Response of transglutaminase activity and bound putrescine to changes in light intensity under natural or controlled conditions in Quercus ilex leaves

In order to further study a previously observed relationship between polyamine (PA) content and changes in irradiation, we examined the level of free and bound PAs, the activity of transglutaminase (TGase, EC 2.3.2.13) and chlorophyll fluorescence in holm oak ( Quercus ilex L.) leaves in response to different levels of light intensity and amount. A diurnal trend of free and bound putrescine (F-Put and B-Put, respectively) and TGase activity was observed in plants under natural conditions in the forest, with the highest value corresponding to the maximum light intensity and amount of light received by the leaves. In another set of experiments, potted Q. ilex plants in experimental fields were subjected to a range of periods of natural photosynthetic photon flux density (PPFD) by covering or not covering the whole trees. Under a natural photoperiod (uncovered leaves), B-Put content and TGase activity paralleled the diurnal PPFD pattern, reaching a maximum at the highest PPFD; prior to this maximum, free PAs showed a significant rise. Plants that were in darkness until midday and suddenly exposed to high light intensity showed enhanced TGase activity, resulting in the maximum accumulation of B-Put. The involvement of the accumulation of B-Put reflected in the changes of the B-Put/bound spermidine ratio during the photoprotective responses to high light stress in forest plants is discussed in relation to the chlorophyll fluorescence parameters observed.     

YhdJ, a nonessential CcrM-like DNA methyltransferase of Escherichia coli and Salmonella enterica

The Caulobacter crescentus DNA adenine methyltransferase CcrM and its homologs in the alpha-Proteobacteria are essential for viability. CcrM is 34% identical to the yhdJ gene products of Escherichia coli and Salmonella enterica. This study provides evidence that the E. coli yhdJ gene encodes a DNA adenine methyltransferase. In contrast to an earlier report, however, we show that yhdJ is not an essential gene in either E. coli or S. enterica.     

Functional and structural characterization of the first prokaryotic member of the L-amino acid transporter (LAT) family: a model for APC transporters

We have identified YkbA from Bacillus subtilis as a novel member of the L-amino acid transporter (LAT) family of amino acid transporters. The protein is approximately 30% identical in amino acid sequence to the light subunits of human heteromeric amino acid transporters. Purified His-tagged YkbA from Escherichia coli membranes reconstituted in proteoliposomes exhibited sodium-independent, obligatory exchange activity for L-serine and L-threonine and also for aromatic amino acids, albeit with less activity. Thus, we propose that YkbA be renamed SteT (Ser/Thr exchanger transporter). Kinetic analysis supports a sequential mechanism of exchange for SteT. Freeze-fracture analysis of purified, functionally active SteT in proteoliposomes, together with blue native polyacrylamide gel electrophoresis and transmission electron microscopy of detergent-solubilized purified SteT, suggest that the transporter exists in a monomeric form. Freeze-fracture analysis showed spherical particles with a diameter of 7.4 nm. Transmission electron microscopy revealed elliptical particles (diameters 6 x 7 nm) with a distinct central depression. To our knowledge, this is the first functional characterization of a prokaryotic member of the LAT family and the first structural data on an APC (amino acids, polyamines, and choline for organocations) transporter. SteT represents an excellent model to study the molecular architecture of the light subunits of heteromeric amino acid transporters and other APC transporters.     

The <Emphasis Type="Italic">Prestige</Emphasis> oil spill: bacterial community dynamics during a field biostimulation assay

A field bioremediation assay using the oleophilic fertilizer S200 was carried out 12 months after the Prestige heavy fuel-oil spill on a beach on the Cantabrian coast (north Spain). This assay showed that S200-enhanced oil degradation, particularly of high-molecular-weight n-alkanes and alkylated PAHs, suggesting an increase in the microbial bioavailability of these compounds. The bacterial community structure was determined by cultivation-independent analysis of polymerase chain reaction-amplified 16S rDNA by denaturing gradient gel electrophoresis. Bacterial community was mainly composed of α-Proteobacteria (Rhodobacteriaceae and Sphingomonadaceae). Representatives of γ-Proteobacteria (Chromatiales, Moraxellaceae, and Halomonadaceae), Bacteroidetes (Flavobacteriaceae), and Actinobacteria group (Nocardiaceae and Corynebacteriaceae) were also found. The addition of the fertilizer led to the appearance of the bacterium Mesonia algae in the early stages, with a narrow range of growth substrates, which has been associated with the common alga Achrosiphonia sonderi. The presence of Mesonia algae may be attributable to the response of the microbial community to the addition of N and P rather than indicating a role in the biodegradation process. The Rhodococcus group appeared in both assay plots, especially at the end of the experiment. It was also found at another site on the Galician coast that had been affected by the same spill. This genus has been associated with the degradation of n-alkanes up to C₃₆. Taking into account the high content of heavy alkanes in the Prestige fuel, these microorganisms could play a significant role in the degradation of such fuel. A similar bacterial community structure was observed at another site that showed a similar degree of fuel weathering.     

