Synthesis of the starfish ganglioside LLG-3 tetrasaccharide

The first synthesis of the ganglioside LLG-3 tetrasaccharide, which has attractive biological activities as well as a unique structure, is described. A C8-methoxy decorated sialic acid building block was initially prepared and a glycolic acid moiety was then introduced by sialylation. Amide condensation between the sialyl glycolic acid and an amino group at C5 on the sialyllactoside unit afforded the fully protected LLG-3 tetrasaccharide. Finally, the desired tetrasaccharide part of LLG-3 was obtained after careful global deprotection.     

Mouse sperm lacking cell surface hyaluronidase PH-20 can pass through the layer of cumulus cells and fertilize the egg

The function of glycosylphosphatidylinositol-anchored sperm hyaluronidase PH-20 in fertilization has long been believed to enable acrosome-intact sperm to pass through the layer of cumulus cells and reach the egg zona pellucida. In this study, we have produced mice carrying a null mutation in the PH-20 gene using homologous recombination. Despite the absence of sperm PH-20, the mutant male mice were still fertile. In vitro fertilization assays showed that mouse sperm lacking PH-20 possess a reduced ability to disperse cumulus cells from the cumulus mass, resulting in delayed fertilization solely at the early stages after insemination. Moreover, SDS-PAGE of sperm extracts and subsequent Western blot analysis revealed the presence of other hyaluronidase(s), except PH-20, presumably within the acrosome of mouse sperm. These data provide evidence that PH-20 is not essential for fertilization, at least in the mouse, suggesting that the other hyaluronidase(s) may play an important role in sperm penetration through the cumulus cell layer and/or the egg zona pellucida, possibly in cooperation with PH-20, although the importance of sperm motility cannot be neglected.     

Structural studies reveal that the diverse morphology of beta(2)-microglobulin aggregates is a reflection of different molecular architectures

Amyloid deposition accompanies over 20 degenerative diseases in human, including Alzheimer's, Parkinson's, and prion diseases. Recent studies revealed the importance of other type of protein aggregates, e.g., non-specific aggregates, protofibrils, and small oligomers in the development of such diseases and proved their increased toxicity for living cells in comparison with mature amyloid fibrils. We carried out a comparative structural analysis of different monomeric and aggregated states of beta(2)-microglobulin, a protein responsible for hemodialysis-related amyloidosis. We investigated the structure of the native and acid-denatured states, as well as that of mature fibrils, immature fibrils, amorphous aggregates, and heat-induced filaments, prepared under various in vitro conditions. Infrared spectroscopy demonstrated that the beta-sheet compositions of immature fibrils, heat-induced filaments and amorphous aggregates are characteristic of antiparallel intermolecular beta-sheet structure while mature fibrils are different from all others suggesting a unique overall structure and assembly. Filamentous aggregates prepared by heat treatment are of importance in understanding the in vivo disease because of their stability under physiological conditions, where amyloid fibrils and protofibrils formed at acidic pH depolymerize. Atomic force microscopy of heat-induced filaments represented a morphology similar to that of the low pH immature fibrils. At a pH close to the pI of the protein, amorphous aggregates were formed readily with association of the molecules in native-like conformation, followed by formation of intermolecular beta-sheet structure in a longer time-scale. Extent of the core buried from the solvent in the various states was investigated by H/D exchange of the amide protons.     

Central administration of phosphatidylserine attenuates isolation stress-induced behavior in chicks

The present study investigated whether centrally administered phosphatidylserine (PS) could modify the behavior of chicks under isolation-induced stress. Isolation stress-induced vocalization and spontaneous activity for 10 min, which were attenuated by intracerebroventricular (i.c.v.) injection of PS. The effect of PS was compared with other phospholipids or L-serine, a constituent of PS. Phosphatidylcholine (PC) had no effect on these behavior, but phosphatidylethanolamine (PE) significantly increased vocalizations and spontaneous activity compared with PS. L-Serine similarly decreased isolation-induced vocalizations and spontaneous activity. To clarify the mechanism by which central PS attenuates isolation-induced stress behavior, the contribution of the acetylcholine (ACh) receptor (AChR) was also investigated. PS was co-injected i.c.v. with the muscarinic AChR (M-AChR) antagonist scopolamine or the nicotinic AChR (N-AChR) antagonist hexamethonium. The suppression of vocalizations and spontaneous activity by PS was partially attenuated by scopolamine, but not hexamethonium. These findings indicate that isolation-induced stress behavior are attenuated by PS, acting partially through the M-AChR.