RESUMO
Resistance to permethrin in an East African population of the major malaria vector, Anopheles gambiae is multifactorial. A mutated sodium channel allele and enhanced insecticide metabolism contribute to the resistance phenotype. We used microsatellite markers to scan the genome for quantitative trait loci (QTL) associated with permethrin resistance. Two major and one minor QTL were identified. The first QTL, rtp1, colocalizes with the sodium channel gene on chromosome 2L thus further supporting the importance of mutations in this gene in conferring permethrin resistance. The second two loci are located on the third chromosome and one of these, rtp2, flanks a large cluster of cytochrome P450 genes. Further detailed mapping of these regions will help elucidate the molecular mechanisms of metabolic resistance to insecticides.
Assuntos
Anopheles/genética , Mapeamento Cromossômico , Permetrina/toxicidade , Animais , Anopheles/efeitos dos fármacos , Cruzamentos Genéticos , Primers do DNA , Resistência a Inseticidas/genética , Repetições de Microssatélites/genética , Mutação/genética , Locos de Características Quantitativas/genética , Canais de Sódio/genéticaRESUMO
piggyBac is a short inverted-repeat-type DNA transposable element originally isolated from the genome of the moth Trichoplusia ni. It is currently the gene vector of choice for the transformation of various insect species. A few sequences with similarity to piggyBac have previously been identified from organisms such as humans ( Looper), the pufferfish Takifugu rubripes ( Pigibaku), Xenopus ( Tx), Daphnia ( Pokey), and the Oriental fruit fly Bactrocera dorsalis. We have now identified 50 piggyBac-like sequences from publicly available genome sequences and expressed sequence tags (ESTs). This survey allows the first comparative examination of the distinctive piggyBac transposase, suggesting that it might contain a highly divergent DDD domain, comparable to the widespread DDE domain found in many DNA transposases and retroviral integrases which consists of two absolutely conserved aspartic acids separated by about 70 amino acids with a highly conserved glutamic acid about 35 amino acids further away. Many piggyBac-like sequences were found in the genomes of a phylogenetically diverse range of organisms including fungi, plants, insects, crustaceans, urochordates, amphibians, fishes and mammals. Also, several instances of "domestication" of the piggyBac transposase sequence by the host genome for cellular functions were identified. Novel members of the piggyBac family may be useful in genetic engineering of many organisms.
Assuntos
Elementos de DNA Transponíveis/genética , Evolução Molecular , Animais , Anopheles/genética , Genes de Insetos , Genoma Humano , Humanos , Mariposas/genética , Filogenia , Tetraodontiformes/genéticaRESUMO
A Bacterial Artificial Chromosome (BAC) genomic DNA library of Anopheles gambiae, the major human malaria vector in sub-Saharan Africa, was constructed and characterized. This library (ND-TAM) is composed of 30,720 BAC clones in eighty 384-well plates. The estimated average insert size of the library is 133 kb, with an overall genome coverage of approximately 14-fold. The ends of approximately two-thirds of the clones in the library were sequenced, yielding 32,340 pair-mate ends. A statistical analysis (G-test) of the results of PCR screening of the library indicated a random distribution of BACs in the genome, although one gap encompassing the white locus on the X-chromosome was identified. Furthermore, combined with another previously constructed BAC library (ND-1), ~2,000 BACs have been physically mapped by polytene chromosomal in situ hybridization. These BAC end pair mates and physically mapped BACs have been useful for both the assembly of a fully sequenced A. gambiae genome and for linking the assembled sequence to the three polytene chromosomes. This ND-TAM library is now publicly available at both http://www.malaria.mr4.org/mr4pages/index.html/ and http://hbz.tamu.edu/, providing a valuable resource to the mosquito research community.
