ISSN:
1432-136X
Keywords:
Hormonal regulation
;
Temperature acclimation
;
Catfish
;
Hepatocytes
;
Triiodothyronine
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary Protein synthesis (measured by 3H-leucine incorporation) by catfish hepatocytes in culture was enhanced when trace amounts of catfish serum were added. Serum from 15°C-acclimated fish was significantly more effective than serum from 25°C-acclimated fish. Total protein content of the cells was slightly diminished; DNA content was not altered. Added triiodothyronine (T3) significantly reduced protein synthesis by cultured hepatocytes, more at 25°C than at 15°C culture. Threshold concentration of T3 was 10−9 M. Removal of T3 from serum by exchange resin resulted in increased protein synthesis. Addition of T3 to that preparation decreased protein synthesis. The concentration of T3 in serum from 25°C-acclimated catfish is three times greater than the concentration in serum from 15°C-acclimated fish. Increase in protein synthesis after removal of T3 suggests that there is a blood-borne stimulating factor, more active in cold- than in warm-acclimated fish. The stimulating substance was present after dialysis (2000 Da cutoff) and was partially inactivated by heat. Insulin stimulated protein synthesis; salmon insulin was more effective than bovine insulin. Insulin content did not differ in serum from 15°C- and 25°C-fish. The effects of growth hormone and prolactin were equivocal or negative. The inhibitory effect of T3 may explain the reduction in metabolism during warm-acclimation. The nature of a stimulating hormone in cold acclimation is unknown.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00258755
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