Evaluation of Sublethal Effects of Dichlorvos upon Caenorhabditis elegans Based on a Set of End Points of Toxicity

The primary objective of this study was
to examine a possible correlation among the three
endpoints of toxicity, namely, stress gene expression
(hsp16), feeding, and acetylcholinesterase (AChE) activity
in transgenic C. elegans (hsp16-lacZ) exposed to
sublethal concentrations of dichlorvos, an organophosphorus
insecticide.Worms exposed to dichlorvos (at 5,
40, and 80 μM) exhibited a concentration-dependent
inhibition in feeding with total cessation in feeding
occurring beyond 4 h of exposure. Concomitantly,
marked and dose-dependent inhibition (69%–90%) of
AChE was also evident after 4 h of exposure. Induction
of heat shock protein (Hsp) was evident after
4 h of exposure (as seen from quantitative analysis),
although maximum expression of Hsp was evident
only after 24 h of exposure (as evident from qualitative
analysis). Interestingly, the Hsp induction was restricted
only to the pharyngeal region. Significant correlation
was discernible between the three evaluated
end points suggesting their possible interrelated role
in the physiological dysfunctions evoked by sublethal
concentrations of dichlorvos.