Magnetic and elemental characterization of the particulate matter deposited on leaves of urban trees in Santiago, Chile.

Airborne particulate matter is a serious threat to human health, especially in fast-growing cities. In this study, we carried out a magnetic and elemental study on tree leaves used as passive captors and urban dust from various sites in the city of Santiago, Chile, to assess the reliability of magnetic and elemental measurements to characterize particulate matter pollution from vehicular origin. We found that the magnetic susceptibility and saturation isothermal remanent magnetization measured on urban tree leaves is a good proxy for tracing anthropogenic metallic particles and allow controlling the exposure time for particulate matter collection, in agreement with other studies carried out in large cities. Similar measurements on urban soil can be influenced by particles of detritic (natural) origin, and therefore, magnetic measurements on tree leaves can help to identify hotspots where fine particles are more abundant. Elemental particle-induced X-ray emission analysis of tree leaves showed the presence of a number of elements associated with vehicular emissions, in particular Cu, Zn, Fe, K and S which are present at every site, and As, Se, V, Ni, Sr, Zr, Mo and Pb identified at some sites. We observed a correlation between magnetic parameters and the concentrations of S and Br as well as Cu to a smaller extent. Moreover, this study shows the importance of selecting carefully the tree species as well as the location of trees in order to optimize phytoremediation.

In silico prediction of the enzymes involved in the degradation of the herbicide molinate by Gulosibacter molinativorax ON4T.

Gulosibacter molinativorax ON4T is the only known organism to produce molinate hydrolase (MolA), which catalyses the breakdown of the thiocarbamate herbicide into azepane-1-carboxylic acid (ACA) and ethanethiol. A combined genomic and transcriptomic strategy was used to fully characterize the strain ON4T genome, particularly the molA genetic environment, to identify the potential genes encoding ACA degradation enzymes. Genomic data revealed that molA is the only catabolic gene of a novel composite transposon (Tn6311), located in a novel low copy number plasmid (pARLON1) harbouring a putative T4SS of the class FATA. pARLON1 had an ANI value of 88.2% with contig 18 from Agrococcus casei LMG 22410T draft genome. Such results suggest that pARLON1 is related to genomic elements of other Actinobacteria, although Tn6311 was observed only in strain ON4T. Furthermore, genomic and transcriptomic data demonstrated that the genes involved in ACA degradation are chromosomal. Based on their overexpression when growing in the presence of molinate, the enzymes potentially involved in the heterocyclic ring breakdown were predicted. Among these, the activity of a protein related to caprolactone hydrolase was demonstrated using heterologous expression. However, further studies are needed to confirm the role of the other putative enzymes.

Complete genome sequence of the Radiation-Resistant bacterium Rubrobacter radiotolerans RSPS-4.

Rubrobacter radiotolerans strain RSPS-4 is a slightly thermophilic member of the phylum "Actinobacteria" isolated from a hot spring in São Pedro do Sul, Portugal. This aerobic and halotolerant bacterium is also extremely resistant to gamma and UV radiation, which are the main reasons for the interest in sequencing its genome. Here, we present the complete genome sequence of strain RSPS-4 as well as its assembly and annotation. We also compare the gene sequence of this organism with that of the type strain of the species R. radiotolerans isolated from a hot spring in Japan. The genome of strain RSPS-4 comprises one circular chromosome of 2,875,491 bp with a G+C content of 66.91%, and 3 circular plasmids of 190,889 bp, 149,806 bp and 51,047 bp, harboring 3,214 predicted protein coding genes, 46 tRNA genes and a single rRNA operon.

Expression of genes encoding extracellular matrix macromolecules and metalloproteinases in avian tibial dyschondroplasia.

Avian tibial dyschondroplasia (TD) is a skeletal disease characterized by disruption of endochondral bone formation. The aim of this study was to determine the expression of extracellular matrix (ECM) macromolecules and ECM-degrading enzymes [matrix metalloproteinases (MMPs)] in the growth plates of normal and TD-affected 3-week-old broiler chicks (Cobb strain). Protein levels were analyzed by immunoblotting and gelatin zymography and gene expression by polymerase chain reaction. Expression of genes encoding the ECM macromolecules (collagen types II, IX, X and XI; and aggrecan) was not altered in dyschondroplasia; however, there was down-regulation of genes encoding MMP-9, MMP-13, MMP-10 and MMP-11 in addition to reduced amounts of MMP-2 and MMP-13 proteins. In contrast, there was up-regulation of genes encoding MMP-7 and the vascular endothelial growth factor. These findings suggest that the accumulation of cartilage associated with the disease may be the result of decreased proteolysis due to the down-regulation of MMPs and not to an increased production of ECM macromolecules.

The saposin-like domain of the plant aspartic proteinase precursor is a potent inducer of vesicle leakage.

A unique feature of plant aspartic proteinase precursors is the presence of an internal domain, known as plant-specific insert, whose function is not completely understood. The three-dimensional structure of the plant-specific insert resembles that of saposin-like proteins, a group of lipid-binding proteins involved in a variety of physiological processes. Here we show that recombinant plant-specific insert is able to interact with phospholipid vesicles and to induce leakage of their contents in a pH- and lipid-dependent manner. The leakage activity is higher at pH 4.5 and requires the presence of acidic phospholipids such as phosphatidylserine. To determine whether the same effect could be observed when the plant-specific insert is part of the precursor form, procardosin A and a mutant form lacking this specific domain were produced and characterized. Procardosin A displays a similar activity profile, whereas the mutant without the plant-specific insert shows only residual activity. These findings indicate that the plant-specific insert domain of plant aspartic proteinases mediates an interaction of their precursors with phospholipid membranes and induces membrane permeabilization. It is therefore possible that the plant-specific insert, alone or in conjunction with the proteolytic activity of plant aspartic proteinases, may function either as a defensive weapon against pathogens or in late autolysis of plant cells.