Induction of glutathione S‐transferases activities in Drosophila melanogaster exposed to phenol

Abstract

Studying the toxic effects of long-term exposing fruit flies to phenol is the object of this study. The induction of the glutathione S-transferases enzymatic activities, the change in the amount of mRNA related to phenol exposure, the change in survival rate of adult fruit flies, and the chemical interaction between phenol and benzene were the problems to be investigated. Glutathione S-transferases were separated by affinity chromatography and the mRNAs levels were quantified by reverse-transcription polymerase chain reaction. Long-term feeding phenol to wild type fruit flies had caused some toxic effects included increasing the resistance to phenol toxicity, lowering the benzene toxicity, and induction of glutathione S-transferases enzymatic activities. But no significant change in the amount of glutathione S-transferases GstD1 and GstD5 mRNAs had occurred. From these results, we concluded that fruit flies could develop resistance to phenol by decreasing its toxicity; phenol was a inducer of glutathione S-transferases; phenol could increase the glutathione S-transferases enzymatic activities by increasing the amount of proteins; phenol exposure could decrease the benzene toxicity; no new glutathione S-transferase isozyme subunit was induced; and the level of GstD1 and GstD5 mRNAs did not significantly increase in phenol-treated strain.

Effects of imidacloprid on detoxifying enzyme glutathione S-transferase on Folsomia candida (Collembola)

“…The activity of GSTs was determined according to Shen and Chien (2003). Briefly, assays were performed by recording the first 2 min of GS-CDNB conjugation at 25°C in the reaction mixture consisting of 100 μL of 50 mM GSH (Sigma-Aldrich, Taufkirchen, Germany), 40 μL of 50 mM 1-chloro-2,4-dinitrobenzene (CDNB) (Sigma-Aldrich, Taufkirchen, Germany) dissolved in ethanol, 10 μL of enzyme extract, and 0.1 M potassium phosphate buffer, pH 6.5, in a total volume of 2 mL.…”

“…Various isoforms of GST, with different substrate specificities covering a broad spectrum of xenobiotics, are found in organisms, giving GSTs a central role in the detoxification of organic substances. GSTs have been studied in many species such as mussels (Fitzpatrick and Sheehan 1993;Fitzpatrick et al 1995), insects (Kostaropoulos and Papadopoulos 1998;Kostaropoulos et al 2001;Shen and Chien 2003), earthworms (Aly and Schroeder 2008;Ribera et al 2001), and especially mammals (Johnson et al 1993;Antunes et al 2009). A recent classification system separates insect GSTs into six classes including Delta, Epsilon, Omega, Theta, Sigma, and Zeta (Agianian et al 2003;Enayati et al 2005).…”

Interactions between detoxification mechanisms and excretion in Malpighian tubules ofDrosophila melanogaster

“…GST activities increase in Drosophila reared for more than seven generations on diet containing 0.3% phenol (Shen et al, 2003). We therefore assessed whether increases in GST activity were correlated with an increase in secretion of the MRP substrate methotrexate.…”

“…Willoughby et al, 2007), whereas dietary PBO is associated with decreases in expression of GstD1 and GstD5 in the tubules and a 1.5-fold increase in GstE1. It is important to exercise caution in inferring changes in enzymatic actvity of GSTs in the tubules because whole-fly studies indicate that phenol exposure may result in increases in GST enzymatic activity but no change in the levels of mRNA for GstD1, GstD5, GstD8 and GstE1 and a reduction in the levels of mRNA for GstD4 and GstD7 (Shen et al, 2003;Ding et al, 2005). Our functional studies also showed that MTX secretion more than doubled in tubules of flies reared on the phenol-enriched diet for seven to 10 generations relative to controls.…”

“…The Cyp genes Cyp6a2, Cyp6a8 and Cyp12d1, which are most strongly induced by PBO in adult male Drosophila, are also among the 12 Cyp genes associated with insecticide resistance (Willoughby et al, 2007;Giraudo et al, 2010). Previous studies have also shown that rearing Drosophila for multiple generations on diets containing 0.3% phenol is associated with an increase in GST enzymatic activity but with no change in the levels of mRNA for GstD1, GstD5, GstD8 and GstE1 and with a reduction in the levels for GstD4 and GstD7 (Shen et al, 2003;Ding et al, 2005).…”