Worm Breeder's Gazette 12(3): 116 (June 15, 1992)

These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.

Towards Genetic Understanding of Habituation in C. elegans

R. Hosono

Department of Biochemistry, School of Medicine,Kanazawa University, Kanazawa, Ishikawa 920 Japan

As in other organisms, the information on sensory receptors of C. elegans are received and integrated at the central nervous system. Elucidation of the processes of learning will facilitate the understanding of neural integration. We adopted habituation, a non-associative learning process, for the work.

We can recognize habituation in several types of C. elegans behavior. For example, when we open the cap of a dish, the animals show active movement, but cease to move by the repeated opening. Animals promptly escape, by strolling the tip of an eyebrow hair transversely across the anterior half of animal but ceased the avoidance response by repeated touching. Habituation in tap withdrawal reflex is already reported by Rankin et al.(Behav. Brain Res., 37 89 '90).

The genetic background of habituation is scarcely known. We have undertaken a study to identify and characterize genes contributing habituation behavior. Our current goal is not to find genes that act for a specific type of behavior but genes necessary for any behavior. Therefore, we adopted two different types of screening for habituation-defective mutants: Tap response and touch response. Tap response abnormals

In our tap apparatus, animals move backwards for 24 sec by a single tap but 412 sec by repeated tapping. After training with 200 taps for 30 sec, mutants continuing backward movement under 1.3 taps per sec were screened. EMS-mutagenized 5 F1 animals were put onto a NGM plate and allowed to produce F2 .From approximately 600 plates, five independent potential mutants were isolated by the the tap screening. Of these five, one is completely defective, that is, the mutant continues tap- withdrawal response during the tap stimuli and the remainings are partially defective.

Touch response abnormals

Animals continue to move backwards for 2-6 sec by a single slight touch at the anterior region but recover forward movement when repeatedly touched 10-30 times. We screened mutants not recovering their forward movement irrespective of repeated touch after 30 times. I stopped in the midst of the screening procedure because the work was tedious, though the screening procedure was simple. We are now performing extensive isolations of the tap response abnormals and hope to find mutants from them defective in touch response that may be defective in habituation.

Acknowledgement: Rankin showed me her tap apparatus and suggested the analyses of tap stimulated behavior.

Literature Cited:

Rankin et al.. Behav. Brain Res., 37 89 '90