Greater macroinvertebrate diversity and freshwater mussel density in meander margins of an Amazon river

Meanders are complex aquatic environments exhibiting different flow and sediment characteristics that influence macroinvertebrate distribution. Differences in macroinvertebrate composition, freshwater mussel density (mainly Castalia ambigua Lamarck, 1819) and habitat variables were investigated, using uni‐ and multivariate analyses, in two zones, the margin and thalweg, of the meanders of a 7‐km stretch of a morphologically unaltered tropical alluvial lowland river. Clear differences were found between meander zones, with greater taxonomic and functional diversity of macroinvertebrates and greater freshwater mussel densities in the meander margin. A total of 12 families of macroinvertebrates were exclusive to the meander margin, and macroinvertebrate indicators of zones were Philopotamidae and Leptoceridae (meander margin) and Chironomidae and Elmidae (meander thalweg). In the meander margin, there were no differences in macroinvertebrate abundance, and taxonomic and functional group diversity among areas with low, medium and high mussel density. Macroinvertebrate abundance did not vary between zones, but in both, abundance was associated with lower pH and higher electrical conductivity. Low shear velocity, which stabilises the river bed, high organic matter content and percentage silt in the meander margin were associated with higher taxonomic and functional macroinvertebrate diversity, as well as the presence of freshwater mussels. Natural unaltered meanders are spatially heterogeneous in both habitat and biodiversity and, similar to restored meanders, support greater macroinvertebrate taxonomic and functional diversity, as well as maintain freshwater mussel beds, mainly by stabilising the river bed. The meander margin may also be important for attracting mussel host fish that feed on macroinvertebrates and aid mussel dispersal. Thus, the meander margins, and other similar riparian habitats with low shear velocity, for example, side channels and pools, have potentially high conservation value and should be afforded due protection.     

Structural and Functional Integration of the PLCγ Interaction Domains Critical for Regulatory Mechanisms and Signaling Deregulation

1. Download : Download high-res image (312KB)
2. Download : Download full-size image

Highlights? Domains from PLCγ regulatory region show structural and functional integration ? Only cSH2 domain interacts with the PLC-core forming a high affinity surface ? Activation involves removal of autoinhibition and dissociation from the receptor ? Disease-linked mutations map to the autoinhibitory interface     

Mechanical analysis of the ring opening test applied to human ascending aortas

This work presents experiments, modelling and numerical simulation aimed at describing the mechanical response of human ascending aortas in the ring opening test. The objective is to quantify, from the opening angles measured in the test, the residual stress distribution along the artery wall and, afterwards, how this stress pattern changes when the artery is subjected to standard physiological pressures. The cases studied correspond to four groups including both healthy and pathological arteries. The tissues are characterized via tensile test measurements that enable to derive the material parameters of two constitutive models adopted in the present analysis. Overall, the numerical results obtained for all groups were found to be a useful data that allow to estimate the residual stress and their influence on the vessels under normal and hypertension physiological conditions.     

Metformin protects against doxorubicin-induced cardiotoxicity: involvement of the adiponectin cardiac system

Doxorubicin has cardiotoxic effects that limit its clinical benefit in cancer patients. Metformin exerts cardioprotective actions via AMP-activated protein kinase (AMPK) and increases the expression of adiponectin and its receptors (adipoR1 and adipoR2) in skeletal muscle and adipose tissue, but its effect on cardiac tissue is still unknown. This work aimed to study whether metformin exerts any protective action against the cardiotoxicity of doxorubicin and whether the cardiac system of adiponectin is involved in any such action. The addition of doxorubicin (5μM) to adult mouse cardiomyocytes (HL-1 cell line) induced apoptosis, which was characterized by a loss of cell viability, activation of caspases, and fragmentation of the genetic material. Doxorubicin treatment also caused a decrease in the activity of the antioxidant enzymes catalase, glutathione peroxidase, and superoxide dismutase. Pretreatment with metformin (4mM, 24h) provided protection against doxorubicin-induced damage. This pretreatment significantly increased cell viability, attenuated the activation of caspases and the fragmentation of genetic material, and restored the antioxidant activity. In addition, metformin up-regulated the expression of adiponectin and its receptors, adipoR1 and adipoR2, in cardiomyocytes. In contrast, silencing either adipoR1 or adipoR2 with siRNA inhibited the AMPK activation and the protective effects of metformin. Taken together, these results demonstrate that metformin protects cardiomyocytes from doxorubicin-induced damage and that the cardiac adiponectin system plays an important role in this protective action.     

DNA barcoding identifies Argentine fishes from marine and brackish waters

Background

DNA barcoding has been advanced as a promising tool to aid species identification and discovery through the use of short, standardized gene targets. Despite extensive taxonomic studies, for a variety of reasons the identification of fishes can be problematic, even for experts. DNA barcoding is proving to be a useful tool in this context. However, its broad application is impeded by the need to construct a comprehensive reference sequence library for all fish species. Here, we make a regional contribution to this grand challenge by calibrating the species discrimination efficiency of barcoding among 125 Argentine fish species, representing nearly one third of the known fauna, and examine the utility of these data to address several key taxonomic uncertainties pertaining to species in this region.

