Smolt development in growth hormone transgenic Atlantic salmon (original) (raw)
Related papers
PLoS ONE, 2014
Should growth hormone (GH) transgenic Atlantic salmon escape, there may be the potential for ecological and genetic impacts on wild populations. This study compared the developmental rate and respiratory metabolism of GH transgenic and non-transgenic full sibling Atlantic salmon during early ontogeny; a life history period of intense selection that may provide critical insight into the fitness consequences of escaped transgenics. Transgenesis did not affect the routine oxygen consumption of eyed embryos, newly hatched larvae or first-feeding juveniles. Moreover, the timing of early life history events was similar, with transgenic fish hatching less than one day earlier, on average, than their non-transgenic siblings. As the start of exogenous feeding neared, however, transgenic fish were somewhat developmentally behind, having more unused yolk and being slightly smaller than their non-transgenic siblings. Although such differences were found between transgenic and non-transgenic siblings, family differences were more important in explaining phenotypic variation. These findings suggest that biologically significant differences in fitness-related traits between GH transgenic and non-transgenic Atlantic salmon were less than family differences during the earliest life stages. The implications of these results are discussed in light of the ecological risk assessment of genetically modified animals.
Aquaculture, 2012
Several different transgenic growth hormone (GH) gene constructs have been used to obtain accelerated growth in salmonids. However, there have been limited direct comparisons of these constructs in terms of the ability to achieve maximal growth in fish. We examined the effect of promoter type (sockeye salmon metallothionein-B or histone 3) fused to a growth hormone-1 coding region from the same species (OnMTGH1 and OnH3GH1 constructs respectively) on growth and plasma growth hormone (GH) and insulin-like growth factor-I (IGF-I) in multiple strains of GH transgenic coho salmon (Oncorhynchus kisutch). Salmon transgenic for the OnMTGH1 construct had consistently greater overall weight than those containing the OnH3GH1 construct, although both groups possessed greatly accelerated growth over non-transgenic fish. However, there were strong strain effects, where some OnH3GH1 strains had similar weight to OnMTGH1 strains while others did not. Triploidy diminished growth acceleration and decreased condition factors in both a fast growing MT strain and slower growing H3 strain. Plasma GH levels did not correlate to weight in transgenic strains, and all but one transgenic strain had plasma GH levels similar to equal sized non-transgenic fish. In contrast, plasma IGF-I content correlated well to size in transgenic strains. The mechanism by which accelerated growth in transgenic fish is obtained appears to be due in part to an upregulation of GH action through increased circulating IGF-I levels, and promoter-type appears to influence potential for growth.
Marine Biotechnology
Growth hormone (GH) transgenic fish often exhibit remarkable transformations in growth rate and other phenotypes relative to wild-type. The 5750A transgenic coho salmon strain exhibits strong sexually dimorphic growth, with females possessing growth stimulation at a level typical of that seen for both sexes in other strains harbouring the same gene construct (e.g. M77), while males display a modest level of growth stimulation. GH mRNA levels were significantly higher in females than in males of the 5750A strain but equivalent in the M77 strain, indicating sex and transgene insertion locus altered transgene expression. We found that acute estradiol treatments did not influence GH expression in either strain (5750A and M77) or the transgene promoter (metallothionein-B), suggesting that estradiol level was not a significant factor influencing transgene activity. The feminization of XX and XY fish of the 5750A and M77 strains generated all-female groups and resulted in equalized growth ...
Growth, viability and genetic characteristics of GH transgenic coho salmon strains
Aquaculture, 2004
Transgenic coho salmon strains containing an all-salmon growth hormone (GH) gene construct (OnMTGH1) have been examined. The transgene utilized is comprised of the metallothionein-B promoter driving the expression of the type-I growth hormone gene from sockeye salmon. Transgene DNA is integrated into the salmon genome, but is transmitted at low frequency from founder transgenic animals consistent with late integration following microinjection resulting in mosaic animals, whereas subsequent generations transmit transgene DNA as a stable Mendelian trait. Different families established from separate founder animals yield lines with unique growth characteristics suggesting important site-of-integration effects on transgene expression. Growth enhancement of transgenic salmon is initiated early, with advanced hatch timing but occurring also throughout the life history, particularly during the early phase in fresh water. GH transgenic fish showed precocious smoltification and onset of sexual maturation, but approximately normal adult body size, indicating that compression of the normal coho salmon life history is occurring. The viability of diploid GH transgenic salmon ranges from reductions to greater than that of controls among strains, and triploid transgenic animals had normal viability relative to diploid transgenic salmon. Triploid transgenic salmon display a reduction in growth rate relative to transgenic diploids, but are still significantly growth enhanced compared with nontransgenic controls. The distinct phenotypic characteristics of GH transgenic families suggest that evaluation for aquaculture and for risk assessments requires examination of strains on a case-by-case basis. Furthermore, strong effects of size at maturity in culture conditions were observed for nontransgenic wild strain coho salmon which were not apparent in GH transgenic salmon,
PLoS ONE, 2014
Growth hormone (GH) transgenes can significantly accelerate growth rates in fish and cause associated alterations to their physiology and behaviour. Concern exists regarding potential environmental risks of GH transgenic fish, should they enter natural ecosystems. In particular, whether they can reproduce and generate viable offspring under natural conditions is poorly understood. In previous studies, GH transgenic salmon grown under contained culture conditions had lower spawning behaviour and reproductive success relative to wild-type fish reared in nature. However, wild-type salmon cultured in equal conditions also had limited reproductive success. As such, whether decreased reproductive success of GH transgenic salmon is due to the action of the transgene or to secondary effects of culture (or a combination) has not been fully ascertained. Hence, salmon were reared in large (350,000 L), semi-natural, seawater tanks (termed mesocosms) designed to minimize effects of standard laboratory culture conditions, and the reproductive success of wild-type and GH transgenic coho salmon from mesocosms were compared with that of wild-type fish from nature. Mesocosm rearing partially restored spawning behaviour and success of wild-type fish relative to culture rearing, but remained lower overall than those reared in nature. GH transgenic salmon reared in the mesocosm had similar spawning behaviour and success as wild-type fish reared in the mesocosm when in full competition and without competition, but had lower success in maleonly competition experiments. There was evidence of genotype6environmental interactions on spawning success, so that spawning success of transgenic fish, should they escape to natural systems in early life, cannot be predicted with low uncertainty. Under the present conditions, we found no evidence to support enhanced mating capabilities of GH transgenic coho salmon compared to wild-type salmon. However, it is clear that GH transgenic salmon are capable of successful spawning, and can reproduce with wild-type fish from natural systems.
