Structural and functional role of Domain I for the insecticidal activity of the Vip3Aa protein from Bacillus thuringiensis

Vip3 proteins are produced by Bacillus thuringiensis and are toxic against lepidopterans, reason why the vip3Aa gene has been introduced into cotton and corn to control agricultural pests. Recently, the structure of Vip3 proteins has been determined and consists of a tetramer where each monomer is composed of five structural domains. The transition from protoxin to the trypsin-activated form involves a major conformational change of the N-terminal Domain I, which is remodelled into a tetrameric coiled-coil structure that is thought to insert into the apical membrane of the midgut cells. To better understand the relevance of this major change in Domain I for the insecticidal activity, we have generated several mutants aimed to alter the activity and remodelling capacity of this central region to understand its function. These mutants have been characterized by proteolytic processing, negative staining electron microscopy, and toxicity bioassays against Spodoptera exigua. The results show the crucial role of helix α1 for the insecticidal activity and in restraining the Domain I in the protoxin conformation, the importance of the remodelling of helices α2 and α3, the proteolytic processing that takes place between Domains I and II, and the role of the C-t Domains IV and V to sustain the conformational change necessary for toxicity.     

Benthic macroinvertebrate assemblages detect the consequences of a sewage spill: a case study of a South American environmental challenge

Limnology - Benthic macroinvertebrate assemblages are used to assess anthropogenic stressors and pressures globally—although considerable spatial and temporal variability in those assemblages...     

Chemoecological study of the invasive alga Caulerpa taxifolia var. distichophylla from the Sicilian coast

Aquatic Ecology - Marine invasive species and their bioactive metabolites have become critical ecological issues in the Mediterranean Sea. In particular, the highly invasive green algae Caulerpa...     

Palaeoecological implications of the sympatric distribution of two species of Machairodus (Felidae,Machairodontinae, Homotherini) in the Late Miocene of Los Valles de Fuentidueña (Segovia,Spain)

In this paper, we study a sample of cranial, mandibular and dental remains of two species of the machairodontine felid genus Machairodus from the Early Vallesian (MN 9, around 10 Ma) site of Los Valles de Fuentidueña (Segovia, Spain): the tiger-sized Machairodus aphanistus, and the smaller and more primitive M. alberdiae; a species which is only known from this site. The fossils of these two sympatric populations are compared with the most abundant samples of M. aphanistus from the Late Vallesian (MN 10), younger sites of Batallones-1 and Batallones-3 (Torrejón de Velasco, Madrid, Spain). The results support the specific separation of M. alberdiae from M. aphanistus based on several differences in teeth size and proportions. Besides this, we observed differences among the analysed samples of M. aphanistus, indicating a differentiation between the older and more primitive form from Los Valles de Fuentidueña, and the younger and more derived one from the two Batallones sites. These differences fit well with the morphological evolution of this lineage towards the more derived Turolian Amphimachairodus giganteus. Finally, a relatively structured, patched habitat, combining the presence of open landscapes with shrubby and wooded areas, is inferred to explain the sympatric distribution of these two large machairodontines in Los Valles de Fuentidueña.     

Antifungal effects of the flavonoids kaempferol and quercetin: a possible alternative for the control of fungal biofilms

This study aimed to determine the minimum inhibitory concentration (MIC) of kaempferol and quercetin against planktonic and biofilm forms of the Candida parapsilosis complex. Initially, nine C. parapsilosis sensu stricto, nine C. orthopsilosis and nine C. metapsilosis strains were used. Planktonic susceptibility to kaempferol and quercetin was assessed. Growing and mature biofilms were then exposed to the flavonoids at MIC or 10xMIC, respectively, and theywere also analyzed by confocal laser scanning microscopy. The MIC ranges were 32-128 µg ml^?1 for kaempferol and 0.5-16 µg ml^?1 for quercetin. Kaempferol and quercetin decreased (P?<?0.05) the metabolic activity and biomass of growing biofilms of the C. parapsilosis complex. As for mature biofilms, the metabolic effects of the flavonoids varied, according to the cryptic species, but kaempferol caused an overall reduction in biofilm biomass. Microscopic analyses showed restructuring of biofilms after flavonoid exposure. These results highlight the potential use of these compounds as sustainable resources for the control of fungal biofilms.     

