An analysis of the tap withdrawal response in male caenorhabditis elegans

Kim Bill Mah
The nematode, Caenorhabditis elegans, displays sexual dimorphism; males arise by the process of x-chromosome nondisjunction. The male is differentiated from the hermaphrodite by the addition of 14 sensory structures in the tail, as well as by the total complement of neurons. The male possesses 381 neurons of which at least 87 are male specific, compared with a total of 302 neurons in the hermaphrodite. The purpose of this thesis was to investigate whether the additional sensory and neural
more » ... try in the male resulted in a difference in the tap withdrawal response in male C. elegans compared to that of the hermaphrodite. First, the basal activity level of males was compared to that of hermaphrodites. Males exhibited significantly more spontaneous reversals than hermaphrodites', these reversals were categorized as true spontaneous reversals and self-feeling reversals. The reversal magnitude of true spontaneous reversals did not differ across sex, however the magnitude of self-feeling reversals was significantly greater in males compared to hermaphrodites. Next, the reflexive reversal response to tap was examined. Both males and hermaphrodites exhibited a graded magnitude of response to an increasing number of taps. Males, however, showed an increasing incidence of accelerations as tap number increased, while hermaphrodites showed the same number of reversals as the number of taps increased. In response to taps of increasing intensity, both males and hermaphrodites showed an increase in reversal magnitude. Response magnitudes exhibited by males were significantly greater than those of hermaphrodites. The interaction between two antagonistic reflexes was then examined. A tail-touch followed by a tap 1 s later significantly inhibited both the number and size of the reversal response in males and hermaphrodites. There were no significant sex differences at any tail-touch/tap intervals tested, although the hermaphrodites exhibited facilitation at the 20 and 30 s tail-touch/tap interval. The administration of 25 t [...]
doi:10.14288/1.0100715 fatcat:ekotml3esng7rd2w54nmqts2uq