Processing of a membrane protein required for cell-to-cell signaling during endospore formation in Bacillus subtilis

Activation of the late prespore-specific RNA polymerase sigma factor sigma(G) during Bacillus subtilis sporulation coincides with completion of the engulfment process, when the prespore becomes a protoplast fully surrounded by the mother cell cytoplasm and separated from it by a double membrane system. Activation of sigma(G) also requires expression of spoIIIJ, coding for a membrane protein translocase of the YidC/Oxa1p/Alb3 family, and of the mother cell-specific spoIIIA operon. Here we present genetic and biochemical evidence indicating that SpoIIIAE, the product of one of the spoIIIA cistrons, and SpoIIIJ interact in the membrane, thereby linking the function of the spoIIIJ and spoIIIA loci in the activation of sigma(G). We also show that SpoIIIAE has a functional Sec-type signal peptide, which is cleaved during sporulation. Furthermore, mutations that reduce or eliminate processing of the SpoIIIAE signal peptide arrest sporulation following engulfment completion and prevent activation of sigma(G). SpoIIIJ-type proteins can function in cooperation with or independently of the Sec system. In one model, SpoIIIJ interacts with SpoIIIAE in the context of the Sec translocon to promote its correct localization and/or topology in the membrane, so that it can signal the activation of sigma(G) following engulfment completion.     

Inhibition of 2-oxoglutarate dehydrogenase in potato tuber suggests the enzyme is limiting for respiration and confirms its importance in nitrogen assimilation,

The 2-oxoglutarate dehydrogenase complex constitutes a mitochondrially localized tricarboxylic acid cycle multienzyme system responsible for the conversion of 2-oxoglutarate to succinyl-coenzyme A concomitant with NAD(+) reduction. Although regulatory mechanisms of plant enzyme complexes have been characterized in vitro, little is known concerning their role in plant metabolism in situ. This issue has recently been addressed at the cellular level in nonplant systems via the use of specific phosphonate inhibitors of the enzyme. Here, we describe the application of these inhibitors for the functional analysis of the potato (Solanum tuberosum) tuber 2-oxoglutarate dehydrogenase complex. In vitro experiments revealed that succinyl phosphonate (SP) and a carboxy ethyl ester of SP are slow-binding inhibitors of the 2-oxoglutarate dehydrogenase complex, displaying greater inhibitory effects than a diethyl ester of SP, a phosphono ethyl ester of SP, or a triethyl ester of SP. Incubation of potato tuber slices with the inhibitors revealed that they were adequately taken up by the tissue and produced the anticipated effects on the in situ enzyme activity. In order to assess the metabolic consequences of the 2-oxoglutarate dehydrogenase complex inhibition, we evaluated the levels of a broad range of primary metabolites using an established gas chromatography-mass spectrometry method. We additionally analyzed the rate of respiration in both tuber discs and isolated mitochondria. Finally, we evaluated the metabolic fate of radiolabeled acetate, 2-oxoglutarate or glucose, and (13)C-labeled pyruvate and glutamate following incubation of tuber discs in the presence or absence of either SP or the carboxy ethyl ester of SP. The data obtained are discussed in the context of the roles of the 2-oxoglutarate dehydrogenase complex in respiration and carbon-nitrogen interactions.     

Validation of the Macrophyte Quality Index (MaQI) set up to assess the ecological status of Italian marine transitional environments

The paper couples the results obtained by applying the expert and the rapid Macrophyte Quality Indices set up to assess the ecological status of the Italian transitional environments according to the requirements by the Water Framework Directive (2000/60/CE). The indices were validated by comparing the composition of the macrophyte assemblages and the values of some bio-physico-chemical parameters of the water column of 20 stations of the Venice lagoon sampled monthly for one year between 2003 and 2005. In 5 stations out of the 20, the ones which fall within the 5 classes of ecological status suggested by the Water Framework Directive, sedimentation rates, sediment grain-size, and nutrient and pollutant (metals, Polychloro-Dibenzo-Dioxins/Furans, Polycyclic Aromatic Hydrocarbons, Pesticides and Polychlorinated Biphenils) concentrations in surface sediments were also determined. Results showed strong relationships between the trends of these environmental parameters and the composition and structure of macrophyte associations, as well as with the Macrophyte Quality Index assessment. Chlorophyceae showed a trend opposite to Rhodophyceae whose presence was concentrated in oxygenated and transparent environments. Chlorophyceae and the species characterised by low scores prevailed in turbid areas where nutrient and pollutant concentrations were high. Results allowed the identification of the conditions of the “reference sites” (confinement areas and sites with high water renewal) and the integration of the dichotomic key used for the application of the R-MaQI. Handling editor: S. M. Thomaz     

Hyperspectral remote detection of niche partitioning among canopy trees driven by blowdown gap disturbances in the Central Amazon

