimming behaviour of spermatozoa towards the egg (possibly led by chemotaxis) for fertilization, etc.;
3 - how the assembly of protein components in a cilium / flagellum can be orchestrated during the building of the organelle (ciliogenesis). The understanding in these areas has been progressing very rapidly in the past two decades thanks to the ability to display real-time (videomicroscopy) of the rapid movement of cilia or flagella but also the identification of transport factors and mechanisms used to build a flagellum which led to identification of most of the key molecular motors responsible for transport.
Currently, several sets of important data underlying mechanisms and engines involved are well described: the internal scaffold consists of a cylindrical arrangement of 9 double microtubules at the center of which a pair of single microtubules are localised (so called 9+2 structure). This complex scaffold, coupled with numerous regulatory proteins motors is called "axoneme" and is sufficient to generate the rhythmic movement of a native cilium or flagellum, provided the exogenous supply of energy in the form of ATP.
Figure: See below a quick and simple schematic representation of the internal structure of a flagellum, the axoneme. It is estimated that more than 400 different polypeptides must be assembled to form its functional structure.
My research interest presently and in the recent past (since 20 years) are integrated among the three main themes which are mentioned above:
1 - role played by the molecular components of a flagellum in the function of motility : our results have identified the role of many of the components of a axoneme, which assembly is very complex but self-sufficient for flagellum motility, by using a strategy of selection of monoclonal antibodies targeted to epitopes specifically involved in axonemal motility. Several biological models were used: flagella of unicells (Chlamydomonas, dinoflagellates, trypanosomes) and of sperm of sea urchins, fish, humans, etc.
2 - regulating functions of flagella: This regulation may be categorized as "internal" or "external", meaning either regulation by internal control integrated into the axonème which is sufficient by itself to ensure in the flagellum "any" basic motility (house keeping) or control signals from" external" origin able to provoke a reaction (specific stimuli), such as in unicellular as dinoflagellates which are able to respond to contact or light signals or sperm cells (example = those of fish) capable of responding to ionic signals activating or inactivating motility or to specific chemical signals and able to redirect it towards the egg (chemotaxis among ascidians or siphonophores of macroplancton) .
3 - ciliogenesis that I studied in sea urchins embryos and in other marine animals, using experimental conditions to monitor the regrowth of the cilia in the next hour following deciliation.
Content: this pamphlet aims to describe my contributions to several of the above mentioned areas which have been developped since long in the laboratory of Villefranche and were studied for more than three decades in collaboration with the late Professor Jean Cachon and his wife Monique Cachon (DR CNRS), both specialists of motility in marine protists and also with the late Marie-Paule Cosson (DR CNRS) who brought in the laboratory in the early 80s studies on the regulation of fish sperm flagella, especially those of sea-urchins and fish. Current studies are in part the continuity of these themes and have been conducted for some in collaboration with P. Huitorel from the same laboratory, as well as through collaborations with many other colleague scientists all around the world.
The present pamphlet reviews the contributions that I made in those areas, while I am myself close to the end of my scientific career because of the due date for my retirement. I chose to present this pamphlet mostly using the publication to which I participated during my career at the CNRS, and which shed light and details about the established results, especially in key areas more devoted to applied sciences such as fish aquaculture for example. I hope during these next years to be able pursue my scientific career as a professor/researcher, in order to transfer part of my know-how for future applications of methods that I developed and used on biological materials of aquaculture interest as I have detailed in the last part of this report and that I wish to see applied to a few species where the aquaculture knowledge is less developed such as that of tropical fish or pearl oysters.
Presentation of some topics where I contributed during my career:
1) Understanding of the role of functional components of an axoneme, the engine component of cilia / flagella I have contributed to fundamental studies aiming to understand the role of several regulating components or engines themselves present in axonemes of sperm or cilia. This has been possible mainly through the use of functional demembranated flagella (axonemes devoid of any membrane) combined with the development of many monoclonal antibodies capable of blocking very specifically in vitro individual component of demembranated axonemes (reactivated by the ATP addition), using sea urchin sperm as a model, as well as the cilia/flagella of Chlamydomonas or human sperm.
This is an example of characterization of regulation by internal factors through the development of "anti-movement" monoclonal antibodies targetted to axonemes. By the production and use of monoclonal antibodies, we have developped tools particularly powerful to characterize and specify the function of each protein that could be involved in the flagellar movement or its regulation and which is highly conserved in the course of evolution. This approach by applying monoclonal antibodies is complementary to that practiced by biochemical (selective extraction of components, such as dyneins) or by analysis of the characteristics of motility mutants (in Chlamydomonas) affected in any particular component of the axoneme but which often leads to pleiotropic "paralysis". The antibodies that we develop are, by their mode of selection, targetted towards epitopes involved one way or another in the movement and are much more specific for these studies.
Figure: Below is a brief illustration of the structure of a axoneme, which is ubiquitous in the cilia or flagella of many species (in this example, that of cilium in Chlaydomonas):
Above is an illustration showing the complexity of an axoneme :the number protein subunits component (ranging 4-500) in such high resolution 2D electrophoresis gel: their identification and their definition as component of any substructure inside the axoneme does not solve the question of its precise role inside this axoneme.
Description of the strategy used for selection of "antimovement" Moab : flagella are permeabilized and reactivated by addition of ATP, using sea urchin sperm models (Paracentrotus lividus and Arbacia punctulata), human sperm, primitive dinoflagellates (Oxyrrhis marina) or ciliates different models as cilia embryos of sea urchins, cilia human lung explants or cilia / flagella in Chlamydomonas; cilia or flagella of all these models, in controlled conditions, present characteristics of movement very similar to those observed in vivo, but one way or another, their movement is affected by the presence of some specific antibodies. On the other hand, after appropriate treatment (aside proteolysis), the microtubular doublets are induced to slide relative toeach other provided the presence of ATP (sliding), which leads to the disintegration of the axonème at speeds well defined which allows to direct studies of the "sliding", as this motility is directly dependent on in situ dynein (not extracted), the later being molecular motors responsible for the sliding and thus, consequently, for the genesis of flagellar waves. These sliding tests are also conducted in the presence or not of Moab. As a complement these original Moab are used for cytolocalisation using techniques of immuno-fluorescence and electron microscopy. Finally, these observations are supplemented by techniques of biochemistry: purification of various types of flagella or cilia (preparative centrifugation) and selective extraction of components followed by electrophoretic separation and immuno-blotting. Thus, these permeabilized flagellar models (axonemes) reactivated by ATP are used at first as test for screening of each potent Moab (which in the case positive answer disrupts or blocks the movement) and at second to allow the understanding of its effect on motility (affecting wave amplitude, or wavelength, or asymmetry, or beat frequency, or combination of some of the flagellar waves characteristics).
Properties of some of Moab anti-movement that we have selected
Name | Epitope | Properties | Effect on Motility | Publi |
D1 | Anti-O.A.-Dyneine | similaire à 78kD/IC1 sous-u de Dynéine de Chlamy. | Blocage distal | 36,39 |
B3 | -tubulin, site de polyglutamylation | similaire à GT335 | Décroit amplitude | 56,58 |
D66 | Anti -tubuline | similaire à B3 & GT335 | Décroit fréquence et amplitude | 103 |
C9 | Anti -tubuline / site polyglycylation |
| Décroit fréquence | 70 |
Axo49 | Anti-tubuline / site polyglycylation | similaire à TAP 952 | Affecte trajectoire de la tête | 68 |
control | Anti alpha & eta tubuline | décore l’axonème en Im.Fluor. | Pas d'effet | 58,68 70 |
D316 | Anti - 67 kD | séquence déterminée: 67kD = composant de la tête des ponts radiaires | Induit rotation et affecte nage en 3D | 89 |
D405 | Anti - 33kD | cloné et séquencé; 33 kD similaire à p28 IADyn. de Chlamydomonas | Inhibe à faible concentration | 71 |
L2 & L3 | Anti- radial spoke RS1 et RS2 | Spécifiques de la tête ou le la tige des “radial spokes” | Réduit l’amplitude | 142 |
Each one among the Moab that we produced is "anti-movement" according to our definition, meaning that it disturbs one or several parameters of the movement specially when applied at very low concentrations of antibodies (a few micrograms / ml ); moreover, we showed that the observed effect differs between Moabs ; initially, most selected MoAbs have proven to be IgM,which delicate to handle ; but in a second series of Moab that we rised, some of which recognize proteins never described and different from tubulin or dyneins, are IgG allowing the possibility of using their Fab fragments.
Briefly, we have identified and highlighted the role played by a protein of 33 kDa (not previously identified in sea urchin) in the axonemal movement through the MoAb D405: the sequence of this protein confirms its originality (71). Similarly, D66 (new anti-tubulin Moab) induces spiralisation features on the proximal third of axonemes leading to a partial paralysis and a twist on itself to axoneme (103). The Moab D316 is targetted to an original protein of 95 kDa (radial head bridges) : in the presence of D316, the flagellar waves become three-dimensional spiral (89). The Moab AXO49 affects the flagellum in such a way that the heads trajectories of perméabilisés sea urchin sperm are heavily modified (68).
We also used a variant of the abovementionned screening selection of MoAbs, based not only on the direct interference on the movement parameters but on changes of other parameters such as the symmetry of the beat (known to be regulated by the Calcium ions) and thus allowing to target an other set of proteins not yet identified and involved in the asymmetry of flagellar beat.
