Viability, growth and external morphology of meiotic- and mitotic-gynogenetic diploids in red sea bream, Pagrus major

Abstract

Two types of gynogenetic diploids were arti®cially induced in the red sea bream (Pagrus major Temminck et Schlegel), either by suppressing the ®rst cell cleavage (mitotic-G2N) or by retaining the second polar body (meiotic-G2N). The eggs of red sea bream were inseminated with UV-irradiated (3000 erg mm )2 ) sperm of Japanese parrot ®sh (Oplegnathus fasciatus Temminck et Schlegel), and hydrostatic pressure shock of 700 kg cm )2 for 5.5 min at 46 min after insemination (mitotic-G2N) and cold shock of 1°C for 30 min at 3 min after insemination (meiotic-G2N) were applied to the eggs, sequentially. The total hatching rate and hatching rate of normal larvae of the normal diploid, meiotic-G2N and mitotic-G2N were 86.5 and 94.9%, 38.1 and 45.8%, and 12.8 and 35.0%, respectively. The induction of mitotic-G2N was con®rmed by isozyme marker analysis. The standard deviations, variances and coecients of variation of the body weight, standard length and body depth in 91-day-old juveniles were always large in mitotic-G2N, small in normal-2N and intermediate in meiotic-G2N. The variances in the number of pectoral ®n rays and caudal ®n rays of mitotic-G2N were signi®cantly higher than those of normal-2N. The incidences of deformities were highest in the mitotic-G2N group. The survival rates and growth performance of the meiotic-and mitotic-G2N were signi®cantly lower than those of normal-2N. Both G2N survived for 3 years to the adult stage.

Genetic basis and biotechnological manipulation of sexual dimorphism and sex determination in fish

“…Through a combining approach of artificial gynogenesis and sex reversal, all-female population was also produced in common carp and used for aquaculture practice [60]. Recently, artificial gynogenesis has been performed in many marine fish species, such as flounder [168], red sea bream (Pagrosomus major) [169], sea bass [170], spotted halibut (Verasper variegatus) [171], and half-smooth tongue soles [172]. Generally, the gynogenetic offspring is composed of all-females.…”

Morphological Variability Between Wild Populations and Inbred Stocks of a Chinese Minnow, Gobiocypris rarus

“…In fact, many studies have shown that morphometric variations occur during inbreeding. Kato et al (2001) studied the external morphological variation in red seabeam (Pagrus major) between two types of gynogenetic diploids and normal diploids. Leary et al (1983) argued that inbreeding may affect the developmental stability of morphometric traits, because the lack of enzymatic diversity in homozygotes reduces the efficiency of normal developmental homeostatic processes.…”