Rheology and composition of a multi-utility exopolymer from a desert borne cyanobacterium Anabaena variabilis

The desert cyanobacterium Anabaena variabilis produces an exopolymer during the stationary growth phase in batch culture. Optimal polymer production was observed at pH?10 under phosphorus limitation. Chemical analysis showed it to be composed of 49% carbohydrate and 19% protein. Monosaccharide analysis revealed a heteropolysaccharidic nature with glucose, mannose, and galactose as the main neutral sugars. Infrared (IR) spectrum of the exopolymer showed absorption bands at 1,645 and 1,421?cm^?1 characteristic of C=O in the carboxylate group. Strong band was observed at 1,072?cm^?1 due to C–O–C or C–O–P stretching vibrations. A band at 2,363?cm^?1 corresponding to C–H stretch of protein was also observed. IR spectrum suggested that the exopolymer is nonsulfated. Rheological properties of the polymer showed marked shear thinning non-Newtonian behavior in the concentration range of 0.1–0.4%. However, it appeared to undergo change in the internal structure on shearing thereby exhibiting thixotropic behavior. The polymer possessed 75% flocculating ability vis a vis alum, 71% emulsification of hexadecane, and good thermal stability making it a potent candidate for multiple industrial applications. The exopolymer bound 156?g H₂O g^?1 and exhibited antibacterial activity against Staphylococcus aureus suggesting a potential for application in wound management as well.     

Avian predation on a parasitic fly of cervids during winter: can host‐related cues increase the predation risk?

The deer ked (Lipoptena cervi) is an ectoparasitic fly on cervids that has expanded its distribution rapidly in Northern Europe. However, the regulating biotic factors such as predation remain unknown. The host‐independent pupal stage of the fly lasts for several months. Blackish pupae are visible against snow, especially on the bedding sites of hosts, and are thus exposed to predators. To evaluate the role of predation on the invasion dynamics and evolution of L. cervi, we monitored pupal predation on artificial bedding sites in three geographical areas in Finland during winter. We explored: (1) possible predators; (2) magnitude of predation; and (3) whether predation risk is affected by host‐derived cues. We demonstrate that pupae are predated by a number of tit species. Any reddish brown snow discoloration on bedding sites, indicating heavy infestation of the host, serves as an exploitable cue for avian predators, thereby increasing the risk of pupal predation. The ability of tits to use this host‐derived cue seems to be dependent on the prevalence of L. cervi and the period of invasion history, which suggests that it may be a learned behavioural response. Predation by tits may potentially affect the L. cervi population dynamics locally. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106 , 275–286.     

A Quantitative Study of Olfactory, Non-Olfactory, and Vomeronasal Epithelia in the Nasal Fossa of the Bat Megaderma lyra

In complexity, the mammalian nasal fossa is unparalleled among vertebrates. Although total nasal epithelial surface areas (SA) have been reported for numerous mammals, detailed quantitative reports on individual structures exist for few mammals. Here, we examine mucosal distribution in the nasal fossa of the greater false vampire bat, Megaderma lyra (Megadermatidae, Chiropera). The SA of the left nasal fossa of one adult Megaderma was measured in serial histological sections; the development of the nasal fossa was assessed using three fetal specimens. The nasal fossa of Megaderma has seven ethmoturbinals and multiple smaller interturbinals between them, all bearing olfactory mucosa. Nearly half of the total olfactory SA of the nasal fossa lines these turbinals; the remainder lines recesses and parts of the medial (septal) and lateral walls of the nasal fossa. The maxilloturbinal is diminutive, and the nasoturbinal is absent. Volumetric measurements of the fetal and adult vomeronasal organ suggest age-related reduction. Thirty-five percent of the nasal fossa is lined with olfactory mucosa, within the range reported previously for chiropterans. In Megaderma the frontal recess contributes little to total nasal SA (2% of all olfactory SA). This represents a significant departure in morphology compared to other mammals, including some bats, in which the frontal recess is much larger. The significance of the emphasis in olfactory SA distribution to central or more peripheral (paranasal) spaces could be investigated using a large sample of phylogenetically diverse mammals, such as bats. This study emphasizes the need for more histological detail to further such studies.     