We have also developed in collaboration with C. Gagnon and his laboratory at McGill Univ. (Montreal- Canada), the ATP reactivation of perméabilised Chlamydomonas flagella : this unicellular algae have two flagella showing preferentially a ciliary movement which is transiently flagellar ; this unicell offers the possibility to select motility mutants; moreover, these cells can be obtained in large quantities by culturing, thus allowing preparations for biochemical purposes of flagellar protein components purification. several new anti-movement Moab have been erected against Chlamydomonas proteins and showed their ability to inhibit movement of permeabilized / reactivated Chlamydomonas axonemes ; when tested against Chlamydomonas proteins, such Moabs were shown to identify single subunits by immuno transfer. One of them, F5 (IgG), is inhibitor of ciliary axonemes of Chlamydomonas and of sea urchin sperm flagella. Two other Moab, F1 (IgG) and E4 (IgM) have similar characteristics but inhibit axoneme according to different ways as seen after detailed analysis. The MoAb E3G5 seems to be involved in the regulating operation of dyneins by interaction between the bridgehead of radial spokes radial wherethis epitope is located and the DRC (Dynein Regulatory Protein Complex): the gradual blockage leads to limit the zone of the ciliary wave to its portion nearest to body cell. A similar effect was observed at very low concentration of the purified L2H12 Moab (10-20 ng / ml). The latter Moab (L2) and another similar Moab (L3) seem to have their target being located on radial bridges (radial spokes or RS). These bridges are radial components attached to tubule A of each of the 9 doublets on a axonème. They protrude from periphery toward the central pair which consists of two singlet microtubules with which they interact very transiently during the flagellar beat cycle which allows them to transduce information from the internal (central pair) to the peripheral part of the axoneme, more precisely to the dyneins arms, by regulating their alternative activity. Among other features, our study of their sequence shows the importance of two of the protein components of these radial spokes (which include 17 polypeptides in total), one located in the head of these bridges, one in the main arm, both being targets of the Moabs we selected. The analysis by videostrobomicrography as well as computer simulation also shows that when applying very low concentrations of these MoAbs, it is essentially the shape of the flagellar wave that is affected rather than the beat frequency and also this allows to distinguish between these two antibodies (142).
ILLUSTRATION: cilia of Chlamydomonas ; here we use a "uni" strain featuring a single cilium, which facilitates their study in videomicroscopy ; cilia ar permeabilised and reactivated by ATP. Upper Line = control without Moab, bottom line = incubation with 0.01 g / ml of Moab L2 H12 for several minutes. Successive images from left to right every 1 / 60 th of a second. On the right of each series, schemes of ciliary positions during one beat cycle. Cilium length = 5 µm.
This study on the sequences of these proteins was documented by data on their cytolocalisation by immunofluorescence. These two proteins appear to be directly involved in the regulation of flagellar shape of the waves, in response to signals that should allow to better identify phosphorylation of protein sites for which calcium ions are known to be responsible The latter thus control the assymetry of the form of flagellar waves and is used by cells carrying cilia / flagella to redirect their swimming direction.
As seen above, cell strains of Chlamydomonas selected as motility mutants can be used in addition to sea urchin flagella, for screening new monoclonal antibodies, this in order to highlight their role in new forms of regulation of flagellar beat or ciliary.
The use of some Moab characterized above allowed us to identify by immuno-fluorescence in ciliated sea urchin embryos the presence of cytoplasmic dynein (not axonemal), and localized differently depending on the stage in early embryogenesis. The study by cytolocalisation by immuno-fluorescence could be extended through the use of several other Moab targetted to tubulin : the C-terminus epitopes of this protein are specifically responsible of the active interaction with molecular "motors" (see paragraph on the ciliogenesis in sea urchin embryos). Thus, we began mapping the precise area of the tubulin sequence by using this series of MoAbs (100 & 119) targeted to epitopes very closely located in this region of the tubulin sequence, precisely where are located the sites of grafting for polyglycylated and polyglutamylated side chains, in collaboration with several French laboratories (70,68,71). While microtubules tubes seem to be homogeneous along their length as in their periphery, the specific locations of "polygly" or "polyglu" residues could be used along axonemal microtubules as landmarks for different proteins maps to become transiently grafted for correctly operating, which is the case for dyneins arms, so called IDA (internally located) and ODA (100 & 119).
The anti-tubulin recognizing sub-populations of specific tubulin can be used to track these sub-species during spermatogenesis and during embryogenesis (ciliogenesie) early in sea urchin development, for example. In parallel, monoclonal antibodies currently available can be used for electron microscopy studies of flagella (100) and ciliary embryos to pinpoint various axonemal proteins both in the axonemal structure that blastomeres in embryos. Microinjection of anti-axonemal movements (or Fab fragments) in blastomeres eggs and embryos of sea urchins can study the biological effects they produce, among others on the network of microtubules of the spindle mitotic. The antibodies of interest, coupled with a fluorescent marker used to study its intracellular localization in vivo during the cell cycle, embryogenesis and ciliogénèse. On the sea urchin embryo, the role of these post-transcriptional modifications of tubulin during the ciliogénèse (at blastula loosestrife, for example where we know réinduire a statement in a neo-ciliogénése after full déciliation) should prove very instructive.
From this series of results, 14 articles were published :
103*-PDF- The Carboxy-Terminal Sequence 427D-E432 of Beta-Tubulin Plays an Important Function in Axonemal Motility. (1999) Stéphane Audebert, Daniel White, Jacky Cosson, Philippe Huitorel, Bernard Eddé, and Claude Gagnon. Eur. J. Biochem., 261:48-56.
71*-PDF- Identification, Cloning, and Sequence Analysis of a Mr = 30,000 Protein from Sea Urchin Axonemes That Is Important for Sperm Motility.(1996) D.GINGRAS, D.WHITE, J.GARIN, L.MULTINIER, D.JOB, J.COSSON, P.HUITOREL, F.DUMAS AND C.GAGNON J. Biol.Chem. 271(22): 12807-12813.
70*-PDF- The polyglutamylated lateral chain of alpha-tubulin plays a key role in flagellar motility (1996) C.GAGNON, D.WHITE, J.COSSON, P.HUITOREL, B.EDDE, E.DESBRYERES, L.PATURLE-FENECHERE, L.MULTINIER, D.JOB AND C.CIBERT. J. Cell. Sci. 109: 1545-53.
68*-PDF- Axonemal tubulin polyglycylation probed with two monoclonal antibodies: widespread evolutionary distribution, appearance during spermatozoan maturation and possible function in motility (1996) M.H. BRE, V. REDEKER, M. QUIBELL, J. DARMANADEN, C. BRESSAC, J. COSSON, P. HUITOREL, J-M. SCHMITTER, J. ROSSIER, T. JOHNSON, A. ADOUTTE and N. LEVILLIERS, J.Cell Sci. 109: 727-738.
58*-PDF- Inhibition of flagellar beat frequency by a new anti-beta tubulin antibody. (1996) J.COSSON, D. WHITE, P. HUITOREL, B. EDDE, C. CIBERT, S. AUDEBERT & C. GAGNON Cell Mot. & the Cytosk. 35: 100-112.
37*-PDF- The covalent oscillator : a paradigm accounting for wave propagation in cilia and flagella ( 1992) J.COSSON Biol. of the Cell, 76: 319-327.
32*-PDF Les micromoteurs flagellaires , J.COSSON, in "Nanotehnologies et micromachines", O.F.T.A., Masson Ed., pp. 129-141, (1992).
ILLUSTRATION: Below in this figure of a section of an axoneme are shown some of the epitopes identified by the antimouvement anti-bodies that we have developed and each of which has enabled us to understand the function of the polypeptides holding the corresponding epitope.
2) The chemotaxis or how the egg causes the pilot and sperm attraction toward him.
I have devoted a special effort to understand a biological phenomenon so called "sperm chemo-attraction" or guidance to the egg cells of the same species, also known as chemotaxis, using three different biological models : siphonophores, ascidians and oysters.
An example of external regulation of flagellar movement: chemotaxis of sperm towards the egg
Several series of results have enabled us to gain a good understanding of the phenomena involved in chemotaxis: we have documented chemotaxis in the Siphonophores oocytes (14 to 17-141-147-148), in oysters and the scallops as well as in the salps (macroplancton, 77 & 88).
Salps: In salps, the spermatozoon must enter to the body cavity then into cloacal (equivalent to the "oviduct" mammals) then reach the ovary for oocyte fertilization. For the sperm flagellum of salps, this implies that several original features are used, some being known to occur for the sperm of some other species, some being exceptional (77); in the case of salps, the transparency of the animal allows the observation in situ (through the tissues) of the movement of flagella. Our results show that: 1 - spermatozoa propagate three-dimensional waves, like the "hyperactivated" mammalian sperm 2 - the amplitude of these waves is very variable at the same time along a single flagellum 3 - the direction of these waves is reversible, and the direction of propagation of sperm is also invertible, 4 - flagella are presenting foldings with very tight pitch monitoring followed by the redeployment of this long sperm tail (0.2 mm) never described in other species .
Ascidians and siphonophores: In collaboration with the group of Prof. M. Morisawa the Misaki Marine Station (Univ. Tokyo), I developed a study of sperm chemotaxis / egg in oysters and also especially in ascidians. On the Mediterranean and Japanese species of ascidians, we showed that a "substance" emitted by the egg is able to activate the swimming of sperm and lead to the attracted swimming towards the egg. This substance is closely related chemically between these species but we have observed no cross chemotaxis between these two species. During my successive visits to Japan, (most recent was in January 2004), and during the stay of 4 months of Pr. Morisawa in our laboratory in 1999, and later in 2004 as well, we began the purification process and the chemical characterization of these two "attractant » molecules and the development of a model reflecting the process of attraction (141-147-148). It was shown that the activation of sperm from ascidian is under the dependence of cAMP (cyclic AMP), and we are trying to clarify the steps by which cAMP is involved in the chemotactic response via protein phosphorylations (141-147-148) .
The mechanism by which sperm chemotaxis occurs was compared in two species apart, and was applied to the siphonophores vs ascidians models that are best described in this regard so far and that we have studied in detail ; we have also simulated on computers behavior in these two models in order to better understand subtle differences compared to mostly common components in the process of chemotaxis (141-147-148).
FIGURE: Above, this illustration shows how a mathematical model is able to mimic the trajectory directed (successive turns) of sperm, namely that of ascidian, up a gradient of concentration up to the point where is issuing a chemoattractant (peak of highest concentration, located at the egg).
