Non-motile mutants of Helicobacter pylori and Helicobacter mustelae defective in flagellar hook production

Flagellar hooks were purified from Helicobacter pylori and Helicobacter mustelae. The 70 × 16nm H. pylori hook was composed of FIgE subunits of 78kDa, while the 72 × 16nm H. mustelae hook was composed of 87kDa subunits. N-terminal sequence was obtained for the FIgH proteins of both species, and for an internal H. mustelae FlgE peptide. Degenerate oligonucleotide primers allowed amplification of a 1.2 kb fragment from the H. mustelae chromosome, which carried part of the flgE gene. The corresponding H. pylori gene was cloned by immunoscreening of a genomic library constructed in λZAP Express, The translated H. pylori flgE sequence indicated a protein with limited homology with the hook proteins from Salmonella typhimurium and Treponema phagedenis. Mutants of H. pylori and H. mustelae defective in hook production generated by allele replacement were non-motile and devoid of flagellar filaments but produced both flagellin subunits, which were localized in the soluble fraction of the cell. The level of flagellin production was unchanged in the mutants, indicating that the regulation of flagellin expression in Helicobacter differs from that in the Enterobacteriaceae.     

Different UmuC requirements for generation of different kinds of UV-induced mutations in Escherichia coli

An Escherichia coli strain bearing the dnaQ49 mutation, which results in a defective s subunit of DNA polymerase III, and carrying the lexA71 mutation, which causes derepression of the SOS regulon, is totally unable to maintain high-copy-number plasmids containing the umuDC operon. The strain is also unable to maintain the pAN4 plasmid containing a partial deletion of the umuD gene but retaining the wild-type umuC gene. These results suggest that a high cellular level of UmuC is exceptionally harmful to the defective DNA polymerase III of the dnaQ49 mutant. We have used this finding as a basis for selection of new plasmid umuC mutants. The properties of two such mutants, bearing the umuC61 or umuC95 mutation, are described in detail. In the umuC122:: Tn 5 strain harbouring the mutant plasmids, UV-induced mutagenesis is severely decreased compared to that observed with the parental umuDC ⁺ plasmid. Interestingly, while the frequency of UV-induced GC → AT transitions is greatly reduced, the frequency of AT → TA transversions is not affected. Both mutant plasmids bear frameshift mutations within the same run of seven A residues present in umuC ⁺; in umuC61 the run is shortened to six A whereas in umuC95 is lengthened to eight A. We have found in both umuC61 and umuC95 that translation is partially restored to the proper reading frame. We propose that under conditions of limiting amounts of UmuC, the protein preferentially facilitates processing of only some kinds of UV-induced lesions.     

Improvement of somatic embryogenesis inFeijoa sellowiana berg (Myrtaceae) by manipulation of culture media composition

Summary Somatic embryos could be induced from the cotyledons of zygotic embryos from immature fruits ofFeijoa sellowiana Berg (Feijoa) in the presence of a wide range of concentrations of fructose, glucose, maltose, and sucrose. Mannitol or sorbitol alone were ineffective. The highest frequencies of induction (99%) and the greatest number of somatic embryos per explant (134) were obtained with 0.4M fructose and 0.3M sucrose, respectively. This sucrose concentration also showed greater induction capacity than equimolar combinations of its monosaccharide constituents combined. Somatic embryo development was arrested at the globular stage at concentrations higher than 0.5M of all the sugars tested. When transferred to solid germination medium containing 2.0 mg/liter (5.77μM) gibberellic acid, 0.5 mg/liter (2.32μM) kinetin, and 0.029M sucrose, somatic embryos formed under 0.3 or 0.4M sucrose had better germination capacity than those induced under lower (0.1 and 0.2M) concentrations, as assessed by the frequency of explants presenting germinated embryos and by the number of plants obtained from those explants. On liquid media of similar composition somatic embryos did not germinate. Our data suggest that high (0.3 to 0.4M) carbohydrate levels improve somatic embryogenesis by acting both as carbon source and as osmotic regulator.     

