Periódicos Brasileiros em Medicina Veterinária e Zootecnia

p. 62-70

Initiation and s uppression of sperm motility is osmolality dependent in two South American fish species: streaked prochilod (Prochilodus lineatus) and piracanjuba(Brycon orbignyanus)

Gonçalves, A C SNascimento, A FCosta, A CLeal, M CViveiros, A T M

Solutions to induce or suppress the initiation of sperm motility in fish ha ve been used to improve reproductive success during artificial fertilization and preservation techniques . The aim of the present study was to evaluate the effects of three solutions (NaCl, glucose , and BTS™) - each prepared with 10 different osmolalities - on the initiation and suppression of fresh sperm motility in Prochilodus lineat us and Brycon orbignyanus . Sperm was diluted in each of the 30 solution s and immediately observed under a light microscope to determine which solution s trigger ed or suppress ed the initiation of sperm motility. When present, motility rate ( % motile sperm ) w as determined at 0, 30 , and 120 s post - activation and the motility quality score ranging from 0 ( no movement ) to 5 ( rapidly swimming sperm) was determined at 0 and 30 s post - activation . Osmolality , but not solution composition , significantly affected both motility rate and quality score . Solutions at osmolali ties up to 270 mOsm/kg in P. lineatus and up to 180 mOsm/kg in B. orbignyanus induced motility in at least 60% of sperm , with a minimum quality score of 3.0 , and were therefore classified as activating agents. The greatest motility at 0 , 30 , and 120 s post - activation was observed with solutions ranging from 135 to 225 mOsm/kg for P. lineatus and at 135 mOsm/kg for B. orbignyanus . On the other hand, solutions ranging from 360 to 450 mOsm/kg in P. lineatus and 270 to 450 mOsm/kg in B. orbignyanus suppressed motility in at least 95% of sperm and were classified as immobilizing media . The osmolality of the surrounding medium is the key factor in the initiation or suppression of sperm motility in P. lineatus a nd B. orbignyanu.(AU)

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