The P.I. will determine the prevalence of chitan and other chitins in primary production. Major phytoplankton taxa will be screened for chitan production. Chitin-positive phytoplankton in addition to the known chitan producers, Thalassiosira and Cyclotella, will be studied in depth to determine the physiological conditions relevant for chitin or chitan production. Seasonal trends in the seasonal significance of this new biogeochemical polymer, chitan, will be monitored at a mid- Chesapeake Bay site. Diel variance will be evaluated twice annually at this site and once in the second year at the Bermuda Times Series Station. A new biochemical fractionation step will be developed in course of this work, which will permit resolution of the interference that chitan has in the conventional trichloroacetic acid protein precipitation step used in previous studies. Efficacy of the new extraction procedures will be dtermined by specific HPLC-linked enzyme hydrolyses and HPLC and planar (TLC) analyses of amino acids, amino sugars, reducing sugars. Radiocarbon budgets with discrimination of individual sugars, amino sugars and amino acids will be accomplished with the aid of an imaging proportional counter designed for automatically and quantitatively mapping radioisotopes on TLC plates.
