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Structural organization of the est alpha 3(1) gene in a Colombian strain of Culex quinquefasciatus differs from that in Cuba

De Silva, D. and Hemingway, Janet ORCID: (2002) 'Structural organization of the est alpha 3(1) gene in a Colombian strain of Culex quinquefasciatus differs from that in Cuba'. Medical and Veterinary Entomology, Vol 16, Issue 1, pp. 99-105.

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In Culex mosquitoes (Diptera: Culicidae), the most common mechanism for resistance to organophosphorus (OP) insecticides involves amplification of one or more esterases. Two esterase loci are often involved, with different allelic forms co-amplified. Estalpha3(1) is co-amplified with estbeta1 in a Colombian (COL) strain of Culex quinquefasciatus Say. These two alleles co-migrate on acrylamide gels, often leading to misscoring of the phenotype as elevation of a single estbeta enzyme. By sequencing COL genomic DNA, we determined the estalpha3(1) gene length is 1623 nucleotides. The open reading frame of estalpha3(1) encodes a 540 amino acid protein, as for estalpha2(1) in strain Pel RR from Sri Lanka. The intron/exon boundaries of estalpha3(1) are identical to those of estalpha2(1), suggesting that they are alleles of the same locus. The COL estalpha3(1) gene differs from estalpha3(2) in strain MRES from Cuba, although they have equivalent electrophoretic mobility, showing that these two strains contain distinct resistance-associated amplicons. Twenty nucleotide differences were scored between the MRES partial 495 bp sequence and that in the COL strain, with two amino acid changes, demonstrating distinct estalpha enzymes. Our sequencing data show 95% identity between the three estalpha genes (each has six introns and seven exons) in OP-resistant Cx. quinquefasciatus. Amplified estalpha3(1) and estbeta1 are at least 10 kb apart in temephos-selected COL and 2.7 kb apart in Pel RR, whereas these non-amplified genes are only 1.7 kb apart in the non-selected parental COL stock, as in Pel SS (susceptible Sri Lankan strain), demonstrating that this region of the genome is susceptible to expansion and contraction.

Item Type: Article
Additional Information: The definitive version is available at
Subjects: QX Parasitology > QX 20 Research (General)
QX Parasitology > Insects. Other Parasites > QX 510 Mosquitoes
QX Parasitology > Insects. Other Parasites > QX 530 Culex
WA Public Health > Health Problems of Special Population Groups > WA 395 Health in developing countries
Faculty: Department: Groups (2002 - 2012) > Vector Group
Digital Object Identifer (DOI):
Depositing User: Users 476 not found.
Date Deposited: 03 Dec 2012 15:19
Last Modified: 09 Aug 2017 01:03


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