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Maintenance of the alcohol dehydrogenase polymorphism in Tiger Salamanders, II. Differences in biochemical function among allozymes
Author(s) -
Carter P. A.,
Mitton J. B.,
Kocher T. D.,
Coelho J. R.
Publication year - 2000
Publication title -
functional ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.272
H-Index - 154
eISSN - 1365-2435
pISSN - 0269-8463
DOI - 10.1046/j.1365-2435.2000.00390.x
Subject(s) - biology , alcohol dehydrogenase , acetaldehyde , oxygen , genotype , loss of heterozygosity , ethanol , genetics , tiger salamander , locus (genetics) , isozyme , allele , biochemistry , enzyme , gene , ecology , chemistry , organic chemistry , larva
1. Previous studies of Tiger Salamanders demonstrated that variation in alcohol dehydrogenase (Adh) contributed significantly to associations between multilocus heterozygosity and oxygen consumption traits, and that Adh variation was associated with levels of pond‐oxygen and metamorphic ability in extreme oxygen environments. Here Adh allozymes are characterized kinetically, and relationships between Adh and oxygen‐related physiological traits (ATP/Hb, 2,3‐DPG/Hb) are measured. 2. Kinetic differences were measured among Adh allozymes in the acetaldehyde‐to‐ethanol direction: k cat / K m ratios (the catalytic constant divided by the Michaelis–Menton constant) were significantly higher in Adh‐SF than the other two genotypes, and in Adh‐SS compared with Adh‐FF. No significant differences were measured in the ethanol to acetaldehyde direction. 3. Adh‐SS had a significantly higher ATP/Hb than Adh‐FF, with the Adh‐SF intermediate. In addition, a significant interaction between Hb and body mass was measured, such that Adh‐FF showed a negative relationship between Hb concentration and body mass while the other two genotypes showed a positive relationship. 4. These results are consistent with the hypothesis that variation at the Adh locus has adaptive and physiological significance, and that functional differences among Adh allozymes partly explain significant associations between multilocus genotype and organismal traits.