Advanced recruitment and neutral processes play important roles in determining tree species composition in tropical forest canopy gaps, with few gaps experiencing clear secondary successional processes. However, most studies are limited to the relatively limited spatial scales provided by forest inventory plots, and investigations over the entire range of gap size are needed to better understand how ecological processes vary with tree mortality events. This study employed a landscape approach to test the hypothesis that tree species composition and forest structural attributes differ between large blowdown gaps and relatively undisturbed primary forest. Spectral mixture analysis on hyperspectral satellite imagery was employed to direct field sampling to widely distributed sites, and blowdown plots were compared with undisturbed primary forest plots. Tree species composition and forest structural attributes differed markedly between gap and non-gap sites, providing evidence of niche partitioning in response to disturbance across the region. Large gaps were dominated by classic Neotropical pioneer genera such as Cecropia and Vismia, and average tree size was significantly smaller. Mean wood density of trees recovering in large gaps (0.55 g cm⁻³) was significantly lower than in primary forest plots (0.71 g cm⁻³), a difference similar to that found when comparing less dynamic (i.e., tree recruitment, growth, and mortality) Central Amazon forests with more dynamic Western Amazon forests. Based on results, we hypothesize that the importance of neutral processes weaken, and niche processes strengthen, in determining community assembly along a gradient in gap size and tree mortality intensity. Over evolutionary time scales, pervasive dispersal among colonizers could result in the loss of tree diversity in the pioneer guild through competitive exclusion. Results also underscore the importance of considering disturbance processes across the landscape when addressing forest carbon balance.     

Biochemical investigation of the effects of human platelet releasates on human articular chondrocytes

The aim of the present study was to demonstrate the mitogenic and differentiating properties of platelet‐rich plasma releasates (PRPr) on human chondrocytes in mono‐ and three‐dimensional cultures. In order to assess if PRPr supplementation could maintain the chondrocyte phenotype or at least inhibit the cell de‐differentiation even after several days in culture, we performed a proteomic study on several cell cultures independently grown, for different periods of time, in culture medium with FCS, human serum (HS), and releasates obtained from PRP and platelet‐poor plasma (PPP). We found that PRP treatment actually induced in chondrocytes the expression of proteins (some of which novel) involved in differentiation. J. Cell. Biochem. 108: 1153–1165, 2009. © 2009 Wiley‐Liss, Inc.     

The potential of Metarhizium anisopliae and Beauveria bassiana isolates for the control of Aedes aegypti (Diptera: Culicidae) larvae

Fungal isolates were screened against Aedes aegypti larvae. Exposure of larvae to conidial suspensions resulted in 6–90% mortality. An inoculum persistence assay using one of the most virulent isolates showed an approximate half-life of 10 days in water containers. Not all larvae surviving to form pupae resulted in adult emergence.     

Assessing changes in the conservation status of threatened Brazilian vertebrates

Threatened species assessments are one of the tools used to evaluate the degree of human impact on biodiversity, particularly in the assignment of extinction probabilities to individual species. Heavily altered habitats or biomes harbor a high proportion of the threatened species that have been assessed globally—80% of all of threatened species in IUCN’s Red List owe their poor status at least partly to the loss of habitat. Some taxonomic groups, however, may be well represented in the Red Lists either because they are naturally more sensitive to the most pervasive threats, or simply because they have been better studied. Here we look at the threat patterns on a temporal scale of Brazilian animal species included in the IUCN Red List, evaluating the hypotheses that directions of changes in red list status can be explained by the increase in scientific knowledge or by actual changes in threat factors. We analyzed changes in patterns of threatened vertebrates in IUCN’s list between 2002 and 2006. During that period, 120 species changed their status. 42 of these changes referred to inclusions and 78 to changes of threat category. For the latter group, 23 had their status upgraded to categories of higher threat, and 55 downgraded to others of lower threat. Most of the downgrades were caused by increase in scientific knowledge, while most of the upgrades resulted from the deterioration of the environmental conditions.     

Synthesis and evaluation of new endomorphin analogues modified at the Pro2 residue

Six new endomorphin analogues, incorporating constrained amino acids in place of native proline have been synthesized. Residues of (S)-azetidine-2-carboxylic acid (Aze), 3,4-dehydro-(S)-proline (Δ³Pro), azetidine-3-carboxylic acid (3Aze) and dehydro-alanine (ΔAla) have been used to prepare [Δ³Pro²]EM-2 (1), [Aze²]EM-1 (2), [Aze²]EM-2 (3), [3Aze²]EM-1 (4), [3Aze²]EM-2 (5) and [ΔAla²]EM-2 (6). Binding assays and functional bioactivities for μ- and δ-receptors are reported. The highest affinity, bioactivity and selectivity are shown by peptides 2 and 3 containing the Aze residue.     

Indolyl-pyrrolone as a new scaffold for Pim1 inhibitors

Pim1 belongs to a family of serine/threonine kinases, which is involved in the control of cell growth, differentiation, and apoptosis. Pim1 plays a pivotal role in cytokine signaling and is implicated in the development of a large number of tumors, representing a very attractive target for anticancer therapy. In this work, we applied a virtual screening protocol aimed at identifying small molecules able to inhibit Pim1 activity. The search of novel inhibitors was performed through a structure-based molecular modeling approach, taking advantage of the availability of the three-dimensional crystal structure of inhibitors bound to Pim1. Starting from the knowledge of protein–ligand complexes, the software LigandScout was used to generate pharmacophoric models, in turn used as queries to perform a virtual screening of databases, followed by docking experiments. As a result, a restricted set of candidates for biological testing was identified. Finally, among the six compounds selected as potential inhibitors of Pim1, two candidates endowed with a significant activity against Pim1 emerged. Interestingly, one of these compounds has a chemical scaffold different from inhibitors previously identified.