1. The transduction pathways of sweet-sensitive cells in rat circumvallate (CV) taste buds were investigated with assays for inositol 1,4,

The carbohydrate chains of glycolipids and glycoproteins at the cell surface are known to undergo many rapid changes during embryogenesis. These developmental changes include (a) alteration of branching structure in lactoseries carbohydrate chains, identified as I/i interconversion (1), (b) modification of terminal chains, responsible for the transition from Ii to ABH or SSEA-1 (reviewed in 2), (c) transition of globoseries antigen expression through pk, p, and Forssman (3), and (d) switching of core structure synthesis from one series to another, such as SSEA-3 ÷ globoseries to SSEA-1 + lactoseries (4). Although these structural changes have been defined clearly using various monoclonal antibodies, their physiological significance is unclear.The appearance of SSEA-1 on the embryo surface after the third cleavage division correlates approximately in time with the onset of compaction (5). During compaction, blastomeres maximize their intercellular contacts and generate a polar distribution of microvilli (6). Identification of SSEA-1 as the X hapten (Gall31 ---* 4[Fucal --0 3]GIcNAcI31 ~ R) (7-9) suggested the possibility of a 3-fucosyl-N-acetyllactosamine recognition system in the early mouse embryo. To test this hypothesis, we have studied the effect of lacto-N-fucopentaose III, its analogues, and their multivalent lysyllysine conjugates on compaction. Materials and Methods Purification of Oligosaccharides.A mixture of lacto-N-fucopentaose (LNFP) I, II, and III was obtained from human milk by the method of Kobata (10). LNFP I, II, and III (unreduced) were separated after acetylation by preparative thin-layer chromatography on HPTLC plates (J. T. Baker Chemical Co., Phiilipsburg, NJ) using a solvent system of butylacetate-acetone-water (25:8:1). After deacetylation, purified pentasaccharides were lyophilized and stored at -20 ° C. Chitotriose (GlcNAcI31 --~ 3GlcNA031 ---, 3GIcNAc) was a gift from Professor Toshiaki Osawa, University of Tokyo.Covalent Attachment of Oligosaccharides to LysyUysine.

A BSTR A CT Free phenolic acids may be the precursors for vinyl phenols and off-flavours

No abstract

Sucrose and other saccharides, which produce an appealing taste in rats, were found to significantly stimulate the activity of adenylate cyclase in membranes derived from the anterior-dorsal region of rat tongue. In control membranes derived from either tongue muscle or tongue non-sensory epithelium, the effect of sugars on adenylate cyclase activity was either much smaller or absent. Sucrose enhanced adenylate cyclase activity in a dose-related manner, and this activation was dependent on the presence of guanine nucleotides, suggesting the involvement of a GTP-binding protein ('G-protein'). The activation of adenylate cyclase by various mono- and di-saccharides correlated with their electrophysiological potency. Among non-sugar sweeteners, sodium saccharin activated the enzyme, whereas aspartame and neohesperidin dihydrochalcone did not, in correlation with their sweet-taste effectiveness in the rat. Sucrose activation of the enzyme was partly inhibited by Cu2+ and Zn2+, in agreement with their effect on electrophysiological sweet-taste responses. Our results are consistent with a sweet-taste transduction mechanism involving specific receptors, a guanine-nucleotide-binding protein and the cyclic AMP-generating enzyme adenylate cyclase.