Mutational Analysis of the Class IIa Bacteriocin Curvacin A and Its Orientation in Target Cell Membranes

To analyze the orientation in target cell membranes of the pediocin-like bacteriocin (antimicrobial peptide) curvacin A, 55 variants were generated by site-directed mutagenesis and their potencies against four different target cells determined. The result suggest that the somewhat hydrophilic short central helix (residues 19 to 24), along with the N-terminal β-sheet-like structure (residues 1 to 16), inserts in the interface region of the target cell membrane, with Ala22 close to the hydrophobic core of the membrane. The following hinge region, with Gly28 as an important residue, may then form a turn wherein Gly28 becomes positioned near the border between the interface and the hydrophobic regions, thus permitting the longer and more-hydrophobic C-terminal helix (residues 29 to 41) to insert into the hydrophobic core of the membrane. This helix contains three glycine residues (G33, G37, and G40) that form a putative helix-helix-interacting GxxxGxxG motif. The replacement of any of these glycines with a larger residue was very detrimental, suggesting their possible involvement in helix-helix interactions with a membrane-embedded receptor protein.     

Characterization of the self-splicing products of two complex Naegleria LSU rDNA group I introns containing homing endonuclease genes.

The two group I introns Nae.L1926 and Nmo.L2563, found at two different sites in nuclear LSU rRNA genes of Naegleria amoebo-flagellates, have been characterized in vitro. Their structural organization is related to that of the mobile Physarum intron Ppo.L1925 (PpLSU3) with ORFs extending the L1-loop of a typical group IC1 ribozyme. Nae.L1926, Nmo.L2563 and Ppo.L1925 RNAs all self-splice in vitro, generating ligated exons and full-length intron circles as well as internal processed excised intron RNAs. Formation of full-length intron circles is found to be a general feature in RNA processing of ORF-containing nuclear group I introns. Both Naegleria LSU rDNA introns contain a conserved polyadenylation signal at exactly the same position in the 3' end of the ORFs close to the internal processing sites, indicating an RNA polymerase II-like expression pathway of intron proteins in vivo. The intron proteins I-NaeI and I-NmoI encoded by Nae.L1926 and Nmo.L2563, respectively, correspond to His-Cys homing endonucleases of 148 and 175 amino acids. I-NaeI contains an additional sequence motif homologous to the unusual DNA binding motif of three antiparallel beta sheets found in the I-PpoI endonuclease, the product of the Ppo.L1925 intron ORF.     

Inhibition by insulin of resistin gene expression in 3T3-L1 adipocytes.

Expression of the gene encoding resistin, a low molecular weight protein secreted from adipose tissue postulated to link obesity and type II diabetes, was examined in 3T3-L1 adipocytes. Resistin mRNA was detected in 3T3-L1 cells by day 3 following induction of differentiation into adipocytes; by day 4 the level of resistin mRNA peaked and remained high. The PPARgamma activators, rosiglitazone or darglitazone, reduced the level of resistin mRNA. Dexamethasone upregulated resistin mRNA level, but no effect was observed with the beta(3)-adrenoceptor agonist, BRL 37344. A substantial reduction in resistin mRNA level was observed with insulin, which induced decreases at physiological concentrations. Insulin may be a major inhibitor of resistin production, and this does not support a role for resistin in insulin resistance.     

The likelihood of persistent arthritis increases with the level of anti-citrullinated peptide antibody and immunoglobulin M rheumatoid factor: a longitudinal study of 376 patients with very early undifferentiated arthritis

Introduction  

We wanted to assess the importance of the levels of anti-citrullinated peptide antibody (anti-CCP) and immunoglobulin M (IgM) rheumatoid factor (RF) in predicting development of persistent arthritis from undifferentiated arthritis (UA), and to investigate whether there is an added predictive value for persistent arthritis in testing for both anti-CCP and IgM RF.     

