Salicylic acid-induced salinity tolerance in corn grown under NaCl stress

Effects of salicylic acid on some physiological and biochemical characteristics of maize ( Zea mays L.) seedlings under NaCl stress were studied. Pre-soaking treatments of NaCl (0, 50, 100 and 200 mM) were given to maize seeds in the presence as well as in the absence of 0.5 mM salicylic acid. Two-week-old maize seedlings exhibited significant decrease in dry weight, root length, shoot length and leaf area on 6 h exposure of 100 and 200 mM NaCl stress. Photosynthetic pigments and NR activity in leaves decreased sharply with increasing stress levels. Both proline content and lipid peroxidation (measured in terms of MDA) levels increased significantly under saline conditions. However, seedlings pretreated with 0.5 mM salicylic acid along with the salinity levels showed enhancement in growth parameters, photosynthetic pigments, NR activity while, free proline and MDA levels decreased. The results showed that salt-induced deleterious effects in maize seedlings were significantly encountered by the pretreatment of salicylic acid. It is concluded that 0.5 mM salicylic acid improves the adaptabilities of maize plants to NaCl stress.     

Evidence of a humoral immune response against the prokaryotic expressed N-terminal autoprotease (N<Superscript>pro</Superscript>) protein of bovine viral diarrhoea virus

Bovine viral diarrhoea virus (BVDV) is an economically important pathogen of cattle and sheep belonging to the genus Pestivirus of the family Flaviviridae. Although the BVDV non-structural N-terminal protease (N^pro) acts as an interferon antagonist and subverts the host innate immunity, little is known about its immunogenicity. Hence, we expressed a recombinant BVDV N^pro-His fusion protein (28 kDa) in E. coli and determined the humoral immune response generated by it in rabbits. The antigenicity of the N^pro protein was confirmed by western blot using anti-BVDV hyperimmune cattle, sheep and goat serum, and anti-N^pro rabbit serum. When rabbits were immunized with the N^pro protein, a humoral immune response was evident by 4 weeks and persisted till 10 weeks post immunization as detected by ELISA and western blot. Despite N^pro-specific antibodies remaining undetectable in 80 serum samples from BVDV-infected sheep and goats, BVDV hyperimmune sera along with some of the field cattle, sheep and goat sera with high BVDV neutralizing antibody titres were found positive for N^pro antibodies. Our results provide evidence that despite the low immunogenicity of the BVDV N^pro protein, a humoral immune response is induced in cattle, sheep and goats only with repeated BVDV exposure.     

DDOST mutations identified by whole-exome sequencing are implicated in congenital disorders of glycosylation

Congenital disorders of glycosylation (CDG) are inherited autosomal-recessive diseases that impair N-glycosylation. Approximately 20% of patients do not survive beyond the age of 5 years old as a result of widespread organ dysfunction. Although most patients receive a CDG diagnosis based on abnormal glycosylation of transferrin, this test cannot provide a genetic diagnosis; indeed, many patients with abnormal transferrin do not have mutations in any known CDG genes. Here, we combined biochemical analysis with whole-exome sequencing (WES) to identify the genetic defect in an untyped CDG patient, and we found a 22 bp deletion and a missense mutation in DDOST, whose product is a component of the oligosaccharyltransferase complex that transfers the glycan chain from a lipid carrier to nascent proteins in the endoplasmic reticulum lumen. Biochemical analysis with three biomarkers revealed that N-glycosylation was decreased in the patient's fibroblasts. Complementation with wild-type-DDOST cDNA in patient fibroblasts restored glycosylation, indicating that the mutations were pathological. Our results highlight the power of combining WES and biochemical studies, including a glyco-complementation system, for identifying and confirming the defective gene in an untyped CDG patient. This approach will be very useful for uncovering other types of CDG as well.     

Mutations in the glycosylphosphatidylinositol gene PIGL cause CHIME syndrome

CHIME syndrome is characterized by colobomas, heart defects, ichthyosiform dermatosis, mental retardation (intellectual disability), and ear anomalies, including conductive hearing loss. Whole-exome sequencing on five previously reported cases identified PIGL, the de-N-acetylase required for glycosylphosphatidylinositol (GPI) anchor formation, as a strong candidate. Furthermore, cell lines derived from these cases had significantly reduced levels of the two GPI anchor markers, CD59 and a GPI-binding toxin, aerolysin (FLAER), confirming the pathogenicity of the mutations.     

