Admixture Mapping Scans Identify a Locus Affecting Retinal Vascular Caliber in Hypertensive African Americans: the Atherosclerosis Risk in Communities (ARIC) Study

Retinal vascular caliber provides information about the structure and health of the microvascular system and is associated with cardiovascular and cerebrovascular diseases. Compared to European Americans, African Americans tend to have wider retinal arteriolar and venular caliber, even after controlling for cardiovascular risk factors. This has suggested the hypothesis that differences in genetic background may contribute to racial/ethnic differences in retinal vascular caliber. Using 1,365 ancestry-informative SNPs, we estimated the percentage of African ancestry (PAA) and conducted genome-wide admixture mapping scans in 1,737 African Americans from the Atherosclerosis Risk in Communities (ARIC) study. Central retinal artery equivalent (CRAE) and central retinal vein equivalent (CRVE) representing summary measures of retinal arteriolar and venular caliber, respectively, were measured from retinal photographs. PAA was significantly correlated with CRVE (ρ = 0.071, P = 0.003), but not CRAE (ρ = 0.032, P = 0.182). Using admixture mapping, we did not detect significant admixture association with either CRAE (genome-wide score = −0.73) or CRVE (genome-wide score = −0.69). An a priori subgroup analysis among hypertensive individuals detected a genome-wide significant association of CRVE with greater African ancestry at chromosome 6p21.1 (genome-wide score = 2.31, locus-specific LOD = 5.47). Each additional copy of an African ancestral allele at the 6p21.1 peak was associated with an average increase in CRVE of 6.14 µm in the hypertensives, but had no significant effects in the non-hypertensives (P for heterogeneity <0.001). Further mapping in the 6p21.1 region may uncover novel genetic variants affecting retinal vascular caliber and further insights into the interaction between genetic effects of the microvascular system and hypertension.     

Promising Biological Indicator of Heavy Metal Pollution: Bioluminescent Bacterial Strains Isolated and Characterized from Marine Niches of Goa,India

In present study, several marine water samples collected from the North Goa Beaches, India for isolation of luminescent bacterial species. Isolates obtained labelled as DP1-5 and AB1-6. Molecular characterization including identification of a microbial culture using 16S rRNA gene based molecular technique and phylogenetic analysis confirmed that DP3 & AB1 isolates were Vibrio harveyi. All of the isolates demonstrated multiple metal resistances in terms of growth, with altered luminescence with variable metal concentration. Present investigations were an attempt towards exploring and reporting an updated diversity of bioluminescent bacterial species from various sites around the Goa, India which would be explored in future for constructing luminescence based biosensor for efficiently monitoring the level of hazardous metals in the environment.

Electronic supplementary material

The online version of this article (doi:10.1007/s12088-015-0531-y) contains supplementary material, which is available to authorized users.     

Novel N-terminal mutation of human apolipoprotein A-I reduces self-association and impairs LCAT activation

We have identified a novel mutation in apoA-I (serine 36 to alanine; S36A) in a human subject with severe hypoalphalipoproteinemia. The mutation is located in the N-terminal region of the protein, which has been implicated in several functions, including lipid binding and lecithin:cholesterol acyltransferase (LCAT) activity. In the present study, the S36A protein was produced recombinantly and characterized both structurally and functionally. While the helical content of the mutant protein was lower compared with wild-type (WT) apoA-I, it retained its helical character. The protein stability, measured as the resistance to guanidine-induced denaturation, decreased significantly. Interestingly, native gel electrophoresis, cross-linking, and sedimentation equilibrium analysis showed that the S36A mutant was primarily present as a monomer, notably different from the WT protein, which showed considerable oligomeric forms. Although the ability of S36A apoA-I to solubilize phosphatidylcholine vesicles and bind to lipoprotein surfaces was not altered, a significantly impaired LCAT activation compared with the WT protein was observed. These results implicate a region around S36 in apoA-I self-association, independent of the intact C terminus. Furthermore, the region around S36 in the N-terminus of human apoA-I is necessary for LCAT activation.     

