Integration mechanisms of transgenes and population fitness of GH transgenic fish

Abstract

It has been more than 20 years since the first batch of transgenic fish was produced. Five stable germ-line transmitted growth hormone (GH) transgenic fish lines have been generated. This paper reviews the mechanisms of integration and gene targeting of the transgene, as well as the viability, reproduction and transgenic approaches for the reproductive containment of GH-transgenic fish. Further, we propose that it should be necessary to do the following studies, in particularly, of the breeding of transgenic fish: to assess the fitness of transgenic fish in an aqueous environment with a large space and a complex structure; and to develop a controllable on-off strategy of reproduction in transgenic fish. transgene, integration mechanism, GH transgenic fish, population fitness Citation:Hu [6,7]. In cooperation with Hunan Normal University, we produced a transgenic triploid fish with a growth rate that is 15% faster than that of the control carp, with a forage utilization rate increased by 11.1%. The transgenic triploid fish is completely sterile [8]. Such completely sterile transgenic triploid carp such as the all-fish GH transgenic carp may be suitable for industrialized conditions. The US Food and Drug Administration (FDA) is evaluating the ecological effects of current and potential uses of the field release of GH transgenic Atlantic salmon, which would promote the commercial farming of transgenic fish. No transgenic animals have been released into a natural environment for commercialized cultivation as food. Transgenic fish would be the breakthrough model as the first commercial farming transgenic animal. We review the mechanisms of integration and controllable regulatory expression of transgenes and the population fitness assessments of GH transgenic fish. We will conclude by providing suggestions for the thorough study of genetic engineering in breeding fish for potential commercial uses.

The integration characteristics of the exogenous growth hormone gene in a transgenic common carp (Cyprinus carpio L.) with fast-growth performance

“…Our real-time PCR results showed that there were three exogenous GH genes in the hemizygous transgenic common carp genome. Based on further analysis of the flanking sequences at the integration site, we confirmed that the copy number of the hemizygous transgenic common carp was in fact just two, which supports the hypothesis that high expression is associated with low copy number [3].…”

“…Compared with distant hybridization, transgenic techniques show greater perspective in animal breed improvement because of its illimitation in species and desired traits [1], although the potential ecological risk of transgene needs to be hedged by some measures such as reproduction control [2][3][4]. The development of fish breeding and aquaculture will accelerate once the genes associated with economically important traits in fishes are discovered and introduced into target species by transgenic techniques [5].…”

“…In this present study, we aimed to verify the integration site and copy numbers of the exogenous GH gene in the transgenic common carp line. Characterization of the GH integration site may offer an improved understanding of the mechanism of the transgene integration, as well as providing reference data to evaluate the ecological risks associated with GH-transgenic common carp [2,3].…”

Molecular basis and genetic improvement of economically important traits in aquaculture animals

“…During this century, the cloned zebrafish were obtained by nuclear transfer from long-term-cultured cells [35], and the cytoplasmic impact was analyzed in cross-genus cloned fish derived from transgenic common carp (Cyprinus carpio) nuclei and goldfish (Carassius auratus) enucleated eggs [36]. Moreover, some differentially expressed genes were identified from the cloned zebrafish embryos at the dome stage [37], and the critical developmental stages for high integration efficiency were determined in zebrafish [38,39]. Stem cell culture and application have been rapidly developed in model fishes of medaka and zebrafish [40,41], and some stem cell technologies, such as gene targeting, germ cell transplantation and semi-cloning by nuclear transfer, have been successfully formed because of specific potentials of fish germ stem cells and embryonic stem cells [42,43].…”

Research advances in animal distant hybridization

“…The laboratory of Zhu ZuoYan has made outstanding contributions in this area [102,103]. To minimize the shortcomings of artificially induced triploid fish and control potential risks posed by transgenic fish introduction, the Institute of Hydrobiology of the Chinese Academy of Sciences has joined with Hunan Normal University to carry out hybridization experiments between Cyprinus carpio and 4nAT; a transgenic triploid fish showing fast growth, efficient feed conversion, and good breeding traits has been developed via hybridization of fish with differing ploidy levels [104].…”