Document Detail

Cardiorespiratory modifications, and limitations, in post-smolt growth hormone transgenic Atlantic salmon Salmo salar.
MedLine Citation:
PMID:  16547302     Owner:  NLM     Status:  MEDLINE    
In recent years, there has been a great deal of interest in how growth hormone (GH) transgenesis affects fish physiology. However, the results of these studies are often difficult to interpret because the transgenic and non-transgenic fish had very different environmental/rearing histories. This study used a stable line of size-matched GH Atlantic salmon (Salmo salar) that were reared in a shared tank with controls (at 10 degrees C, for approximately 9 months) to perform a comprehensive examination of the cardiorespiratory physiology of GH transgenic salmon, and serves as a novel test of the theory of symmorphosis. The GH transgenic salmon had a 3.6x faster growth rate, and 21 and 25% higher values for mass-specific routine and standard oxygen consumption (M(O(2))), respectively. However, there was no concurrent increase in their maximum M(O(2)), which resulted in them having an 18% lower metabolic scope and a 9% reduction in critical swimming speed. This decreased metabolic capacity/performance was surprising given that the transgenics had a 29% larger heart with an 18% greater mass-specific maximum in situ cardiac output, a 14% greater post-stress blood haemoglobin concentration, 5-10% higher red muscle and heart aerobic enzyme (citrate synthase or cytochrome oxidase) activities, and twofold higher resting and 1.7x higher post-stress, catecholamine levels. However, gill surface area was the only cardiorespiratory parameter that was not enhanced, and our data suggest that gill oxygen transfer may have been limiting. Overall, this research: (1) shows that there are significant metabolic costs associated with GH transgenesis in this line of Atlantic salmon; (2) provides the first direct evidence that cardiac function is enhanced by GH transgenesis; (3) shows that a universal upregulation of post-smolt (adult) GH transgenic salmon cardiorespiratory physiology, as suggested by symmorphosis, does not occur; and (4) supports the idea that whereas differences in arterial oxygen transport (i.e. cardiac output and blood oxygen carrying capacity) are important determinants of inter-specific differences in aerobicity, diffusion-limited processes must be enhanced to achieve substantial intra-specific improvements in metabolic and swimming performance.
E J Deitch; G L Fletcher; L H Petersen; I A S F Costa; M A Shears; W R Driedzic; A K Gamperl
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of experimental biology     Volume:  209     ISSN:  0022-0949     ISO Abbreviation:  J. Exp. Biol.     Publication Date:  2006 Apr 
Date Detail:
Created Date:  2006-03-20     Completed Date:  2006-06-13     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0243705     Medline TA:  J Exp Biol     Country:  England    
Other Details:
Languages:  eng     Pagination:  1310-25     Citation Subset:  IM    
Ocean Sciences Centre, Memorial University of Newfoundland, St John's, Newfoundland A1C 5S7, Canada.
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MeSH Terms
Animals, Genetically Modified / physiology*
Citrate (si)-Synthase / metabolism
Electron Transport Complex IV / metabolism
Erythrocytes / chemistry,  cytology
Gills / physiology*
Growth Hormone / genetics*,  physiology
Heart / anatomy & histology,  physiology*
Hemoglobins / analysis
Hydrocortisone / blood
Oxygen Consumption
Salmo salar / genetics,  growth & development,  physiology*
Swimming / physiology
Reg. No./Substance:
0/Hemoglobins; 50-23-7/Hydrocortisone; 9002-72-6/Growth Hormone; EC Transport Complex IV; EC (si)-Synthase

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