Family-specific differences in growth rate and hepatic gene expression in triploid growth hormone (GH) transgenic Atlantic salmon (Salmo salar L.)

Xu, Qingheng (2012) Family-specific differences in growth rate and hepatic gene expression in triploid growth hormone (GH) transgenic Atlantic salmon (Salmo salar L.). Masters thesis, Memorial University of Newfoundland.

[English] PDF (Migrated (PDF/A Conversion) from original format: (application/pdf)) - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (70MB) [English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. (Original Version)

Abstract

Growth hormone transgenic (GHTg) Atlantic salmon have enhanced growth when compared to their non-transgenic counterparts, and this trait is beneficial for aquaculture production. However, there are concerns regarding the potential impacts of transgenic fish on wild populations. The culture of sterile triploid GH transgenic (3NGHTg) Atlantic salmon would prevent interbreeding of transgenic fish and wild stocks, thus minimizing environmental impacts. Generally, the growth performance of triploid salmon relative to diploid siblings remains an area of investigation. Growth rate of 3NGHTg Atlantic salmon families were found to significantly vary between families in a breeding program. In order to identify gene expression correlates of enhanced growth in 3NGHTg Atlantic salmon, a functional genomics approach (32K cDNA microarrays followed by QPCR) was used to identify and validate liver transcripts that are differentially expressed between two fast-growing 3NGHTg Atlantic salmon families (AS11, AS26) and one slowgrowing 3NGHTg Atlantic salmon family (AS25). Of 687 reproducibly informative microarray features, 143 features (116 more highly expressed in fast-growing, and 27 more highly expressed in slow-growing) were identified in the AS11 vs. AS25 microarray study, while 544 features (442 more highly expressed in fast-growing and 102 more highly expressed in slow-growing) were identified in the AS26 vs. AS25 microarray study. In order to identify growth-relevant transcripts that were consistently differentially expressed between fast-growing and slow-growing 3NGHTg families, the AS11 vs. AS25 and AS26 vs. AS25 microarray gene lists were further analyzed using Venn diagrams. Forty microarray features (39 associated with fast growth and 1 associated with slow growth) were present in both microarray comparisons. The expression levels of 15 microarray-identified transcripts were studied using QPCR with individual RNA samples to validate the microarray results and to study biological variability of transcript expression. The QPCR results agreed with the microarray results for 12 of 13 putative fast-growth associated transcripts, but QPCR did not validate the microarray results for 2 putative slow-growth associated transcripts. Many of the 39 microarray features that were consistently associated with fast-growing 3NGHTg salmon (including ACBP, APOAI, APOAIV, B2M, D5DP, FTM, GAPDH, and NUPR1) were involved in carbohydrate, lipid, and amino acid metabolism, iron homeostasis and oxygen transport, and immune-or stress-related responses. The results of this study increase our knowledge of family-specific impacts on growth rate and hepatic gene expression in 3NGHTg Atlantic salmon. In addition, this study provides a suite of rapid growth rate associated transcripts that may lead to the development of molecular markers (e.g. intronic, exonic or regulatory region SNPs) for the selection of GHTg Atlantic salmon broodstock that will give rise to sterile triploids of desired growth performance for future commercial applications.

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