In vivo calcium imaging of OFF-responding ASK chemosensory neurons in C. elegans.
BACKGROUND
How neurons and neuronal circuits transform sensory input into behavior is not well understood. Because of its well-described, simple nervous system, Caenorhabditis elegans is an ideal model organism to study this issue. Transformation of sensory signals into neural activity is a crucial first step in the sensory-motor transformation pathway in an animal's nervous system. We examined the properties of chemosensory ASK neurons of C. elegans during sensory stimulation.


METHODS
A genetically encoded calcium sensor protein, G-CaMP, was expressed in ASK neurons of C. elegans, and the intracellular calcium dynamics of the neurons were observed.


RESULTS
After application of the attractants l-lysine or food-related stimuli, the level of calcium in ASK neurons decreased. In contrast, responses increased upon stimulus removal. Opposite responses were observed after application and removal of a repellent.


CONCLUSIONS
The observed changes in response to external stimuli suggest that the activity of ASK neurons may impact stimulus-evoked worm behavior. The stimulus-ON/activity-OFF properties of ASK neurons are similar to those of vertebrate retinal photoreceptors.


CONCLUSIONS
Analysis of sensory-motor transformation pathways based on the activity and structure of neuronal circuits is an important goal in neurobiology and is practical in C. elegans. Our study provides insights into the mechanism of such transformation in the animal.
Laboratory of Bioscience, Faculty of Engineering, Iwate University, 4-3-5 Ueda, Morioka, Iwate 020-8551, Japan.
Tokumitsu
T
Wakabayashi
Yukihiro
Y
Kimura
Yusuke
Y
Ohba
Ryota
R
Adachi
Yoh-Ichi
Y
Satoh
Ryuzo
R
Shingai
D000818:Animals; D030801:Animals, Genetically Modified; D001419:Bacteria; D017173:Caenorhabditis elegans / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D017077:Culture Media, Conditioned; D021621:Imaging, Three-Dimensional / Q000379:methods*; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D008239:Lysine / Q000494:pharmacology; D011984:Sensory Receptor Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D012967:Sodium Dodecyl Sulfate / Q000494:pharmacology
D017077:Culture Media, Conditioned; D012967:Sodium Dodecyl Sulfate; D008239:Lysine; D002118:Calcium