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Changes in leucine transport activity in Chironomus riparius larvae after short‐term exposure to potassium dichromate and fenitrothion
Author(s) -
Forcella Matilde,
Berra Elisa,
Giacchini Roberto,
Hanozet Giorgio M.,
Parenti Paolo
Publication year - 2004
Publication title -
archives of insect biochemistry and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.576
H-Index - 66
eISSN - 1520-6327
pISSN - 0739-4462
DOI - 10.1002/arch.10127
Subject(s) - chironomus riparius , potassium dichromate , fenitrothion , biology , larva , potassium , leucine , toxicology , ecology , zoology , botany , pesticide , biochemistry , chironomidae , amino acid , chemistry , inorganic chemistry , organic chemistry
The effect of sublethal concentrations of potassium dichromate and fenitrothion on sodium‐leucine cotransport in brush border membrane vesicles from Chironomus riparius larvae has been investigated. Exposure to potassium dichromate and fenitrothion caused a dose‐ and time‐dependent inhibition of leucine uptake. Transport inhibition is easily detectable at doses 100‐fold lower than LD 50 . Kinetic experiments showed that inhibition was mainly caused by a decrease of the Vmax (680 ± 53 vs. 382 ± 23 and 555 ± 27 nmol/15s/mg protein in control and exposed larvae to K 2 Cr 2 O 7 and fenitrothion, respectively). Inhibition is possibly related to a variation of sodium ions permeability as evidenced by increased membrane lipid peroxidation. Appropriate control experiments ruled out that the observed differences could be due to changes in general features of membrane preparations. Transport inhibition observed in larvae exposed to potassium dichromate was accompanied by changes in ascorbate peroxidase and dehydroascorbate reductase activities, whereas those exposed to fenitrothion displayed an increase in transaminase activity. The possible value of leucine uptake as biochemical biomarker is briefly discussed. Arch. Insect Biochem. Physiol. 55:90–101, 2004. © 2004 Wiley‐Liss, Inc.