Metal‐responsive RNA polymerase extracytoplasmic function (ECF) sigma factors

In order to survive, bacteria must adapt to multiple fluctuations in their environment, including coping with changes in metal concentrations. Many metals are essential for viability, since they act as cofactors of indispensable enzymes. But on the other hand, they are potentially toxic because they generate reactive oxygen species or displace other metals from proteins, turning them inactive. This dual effect of metals forces cells to maintain homeostasis using a variety of systems to import and export them. These systems are usually inducible, and their expression is regulated by metal sensors and signal‐transduction mechanisms, one of which is mediated by extracytoplasmic function (ECF) sigma factors. In this review, we have focused on the metal‐responsive ECF sigma factors, several of which are activated by iron depletion (FecI, FpvI and PvdS), while others are activated by excess of metals such as nickel and cobalt (CnrH), copper (CarQ and CorE) or cadmium and zinc (CorE2). We focus particularly on their physiological roles, mechanisms of action and signal transduction pathways.     

Lipidomic profile as a noninvasive tool to predict endometrial receptivity

For the present study we asked whether the endometrial fluid lipidomic may be a useful approach to predict endometrial receptivity in freeze‐all cycles. For this case‐control study, endometrial fluid samples were collected from 41 patients undergoing freeze‐all cycles. Samples were split depending on the pregnancy outcome: positive group (n = 24) and negative group (n = 17). Data were acquired by the matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry. Principal component analysis (PCA) and partial least squares discriminant analysis (PLS‐DA) were applied. A list of potential biomarker ion ratios was obtained and the values were used to build a receiver operating characteristic (ROC) curve to predict pregnancy success. The lipid categories were attributed by LIPID MAPS database. Ion ratios were established according to their correlations and used for the analysis. The PCA showed a tendency of separation between the studied groups, whereas the PLS‐DA was able to clearly distinguish them. Fifteen ratios (13 hyper‐represented in the negative and two hyper‐represented in the positive group) were selected according to their importance for model prediction. These ratios were used to build the ROC curve, which presented an area under curve of 84.0% (95%CI: 69.2–97.4%; p = 0.009). These findings suggest that lipidomic profiling of endometrial fluid may be a valuable tool for identifying the time interval comprising the window of implantation.     

Lung specific developmental expression of the Xenopus laevis surfactant protein C and B genes

Efforts to characterize the mechanisms underlying early lung development have been confounded by the absence of a model that permits study of lung development prior to the onset of endodermal differentiation. Since Xenopus laevis development occurs in an extrauterine environment, we sought to determine whether the classical molecular markers of lung development and function, surfactant protein genes, are expressed in X. laevis. Surfactant protein C (SP-C) is a specific marker for lung development, expressed early in development and exclusively in the lung. Surfactant protein B (SP-B) expression is essential for life, as its absence results in neonatal death in mice and gene mutations have been associated with neonatal respiratory failure in humans. Here, we report the cloning of the first non-mammalian SP-C and SP-B genes (termed xSP-C and xSP-B) using the Xenopus model. The processed mature translated regions of both xSP-C and xSP-B have high homology with both human and mouse genes. xSP-C and xSP-B are both expressed throughout the lung of the X. laevis swimming tadpoles soon after the initiation of lung development as assessed by RT-PCR and whole mount in situ hybridization. The temporal expression patterns of xSP-C and xSP-B are consistent with the expression patterns in mammalian models of lung development. In both the tadpole and the adult X. laevis, xSP-C and xSP-B are expressed only in lung. Knowledge of the sequence and expression pattern of these two surfactant proteins in Xenopus might allow for use of this organism to study early lung development.     

Peptidase profiles from non-albicans Candida spp. isolated from the blood of a patient with chronic myeloid leukemia and another with sickle cell disease

Candida lipolytica and Candida rugosa were isolated from blood samples from a patient with chronic myeloid leukemia (31 years old) and a patient with sickle cell disease (1-year-old), respectively. Isolates were grown for 48 h at 37 degrees C in either Sabouraud or tryptone soy broth (TSB). Peptidases were tested for using substrate sodium dodecyl sulfate-polyacrylamide gels with gelatin, casein, bovine serum albumin (BSA) or hemoglobin. Enzymography analyses were made on the following substrates: human albumin, IgG and human fibrinogen, which had been incubated with the concentrated supernatants. For C. lipolytica, a approximately 60-kDa gelatin-degrading serine proteolytic activity was found in the TSB supernantant as well as a metallopeptidase activity capable of hydrolysing human albumin, IgG and human fibrinogen. With C. rugosa, albumin, IgG and human fibrinogen substrates were degraded by an aspartyl-like peptidase activity. Supernatants from C. rugosa also showed three serine proteolytic activities towards gelatin (approximately 50 kDa, TSB), casein ( approximately 94 kDa, TSB) and BSA ( approximately 120-kDa, Sabouraud), in addition to a metallopeptidase capable of degrading casein ( approximately 110 kDa, Sabouraud). Little is known about peptidases of C. rugosa and C. lipolytica and this preliminary data may prove useful for future work on host-parasite relationship and antifungal agents.