, FIGUEROA VILLALOBOS, ELIAS GUSTAVO, VALDEBENITO ISLER, NEMESIO IVAN, Dumorné, Kelly, Valdebenito, Iván, Contreras, Pablo, Rodríguez, Patricio Ulloa, Risopatron, Jennie, Villalobos, Elías Figueroa, Estevez, Manuel Lee, Díaz, Rommy, Farias, Jorge G.

In this research we evaluated simple aspects of the sperm biology of Genypterus blacodes, in particular assessing the effects of pH (6, 7, 8 and 9), temperature (4, 8 and 16 °C) and osmolalities 100% sea water (1010 mOsm/kg, Control), 75% sea water (774 mOsm/kg, T1), 50% sea water (488 mOsm/kg, T2) and distilled water (0 mOsm/kg, T3)) on the motility of Genypterus blacodes intratesticular spermatozoa. In addition, we determined the fertilization rate. Our results show that G. blacodes spermatozoa have a sperm density of 5.35 ± 0.16 × 109 spermatozoa/mL. Sperm motility is initiated on contact with a hyperosmotic swimming medium under normal conditions (1010 mOsm/kg, pH 8 and 8 °C). The longest motility duration (432.48 ± 8.89 s) was recorded at 4 °C. The maximum percentage of motile cells was recorded at 8 °C (65.66 ± 4.95) at osmolality 1010 mOsm/kg, whereas an optimum was observed at pH 8. The fertility rate was 73.9 ± 17%. This is the first report on sperm motility of G. blacodes spermatozoa. In conclusion, the results of this study permit a baseline to be established for further research and protocols for artificial reproduction of this species to be developed and optimized. In addition, the information gathered in this research will be useful for developing the biotechnology of Genypterus blacodes. © 2018 Elsevier B.V., All rights reserved.

, FIGUEROA VILLALOBOS, ELIAS GUSTAVO, VALDEBENITO ISLER, NEMESIO IVAN, Dumorné, Kelly, Valdebenito, Iván, Risopatron, Jennie, Villalobos, Elías Figueroa, Díaz, Rommy, Farias, Jorge G.

In this study, the morphology and ultrastructure of Genypterus blacodes spermatozoa were characterized through scanning and transmission electron microscopy. Findings revealed that the G. blacodes spermatozoa can be differentiated into three major parts: a spherical head without an acrosome (typical for externally fertilizing fish), a short mid-piece, and a long flagellum. The mean length of the spermatozoa was 57.6 ± 6.08 ?m, with flagella accounting for 56.2 ± 7.2 ?m. The head was 1.47 ± 0.2 ?m long, and 0.89 ± 0.06 ?m wide. The mid-piece had a total dimension of 0.72 ± 0.16 ?m, and was 0.31 ± 0.02 ?m in length and 0.6 ± 0.05 ?m in width. It was located lateral to the nucleus and contained 4 or 5 spherical mitochondria. The mitochondria were separated from the axoneme by a cytoplasmic canal. The main piece of the flagellum had short irregular side-fins, and the axoneme was composed of the typical 9 + 2 microtubular doublet structure enclosed by a cell membrane. The present study reveals that G. blacodes sperm can be categorized as a primitive type. This study is the first to provide comprehensive details on the morphology and ultrastructure of spermatozoa in G. blacodes. © 2018 Elsevier B.V., All rights reserved.