Yang Xiang received his B.S. in Biochemistry from Nanjing University in 1999. He carried out his doctoral training in the laboratory of Dr. Mu-ming Poo at the institute of Neuroscience, Chinese Academy of Sciences, where he studied axonal guidance, obtained his Ph.D in Neurobiology in 2003. Yang Xiang then received the Human Frontiers Science Program fellowship to work as a postdoctoral associate with Dr. Yuh-Nung Jan at HHMI, University of California San Francisco from 2004-2012, studying sensory neuron function in Drosophila. He started his laboratory in the Department of Neurobiology at The University of Massachusetts Medical School in 2012.
Molecular and neural circuit mechanisms underlying behavior
Our lab is interested in understanding how the nervous system detects and processes sensory stimuli to generate appropriate behavior, a central question in neurobiology. We work on the genetically tractable organism Drosophila. Specifically, our research focuses on the innate escape behavior triggered by harmful light in Drosophila larvae. We found that a specific class of sensory neurons (namely, class IV dendritic arborization (da) neurons) are novel photoreceptors activated by intense harmful short wavelength light, with spectral sensitivity UV>violet>blue>>green~red, and mediate larval escape behavior when illuminated by UV, violet and blue light. Classical phototransduction molecules are not required in class IV da neurons. Instead, gustatory receptor 28b (Gr28b), G protein signaling and dTRPA1 are critical. Beyond harmful light, class IV da neurons also sense noxious heat (>40oC) and the irritant chemical AITC, a major component of wasabi.
Applying molecular genetics, GCaMP-based functional imaging, electrophysiology, and behavioral assay, our goal is to dissect the molecular, cellular and neural circuit mechanisms underlying sensory stimuli-induced behavior in Drosophila larvae. Specifically, we aim to (1) identify the phototransduction mechanism in class IV da neurons; (2) define and characterize the neural circuits underlying light-induced escape behavior.
People in the lab
Pengyu Gu, Ph.D.(Nanjing University)
Kendra Takle, B.S.(University of Wisconsin, Madison)
Figure 1 Dorsal view of a 3rd instar Drosophila larva (5 mm in length) with class IV da neurons marked by ppk-CD4TdGFP. en-GAL4 in red marks the posterior epidermal cells of each segment. Each larva has 11 segments and there are 3 class IV da neurons in each hemi-segment. Dendrites of class IV da neurons cover the entire larval body wall in a complete but non-overlapping fashion, a phenomenon called dendritic tiling. This organization will ensure that larvae can detect strong harmful light exposure over their entire bodies. (Image Credit: Dr. Chun Han, UCSF)
Figure 2 class IV da neurons detect harmful UV to initiate the escape behavior. Our working model is that Gr28b absorbs photon, and leads to dTRPA1 channels opening and action potential firing in class IV da neurons. Electrical signals encoded by class IV da neurons will be decoded by neural circuits in the CNS into escape behavior.
Movie 1 Upon 5 s light stimulation of the anterior region (0.57 mW/mm2 white light, comparable to sunlight intensity), a 3rd instar larva of wt (left) exhibits avoidance behavior, while a larva with class IV da neurons genetically ablated (right) doesn’t avoid light.
Movie 2 Class IV da neurons are specifically activated by UV (365 nm) and blue (470 nm), but not green (546 nm) light. Shown here are larval peripheral sensory neurons in a dorsal cluster expressing GCaMP3, with the arrow pointing to the class IV da neuron. 5 s light stimulation is indicated in the upper-right corner. GCaMP3 fluorescence is marked by pseudo-color, with red indicating high and blue indicating low intensity. Similar light activation of class IV da neurons is observed in lateral and ventral clusters across the entire larval body wall.