K. Kato et al., Viability, growth and external morphology of meiotic- and mitotic-gynogenetic diploids in red sea bream, Pagrus major, J APP ICHTH, 17(3), 2001, pp. 97-103
Two types of gynogenetic diploids were artificially induced in the red sea
bream (Pagrus major Temminck et Schlegel), either by suppressing the first
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 e
rg mm(-2)) sperm of Japanese parrot fish (Oplegnathus fasciatus Temminck et
Schlegel), and hydrostatic pressure shock of 700 kg cm(-2) for 5.5 min at
46 min after insemination (naitotic-G2N) and cold shock of 1 degreesC for 3
0 min at 3 min after insemination (meiotic-G2N) were applied to the eggs, s
equentially, 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 a
nd 45.8%, and 12.8 and 35.0%, respectively. The induction of mitotic-G2N wa
s confirmed by isozyme marker analysis. The standard deviations, variances
and coefficients of variation of the body weight, standard length and body
depth in 91-day-old juveniles were always large in mitotic-G2N, small in no
rmal-2N and intermediate in meiotic-G2N. The variances in the number of pec
toral fin rays and caudal fin rays of mitotic-G2N were significantly 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 meioti
c- and mitotic-G2N were significantly lower than those of normal-2N. Both G
2N survived for 3 years to the adult stage.