Loss of CCR7 Expression on CD56bright NK Cells Is Associated with a CD56dimCD16+ NK Cell-Like Phenotype and Correlates with HIV Viral Load

NK cells are pivotal sentinels of the innate immune system and distinct subpopulations in peripheral blood have been described. A number of studies addressed HIV-induced alterations of NK cell phenotype and functionality mainly focusing on CD56^dimCD16⁺ and CD56⁻CD16⁺ NK cells. However, the impact of HIV-infection on CD56^bright NK cells is less well understood. Here we report a rise of CD56^bright NK cells in HIV-infected individuals, which lack CCR7-expression and strongly correlate with HIV viral load. CCR7⁻CD56^bright NK cells were characterized by increased cytolytic potential, higher activation states and a more differentiated phenotype. These cells thus acquired a number of features of CD56^dimCD16⁺ NK cells. Furthermore, CD56^bright NK cells from HIV patients exhibited higher degranulation levels compared to uninfected individuals. Thus, chronic HIV-infection is associated with a phenotypic and functional shift of CD56^bright NK cells, which provides a novel aspect of HIV-associated pathogenesis within the NK cell compartment.     

Interleukin-8 is the single most up-regulated gene in whole genome profiling of <Emphasis Type="Italic">H. pylori</Emphasis> exposed gastric epithelial cells

Background  

The association between Helicobacter pylori infection and upper gastrointestinal disease is well established. However, only a small fraction of H. pylori carriers develop disease, and there are great geographical differences in disease penetrance. The explanation to this enigma lies in the interaction between the bacterium and the host. H. pylori Outer Membrane Phospholipase A (OMPLA) has been suggested to play a role in the virulence of this bacterium. The aim of this study was to profile the most significant cellular pathways and biological processes affected in gastric epithelial cells during 24 h of H. pylori exposure, and to study the inflammatory response to OMPLA⁺ and OMPLA^- H. pylori variants.     

Urinary metabolomic phenotyping of nickel induced acute toxicity in rat: an NMR spectroscopy approach

The metabolomic approach has been widely used in toxicology to investigate mechanisms of toxicity. To understand the mammalian system??s response to nickel exposure, we analysed the NiCl₂ induced metabolomic changes in urine of rats using ¹H nuclear magnetic resonance (¹H NMR) spectroscopy together with clinically relevant biochemical parameters. Male Sprague?CDawley rats were administered intraperitoneally with NiCl₂ at doses of 4, 10 and 20?mg/kg body weight. Urine samples were collected at 8, 16, 24, 72, 96 and 120?h post treatment. The metabolomic profile of rat urine showed prominent changes in citrate, dimethylamine, creatinine, choline, trimethylamine oxide (TMAO), phenyl alanine and hippurate at all doses. Principal component analysis of urine ¹H NMR spectra demonstrated the dose and time dependent development of toxicity. The metabolomic time trajectory, based on pattern recognition analysis of ¹H NMR spectra of urine, illustrated clear separation of pre and post treatments (temporal). Only animals treated with a low dose of NiCl₂ returned to normal physiology. The ¹H NMR spectral data correlated well with the clinically relevant nephrotoxic biomarkers. The urinary metabolomic phenotyping for NiCl₂ induced nephrotoxicity was defined according to the predictive ability of the known metabolite biomarkers, creatinine, citrate and TMAO. The current approach demonstrates that metabolomics, one of the most important platform in system biology, may be a promising tool for identifying and characterizing biochemical responses to toxicity.     

Genetic characterization of Chikungunya virus from New Delhi reveal emergence of a new molecular signature in Indian isolates