In oysters: The study aims to descibe changes in parameters of sperm motility of bivalves such as scallops or oysters (beat frequency of the flagella, amplitude of flagellar waves, speed of movement or sperm shape trajectories, percentage of motile cells, etc ...) according to conditions surrounding the sperm cells (artificial sea water to determine the role of different ions, the pH, or non-ionic synthetic environments maintaining the osmotic pressure surrounding the sperm) ; this has allowed us to acquire information about their conditions of maturation and initiation of motility (46, 73, 96 & 104). We have shown that such a "maturion" process of sperm is induced by chemical agents capable of acting on the intracellular content in cyclic AMP (cAMP). The dibutyryl-cAMP, theophilline, caffeine or even polyvynil-pyrrolidone can induce a swim velocity 3 to 4 times faster and effective for at least 90% of sperm. In experiments with demembranated and reactivated oyster sperm (in the presence of ATP) we show the direct involvement of cAMP in the process of maturation (73). The link between the cAMP-dependent activation and chemotactic response is currently being studied.
Chemotaxis models also continue to be studied, especially on sperm of ascidians with Prof. M. Morisawa Univ. Tokyo. The study of sperm from oyster is pursued through collaborations with two laboratories of IFREMER, one in French Britainy (Dr. Marc Suquet in Brest) and the other in Tahiti with Dr. Marina Schneider (Univ. of French Polynesia) on the pearl oyster.
These programs have been receiving successive funding ; from IFREMER France several contracts were awarded in 1995 to 99, and a common project of CNRS France / JSPS Japan in 1995-96 and in 1998. I made a new stay in the laboratory of Pr Morisawa in Japan in August 2000, a second in March 2002 and a third at beginning of 2004 and Dr. Morisawa came for a visit in Oct 2004 in our laboratory.
The results on this "chemotaxis" theme led to 6 publications and have also been part of a Ph D thesis (Catherine Faure IFREMER Brest 1992) on the reproduction of the oyster and scallops :
141*-PDF- Strategies for sperm chemotaxis in the siphonophores and ascidians: a numerical simulation study.2004 Makiko Ishikawa, Hidekazu Tsutsui, Jacky Cosson, Yoshitaka Oka and Masaaki Morisawa, Biol. Bull. 206:95-102.
88- Timing of Sperm Shedding and release of Aggregates in the Salp Thalia demecratica (Forskal, 1775) (Urochordata, Thaliacea) R.L. MILLER and J.J. COSSON (1997) Marine Biol. 129:607-614.
ILLUSTRATION: Below is shown the attraction of siphonophore sperm towards a structure localised at the animal pole of the egg, the « cupule » experimentally detached: the traces correspond to the positions of the head of each spermatozoon during 1 / 4 sec. and show that they describe circles precisely centered on the cupule.
3) How fish spermatozoa switch on their swim and why is their period of movement so short? I have greatly contributed to understanding of the mechanisms of activation of sperm in many fish species : indeed, the fish sperm present two main original features : 1) their activation occurs only when getting into contact with the outside environment where they reproduce (either freshwater or marine species) ; 2) the duration of their swim is short, lasting one to few minutes depending on species (see 136-137-140-181 journals and book chapters 115 - 162-163).
Below, the evolution of the form of waves of sperm flagellar turbot as they progress in the period of motility. This illustration shows the rapid decay of swimming ability of sperm of fish (turbot here as an example): comparing photographs from the left (7 seconds after activation by sea water) to the right (4 minutes after activation), we see how the progressive restriction of flagellar waves in the part of the flagellum proximal to the head leads to decrease the swimming performance. Strobomicroscopy usin a black background (so called dark field), flash frequency = 300 Hz, length of the flagellum = 60 µm approx.
An example of external regulation of flagellar movement: the movements of fish sperm
The phase of sperm movement of fish is very brief (a few minutes), but during this period many flagella characterizing sperm parameters (frequency, amplitude and shape of the waves, etc) evolve very quickly: it has been established in numerous publications to which I participated and which relate mainly to the regulation of osmotic and ionic motility of sperm, their energic and their capacity for fertilization or cryopreservation
3a-activation mechanisms of the movement in spermatozoa of Trout, Tench, Carp and silurids
The sperm motility of trout is activated by simple dilution in freshwater : apart from trout, many of our own results tend to exclude cyclic AMP (cAMP) as a secondary messenger in this activation (25-26-38-50-53-76) . On an other hand, we have pursued studies on the role of the creatine phosphate/creatine kinase "shuttle" in the initiation and maintenance of sperm motility trout (76)
The study of the role of cAMP continues through collaboration mentioned above with Prof. M. Morisawa at the Misaki Marine Station in Japan
In carp or tench and other cyprinids, as well as in silurids (catfish) the cAMP is not involved, and in this respect, we have published many results on these species. Especially in carp, we characterized in detail the energy content of sperm (ATP) during the swimming period (55).
In silurids (catfish, Silurus glanis), we have conducted for several years in the 90s several programs aiming to control the artificial condition for propagation of this species.
In carp, we have particularly shown that when sperm is motionless at the end of swimming period, it can become again capable of motility and regain ability to fertilize (171-180)(174).
Specially in carp, all these results have led to more than 16 publications (27-28-45-50-51-55-57-65-75-78-93-112-118-120-152-171)
3b-Spermatozoa of sturgeon and paddle-fish (or fish spatula)
A good control of the conditions for activation of gametes of these species is a necessary step for the development of techniques such as gynogenesis, because when gynogenesis is applied to the sturgeon aquaculture, it provides an opportunity to manage an 100 % Females population, a way to increased profitability and higher production of eggs (caviar). This perspective, as a potentially alternative source of stugeon caviar was applied to another species the "fish spatula » so called paddlefish (Polyodon spathula). This transfer needs to pass through two other key steps: 1) a knowledge of conditions for inactivation of the male genome sperm without affecting their ability to swim and fertilize, 2) a control of the genome duplication of female eggs, for example by using a thermal shock preventing the second polar body to be exported out of the egg. The contribution of previous knowledge acquired in these areas in other species has allowed us to obtain quick results (see 83-117-118-133, for paddle fish and 63-79-82-117-134-153-155- 156-158-160-172-175-178-179 for sturgeon). We also initiated the study of conditions for sperm cryopreservation of these chondrosteans fish taking again advantage from the experience gained in other species in this area (30, 35, 45, 49, 51, 87, 93 , 100, 114, 120, 150 & 157) and we managed to get a very high level of recovery for cryopreserved sperm potentially capable of fertilization in paddle fish and sturgeon as well.
We have also studied the variations of the energy content of sturgeon sperm during its phase of swimming (79). We have also developed specific studies of the regulation of sperm motility by ions in sturgeon and fish spatulas. The potassium ions are particularly active in preventing motility (133), including at very low concentrations (83-109-117). The potassium target seems to be localized inside the axoneme since demembranared / reactivated sperm have their movement very sensitive to potassium ions. In vivo as well as in vitro, inhibitory effect of potassium is antagonistic to that of calcium, the latter being involved in the acrosomal reaction , the acrosome constituting an organelle involved in the anchoring of sperm at the gametes meeting step (13). Acrosome is present in acipencerids such as the sturgeon and spatulas (172-179-183) but is absent in most of all other fish species. The presence of this acrosome almost exclusively in sperm of these fish species (sturgeons) is a topic of particular interest for its biological significance.
Controlling the movement of sperm of paddle-fish and sturgeon also involves studies of the effects of different types of radiation (UV and gamma rays) on the inactivation of the male genome while preserving the axonemal movement. The development of conditions for optimizing the cryopreservation of spermatzoa of these 2 species and the understanding of the role of calcium and potassium ions are continued.
As associated researcher, I have been involved in a tripartite exchange program on the study of gynogenesis in the Paddle-fish which was developed in the Aquaculture Research Center of Kentucky in USA (109,117, 118, 124, 129, 133, 152 & 157) and at the Institute of Fish Culture of the Czech Republic (years 2001-2004) funded by the U.S. Ministry of Agriculture. Another collaboration was also undertaken on this issue also with the University of Tehran and the Institute of Fisheries of Iran (150-153-155-156-158-160) and focuses on improving conditions for artificial reproduction of sturgeons. To this end, I conducted a course of 2 weeks (15-30 April 2002) including the organization of a workshop at the Iranian Fisheries Research Organisation in Rasht, Iran. (134) This collaboration continues with the support of a postdoctoral researcher, H. Alavi. (136-137-138-153-155-158-160-162-163-167-171-172-174-175-176-178-179-180). Another collaboration of more than 16 years with the laboratory of Dr. Linhart in Czech Republic (Univ. South Bohemia) is the subject of fruitful exchanges and numerous publications on the aquaculture of sturgeon and other fish species (45-51-63-82-83-86-90-93-113-117-118-120-124-129-131-132-133-152-157-171-172-174-179-180-183 ). We have also recently developed a technique of non destructive identification of sustainability (fluomicroscopie in vivo) and the ability to sperm motility of fish (129).
3c- marine fish spermatozoa (Sea Bass-Turbot-Cod-Hake-Tuna-Tilapia)
Through our studies on the sperm of different marine fish such as halibut, sea bass and turbot, we have shown that the activation of their swimming is triggered by increasing the external osmotic pressure (OP) which is much higher in sea water relatively to the seminal fluid. This situation is reversed in freshwater fish where the activation takes place when sperm cell face a reduced external OP (see 136-137-140-162-163-181 for review and 83-86 at 53-63-75-81 -- 90-97-100-101-112-115-117-159-165-169-170-177 for results). This variation of OP leads to a rapid decline of intracellular ionic content, which is manifested by dramatic changes in the form of waves, which was reconstituted in vitro by the use of sperm models with flagella devoid of membranes (53-76-60-115-169 -170-177) and reactivated by the addition of ATP.
The study of changes in the energy content (ATP, respiration) during the swimming period of native turbot sperm allowed us to record in the ATP, ADP, phosphocréatine content during the motility period (81-98-102). We have supplemented these data with an original study by NMR protonsanalysis applied to sperm: it showed the appearance during this motility phase of unexpected compounds (eg triméthylamineoxyl) ; this study was followed by detailed studies of NMR phosphorus analysis of sperm (98, with F. Séguin, INSERM U316, CHU Tours France).
