Meeting Abstract

P3.173  Tuesday, Jan. 6  Investigations of structural dynamics during bleaching in two species of anemone, Aiptasia pallida and A. pulchella. HANES, S.D.*; KEMPF, S.C.; Auburn University; Auburn University hanessd@auburn.edu

Bleaching involves the loss of symbiotic algae from cnidarian tissues and may be a combined stress response of host and algae. There is little known of structural changes that occur at the interface between symbiont-containing endodermal cells and surrounding tissues during the bleaching process. In this study, light and transmission electron microscopy are utilized to examine histology/ultrastructure of two model organisms, Aiptasia pallida and A. pulchella under both symbiotic and aposymbiotic conditions. Histological observations reveal that symbiont-containing, endodermal epithelium exhibits either simple cuboidal or columnar cell types, varying at different locations within the anemone. Alternatively, aposymbiotic anemones display simple, cuboidal endodermal cells throughout, but further ultrastructural examination is necessary. These results suggest that different regions within the anemone are lined with different types of epithelial cells, and may indicate that metaplasia, or cell type transformation, is occurring. Additionally, factors such as symbiont number and/or external conditions (i.e. light intensity) may influence epithelial type and possible cellular transitions. Preliminary ultrastructural results indicate the presence of previously undescribed cells or cell processes, located between the basal host endodermal cell membrane and the mesogleal layer. This suggests that reported host cell detachment during bleaching involves more than simple release from the mesoglea. Future investigations will be conducted to progressively examine endodermal epithelia while thermal bleaching occurs.