Search

Genetic (DNA) inactivation of fish sperm with ultraviolet irradiation is generally accompanied by a paradoxical effect on survival rates (Hertwig effect). In the present study, sperm samples from ten male bullseye puffer fish (Sphoeroides annulatus) were diluted 1:50 using Cortland's extender solution and used to test the effect of nine ultraviolet doses (0.2–1.0 J cm–2) on motility time in seconds, motility index, and embryo survival rate after fertilizing eggs from five bullseye puffer females. Motility time of sperm irradiated with 0.2–0.9 J cm–2 were not statistically different from the controls, but sperm irradiated with a dosage of 1.0 J cm–2 dosage had significant lower motility time. Motility indices (MI) allowed for the statistical differentiation of four groups in relation to their response to different radiation doses: the first had high MI, and included the controls and 0.2–0.3 J cm–2 treatments; the second had lower MI and included the 0.4–0.7 J cm–2 treatments; the third showed recovery of MI and included the 0.8–0.9 J cm–2 treatments; and the fourth showed the lowest MI with the 1.0 J cm–2 treatment. Embryo survival was highest for the controls and 0.2 J cm–2 treatment, decreasing in the 0.3–0.4 J cm–2 treatments, increasing again in the 0.5–0.8 J cm–2 treatments, until reaching lowest survival in the 0.9–1.0 J cm–2 treatments. These results indicate that the best ultraviolet dosage to achieve genetic inactivation of sperm of this species is close to 0.7 J cm–2, a dosage in which fish fry showed typical haploid syndrome characteristics.

El cariotipo de Plicopurpura pansa y P. columellaris fue determinado a partir de 17 y 13 especímenes adultos respectivamente. Adicionalmente, se utilizaron ocho cápsulas de P. pansa. Contamos 186 campos mitóticos en P. pansa: 59 en los adultos y 127 en los embriones; y 118 campos en P. columellaris. En ambas especies se observaron números cromosómicos desde 30 hasta 42. Las variaciones en número cromosómico fueron identificadas en cada individuo, no habiendo ninguna relación con los tejidos (branquias, músculo y estómago) empleados. El número modal diploide típico fue de 2n=36 cromosomas en ambas especies. En los especímenes adultos seleccionamos cinco de las mejores dispersiones cromosómicas para armar el cariotipo. Calculamos los estadísticos citogenéticos clásicos, longitudes relativas, proporción de brazos, índice centromérico y la diferencia entre brazos. Identificamos en ambas especies tres pares de cromosomas metacéntricos y quince pares de cromosomas telocéntricos. Esta clasificación no fue suficientemente robusta, por lo que dividimos el complemento cromosómico de cada especie en cuatro grupos ("a", "b", "c" y "d") utilizando como criterio las longitudes relativas (p+q). Hubo diferencias significativas entre grupos cromosómicos por especie y entre especies, los tres primeros pares de cromosomas (grupo "a" birrámeos) y los dos últimos pares (grupo "d" monorrámeos menores) (análisis de varianza de dos vías, pKaryotypes of the purple snails Plicopurpura pansa and Plicopurpura columellaris (Gastropoda: Muricidae). The karyotypes of the purple snails Plicopurpura pansa (Gould, 1853) and P. columellaris (Lamarck, 1816) were established from 17 and 13 adults, respectively; and from eight capsules with embryos of P. pansa. In P. pansa were counted 59 mitotic fields in the adults and 127 in embryos; and 118 fields in P. columellaris. Chromosome numbers from 30 to 42 were observed in both species. Such a variation was notorious in each sample and there was no evidence of any relationship with tissue (gill, muscle and stomach). Both species has a typical modal number of 2n=36 chromosomes. Five good quality chromosome spreads were selected from adults of each species to assemble the karyotype. Classic cytogenetics statistics like relative lengths, arm ratio, centromeric index and the difference between long and short arms are presented. There were three pairs of metacentric and fifteen pairs of telocentric chromosomes in both species. This classification was not strong enough, so the chromosome complement by species was divided in four groups ("a", "b", "c" and "d") on the basis of relative lengths (p+q). A comparison of p+q in each chromosome pair was estimated within and between species by two ways analysis of variance and Tukey tests (P