Structure and regulation of the Erwinia carotovora subspecies carotovora SCC3193 cellulase gene celV1 and the role of cellulase in phytopathogenicity

The ceIV1 gene encoding a secreted cellulase (CelV1) of Erwinia carotovora subsp. carotovora SCC3193 was cloned and its nucleotide sequence determined. The gene contains an open reading frame of 1511 by and codes for an exported protein of 504 amino acids. The predicted amino acid sequence of Ce1V1 was highly similar to that of CeIV of another E. c. subsp. carotovora strain SCRI193 but completely different from the previously characterized cellulase, CelS, of the strain SCC3193. Gene fusions to the lacZ reporter were employed to characterize the regulation of celV1 and celS. Both genes are coordinately induced in a growth phase-dependent manner and are catabolite repressed. Expression of celV1 but not celS was stimulated by plant extracts. The celS gene was expressed at a much lower level than celV1 under all conditions tested. Inactivation of the celV1 gene in E. c. subsp. carotovora strain SCC3193 by marker exchange showed that celV1 encodes the major cellulase of strain SCC3193, as the resulting mutant strain SCC6001 was devoid of cellulase activity. Ce1Vl mutants exhibited reduced virulence suggesting that CelV1, although not absolutely required for pathogenicity, enhances the ability of strain SCC3193 to macerate plant tissue. Inactivation of the celS gene in the celV1 mutant did not lead to any further decrease in virulence.     

Climate change‐induced vegetation change as a driver of increased subarctic biogenic volatile organic compound emissions

Emissions of biogenic volatile organic compounds (BVOCs) have been earlier shown to be highly temperature sensitive in subarctic ecosystems. As these ecosystems experience rapidly advancing pronounced climate warming, we aimed to investigate how warming affects the BVOC emissions in the long term (up to 13 treatment years). We also aimed to assess whether the increased litterfall resulting from the vegetation changes in the warming subarctic would affect the emissions. The study was conducted in a field experiment with factorial open‐top chamber warming and annual litter addition treatments on subarctic heath in Abisko, northern Sweden. After 11 and 13 treatment years, BVOCs were sampled from plant communities in the experimental plots using a push–pull enclosure technique and collection into adsorbent cartridges during the growing season and analyzed with gas chromatography–mass spectrometry. Plant species coverage in the plots was analyzed by the point intercept method. Warming by 2 °C caused a 2‐fold increase in monoterpene and 5‐fold increase in sesquiterpene emissions, averaged over all measurements. When the momentary effect of temperature was diminished by standardization of emissions to a fixed temperature, warming still had a significant effect suggesting that emissions were also indirectly increased. This indirect increase appeared to result from increased plant coverage and changes in vegetation composition. The litter addition treatment also caused significant increases in the emission rates of some BVOC groups, especially when combined with warming. The combined treatment had both the largest vegetation changes and the highest BVOC emissions. The increased emissions under litter addition were probably a result of a changed vegetation composition due to alleviated nutrient limitation and stimulated microbial production of BVOCs. We suggest that the changes in the subarctic vegetation composition induced by climate warming will be the major factor indirectly affecting the BVOC emission potentials and composition.     

Isolation and Identification of Aspergillus fumigatus Mycotoxins on Growth Medium and Some Building Materials

Genotoxic and cytotoxic compounds were isolated and purified from the culture medium of an indoor air mold, Aspergillus fumigatus. One of these compounds was identified as gliotoxin, a known fungal secondary metabolite. Growth of A. fumigatus and gliotoxin production on some building materials were also studied. Strong growth of the mold and the presence of gliotoxin were detected on spruce wood, gypsum board, and chipboard under saturation conditions.     

A new species in the Mycosphaerellaceae from Cecidomyiidae leaf galls on Avicennia marina in South Africa

Antonie van Leeuwenhoek - During studies to investigate the health of mangrove trees in South Africa, high numbers of Avicennia marina were found with leaf galls caused by unidentified adults and...     