Nitric oxide inhibits wound collagen synthesis

Nitric oxide (NO) is a messenger molecule which regulates many physiological functions like immunity, vascular tone and serves as a neurotransmitter. Although it is known to participate in healing process, its role in collagen synthesis is not clear. Therefore, the present investigation was done to study the role of NO in wound collagen synthesis. Rats received full thickness, circular (8 mm), transdermal wounds which were treated with NO releaser, sodium nitroprusside (SNP, 0.001 100 M) topically for 5 days. Wound collagen content estimated in terms of hydroxyproline (HP) and confirmed histochemically was decreased significantly by all SNP doses. L-Arginine, a substrate for nitric oxide synthase (NOS) when applied topically decreased collagen content of the wounded tissues. N-Nitro-L-arginine methyl ester (L-NAME), a competitive inhibitor of NOS, increased wound collagen content significantly as compared to untreated and SNP treated animal wounds when administered intraperitoneally at the doses 3, 10 and 30 mg/kg. Furthermore, histological findings also demonstrated laying down of thick collagen bundles and proliferation of fibroblasts together with prominent angiogenesis in L-NAME treated wound tissues as compared to untreated and SNP treated tissues. N-nitro-D-arginine methyl ester, an inactive isomer, was found to have no effect on wound collagen levels. When L-arginine was administered in L-NAME pretreated rats, it significantly elevated wound HP content. The results indicate that NO plays an important role in regulating the collagen biosynthesis in skin model of a healing wound.     

Antibody immobilisation on fibre optic TIRF sensors

A study of antibody immobilisation techniques on quartz and fibre optic surfaces for immunosensors has been carried out. Methods of covalent antibody immobilisation which have not previously been applied to optical fibres were investigated, and compared with classical methods found in the literature. Preliminary experiments on covalent immobilisation methods on planar quartz surfaces were conducted to enable us to choose the most suitable protein immobilisation technique for sensor applications. The immobilisation studies were directed in particular towards obtaining a high density of binding sites for the analyte of interest. Two of the most promising methods, antibody immobilisation on surfaces coated with dextran based hydrogel and F(ab')-SH fragments bound to silanised glass, which resulted in surface densities of active sites of above 0.45 pmol/cm2, were selected for further experiments on a fibre optic total internal reflection fluorescence immunosensor and gave satisfactory responses to changes in analyte concentrations of the order of 10(-8) M. The efficiency of polar organic solvents, such as dimethylsulfoxide, in dissociating the antigen-antibody complex and hence to regenerate the immunosensor surface was also evaluated.     

Asbestos induces mitochondrial DNA damage and dysfunction linked to the development of apoptosis

To test the hypothesis that asbestos-mediated cell injury is mediated through an oxidant-dependent mitochondrial pathway, isolated mesothelial cells were examined for mitochondrial DNA damage as determined by quantitative PCR. Mitochondrial DNA damage occurred at fourfold lower concentrations of crocidolite asbestos compared with concentrations required for nuclear DNA damage. DNA damage by asbestos was preceded by oxidant stress as shown by confocal scanning laser microscopy using MitoTracker Green FM and the oxidant probe Redox Sensor Red CC-1. These events were associated with dose-related decreases in steady-state mRNA levels of cytochrome c oxidase, subunit 3 (COIII), and NADH dehydrogenase 5. Subsequently, dose-dependent decreases in formazan production, an indication of mitochondrial dysfunction, increased mRNA expression of pro- and antiapoptotic genes, and increased numbers of apoptotic cells were observed in asbestos-exposed mesothelial cells. The possible contribution of mitochondrial-derived pathways to asbestos-induced apoptosis was confirmed by its significant reduction after pretreatment of cells with a caspase-9 inhibitor. Apoptosis was decreased in the presence of catalase. Last, use of HeLa cells transfected with a mitochondrial transport sequence targeting the human DNA repair enzyme 8-oxoguanine DNA glycosylase to mitochondria demonstrated that asbestos-induced apoptosis was ameliorated with increased cell survival. Studies collectively indicate that mitochondria are initial targets of asbestos-induced DNA damage and apoptosis via an oxidant-related mechanism.     

