Evaluation of Microbial Biomass and Activity in Different Soils Exposed to Increasing Level of Arsenic Pollution: A Laboratory Study

Soil contamination with arsenic is a widespread phenomenon in many parts of the world and it is well known that it may affect the soil microbial community. A laboratory experiment was performed to evaluate the acute toxicity effect of different As concentrations (0, 0.1, 1.0, 10, 100, and 200 mg/kg) on soil biological parameters like microbial biomass carbon (MBC), active microbial biomass carbon (AMBC), basal soil respiration (BSR), fluorescein diacetate hydrolase activity (FDA), and dehydrogenase activity (DHA) under three different soil types (Inceptisol, Vertisol, and Entisol). Soil enzyme activities, microbial biomass, and respiration were significantly decreased by arsenic exposure. The soil metabolic quotient increased with increasing As concentration, the maximum being observed for Entisol followed by Vertisol and Inceptisol. Except for soil enzyme activities, the majority of which started to decrease after the addition of 10 mg/kg arsenic, all other parameters decreased at arsenic dose ≥0.1 mg/kg. The decrease of AMBC/MBC ratio showed that acute arsenic stress affected the active microorganisms more than the dormant component of total microbial biomass. Among the three soils studied, Vertisol was comparatively more tolerant to As exposure in terms of soil enzymes and biomass, followed by Inceptisol and Entisol. MBC has evolved as a distinct parameter in cluster analysis, while some others, such as DHA and AMBC, and FDA and BSR, appeared essentially redundant.     

How to Decide Whether to Move Species Threatened by Climate Change

Introducing species to areas outside their historical range to secure their future under climate change is a controversial strategy for preventing extinction. While the debate over the wisdom of this strategy continues, such introductions are already taking place. Previous frameworks for analysing the decision to introduce have lacked a quantifiable management objective and mathematically rigorous problem formulation. Here we develop the first rigorous quantitative framework for deciding whether or not a particular introduction should go ahead, which species to prioritize for introduction, and where and how to introduce them. It can also be used to compare introduction with alternative management actions, and to prioritise questions for future research. We apply the framework to a case study of tuatara (Sphenodon punctatus) in New Zealand. While simple and accessible, this framework can accommodate uncertainty in predictions and values. It provides essential support for the existing IUCN guidelines by presenting a quantitative process for better decision-making about conservation introductions.     

Impact of Community-Based Lymphedema Management on Perceived Disability among Patients with Lymphatic Filariasis in Orissa State,India

Background

Lymphatic filariasis (LF) infects approximately 120 million people worldwide. As many as 40 million have symptoms of LF disease, including lymphedema, elephantiasis, and hydrocele. India constitutes approximately 45% of the world''s burden of LF. The Indian NGO Church''s Auxiliary for Social Action (CASA) has been conducting a community-based lymphedema management program in Orissa State since 2007 that aims to reduce the morbidity associated with lymphedema and elephantiasis. The objective of this analysis is to evaluate the effects of this program on lymphedema patients'' perceived disability.

Methodology/Principal Findings

For this prospective cohort study, 370 patients ≥14 years of age, who reported lymphedema lasting more than three months in one or both legs, were recruited from villages in the Bolagarh sub-district, Khurda District, Orissa, India. The World Health Organization Disability Assessment Schedule II was administered to participants at baseline (July, 2009), and then at regular intervals through 24 months (July, 2011), to assess patients'' perceived disability. Disability scores decreased significantly (p<0.0001) from baseline to 24 months. Multivariable analysis using mixed effects modeling found that employment and time in the program were significantly associated with lower disability scores after two years of program involvement. Older age, female gender, the presence of other chronic health conditions, moderate (Stage 3) or advanced (Stage 4–7) lymphedema, reporting an adenolymphangitis (ADL) episode during the previous 30 days, and the presence of inter-digital lesions were associated with higher disability scores. Patients with moderate or advanced lymphedema experienced greater improvements in perceived disability over time. Patients participating in the program for at least 12 months also reported losing 2.5 fewer work days per month (p<0.001) due to their lymphedema, compared to baseline.

Significance

These results indicate that community-based lymphedema management programs can reduce disability and prevent days of work lost. These effects were sustained over a 24 month period.     

Parental care trade‐offs in the inter‐brood phase in Barn Swallows Hirundo rustica

In seasonal environments with limited time and energy resources, double‐brooded birds face trade‐offs in the timing of their two reproductive attempts and in the effort allocated to the first and the second broods. In the Barn Swallow Hirundo rustica a long care period for the first brood enhances the survival of first‐brood chicks, but also delays the start of the second brood, which in turn reduces the survival prospects of second‐brood chicks. Probably as a response to this trade‐off, double‐brooded Barn Swallows reduce the period of post‐fledging care for first‐brood fledglings. By radiotracking whole families, we investigated the determinants of this behaviour and its consequences for the survival of the first‐brood fledglings. The end of the females’ investment in post‐fledging care of the first brood was related to the beginning of egg synthesis for the second clutch. With the start of egg synthesis, females significantly reduced provisioning rates to the first‐brood fledglings to less than one‐fifth of the previous rates, while the proportion of time they spent foraging remained high. Assuming that the females’ foraging success was constant, we conclude that their energy income was allocated to egg production rather than fledgling provision. Males did not compensate for the females’ reduced feeding rates. Thus the start of egg production for the second clutch had a marked effect on the quantity of food received by first‐brood fledglings. In parallel with the changes in parental behaviour and provisioning rates, we observed a marked drop in the daily survival rate of first‐brood chicks. These results support the hypothesis that females face a strong trade‐off in the allocation of energy to subsequent broods. Energy allocation to a second clutch involves a cost in terms of reduced provisioning, and as a result the survival of first‐brood chicks is compromised. This is probably outweighed by the improved success of an early second brood.     