Discovery of exposure markers in urine for Brassica-containing meals served with different protein sources by UPLC-qTOF-MS untargeted metabolomics

An untargeted metabolomics approach has been applied to discover and identify exposure markers in urine for nine Nordic meals. A cross-over meal study was carried out in 17 subjects. The meals included a Pie, a Soup and a Barleyotto (pearl barley based risotto), each prepared with three protein sources; meat, fish or vegetarian. Urine samples were collected in different time intervals before and after intake of the test meals, covering a total of 24 h. The samples were analyzed by UPLC-qTOF-MS. Discriminating features for meals and protein sources were selected by use of double cross-validated partial least squares discriminant analysis and two additional validation steps: (1) time-course of excretion and (2) analysis of sensitivity and specificity. In addition, eight meal studies with single foods were carried out to investigate the food sources of the markers. In total 31 potential exposure markers (PEMs) of foods were found for the meals and protein sources. Fifteen of the 31 PEMs were also found in studies with single foods. Ten PEMs were identified or putatively annotated. Among the PEMs were a range of conjugated isothiocyanates from the Brassica oleracea species. Trimethylamine N-oxide was found as a fish marker. Additional unknown PEMs were found for chicory salad, parsley and fava beans, while other PEMs were dependent on the meal matrix rather than individual foods. The study demonstrates that it is possible to find PEMs in 24 h urine samples even when foods are given as part of a complex meal.     

A global review and meta-analysis of applications of the freshwater Fish Invasiveness Screening Kit

Reviews in Fish Biology and Fisheries - The freshwater Fish Invasiveness Screening Kit (FISK) has been applied in 35 risk assessment areas in 45 countries across the six inhabited continents (11...     

A single bout of exercise with high mechanical loading induces the expression of Cyr61/CCN1 and CTGF/CCN2 in human skeletal muscle.

High mechanical loading was hypothesized to induce the expression of angiogenic and/or lymphangiogenic extracellular matrix (ECM) proteins in skeletal muscle. Eight men performed a strenuous exercise protocol, which consisted of 100 unilateral maximal drop jumps followed by submaximal jumping until exhaustion. Muscle biopsies were taken 30 min and 48 h postexercise from the vastus lateralis muscle and analyzed for the following parameters: mRNA and protein expression of ECM-associated CCN proteins [cysteine-rich angiogenic protein 61 (Cyr61)/CCN1, connective tissue growth factor (CTGF)/CCN2], and mRNA expression of vascular endothelial growth factors (VEGFs) and hypoxia-inducible factor-1alpha. The mRNA expression of Cyr61 and CTGF increased 30 min after the exercise (14- and 2.5-fold, respectively; P < 0.001). Cyr61 remained elevated 48 h postexercise (threefold; P < 0.05). The mRNA levels of VEGF-A, VEGF-B, VEGF-C, VEGF-D, or hypoxia-inducible factor-1alpha did not change significantly at either 30 min or 48 h postexercise; however, the variation between subjects increased markedly in VEGF-A and VEGF-B mRNA. Cyr61 protein levels were higher at both 30 min and 48 h after the exercise compared with the control (P < 0.05). Cyr61 and CTGF proteins were localized to muscle fibers and the surrounding ECM by immunohistochemistry. Fast fibers stained more intensively than slow fibers. In conclusion, mechanical loading induces rapid expression of CCN proteins in human skeletal muscle. This may be one of the early mechanisms involved in skeletal muscle remodeling after exercise, since Cyr61 and CTGF regulate the expression of genes involved in angiogenesis and ECM remodeling.     

Income differences in COVID-19 incidence and severity in Finland among people with foreign and native background: A population-based cohort study of individuals nested within households

