title: ABC transporters are involved in defense against permethrin insecticide in the malaria vector Anopheles stephensi.
abstract: BACKGROUND
  Proteins from the ABC family (ATP-binding cassette) represent the largest known group of efflux pumps, responsible for transporting specific molecules across lipid membranes in both prokaryotic and eukaryotic organisms. In arthropods they have been shown to play a role in insecticide defense/resistance. The presence of ABC transporters and their possible association with insecticide transport have not yet been investigated in the mosquito Anopheles stephensi, the major vector of human malaria in the Middle East and South Asian regions. Here we investigated the presence and role of ABCs in transport of permethrin insecticide in a susceptible strain of this mosquito species.
  
  
  METHODS
  To identify ABC transporter genes we obtained a transcriptome from untreated larvae of An. stephensi and then compared it with the annotated transcriptome of Anopheles gambiae. To analyse the association between ABC transporters and permethrin we conducted bioassays with permethrin alone and in combination with an ABC inhibitor, and then we investigated expression profiles of the identified genes in larvae exposed to permethrin.
  
  
  RESULTS
  Bioassays showed an increased mortality of mosquitoes when permethrin was used in combination with the ABC-transporter inhibitor. Genes for ABC transporters were detected in the transcriptome, and five were selected (AnstABCB2, AnstABCB3, AnstABCB4, AnstABCmember6 and AnstABCG4). An increased expression in one of them (AnstABCG4) was observed in larvae exposed to the LD50 dose of permethrin. Contrary to what was found in other insect species, no up-regulation was observed in the AnstABCB genes.
  
  
  CONCLUSIONS
  Our results show for the first time the involvement of ABC transporters in larval defense against permethrin in An. stephensi and, more in general, confirm the role of ABC transporters in insecticide defense. The differences observed with previous studies highlight the need of further research as, despite the growing number of studies on ABC transporters in insects, the heterogeneity of the results available at present does not allow us to infer general trends in ABC transporter-insecticide interactions.
authors: Sara
authors: S
authors: Epis
authors: Daniele
authors: D
authors: Porretta
authors: Valentina
authors: V
authors: Mastrantonio
authors: Francesco
authors: F
authors: Comandatore
authors: Davide
authors: D
authors: Sassera
authors: Paolo
authors: P
authors: Rossi
authors: Claudia
authors: C
authors: Cafarchia
authors: Domenico
authors: D
authors: Otranto
authors: Guido
authors: G
authors: Favia
authors: Claudio
authors: C
authors: Genchi
authors: Department of Veterinary Science and Public Health, University of Milan, Milan, Italy. claudio.bandi@unimi.it.
authors: Claudio
authors: C
authors: Bandi
authors: Sandra
authors: S
authors: Urbanelli
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D000852:Anopheles / Q000187:drug effects; D001681:Biological Assay; D005786:Gene Expression Regulation / Q000502:physiology; D007305:Insecticide Resistance; D007306:Insecticides / Q000494:pharmacology*; D007814:Larva; D026023:Permethrin / Q000494:pharmacology*; D059467:Transcriptome
chemical_list: D018528:ATP-Binding Cassette Transporters; D007306:Insecticides; D026023:Permethrin