Seminal characteristics and sensitivity of Astyanax lacustris (Characiformes: Characidae) sperm to cryoprotective solutions based on dimethylsufoxide and methylglicol

This study aimed to determine the semen characteristics of Astyanax lacustris after hormonal induction and to evaluate the sensitivity of the species sperm to cryoprotective solutions based on the cryoprotectants dimethyl sulfoxide and methyl glycol. Volume, color, sperm concentration, total motility and aspects of sperm movement were analyzed using "Integrated Semen Analysis System". Three different extenders were tested: A) glucose 5%+egg yolk 10%, B) BTS®5% and C) glucose 5% and two permeable cryoprotectants: dimethyl sulfoxide (Me2SO) and methyl glycol (MTG). Fresh A. lacustris semen presented total motility of 76.6±11.2%, motility duration of 33.0±2.2s, sperm concentration of 7.22±3.2×109sptz/mL and seminal osmolality of 219±0.03mOsm/kg-1. The toxicity test showed the highest total motility values at the MTG15%+A, Me2SO15%+B and Me2SO10%+C dilutions, and the Me2SO10%+C and Me2SO15%+C dilutions presented the highest values for curvilinear velocity, linear velocity and average velocity. The tested protocol was not effective at maintaining the viability of A. lacustris semen after freezing because no motility was observed in any of the dilutions. However, the Comet Assay demonstrated that cryoprotectant solutions were effective in protecting the genetic material of cells, as DNA damage levels were low, with no difference between control and Me2SO10% + A, dilutions MTG10%+C, Me2SO10%+B and Me2SO15%+B.(AU)

O objetivo deste estudo foi determinar as características do sêmen de Astyanax lacustris após indução hormonal e avaliar a sensibilidade dos espermatozoides da espécie a soluções crioprotetoras baseadas nos crioprotetores dimetilsulfóxido e metilglicol. Volume, cor, concentração espermática, motilidade total e aspectos do movimento espermático foram analisados usando o "Sistema Integrado de Análise de Sêmen (ISAS®CASA)". Três extensores diferentes foram testados: A) glicose 5%+gema de ovo 10%, B) BTS® 5% e C) glicose 5% e dois crioprotetores permeáveis: dimetilsulfóxido (Me2SO) e metilglicol (MTG). O sêmen fresco de A. lacustris apresentou motilidade total 76,6±11,2%, duração da motilidade 33,0±2,2s, concentração de espermatozoides 7,22±3,2×109sptz/mL e osmolalidade seminal 219±0,03mOsm/kg-1. O teste de toxicidade apresentou maiores valores de motilidade total nas diluições MTG15%+A, Me2SO15%+B e Me2SO10%+C, e as diluições Me2SO10%+C e Me2SO15%+C apresentaram maiores valores de velocidade curvilínea, velocidade linear e velocidade média. O protocolo testado não foi eficaz em manter a viabilidade do sêmen de A. lacustris pós-congelamento, pois não foi observada motilidade em nenhuma das diluições. No entanto, o Ensaio Cometa demonstrou que as soluções crioprotetoras eram eficazes na proteção do material genético das células, pois os níveis de dano ao DNA eram baixos, sem diferença entre controle e Me2SO10%+A, MTG10%+C, Me2SO10%+B e Me2SO15%+B.(AU)

Hormonal induction of Brycon cephalus (Characiformes, Characidae) to spermiation using D-ala6, pro9net-mGnRH + metoclopramide.

This study aimed to establish a hormonal induction protocol for spermiation of Brycon cephalus males, using Ala6, Pro9Net-mGnRH + metoclopramide (Ovopel®). Thus, 20 males were used divided into three inductor treatments [⅓ pellet/kg (T1), ⅔ pellet/kg (T2) and 1⅓ pellet/kg (T3)] and one control group (CO), which only received physiological solution applications (0.9% NaCl). All treatments were applied in a single dose. For evaluation of the availability of the treatment, the following seminal parameters were analyzed: seminal volume, subjective spermatic motility, duration of motility, pH, osmolality and spermatic concentration. T3 showed the highest seminal volume (4.66 ± 1.52 ml), and was significantly different in comparison with T1 (2.0 ± 0.9 ml), T2 (3.5 ± 1.3 ml) and CO (2.3 ± 1.2 ml). In relation to spermatic motility, T2 and T3 showed significantly higher levels [5, (81-100%)]. However, T3 showed significantly lower average sperm motility duration than T1, T2 and CO (30 ± 7 s; 28 ± 6 s; 32 ± 8 s, respectively). With regard to the seminal parameters of spermatic concentration, pH and osmolality, no significant variation was verified among treatments. In conclusion, mGnRH + metoclopramide used for hormonal induction of B. cephalus reproduction does not induce changes related to spermatic concentration, pH and osmolality parameters of the seminal fluid and the most adequate doses among tested treatments were ⅔ pellet/kg live fish.