Bacterial L-forms require peptidoglycan synthesis for cell division

Cell-wall-less bacterial variants, or L-forms, have been described in many bacterial species under laboratory conditions, in infected eukaryotic cell cultures and inside animals. Of special interest for human health is the formation of L-forms as a consequence of specific antibiotic treatments, and the potential involvement of L-forms in persistent and relapsing infections. An old enigma about L-forms is how they can divide in the absence of cell wall synthesis, since septum formation is an essential requisite for cell division. However, the classical definition of L-forms as cell-wall-less bacterial variants may need a revision to accommodate recent observations by Richard d'Ari and coworkers: genetic and biochemical evidence indicates that E. coli L-forms induced by beta-lactam antibiotics do contain small amounts of peptidoglycan, essential for their growth and probably required for septum formation. If these observations are extrapolated to all known L-forms, the very concept of cell-wall-less bacteria may need revision, and be restricted to mycoplasmas and their relatives.     

Simvastatin and atorvastatin enhance gene expression of collagen type 1 and osteocalcin in primary human osteoblasts and MG-63 cultures

To clarify the mechanism of the stimulatory effect of statins on bone formation, we have assessed the effect of simvastatin and atorvastatin on osteoblast activity by analysing cell proliferation, as well as collagen, osteocalcin, and bone morphogenetic protein-2 (BMP2) gene expression in primary human osteoblast (hOB) and MG-63 cell line cultures. Explants of bone from patients without any metabolic disease under orthopedic hip procedures were used to obtain hOB. Cell cultures were established, synchronized, and different concentrations of simvastatin or atorvastatin were added (10(-9) M, 10(-8) M, 10(-7) M, 10(-6) M) during the experiment. Cell proliferation was analyzed after 24 h. Collagen polypeptide alpha1 type 1 (COL1A1) gene expression, osteocalcin, and BMP2 expression levels were quantified by real-time PCR after 24 h incubation with statins. There was a statistically significant decrease in cell proliferation related to simvastatin or atorvastatin addition at all concentrations in primary hOB compared with those not treated. A significant increase in COL1A1, osteocalcin, and BMP2 gene expression was detected when hOB cultures were treated with simvastatin or atorvastatin at different concentrations. Similar but less significant effects were found on MG-63 cells. After statin treatment we observed both an arrest of proliferation in hOB cells and an increase in collagen, osteocalcin, and BMP2 gene expression, consistent with a stimulatory effect towards mature osteoblast differentiation. These findings support the bone-forming effect of statins, probably through the BMP2 pathway.     

Rodent acorn selection in a Mediterranean oak landscape

Quercus suber, Quercus ilex and Quercus coccifera (Cork, Holm and Kermes oaks, respectively) are common evergreen oak species that coexist in the landscapes of the western part of the Mediterranean basin. Rodents are the main acorn predators and thus one of the main factors for understanding recruitment patterns in oaks. In this paper we analyse to what extent mice prefer acorns from one oak species over another in three oak species studied using acorn removal experiments and video tape recordings. Twenty labelled acorns from each of the three Quercus species (60 acorns) were placed in 40 cm×40 cm quadrats on each plot. Because selection might vary as a result of the vegetation context, we performed the trials in the five main vegetation types within the study area (four replicates in each vegetation type) in order to control for habitat influences on rodent acorn preferences (a total of 20 plots). The removal of 1,200 acorns occurred within 68 days. Mice removed 98.7% of the acorns. Q. ilex acorns were preferred over Q. suber and Q. coccifera in all vegetation types except in pine forest, where no acorn preferences were detected. Acorn removal rates differed with vegetation type, correlating positively with shrub cover. The distance at which acorns were displaced by rodents (mean =4.6 m±5.1 SD) did not differ between acorn species, but varied among vegetation types. Bigger acorns of Q. coccifera were selected only after Q. ilex and Q. suber acorns were depleted, while no size selection was detected for the latter two species. Thus, we conclude that rodents show preference for some oak acorns and that landscape context contributes significantly to rodent activities and decisions.     

Cradle-to-gate study of red clay for use in the ceramic industry

Background, Goal and Scope  The ceramic tile industry is one of the most important industries in Spain, with the highest concentration of firms to be found in the province of Castellón on the Mediterranean coast. The basic input material for this industry is red clay. The aim of this study was to carry out an LCA of the process of mining, treating and marketing this clay in order to identify the stages and unit processes that have the greatest impact on the environment. This LCA examines all the stages of the red clay from cradle to the customer’s gate, including the process of mining and treating the clay in the mining facilities and its later distribution to end users. Methods  Life cycle inventory (LCI): An exhaustive LCI was performed by collecting data from the mine run by Watts Blake Bearne Spain, S.A. (WBB-Spain) in Castellón. Inputs and outputs were collected for all the unit processes involved in the mining, treatment and marketing of the clay: