The tunas could be called the 'ultimate teleosts'. They have a high percentage of muscle and a high percentage of that muscle is red muscle, the muscles are kept at above ambient temperatures by a counter current heat exchanger and the respiratory capabilities of these fish are accordingly high. The behavioral culmination of these characteristics is manifested in swimming speeds, which can be extraordinarily high, on a sustained, or a burst basis. One of the hottest and fastest tunas, the skipjack, was used in a study to determine (1) when each muscle is active (2) when and where the muscle heat is produced and (3) what the advantage of the hot musculature is to the animal.
Evidence from E. H. , histological, enzyme and metabolite studies suggest that the red muscle is qualitatively quite typical although its aerobic capacity is somewhat above that of other teleost red muscles. The white muscle has truely astounding anaerobic capabilities, but also displays an aerobic capacity not usually found in teleost white muscle.
Further examination of white muscle biochemical organization revealed a GP cycle which balances redox during the aerobic catabolism of glycogen and/or glucose. Both LDH (the terminal step in anaerobic glycolysis) and GPDH (the cytoplasmic arm of the GP cycle) are present in white muscle in high activities. Since these enzymes potentially compete for a common co-substrate, NADH, a tight control of these two enzymes seemed necessary to ensure mutual exclusive activity. Metabolite regulators of both enzymes were found which by affecting the ability of each enzyme to compete for NADH, channel carbon and hydrogen to lactate and C02 and H20 under anaerobic and aerobic conditions respectively. ,
The effect of temperature on metabolism was investigated and it is concluded that the stability rather than the absolute 'set point' of the body temperature is the more important feature. / Science, Faculty of / Zoology, Department of / Graduate
| Identifer | oai:union.ndltd.org:UBC/oai:circle.library.ubc.ca:2429/21153 |
| Date | January 1978 |
| Creators | Guppy, Michael |
| Source Sets | University of British Columbia |
| Language | English |
| Detected Language | English |
| Type | Text, Thesis/Dissertation |
| Rights | For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use. |
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