pfaB products determine the molecular species produced in bacterial polyunsaturated fatty acid biosynthesis

Insect blood (hemolymph) contains prophenoloxidase, a proenzyme that is activated to protective phenoloxidase when the insect is damaged or challenged with microorganisms. The Gram-negative bacterium Photorhabdus luminescens kills the lepidopteron insect Manduca sexta by using a variety of toxins. We screened P. luminescens and Photorhabdus asymbiotica cosmid libraries in an Escherichia coli host against previously activated M. sexta hemolymph phenoloxidase and identified three overlapping cosmid clones from P. luminescens and five from P. asymbiotica that suppressed the activity of the enzyme both in vitro and in vivo . Genome alignments of cosmid end sequences from both species confirmed that they contained orthologous loci. We examined one of the cosmids from P. luminescens in detail: it induced the formation of significantly fewer melanotic nodules, proliferated faster within the insect host and was significantly more virulent towards fifth-stage larvae than E. coli control bacteria. Insertional mutagenesis of this cosmid yielded 11 transposon mutants that were no longer inhibitory. All of these were insertions into a single 5.5-kb locus, which contained three ORFs and was homologous to the maltodextrin phosphorylase locus of E. coli . The implications of this novel inhibitory factor of insect phenoloxidase for Photorhabdus virulence are discussed.     

Docking and SAR studies of salacinol derivatives as α-glucosidase inhibitors

Salacinol is a potent α-glucosidase inhibitor isolated from Salacia reticulata, and a good lead compound for an antidiabetic drug. It is essential to clarify the binding state of salacinol to α-glucosidase for efficient optimization study using structure-based drug design. Redocking simulations of two inhibitors, acarbose and casuarine whose complex structures are known, were performed to assure the appropriate docking pose prediction. The simulation reproduced both experimental binding states with accuracy. Then, using the same simulation protocol, the binding mode of salacinol and its derivatives has been predicted. Salacinol bound to the protein with a similar binding mode as casuarine, and the predicted structures could explain most of the structure–activity relationships of salacinol derivatives.     

Comparison of Vegetation and CO2 Dynamics Between a Restored Cut‐Away Peatland and a Pristine Fen: Evaluation of the Restoration Success

We studied the restoration success of a cut‐away peatland 10 years after restoration by comparing the vegetation and CO₂ dynamics with those of a pristine peatland of similar nutrition level and climate. Vegetation and CO₂ dynamics were monitored during one growing season. We used DCA (detrended correspondence analysis) and diversity indices to study the vegetation composition within and between the sites, and non‐linear regression models to estimate the seasonal CO₂ fluxes and balances of the sites. Based on both DCA and diversity indices, the study plots in the restored site differed more in the vegetation composition than the study plots in the pristine site. The variation in the CO₂ fluxes and balance was greater in the restored than in the pristine site, resulting from the heterogeneous vegetation in the restored site. The seasonal net CO₂ balance was positive (sink) at both sites, the restored site binding on average 500 ± 410 g CO₂/m² and the pristine site 390 ± 265 g CO₂/m² (statistically not different, p = 0.575). The results indicate that the restoration of the vegetation composition is still incomplete but the vegetation coverage is sufficient for the restored site to function as a sink of atmospheric CO₂.     

Up to seven-fold inter-hospital differences in obstetric anal sphincter injury rates- A birth register-based study in Finland

Background

The occurrence of obstetric anal sphincter injuries (OASIS) - which may have serious, long-term effects on affected women, including faecal incontinence, despite primary repair - varies widely between countries and have been chosen one of the indicators for patient safety in Organisation for Economic Cooperation and Development (OECD) countries and in Nordic countries.