Detection of Salt Marsh Vegetation Stress and Recovery after the Deepwater Horizon Oil Spill in Barataria Bay,Gulf of Mexico Using AVIRIS Data

The British Petroleum Deepwater Horizon Oil Spill in the Gulf of Mexico was the biggest oil spill in US history. To assess the impact of the oil spill on the saltmarsh plant community, we examined Advanced Visible Infrared Imaging Spectrometer (AVIRIS) data flown over Barataria Bay, Louisiana in September 2010 and August 2011. Oil contamination was mapped using oil absorption features in pixel spectra and used to examine impact of oil along the oiled shorelines. Results showed that vegetation stress was restricted to the tidal zone extending 14 m inland from the shoreline in September 2010. Four indexes of plant stress and three indexes of canopy water content all consistently showed that stress was highest in pixels next to the shoreline and decreased with increasing distance from the shoreline. Index values along the oiled shoreline were significantly lower than those along the oil-free shoreline. Regression of index values with respect to distance from oil showed that in 2011, index values were no longer correlated with proximity to oil suggesting that the marsh was on its way to recovery. Change detection between the two dates showed that areas denuded of vegetation after the oil impact experienced varying degrees of re-vegetation in the following year. This recovery was poorest in the first three pixels adjacent to the shoreline. This study illustrates the usefulness of high spatial resolution airborne imaging spectroscopy to map actual locations where oil from the spill reached the shore and then to assess its impacts on the plant community. We demonstrate that post-oiling trends in terms of plant health and mortality could be detected and monitored, including recovery of these saltmarsh meadows one year after the oil spill.     

Performance of a Limiting-Antigen Avidity Enzyme Immunoassay for Cross-Sectional Estimation of HIV Incidence in the United States

Background

A limiting antigen avidity enzyme immunoassay (HIV-1 LAg-Avidity assay) was recently developed for cross-sectional HIV incidence estimation. We evaluated the performance of the LAg-Avidity assay alone and in multi-assay algorithms (MAAs) that included other biomarkers.

Methods and Findings

Performance of testing algorithms was evaluated using 2,282 samples from individuals in the United States collected 1 month to >8 years after HIV seroconversion. The capacity of selected testing algorithms to accurately estimate incidence was evaluated in three longitudinal cohorts. When used in a single-assay format, the LAg-Avidity assay classified some individuals infected >5 years as assay positive and failed to provide reliable incidence estimates in cohorts that included individuals with long-term infections. We evaluated >500,000 testing algorithms, that included the LAg-Avidity assay alone and MAAs with other biomarkers (BED capture immunoassay [BED-CEIA], BioRad-Avidity assay, HIV viral load, CD4 cell count), varying the assays and assay cutoffs. We identified an optimized 2-assay MAA that included the LAg-Avidity and BioRad-Avidity assays, and an optimized 4-assay MAA that included those assays, as well as HIV viral load and CD4 cell count. The two optimized MAAs classified all 845 samples from individuals infected >5 years as MAA negative and estimated incidence within a year of sample collection. These two MAAs produced incidence estimates that were consistent with those from longitudinal follow-up of cohorts. A comparison of the laboratory assay costs of the MAAs was also performed, and we found that the costs associated with the optimal two assay MAA were substantially less than with the four assay MAA.

Conclusions

The LAg-Avidity assay did not perform well in a single-assay format, regardless of the assay cutoff. MAAs that include the LAg-Avidity and BioRad-Avidity assays, with or without viral load and CD4 cell count, provide accurate incidence estimates.     

Biosynthesis of extracellular and intracellular gold nanoparticles by Aspergillus fumigatus and A. flavus

Green chemistry is a boon for the development of safe, stable and ecofriendly nanostructures using biological tools. The present study was carried out to explore the potential of selected fungal strains for biosynthesis of intra- and extracellular gold nanostructures. Out of the seven cultures, two fungal strains (SBS-3 and SBS-7) were selected on the basis of development of dark pink colour in cell free supernatant and fungal beads, respectively indicative of extra- and intracellular gold nanoparticles production. Both biomass associated and cell free gold nanoparticles were characterized using X-ray diffractogram (XRD) analysis and transmission electron microscopy (TEM). XRD analysis confirmed crystalline, face-centered cubic lattice of metallic gold nanoparticles along with average crystallite size. A marginal difference in average crystallite size of extracellular (17.76 nm) and intracellular (26 and 22 nm) Au-nanostructures was observed using Scherrer equation. In TEM, a variety of shapes (triangles, spherical, hexagonal) were observed in both extra- and intracellular nanoparticles. 18S rRNA gene sequence analysis by multiple sequence alignment (BLAST) indicated 99 % homology of SBS-3 to Aspergillus fumigatus with 99 % alignment coverage and 98 % homology of SBS-7 to Aspergillus flavus with 98 % alignment coverage respectively. Native-PAGE and activity staining further confirmed enzyme linked synthesis of gold nanoparticles.     

