Genetic manipulation of olive flounder
Paralichthys olivaceus.
Zhang P., Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China

Abstract

Genetic manipulation by using gene transfer and gynogenesis techniques was performed to produce fast-growing transgenic flounder and the all-female flounder, Paralichthys olivaceus. An all-fish growth hormone gene construct containing the ocean pout antifreeze protein gene promoter and the chinook salmon growth hormone gene cDNA was introduced into the fertilized flounder eggs by electroporation. Integration rate of 33% was detected by PCR-electrophoresis analysis of the genomic DNA samples from 1-month old electroporated juvenile fish. Western-immunoblot analysis of the serum samples from 5-month old transgenic fish showed a expression rate of 27.2%. The average body weight of transgenic fish was 25% larger than that of the control. Cold shock method was used to induce gynogenesis of the flounder eggs. The inducing condition tests showed that the high inducing rate of 90% was obtained from eggs at a stage of 5 minutes after fertilization, treated in 2? sea water bath for 45 minutes. The chromosome haploidy detection and the morphology observation of hatched fry were used to estimate the gynogenesis inducing efficiency. The young fish developed from embryos of gynogenesis were treated with methyltestosterone at the age of one month age 70 days. The pseudo males produced by this sex conversion treatment were cultured for further all-female flounder production.

Key words: genetic manipulation, gene transfer, growth hormone gene, gynogenesis, sex conversion