BackgroundAlthough intrahousehold transmission is a key source of Coronavirus Disease 2019 (COVID-19) infections, studies to date have not analysed socioeconomic risk factors on the household level or household clustering of severe COVID-19. We quantify household income differences and household clustering of COVID-19 incidence and severity.Methods and findingsWe used register-based cohort data with individual-level linkage across various administrative registers for the total Finnish population living in working-age private households (N = 4,315,342). Incident COVID-19 cases (N = 38,467) were identified from the National Infectious Diseases Register from 1 July 2020 to 22 February 2021. Severe cases (N = 625) were defined as having at least 3 consecutive days of inpatient care with a COVID-19 diagnosis and identified from the Care Register for Health Care between 1 July 2020 and 31 December 2020. We used 2-level logistic regression with individuals nested within households to estimate COVID-19 incidence and case severity among those infected.Adjusted for age, sex, and regional characteristics, the incidence of COVID-19 was higher (odds ratio [OR] 1.67, 95% CI 1.58 to 1.77, p < 0.001, 28.4% of infections) among individuals in the lowest household income quintile than among those in the highest quintile (18.9%). The difference attenuated (OR 1.23, 1.16 to 1.30, p < 0.001) when controlling for foreign background but not when controlling for other household-level risk factors. In fact, we found a clear income gradient in incidence only among people with foreign background but none among those with native background. The odds of severe illness among those infected were also higher in the lowest income quintile (OR 1.97, 1.52 to 2.56, p < 0.001, 28.0% versus 21.6% in the highest quintile), but this difference was fully attenuated (OR 1.08, 0.77 to 1.52, p = 0.64) when controlling for other individual-level risk factors—comorbidities, occupational status, and foreign background. Both incidence and severity were strongly clustered within households: Around 77% of the variation in incidence and 20% in severity were attributable to differences between households. The main limitation of our study was that the test uptake for COVID-19 may have differed between population subgroups.ConclusionsLow household income appears to be a strong risk factor for both COVID-19 incidence and case severity, but the income differences are largely driven by having foreign background. The strong household clustering of incidence and severity highlights the importance of household context in the prevention and mitigation of COVID-19 outcomes.

Sanni Saarinen and colleagues explore the association between income differences and COVID-19 incidence and severity among people with foreign and native background in Finland.     

Relations of APOE promoter polymorphisms to LDL cholesterol and markers of subclinical atherosclerosis in young adults

The common apolipoprotein E (apoE) gene (APOE) epsilon2/epsilon3/epsilon4 polymorphism explains part of serum lipid variation, and polymorphisms in the APOE promoter region have been proposed to participate in the regulation of serum lipid levels within the most common APOE epsilon3/epsilon3 genotype group. We determined APOE -219G/T and +113G/C promoter genotypes and estimated APOE haplotypes in 525 participants of the Cardiovascular Risk in Young Finns Study. We studied the associations of the APOE promoter polymorphisms and their haplotypes with cross-sectional and longitudinal serum lipid and apolipoprotein concentrations as well as with flow-mediated dilatation (FMD), carotid artery compliance (CAC), and intima-media thickness (IMT) within the APOE epsilon3/epsilon3 carriers. We found no significant association between the APOE promoter genotypes and serum lipids [low density lipoprotein-cholesterol (LDL-C), HDL-C, and triglycerides], apolipoproteins (apoA-I and apoB), or brachial artery FMD, CAC, or carotid IMT in either men or women. In longitudinal analyses in males, the carriers of heterozygous genotypes (-219G/T or +113G/C) and, furthermore, carriers of the -219T/+113C/epsilon3 haplotype had significantly higher LDL-C and total cholesterol concentrations throughout the 21 year follow-up period compared with homozygous G allele carriers or noncarriers of the -219T/+113C/epsilon3 haplotype. Such associations were not found in females. In summary, the APOE promoter polymorphisms -219G/T and +113G/C as well as their haplotype are associated with longitudinal changes in LDL-C and total cholesterol concentrations in young Finnish males but do not seem to be major determinants for FMD, CAC, or carotid IMT in males or females.     

Screening of microbes for novel acidic cutinases and cloning and expression of an acidic cutinase from Aspergillus niger CBS 513.88

Isolates from gardening waste compost and 38 culture collection microbes were grown on agar plates at pH 4.0 with the cutinase model substrate polycaprolactone as a carbon source. The strains showing polycaprolactone hydrolysis were cultivated in liquid at acidic pH and the cultivations were monitored by assaying the p-nitrophenyl butyrate esterase activities. Culture supernatants of four strains were analyzed for the hydrolysis of tritiated apple cutin at different pHs. Highest amounts of radioactive hydrolysis products were detected at pHs below 5. The hydrolysis of apple cutin by the culture supernatants at acidic pH was further confirmed by GC–MS analysis of the hydrolysis products. On the basis of screening, the acidic cutinase from Aspergillus niger CBS 513.88 was chosen for heterogeneous production in Pichia pastoris and for analysis of the effects of pH on activity and stability. The recombinant enzyme showed activity over a broad range of pHs with maximal activity between pH 5.0 and 6.5. Activity could be detected still at pH 3.5.