Combining industrial ecology tools to assess potential greenhouse gas reductions of a circular economy: Method development and application to Switzerland

Industrial ecology (IE) methodologies, such as input/output or material flow analysis and life cycle assessment (LCA), are often used for the environmental evaluation of circular economy strategies. Up to now, an approach that utilizes these methods in a systematic, integrated framework for a holistic assessment of a geographic region's sustainable circular economy potential has been lacking. The approach developed in this study (IE4CE approach) combines IE methodologies to determine the environmental impact mitigation potential of circular economy strategies for a defined geographic region. The approach foresees five steps. First, input/output analysis helps identify sectors with high environmental impacts. Second, a refined analysis is conducted using material flow and LCA. In step 3, circular strategies are used for scenario design and evaluated in step 4. In step 5, the assessment results are compiled and compared across sectors. The approach was applied to a case study of Switzerland, analyzing 8 sectors and more than 30 scenarios in depth. Carbon capture and storage (CCS) from waste incineration, biogas and cement production, food waste prevention in households, hospitality and production, and the increased recycling of plastics had the highest mitigation potential. Most of the scenarios do not influence each other. One exception is the CCS scenarios: waste avoidance scenarios decrease the reduction potential of CCS. A combination of scenarios from different sectors, including their impact on the CCS scenario potential, led to an environmental impact mitigation potential of 11.9 Mt CO₂-eq for 2050, which equals 14% of Switzerland's current consumption-based impacts.     

Identification of a UDP-glucosyltransferase conferring deoxynivalenol resistance in Aegilops tauschii and wheat

Aegilops tauschii is the diploid progenitor of the wheat D subgenome and a valuable resource for wheat breeding, yet, genetic analysis of resistance against Fusarium head blight (FHB) and the major Fusarium mycotoxin deoxynivalenol (DON) is lacking. We treated a panel of 147 Ae. tauschii accessions with either Fusarium graminearum spores or DON solution and recorded the associated disease spread or toxin-induced bleaching. A k-mer-based association mapping pipeline dissected the genetic basis of resistance and identified candidate genes. After DON infiltration nine accessions revealed severe bleaching symptoms concomitant with lower conversion rates of DON into the non-toxic DON-3-O-glucoside. We identified the gene AET5Gv20385300 on chromosome 5D encoding a uridine diphosphate (UDP)-glucosyltransferase (UGT) as the causal variant and the mutant allele resulting in a truncated protein was only found in the nine susceptible accessions. This UGT is also polymorphic in hexaploid wheat and when expressed in Saccharomyces cerevisiae only the full-length gene conferred resistance against DON. Analysing the D subgenome helped to elucidate the genetic control of FHB resistance and identified a UGT involved in DON detoxification in Ae. tauschii and hexaploid wheat. This resistance mechanism is highly conserved since the UGT is orthologous to the barley UGT HvUGT13248 indicating descent from a common ancestor of wheat and barley.     

Circannual Variations in Blood Cholesterol Levels

The seasonality of blood cholesterol is still not well established. Some have described a seasonal pattern with highest levels during autumn and lowest in summer, whereas others have reported no change. A number of studies showed circannual variations with maximum levels in winter and minimum in summer. The aim of this study was to examine the circannual variation of cholesterol in a large cohort in Israel. In the Israeli CORDIS study, employees of 21 factories were screened for cardiovascular disease risk factors during 1985-7. As part of the information gathered, serum cholesterol and blood counts were available for 3,726 men and 1,514 women. Serum cholesterol levels fit a circannual rhythm assessed by the cosinor analysis. Highest levels of serum cholesterol were found in spring and lowest in summer. We conclude that there is a circannual change of serum cholesterol, which could be partially associated with changes in environmental temperature. The circannual variation in serum cholesterol was considerable and should be taken into account when carrying out clinical evaluation of patients.     

Effect of dietary caffeine and zinc on the activity of antioxidant enzymes,zinc, and copper concentration of the heart and liver in fast-growing rats

The purpose of this study was to determine the relationship between concentrations of Zn and Cu and the activities of superoxide dismutase and glutathione peroxidase in the heart and liver of young rat pups whose dams were fed a diet supplemented with caffeine and/or Zn. Four groups of dams with their newborn pups were fed one of the following diets for 22 d: 20% protein basal diet; the basal diet supplemented with caffeine (2 mg/100 body wt); the basal diet supplemented with Zn (300 mg/kg diet); or the basal diet supplemented with caffeine plus Zn. The Cu levels in the livers of the pups were decreased by maternal intake of the caffeine and Zn diet. The maternal intake of the caffeine diet increased Mn-superoxide dismutase (MnSOD) activity and Cu, Zn-superoxide dismutase (CUZnSOD) in the heart of the pups. On the other hand, the activity of Cu,ZnSOD was significantly reduced in the liver of pups whose dams consumed a caffeine, Zn, or caffeine plus Zn diet. Cu, ZnSOD activity in the liver of the pups seems to be correlated with Cu levels in the tissue. Selenium-dependent glutathione peroxidase (GSH-Px) activities in the heart and liver showed no difference among the groups. The effect of dietary caffeine and/or Zn on the activity of antioxidant enzymes in the heart and liver were different in young rats. The activities of these enzymes in the heart were lower than in the liver of 22-d-old rats. Our experiments indicate that the heart has limited defenses against the toxic effects of peroxides when compared to the liver.