In case of sea bass sperm, we have characterized in detail the very short period of swimming (97-101-165) in relation to their energy content (ATP 101) and also detailed the effect of pollutants on the characteristics of their sperm motility (165).
We also extended these studies of sperm motility of marine fish to other species such as cod (159-170-177) or hake (169-177) (see below).
Understanding the role of osmolarity in the control of swim lead us to the case of another fish, Tilapia, which shows an interesting situation: this species is present in natural conditions of osmolarity as diverse as freshwater (deltas river) as compared to hypersaline water (puddles on sandbanks with osmolarity up to twice that of seawater), which poses a problem of adjustment of their sperm cells to extreme salinity conditions. In collaboration with Marc Legendre, IRD (ex-ORSTOM) in Jakarta where I completed 3 missions in the field (Jan & Oct 1999, March 2000) and several other missions in 2005-06 and 07 at IRD (Montpellier, France) we have shown that the OP jump able to activate tilapia sperm is directly dependent on the salinity of the environment where fish have been adapted: the OP will break up for groups of fish previously adapted to freshwater but it is shifted for groups of fish adapted to sea water or even more to hypersaline (176).
Another collaboration with Pr. Kazuo Inaba (Asamushi Marine Station, Japan) has enabled us to understand the role of carbonic anhydrase, present in abundance specifically in the sperm of flat fish (including turbot), all species where precisely CO2 is able to block sperm motility (60, 61, 115 & 123) by a mechanism involving carbonic anhydrase which is specifically abundant in the sperm flagella of all flatfish (123) as emphasized. This prevention of motility by CO2 blocks the initiation of the flagellum motility in the testis where CO2 concentration is high and come on top of the control exerted by the external osmotic pressure (intratesticular) used in most fish species. The internal mechanism of CO2 control which is also present among most flatfish species but not among other fish species, was releted to an intraflagellar ion control (75, 109, 115, 121, 128, 130, 136, 137 & 152) as we have initially shown in turbot (140).
The study of cod sperm (endangered species) has been initiated since 2004-2005 (159-170-177) in collaboration with the group of M. Suquet, IFERMER, Brest France, and the group Pr. Igor Babiak , Bodø University College-Department of Fisheries and Natural Sciences in Norway, where I completed a 2 weeks stay in May 2008.
The study of hake sperm begun since 2005 (169-170) in collaboration with the group of M. Suquet, IFREMER, Brest, France and the group of Anne-Laure Groison, University of Bergen, Norway.
The study of tilapia sperm (species of high aquaculture interest) continues since 1995 (176) in collaboration with the group of M. Legendre, IRD, Montpellier, and H. Alavi in the group of Pr. Linhart (Vodnany, Czech Rep.). The study of sperm tuna has also started in 2005 through a collaboration with the group of Dr. Antonio García Gómez, Instituto Español de Oceanografía, Mazarrón (Murcia) in Spain and that of C. Fauvel of IFREMER Palavas, France, during my stay in July 2005 in Mazarron, Spain as included in the framework of the European project "Reprodot" devoted to the conctrol of the artificial reproduction of tuna.
FIGURE: The above illustration shows 2 tuna sperm activated by transfer to sea water since few seconds (flagellum length of 50 µm). Strobe Light Flashes at 150/ sec on left and 50 Flashes/ sec on right.
We have acquired extensive data on the functional characteristics of tuna sperm conditions allowing or preventing their activation, their ability to cryoconservation etc.
3d- cryopreservation of sperm of fish
I, hence, also participated in several operations to safeguard endangered fish species through the development of methods for their sperm conservation by cryogeny. These studies are as expected heavily relying on the use of techniques for appreciation and measurements the movements characteristics of those sperm.
The results of these studies applied to cryogenic propoerties of fish sperm led to 13 publications:
157- Effects of cryoprotectants and males on motility parameters and fertilizability using paddlefish (Polyodon spathula) frozen-thawed spermatozoa. O. Linhart, S. Mims, B. Gomelsky, L. Cvetkova, J. Cosson, M. Rodina, A. Horvath and B. Urbanyi. (2006) J. Applied Ichtyology 22:389-394.
150*-PDF- Cryopreservation and short-term strorage of sturgeon sperm, a review. Billard R., Cosson J., Noveiri S.B. & Pourkazemi M. (2004) Aquaculture 236 (1-4) : 1-9.
120*-PDF- Cryopreservation of sperm in common carp, Cyprinus carpio: sperm motility and embryonic hatching success. (2000) O. Linhart, J. Cosson, and M. Rodina. Cryobiology 41,241-250.
114*-PDF- Cryopreservation of sperm in marine fish. M. Suquet, C. Dreanno, C. Fauvel, J. Cosson and R. Billard (2000) Aquac. Res.31:231-243.
113*-PDF- Changes in the flagellum morphology of intact and frozen/thawed Siberian sturgeon Acipenser baeri Brandt sperm motility. (2000) R. BILLARD, J. COSSON & O. LINHART. Aquacult. Res., 30:1-5.
93- Cryopreservation of Carp (Cyprinus carpio L.) spermatozoa : the influence of external K+ and Na+ on post-thaw motility; O. LINHART and J. COSSON (1997) Polish Arch. Hydrobiol. 44/1-2: 273-277.
87-PDF- Cryopreservation of Turbot (Scophthalmus maximus) sperm.(1997) DREANNO C., SUQUET M., QUEMENER L., COSSON J., FIERVILLE F., NORMAND Y. & BILLARD R. Theriogenology 48:589-603.
63- Motility & fertilizing capacity of fresh & frozen-thawed spermatozoa in sturgeons (Acipenser baeri & A. Ruthenus) (1996) LUDMILLA I.TSVETKOVA, JACKY COSSON, OTOMAR LINHART & ROLAND BILLARD . J. Appl. Ichthyol. 12: 107-112.
59- Sperm physiology and quality. R.BILLARD, J.COSSON, L.W. CRIM & M.SUQUET (1995). In: Broodstock Management and Egg and Larval Quality, N.R. Bromage and R.J. Roberts Eds. Blackwell Sciences, Ltd., Cambridge, Massachusetts. Pp. 25-52.
51- Long term preservation of European catfish (Silurus glanis L.) and common carp (Cyprinus carpio L.) spermatozoa (1994) LINHART O., LIEMAN P., COSSON J., BILLARD R. & KOLDRAS M. in Gamete & Embryo Storage & Cryopreservation of Aquatic Animals; Billard Ed. (pp 30-33).
45*-PDF Biology of sperm and artificial reproduction in carp (1995) R.BILLARD, J.COSSON, G.PERCHEC & O.LINHART Aquaculture 129: 95-112.
35- Physiology and quality of sperm in fish. BILLARD R., COSSON J., CRIM M. & SUQUET M., (1994) Europ. Aquat. Soc. (Spec. Plubl.) 19: 203-218.
34- Bilan des techniques et problèmes de conservation des produits génitaux et des embryons d'organismes marins. R. BILLARD, C. FAUVEL, M. LOIR, G. MAISSE et J. COSSON, Equinoxe (IFREMER),40: 27-30 (1992).
CONSERVATION PROGRAMS: One of the conservation programs on endangered species which I attended is concerned with the Chinese sturgeon and the local fish spatula, two highly endangered species due to the construction of the large dam on the Yangtze Kiang River. I also recently participated in a European program for the Protection of Mediterranean tuna, endangered by intensive fattening practiced for over 10 years on the case of this species.
I intend to continue these collaborations among different fish of aquaculture interest, aiming at assess the abilities of sperm to motility and the development of conditions for activation and conservation, with the following objectives of improvement of these technologies : -1 artificial insemination from these different fish species, -2 improvement of the systems for collecting sperm, the composition of main solutions used for activation and short term conservation as predicted by their energy content, - 3 define the conditions of cryopreservation of these sperm while trying to preserve their quality (ability for activation and for fertilization of eggs). On Tilapia, our study of adaptation of reproduction conditions to saline environment will continue in cooperation the IRD (Montpellier, France) and extended to studies on other species of interest in aquaculture, such as silurids.
This set of results has been the subject of numerous publications mentioned above species by species, altogether more than 85 publications in several journals including reviews (4) and book chapters (3) and also for several years, the participation in the supervision of doctoral students in several foreign labs (as M. Rodina Rep. Czech, or S. Alavi in Iran and Czech Rep. or F. Abascal in Spain and France).
4d-Conclusions on these studies of sperm of fish
The brevity of the movement of sperm of fish associated with poor control of their synchrony during initiation have for long discouraged many of the cell research trials in the past (115). With control of the conditions of their manipulation, short term movement becomes, instead, a major asset for understanding the mechanisms that control the initiation as well as the cessation of their flagellar movement (90). Because of their accessibility over long periods during the year and their abundant quantity, these sperm have characteristics of both value and are excellent complement to those of sea urchin sperm which are and remain a reference model in this regard.
All the work I participated to shows that the control of sperm motility in fish occurs at several levels:
- Energetic via the intracellular ATP concentration (53-55-76-79-81-98-101-112-115-140-181)
- osmotic via the intracellular ion concentration (75-109-115-121-128-130-132-133-136-137-138-152-153-155-160)
- Ionic , via the specific effect of certain ions (136-137) such as potassium (83-109-124-126) or calcium (26-29-38-53-126)
- Gaseous such as observed for CO2 (84-123)
- Mechanical via the form of the flagellar waves (41-62-76-90-113-115-117-140149-181)
The current review of the work on sperm of different fish allows to discern the future three main research avenues where fish sperm are a material of choice: 1 - maturation of the potentiality for movement, 2 - control of flagellar beat activation by the ATP/ADP, ATP/ CrPhosphate & ATP/cAMP, 3-control of initiation and arrest of the movement of native sperm (ions, osmolarity, CO2, seminal fluid proteins, etc ...) .
Figure above: Diagram showing the results in a model with the different levels of regulation for fish sperm motility: 1) the external osmolarity (trigger swim), 2) the internal energy stores (ATP), 3) internal ionic concentration and 4) CO2 (in flat fish such as turbot).
