Tangential cell migration during layer formation of chick optic tectum

The laminated structure of the optic tectum is formed by radial and tangential cell migration during development. Studies of developing chick optic tectum have revealed two streams of tangential cell migration in the middle and superficial layers, which have distinctive origins, migratory paths, modes of migration, and destinations. We will review the process of the two types of tangential migrations, in order to elucidate their roles in the formation of the optic tectum layers.     

Recent Advances in the use of Immobilized Lipases Directed Toward the Asymmetric Syntheses of Complex Molecules

Water-insoluble compounds can be substrates for enzymatic reactions when lipases are immobilized properly and suitable organic solvents are used. In this review, three type of lipase immobilization method and their application to the asymmetric syntheses of complex molecules are described. Lipases immobilized with Celite or synthetic prepolymers such as urethane prepolymer and photo-crosslinkable resin prepolymer have been applied for the kinetic resolution of many kinds of water-insoluble substrate.

Phospholipid-lipase aggregates with ether linkages are novel and have been found to function effectively as immobilized lipases in asymmetric hydrolysis or esterification reactions in water-saturated organic solvent. The phospholipid-lipase aggregates are considered to have a stacked bilayer based on X-ray diffraction analysis structure of the lipid in the crystalline phase.     

Stability of 3' dangling ends on the core helix of AUGCAU at various Na+ concentrations.

Stability increments of 3' dangling ends on the core helices AUGCAU at various Na+ concentrations are reported. The results show that all 3' dangling ends except 3'U dangling at low Na+ concentrations can stabilize the helix and this stabilization is very sequence dependent.     

Molecular and Biochemical Characterization of Three Anthocyanin Synthetic Enzymes from Gentiana triflora

Full length cDNA clones of flavonoid 3',5'-hydroxylase, dihydroflavonol4-reductase and flavonoid 3-glucosyltransferase were clonedfrom petals of Gentiana triflora. Their sequences were homologousto counterparts from other plants. Flavonoid 3',5'-hydroxylaseand flavonoid 3-glucosyltransferase were enzymatically characterizedby expressing cDNAs in heterologous expression systems. (Received May 21, 1996; Accepted June 4, 1996)     

Quantitative detection of bisphenol A and bisphenol A diglycidyl ether metabolites in human plasma by liquid chromatography–electrospray mass spectrometry

Due to the ubiquity of epoxy resin compounds and their potential role in increasing the risk for reproductive dysfunction and cancer, the need for an assessment of human exposure is urgent. Therefore, we developed a method for measuring bisphenol A (BPA) and bisphenol A diglycidyl ether (BADGE) metabolites in human blood samples using high-performance liquid chromatography–electrospray ionization mass spectrometry (LC–MS). Human blood samples were processed using enzymatic deconjugation of the glucuronides followed by a novel sample preparation procedure using a solid-phase-cartridge column. This selective analytical method permits rapid detection of the metabolites, free BPA and a hydrolysis product of BADGE (BADGE-4OH) with detection limits in the low nanogram per milliliter range (0.1 ng ml⁻¹ of BPA and 0.5 ng ml⁻¹ of BADGE-4OH). The sample extraction was achieved by Oasis HLB column on gradient elution. The recoveries of BPA and BADGE-4OH added to human plasma samples were above 70.0% with a standard deviation of less than 5.0%. This selective, sensitive and accurate method will assist in elucidating potential associations between human exposure to epoxy-based compounds and adverse health effects.     

A water channel of the nematode C.elegans and its implications for channel selectivity of MIP proteins

A genome project focusingon the nematode Caenorhabditis elegans has demonstrated thepresence of eight cDNAs belonging to the major intrinsic proteinsuperfamily. We functionally characterized one of these cDNAs namedC01G6.1. Injection of C01G6.1 cRNA increased the osmotic waterpermeability (P_f) of Xenopusoocytes 11-fold and the urea permeability 4.5-fold but failed toincrease the glycerol permeability. It has been speculated that the MIPfamily may be separated into two large subfamilies based on thepresence or absence of two segments of extra amino acid residues (~15amino acids) at the second and third extracellular loops. BecauseC01G6.1 (designated AQP-CE1), AQP3, and glycerol facilitator (GlpF) all have these two segments, we replaced the segments of AQP-CE1 with thoseof AQP3 and GlpF to identify their roles. The functional characteristics of these mutants were principally similar to that ofwild-type AQP-CE1, although the values of P_f andurea permeability were decreased by 39-74% and 28-65%,respectively. These results suggest that the two segments of extraamino acid residues may not contribute to channel selectivity orformation of the route for small solutes.