Motilidade espermÃtica de sÃmen de peixes criopreservado em diferentes meios avaliada por mÃtodo subjetivo e computadorizado / Motility of fish sperm cryopreserved in different freezing media evaluated subjectively and by computerized system.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

Pirapitinga (Piaractus brachypomus) and curimba (Prochilodus lineatus) are Characiforme fish species, of economic and ecological importance. The aims of this study were to (a) evaluate different freezing media for semen of both species; (b) compare post-thaw sperm motility subjectively evaluated under light microscope and computerized system SCAÂ for both species and (c) determine post-thaw sperm velocities by SCAÂ for both species and; (d) establish a correlation between the sperm velocities and the fertilization rates for curimba. Pirapitinga semen was diluted in four freezing media prepared with two extenders (glucose and BTSÂ) combined with two cryoprotectants (methylglycol and DMSO) and frozen nitrogen vapor. Semen was thawed, sperm motility was evaluated both subjectively under light microscope and objectively by computer system SCAÂ and the curvilinear velocity (VCL), average path (VAP) and straight line (VSL) were calculated. Curimba semen was diluted in two semen extenders (ACPÂ and glucose) combined with methylglycol as cryoprotectant and frozen in nitrogen vapor. Half of the samples were evaluated for motility and sperm velocity, as described for pirapitinga. The other half was evaluated for the capacity to fertilize fresh oocytes from three females. In both pirapitinga and curimba, there was no difference in post-thaw sperm motility evaluated either subjectively or by computer system. In pirapitinga, semen cryopreserved in glucose-methylglycol yielded higher motility (81%) and velocities compared to semen cryopreserved in the other media. In curimba, semen cryopreserved in ACPÂ yielded higher motility (84%) than semen cryopreserved in glucose (75%), however fertilization rates and sperm velocities were similar among samples cryopreserved in both extenders. A positive correlation was observed between fertilization rate and sperm velocity. The cryoprotectant methylglycol was more efficient than DMSO for pirapitinga semen, as observed in other Characiformes. Glucose is a simple extender, available in drugstores and, combined with methylglycol, is an excellent freezing medium for semen of both fish species studied here.

ASSUNTO(S)

fish criopreservaÃÃo aquicultura sÃmen sperm peixe cryopreservation

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