ABSTRACT: BACKGROUND: Chikungunya (CHIK) is currently endemic in South and Central India and exist as co-infections with dengue in Northern India. In 2010, New Delhi witnessed an outbreak of CHIK in the months October-December. This was the first incidence of a dominant CHIK outbreak in Delhi and prompted us to characterize the Delhi virus strains. We have also investigated the evolution of CHIK spread in India. FINDINGS: Clinical samples were subjected to RT-PCR to detect CHIK viral RNA. The PCR amplified products were sequenced and the resulting sequences were genetically analyzed. Phylogenetic analysis based on partial sequences of the structural proteins E1 and E2 revealed that the viruses in the latest outbreak exhibited ECSA lineage. Two novel mutations, E1 K211E and E2 V264A were observed in all Delhi isolates. In addition, CHIKV sequences from eight states in India were analyzed along with Delhi sequences to map the genetic diversity of CHIKV within the country. Estimates of average evolutionary divergence within states showed varying divergence among the sequences both within the states and between the states. We identified distinct molecular signatures of the different genotypes of CHIKV revealing emergence of a new signature in the New Delhi clade. Statistical analyses and construction of evolutionary path of the virus within the country revealed gradual spread of one specific strain all over the country. CONCLUSION: This study has identified unique mutations in the E1 and E2 genes and has revealed the presence of ancestral CHIKV population with maximum diversity circulating in Maharashtra. The study has further revealed the trend of CHIK spread in India since its first report in 1963 and its subsequent reappearance in 2005.     

An insecticidal GroEL protein with chitin binding activity from Xenorhabdus nematophila

Xenorhabdus nematophila secretes insecticidal proteins to kill its larval prey. We have isolated an approximately 58-kDa GroEL homolog, secreted in the culture medium through outer membrane vesicles. The protein was orally insecticidal to the major crop pest Helicoverpa armigera with an LC50 of approximately 3.6 microg/g diet. For optimal insecticidal activity all three domains of the protein, apical, intermediate, and equatorial, were necessary. The apical domain alone was able to bind to the larval gut membranes and manifest low level insecticidal activity. At equimolar concentrations, the apical domain contained approximately one-third and the apical-intermediate domain approximately one-half bioactivity of that of the full-length protein. Interaction of the protein with the larval gut membrane was specifically inhibited by N-acetylglucosamine and chito-oligosaccharides. Treatment of the larval gut membranes with chitinase abolished protein binding. Based on the three-dimensional structural model, mutational analysis demonstrated that surface-exposed residues Thr-347 and Ser-356 in the apical domain were crucial for both binding to the gut epithelium and insecticidal activity. Double mutant T347A,S356A was 80% less toxic (p < 0.001) than the wild type protein. The GroEL homolog showed alpha-chitin binding activity with Kd approximately 0.64 microm and Bmax approximately 4.68 micromol/g chitin. The variation in chitin binding activity of the mutant proteins was in good agreement with membrane binding characteristics and insecticidal activity. The less toxic double mutant XnGroEL showed an approximately 8-fold increase of Kd in chitin binding assay. Our results demonstrate that X. nematophila secretes an insecticidal GroEL protein with chitin binding activity.     

Arbuscular mycorrhizal (AM) technology for the conservation of <Emphasis Type="Italic">Curculigo orchioides</Emphasis> Gaertn.: an endangered medicinal herb

Curculigo orchioides Gaertn. (family Hypoxidaceae) is an endangered anticarcinogenic and aphrodisiac herb, native of India. This study reports the effect of three arbuscular mycorrhizal (AM) fungal inocula on post-transplanting performance of ‘in vitro’ raised C. orchioides plantlets. The three AM fungal inocula consisted of two monospecific cultures of Glomus geosporum and G. microcarpum and one crude consortium of AM fungal spores isolated from rhizosphere soil of C. orchioides growing in natural habitat. Complete plantlets of C. orchioides were raised by direct organogenesis of leaf explants on half strength Murashige and Skoog’s medium devoid of any growth hormone. C. orchioides plantlets responded significantly different to all three mycorrhizal treatments. Mycorrhization enhanced the survival rate of C. orchioides plantlets to 100%. The inoculated plantlets fared significantly better than the uninoculated ones in terms of biomass production and number of leaves and roots per plant. Mycorrhizal plantlets exhibited higher concentrations of photosynthetic pigments as well as minerals P, Mg, Cu, Zn, Mn and Fe in both shoots and roots. Among the three inocula tested, plantlets inoculated with the mixed consortium of AM fungi consistently performed better in terms of the parameters evaluated. The study suggests use of mixed consortium of AM fungi over monospecific cultures for the sustainable cultivation and conservation of endangered medicinal plant: Curculigo orchioides.