Myogenesis and muscle metabolism in juvenile Atlantic salmon (Salmo salar) made transgenic for growth hormone (original) (raw)
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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.
Proceedings of The National Academy of Sciences, 2009
Domestication has been extensively used in agricultural animals to modify phenotypes such as growth rate. More recently, transgenesis of growth factor genes [primarily growth hormone (GH)] has also been explored as a rapid approach to accelerating performance of agricultural species. Growth rates of many fishes respond dramatically to GH gene transgenesis, whereas genetic engineering of domestic mammalian livestock has resulted in relatively modest gains. The most dramatic effects of GH transgenesis in fish have been seen in relatively wild strains that have undergone little or no selection for enhanced growth, whereas genetic modification of livestock necessarily has been performed in highly domesticated strains that already possess very rapid growth. Such fast-growing domesticates may be refractory to further stimulation if the same regulatory pathways are being exploited by both genetic approaches. By directly comparing gene expression in wild-type, domestic, and GH transgenic strains of coho salmon, we have found that domestication and GH transgenesis are modifying similar genetic pathways. Genes in many different physiological pathways show modified expression in domestic and GH transgenic strains relative to wild-type, but effects are strongly correlated. Genes specifically involved in growth regulation (IGF1, GHR, IGF-II, THR) are also concordantly regulated in domestic and transgenic fish, and both strains show elevated levels of circulating IGF1. Muscle expression of GH in nontransgenic strains was found to be elevated in domesticated fish relative to wild type, providing a possible mechanism for growth enhancement. These data have implications for genetic improvement of existing domesticated species and risk assessment and regulation of emerging transgenic strains.
Smolt development in growth hormone transgenic Atlantic salmon
Aquaculture, 1998
. Growth hormone transgenic Atlantic salmon Salmo salar produced using a gene construct Ž . Ž comprised of an antifreeze protein AFP gene promoter from ocean pout Macrozoarces . Ž. Ž americanus and the growth hormone GH gene from chinook salmon Oncorhynchus . tshawytscha were used for this study of smolt development. An F generation of these transgenic 2 salmon was initiated in November 1995 using milt from a transgenic F male and eggs from a ) Corresponding author 1 For the Department of Fisheries and Oceans, Government of Canada. 0044-8486r98r$ -see front matter Crown Copyright q 1998 Published by Elsevier Science B.V. Ž . PII: S 0 0 4 4 -8 4 8 6 9 8 0 0 3 4 8 -2 ( ) R.L. Saunders et al.r Aquaculture 168 1998 177-193 178 It appears that GH transgenic Atlantic salmon can be reared under temperature and photoperiod regimes which optimize growth, but which would inhibit normal smolt development and post-smolt performance of non-transgenic salmon. Crown
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.
Endocrine effects of growth hormone overexpression in transgenic coho salmon
General and Comparative Endocrinology, 2008
Non-transgenic (wild-type) coho salmon (Oncorhynchus kisutch), growth hormone (GH) transgenic salmon (with highly elevated growth rates), and GH transgenic salmon pair fed a non-transgenic ration level (and thus growing at the non-transgenic rate) were examined for plasma hormone concentrations, and liver, muscle, hypothalamus, telencephalon, and pituitary mRNA levels. GH transgenic salmon exhibited increased plasma GH levels, and enhanced liver, muscle and hypothalamic GH mRNA levels. Insulin-like growth factor-I (IGF-I) in plasma, and growth hormone receptor (GHR) and IGF-I mRNA levels in liver and muscle, were higher in fully fed transgenic than non-transgenic fish. GHR mRNA levels in transgenic fish were unaffected by ration-restriction, whereas plasma GH was increased and plasma IGF-I and liver IGF-I mRNA were decreased to wild-type levels. These data reveal that strong nutritional modulation of IGF-I production remains even in the presence of constitutive ectopic GH expression in these transgenic fish. Liver GHR membrane protein levels were not different from controls, whereas, in muscle, GHR levels were elevated approximately 5-fold in transgenic fish. Paracrine stimulation of IGF-I by ectopic GH production in non-pituitary tissues is suggested by increased basal cartilage sulphation observed in the transgenic salmon. Levels of mRNA for growth hormone-releasing hormone (GHRH) and cholecystokinin (CCK) did not differ between groups. Despite its role in appetite stimulation, neuropeptide Y (NPY) mRNA was not found to be elevated in transgenic groups.
General and Comparative Endocrinology, 2012
To examine the relative growth, endocrine, and gene expression effects of growth hormone (GH) transgenesis vs. GH protein treatment, wild-type non-transgenic and GH transgenic coho salmon were treated with a sustained-release formulation of recombinant bovine GH (bGH; Posilac™). Fish size, specific growth rate (SGR), and condition factor (CF) were monitored for 14 weeks, after which endocrine parameters were measured. Transgenic fish had much higher growth, SGR and CF than non-transgenic fish, and bGH injection significantly increased weight and SGR in non-transgenic but not transgenic fish. Plasma salmon GH concentrations decreased with bGH treatment in non-transgenic but not in transgenic fish where levels were similar to controls. Higher GH mRNA levels were detected in transgenic muscle and liver but no differences were observed in GH receptor (GHR) mRNA levels. In non-transgenic pituitary, GH and GHR mRNA levels per mg pituitary decreased with bGH dose to levels seen in transgenic salmon. Plasma IGF-I was elevated with bGH dose only in non-transgenic fish, while transgenic fish maintained an elevated level of IGF-I with or without bGH treatment. A similar trend was seen for liver IGF-I mRNA levels. Thus, bGH treatment increased fish growth and influenced feedback on endocrine parameters in nontransgenic but not in transgenic fish. A lack of further growth stimulation of GH transgenic fish suggests that these fish are experiencing maximal growth stimulation via GH pathways.
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
2005
This paper reports on the effect of administration of mammalian growth hormone (GH) on muscle protein synthesis as measured in white muscle using the phenylalanine flooding technique. The effect of exogenous GH was compared with that of insulin and prolactin, and with endogenous GH.The rate of protein synthesis in white muscle of rainbow trout 6 h after the injection of bovine GH or bovine insulin was twice (2.6 and 2.9% d−1) that of the control saline-injected fish (1.2% d−1). A metabolic effect of GH, as observed with insulin, is suspected.The rates of change in body weight and body length and the fractional rate of protein synthesis in muscle of rainbow trout were enhanced by mammalian GH administration. The effect of GH on muscle RNA/protein ratios was not significant. An opposite effect of antibodies against salmon GH (Lebailet al. 1989) on growth rate and muscle protein synthesis rate was found in rainbow trout. It is suggested that the effects of exogenous and endogenous GH o...
Aquaculture, 2002
The aim of this study was to compare metabolic and digestive enzyme activities in fish with different growth capacities using growth hormone transgenic and nontransgenic coho salmon (Oncorhynchus kisutch) as a model system. The following enzyme activities were measured: trypsin and chymotrypsin in pyloric caeca, alkaline phosphatase in intestine, pyruvate kinase (PK), lactate dehydrogenase (LDH) and citrate synthase (CS) in gills and white muscle. Transgenic salmon showed higher LDH activity in muscle and PK activities in muscle and gills, whereas chymotrypsin activity in pyloric caeca was higher in the control group. No significant differences were observed between transgenic and control groups for CS, trypsin and alkaline phosphatase activities. The small or no differences observed in this study suggests that the enzyme activities measured were not related to the high growth rate of the transgenic coho salmon. D
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 ...