A Three-protein Charge Zipper Stabilizes a Complex Modulating Bacterial Gene Silencing

The Hha/YmoA nucleoid-associated proteins help selectively silence horizontally acquired genetic material, including pathogenicity and antibiotic resistance genes and their maintenance in the absence of selective pressure. Members of the Hha family contribute to gene silencing by binding to the N-terminal dimerization domain of H-NS and modifying its selectivity. Hha-like proteins and the H-NS N-terminal domain are unusually rich in charged residues, and their interaction is mostly electrostatic-driven but, nonetheless, highly selective. The NMR-based structural model of the complex between Hha/YmoA and the H-NS N-terminal dimerization domain reveals that the origin of the selectivity is the formation of a three-protein charge zipper with interdigitated complementary charged residues from Hha and the two units of the H-NS dimer. The free form of YmoA shows collective microsecond-millisecond dynamics that can by measured by NMR relaxation dispersion experiments and shows a linear dependence with the salt concentration. The number of residues sensing the collective dynamics and the population of the minor form increased in the presence of H-NS. Additionally, a single residue mutation in YmoA (D43N) abolished H-NS binding and the dynamics of the apo-form, suggesting the dynamics and binding are functionally related.     

Understanding fungal functional biodiversity during the mitigation of environmentally dispersed pentachlorophenol in cork oak forest soils

Pentachlorophenol (PCP) is globally dispersed and contamination of soil with this biocide adversely affects its functional biodiversity, particularly of fungi – key colonizers. Their functional role as a community is poorly understood, although a few pathways have been already elucidated in pure cultures. This constitutes here our main challenge – elucidate how fungi influence the pollutant mitigation processes in forest soils. Circumstantial evidence exists that cork oak forests in N. W. Tunisia – economically critical managed forests are likely to be contaminated with PCP, but the scientific evidence has previously been lacking. Our data illustrate significant forest contamination through the detection of undefined active sources of PCP. By solving the taxonomic diversity and the PCP‐derived metabolomes of both the cultivable fungi and the fungal community, we demonstrate here that most strains (predominantly penicillia) participate in the pollutant biotic degradation. They form an array of degradation intermediates and by‐products, including several hydroquinone, resorcinol and catechol derivatives, either chlorinated or not. The degradation pathway of the fungal community includes uncharacterized derivatives, e.g. tetrachloroguaiacol isomers. Our study highlights fungi key role in the mineralization and short lifetime of PCP in forest soils and provide novel tools to monitor its degradation in other fungi dominated food webs.     

Sympatry between <Emphasis Type="Italic">Alouatta caraya</Emphasis> and <Emphasis Type="Italic">Alouatta clamitans</Emphasis> and the rediscovery of free-ranging potential hybrids in Southern Brazil

Records of sympatry between Alouatta caraya and A. clamitans are rare despite their extensive range overlap. An example of their current sympatry and the rediscovery of free-ranging potential hybrids of A. caraya and A. clamitans in the forests of the Upper Paraná River, Southern Brazil, are reported in this paper. Eight groups were observed in the study area: five monospecific groups of A. caraya, two of A. clamitans, and a group containing two adult males and two adult females of A. caraya and a sub-adult male and two adult females identified as Alouatta sp. The color of the last three individuals was a mosaic between the two species; this is consistent with previously described variations in museum specimens collected in the Paraná River in the 1940s that had been identified as potential hybrids. The results from this study emphasize the need for scientific studies in the region of the Ilha Grande National Park, one of the few regions in the Paraná River that currently harbors both howler species. Contribution number 1637 of the Departamento de Zoologia, Universidade Federal do Paraná, Caixa Postal 19020, 81531-980, Curitiba, Paraná, Brasil.     

Life cycle assessment of retaining wall backfilled with shredded tires

Purpose

This life cycle assessment (LCA) study compares energy consumption, greenhouse gas emissions, and environmental damages for two methods of constructing retaining structures, a traditional method involving a retaining wall backfilled with sand, and an alternative method involving a retaining wall backfilled with shredded tires.

Methods

Taking into account the extraction and production of the used construction materials, loading, transport and installation, the cumulative energy demand (CED), global warming potential (GWP), acidification potential, Human Health Criteria Air-mobile, aquatic eutrophication potential, ozone depletion potential, and smog potential is determined for each construction method. The seven environmental impact categories are calculated using the software tool, ATHENA® Environmental Impact Estimator (ATHENA® EIE) for Buildings v5.2.0118.

Results and discussion

The seven impact categories were reduced significantly by using shredded tires as retaining wall backfill; this is due to the decrease in the amounts of concrete, reinforcing steel, and fuel quantity consumed by building machines and vehicles transporting construction materials.

Conclusions

The study concludes that in all examined impact categories alternative method provides a larger environmental benefit than the traditional method. Also, the results clearly demonstrate that the use of shredded tires is very effective as a sustainable alternative to retaining structures.

     

DNA damage in peripheral blood of patients with chronic obstructive pulmonary disease (COPD)

Chronic obstructive pulmonary disease (COPD) is a condition characterized by chronic airway inflammation and remodeling, lung parenchymal inflammation, and destruction resulting in expiratory airflow obstruction, hyperinflation of the lung with loss of elastic recoil, and impairment of gas exchange. Skeletal muscles in individuals with COPD generate free radicals at rest, and production increases during contractile activity. Overproduction of free radicals may result in oxidant-antioxidant imbalance in favor of oxidants. This study evaluated the levels of genetic damage in peripheral blood of patients with COPD using the cytokinesis-blocked micronucleus (CBMN) and the comet assays. The study was conducted with 25 patients with COPD and 25 controls matched for age and sex. Results of both comet and CBMN assays showed an increase in the level of DNA damage. In the group of patients with COPD, the mean frequency of binucleate cells with micronuclei was 6.72+/-3.02, and in the control group, 4.20+/-2.08 (p=0.00233). Mean comet value was 26.84+/-19.61 in patients with COPD and 7.25+/-7.57 in the control group (p=0.00004). The increased frequency of micronuclei in patients with COPD was primarily assigned to clastogenic events and DNA amplification because the frequency of nucleoplasmic bridges and buds was also increased. Oxidative stress in lung cells is a constant source of free radicals that damage genetic material of both lung and circulating cells.