Aquaculture, 2000
Transgenic coho salmon containing a growth hormone GH gene construct have been examined for their hormone levels and ability to osmoregulate in sea water. Relative to their Ž . smaller nontransgenic siblings age controls , GH-transgenic coho precociously develop external phenotypes and hypo-osmoregulatory ability typical of smolts. Specific growth rates of the transgenic coho were approximately 2.7-fold higher than older nontransgenic animals of similar size, and 1.7-fold higher than their nontransgenic siblings. GH levels were increased dramatically Ž . 19.3-to 32.1-fold relative to size control salmon, but IGF-I levels were only modestly affected, being slightly enhanced in one experiment and slightly reduced in another. Insulin levels in transgenic animals did not differ from size controls, but were higher than nontransgenic siblings, and thyroxine levels in transgenic animals were intermediate between levels found in size and age controls. The homeostatic controls of, and interactions among, these hormones are discussed with respect to their effects on growth and osmoregulation. q
General and Comparative Endocrinology, 2000
Earlier studies have established that increased daylength increases plasma growth hormone (GH) levels during spring smoltification of yearling Atlantic salmon. Recently, the Atlantic salmon aquaculture industry has started the production of underyearling ("summer") smolts. This involves fast juvenile growth on continuous light (24L), the transfer of juveniles over 8 cm in length to short day (12L) for 6 weeks in the summer, followed by transfer to 24L for another 6 weeks before transfer to seawater in late October. Three groups were studied in fresh water from July to the following May in order to elucidate the GH response to this photoperiod manipulation: one group was kept on 24L throughout (long-day group), while the other two groups were exposed to short day from July 15th. Of these, one was brought back onto long day on September 1st (winter group) while the other was kept on short day (short-day group). Plasma GH levels of the long-day group were around 1.6 ng/ml throughout the study. The short-day transfer suppressed GH levels to 0.7 ng/ml within 2 weeks (short-day and winter groups). The long-day transfer (winter group) increased GH levels to 11 ng/ml within 3 weeks, and this elevation of GH levels was sustained for about 3 months, before declining to pretreatment levels. The study demonstrates that underyearling Atlantic salmon react to increased daylength in a way similar to traditional yearling smolts.
Isolation, characterization and comparison of Atlantic and Chinook salmon growth hormone 1 and 2
BMC Genomics, 2008
Background: Growth hormone (GH) is an important regulator of skeletal growth, as well as other adapted processes in salmonids. The GH gene (gh) in salmonids is represented by duplicated, non-allelic isoforms designated as gh1 and gh2. We have isolated and characterized gh-containing bacterial artificial chromosomes (BACs) of both Atlantic and Chinook salmon (Salmo salar and Oncorhynchus tshawytscha) in order to further elucidate our understanding of the conservation and regulation of these loci.
General and Comparative Endocrinology, 1995
Earlier studies have established that increased daylength increases plasma growth hormone (GH) levels during spring smoltification of yearling Atlantic salmon. Recently, the Atlantic salmon aquaculture industry has started the production of underyearling ("summer") smolts. This involves fast juvenile growth on continuous light (24L), the transfer of juveniles over 8 cm in length to short day (12L) for 6 weeks in the summer, followed by transfer to 24L for another 6 weeks before transfer to seawater in late October. Three groups were studied in fresh water from July to the following May in order to elucidate the GH response to this photoperiod manipulation: one group was kept on 24L throughout (long-day group), while the other two groups were exposed to short day from July 15th. Of these, one was brought back onto long day on September 1st (winter group) while the other was kept on short day (short-day group). Plasma GH levels of the long-day group were around 1.6 ng/ml throughout the study. The short-day transfer suppressed GH levels to 0.7 ng/ml within 2 weeks (short-day and winter groups). The long-day transfer (winter group) increased GH levels to 11 ng/ml within 3 weeks, and this elevation of GH levels was sustained for about 3 months, before declining to pretreatment levels. The study demonstrates that underyearling Atlantic salmon react to increased daylength in a way similar to traditional yearling smolts.