Consequences in aquaculture: In addition to the impact due to the control of activation (or inactivation) by media compatible with the fertilization, the main applications of these results are mainly involving cryopreservation (114-120-144-150): these techniques and their results allow development of freezing media selected primarily on the basis of their ability to preserve sperm motility at the end of thawing tests, which is much easier and faster than to assess the ability to fertilize. As mentioned above, I myself have participated to some fish sperm cryopreservation programs, in some case in some endangered species (mainly sturgeon) and for which the current solution to their preservation is precisely the storage of their gametes by cryopreservation.
The results of these studies on fish sperm has led to more than 85 publications:
Latest results: Publication of a book and of several review articles
Book: “Fish Spermatology” S.M.H.Alavi, J. Cosson, R. Rafiee and K. Coward Eds (2007), 460 pages.
181- Marine fish spermatozoa : racing ephemeral swimmers. J. Cosson, C. Dreanno, C. Fauvel, A-L. Groison, M. Suquet and R. Billard 2008 Reproduction 136 :277-294.
140- Studying sperm motility in marine fish : an overview on the state of the art. J. Cosson, A.-L. Groison, M. Suquet, C. Fauvel, C. Dreanno and R. Billard (2008) J. Appl. Ichthyol. 24 :460-486.
176- Sperm motility activation in the euryhaline tilapia Sarotherodon melanotheron heudelotii (Dumeril, 1859) acclimatized to fresh, sea or hypersaline waters. Legendre Marc, Cosson Jacky, Alavi S.M. Hadi and Linhart Otomar (2007) Cybium (in press).
177- Changes of atlantic cod (gadus morhua, l.) sperm quality during the spawning period C. Rouxel, M. Suquet, J. Cosson, A. Severe, L. Quemenerand C. Fauvel. (2008) Aquaculture Research (accepted)
175- Roles of extracellular Ca2+ and pH on motility and flagellar waveform parameters in sturgeon spermatozoa. Sayyed Mohammad Hadi ALAVI, Marek RODINA, Jacky COSSON, Martin PSENICKA & Otomar LINHART (2007) Cybium (in press).
174- Physiology and behavior of stripped and testicular sperm in Perca fluviatilis L. 1758. Alavi S. M. Hadi, Rodina Marek, Policar Tomas, Cosson Jacky, Kozak Pavel, Psenicka Martin and Linhart Otomar.(2007) Cybium (in press).
173- Sperm characterisitics and motility in Pangasianodon hypophthalmus (Sauvage, 1878) and Pangasius djambal Bleeker, 1846 (Pangasiidae, Siluriformes). Legendre Marc, Cosson Jacky and Subagja Jojo. (2007) Cybium (in press).
172- Morphology, biochemistry and physiology of chondrostean fish sperm: a comparative study between Siberian sturgeon (Acipenser baerii) and sterlet (Acipenser ruthenus). Psenicka Martin, Alavi S.M. Hadi, Rodina Marek, Cosson Jacky, Nebesarova Jana, Gela David and Linhart Otomar (2007) Cybium (in press)
169- Sperm biological characteristics in European hake (Merluccius merluccius) Groison Anne-Laure, Suquet Marc, Cosson Jacky, Le Coz Jean-René, Jolivet Aurélie and Garren Francois (2007) Cybium (in press)
170- Motility characteristics of spermatozoa in cod (Gadus morhua) and hake (Merluccius merluccius). Cosson Jacky, Groison Anne-Laure, Suquet Marc and Fauvel Christian. (2007) Cybium (in press)
171- After exhaustion by a first round of motility, sperm of common carp (Cyprinus carpio) is able to re-initiate a second motility period and save ability to fertilize eggs. Linhart Otomar, Alavi S.M. Hadi, Rodina Marek, Gela David and Cosson Jacky (2007) Cybium (in press).
167- Semen characteristics in Acipenser persicus in relation to sequential stripping. Alavi, S.M.H., Cosson, J., Kazemi, R., (2006). J. Applied Ichthyology, 22 (Suppl. 1): 400-405.
165-PDF Characterization of sperm motility in European seabass. The effect of heavy metals and physicochemical variables on sperm motility. F.J. Abascal, J. Cosson & C. Fauvel (2007) J. Fish Biol. 70(2) : 509-522.
163- The motility apparatus of fish spermatozoa by Jacky Cosson Book Chapter 9 in “Fish Spermatology” S.M.H.Alavi, J. Cosson, R. Rafiee and K. Coward Eds 2007 pp. 281-316.
162- Methods to analyse the movements of fish spermatozoa and their flagella by Jacky Cosson Book Chapter 2 in “Fish Spermatology” S.M.H.Alavi, J. Cosson, R. Rafiee and K. Coward Eds 2007 pp. 63-101.
160-PDF- Sperm motility and fertilizing ability in the Persian sturgeon Acipenser persicus S. M. H. Alavi and J. Cosson (2005) Aquaculture Research 36:841-850.
159-PDF- Changes in atlantic cod (Gadus morhua) sperm quality with time. M. Suquet , C. Rouxel, J. Cosson, A. Severe, L. Quemener and C. Fauvel (2005) European Aquaculture Society, Special Publication No. 36 (in press).
158- Effect of stripping frequency on composition of seminal plasma and sperm density and motility in the Persian sturgeon Acipenser persicus. S.M.H. Alavi, J. Cosson, M. Karami and B.M. Amiri (2006) J. Applied Ichtyology. In press.
153- Determination of some seminal plasma indices, sperm density and sperm motility in the Persian sturgeon, Acipenser persicus Alavi SMH, Mojazi Amiri B., Cosson J., Karami M., Abdoulhay H.A., Pourkazemi M., Akhoundzadeh M.A Iran J Fisheries Sciences, (2006): 5(2) 1-18.
137*-PDF- Sperm motility in fishes: (II) Effects of ions and osmotic pressure: a reviewSayyed Mohammad Hadi Alavi and Jacky Cosson
Previous results
136*-PDF- Sperm motility in fishes: (I) Effects of temperature and pH: a review. (2005)Sayyed Mohammad Hadi Alavi and Jacky Cosson
133*- Ionic composition and osmolality of paddlefish (Polyodon spathula, Acipenseriformes) seminal fluid (2003) Otomar Linhart, Steve D. Mims, Boris Gomelsky, Anna E.Hiott, William L.Shelton, Jacky Cosson, Marek Rodina, David Gela and Jan Bastl. Aquaculture International 11:357-368.
132*- Urinary bladder, ionic composition of seminal fluid and urine with characterization of sperm motility in tench (Tinca Tinca L.) (2003) Otomar Linhart, Marek Rodina, Jan Bastl and Jacky Cosson. J. Applied Ichtyol. 19:1-5.
129*-PDF The application of image cytometry for viability assessment of dual fluorescent stained spermatozoa of fish. A technical note (2004) Flajhans Martin, Cosson Jacky, Rodina Marek and Linhart Otomar Cell Biol. Intern 28/12:955-959.
130*- The ionic and osmotic factors controlling motility of fish spermatozoa. (2004) Jacky COSSON, Aquaculture International 12:69-85.
131*- Kurokura solution as immobilizing medium for spermatozoa of tench (Tinca tinca L.) (2004) Rodina, M., Cosson, J., Gela D. and Linhart, O. Aquaculture International 12:119-131.
124*- Effects of ions on the motility of fresh and demembranated paddle-fish (Polyodon spathula) spermatozoa. (2002) O. Linhart, J. Cosson, S. Mims, W. Shelton and M. Rodina. Reproduction 124:713-719.
123*-PDF- Control of sperm motility by CO2 and carbonic anhydrase in flatfish. Inaba K., Dreano C. and Cosson J. (2003) Cell Mot. & Cytosk. 55:174-187.
121*-PDF- Effect of ionic strength on the motility of turbot (Psetta maxima) spermatozoa. (1999) C. Dreanno, J. Cosson, M. Suquet, Y. Nagahama and R. Billard. Proceedings of the 6th Int. Symp. on the Reproductive Physiol. of Fish, Bergen. p.256.
118*-PDF- Spermiation of paddlefish (Polyodon spathula) stimulated by injection of LHRH analogue and carp pituitary extract. (2000) O. Linhart, B. Gomelsky, S. Mims, A. Hiott, W. Shelton, J. Cosson and M. Rodina. Aquat. Liv. Res., 13:1-6.
117*-PDF- Analysis of motility parameters from paddlefish (Polyodon spathula) and shovelnose sturgeon (Scaphirhynchus platorynchus) spermatozoa (2000) J. Cosson, O. Linhart, S. Mims, W. Shelton and M. Rodina. J. Fish Biol., 56(6): 1348-1367.
115*-PDF- Regulation of axonemal wave parameters of fish spermatozoa by ionic factors.(1999). J. Cosson, C. Dreanno, R. Billard, M. Suquet and C. Cibert. Book chapter in The Male Gamete: from Basic Knowledge to Clinical Applications. C. Gagnon Ed., Cache River Press (Proceedings of the 8th Int. Symp. on Spermatology, MontrÈal, Canada, August 17-22/1998) pp.161-186.
112*-PDF- Initiation of carp spermatozoa motility and early ATP reduction after milt contamination by urine (1998). G. Perchec-Poupard, C. Paxion, J. Cosson, C. Jeulin, F. Andre and R. Billard. Aquaculture 160:317-328.
102*-PDF- Metabolism of turbot (Scophthalmus maximus) spermatozoa: Relationship between motility, intracellular nucleotid content, mitochondrial respiration. (1999) C. Dreanno, F. Seguin, J. Cosson, M. Suquet, and R. Billard. Mol. Reprod. Dev. 53(2): 230-243.
101*-PDF- Effects of osmolality, morphology and intracellular nucleotid content during the movement of sea bass (Dicentrarchus labrax) spermatozoa. (1999) Catherine Dreanno, Jacky Cosson, Marc Suquet, Germaine Dorange, Christian Fauvel,.Christian Cibert and Roland Billard. J. Reprod. Fertil. 116:113-125.
98*-PDF- H+-NMR and 31P-NMR analysis of energy metabolism of quiescent and motile turbot (Psetta maxima) spermatozoa. (2000) Catherine Dreanno, François Seguin, Jacky Cosson , Marc Suquet and Roland Billard . J. Exp. Zool. 286/5 513-522.