MazF-induced Growth Inhibition and Persister Generation in Escherichia coli

Toxin-antitoxin systems are ubiquitous in nature and present on the chromosomes of both bacteria and archaea. MazEF is a type II toxin-antitoxin system present on the chromosome of Escherichia coli and other bacteria. Whether MazEF is involved in programmed cell death or reversible growth inhibition and bacterial persistence is a matter of debate. In the present work the role of MazF in bacterial physiology was studied by using an inactive, active-site mutant of MazF, E24A, to activate WT MazF expression from its own promoter. The ectopic expression of E24A MazF in a strain containing WT mazEF resulted in reversible growth arrest. Normal growth resumed on inhibiting the expression of E24A MazF. MazF-mediated growth arrest resulted in an increase in survival of bacterial cells during antibiotic stress. This was studied by activation of mazEF either by overexpression of an inactive, active-site mutant or pre-exposure to a sublethal dose of antibiotic. The MazF-mediated persistence phenotype was found to be independent of RecA and dependent on the presence of the ClpP and Lon proteases. This study confirms the role of MazEF in reversible growth inhibition and persistence.     

Role of a cytotoxic-T-lymphocyte epitope-defined, alternative gag open reading frame in the pathogenesis of a murine retrovirus-induced immunodeficiency syndrome

LP-BM5 murine leukemia virus-infected C57BL/6 mice develop profound immunodeficiency and B-cell lymphomas. The LP-BM5 complex contains a mixture of defective (BM5def) and replication-competent helper viruses among which BM5def is the primary causative agent of disease. The BM5def primary open reading frame (ORF1) encodes the single gag precursor protein (Pr60gag). Our lab has recently demonstrated that a novel immunodominant cytotoxic-T-lymphocyte (CTL) epitope (SYNTGRFPPL) is expressed from a +1-nucleotide translational open reading frame of BM5def during the course of normal retrovirus expression. The SYNTGRFPPL CTL epitope may be generated from either of two initiation methionines present, ORF2a or ORF2b, located downstream of the ORF1 initiation site. This study investigates the role(s) of the alternative ORF2-derived gag protein(s) of BM5def in viral pathogenesis. We have examined the disease-inducing capabilities of mutant viruses in which the translational potential of either the initiating ORF2a or ORF2b AUG has been disrupted. Although these mutated viruses are capable of wild-type ORF1 expression, they are unable to induce disease. Our data strongly suggest the existence of a novel ORF2 product(s) that is required for LP-BM5-induced pathogenesis and have potentially broad implications for other retroviral diseases.     

Prophylactic Efficacy of <Emphasis Type="Italic">Coriandrum sativum</Emphasis> (Coriander) on Testis of Lead-Exposed Mice

Lead poisoning is a worldwide health problem, and its treatment is under investigation. The aim of this study was to access the efficacy of Coriandrum sativum (coriander) in reducing lead-induced changes in mice testis. Animal exposed to lead nitrate showed significant decrease in testicular SOD, CAT, GSH, total protein, and tissue lead level. This was accompanied by simultaneous increase in the activities of LPO, AST, ALT, ACP, ALP, and cholesterol level. Serum testosterone level and sperm density were suppressed in lead-treated group compared with the control. These influences of lead were prevented by concurrent daily administration of C. sativum extracts to some extent. Treating albino mice with lead-induced various histological changes in the testis and treatment with coriander led to an improvement in the histological testis picture. The results thus led us to conclude that administration of C. sativum significantly protects against lead-induced oxidative stress. Further work need to be done to isolate and purify the active principle involved in the antioxidant activity of this plant.