Isolation and characterization of microsatellite loci in the Bang's leaf‐nosed bat Hipposideros turpis

The Bang's leaf‐nose bat, Hipposideros turpis, is an endangered cave‐dwelling species inhabiting the southwesternmost islands of Japan. We isolated six dinucleotide microsatellite markers from the partial genomic library of the bat, and examined their allelic variation using a sample (N = 33) from the largest colony in Japan. All the loci showed a moderate allelic variation ranging from two to eight alleles, with the observed heterozygosities from 0.33 to 0.73, and conformed to Hardy–Weinberg expectations. The present microsatellite markers will be useful in assessing population genetic structure and gene flow among populations of this species.     

Role of water and electrolyte influxes in anoxic plasma membrane disruption

The role of water and electrolyte influxes in anoxia-inducedplasma membrane disruption was investigated using rabbit proximal tubule suspension. The results indicated that normal proximal tubule(PT) cells have a great capacity for expanding cell volume in responseto water influx, whereas anoxia increases the susceptibility to waterinflux-induced disruption, and this was attenuated by glycine. However,resistance of anoxic plasma membranes to water influx-induced stress isnot lost, although their mechanical strength was diminished, comparedwith normoxic membranes. Anoxic membranes did not disrupt under anintra-to-extracellular osmotic difference as great as 150 mosM.Potentiating or attenuating water influx by incubating PT cells inhypotonic or hypertonic medium, respectively, during anoxia, did notaffect anoxia-induced membrane disruption. After the transmembraneelectrolyte concentration gradient was eliminated by a"intracellular" buffer or by permeabilizing the plasma membraneto molecules <4 kDa using -toxin, anoxia still caused furthermembrane disruption that was prevented by glycine or low pH. Theseresults demonstrate that 1) water ornet electrolyte influxes are probably not a primary cause foranoxia-induced membrane disruption and2) glycine could prevent the plasmamembrane disruption during anoxia independently from its effect ontransmembrane electrolyte or water influxes. The present data support abiochemical rather than a mechanical alteration of the plasma membraneas the underlying cause of membrane disruption during anoxia.

     

Synthesis of RGD amphiphilic cyclic peptide as fibrinogen or fibronectin antagonist

Summary This paper investigates the effect of the incorporation of a diazaethylene glycol derivative (Deg,2) into a cyclic peptide containing the tripeptide sequence Arg-Gly-Asp (RGD). This motif is a common structural element of many integrin ligands. The synthesis of cyclo-(Arg-Gly-Asp-Deg) (7) has been accomplished in solution using standard peptide chemistry. The intent was to improve the bioavailability of this new RGD cyclic peptide, which is shown to interact with α_IIbβ₃ or α₅β₁ receptors. A preliminary step for the conformational study of peptide7 was done in DMSO-d ₆ using nuclear magnetic resonance spectroscopy techniques.     

Response of the Frog Skin to Steady-State Voltage Clamping : II. The active pathway

Active Na transport across frog skin was separated from passive Na movement utilizing urea influx as a measure of passive (shunt) permeability. In this manner, the response of the overall active Na transport system to an applied potential was determined over a range from +200 mV to -100 mV. Active Na transport displays saturation as a function of applied potential, and both the level of saturation and the potential at which it is achieved are functions of the Na concentration in the external solution. The saturation with potential appears to involve a different step in the transport process than the saturation of Na flux as a function of external Na concentration. The observations can be qualitatively described by either a one-barrier or two-barrier model of the Na transport system.     

Convenient introduction of 2-(trimethylsilyl)ethylsulfonyl (SES) amino protection on different amino acids and its use in peptidomimetic chemistry

A direct synthesis of a series of N-SES amino acids is described. N-SES Ala has been further utilized in the synthesis of a perhydro-1,4-diazepin-2-one.     

Synthesis and characterization of a new biotinylated gramicidin

A new linear gramicidin analog bearing a biotinyl group grafted on C-terminal part was designed to study ligand–receptor interactions. The C-terminal alcohol in the native peptide was first replaced by an amino group. Then the peptide was synthesized on a polystyrene resin functionalized by the 2-chlorotrityl chloride following a biotinylation performed in solution. This new N′-biotinyl-(EDA)¹⁵-Gramicidin A was reconstituted in planar lipid bilayers and exhibited channel activities similar to those of natural gramicidin, with unitary conductance value about 30 ps in 1 m KCl. Furthermore this ionophore activity was quenched by addition of streptavidin in the surrounding medium. Our system is an outstanding tool for monitoring ligand–receptor interactions and could be used for designing a new biosensor. © 1998 European Peptide Society and John Wiley & Sons, Ltd.