97*-PDF- Characteristics of sperm of captive sea bass (Dicentrarchus labrax L.) in relation to its fertilisation potential. (1999) C. Fauvel, O. Savoye, C. Dreanno, J. Cosson & M. Suquet. J. Fish Biol. 54: 356-369.
95- Influence du maintien en mer des mâles de saumon atlantique (Salmo salar) pendant la période de reproduction sur la qualité du sperme (1998) G. MAISSE, R. BILLARD, J. COSSON, C. LABBE, M. LOIR, F. LeGAC et F. FIERVILLE. Bull Fr. PÍche Piscic. 350: 349-357.
86-PDF- Motility of Silurus glanis spermatozoa in the testicles and in the milt. (1997) BILLARD R., LINHART O. FIERVILLE F. and COSSON J. Polish Arch. Hydrobiol. 44/1-1:115-122.
85- Amélioration de la motilité des spermatozoïdes testiculaires de néomâles de truite commune (Salmo truta) au début de la période de reproduction. (1995) Maisse G., Billard R., André F., Cosson J., Le Gac F. 1995. Aquat. Living. Resour., 8: 191-194.
83- Paddlefish, Polyodon spathula, spermatozoa : Effects of potassium ions and pH on motility(1996) J.COSSON and O.LINHART, Folia Zoologica 45(4):361-370.
82- Motility of Siberian Sturgeon (Acipenser baeri) Spermatozoa (1995) COSSON J., O.LINHART, & R.BILLARD The Sturgeon Quaterly 3: 9-10.
81- Changes in the movement characteristics and ATP content in the sperm of carp and turbot (teleost fishes) (1993) G. PERCHEC, L. CHAUVAUD, M. SUQUET, J. COSSON, F. ANDRE & R. BILLARD - C.R. Acad.Agri. 6: 117-126.
79*-PDF- Motility analysis and energetics of the Siberian sturgeon Acipenser baeri spermatozoa (1999) R. Billard, J. Cosson, F. Fierville, R. Brun, T. Rouault and P. Willot. J.Appl. Ichthyol. 15:199-203.
78*-PDF- Morphological and kinetic changes of carp (Cyprinus carpio) spermatozoa after initiation of motility in distilled water. (1996) PERCHEC G., COSSON MP., COSSON J., JEULIN C. AND BILLARD R. Cell Mot.& the Cytosk. 35:113-120.
76*-PDF- The use of creatine-phosphate plus ADP as energy source for motility of membrane deprived trout spermatozoa. (1998) SAUDRAIS C., FIERVILLE F., CIBERT C., LOIR M., LE RUMEUR E. and COSSON J. Cell Mot. & the Cytosk. 41:91-106.
75- Effects of extracellular environment on the osmotic signal transduction involved in activation of motility of carp spermatozoa. (1997) G. PERCHEC-POUPARD , J-L. GATTI, J. COSSON, C. JEULIN, F. FIERVILLE and R. BILLARD J. Reprod. & Fert. 110:315-327.
69*-PDF- Effect of urine on semen quality in Turbot (Scophthalmus maximus) (1998) DREANNO C., SUQUET M., DESBRUYERES E., COSSON J., LE DELLIOU H and BILLARD R., Aquaculture 169:247-262.
66*-PDF- Artificial insemination in turbot (Scophthalmus maximus) determination of the optimal sperm to egg ratio and time of gamete contact. (1995) M. SUQUET, R. BILLARD, J. COSSON, Y.NORMANT & C. FAUVEL . Aquaculture 133: 83-90.
65*-PDF- Degradation of the quality of carp sperm by urine contamination during stripping. (1995) G.PERCHEC, COSSON J., ANDRE F. and BILLARD R. Aquaculture 129: 133-137.
64*- Sperm features in turbot (Scophthalmus maximus): a comparison with other fresh water and marine fish species (1994) SUQUET M., R. BILLARD, J. COSSON, L. CHAUVAUD, G. DORANGE & C. FAUVEL . Aquat. Liv. Res. 7: 283-294.
63- Motility & fertilizing capacity of fresh & frozen-thawed spermatozoa in sturgeons (Acipenser baeri & A. Ruthenus) (1996) LUDMILLA I.TSVETKOVA, JACKY COSSON, OTOMAR LINHART & ROLAND BILLARD . J.Appl.Ichtyol. 12: 107-112.
62- Sperm motility in turbot (Scophthalmus maximus): initiation of movement and changes with time of swimming characteristics (1995) L. CHAUVAUD, J. COSSON, M. SUQUET & R. BILLARD. Env. Biol. Fish 43: 341-349.
59- Sperm physiology and quality. R.BILLARD, J.COSSON, L.W. CRIM & M.SUQUET (1995). In: Broodstock Management and Egg and Larval Quality, N.R. Bromage and R.J. Roberts Eds. Blackwell Sciences, Ltd., Cambridge, Massachusetts. Pp. 25-52.
57-PDF Reproduction in carp: gametes (1994) J.COSSON & M.WIEGANG Aquaculture 129: 140-141.
55*-PDF- Relationship between sperm ATP content and motility of carp spermatozoa (1995) PERCHEC G., JEULIN C., COSSON J., ANDRE F. & BILLARD R., J.Cell.Sci. 108: 747-753.
53*-PDF- cAMP/ATP-dependence of Movement in intact and demembranated Trout Spermatozoa. (1995) COSSON M-P., COSSON J., ANDRE F. & BILLARD R., Cell Mot. & the Cytosk. 31: 159-176.
49- The quality of sperm and egg in fish : evaluation and determining factors (1993) R.BILLARD, J.COSSON, & M.SUQUET, Europ. Aquac. Soc. Spec.Publ. 19: 203-210.
45*-PDF Biology of sperm and artificial reproduction in carp (1995) R.BILLARD, J.COSSON, G.PERCHEC & O.LINHART Aquaculture 129: 95-112.
35- Physiology and quality of sperm in fish. BILLARD R., COSSON J., CRIM M. & SUQUET M., (1994) Europ. Aquat. Soc. (Spec. Plubl.) 19: 203-218.
30- Motility and Survival of Halibut Sperm During short term storage (1993) R.BILLARD, J.COSSON & L.W.CRIM, Aquat. Living Resour. 6: 67-75.
29*-PDF Synchronous Triggering of Trout Sperm is followed by an Invariable Set Sequence of Movement Parameters Whatever the Incubation Medium (1991) M-P.COSSON, J.COSSON & R.BILLARD Cell Mot. and Cytosk. 20: 55-68.
28*-PDF In vitro Maturation of the Potential for Movement of Carp Spermatozoa. C.REDONDO, M-P. COSSON, J. COSSON & R.BILLARD Mol. Reprod. and Dev. 29: 259-270 (1991).
27- In vitro Incubation and Maturation of Carp Cyprinus carpio Spermatozoa. J. COSSON, R.BILLARD, C.REDONDO-MULLER and M-P. COSSON , Bull.Inst.Zool.,Acad.Sinica, 16: 249-261 (1991)
26- cAMP-dependence of Movement Initiation in intact and demembranated Trout Spermatozoa. COSSON M-P., COSSON J. & BILLARD R., Proc. of the Fourth Int. Symp. on the Reprod. Physiol. of Fish , Norwich U.K., 4: 262-264 (1991)
25- cAMP-dependence of Movement Initiation in intact and demembranated Trout Spermatozoa. COSSON M-P., COSSON J. & BILLARD R. Bull.Inst.Zool.Acad.Sinica, 16: 263-266 (1991).
Most of these topics are subject to ongoing programs and are made in collaboration with many laboratories, mostly abroad: Czech Republic, Poland, Japan, Iran, Chile, Norway, etc.. du'en and France, for example, studying the effects of hypersalinité on the movement of sperm tilapia which is the result of a collabaration with IRD Montpellier (laboratory Marc Legendre) and Institute of 'Rep. aquaculture. Czech (laboratory Otomar Linhart).
4) The variety of movements among unicellular flagellates
I also contributed to the study of flagellar movement among species of flagellated unicells such as trypanosomes and dinoflagellates, species where the flagellar structure (called axonème) is flanked by a parallel structure giving rise to contraction movements of the whole flagellum in dinoflagellates (see 19-20-21-22-24-31-91-122-143 and a review currently being drafted).
FIGURE: Below, electron microscopy of an EM section of a dinoflagellate longitudinal flagellum with 2 adjascent structures and called paraflagellar rod (P), mainly made of associated fibers and axoneme (Ax).
In the case of trypanosomes, the use of "silencing" techniques induced by RNA interference technologies ( so called RNAi) of various genes involved either in the axonemal mechanics or in the PFR (see Para Flagellar Rod 166-168) are a new tool that offers the opportunity to understand the precise function of these genes.
The results of these studies on the flagellated unicells led to about 10 publications:
Recent results
168-PDF- Basal body positioning is controlled by flagellum formation in Trypanosoma brucei. Absalon S., Kohl L., Branche C., Blisnick T., Toutirais G., Rusconi F., Cosson J., Bonhivers M., Robinson D. and Bastin P. (2007). PloSOne e437:1-16.
166-PDF- Conserved and specific functions of axoneme components in trypanosome motility. C. Branche, L. Kohl, G. Toutirais, J. Buisson, J. Cosson & P. Bastin. (2006) J. Cell Sci. 119:3443-55.
Previous results
143*-PDF- Analysis of the contraction of an organelle using its birefringency: the R-fibre of the Ceratium (Dinoflagellate) flagellum (2004) Hidemi SATO, Claude GREUET, Monique CACHON and Jacky COSSON ,Cell Biology International 28-5:387-396.
122*-PDF- Flagellar Movements and Controlling Apparatus in Flagellates. Jacky Cosson , Philippe Huitorel , Laura Barsanti, Patricia L. Walne, and Paolo Gualtieri. (2001) Critical Review in Plant Science 20, 297-308.
