How are local fish communities structured in Brazilian semiarid headwater streams?

The spread of antibiotic-resistant bacteria is a threatening risk for human health at a global scale. Improved knowledge on the cycle of antibiotic resistance spread between human and the environment is a major requirement for the management of the current crisis. Compared to the well-studied cycle in clinical settings much less is known about the factor allowing their persistence in the environment. In fact, lakes and rivers exposed to high anthropogenic impact seem to become long-term reservoirs for resistance genes. The presence of antibiotic resistance genes (ARGs) within the resident microbiome of large subalpine lakes (i.e. Lake Geneva, Lake Maggiore) has recently been investigated in both the water column and the sediment. These studies suggest a correlation between the abundance of some ARGs and the anthropogenic impact. Within the system, however, abiotic factors and the food-web structure determine the survival of specific bacterial genotypes and thus the resistance genes they harbour. Thus, a growing body of work suggests an important role of ecological interactions in the persistence or elimination of such genes from the environment. This article reviews the current literature regarding the presence of ARGs in subalpine lakes, the impact of anthropogenic pollution on their appearance and the potential role of various ecological interactions on their persistence in the system.     

Application of the direct beta counter Matrix 96 for cytotoxic assays: Simultaneous processing and reading of 96 wells using a51Cr-retention assay

To assess the cytotoxic activity of immune cells, we have developed a⁵¹Cr-retention assay in which the radioactivity retained by⁵¹Cr-labeled target cells, following coincubation with cytotoxic cells, is monitored using the automated Matrix 96 beta counter. The Matrix 96 is designed for simultaneously counting 96 samples isolated from a 96-well microplate. It uses 96 uniform and independent detectors operating on the principle of avalanche gas ionization in the Geiger-Muller mode. Samples must be dry because the detectors are of the open-window type. Therefore, samples from the 96 wells of the microplate are simultaneously harvested onto a filter using the MicroMate 196, a 96-well cell harvester, dried and quantified in the Matrix 96. Usually the⁵¹Cr isotope is measured by the detection of gamma radiation in gamma counters. The Matrix 96, however, monitors Auger electrons, which are also emitted by⁵¹Cr. We have shown that the retention assay can be used to monitor the cytotoxic activity of activated lymphocytes including lymphokine-activated killer cells and tumor-infiltrating lymphocytes against various tumor cell lines. This assay is most suitable for experiments in which low E/T ratios are sufficient to detect highly cytotoxic cells, such as clone screening in cloning assays or in limiting-dilution analysis assays. These assays involve processing and reading large numbers of microplates. In this case, the retention assay monitored in the Matrix 96 will improve the work flow and decrease the amount of radioactive waste.This work was supported by the American Cancer Society grant IN-162-C     

In vitro evaluation of leptin fragments activity on the ob receptor.

In an attempt to identify regions in the leptin molecule responsible for its bioactivity, we tested six related-leptin peptide fragments denoted: Ac-hLEP(23-47)-NH(2) (I), Ac-hLEP(48-71)-NH(2) (II), Ac-hLEP(72-88)-NH(2) (III), Ac-hLEP(92-115)-NH(2) (IV), Ac-[Ser(117)]-hLEP(116-140)-NH(2) (V), Ac-hLEP(141-164)-NH(2) (VI) and their correspondent disulfide bridged dimer forms. The activity of the fragments was evaluated in comparision to leptin, by their ability to interact with leptin receptor using a cytosensor microphysiometer. Our results indicated that the fragments IV and V and [D-Leu(4)]-OB(3) and its human sequence analog were recognized by leptin receptor present in HP-75 cells, in agreement with the results obtained by other workers, validating that this region of the molecule contain the functional epitope of the leptin molecule.     

Tryptamine and dimethyltryptamine inhibit indoleamine 2,3 dioxygenase and increase the tumor‐reactive effect of peripheral blood mononuclear cells

Indoleamine 2,3‐dioxygenase (IDO) is an interferon‐γ (IFN‐γ)–induced tryptophan‐degrading enzyme, producing kynurenine (KYN) that participates in the mechanism of tumor immune tolerance. Thus, IDO inhibition has been considered a strategy for anticancer therapy. The aim of this study was to identify whether the metabolites originated from the competitive routes of tryptophan metabolism, such as the serotonergic or N, N‐dimethyltryptamine (DMT) pathways, have inhibitory effects on recombinant human IDO (rhIDO) activity. Serotonin and melatonin had no effect; on the other hand, tryptamine (TRY) and DMT modulated the activity of rhIDO as classical non‐competitive inhibitors, with Ki values of 156 and 506 μM, respectively. This inhibitory effect was also observed on constitutively expressed or IFN‐γ–induced IDO in the A172 human glioma cell line. TRY and DMT increased the cytotoxic activity of peripheral blood mononuclear cells (PBMCs) in co‐culture assays. We conclude that the IDO inhibition by TRY and DMT contributed to a more effective tumor‐reactive response by the PBMCs. Copyright © 2013 John Wiley & Sons, Ltd.     

