Expression of a novel piscine growth hormone gene results in growth enhancement in transgenic tilapia (Oreochromis niloticus)

Citation
Ma. Rahman et al., Expression of a novel piscine growth hormone gene results in growth enhancement in transgenic tilapia (Oreochromis niloticus), TRANSGEN RE, 7(5), 1998, pp. 357-369
Citations number
44
Categorie Soggetti
Molecular Biology & Genetics
Journal title
TRANSGENIC RESEARCH
ISSN journal
09628819 → ACNP
Volume
7
Issue
5
Year of publication
1998
Pages
357 - 369
Database
ISI
SICI code
0962-8819(199809)7:5<357:EOANPG>2.0.ZU;2-H
Abstract
Several lines of transgenic G1 and G2 tilapia fish (Oreochromis niloticus) have been produced following egg injection with gene constructs carrying gr owth hormone coding sequences of fish origin. Using a construct in which an ocean pout antifreeze promoter drives a chinook salmon growth hormone gene , dramatic growth enhancement has been demonstrated, in which the mean weig ht of the 7 month old G2 transgenic fish is more than three fold that of th eir non transgenic siblings. Somewhat surprisingly G1 fish transgenic for a construct consisting of a sockeye salmon metallothionein promoter spliced to a sockeye salmon growth hormone gene exhibited no growth enhancement, al though salmon transgenic for this construct do show greatly enhanced growth . The growth enhanced transgenic lines were also strongly positive in a rad io-immuno assay for the specific hormone in their serum, whereas the non gr owth enhanced lines were negative. Attempts to induce expression from the m etallothionein promoter by exposing fish to increased levels of zinc were a lso unsuccessful. Homozygous transgenic fish have been produced from the ocean pout antifreez e/chinook salmon GH construct and preliminary trials suggest that their gro wth performance is similar to that of the hemizygous transgenics. No abnorm alities were apparent in the growth enhanced fish, although minor changes t o skull shape and reduced fertility were noted in some fish. There is also preliminary evidence for improved food conversion ratios when growth enhanc ed transgenic tilapia are compared to their non-transgenic siblings. The long term objective of this study is to produce lines of tilapia which are both growth enhanced and sterile, so offering improved strains of this important food fish for aquaculture.