The New World screwworm (NWS) Cochliomyia hominivorax (Coquerel) is one of the major myiasis-causing flies that injures livestock and leads to losses of ~US$ 2.7 billions/year in the Neotropics. Ivermectin (IVM), a macrocyclic lactone (ML), is the most used preventive insecticide for this parasite and targets the glutamate-gated chloride (GLUCLα) channels. Several authors have associated altered GluClα homologues to MLs resistance in invertebrates, although studies about resistance in NWS are limited to other genes. Here, we aimed to characterise the NWS GluClα (ChGluClα) cDNA and to search for alterations associated with IVM resistance in NWS larvae from a bioassay. The open reading frame of the ChGluClα comprised 1,359 bp and encoded a sequence of 452 amino acids. The ChGluClα cDNAs of the bioassay larvae showed different sequences that could be splice variants, which agree with the occurrence of alternative splicing in GluClα homologues. In addition, we found cDNAs with premature stop codons and the K242R SNP, which occurred more frequently in the surviving larvae and was located close to mutation (L256F) involved in ML resistance. Although these alterations were in low frequency, the ChGluClα sequencing will allow further studies to find alterations in the gene of resistant natural populations.

中文翻译：

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Cochliomyia hominivorax（双翅目：Calliphoridae）的谷氨酸门控氯通道亚基 cDNA 测序：cDNA 变体和多态性。

新世界螺旋蠕虫 (NWS) Cochliomyia hominivorax (Coquerel) 是导致家畜受伤的主要蝇蛆病之一，在新热带地区每年造成约 27 亿美元的损失。伊维菌素 (IVM) 是一种大环内酯 (ML)，是该寄生虫最常用的预防性杀虫剂，针对谷氨酸门控氯 (GLUCLα) 通道。几位作者将改变的GluClα同系物与无脊椎动物的 MLs 抗性联系起来，尽管关于 NWS 抗性的研究仅限于其他基因。在这里，我们旨在表征 NWS GluClα (Ch GluClα ) cDNA 并通过生物测定寻找与 NWS 幼虫 IVM 抗性相关的改变。Ch GluClα的开放阅读框包含 1,359 bp 并编码 452 个氨基酸的序列。生物测定幼虫的 Ch GluClα cDNA 显示出可能是剪接变体的不同序列，这与GluClα同源物中发生选择性剪接的情况一致。此外，我们发现了具有过早终止密码子和 K242R SNP 的 cDNA，它们在幸存的幼虫中更频繁地出现，并且位于与 ML 抗性相关的突变 (L256F) 附近。尽管这些改变频率较低，但 Ch GluClα测序将允许进一​​步研究以发现抗性自然种群基因的改变。