EMBL/CRG Systems Biology Unit, Center for Genomic Regulation (CRG) and UPF, 08003 Barcelona, Spain.
Nat Commun. 2011 Aug 23;2:441. doi: 10.1038/ncomms1455.
The ability to respond to chemical stimuli is fundamental to the survival of motile organisms, but the strategies underlying odour tracking remain poorly understood. Here we show that chemotaxis in Drosophila melanogaster larvae is an active sampling process analogous to sniffing in vertebrates. Combining computer-vision algorithms with reconstructed olfactory environments, we establish that larvae orient in odour gradients through a sequential organization of stereotypical behaviours, including runs, stops, lateral head casts and directed turns. Negative gradients, integrated during runs, control the timing of turns. Positive gradients detected through high-amplitude head casts determine the direction of individual turns. By genetically manipulating the peripheral olfactory circuit, we examine how orientation adapts to losses and gains of function in olfactory input. Our findings suggest that larval chemotaxis represents an intermediate navigation strategy between the biased random walks of Escherichia Coli and the stereo-olfaction observed in rats and humans.
对化学刺激做出反应的能力是运动生物生存的基础，但气味追踪背后的策略仍知之甚少。在这里，我们表明果蝇幼虫的趋化性是一种类似于脊椎动物嗅探的主动采样过程。我们结合计算机视觉算法和重建的嗅觉环境，确定幼虫通过一系列典型行为的顺序组织来在气味梯度中定向，包括奔跑、停止、侧向头部摆动和定向转弯。在奔跑过程中整合的负梯度控制转弯的时间。通过高幅度的头部摆动检测到的正梯度确定个体转弯的方向。通过遗传操纵外围嗅觉回路，我们研究了定向如何适应嗅觉输入功能的丧失和获得。我们的研究结果表明，幼虫的趋化性代表了大肠杆菌偏向随机游走和大鼠和人类观察到的立体嗅觉之间的一种中间导航策略。
