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Spermatozoa that are quiescent in electrolyte and nonelectrolyte solutions isotonic to seminal plasma show motility when the semen is diluted with hypotonic solution in freshwater teleosts (four species tested) and with hypertonic solution in marine teleosts (five species tested). Decrease or increase, respectively, in osmolality of the environment may be(More)
Spermatozoa of rainbow trout and chum salmon, which have no potential for motility in the testis, acquire that potential in the sperm duct. This paper demonstrates that there is little difference between the levels of sodium, potassium, calcium, magnesium, chloride and osmolality of the seminal plasma in the testis and in the sperm duct. However, the(More)
Change of osmolality surrounding spawned sperm from isotonic to hypotonic causes the initiation of sperm motility in the common carp. Here we show that membrane-permeable cAMP does not initiate motility of carp sperm that is quiescent in isotonic solution, and that motility of the demembranated sperm can be reactivated without cAMP. Furthermore, the cAMP(More)
We previously demonstrated that osmolality isotonic to the seminal plasma suppresses sperm motility in marine and freshwater teleosts, and exposure of sperm to hypertonicity of sea water or hypotonicity of fresh water, respectively, induces the initiation of sperm motility at spawning. The motile sperm became immotile by return of osmolality to the isotonic(More)
Chemotactic swimming behaviors of spermatozoa toward an egg have been reported in various species. The strategies underlying these behaviors, however, are poorly understood. We focused on two types of chemotaxis, one in the siphonophores and the second in the ascidians, and then proposed two models based on experimental data. Both models assumed that the(More)
Two native forms of vitellogenin (EIP1 and EIP2) were identified in the plasma of Oreochromis niloticus. They were present in females and were estrogen-inducible in males. Both were phosphoglycolipoproteins and both immunoreacted with the antiserum raised against egg proteins. Two prominent bands (EIpp1 and EIpp2; corresponding to 185 and 120 kDa,(More)
Exposure to hypo-osmotic or hyperosmotic environment triggers the initiation of fish sperm motility. In this article, we report that calcium and potassium channel blockers do not influence motility of puffer fish sperm but calmodulin antagonists reversibly decrease it, suggesting that calmodulin-Ca(2+) interactions are prerequisite for the initiation of(More)
Sperm chemotaxis toward eggs before fertilization has been demonstrated in many animals and plants, and several peptides and small organic compounds acting as chemoattractants have been identified. We previously showed that sperm of the ascidians Ciona intestinalis and Ciona savignyi are activated and then attracted toward the egg by a common factor(More)
Proteasomes are involved in ATP-dependent regulation of sperm motility in salmonid fish. We have demonstrated here by immunoelectron microscopy that proteasomes are located at the structure of the chum salmon sperm flagellum that attaches at the base of the outer arm dynein and extends toward the plasma membrane. Furthermore, substrates and inhibitors of(More)