ProNGF induces p75-mediated death of oligodendrocytes following spinal cord injury

The neurotrophin receptor p75 is induced by various injuries to the nervous system, but its role after injury has remained unclear. Here, we report that p75 is required for the death of oligodendrocytes following spinal cord injury, and its action is mediated mainly by proNGF. Oligodendrocytes undergoing apoptosis expressed p75, and the absence of p75 resulted in a decrease in the number of apoptotic oligodendrocytes and increased survival of oligodendrocytes. ProNGF is likely responsible for activating p75 in vivo, since the proNGF from the injured spinal cord induced apoptosis among p75(+/+), but not among p75(-/-), oligodendrocytes in culture, and its action was blocked by proNGF-specific antibody. Together, these data suggest that the role of proNGF is to eliminate damaged cells by activating the apoptotic machinery of p75 after injury.     

Formin-2, polyploidy,hypofertility and positioning of the meiotic spindle in mouse oocytes

Successful reproduction in mammals requires a competent egg, which is formed during meiosis through two assymetrical cell divisions. Here, we show that a recently identified formin homology (FH) gene, formin-2 (Fmn2), is a maternal-effect gene that is expressed in oocytes and is required for progression through metaphase of meiosis I. Fmn2(-/-) oocytes cannot correctly position the metaphase spindle during meiosis I and form the first polar body. We demonstrate that Fmn2 is required for microtubule-independent chromatin positioning during metaphase I. Fertilization of Fmn2(-/-) oocytes results in polyploid embryo formation, recurrent pregnancy loss and sub-fertility in Fmn2(-/-) females. Injection of Fmn2 mRNA into Fmn2-deficient oocytes rescues the metaphase I block. Given that errors in meiotic maturation result in severe birth defects and are the most common cause of chromosomal aneuploidy and pregnancy loss in humans, studies of Fmn2 may provide a better understanding of infertility and birth defects.     

Successful immunotherapy with matrix metalloproteinase-derived peptides in adjuvant arthritis depends on the timing of peptide administration

We have recently found that matrix metalloproteinases (MMPs) are targets for T-cell and B-cell reactivity in experimental arthritis. In the present article, we investigate whether modulation of MMP-specific T-cell responses could influence the course of adjuvant arthritis (AA). Lewis rats were treated nasally with MMP peptides prior to or after AA induction. Administration of the MMP-10 or the MMP-16 peptide prior to AA induction reduced the arthritic symptoms. In contrast, administration of the MMP-10 peptide after AA induction aggravated the arthritic symptoms. The present study shows the possible usefulness of MMP peptides for immunotherapy. However, a clear understanding of proper timing of peptide administration is crucial for the development of such therapies.     

Cysteine residues in the nucleotide binding domains regulate the conductance state of CFTR channels

Gating of cystic fibrosis transmembrane conductance regulator (CFTR) channels requires intermolecular or interdomain interactions, but the exact nature and physiological significance of those interactions remains uncertain. Subconductance states of the channel may result from alterations in interactions among domains, and studying mutant channels enriched for a single conductance type may elucidate those interactions. Analysis of CFTR channels in inside-out patches revealed that mutation of cysteine residues in NBD1 and NBD2 affects the frequency of channel opening to the full-size versus a 3-pS subconductance. Mutating cysteines in NBD1 resulted in channels that open almost exclusively to the 3-pS subconductance, while mutations of cysteines in NBD2 decreased the frequency of subconductance openings. Wild-type channels open to both size conductances and make fast transitions between them within a single open burst. Full-size and subconductance openings of both mutant and wild-type channels are similarly activated by ATP and phosphorylation. However, the different size conductances open very differently in the presence of a nonhydrolyzable ATP analog, with subconductance openings significantly shortened by ATPgammaS, while full-size channels are locked open. In wild-type channels, reducing conditions increase the frequency and decrease the open time of subconductance channels, while oxidizing conditions decrease the frequency of subconductance openings. In contrast, in the cysteine mutants studied, altering redox potential has little effect on gating of the subconductance.     

Differentiation of Arcobacter species by numerical analysis of AFLP profiles and description of a novel Arcobacter from pig abortions and turkey faeces

AIMS: To evaluate the efficacy of amplified fragment length polymorphism (AFLP)-based genetic profiling for taxonomic and epidemiological analyses of diverse Arcobacter species. METHODS AND RESULTS: Seventy-two isolates of A. butzleri, A. cryaerophilus, A. skirrowii and A. nitrofigilis, and a previously unclassified porcine abortion strain were studied. AFLP profiling was performed using a BglII-Csp6I-based protocol previously used to characterize Campylobacter species. Duplicate profiles of 20 isolates were 93.25% similar, indicating high reproducibility. Numerical analysis of all 72 strains revealed five phenons at the 29% similarity level, four of which represented each of the known species studied. The remaining phenon was further characterized by phenotypic and 16S rDNA sequence analyses, the results of which indicated it to be a novel Arcobacter species. The genetically distinct subgroups of A. cryaerophilus were differentiated at the 39.5% similarity level. For strain typing, 62 distinct types were defined, with evidence of clonal lineages within A. butzleri, A. cryaerophilus and A. skirrowii. CONCLUSIONS: AFLP profiling is an effective means of determining taxonomic and strain relationships for arcobacters. SIGNIFICANCE AND IMPACT OF THE STUDY: First use of AFLP profiling for diverse Arcobacter species; indication of clonality in A. butzleri, A. cryaerophilus and A. skirrowii; potentially novel Arcobacter taxon identified.     

Avian reservoirs and zoonotic potential of the emerging human pathogen Helicobacter canadensis

A polyphasic identification approach was used to investigate the taxonomic position of Campylobacter-like isolates recovered from barnacle geese (Branta leucopsis) and Canada geese (Branta candensis). Seven strains were selected from a collection of 21 isolates and analyzed by extensive phenotypic testing; four strains were characterized by 16S rRNA gene sequence analysis. The results clearly identified the bird isolates as Helicobacter canadensis, recently described as an emerging human pathogen. This is the first report of an animal reservoir for this organism and of its presence in Europe and confirms the zoonotic potential of H. canadensis.     

Visualisation and graph-theoretic analysis of a large-scale protein structural interactome

Background  

Large-scale protein interaction maps provide a new, global perspective with which to analyse protein function. PSIMAP, the Protein Structural Interactome Map, is a database of all the structurally observed interactions between superfamilies of protein domains with known three-dimensional structure in the PDB. PSIMAP incorporates both functional and evolutionary information into a single network.