Findings

The aim of the study was to assess risks of OASIS among five university teaching hospitals and 14 non-university central hospitals with more than 1,000 deliveries annually during 1997-2007 in Finland. Women with singleton vaginal deliveries divided into two populations consisting of all 168,637 women from five university hospitals and all 255,660 women from non-university hospitals, respectively, derived from population-based register. Primiparous and multiparous women with OASIS (n = 2,448) were compared in terms of possible risk factors to primiparous and multiparous women without OASIS, respectively, using stepwise logistic regression analysis. The occurrences of OASIS varied from 0.7% to 2.1% in primiparous and from 0.1% to 0.3% in multiparous women among the university hospitals. Three-fold inter-hospital differences in OASIS rates did not significantly change after adjustment for patient mix or the use of interventions. In non-university hospitals OASIS rates varied from 0.2% to 1.4% in primiparous and from 0.02% to 0.4% in multiparous women, and the results remained virtually unchanged after adjustment for known risks.

Conclusions

Up to 3.2-fold inter-hospital differences in OASIS risk demonstrates significant differences in the quality of Finnish obstetric care.

     

An objective classification system of air mass types for Szeged, Hungary, with special attention to plant pollen levels

This paper discusses the characteristic air mass types over the Carpathian Basin in relation to plant pollen levels over annual pollination periods. Based on the European Centre for Medium-Range Weather Forecasts dataset, daily sea-level pressure fields analysed at 00 UTC were prepared for each air mass type (cluster) in order to relate sea-level pressure patterns to pollen levels in Szeged, Hungary. The database comprises daily values of 12 meteorological parameters and daily pollen concentrations of 24 species for their pollination periods from 1997 to 2001. Characteristic air mass types were objectively defined via factor analysis and cluster analysis. According to the results, nine air mass types (clusters) were detected for pollination periods of the year corresponding to pollen levels that appear with higher concentration when irradiance is moderate while wind speed is moderate or high. This is the case when an anticyclone prevails in the region west of the Carpathian Basin and when Hungary is under the influence of zonal currents (wind speed is high). The sea level pressure systems associated with low pollen concentrations are mostly similar to those connected to higher pollen concentrations, and arise when wind speed is low or moderate. Low pollen levels occur when an anticyclone prevails in the region west of the Carpathian Basin, as well as when an anticyclone covers the region with Hungary at its centre. Hence, anticyclonic or anticyclonic ridge weather situations seem to be relevant in classifying pollen levels.     

IL-17A promotes the growth of airway epithelial cells through ERK-dependent signaling pathway

The effects of IL-17A on mucin production and growth of airway epithelial cells were examined. Histological and immunohistochemical analyses revealed that IL-17A increased the mucin production and number of tracheal epithelial cells in air-liquid interface cultures. The biological property of IL-17A to stimulate the mucin production by tracheal epithelial cells was determined using an ELISA. The mitogenic effect of IL-17A on tracheal epithelial cells was confirmed with Calcein-AM assay. The growth-stimulatory effect of IL-17A was dose-dependent and mediated via the ERK MAP kinase pathway. Inhibitors of MEK abrogated the mitogenic effect of IL-17A, whereas an inhibitor of p38 or JNK displayed no significant inhibitory effect. Moreover, relatively lower doses of IL-13 also significantly increased the growth of tracheal epithelial cells through a distinct signaling pathway from that of IL-17A. These findings provide the first evidence that IL-17A stimulates the growth of airway epithelial cells through the ERK MAP kinase pathway.     

The selective continued linkage of centromeres from mitosis to interphase in the absence of mammalian separase

Separase is an evolutionarily conserved protease that is essential for chromosome segregation and cleaves cohesin Scc1/Rad21, which joins the sister chromatids together. Although mammalian separase also functions in chromosome segregation, our understanding of this process in mammals is still incomplete. We generated separase knockout mice, reporting an essential function for mammalian separase. Separase-deficient mouse embryonic fibroblasts exhibited severely restrained increases in cell number, polyploid chromosomes, and amplified centrosomes. Chromosome spreads demonstrated that multiple chromosomes connected to a centromeric region. Live observation demonstrated that the chromosomes of separase-deficient cells condensed, but failed to segregate, although subsequent cytokinesis and chromosome decondensation proceeded normally. These results establish that mammalian separase is essential for the separation of centromeres, but not of the arm regions of chromosomes. Other cell cycle events, such as mitotic exit, DNA replication, and centrosome duplication appear to occur normally. We also demonstrated that heterozygous separase-deficient cells exhibited severely restrained increases in cell number with apparently normal mitosis in the absence of securin, which is an inhibitory partner of separase.     

