Inhibition of glucosephosphate isomerase allozymes of the mosquitofish, Gambusia holbrooki, by mercury

Journal Article · Sat Jan 01 00:00:00 EST 1994 · Environmental Toxicology and Chemistry; (United States)

DOI:https://doi.org/10.1897/1552-8618(1994)13[9:IOGIAO]2.0.CO;2· OSTI ID:5429854

Kramer, V J; Newman, M C ^[1]

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1. Univ. of Georgia, Aiken, SC (United States). Savannah River Ecology Lab.

Frequencies of allozyme genotypes are being used as population-level indicators of environmental heavy-metal contamination. A genotype of glucose phosphate isomerase, Gpi-2[sup 38/38], of mosquitofish (Gambusia holbrooki) has been identified as mercury-sensitive in an acute toxicity assay. Partially purified preparations of GPI-2 38/38 and GPI-2 100/100 were assayed to determine differences in maximum gluconeogenic reaction velocity at seven mercury (added as HgCl[sub 2]) concentrations, 15 to 960 nM Hg. Log-Probit analysis of the inhibition curves indicated that the log (IC50) (log[sub 10] of the Hg concentration causing a 50% reduction in reaction velocity) for GPI-2 100/100 initial uninhibited reaction velocity was greater than that of GPI-2 38/38. Although the mechanism of inhibition was not experimentally determined, under the assumption of noncompetitive interaction between Hg and GPI-2, the inhibitor dissociation constants (95% asymptotic C.I.) for GPI-2 100/100 and GPI-2 38/38 were estimated from the log (IC50) as 204 nM Hg (155---269 nM Hg) and 479 nM Hg (363-617 nM Hg), respectively. These results suggested that Hg susceptibility related to the Gpi-2[sup 38/38] genotype in acute toxicity assays was likely not due to enhanced Hg inhibition of GPI-2 38/38.

• OSTI ID: 5429854
• Journal Information: Environmental Toxicology and Chemistry; (United States), Vol. 13:1; ISSN 0730-7268
• Country of Publication: United States
• Language: English

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