Methodology/Principal Findings

Specimens were collected and morphologically identified during crusies conducted between 2005 and 2008. The standard BARCODE fragment of COI was amplified and bi-directionally sequenced from 577 specimens (mean of 5 specimens/species), and all specimens and sequence data were archived and interrogated using analytical tools available on the Barcode of Life Data System (BOLD; www.barcodinglife.org). Nearly all species exhibited discrete clusters of closely related haplogroups which permitted the discrimination of 95% of the species (i.e. 119/125) examined while cases of shared haplotypes were detected among just three species-pairs. Notably, barcoding aided the identification of a new species of skate, Dipturus argentinensis, permitted the recognition of Genypterus brasiliensis as a valid species and questions the generic assignment of Paralichthys isosceles.

Conclusions/Significance

This study constitutes a significant contribution to the global barcode reference sequence library for fishes and demonstrates the utility of barcoding for regional species identification. As an independent assessment of alpha taxonomy, barcodes provide robust support for most morphologically based taxon concepts and also highlight key areas of taxonomic uncertainty worthy of reappraisal.     

Assessment between pollen seasons in areas with different urbanization level related to local vegetation sources and differences in allergen exposure

Pollen data recorded by a single sampler in any given city often fail to reflect particular events occurring in surrounding areas. This is frequently overlooked when interpreting aerobiological results, and therefore pollen data obtained in urban areas may not necessarily be representative of the situation in more rural areas of the same city. Our purpose is to assess differences between allergenic pollen concentrations recorded in an urban area (Eskulap) and a rural/suburban (Morasko) of the same city from 2005 to 2007. Anova-Manova Scheffe, Spearman correlation and Mixed-design ANOVA whitin-subjects effects tests were applied. The results obtained have showed longer pollen seasons, earlier starts of flowering and later conclusion in the urban area. The participation of arboreal pollen in the pollen fall of both sites had enough significative similarities to determine that is linked to regional conditions, while differences in the atmospheric pollen content of herbaceous plants between sites should be due to local conditions.     

Bioaccumulation of Metals in Cultured Carp (Cyprinus carpio) from Lake Chapala,Mexico

Biological Trace Element Research - Fluoride accumulates and is toxic to bones. Clinical bone lesions occur in a phased manner, being less severe early in the natural course of skeletal fluorosis....     

Predicting changes in dormancy level in natural seed soil banks

The possibility of accurately predicting timing and extent of seedling emergence from natural seed soil banks has long been an objective of both ecologist and agriculturalist. However, as dormancy is a common attribute of many wild seed populations, we should first be able to predict dormancy changes if we intend to predict seedling emergence in the field. In this paper, we discuss the most relevant environmental factors affecting seed dormancy of natural seed soil banks, and present a conceptual framework as an attempt to understand how these factors affect seed-bank dormancy level. Based on this conceptual framework we show approaches that can be used to establish quantitative functional relationship between environmental factors regulating dormancy and changes in the seed-bank dormancy status. Finally, we briefly explain how we can utilize population-based threshold models as a framework to characterize and quantify changes in seed sensitivity to environmental factors as a consequence of dormancy loss and/or induction.     

1-(7-Chloroquinolin-4-yl)-N-(4-Methoxybenzyl)-5-Methyl-1H-1,2, 3-Triazole-4- carboxamide Reduces Aβ Formation and Tau Phosphorylation in Cellular Models of Alzheimer’s Disease

1-(7-Chloroquinolin-4-yl)-N-(4-methoxybenzyl)-5-methyl-1H-1,2,3-triazole-4- carboxamide (QTC-4-MeOBnE) is a new multi-target directed ligand (MTDL) rationally designed to have affinity with β-secretase (BACE), Glycogen Synthase Kinase 3β (GSK3β) and acetylcholinesterase, which are considered promising targets on the development of disease-modifying therapies against Alzheimer’s Disease (AD). Previously, QTC-4-MeOBnE treatment showed beneficial effects in preclinical AD-like models by influencing in vivo neurogenesis, oxidative and inflammatory pathways. However, the biological effect and mechanism of action exerted by QTC-4-MeOBnE in AD cellular models have not been elucidated yet. Hereby we investigate the acute effect of QTC-4-MeOBnE on neuronal cells overexpressing Amyloid Protein Precursor (APP) or human tau protein, the two main features of the AD pathophysiology. When compared to the control group, QTC-4-MeOBnE treatment prevented amyloid beta (Aβ) formation through the downregulation of APP and BACE levels in APPswe-expressing cells. Furthermore, in N2a cells overexpressing human tau, QTC-4-MeOBnE reduced the levels of phosphorylated forms of tau via the modulation of the GSK3β pathway. Taken together, our findings provide new insights into the mechanism of action exerted by QTC-4-MeOBnE in AD cellular models, and further support its potential as an interesting therapeutic strategy against AD.