Identification of small peptides mimicking the R2 C-terminus of Mycobacterium tuberculosis ribonucleotide reductase.

Ribonucleotide reductase (RNR) is a viable target for new drugs against the causative agent of tuberculosis, Mycobacterium tuberculosis. Previous work has shown that an N-acetylated heptapeptide based on the C-terminal sequence of the smaller RNR subunit can disrupt the formation of the holoenzyme sufficiently to inhibit its function. Here the synthesis and binding affinity, evaluated by competitive fluorescence polarization, of several truncated and N-protected peptides are described.

Burrow air phase maintenance and respiration by the mudskipper Scartelaos histophorus (Gobiidae: Oxudercinae).

A laboratory burrow and mudflat system was used to examine aspects of burrow air-phase maintenance and utilization by the amphibious mudskipper Scartelaos histophorus. While confined to its burrow during simulated 'high tide', this species respires both aquatically and aerially, in the latter case utilizing an air phase it had established by transporting air into the burrow during simulated 'low tide'. Over the course of 'high-tide' confinement, burrow-water P(O2) declines, making the air phase more important for respiration; the burrow-water O2 tension eliciting air-phase respiration is 4.

The alternatively spliced alpha(E)C domain of human fibrinogen-420 is a novel ligand for leukocyte integrins alpha(M)beta(2) and alpha(X)beta(2).

The interaction of human plasma fibrinogen with leukocyte integrins alpha(M)beta(2) (CD11b/CD18, Mac-1) and alpha(X)beta(2) (CD11c/CD18, p150,95) is an important component of the inflammatory response. Previously, it was demonstrated that binding of fibrinogen to these integrins is mediated by gammaC, the globular C-terminal domain of the gamma chain. In this study, evidence was found of another fibrinogen domain that can serve as a ligand for the 2 leukocyte integrins: alpha(E)C, a homologous domain that extends the alpha chains in a recently discovered subclass of fibrinogen known as fibrinogen-420.

The effects of spatial habitat configuration on recruitment, growth and population structure in arctic Collembola.

The population density and demography of five species of arctic Collembola were studied in a naturally patchy habitat, consisting of Carex ursinae tussocks with varying degrees of isolation. Focal predictor variables were those describing the spatial configuration of tussocks, including tussock size and isolation and the amount of habitat (cover) at a 1-m scale surrounding each tussock population. The Collembola populations were heavily influenced by environmental stochasticity in the form of winter mortality and summer drought, and the influence of patchiness on population characteristics was evaluated in this context.

The alpha(E)C domain of human fibrinogen-420 is a stable and early plasmin cleavage product.

Human fibrinogen-420, (alpha(E)betagamma)(2), was isolated from plasma and evaluated for its ability to form clots and for its susceptibility to proteolysis. Clotting parameters, including cross-linking of subunit chains, of this subclass and of the more abundant fibrinogen-340 (alphabetagamma)(2), were found to be similar, suggesting little impact of the unique alpha(E)C domains of fibrinogen-420 on coagulation. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis of plasmic digestion patterns revealed production from fibrinogen-420 of the conventional fibrinogen degradation products, X, Y, D, and E, to be comparable to that from fibrinogen-340 in all respects except the presence of at least 2 additional cleavage products that were shown by Western blot analysis to contain the alpha(E)C domain.