Structure of Transmembrane Domain of Lysosome-associated Membrane Protein Type 2a (LAMP-2A) Reveals Key Features for Substrate Specificity in Chaperone-mediated Autophagy

Chaperone-mediated autophagy (CMA) is a highly regulated cellular process that mediates the degradation of a selective subset of cytosolic proteins in lysosomes. Increasing CMA activity is one way for a cell to respond to stress, and it leads to enhanced turnover of non-critical cytosolic proteins into sources of energy or clearance of unwanted or damaged proteins from the cytosol. The lysosome-associated membrane protein type 2a (LAMP-2A) together with a complex of chaperones and co-chaperones are key regulators of CMA. LAMP-2A is a transmembrane protein component for protein translocation to the lysosome. Here we present a study of the structure and dynamics of the transmembrane domain of human LAMP-2A in n-dodecylphosphocholine micelles by nuclear magnetic resonance (NMR). We showed that LAMP-2A exists as a homotrimer in which the membrane-spanning helices wrap around each other to form a parallel coiled coil conformation, whereas its cytosolic tail is flexible and exposed to the cytosol. This cytosolic tail of LAMP-2A interacts with chaperone Hsc70 and a CMA substrate RNase A with comparable affinity but not with Hsp40 and RNase S peptide. Because the substrates and the chaperone complex can bind at the same time, thus creating a bimodal interaction, we propose that substrate recognition by chaperones and targeting to the lysosomal membrane by LAMP-2A are coupled. This can increase substrate affinity and specificity as well as prevent substrate aggregation, assist in the unfolding of the substrate, and promote the formation of the higher order complex of LAMP-2A required for translocation.     

Molecular modeling and docking characterization of CzR1, a CC-NBS-LRR R-gene from Curcuma zedoaria Loeb. that confers resistance to Pythium aphanidermatum

Plant NBS-LRR R-genes recognizes several pathogen associated molecular patterns (PAMPs) and limit pathogen infection through a multifaceted defense response. CzR1, a coiled-coil-nucleotide-binding-site-leucine-rich repeat R-gene isolated from Curcuma zedoaria L exhibit constitutive resistance to different strains of P. aphanidermatum. Majority of the necrotrophic oomycetes are characterized by the presence of carbohydrate PAMPs β-glucans in their cell walls which intercat with R-genes. In the present study, we predicted the 3D (three dimensional) structure of CzR1 based on homology modeling using the homology module of Prime through the Maestro interface of Schrodinger package ver 2.5. The docking investigation of CzR1 with β-glucan using the Glide software suggests that six amino acid residues, Ser186, Glu187, Ser263, Asp264, Asp355 and Tyr425 act as catalytic residues and are involved in hydrogen bonding with ligand β-(1,3)-D-Glucan. The calculated distance between the carboxylic oxygen atoms of Glu187–Asp355 pair is well within the distance of 5Å suggesting a positive glucanase activity of CzR1. Elucidation of these molecular characteristics will help in in silico screening and understanding the structural basis of ligand binding to CzR1 protein and pave new ways towards a broad spectrum rhizome rot resistance development in the cultivated turmeric.     

Isolation and structural elucidation of a water-soluble polysaccharide (PS-I) of a wild edible mushroom, Termitomyces striatus

A heteropolysaccharide (PS-I), isolated from the hot aqueous extract of an edible mushroom, Termitomyces striatus, is composed of d-glucose, d-galactose, d-mannose and l-fucose in a molar ratio 2:1:1:1. Structural investigation of the native as well as the Smith-degraded polysaccharide was carried out using methylation analysis, periodate oxidation studies and 1D and 2D NMR spectroscopy, and the repeating unit of the polysaccharide is established as follows: [carbohydrate structure: see text]     

A water-insoluble (1-->3)-beta-D-glucan from the alkaline extract of an edible mushroom Termitomyces eurhizus

A water-insoluble glucan, TEINS has been isolated from the hot alkaline extract of an edible mushroom Termitomyces eurhizus. The total carbohydrate content of the polysaccharide fraction was found to be 98.4%, and it was found to contain only glucose as the monosaccharide constituent. On the basis of total acid hydrolysis, a methylation experiment, periodate oxidation and (13)C NMR experiment, the repeating unit of the polysaccharide was established as: -->3)-beta-D-Glcp-(1-->.     

Identification and genetic variation among Hibiscus species (Malvaceae) using RAPD markers

Germplasm identification and characterization is an important link between the conservation and utilization of plant genetic resources. Traditionally, species or cultivars identification has relied on morphological characters like growth habit or floral morphology like flower colour and other characteristics of the plant. Studies were undertaken for identification and determination of genetic variation within the two species of Hibiscus and 16 varieties of Hibiscus rosa-sinensis L. through random amplified polymorphic (RAPD) markers. Primer screening was made by using the DNA of variety "Prolific". Genetic analysis was made by using ten selected decamer primers. A total of 79 distinct DNA fragments ranging from 0.3 to 2.5 kb were amplified by using ten selected random decamer primers. The genetic similarity was evaluated on the basis of presence or absence of bands. The cluster analysis indicated that the 16 varieties and two species formed one cluster. The first major cluster consisted of three varieties and a second major cluster consisted of two species and 13 varieties. The genetic distance was very close within the varieties and also among the species. Thus, these RAPD markers have the potential for identification of species/varieties and characterization of genetic variation within the varieties. This is also helpful in Hibiscus breeding programs and provides a major input into conservation biology.