State-of-knowledge on Astronium fraxinifolium Schott (Anacardiaceae) for genetic conservation in Brazil

This study explores the basis for conservation action on Astronium fraxinifolium Schott (Anacardiaceae). This is a wide-ranging forest species occurring in Brazil and other South American countries, and typical of gallery forest along watercourses in the Cerrado region. Information about this species is scanty and scattered. This paper aims to provide a structured review of available knowledge of its biology, ecology, silviculture and management. Widely-scattered published reports have been critically considered and efforts made to highlight and resolve contradictions and inconsistencies. Because little effort has been applied to its domestication and improvement, knowledge of silviculture and management of Astronium fraxinifolium is particularly meagre. Gaps in current knowledge relevant for conservation are identified and steps to fill them proposed. Where in situ conservation was considered appropriate, recommendations are made for the location of additional protected areas. Complementary ex situ and enrichment conservation action is suggested for specific parts of the range where resource losses are already so extensive that in situ measures alone are insufficient. Provision for refining the limited management and conservation knowledge is made through highlighting priorities for study of the taxon. Finally, future action is discussed in the context of the infrastructure of the national conservation sector of Brazil.     

Toxocara canis and the allergic process

The protective effect of infectious agents against allergic reactions has been thoroughly investigated. Current studies have demonstrated the ability of some helminths to modulate the immune response of infected hosts. The objective of the present study was to investigate the relationship between Toxocara canis infection and the development of an allergic response in mice immunised with ovalbumin (OVA). We determined the total and differential blood and bronchoalveolar lavage fluid cells using BALB/c mice as a model. To this end, the levels of interleukin (IL)-4, IL-5 and IL-10 and anti-OVA-IgE were measured using an ELISA. The inflammatory process in the lungs was observed using histology slides stained with haematoxylin and eosin. The results showed an increase in the total number of leukocytes and eosinophils in the blood of infected and immunised animals at 18 days after infection. We observed a slight lymphocytic inflammatory infiltrate in the portal space in all infected mice. Anti-OVA-IgE levels were detected in smaller proportions in the plasma of immunised and infected mice compared with mice that were only infected. Therefore, we concluded that T. canis potentiates inflammation in the lungs in response to OVA, although anti-OVA-IgE levels suggest a potential reduction of the inflammatory process through this mechanism.     

Comparative proteomic analysis of four biotechnological strains Lactococcus lactis through label-free quantitative proteomics

Lactococcus lactis is a bacteria with high biotechnological potential, where is frequently used in the amino acid production and production of fermented dairy products, as well as drug delivery systems and mucosal vaccine vector. The knowledge of a functional core proteome is important extremely for both fundamental understanding of cell functions and for synthetic biology applications. In this study, we characterized the L. lacits proteome from proteomic analysis of four biotechnological strains L. lactis: L. lactis subsp. lactis NCDO2118, L. lactis subsp. lactis IL1403, L. lactis subsp. cremoris NZ9000 and L. lactis subsp. cremoris MG1363. Our label-free quantitative proteomic analysis of the whole bacterial lysates from each strains resulted in the characterization of the L. lactis core proteome that was composed by 586 proteins, which might contribute to resistance of this bacterium to different stress conditions as well as involved in the probiotic characteristic of L. lactis. Kegg enrichment analysis shows that ribosome, metabolic pathways, pyruvate metabolism and microbial metabolism in diverse environments were the most enriched. According to our quantitative proteomic analysis, proteins related to translation process were the more abundant in the core proteome, which represent an important step in the synthetic biology. In addition, we identified a subset of conserved proteins that are exclusive of the L. lactis subsp. cremoris or L. lactis subsp. lactis, which some are related to metabolic pathway exclusive. Regarding specific proteome of NCDO2118, we detected ‘strain-specific proteins’. Finally, proteogenomics analysis allows the identification of proteins, which were not previously annotated in IL1403 and MG1363. The results obtained in this study allowed to increase our knowledge about the biology of L. lactis, which contributes to the implementation of strategies that make it possible to increase the biotechnological potential of this bacterium.     

Activation of Leishmania (Leishmania) amazonensis arginase at low temperature by binuclear Mn center formation of the immobilized enzyme on a Ni resin

In Leishmania, arginase is responsible for the production of ornithine, a precursor of polyamines required for proliferation of the parasite. In this work, the activation kinetics of immobilized arginase enzyme from L. (L.) amazonensis were studied by varying the concentration of Mn²⁺ applied to the nickel column at 23 °C. The intensity of the binding of the enzyme to the Ni²⁺ resin was directly proportional to the concentration of Mn²⁺. Conformational changes of the enzyme may occur when the enzyme interacts with immobilized Ni²⁺, allowing the following to occur: (1) entrance of Mn²⁺ and formation of the metal bridge; (2) stabilization and activation of the enzyme at 23 °C; and (3) an increase in the affinity of the enzyme to Ni²⁺ after the Mn²⁺ activation step. The conformational alterations can be summarized as follows: the interaction with the Ni²⁺ simulates thermal heating in the artificial activation by opening a channel for Mn²⁺ to enter.