6-Amino-6-deoxy-chitosan. Sequential chemical modifications at the C-6 positions of N-phthaloyl-chitosan and evaluation as a gene carrier

The C-6 positions of chitosan were successively modified in a highly regioselective manner. The starting material, N-phthaloyl-chitosan, was successfully converted into the corresponding 6-deoxy-6-halo derivatives by reaction with N-halosuccinimides and triphenylphosphine in N-methyl-2-pyrrolidone. The resulting chloride and bromide derivatives were then substituted with azido groups by reaction with sodium azide at 120 and 80 degrees C, respectively. The azido groups were then reduced to amines via formation of the triphenylphosphinimine intermediate followed by hydrolysis using aqueous hydrazine, which also led to the removal of the N-phthaloyl groups at the C-2 positions. This sequence gave 6-amino-6-deoxy-chitosan, which, unlike chitosan, is soluble in water at neutral pH. The synthesized 6-amino-6-deoxy-chitosan derivative was evaluated as a gene carrier, and the transfection efficiency for COS-1 cells was shown to be superior to chitosan. In addition, the cytotoxicity was similar to chitosan.     

PAR3 is essential for cyst-mediated epicardial development by establishing apical cortical domains

Epithelial cysts are one of the fundamental architectures for mammalian organogenesis. Although in vitro studies using cultured epithelial cells have revealed proteins required for cyst formation, the mechanisms that orchestrate the functions of these proteins in vivo remain to be clarified. We show that the targeted disruption of the mouse Par3 gene results in midgestational embryonic lethality with defective epicardial development. The epicardium is mainly derived from epicardial cysts and essential for cardiomyocyte proliferation during cardiac morphogenesis. PAR3-deficient epicardial progenitor (EPP) cells do not form cell cysts and show defects in the establishment of apical cortical domains, but not in basolateral domains. In PAR3-deficient EPP cells, the localizations of aPKC, PAR6beta and ezrin to the apical cortical domains are disturbed. By contrast, ZO1 and alpha4/beta1 integrins normally localize to cell-cell junctions and basal domains, respectively. Our observations indicate that EPP cell cyst formation requires PAR3 to interpret the polarity cues from cell-cell and cell-extracellular matrix interactions so that each EPP cell establishes apical cortical domains. These results also provide a clear example of the proper organization of epithelial tissues through the regulation of individual cell polarity.     

Inhibition of MHC class II expression and immune responses by c-MIR

We previously reported a novel E3 ubiquitin ligase (E3), designated as c-MIR, which targets B7-2 to lysosomal degradation and down-regulates the B7-2 surface expression through ubiquitination of its cytoplasmic tail. B7-2 is well known as a costimulatory molecule for Ag presentation, suggesting that the manipulation of c-MIR expression modulates immune responses in vivo. To examine this hypothesis, we generated genetically modified mice in which c-MIR was expressed under an invariant chain (Ii) promoter. Dendritic cells derived from genetically engineered mice showed low ability to present Ags. In addition, these mice showed resistance to the onset of experimental autoimmune encephalomyelitis and an impaired development of CD4 T cells in the thymus and the periphery. These findings led us to conclude that MHC class II (MHC II) is an additional target for c-MIR. Indeed, forced expression of c-MIR in several B cell lines down-regulated the surface expression of MHC II, and down-regulation was found to depend on the presence of a single lysine residue in the cytoplasmic tail of the I-A beta-chain. In a reconstitution system using 293T cells, we found that the lysine residue at position 225 in the I-A beta-chain was ubiquitinated by c-MIR. To our knowledge, c-MIR is the first example of an E3 that is capable of inhibiting MHC II expression. Our findings suggest that c-MIR might potently regulate immune responses in vivo.