Evolution of pharyngeal behaviors and neuronal functions in free-living soil nematodes
Evolution of pharyngeal behaviors and neuronal functions in free-living soil nematodes
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DOI：
10.1242/jeb.02165
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发表时间：
2006-05-15
影响因子：
2.8
通讯作者：
Avery, L
中科院分区：
文献类型：
--
作者：
Chiang, JTA;Steciuk, M;Avery, L
为了探索秀丽隐杆线虫及其相关线虫在行为进化研究中的应用，我们对自由生活的土壤线虫的咽部行为和神经元调控进行了比较研究。咽分为咽体、峡部和终球三部分，咽行为由两种刻板的运动模式组成：抽吸和收缩。基于外类群的一个物种，Teratocephaluslirellus，祖先的咽部行为模式包括体泵，峡部扩张和终端灯泡泵，每一个独立发生。虽然身体泵仍然在很大程度上保守，峡部和终端灯泡的行为演变广泛的祖先模式在四个主要的自由生活的土壤线虫家庭。在包括秀丽隐杆线虫的小杆线虫科中，前峡部从扩张转变为泵送，前峡部和末端球泵送与小体泵送耦合。在Diploglodae科，终端球从抽水转换为膨胀，峡部和终端球成为耦合的膨胀。在Cephalobidae家庭，峡部的水和终端灯泡抽水成为耦合。而在Panagrolaidae家族中，后峡部从挤压转变为泵送。沿着这些行为变化，我们还发现了峡部和终球行为的神经元调节的差异。M2是一个在C. elegans，刺激Panagrolaimidae中的前峡。此外，M4是一个重要的兴奋性神经元，在每个家庭，但其确切的下游功能之间的刺激后峡部brachididae，峡部/终端灯泡brachidae，峡部brachidae和终端灯泡泵在头，和后峡部/终端灯泡泵Panagrolaidae。在小杆科中，虽然M4对终球没有影响，但我们发现M4对C.如果Ca ~（2+）激活的K ~+通道SLO-1失活，则对线虫的影响不大。C.在线虫的突变体中，我们发现了新的咽电图信号和增加的泵送速率，这表明M4-末端球突触的激活。因此，我们认为，缺乏M4-末端球刺激在C。线虫和小杆线虫科通过突触传递的变化进化。总之，我们发现了行为和神经元的差异，峡部和终端灯泡的自由生活的土壤线虫，我们研究了潜在的潜在机制的一个方面M4进化。我们的研究结果表明秀丽隐杆线虫和相关线虫的研究行为进化的效用。
To explore the use of Caenorhabditis elegans and related nematodes for studying behavioral evolution, we conducted a comparative study of pharyngeal behaviors and neuronal regulation in free-living soil nematodes. The pharynx is divided into three parts: corpus, isthmus and terminal bulb, and pharyngeal behaviors consist of stereotyped patterns of two motions: pumping and peristalsis. Based on an outgroup species, Teratocephalus lirellus, the ancestral pattern of pharyngeal behaviors consisted of corpus pumping, isthmus peristalsis and terminal bulb pumping, each occurring independently. Whereas corpus pumping remained largely conserved, isthmus and terminal bulb behaviors evolved extensively from the ancestral pattern in the four major free-living soil nematode families. In the Rhabditidae family, which includes Caenorhabditis elegans, the anterior isthmus switched from peristalsis to pumping, and anterior isthmus and terminal bulb pumping became coupled to corpus pumping. In the Diplogasteridae family, the terminal bulb switched from pumping to peristalsis, and isthmus and terminal bulb became coupled for peristalsis. In the Cephalobidae family, isthmus peristalsis and terminal bulb pumping became coupled. And in the Panagrolaimidae family, the posterior isthmus switched from peristalsis to pumping. Along with these behavioral changes, we also found differences in the neuronal regulation of isthmus and terminal bulb behaviors. M2, a neuron that has no detectable function in C. elegans, stimulated anterior isthmus peristalsis in the Panagrolaimidae. Further, M4 was an important excitatory neuron in each family, but its exact downstream function varied between stimulation of posterior isthmus peristalsis in the Rhabditidae, isthmus/terminal bulb peristalsis in the Diplogasteridae, isthmus peristalsis and terminal bulb pumping in the Cephalobidae, and posterior isthmus/terminal bulb pumping in the Panagrolaimidae. In the Rhabditidae family, although M4 normally has no effect on the terminal bulb, we found that M4 can stimulate the terminal bulb in C. elegans if the Ca2+ activated K+ channel SLO-1 is inactivated. C. elegans slo-1 mutants have generally increased neurotransmission, and in slo-1 mutants we found novel electropharyngeogram signals and increased pumping rates that suggested activation of M4-terminal bulb synapses. Thus, we suggest that the lack of M4-terminal bulb stimulations in C. elegans and the Rhabditidae family evolved by changes in synaptic transmission. Altogether, we found behavioral and neuronal differences in the isthmus and terminal bulb of free-living soil nematodes, and we examined potential underlying mechanisms of one aspect of M4 evolution. Our results suggest the utility of Caenorhabditis elegans and related nematodes for studying behavioral evolution.