Effect of Three Chlorinated Pesticides on hsrω Stress gene in Transgenic Drosophila melanogaster

✍ Scribed by D. Kar Chowdhuri; Aamir Nazir; D. K. Saxena

• Publisher: John Wiley and Sons
• Year: 2001
• Tongue: English
• Weight: 881 KB
• Volume: 15
• Category: Article
• ISSN: 1095-6670
• DOI: 10.1002/jbt.15

✦ Synopsis

Abstract

Expression of hsrω stress gene in the third‐instar larvae of 951‐lacZ2
(hsrω‐lacZ having–844pb sequence) and 498‐lacZ1
(hrsω‐lacZ having –498bp sequence) strains of Drosophila melanogaster
at LC~50~ and lower dietary concentrations of hexachlorocyclohexane (HCH) pentachlorophenol
(PCP), and endosulfan was examined in relation to larval mortality by β galactosidase activity,
vital dye staining, and salivary gland polytene chromosome puffing. Our results showed that both HCH and PCP at
lower concentrations evoked strong hsrω stress gene expression in the larval tissues while
endosulfan did not. On the other hand, puffing data revealed that endosulfan at lower doses, induced
well‐developed puff at the resident site (93D) of the hsrω gene but the transgenic
sites (30B in 951‐lacZ2 and 44B in 498‐lacZ1 strain) did not show any
well‐developed puff. Regression in hsrω stress gene expression in 951‐lacZ2 strain at
LC~50~ concentrations of HCH and PCP after 48 h was concurrent with extensive tissue damage as evident
by trypan blue staining. Similarly, strong hsrω expression was accompanied by insignificant trypan
blue staining in the larval tissues of this strain after shorter duration of exposure (2–12 h)
to these toxicants. Although endosulfan under similar experimental condition did not induce hsrω,
strong trypan blue staining indicated extensive tissue damage after 48 h of exposure. The present study suggests
that all the three toxicants pose cytotoxic potential to Drosophila. While protective role of this stress
gene was evident at the initial stages of exposure, extensive tissue damage in the later stages of intoxication
accompanied by autorepression of hsrω led to larval mortality. The study further suggests that
–844bp upstream sequence of the gene is adequate for hsrω inducibility against HCH and PCP
but not for endosulfan for which responsive elements may be searched further upstream. © 2001 John Wiley
& Sons, Inc. J Biochem Mol Toxicol 15:173–186, 2001