Meeting Abstract

P2.24  Sunday, Jan. 5 15:30  ULTRASTRUCTURAL ANALYSIS DEMONSTRATES THAT THE NUDIBRANCH MELIBE LEONINA LACKS SYMBIOTIC ALGAE AND KLEPTOPLASTS KALLINS, M.G.*; CURTIS, N.E.; PIERCE, S.K.; WATSON III, W.H.; NEWCOMB, J.M.; Rollins College; Rollins College; University of South Florida; University of New Hampshire; New England College MKALLINS@Rollins.edu

The nudibranch, Melibe leonina (Gould 1852), is found in kelp or eel grass beds along the Pacific coast of North America. This slug feeds using a unique oral hood to capture planktonic organisms, mostly copepods and amphipods according to gut content analysis. However, examination of the digestive diverticula of cerata from M. leonina by confocal microscopy (480 nm ) demonstrated intensely autofluorescing circular structures within the cells lining the lumen, possibly indicating the presence of chlorophyll containing structures such as symbiotic zooxanthellae or sequestered chloroplasts. Thus, careful transmission electron microscopy (TEM) was conducted to determine the contents of cells in the cerata. There was no evidence of chloroplasts or symbiotic algae in or near the digestive gland cells of the cerata of M. leonina. The cells contained structures typical of molluscan digestive gland cells such as heterolysosomes, residual bodies, and other phagosome-like bodies, and it is suspected that these structures are responsible for the autoflourescence.