《Nature Neuroscience》3月4日在線發(fā)表英國劍橋大學(xué)的研究人員的研究報(bào)告，該報(bào)告報(bào)道了秀麗隱桿線蟲應(yīng)對環(huán)境中氧濃度變化的行為調(diào)節(jié)機(jī)制,。這項(xiàng)研究幫助我們在了解動(dòng)物的持續(xù)防御行為方面邁出重要的一步,。
對所有生物而言，每時(shí)每刻都有一大堆的環(huán)境信息需要應(yīng)對,，因此其感知系統(tǒng)會進(jìn)化產(chǎn)生相應(yīng)的適應(yīng)機(jī)制以對大多數(shù)環(huán)境刺激作出快速反應(yīng)或忽略某些刺激,。一些有害刺激能在很長時(shí)間內(nèi)被生物所記住，但是,，人們目前還不完全了解控制這種持續(xù)反應(yīng)的調(diào)節(jié)機(jī)制,。
在野外條件下，秀麗隱桿線蟲有可能處于氧濃度變化差異很大的環(huán)境中,。而在這樣的環(huán)境下,，這種線蟲可以通過改變移動(dòng)速度、方向,，或者聚集起來共同降低氧濃度的方式應(yīng)對高低不同的氧濃度,。Mario De Bono和同事研究了線蟲的氧氣感知神經(jīng)細(xì)胞，這種被稱為“興奮”傳感器的神經(jīng)細(xì)胞可以在氧氣環(huán)境中持續(xù)產(chǎn)生應(yīng)答,。利用遺傳學(xué)工具,，他們發(fā)現(xiàn)了這種神經(jīng)細(xì)胞中興奮信號產(chǎn)生的分子機(jī)制以及興奮信號是如何傳遞給下游神經(jīng)細(xì)胞以引發(fā)短時(shí)或長時(shí)行為的。（生物谷 bioon.com ）
doi:10.1038/nn.3061
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Tonic signaling from O2 sensors sets neural circuit activity and behavioral state
Karl Emanuel Busch, Patrick Laurent, Zoltan Soltesz, Robin Joseph Murphy, Olivier Faivre, Berthold Hedwig, Martin Thomas, Heather L Smith,，Mario de Bono
Tonic receptors convey stimulus duration and intensity and are implicated in homeostatic control. However, how tonic homeostatic signals are generated and how they reconfigure neural circuits and modify animal behavior is poorly understood. Here we show that Caenorhabditis elegans O2 -sensing neurons are tonic receptors that continuously signal ambient [O2] to set the animal's behavioral state. Sustained signaling relied on a Ca2+ relay involving L-type voltage-gated Ca2+channels, the ryanodine and the inositol-1,4,5-trisphosphate receptors. Tonic activity evoked continuous neuropeptide release, which helps elicit the enduring behavioral state associated with high [O2]. Sustained O2 receptor signaling was propagated to downstream neural circuits, including the hub interneuron RMG. O2 receptors evoked similar locomotory states at particular O2 concentrations, regardless of previous d[O2]/dt. However, a phasic component of the URX receptors' response to high d[O2]/dt, as well as tonic-to-phasic transformations in downstream interneurons, enabled transient reorientation movements shaped by d[O2]/dt. Our results highlight how tonic homeostatic signals can generate both transient and enduring behavioral change.
