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Genetic variation in the temperature dependence of liver microsomal cyp2e1 activity, within and between species of the viviparous fish Poeciliopsis
Author(s) -
Crivello Joseph F,
Schultz R Jack
Publication year - 1995
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.5620140101
Subject(s) - chlorzoxazone , biology , genotype , hybrid , cytochrome p450 , gene , zoology , genetics , enzyme , botany , cyp2e1 , biochemistry
The temperature dependence of liver microsomal CYP2E1 (cytochrome P450 2E1) activity was examined in selected genotypes of the viviparous fish Poeciliopsis Activity of this enzyme, as a function of incubation temperature, was determined by measuring 6 OH‐chlorzoxazone formation from chlorzoxazone, a specific CYP2E1 substrate Chlorzoxazone 6 hydroxylase activity was examined among five species of Poeciliopsis , as well as among nine genotypes within a species, P monacha Among Poeciliopsis genotypes, P monacha contained the greatest activity, 9 5 ± 1 5 U (where 1 U is defined as 1 μg 6 OH chlorzoxazone produced/min/mg protein, n = 6) with a temperature optimum ( T o ) of 25°C The lowest activity was in P occidentalis , 0 65 ± 0 11 U, with a T o of 27 to 28°C, P prolifica, P fasciata, P lucida , and P viriosa had intermediate levels of activities, 1 1 to 5 5 U, and T o from 25 to 31°C To determine if metabolic differences exist within species, enzyme activity was examined from nine genotypes of P monacha by comparing expression among P monacha‐lucida hybrids These hybrids were given identical paternal genomes of lucida but retained the original maternal monacha genomes sampled from wild gene pools The greatest activity was found in genotype T70 3 P Cw, 3 6 ± 0 1 U, at a T o of 29°C, and the lowest was in genotype SV73 7s, 0 40 ± 0 12 U, at a T o of 27°C The other naturally occurring genotypes, M65 24, M65–26 SV73 7v, as well as the laboratory produced synthetic hybrids, Syn4 and Syn5, had intermediate activities, 0 73 ± 0 38 to 2 1 ± 0 69 U, and T o of 25 to 27°C No hybrid had activity levels as high as the maternal parent, P monacha , and only one had a T o as low as either parent Apparently the genes involved in xenobiotic activity vary widely among the closely related species of Poeciliopsis but also within species suggesting that these phenotypes can be acted upon by natural selection