PNAS：科学家发现对杀虫剂产生抗性的疟疾超级杂交蚊子

  近日，一篇刊登在国际杂志Proceedings of the National Academy of Sciences上的论文中，来自加利福尼亚大学的研究人员在西非国家马里发现了两种疟疾蚊子物种的杂交种，这或许会产生一种对经杀虫剂处理过的蚊帐具有抗性的“超级蚊子”。

  文章中，研究者表示，环境的人为改变，即杀虫剂的引入会改变两个物种（引发疟疾的蚊子物种）的进化关系，从而就会打破它们之间的生殖隔离；本文中研究人员就发现，对杀虫剂耐药性的快速进化或许主要发生在引发疟疾的蚊子物种中，而冈比亚按蚊，主要的疟疾载体，其可以同另外一种疟疾载体—coluzzii按蚊（A. coluzzii）发生杂交，研究人员起初认为coluzzii按蚊是冈比亚按蚊的M-S形式，但后来却发现这两种蚊子是独立分开的两个物种。
杀虫剂耐药性的出现并不奇怪，近年来其在非洲的某些地区已经达到了一定的水平，从而常常使得防御疟疾的防蚊帐失去作用；据世界卫生组织数据显示，随着2000年以来马里地区感染疟疾死亡的患者数量下降了47%，这其中大部分功劳都归因于杀虫剂防蚊帐的投放。

  然而好景不长，随着防蚊帐的使用慢慢产生了杀虫剂耐药性，如今研究人员急需开发一种新型有效的控制疟疾的载体，当然目前有许多新型策略被开发，包括新型的杀虫剂，生物制剂等，或者是开发新型的遗传工程化操作的蚊子来杀灭那些可以传播疟原虫的蚊子。

  最后研究者Lanzaro说道，本文研究中我们发现了两种疟疾蚊子的新型杂交种，其对于后期开发新型疗法来有效抑制蚊子传播疟疾提供了一定的线索和帮助。（转化医学网360zhyx.com）
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转化医学网推荐的原文摘要：

Adaptive introgression in an African malaria mosquito coincident with the increased usage of insecticide-treated bed nets
PNAS doi: 10.1073/pnas.1418892112
Laura C. Norrisa,b, Bradley J. Maina,c, Yoosook Leea,c, Travis C. Colliera,c, Abdrahamane Fofanad, Anthony J. Cornela,b, and Gregory C. Lanzaroa,c,1
Animal species adapt to changes in their environment, including man-made changes such as the introduction of insecticides, through selection for advantageous genes already present in populations or newly arisen through mutation. A possible alternative mechanism is the acquisition of adaptive genes from related species via a process known as adaptive introgression. Differing levels of insecticide resistance between two African malaria vectors, Anopheles coluzzii and Anopheles gambiae, have been attributed to assortative mating between the two species. In a previous study, we reported two bouts of hybridization observed in the town of Selinkenyi, Mali in 2002 and 2006. These hybridization events did not appear to be directly associated with insecticide-resistance genes. We demonstrate that during a brief breakdown in assortative mating in 2006, A. coluzzii inherited the entire A. gambiae-associated 2L divergence island, which includes a suite of insecticide-resistance alleles. In this case, introgression was coincident with the start of a major insecticide-treated bed net distribution campaign in Mali. This suggests that insecticide exposure altered the fitness landscape, favoring the survival of A. coluzzii/A. gambiae hybrids, and provided selection pressure that swept the 2L divergence island through A. coluzzii populations in Mali. We propose that the work described herein presents a unique description of the temporal dynamics of adaptive introgression in an animal species and represents a mechanism for the rapid evolution of insecticide resistance in this important vector of human malaria in Africa.