Kwa M S, Veenstra J G, Roos M H
Department of Parasitology, Faculty of Veterinary Medicine, University of Utrecht, The Netherlands.
Mol Biochem Parasitol. 1993 Jul;60(1):133-43. doi: 10.1016/0166-6851(93)90036-w.
A beta-tubulin isotype 1 gene, gru-1, from a benzimidazole (BZ)-resistant population of the nematode parasite, Haemonchus contortus, was cloned and sequenced. The predicted gene organisation showed 10 exons and 9 introns, one of which was H. contortus specific. Using probes and restriction sites selected from this sequence, restriction maps were constructed from and around beta-tubulin genes of 3 BZ-susceptible and 7 BZ-resistant populations. There was a reduction in beta-tubulin isotype 1 genes to usually one, in BZ-resistant populations. So, our previously reported reduction of beta-tubulin probe-reactive RFLP fragments in resistant populations correlated with the reduction of beta-tubulin isotype 1 genes. The beta-tubulin isotype 1 gene present on the apparently selected fragment and was not always the same, and the geographical origin of the resistant populations indicated independent development rather than geographical spread of the resistant populations. The beta-tubulin genes on the apparently selected fragments were transcribed and processed to mRNA using the nematode-specific trans-spliced leader (SL1). Comparison of the derived amino acid sequence of gru-1, with known sequences from a susceptible population, identified 3 mutations that could be involved in BZ resistance.
从抗苯并咪唑（BZ）的捻转血矛线虫寄生群体中克隆并测序了一个β-微管蛋白1亚型基因gru-1。预测的基因结构显示有10个外显子和9个内含子，其中一个是捻转血矛线虫特有的。利用从该序列中选择的探针和限制性酶切位点，构建了3个BZ敏感群体和7个BZ抗性群体的β-微管蛋白基因及其周围区域的限制性图谱。在BZ抗性群体中，β-微管蛋白1亚型基因通常减少到一个。因此，我们之前报道的抗性群体中β-微管蛋白探针反应性RFLP片段的减少与β-微管蛋白1亚型基因的减少相关。明显选择片段上存在的β-微管蛋白1亚型基因并不总是相同的，抗性群体的地理起源表明抗性群体是独立发展而非地理传播。明显选择片段上的β-微管蛋白基因利用线虫特异性反式剪接前导序列（SL1）转录并加工成mRNA。将gru-1推导的氨基酸序列与敏感群体的已知序列进行比较，鉴定出3个可能与BZ抗性有关的突变。
