Chemical synthesis of UDP-4-O-methyl-GlcNAc, a potential chain terminator of chitin synthesis

Chitin synthase converts uridine diphosphoryl-N-acetylglucosamine (UDP-GlcNAc) to chitin (poly-beta-(1-->4)-GlcNAc). During polymerization, elongation occurs at the 4-OH (nonreducing) terminus of the growing chitin chain. Blockage of the 4-OH via incorporation of UDP-N-acetyl-4-O-methylglucosamine (UDP-4-OMe-GlcNAc, 3) can potentially terminate chitin polymerization, and represents a novel strategy for chitin synthase inhibition. The chemical synthesis of 3 and preliminary evaluation of its possible incorporation by chitin synthase are reported herein.     

Anomalous Westerlies, El Niño, and the Colonization of Polynesia

The west to east migration of the Polynesians and their Lapita predecessors was not accomplished by tacking against the prevailing southeast trade winds, but by using periodic westerly wind reversals to sail eastward. Data on equatorial westerlies and associated ocean current effects, including those gathered during recent El Niño events, are presented to indicate how these canoe voyagers were able to migrate so far into the Pacific.