Developmental switching in the parasitic nematode Strongyloides stercoralis is controlled by the ASF and ASI amphidial neurons
Developmental switching in the parasitic nematode Strongyloides stercoralis is controlled by the ASF and ASI amphidial neurons
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DOI：
10.2307/3284571
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发表时间：
1998-08-01
影响因子：
1.3
通讯作者：
Schad, GA
中科院分区：
文献类型：
--
作者：
Ashton, FT;Bhopale, VM;Schad, GA
类圆线虫属的寄生线虫因其能够响应内部环境条件的变化而在不同的自由生活发育途径之间切换而引人注目。离开宿主后，土壤幼虫阶段可以通过2个微生物阶段（同源发育）发展到感染性，或者通过4个微生物幼虫阶段（异源发育）发展到自由生活的成年期。这些成虫的后代随后进入感染期。在后一种情况下，自由生活的存在时间延长，感染性幼虫的数量大大增加。前化学感受神经元（端足神经元）被认为对环境信号做出反应，并通过信号转导途径控制幼虫的发育方向。我们现在证明，通过激光微束消融，2类amphidial神经元（ASF和ASI），共同作用，控制自由生活的幼虫发展的方向。其中神经元被杀死的幼虫通过同源途径发展成感染性，而不是通过其他主要的异源途径发展成成虫。这些神经元可能同源的神经元ADF（=ASF）和ASI秀丽隐杆线虫，这表明在细胞水平上的发展控制是保守的不同类群的线虫。这些观察结果也有重要的影响，线虫寄生的进化和设计新的预防措施，对医学和兽医医学的重要性寄生线虫。
Parasitic nematodes of the genus Strongyloides are remarkable for their ability to switch between alternative free-living developmental pathways in response to changing internal environmental conditions. After exiting the host, soil-dwelling larval stages may develop either to infectivity via 2 microbiverous stages (homogonic development) or to free-living adulthood via 4 microbiverous larval stages (heterogonic development). The progeny of these adults then give rise to the infective stage. In the latter case, free-living existence is extended in time and the number of infective larvae is greatly amplified. Anterior chemosensory neurons (amphidial neurons) are thought to respond to environmental cues and via signal transduction pathways control the direction of larval development. We now demonstrate by laser microbeam ablation that 2 classes of amphidial neurons (ASF and ASI), acting together, control the direction of free-living larval development. Larvae in which the neurons were killed developed to infectivity via the homogonic route rather than to adulthood via the otherwise predominant heterogenic route. These neurons are probable homologues of neurons ADF (=ASF) and ASI in Caenorhabditis elegans, suggesting the control of development at the cellular level is conserved among divergent taxa of nematodes. These observations also have important implications for the evolution of nematode parasitism and the design of new prophylactic measures against parasitic nematodes of medical and veterinary medical importance.