Linking Data Choices and Context Specificity in Life Cycle Assessment of Waste Treatment Technologies: A Landfill Case Study

To generate meaningful results, life cycle assessments (LCAs) require accurate technology data that are consistent with the goal and scope of the analysis. While literature data are available for many products and processes, finding representative data for highly site‐specific technologies, such as waste treatment processes, remains a challenge. This study investigated representative life cycle inventory (LCI) modeling of waste treatment technologies in consideration of variations in technological level and climate. The objectives were to demonstrate the importance of representative LCI modeling as a function of the specificity of the study, and to illustrate the necessity of iteratively refining the goal and scope of the study as data are developed. A landfill case study was performed where 52 discrete landfill data sets were built and grouped to represent different technology options and geographical sites, potential impacts were calculated, and minimum/maximum (min‐max) intervals were generated for each group. The results showed decreasing min‐max intervals with increasing specificity of the scope of study, which indicates that compatibility between the scope of study and LCI model is critical. Hereby, this study quantitatively demonstrates the influence of representative modeling on LCA results. The results indicate that technology variations and site‐specific conditions (e.g., the influence of precipitation and cover permeability on landfill gas generation and collection) should be carefully addressed by a systematic analysis of the key process parameters. Therefore, a thorough understanding of the targeted waste treatment technologies is necessary to ensure that appropriate data choices are made within the boundaries of the defined scope of the study.     

Cholangiocytes in the pathogenesis of primary sclerosing cholangitis and development of cholangiocarcinoma

Primary sclerosing cholangitis (PSC) is an idiopathic cholangiopathy strongly associated with inflammatory bowel disease (IBD) and characterized by cholestasis, chronic immune infiltration and progressive fibrosis of the intrahepatic and extrahepatic bile ducts. PSC confers a high risk of cholangiocarcinoma (CCA) with PSC-CCA representing the leading cause of PSC-associated mortality. PSC-CCA is derived from cholangiocytes and associated progenitor cells – a heterogeneous group of dynamic epithelial cells lining the biliary tree that modulate the composition and volume of bile production by the liver. Infection, inflammation and cholestasis can trigger cholangiocyte activation leading to an increased expression of adhesion and antigen-presenting molecules as well as the release of various inflammatory and fibrogenic mediators. As a result, activated cholangiocytes engage in a myriad of cellular processes, including hepatocellular proliferation, apoptosis, angiogenesis and fibrosis. Cholangiocytes can also regulate the recruitment of immune cells, mesenchymal cells, and endothelial cells that participate in tissue repair and destruction in settings of persistent inflammation. In PSC, the role of cholangiocytes and the mechanisms governing their transformation to PSC-CCA are unclear however localization of disease suggests that cholangiocytes are a key target and potential regulator of hepatobiliary immunity, fibrogenesis and tumorigenesis. Herein, we summarize mechanisms of cholangiocyte activation in PSC and highlight new insights into disease pathways that may contribute to the development of PSC-CCA. This article is part of a Special Issue entitled: Cholangiocytes in Health and Disease edited by Jesus Banales, Marco Marzioni, Nicholas LaRusso and Peter Jansen.     

Bi-modal vertical distribution of the carnivorous copepod Paraeuchaeta norvegica

Bi-modal vertical distribution of Paraeuchaeta norvegica duringlate autumn was observed in a Norwegian fjord in three differentyears, and hence seems to be a recurring phenomenon. An uppermode performed diel vertical migration, foraging in shallowwater at night. A deep mode did not migrate vertically, butsome feeding took place at depth.     

Prevalence of skull pathologies in European harbor seals (<Emphasis Type="Italic">Phoca vitulina</Emphasis>) during 1981–2014

Harbor seals (Phoca vitulina) inhabit the seas surrounding Denmark and are an important top predator in the marine food chain. This trophic position exposes them to environmental contaminants with disease epidemics and hunting being additional threats to this population. It is therefore important to study how environmental pollution at the current order of magnitude affects the health of the population. Earlier studies have shown that occurrence of periodontitis could be linked to the amount of pollution the seals were subjected to. In order to investigate this further, 380 skulls and 141 mandibles of harbor seals (Phoca vitulina) from the Wadden Sea, the Limfjord, and Kattegat collected during the period 1970–2014 were examined. The skulls were examined for pathological lesions. The Hounsfield Units (HU) which are correlated to the bone mineral density (BMD) were measured in a subsample (n = 34) using CT scans. The macroscopic examination revealed (with the exception of the Swedish part of Kattegat) a significant increase of pathological lesions over the study period of 1981–2014. The examination of HU showed that median HU measured at multiple sites was highest in the healthy skulls compared to the skulls with one or more of the lesions. A discriminant analysis allowed high discriminatory capacity to separate healthy skulls from the skulls with pathologies, simply by the utilization of the HU data. Former studies of BMD in marine mammals have shown that exposure to environmental chemicals alter BMD and cause periodontitis. The present study, based on temporal and spatial trends in BMD, confirms the results of previous studies.