Induction of Detoxification Enzymes by Quercetin in the Silkworm

Abstract

Quercetin is one of the most abundant flavonoids and the defense secondary metabolites in plants. In this study, the effect of quercetin on the growth of the silkworm larvae was investigated. Cytochrome P450 monooxygenases (P450s), glutathione S-transferases (GSTs), and carboxylesterases (COE) were assayed after exposure to different concentrations of quercetin for 3 d (short-term) and 7 d (long-term), respectively. The results showed that the weight gain of the silkworm larvae significantly decreased after the larvae were treated by different concentrations of quercetin except for the treatment with 0.5% quercetin. Activities of P450, GST, and COE were induced by 0.5 or 1% concentration of quercetin. In the midgut, the induction activity of P450s was reached to the highest level (2.3-fold) by 1% quercetin for 7 d, the highest induction activities of GSTs toward CHP and CDNB were 4.1-fold and 2.6-fold of controls by 1% quercetin after 7 d exposure, respectively. For COEs, the highest activity (2.3-fold) was induced by 0.5% quercetin for 7 d. However, P450s in whole body were higher inducible activities in short-term treatment than those in long-term treatment. The responses of eight cytochrome P450 (CYP) genes belonged to CYP6 and CYP9 families and seven GST genes were detected with real-time polymerase chain reaction. In addition, the genes induced by quercetin significantly were confirmed by qRT-PCR. CYP6AB5, CYP6B29, and GSTe8 were identified as inducible genes, of which the highest induction levels were 10.9-fold (0.5% quercetin for 7 d), 6.2-fold (1% quercetin for 7 d), and 7.1-fold (1% quercetin for 7 d), respectively.

Glutathione-S-transferase profiles in the emerald ash borer, Agrilus planipennis

“…Epsilon group members, particularly ApGST-E1 and ApGST-E3 showed peak mRNA levels in the midgut tissue wherein they might be participating in metabolizing dietary toxins ingested from the host plant. Several studies of plant-insect interaction have shown the midgut tissue as the major interface for several detoxification enzymes including GSTs (Hakim et al, 2010;Mittapalli et al, 2010;Pauchet et al, 2010;Rajarapu et al, 2011;Zhang et al, 2012). ApGST-E2 was also high in Malpighian tubules, an important physiological (renal) tissue that is vital in eliminating dietary toxins as reported in other insects (Chahine and O'Donnell, 2011).…”

MOLECULAR CHARACTERIZATION OF TWO CARBOXYLESTERASE GENES OF THE CITRUS RED MITE, Panonychus citri (ACARI: TETRANYCHIDAE)

“…In many cases, gene amplification following an exposure to xenobiotic compounds enhances expression levels of metabolic enzymes that in turn triggers resistance. Examples of induction of CarEs by xenobiotics are reported by Yu, and Zhang et al, .…”

“…In many cases, gene amplification following an exposure to xenobiotic compounds enhances expression levels of metabolic enzymes that in turn triggers resistance. Examples of induction of CarEs by xenobiotics are reported by Yu, 2004 andZhang et al, 2012. Beside the detoxification, CarEs are involved in other insects physiological processes including regulation of the growth and development. It has been shown that the r 215 expression patterns of CarE genes vary during different developmental stages and different sexes suggesting possible functional roles of the CarE genes (Campbell et al, 2003;Mujeeb and Shakoori, 2012).…”

Stage-specific quercetin sulfation in the gut of Mythimna separata larvae (Lepidoptera: Noctuidae)

“…3) In this study, oriental armyworm Mythimna separata larvae were fed artificial diets containing 1% quercetin to investigate how M. separata larvae would cope with the toxic compound. The metabolism of quercetin in insects is still unclear and requires further investigation, although quercetin 5-O-glucoside has been identified from orally administrated quercetin in the Bombyx mori silkworm.…”