HYPHAL WALL CHEMISTRY OF LAGENIDIUM-CALLINECTES AND LAGENIDIUM-CHTHAMALOPHILUM

The chemical composition of mechanically isolated hyphal walls of the marine fungi Lagenidium callinectes and Lagenidium chthamalophilum was determined using biochemical, cytochemical, and x-ray diffraction analysis. In both fungi, the primary wall constituents were beta-glucans, containing predominately (1 --> 3)- and (1 --> 6)-linked glucosyl residues; glucan accounted for 79% of wall dry weight in L. callinectes and 66% of wall dry weight in L. chthamalophilum. Cellulose was demonstrated by cytochemical and x-ray diffraction analysis and accounted for 7.8% and 7.5% of wall dry weight in L. callinectes and L. chthamalophilum, respectively. Additionally, hyphal walls contained mannose, protein, ash (inorganic), and lipid. Respectively, these constituents were found to account for 0.7%, 5.4%, 3.5%, and 5.8% of wall dry weight in L. callinectes and 2.7%, 9.8%, 2.9%, and 8.2% of wall dry weight in L. chthamalophilum. Although glucosamine was detected in wall hydrolysates of L. callinectes and L. chthamalophilum and accounted for 0.7% and 2.1 %, respectively, no evidence for the presence of chitin in hyphal walls was observed. The hyphal wall composition in these two species of the Order Lagenidiales is quite similar to that reported for other oomycetes. Both L. callinectes and L. chthamalophilum parasitize a variety of invertebrates including crabs, lobsters, barnacles, and shrimp. It is suggested that an understanding of cell wall composition in these parasitic fungi might be useful in better understanding the Lagenidium cell surface, which would prove helpful in assessing the complex interaction between the cell surfaces of the parasite and its host.