Use of antioxidants on rainbow trout Oncorhynchus mykiss (Walbaum, 1792) sperm diluent: effects on motility and fertilizing capability

The present investigation determined how different antioxidants incorporated into the sperm diluent for cold storage of semen affected sperm motility and spermatozoan fertility capabilities of the rainbow trout. For the evaluations, fresh semen (C) and semen that had been stored without diluents (T1) were used as control groups. The diluents were prepared using a base of UCT diluents (T2), adding grape polyphenol (0.1 g 100 mL-1) (T3), trolox C (0.1 g 100 mL-1) (T4), polyphenol (0.1 g 100 mL-1) plus trolox (0.1 g 100 mL-1) (T5), and vitamin C (0.018 g 100 mL-1) (T6). The incorporation of antioxidants into sperm diluents prolongs motility and fertility of rainbow trout semen. The results show that by day two, all of the treatments showed level 5 sperm motility. After seven days of storage, only T3 and T6 dropped to level 4 sperm motility. The duration of flagellate activity on this day was maximal for T3 with 36.87 ± 0.51 s and minimal for T6 with 29.78 ± 0.52 s. On day seven, fertility was maintained with no statistically significant differences between the control and T2 (92.80 ± 0.62%), T3 (83.66 ± 2.52%), T4 (90.46 ± 1.60%), T5 (83.57 ± 2.75%), and T6 (83.57 ± 2.30%). By days 10 and 17 of storage, the fertility of T1 was zero and that of T2 was significantly lower than the control group. On day 17, the highest percentage of fertilization was 97.38 ± 1.85% for T5 and the lowest value was 64.69 ± 3.76% for T2. The results allow concluding that the sperm viability of semen stored with different antioxidants is significantly prolonged

Nuclear DNA content in Galaxias maculatus (Teleostei: Osmeriformes: Galaxiidae)

The nuclear DNA content (2C value) was determined in the commercial fish Galaxias maculatus (Galaxiidae) was determined by microdensitometry of erythrocyte nuclei after Feulgen staining; rainbow trout erythrocytes with a known 2C value were used as a standard. The 2C value of G. maculatus was 2.21 ± 0.12 pg and its C value was equivalent to 1.105 pg (1,082.9 Mbp). This C value is within the range recorded for other osmeriform species (0.62-3.2 pg). The average sperm head diameter of G. maculatus is lower than the average sperm head diameter of rainbow trout (used as a standard), which coincides with the differences observed in the nuclear DNA content of both species. This information increases the genome data available for G. maculatus and might be useful in future programs dealing with its genetic manipulation

Nuclear DNA content in the red conger eel Genypterus chilensis (Guichenot, 1881) (Actinopterygii: Ophidiidae)

Indexación: ScieloStudies about nuclear DNA content in the genus Genypterus are scarce, and the present study gives the first estimate of nuclear DNA content of Genypterus chilensis, with a value of 2C= 1.0 + 0.06 pg, value close to that obtained for other Ophidiidae species wich range between 1.2 and 1.68 pg.Los estudios sobre contenido de ADN nuclear en el género Genypterus son escasos, y el presente trabajo entrega por primera vez la estimación del contenido de ADN nuclear de Genypterus chilensis con un valor 2C = 1,0 + 0,06 pg, valor cercano al descrito para otras especies de Ophidiidae que varían entre 1,2 y 1,68 pg

Crecimiento de juveniles de congrio colorado Genypterus chilensis en condiciones de cultivo

El congrio colorado Genypterus chilensis (Guichenot, 1848) es un pez altamente demandado por el mercado chileno. Las capturas han disminuido y mantenido bajo 1.000 ton anuales en la década 2000-2010 con un precio de US$7 kg-1. El objetivo de este trabajo fue evaluar el crecimiento de juveniles de primera generación producida de padres silvestres en condiciones de cultivo. Se estimó el crecimiento de 128 juveniles durante cinco meses en el hatchery del CIMARQ, Valparaíso, Chile, distribuidos en cinco grupos de talla en estanques con agua marina (35 g L-1) y rango de temperatura de 12-14°C. Los pesos promedios iniciales variaron desde el grupo menor de 4 g (11 cm) al mayor de 23 g (18 cm). Estos fueron alimentados con pellet comercial para peces marinos. Se midió mensualmente la longitud total (cm), peso (g) y se estimó sus promedios, porcentaje de crecimiento en peso, tasa de crecimiento específico, coeficiente de crecimiento termal y factor de conversión. A los cinco meses el grupo menor alcanzó un peso promedio de 16 ± 7 g (16 ± 2 cm) y el mayor 75 ± 17 g (27 ± 6 cm). Los pesos promedios mensuales se ajustaron con R² = 0,9 a las ecuaciones P = 3,845e0,300t y P = 20,63e0,240t. Los factores de conversión fluctuaron entre 8,6 y 0,3 al mes 5 para el grupo menor y de 0,6 a 0,2 para el mayor. Si se proyecta el crecimiento desde el peso inicial de 4 y 23 g hasta el peso de cosecha de 2 kg, éste se obtendría entre 26 y 18 meses para los grupos menor y mayor respectivamente