91-PDF- Isolation of the major basic nuclear protein and its localization on chromosomes of the dinoflagellate, Oxyrrhis marina. Koichi H.Kato, Akihiko Moriyama, Philippe Huitorel, Jacky Cosson , Monique Cachon & Hidemi Sato (1997) Biol. of the Cell 89:43-52.
31-Analysis of the mechanism of dinoflagellate flagella contraction-relaxation cycle. (1992) M.CACHON, C.GREUET, J.COSSON, &P.HUITOREL. Biol. of the Cell 76: 33-42.
24*PDF- Dinoflagellate flagella adopt various conformations in response to different needs. CACHON M., CACHON J., COSSON J., GREUET C. & HUITOREL P. Biol.of the Cell. 71: 175-182 (1991).
21*-PDF- Ultrastructure of the flagellar apparatus of Oxyrrhis marina CACHON M., CACHON J., HUITOREL P., COSSON J., & COSSON M.P. Biology of the Cell 63: 159-168 (1988).
20*-PDF- Swimming behaviour of the unicellular Oxyrrhis marina : in vivo and in vitro mouvement of the two flagella. COSSON J., COSSON M.P., CACHON J. AND CACHON M. Biology of the Cell 63: 117-126 (1988).
19- The Paraflagellar Rod, a structure in search of a function, CACHON M., CACHON J., COSSON J. & COSSON M.P. Biology of the Cell 63: 169-181 (1988).
Through collaborations initiated with the laboratory of Philippe Bastin (Pasteur Institute, Paris, France) we continue to study variations of trypanosomes swim according to their progress in different tissues of the flies vector, in combination with the use of silencing, induced by RNAi of various genes involved in axonemal mechanics or the paraflagellar structure .
Figure below : Two states of the posterior flagellum of a dinoflagellate either describing propelling waves typical of any flagellum (left) or contracting very sharply in less than 10 milliseconds (second photo). Size of flagellum, approximately 100 µm long.
Other unicellular cells:
Some of my interests are devoted to green algae-type such as Chlamydomonas (see monoclonal antibodies "antimovement" paragraph) and marine unicell algae used in conchyculture of oysters (collaboration with Laboratoire Rene Robert, IFREMER, France) whose swimming parameters are difficult to measure mostly due to the very small size of these cells .
At beginning of my scientific carreer, I have been mostly interested in studies involving yeast : these studies dealt with the structure and function of mitochondrial genes encoding subunits of the mitochondrial ATP synthase, which was the subject of my Ph D and early career and which have led to about a dozen publications:
12- Identity problems concerning subunits of the membrane factor of the mitochondrial ATPase of Saccharomyces cerevisiae; M.Somlo, J.Cosson, L.Clavillier, M.Krupa and I.Laporte, Eur.J.Biochem. 122: 369-374 (1982).
11- Sequence homologies of G+C rich regions of mitochondrial DNA of Saccharomyces cerevisiae. J.Cosson and A.Tzagoloff, -J.Biol.Chem. 254: 42-43 (1979).
10- The use of Aryl-azido-beta-alanyl-ATP as a photoaffinity label for the isolated and membrane-bound mitochondrial ATPase complex. J.J.Cossonand R.J.Guillory -J.Biol.Chem. 254: 2946-2955.(1979).
7-Several classes of binding sites for metals and nucleotides on yeast mitochondrial oligomycin-sensitive ATPase. J.M.Jallon, A.Spirydakis and J.Cosson. Biochimie , 59:869-875 (1977).
6-(Ph D thesis)- Le complexe ATPasique mitochondrial : sa structure et sa fonction chez des mutants oligomycine-résistants du DNA mitochondrial de Saccharomyces cerevisiae. J.COSSON , Thèse de Doctorat d'Etat, Université de Paris-Sud (Orsay) N° 1770, soutenue le 25 Avril 1977.
5-Mitochondrially encoded oligomycin-resistant mutants of Saccharomyces cerevisiae: Structural integration of ATPase and phenotype. M.Somlo, and J.Cosson, Proceeding of the Interdisciplinary Conference on the Genetics and Biogenesis of Chloroplasts and Mitochondria, Th. B¸cher et al. editors, Munich, Germany, August 1976.
4-Translation of mitochondrial RNA from yeast cytoplasmic "petite" mutants in an E.coli cell-free system. A.Halbreich, A.Di Franco, O.Groudinsky, J.Cosson, and P.P.Slonimski. Biochem. Biophys. Res. Commun. 64, 1286-1292 (1975).
3-ADP-thermal reactivation of Triton-inactivated ATPase from mitochondrially determined Oligomycin-resistant mutants of Saccharomyces cerevisiae. J.Cosson and A.Spyridakis, Biochem. Biophys. Res. Commun. 59, 1039-1046, (1974).
116*- Isolation and molecular typing of yeasts in mediterranean waters and marine invertebrates from southern France.(1999) Gautret P., Cosson J.,Kauffmann-Lacroix C., Rodier MH., Charron M. and Jacquemin JL. J. Mycol. Med. 9:162-165.
5) Mechanistic aspects of ciliary motility
I also brought some of my research efforts on understanding the functioning of cilia/flagella including human lung tissue and also cilia of embryonic tissue of the sea urchin.
As already noted, the fundamental mechanisms of the movement that animates the axonemes of flagella are similar to those of cilia. The collaboration with Dr. Claude Meinez-Clary of the Faculty of Medicine of Nice, France since 1990-91 lasted one decade was devoted to the study of bronchial cilia and enabled us to begin to develop perméabilised cilia models that are reactivated by ATP addition; we have shown that their reactivated beating is almost insensitive to the concentration of Ca ions. We have also studied the effect of temperature on the beat frequency of bronchial and nasal human cilia in either native or demembraned (and reactivated by ATP) state (33 & 42). A comparative study of beat frequencies of nasal vs bronchial cilia has also been conducted (74) showing differences in the effect of pH (92 & 99) on the beat frequency. The application of monoclonal antibodies anti-movement (see above) to these explants bronchial demembranated cilia allowed us to explore information (immuno-fluorescence) on various pathologies of these cilia.
The results of these studies on the movement of cilia from human explants origin have led to the 4 following publications:
99- Effect of external pH on ciliary beat frequency (CBF) in human airways. (1997) C. Clary-Meinesz, J. Mouroux, J. Cosson, P. Huitorel, E. Bionne and B. Blaive, Eur.Resp. J. 10:321s.
92- Influence of external pH on ciliary beat frequency in human bronchi and bronchioles.(1998) C.Clary-Meinesz, J.Cosson and P.Huitorel Eur. Resp. J. 11:330-333.
74*-PDF- Ciliary beat frequency in human bronchi and bronchioles (1997) C. CLARY-MEINESZ, J. MOUROUX, P. HUITOREL, J. COSSON, D. Shoevaert & B. BLAIVE. CHEST 111:692-697.
33- Temperature effect on the ciliary beat frequency of human nasal and tracheal ciliated cells (1992) C.F.CLARY, J.COSSON , P.HUITOREL and B.BLAIVE, Biol. of the Cell, 76: 335-338.
6) sperm from other species like scallops or oysters as already mentioned above, as well as those of polychaete, those of salps or those Crepidula consisted mainly in studies focused on best conditions for the activation of male gametes and regulation during the swimming period.
The results obtained from sperm of these various species have led to 5 publications :
104- Gametes as physiological references and parameters of sperm activation in scallop Pecten maximus and japanese oysters Crassostrea gigas (1995) C.Faure, N.Devauchelle N., JP. Girard and J.Cosson, Colloque IFREMER reprod. des Mollusques (Nantes Nov. 95) pp.61-67.
88-Timing of Sperm Shedding and release of Aggregates in the Salp Thalia demecratica (Forskal, 1775) (Urochordata, Thaliacea) R.L. MILLER and J.J. COSSON (1997) Marine Biol. 129:607-614.
80- Intermittent swimming in the spermatozoa of the lugworm Arenicola marina (L.) (Annelida : Polychaeta).(1994) PACEY, A., COSSON, J. & BENTLEY, M.G. . Cell Mot. & Cytoskel. 29: 186-194.
52*-PDF- The acquisition of forward motility in the sperm of the polychaete Arenicola marina ( L.) (1994) A.PACEY, J.COSSON & M.BENTLEY J.Exp.Biol. 195: 259-280.
46- Pecten maximus spermatozoa quality (1994) C.FAURE, N.DEVAUCHELLE, J-P.GIRARD & J.COSSON, Fisheris Res.( Board of Canada) Vol.I: 28-37.
Studies dealing with oysters sperm (cAMP regulation in the activation mechanism) are pursued in collaboration with 2 laboratoires from IFREMER agency, one in French Britany with Dr Marc Suquet and the second in French Polynesia (Tahiti) with Dr Marina Schneider, on perl oysters in the later case.
7) Development of the techniques used in all these studies:
Throughout all these studies on cilia and flagella, I also developed techniques for observing and analyzing the movement of these organelles endowed with a very small size (about 1 µm in diameter) and with high speed motion (15 to 100 beats per second and > 150 µm/sec).
ILLUSTRATION below : frames obtained every millisecond of a sea urchin spermatozoon (45µm long) and in vitro demembrannated/ reactivated by the ATP: video pictures obtained by high speed strobomicroscopy. The position of each wave (local curvature) can be followed during its progress from head to the distal end of the flagellum. The beat is repeated in an identical fashion 45 times per second.
Brief description of some techniques used for studies of flagellar movement: the high-speed videomicroscopy
In the laboratory, I have developed several techniques for observing the flagella characteristics (72-90-115) that uses video records combined with microscopy and dark field illumination associated with stroboscopy : these techniques make possible the acquisition of images of spermatozoa in movement at an images rate up to 800 per second. For a spermatozoon such as that of sea urchins, the beat cycle is repeated around 40 times per second, we can observe up to 20 consecutive positions inside the same beat cycle corresponding to one image every 800th sec., which, combined with a high resolution microscope at G = 5 to 10000X provides a detailed analysis of the progression of flagellar waves (a form close to a sine wave, but with many variations) and their flatness (32,72,94).
