Dissolved Protein Uptake in the Larvae of Shallow Water and Deep Water Echinoderms

The ability of several subtropical echinoderm larvae to absorb large, dissolved organic molecules was assessed by exposing them to FITC-BSA and Ferritin. We tested shallow water auricularia and pentacula from unknown species, plutei from the shallow water Tripneustes sp. and deep water Cidaris blakei blastula and gastrula. Once larvae had been exposed for several hours, FITC-BSA treated larvae were examined under an epifluorescent compound microscope and compared with the control treatment. Auricularia demonstrate uptake ofFITC-BSA mainly in the stomach and intestines. Lower levels of epifluorescence in other cells indicates initial uptake in the endoderm and subsequent transport to other parts of the larva. Pentacula larvae were labeled throughout the animals and the location of uptake cannot be deciphered until the ferritin treatments are analyzed. Tripneustes sp. larvae demonstrated FITC-BSA uptake primarily in the stomach and intestine, with small amounts visible in the remaining parts of the organism, suggesting a similar uptake method as the auricularia larvae. C. blakei blastula demonstrated a large amount of uptake in epidermis despite the lack of endoderm. Ectodermic absorption of large proteins in largely unheard of in the literature. C. blakei gastrula demonstrated similar uptake patterns with large amounts ofFITC-BSA visible in the ectoderm. Absorption in the archinteron was not resolved and awaits con-focal microscopy.