Meeting Abstract
Most organisms express circadian (24-hour) rhythms of behavior, such as the locomotor patterns exhibited by the nudibranch mollusc Melibe leonina. CLOCK is an important protein underlying circadian rhythms, and its amino acid sequence in Melibe has been determined, facilitating the development of a custom antibody to CLOCK. In this study, brains were removed from animals at 9am and 9pm and immunohistochemistry was done to localize neurons containing CLOCK. Labeling was consistently seen in eight individually identifiable neurons in three locations of the brain: 1) the buccal ganglia, 2) below each eye, and 3) to the left and right of the midline of the cerebropleural ganglia. The number of labeled neurons, and the intensity of fluorescence, was similar between night and day samples, indicating a potential lack of fluctuation in the abundance of CLOCK throughout the day. This evidence suggests that the circadian clock in Melibe is relegated to only a small number of individually identifiable neurons, facilitating future studies of circadian rhythms in this animal.
