Activation of a stress‐induced gene by insecticides in the midge, Chironomus yoshimatsui

Abstract

Stress proteins (heat shock proteins, HSPs) have been proposed as general biomarkers for environmental monitoring. In the present study, we evaluated the environmental stress-burden on the aquatic midge Chironomus yoshimatsui using hsp70 expression. Larvae collected from streams receiving polluted runoff (field strain) were resistant to the organophosphorus insecticide, fenitrothion (F), and the synthetic pyrethroid, ethofenprox (E), whereas a strain originally collected from an unpolluted area (susceptible strain) showed low resistance to insecticide exposure. To examine the expression of an HSP70 gene in C. yoshimatsui, an hsp70 cDNA probe was prepared using RNA obtained from the field strain larvae and used for Northern blot analyses. The expression of this HSP70 gene in larvae collected from two field sites in May about 1 week after insecticide spraying in the fields was 2.3 (p = 0.018) to 3.3 fold higher than that in the susceptible strain and was also 4.6 and 1.4 (p = 0.033) fold higher than those collected in November 3 months after the cessation of insecticide spraying. In order to identify potential inducers of the HSP70 gene of the field strain, larvae of the susceptible strain were exposed to F or E for 24 h and hsp70 mRNA levels determined. Exposures to F at 0.4 microg/L and E at 1.1 microg/L increased hsp70 mRNA levels 2.7 (p = 0.049) and 4.4 (p = 0.043) fold over controls, respectively. These results suggest that larvae collected from polluted areas are burdened by environmental stressors and the tested insecticides are potential inducers of HSP70. The results also support the suggestion that HSP70 gene expression is a sensitive indicator of low level (nonlethal) exposures to certain insecticides.

Identification of heat shock protein genes hsp70s and hsc70 and their associated mRNA expression under heat stress in insecticide-resistant and susceptible diamondback moth, Plutella xylostella (Lepidoptera: Plutellidae)

“…For example, up-regulated expression of hsp70 under heat stress was found in many insects, such as noctuid pest moth species Helicoverpa zea (Boddie) (Zhang & Denlinger, 2010), Spodoptera exigua (Hübner) (Xu et al, 2011) and S. litura (Fabricius) (Shen et al, 2014), hymenopterous wasp parasitoids, Macrocentrus cingulum (Xu et al, 2010) and Cotesia vestalis Haliday (Braconidae) (Shi et al, 2013) and the fruit fly, D. melanogaster (Udaka et al, 2010). Increased expression of hsp70 was observed when the non-biting midge, Chironomus yoshimatsui Martin & Sublette (Diptera: Chironomidae), or D. melanogaster was treated with pyrethroid insecticide (Mukhopadhyay et al, 2002;Yoshimi et al, 2002). The insect hsp70 expression was strongly up-regulated in response to heavy metals, including Zn, Cu, Cd, Ag, Pb and Ni (Sonoda et al, 2007;Augustyniak et al, 2009;Karouna-Renier & Rao, 2009;Ahamed et al, 2010).…”

Characterization of the small heat shock protein Hsp27 gene in Chironomus riparius (Diptera) and its expression profile in response to temperature changes and xenobiotic exposures

“…In recent years, some genes have been described as biomarkers for toxicant exposures including, among others, those for heat shock proteins (Hsp70, Hsc70, Hsp90, Hsp40), ribosomal proteins, cytochrome P450, and nuclear receptors Gopalakrishnan et al, 2011;Morales et al 2011;Planelló et al 2007;2008;Park and Kwak 2008Martínez-Paz et al 2012;Ozáez et al 2013). Hsp70 has been sequenced and evaluated as a biomarker of exposure to metals and insecticides in other species of chironomids, such as Chironomus yoshimatsui and Chironomus dilutus (Yoshimi et al 2002;Karouna-Renier and Rao 2009). However, there is still scarce DNA sequence information for these aquatic species and, in particular, the family of small Hsps genes has not yet been characterized.…”

Gene expression of hsp70 of the diamondback moth, Plutella xylostella (Lepidoptera: Yponomeutidae), in response to heat shock and insecticides

“…It has been shown that the expression of hsp70 is induced in response to 0.4 mg/l fenitrothion (organophosphate) and 0.4 mg/l ethofenprox (pyrethroid) in the midge, C. yoshimatsui (Yoshimi et al, 2002). Mukhopadhyay et al (2002) showed the induction of hsp70 expression in response to cypermethrin (pyrethroid) at 0.002 ppm using transgenic D. melanogaster.…”

“…In one such study, Yoshimi et al (2002) reported that the expression of hsp70 in the midge, Chironomus yoshimatsui, is induced in response to organophosphate (fenitrothion) and pyrethroid (ethofenprox). They suggested that hsp70 is a sensitive indicator of low-level exposure to certain insecticides.…”