UV-absorbing bacteria in coral mucus and their response to simulated temperature elevations

Reef-building corals encompass various strategies to defend against harmful ultraviolet (UV) radiation. Coral mucus contains UV-absorbing compounds and has rich prokaryotic diversity associated with it. In this study, we isolated and characterized the UV-absorbing bacteria from the mucus of the corals Porites lutea and Acropora hyacinthus during the pre-summer and summer seasons. A total of 17 UV-absorbing bacteria were isolated and sequenced. The UV-absorbing bacteria showed UV absorption at wavelengths ranging from λ _max = 333 nm to λ _min = 208 nm. Analysis of the DNA sequences revealed that the majority of the UV-absorbing bacteria belonged to the family Firmicutes and the remaining belonged to the family Proteobacteria (class Gammaproteobacteria). Comparison of the sequences with the curated database yielded four distinct bacterial groups belonging to the genus Bacillus, Staphylococcus, Salinicoccus and Vibrio. The absorption peaks for the UV-absorbing bacteria shifted to the UV-A range (320–400 nm) when they were incubated at higher temperatures. Deciphering the complex relationship between corals and their associated bacteria will help us to understand their adaptive strategies to various stresses.     

The tyrosine kinase CSK associates with FLT3 and c-Kit receptors and regulates downstream signaling

Type III receptor tyrosine kinases (RTKs), FLT3 and c-Kit play important roles in a variety of cellular processes. A number of SH2-domain containing proteins interact with FLT3 and c-Kit and regulate downstream signaling. The SH2-domain containing non-receptor protein tyrosine kinase CSK is mainly studied in the context of regulating Src family kinases. Here we present an additional role of this kinase in RTK signaling. We show that CSK interacts with FLT3 and c-Kit in a phosphorylation dependent manner. This interaction is facilitated through the SH2-domain of CSK. Under basal conditions CSK is mainly localized throughout the cytosolic compartment but upon ligand stimulation it is recruited to the inner side of cell membrane. CSK association did not alter receptor ubiquitination or phosphorylation but disrupted downstream signaling. Selective depletion of CSK using siRNA, or inhibition with CSK inhibitor, led to increased phosphorylation of Akt and Erk, but not p38, upon FLT3 ligand (FL) stimulation. Stem cell factor (SCF)-mediated Akt and Erk activation was also elevated by CSK inhibition. However, siRNA mediated CSK knockdown increased SCF stimulated Akt phosphorylation but decreased Erk phosphorylation. CSK depletion also significantly increased both FL- and SCF-induced SHC, Gab2 and SHP2 phosphorylation. Furthermore, CSK depletion contributed to oncogenic FLT3- and c-Kit-mediated cell proliferation, but not to cell survival. Thus, the results indicate that CSK association with type III RTKs, FLT3 and c-Kit can have differential impact on receptor downstream signaling.     

Micro RNAs: tiny sequences with enormous potential

The liver plays a central role in glucose homeostasis in the whole-body by responding to environmental factors including nutrients, hormones, and oxygen. In conditions of metabolic overload such as diabetes mellitus and obesity, coordinated regulation between oxygen supply and consumption has been reported to be disrupted and subsequently cause tissue hypoxia, although pathological significance of the disease-related hypoxia remains elusive. To investigate the role of tissue hypoxia in the liver on systemic glucose homeostasis, mice lacking HIF-1α gene, a critical component of a master regulator of hypoxic response, in hepatocytes were exposed to high fat/sucrose diet (HFSD). Exposure to HFSD for 5 weeks elicited liver hypoxia with a transient increase in HIF-1α protein expression in the liver of control mice. Glucose disposal was marginally impaired in control mice when challenged oral glucose tolerance test, but such impairment was enhanced in the mutant mice. This alteration was accompanied by a complete inhibition of glucokinase induction with a significant reduction of hepatic glucose uptake. Mice fed HFSD for 20 weeks exhibited fasting hyperglycemia and glucose intolerance, whereas these metabolic phenotypes deteriorated considerably with severe insulin resistance in skeletal muscles and adipose tissues in the mutant mice. These findings suggest that HIF-1 in hepatocytes plays protective roles against the progression of diabetes mellitus.