Ding Yunchuan, Ortelli Federica, Rossiter Louise C, Hemingway Janet, Ranson Hilary
Vector Research Group, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK.
BMC Genomics. 2003 Aug 13;4(1):35. doi: 10.1186/1471-2164-4-35.
Twenty-eight genes putatively encoding cytosolic glutathione transferases have been identified in the Anopheles gambiae genome. We manually annotated these genes and then confirmed the annotation by sequencing of A. gambiae cDNAs. Phylogenetic analysis with the 37 putative GST genes from Drosophila and representative GSTs from other taxa was undertaken to develop a nomenclature for insect GSTs. The epsilon class of insect GSTs has previously been implicated in conferring insecticide resistance in several insect species. We compared the expression level of all members of this GST class in two strains of A. gambiae to determine whether epsilon GST expression is correlated with insecticide resistance status.
Two A. gambiae GSTs are alternatively spliced resulting in a maximum number of 32 transcripts encoding cytosolic GSTs. We detected cDNAs for 31 of these in adult mosquitoes. There are at least six different classes of GSTs in insects but 20 of the A. gambiae GSTs belong to the two insect specific classes, delta and epsilon. Members of these two GST classes are clustered on chromosome arms 2L and 3R respectively. Two members of the GST supergene family are intronless. Amongst the remainder, there are 13 unique introns positions but within the epsilon and delta class, there is considerable conservation of intron positions. Five of the eight epsilon GSTs are overexpressed in a DDT resistant strain of A. gambiae.
The GST supergene family in A. gambiae is extensive and regulation of transcription of these genes is complex. Expression profiling of the epsilon class supports earlier predictions that this class is important in conferring insecticide resistance.
在冈比亚按蚊基因组中已鉴定出28个可能编码胞质谷胱甘肽S-转移酶的基因。我们对这些基因进行了人工注释，然后通过冈比亚按蚊cDNA测序对注释进行了确认。利用来自果蝇的37个假定的谷胱甘肽S-转移酶基因和来自其他分类群的代表性谷胱甘肽S-转移酶进行了系统发育分析，以建立昆虫谷胱甘肽S-转移酶的命名法。昆虫谷胱甘肽S-转移酶的ε类先前已被认为与几种昆虫物种的抗药性有关。我们比较了这一谷胱甘肽S-转移酶类所有成员在两株冈比亚按蚊中的表达水平，以确定ε谷胱甘肽S-转移酶的表达是否与抗药性状态相关。
两个冈比亚按蚊谷胱甘肽S-转移酶存在可变剪接，产生了最多32个编码胞质谷胱甘肽S-转移酶的转录本。我们在成年蚊子中检测到了其中31个的cDNA。昆虫中至少有六种不同类型的谷胱甘肽S-转移酶，但冈比亚按蚊的20个谷胱甘肽S-转移酶属于昆虫特有的两类，即δ类和ε类。这两类谷胱甘肽S-转移酶的成员分别聚集在2L和3R染色体臂上。谷胱甘肽S-转移酶超基因家族的两个成员没有内含子。在其余成员中，有13个独特的内含子位置，但在ε类和δ类中，内含子位置有相当程度的保守性。八个ε谷胱甘肽S-转移酶中的五个在冈比亚按蚊的滴滴涕抗性品系中过表达。
冈比亚按蚊的谷胱甘肽S-转移酶超基因家族广泛，这些基因的转录调控复杂。ε类的表达谱支持了早期的预测，即该类在赋予抗药性方面很重要。
