Transfer of growth hormone (GH) transgenes into Arctic charr ( Salvelinus alpinus L.) : I. Growth response to various GH constructs

Abstract

Four constructs containing salmonid growth hormone (GH) genes were transferred to Arctic charr ( Salvelinus alpinus L.). Cytomegalovirus (CMV) and piscine metallothionein B (OnMT) and histone 3 (OnH3) promoters connected to sockeye salmon growth hormone 1 gene (OnGH1) were used for ectopic expression, and Atlantic salmon growth hormone 2 gene with 5′flanking region (SsGH2) was tested for pituitary-specific expression. Charr carrying the OnGH1 constructs showed a dramatic increase in growth rate. The 10-month old transformed fish were 14-fold heavier than control siblings. The ability of the CMVGH1 construct to promote growth was greater than that obtained in fish with piscine promoters. Analysis of individual growth curves of charr carrying the OnH3GH1 transgene indicated a stable ratio of specific growth rates in transformed and control fish regardless of fish size. No alteration in growth performance was found in fish carrying the SsGH2 transgene. There was evidence that the transformed rainbow trout ( Oncorhynchus mykiss) were unable to produce SsGH2 mRNA in their pituitary glands. The presence of the transgene in various tissues was examined in trout to evaluate the reliability of one-tissue sampling.