The antennules of calanoid copepods compose one of the primary organs for remote sensing of mechanical and chemical environmental stimuli. To better understand how these sensory structures interface with the 3-dimensional fluid environment, it is necessary to understand both their functional morphology and their physiology. These appendages possess setae which are the suspected sites of signal transductlon. Ultrastructural studies reveal that the setae differ in their patterns of innervat~on, and it is believed that these dissimilarities reflect differences in function. In this study, we label the sensilla of copepod antennules using a fluorescent carbocyanine dye, Dil, which becomes inserted in the lipid bilayer of neuronal cell membranes. Aesthetascs on the antennules can then be identified using standard fluorescent microscopy. Because the copepod exoskeleton is transparent to the laser, we were able to utilize laser scanning confocal microscopy to identify other neuronal structures and patterns of musculature within the antennule, while simultaneously visualizing the orientation and larger scale structure of the sensilla.

A 1-MHz continuous wave sound field of intensity 0.6 W/cm2 was applied to a suspension of avian erythrocytes in vitro for 30 min. Total uptake (diffusion plus nonspecific binding plus mediated transport) was determined by incubation of 1-ml aliquots of insonated and control cells for 10 min in labeled leucine. The percentage of the total uptake due to mediated transport was determined by a similar incubation in a 50:1 mixture of the competitive inhibitor isoleucine and labeled leucine. At the intensities used the sonated cells absorbed approximately 5% less labeled leucine than the control cells. Analysis shows the effect to be statistically significant (P < 0.01). However, results for the effect of ultrasound on mediated transport are not statistically significant (P > 0.9). Therefore, the greatest effect of ultrasound using these experimental conditions is on the diffusion component of transport. [This work was supported in part by the American Heart Association-Maine Affiliate, NIH via AM 19445 and the Maine State Experiment Station.]

No abstract