Department of Biotechnology
inStem (Institute for Stem Cell Science and Regenerative Medicine)

Discovery of a body-wide photosensory array that matures in an adult-like animal and mediates eye-brain-independent movement and arousal.

Publication Type

Journal Article

Date of Publication

May 18, 2021

Journal

Proceedings of the National Academy of Sciences of the United States of America

Volume/Issue

118/20

ISSN

1091-6490

The ability to respond to light has profoundly shaped life. Animals with eyes overwhelmingly rely on their visual circuits for mediating light-induced coordinated movements. Building on previously reported behaviors, we report the discovery of an organized, eye-independent (extraocular), body-wide photosensory framework that allows even a head-removed animal to move like an intact animal. Despite possessing sensitive cerebral eyes and a centralized brain that controls most behaviors, head-removed planarians show acute, coordinated ultraviolet-A (UV-A) aversive phototaxis. We find this eye-brain-independent phototaxis is mediated by two noncanonical rhabdomeric opsins, the first known function for this newly classified opsin-clade. We uncover a unique array of dual-opsin-expressing photoreceptor cells that line the periphery of animal body, are proximal to a body-wide nerve net, and mediate UV-A phototaxis by engaging multiple modes of locomotion. Unlike embryonically developing cerebral eyes that are functional when animals hatch, the body-wide photosensory array matures postembryonically in “adult-like animals.” Notably, apart from head-removed phototaxis, the body-wide, extraocular sensory organization also impacts physiology of intact animals. Low-dose UV-A, but not visible light (ocular-stimulus), is able to arouse intact worms that have naturally cycled to an inactive/rest-like state. This wavelength selective, low-light arousal of resting animals is noncanonical-opsin dependent but eye independent. Our discovery of an autonomous, multifunctional, late-maturing, organized body-wide photosensory system establishes a paradigm in sensory biology and evolution of light sensing.

Alternate Journal

Proc Natl Acad Sci U S A

PubMed ID

33941643

PubMed Central ID

PMC8157970

Authors

Nishan Shettigar
Anirudh Chakravarthy
Suchitta Umashankar
Vairavan Lakshmanan
Dasaradhi Palakodeti
Akash Gulyani

Keywords

RNA Interference
Gene Expression Profiling
Phylogeny
Helminth Proteins
Animals
Arousal
In Situ Hybridization, Fluorescence
Brain
Locomotion
Gene Expression Regulation, Developmental
Movement
Opsins
Eye
Photoreceptor Cells, Invertebrate
Planarians
Ultraviolet Rays