Illustration One can see at the top left an image of individual sperm urchin during swimming in seawater (exposure time 5 microsecond; dark field microscopy; size of the flagellum = 45 µm long and 1µm diameter). The image at top right shows how stroboscopic illumination of the flagellum can revealed in 4 successive positions during the same cycle beat (inteval of 5 milliseconds between 2 positions). The image below shows at higher frame rate (interval of 2 msec. between 2 positions) the details of the progression of the curves from (left to right) head to the distal end of the flagellum.
In addition to the conventional descriptive parameters of flagellar movement (beat frequency, amplitude and wave-length of waves, etc.), the fine analysis conducted from our records allows us a detailed description of the variants adopted by flagella in response to various stimuli to modulate different functions such as activation the sperm flagellum of polychaete (52 & 80) or that of fish (30, 34, 35, 41, 48, 49, 60, 61, 62, 64, 66, 81, 90, 97, 98, 101, 102, 105, 114 & 115,117,118,130), as well as the contraction at dinoflagellates flagella (19 to 21, 24, 31, 122 & 143), or the reptation behavior in salps (77,88) or the dampening of distal waves appearing as a function of time post-activation in fish spermatozoa (64,90,113,115,123); they also allow precise quantification of changes in shape of the axonemal waves as a response to the chemotactic signal (attraction of the egg by sperm, 14 to 17,141,147,148) or when incubated with different antibodies "anti-movement" (36, 39, 56, 58, 68, 70, 71, 89,100, 103,119 & 142) as mentioned earlier in this report. We also observed that in sperm flagella of sea urchins and other species like fish, the successive ciurvatures are not coplanar areas and this allowed highlighting that waves development occurs as three-dimensional ; this lead us to propose a general model (94) to explain the formation of the "3D" curvature (in the proximal flagellum) and its disappearance (in the distal): flagellar waves develop in a double reverse and flattened pinch shape (94).
8) Scientific Production
It is summarized in the table below showing the "impact factor" of recent major journals in which I co-published or published and the number of articles and numbers referring to each of the articles in my publications list.
Publications in Journals with Impact Factor
Journal Title | Impact factor | Number of publications | publications |
J BIOL CHEM | 7.666 | 4 | 10-11-71-142- |
MOL BIOL CELL | 7.527 | 3 | 28-36-89- |
J CELL SCI | 6.044 | 5 | 15-55-68-70-166- |
CRIT REV PLANT SCI | 5.448 | 1 | 122- |
EUR J BIOCHEM | 3.307 | 2 | 12-103- |
BIOCHEM BIOPH RES COM | 3.161 | 2 | 3-4- |
CELL MOTIL CYTOSKEL | 2.772 | 9 | 17-29-53-58-76-78-80-94-123- |
MOL REPROD DEV | 2.658 | 1 | 100- |
J EXP BIOL | 2.354 | 1 | 52- |
THERIOGENOLOGY | 1.923 | 1 | 87- |
REPROD (J REPROD FERTIL) | 1.908 | 4 | 75-101-124-155 |
MAR BIOL | 1.534 | 1 | 88- |
BIOL CELL | 1.477 | 9 | 19-20-21-24-31-33-37-91-161 |
J EXP ZOOL | 1.353 | 1 | 98- |
CRYOBIOLOGY | 1.348 | 2 | 120-183- |
J FISH BIOL | 1.161 | 2 | 97-117- |
AQUACULTURE | 1.137 | 8 | 45-57-65-66-69-112-150-181 |
AQUACULT INT | 1.032 | 3 | 130-131-133- |
9) Current Works
My current work, from an experimental point of view, is more specifically devoted to studies in the regulation of the movement of sperm flagella of oysters and of fish (in Inst. Aquaculture Czech Republic and collaboration with several laboratories in France and abroad). I also recently co-published a book in this field entitled "Fish spermatology" (Alpha Press) and in which I wrote two chapters. In addition, I also published two journal articles in this area. Furthermore, I am frequently requested as an expert in this field, either as a "referee" or as part of the committee of various PhD thesis. This expertise is also accompanied by frequent visits to foreign laboratories with which I have longstanding relations of exchange: USA (Kentucky Univ), the sturgeon and fish spatula; Czech Republic (Inst. of Aquaculture, Vodnany, Univ of South Bohemia) and Iran (Sturgeon Institute, Racht) on the sturgeon, in China concerning sturgeon of the Yangtze and in Japan on salmonids and ascidians (Misaki Marine Station of University of Tokyo); in Poland, the Academy of Sciences (Dr. Andzej Ciersko, Olstyn), Spain, on tuna; in Norway (Univ. of Bodo) on salmons, cod and hake.
Another part of my current interest in egg chemotaxis to sperm is represented by the long lasting collaboration with Prof. M. Morisawa in Misaki Marine Station (Japan). Another collaboration with G. Prulière (UMR7009, Villefranche sur mer France) is dealing with studies on ciliogenesis in sea urchin embryos during early embryogenesis. My expertise in the movement of flagella brings me to collaborate with other French laboratories: study of algae-feeding used in aquaculture oysters (Robert R. Laboratory, IFREMER Brest), study of sperm from oysters (Mr. Suquet Laboratory, IFREMER - Brest and laboratory M. Schneider, IFREMER - Tahiti), study the movement of trypanosomes (P. Bastin Laboratory, Pasteur Institute, Paris), studies of sperm in the Tilapia fish(IRD – Montpellier, France) as well as in sea bass and tuna (C. Fauvel, Palavas IFREMER France) and more recently on gregarines, parasitic unicells.
All these national and international collaborations also helped me and I can still accomplish various tasks mentoring other researchers with whom I co-authored many publications. Post-doctoral researchers like Alan Pacey (semen arenicola) who stayed one year in my laboratory. PhD and PhD students as L. Chauvaud (semen turbot), G. Perchec (carp semen), C. Dreanno (semen turbot), C. Faure (semen and oyster shell St Jacques), H. Alavi (semen of many species including sturgeon) and F. Abascal (semen bar and tuna). Students of Erasmus as well as those of IUT French were welcomed each year in my laboratory between 1993 and 2005. I also participated in courses and practical work in cell biology of reproduction in France (University of Nice, Paris 6 and French Polynesia) and abroad (Japan, Iran, USA, Czech Republic, Mexico, Norway, China). Finally I attended numerous thesis committees. Presently, I am supervisor of 3 PhD students (V. Dzyuba, Ievgeniia Gazo and Galina Prokopchuk) and co-tutor several other PhDs (Olga Bondarenko, Anna Shalutyna , Volodymyr Bondorenko) at the Univ. South Bohemia, Dept of Fisheries and Quality of Water (Czech Republic).
Mobility during my career:
Apart from numerous trips short or medium term, I conducted two years post-doctoral studies in the U.S., a 3-months stay in Japan and I foresee a stay of 12 months at the University of French Polynesia (teacher-researcher). I decided to move my job place when I arrived at the Marine Station of Villefranche near Nice where I became interested in gametes of marine animals including sea urchin and jelly-fishes (siphonophores) and gradually to cilia and flagella more specifically.
Meetings with the public and conferences popularization of science in the recent past
> Participation in the exhibition "Light" at the Palais de la Découverte (Paris, December 2007) organized by the CNRS animation showing the public fertilization of eggs of sea urchins.
> Participation to a public exhibition at the Trocadero, 20 November to 2 December 2008 organized by the CNRS with animation: "Deciphering the sea urchin to understand the man."
Development of several Web sites:
- a site on sturgeon (fish spatula and Sturgeons in general), the biology of reproduction and aquaculture; see http://biodev.obs-vlfr.fr/ cosson ~ / Webcaviargood / index.html
- a site on the chemotaxis sperm / egg (in development)
- showing a video by the movement of sperm of many species of fish; see http://biodev.obs-vlfr.fr/ cosson ~ / fishsperm / fishsperm.html
- a site on the different types of movement among dinoflagellates; see http://biodev.obs-vlfr.fr/ cosson ~ / Dinoflagellates / Dinoflagellates / Dinoflagellates.html
Organization of and participation to conferences and workshops in the recent past:
> January 2004 = Guest speaker for an oral presentation on the flagellar movement at the University of Tokyo (Japan): International Symposium "The biology of sperm cell - from basic to clinical aspects."
> January 2005 as guest lecturer at New Orleans (USA) at the International Symposium of the Aquaculture Society on the movement of sperm sturgeon.
> November 2006 = Guest speaker in several institutes in Wuhan and Jin Zu (China): cryopreservation of sperm movement and fish chondrostéens (sturgeon fish and spatulas)
> April 2007 = Organizer and guest speaker at the "International Workshop on Fish Sperm" organized at the Institute of Aquaculture deVodnany (Czech Republic) on cryopreservation and techniques to measure movements of fish sperm.
> June 2007 = Lecturer at the "8th International Symposium on Reproductive Physiology of Fish" (Saint-Malo, France): presentation of several conferences on the results achieved on various fish species.
> August 2007 = Organizer and guest speaker at the "First International Conference on Fish Sperm" organized at the Institute of Aquaculture of Vodnany (Czech Republic).
expertise
> Request for frequent evaluations of aquaculture and feasibility of sperm cryopreservation of fish.
> Member of the reading of the journal Cell Biology International.
> Referee for many scientific journals in the field of gametes, their cryopreservation and aquaculture mainly.
> Publisher invited by the Journal of Applied Ichtyology and the Theriogenology journal
Research grants:
A tripartite exchange initially focusing on the study of gynogenesis in fish spatula (1996-2000) and then focused on the cryopreservation of sperm of these species (paddle-fish and sturgeon) in association with the Aquaculture Research Kentucky Center (USA) and the Institute of Fish Culture (Vodnany, Czech Republic) for the years 2001-2004 and funded by the U.S. Ministry of Agriculture. This contract has enabled the development of basic techniques to manipulate the gametes of these species, successfully artificial reproduction (including gynogenesis) and establish the right conditions for the cryopreservation of their sperm.
Other grants: In the recent past, several contracts with IFREMER, one on aquaculture and manipulation of gametes oysters and scallops St Jacques (during successive years), another contract on aquaculture of turbot, manipulation of their sperm cryopreservation and another on the movements of unicellular algae used for the growth of oyster larvae.