|
| |
|
|
|
|
||||
| Home Help Feedback Subscriptions Archive Search Table of Contents | ||||
First published online March 17, 2006
Journal of Experimental Biology 209, 1310-1325 (2006)
Published by The Company of Biologists 2006
doi: 10.1242/jeb.02105
Cardiorespiratory modifications, and limitations, in post-smolt growth hormone transgenic Atlantic salmon Salmo salar
Ocean Sciences Centre, Memorial University of Newfoundland, St John's, Newfoundland A1C 5S7, Canada
* Author for correspondence (e-mail: kgamperl{at}mun.ca)
Accepted 18 January 2006
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°C, for
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 (
O2),
respectively. However, there was no concurrent increase in their maximum
O2, 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.
Key words: transgenic, symmorphosis, heart, oxygen transport, critical swimming speed, cardiovascular function, stress, catecholamines, cortisol, Atlantic salmon, Salmo salar
This article has been cited by other articles:
|
|
 |
|
  H. M. Levesque, M. A. Shears, G. L. Fletcher, and T. W. Moon Myogenesis and muscle metabolism in juvenile Atlantic salmon (Salmo salar) made transgenic for growth hormone J. Exp. Biol., January 1, 2008; 211(1): 128 - 137. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. C. Mendonca, A. G. Genge, E. J. Deitch, and A. K. Gamperl Mechanisms responsible for the enhanced pumping capacity of the in situ winter flounder heart (Pseudopleuronectes americanus) Am J Physiol Regulatory Integrative Comp Physiol, November 1, 2007; 293(5): R2112 - R2119. [Abstract] [Full Text] [PDF]
|
|
