Induction of gynogenesis and gonad development in the muskellunge

Abstract

Muskellunge Esox masquinongy eggs activated with UV-irradiated yellow perch Perca flavescens sperm were subjected to heat shock at 31 1 C for 6 min, 20 min after fertilization in three experiments. Survival at eyed stage was 1·7 1·6, 6·8 4·8 and 2·3 0·5% in experiments I, II and III, respectively. After rearing the gynogenetic muskellunge in troughs and then in ponds, the sex ratio of gynogens in experiment I did not significantly (P>0·05) differ from the expected ratio 0 : 1 (male : female), however, one male and one intersex were observed. In experiments II and III, the sex ratio of gynogens differed significantly from expected (0 : 1). Three months after hatching, the growth of females did not significantly (P>0·05) differ among control and gynogenetic groups, whereas male growth was significantly (P<0·01) higher in the control v. gynogenetic group. The histological structures of the gynogenetic fish gonads in both sexes were similar to those described in the gonads of control muskellunge. After the overwintering period, signs of active spermatogenesis were observed in the testis of 1+ year old gynogenetic fish, whereas ovaries contained only oocytes at the perinucleolar stage. At this stage, plasma sex steroids testosterone (T) and oestradiol-17 (E2) cannot be used to discriminate the sex of gynogenetic muskellunge, as intersex, male and female fish had similar levels of T and E2.

Histological Observation on Adult Gonads from Meiogynogentic Olive Flounder Paralichthys olivaceus

“…Even if the morphologically deficient gonads were found in the meiogynogenetic samples, their ovaries except thread-like undeveloped gonads all proceeded into phase II and displayed a synchronous development level when compared to control females in view of histological results. Similar cases were observed in the gynogenetic gonads of muskellunge (Rlnchard et al, 2002) and bagrid catfish (Park et al, 2007). The yolk vacuoles, landmark of early stage III ovaries, only emerged from one ovarian slice of control female flounders in Fig.…”

Growth, Maturation, Induced Spawning, and Production of the First Generation of South American Catfish, Pseudoplatystoma sp., in North America

“…The tissues were dehydrated in a series of ethyl alcohol and xylene baths and embedded in paraffin. Thin sections (5 μm) were cut, mounted on albumin‐coated slides, stained in Mayer’s hematoxylin and eosin, and examined by light microscopy (Rinchard et al 2002).…”

Artificial gynogenesis in Cynoglossus semilaevis with homologous sperm and its verification using microsatellite markers

“…In 2006, shortnose sturgeon meiotic gynogenetic diploids were successfully induced and the sex ratio (male/female) of meiotic gynogens was 35%:65%, significantly different from the theoretical ratio of 1:1 (Flynn et al 2006). The sex ratio (male/female/intersex) of gynogenetic muskellunge Esox masquinongy (a female heterogamety system) in three experiments was, respectively, 1:10:1, 24:11:0 and 17:11:1 (Rinchard, Garcia‐abiado, Dabrowski, Ottobre & Schmidt 2002). As a result, it is possible that there are some recessive lethal genes in the W chromosome.…”