日時：２０１８年１１月１９日（月）１７時００分〜
場所：東京大学大学院理学系研究科・附属臨海実験所・セミナー室
講演者：Vitaliy Kholodnyy (Faculty of Fisheries and Protection of Waters, University of South Bohemia in České Budejovice)
懇親会： １９時００分〜
Vitaliy Kholodnyy (Faculty of Fisheries and Protection of Waters, University of South Bohemia in České Budejovice)
「Gametes collision in fresh water fish: evidences of guidance and selection」
Externally fertilizing species, especially freshwater fish, reproduce in an environment being very harsh for gametes. They undergo the pressure of various external factors (temperature, water flow, pH, ion composition, viscosity, presence of ovarian fluid etc.). Variabilty in cell responces to these parameters creates the wide spectrum of reproduction strategies. Existence of specific mechanisms for guiding and triggering the encounter of gametes would be highly expedient in these conditions, nevertheless only scarse information exist on this issue. The existing data and performed by us observational studies support the idea that the factors, which are the part of ovarian fluid or released by the eggs could significantly affect the behavior of male gametes and to influence the outcome of fertilization. This could be made by the support of sperm motility traits on certain level, attraction or repulsion of gametes with some pre-defined qualitative characteristics and targeted promotion of sperm with proper genetic material to encounter the egg. The specific mechanisms supporting the potential selection by externally fertilizing females are unclear. In addition to chemical agents there is evidence that some physical factors, e.g. presence of surfaces and their features, contribute to fertilization performance. All these phenomena, i.e. motility activation and progress, kinetic and tactic effects, possible selection and promotion of gametes could be the elements in the guidance pattern. This is even more challenging for freshwater fish reproduction, considering very limited period of motility comparing to marine species, and makes the need of specific support of gametes encounter even more apparent. Apparently, guidance during fertilization is a rule, not a fortune, at least, because guidance is highly expedient during external fertilization in terms of environmental variability and stability of living matter.