Flip-Flop回路調(diào)節(jié)線蟲行為示意圖。(a) 相互拮抗的感覺信號(hào)輸入調(diào)節(jié)進(jìn)食行為的回路示意圖,，實(shí)線表示神經(jīng)元之間直接連接，虛線表示間接連接,。(b) 感覺信號(hào)調(diào)節(jié)進(jìn)食的回路與Flip-Flop電路對(duì)比。
4月10日,，國(guó)際著名雜志《自然-通訊》Nature Communications在線發(fā)表了中國(guó)科學(xué)院生物物理研究所徐濤課題組最新研究成果：感覺信號(hào)調(diào)控線蟲進(jìn)食行為的中樞翻轉(zhuǎn)回路解析（Dissecting a central flip-flop circuit that integrates contradictory sensory cues in C. elegans feeding regulation）,。該研究在秀麗隱桿線蟲（Caenorhabditis elegans）中發(fā)現(xiàn)了一種新的調(diào)控線蟲抉擇行為的神經(jīng)回路模式。
當(dāng)面臨兩難局面時(shí),，人或高等動(dòng)物能權(quán)衡利弊,，做出最有利的選擇。在這個(gè)過程中,，中樞神經(jīng)系統(tǒng)整合不同甚至完全相反的感覺輸入信號(hào),，決定生物個(gè)體行為抉擇。感覺輸入信號(hào)的整合對(duì)生物的生存至關(guān)重要,，但其背后的分子機(jī)制如何仍不清楚,。
線蟲具有神經(jīng)系統(tǒng)的組成相對(duì)簡(jiǎn)單（共118類302個(gè)神經(jīng)元）和遺傳操作便捷的優(yōu)勢(shì),，徐濤課題組發(fā)現(xiàn)，線蟲可以用來(lái)研究相互拮抗的感覺輸入是如何最終影響個(gè)體行為抉擇的,。他們采用兩種化學(xué)物質(zhì)——雙乙酰酮和奎寧來(lái)同時(shí)刺激線蟲,。這兩種物質(zhì)分別通過線蟲的嗅覺和味覺通路輸入，對(duì)線蟲進(jìn)食行為的影響恰好相反：雙乙酰酮增加進(jìn)食,，奎寧抑制進(jìn)食,。
結(jié)合遺傳學(xué)方法及活體鈣成像技術(shù)，研究證實(shí),，兩路跨模態(tài)的感覺輸入的整合具有“勝者全得” （winner-takes-all）的特性,，其產(chǎn)生的機(jī)制依賴線蟲咽部神經(jīng)元NSM和咽外神經(jīng)元RIM/RIC組成的一個(gè)相互抑制的中樞神經(jīng)回路來(lái)實(shí)現(xiàn)。研究人員進(jìn)而鑒定了介導(dǎo)互相抑制的分子回路,。這樣一種中樞的整合機(jī)制非常類似電子線路中的翻轉(zhuǎn)（flip-flop）電路,，可以保證較強(qiáng)的輸入信號(hào)得到放大而使微小的信號(hào)得到過濾，從而使線蟲的行為輸出具有穩(wěn)定性,。（生物谷Bioon.com）
doi:10.1038/ncomms1780
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Dissecting a central flip-flop circuit that integrates contradictory sensory cues in C. elegans feeding regulation
Zhaoyu Li, Yidong Li, Yalan Yi, Wenming Huang, Song Yang, Weipin Niu, Li Zhang, Zijing Xu, Anlian Qu, Zhengxing Wu & Tao Xu
Feeding behaviour is modulated by both environmental cues and internal physiological states. Appetite is commonly boosted by the pleasant smell (or appearance) of food and destroyed by a bad taste. In reality, animals sense multiple environmental cues at the same time and it is not clear how these sensory inputs are integrated and a decision is made to regulate feeding behaviour accordingly. Here we show that feeding behaviour in Caenorhabditis elegans can be either facilitated by attractive odours or suppressed by repellents. By identifying mutants that are defective for sensory-mediated feeding regulation, we dissected a central flip-flop circuit that integrates two contradictory sensory inputs and generates bistable hormone output to regulate feeding behaviour. As feeding regulation is fundamental to animal survival, we speculate that the basic organizational logic identified here in C. elegans is likely convergent throughout different phyla.
