Sunflower Nitrate Reductase: Purification and Characterization

A single isoform, NADH: nitrate reductase (NR), was purified 500 folds from sunflower leaves by affinity chromatography on Blue Sepharose CL-6B. Purified NR had a pH optima of 7.25 and a molecular weight of 210 kD. In SDS-PAGE, two bands of 47 and 56 kD were obtained. NADH: ferric citrate reductase activity was copurified with NR with a specific activity of 2. The Vmax of NADH: ferric citrate reductase was 8.69 units mg^-1 protein and the apparent Km for ferric citrate was 0.435 mM.     

Multilocus sequence analysis of Fusarium pseudograminearum reveals a single phylogenetic species

Fusarium pseudograminearum causes crown rot of wheat in Australia and most other wheat growing regions, but its evolutionary history is largely unknown. We demonstrate for the first time that F. pseudograminearum is a single phylogenetic species without consistent lineage development across genes. Isolates of F. pseudograminearum, F. graminearum sensu lato, and F. cerealis, were collected from four countries and four single copy, nuclear genes were partially sequenced, aligned with previously published sequences of these and related species, and analysed by maximum parsimony and Bayesian inference. Evolutionary divergence varied between genes, with high phylogenetic incongruence occurring between the gene genealogies. The absence of geographic differentiation between isolates indicates that the introduction of new fungal strains to a region has the potential to introduce new pathogenic and toxigenic genes into the native population through sexual recombination.     

Serodiagnosis of Tuberculosis in Asian Elephants (Elephas maximus) in Southern India: A Latent Class Analysis

Background

Mycobacterium tuberculosis, a causative agent of chronic tuberculosis disease, is widespread among some animal species too. There is paucity of information on the distribution, prevalence and true disease status of tuberculosis in Asian elephants (Elephas maximus). The aim of this study was to estimate the sensitivity and specificity of serological tests to diagnose M. tuberculosis infection in captive elephants in southern India while simultaneously estimating sero-prevalence.

Methodology/Principal Findings

Health assessment of 600 elephants was carried out and their sera screened with a commercially available rapid serum test. Trunk wash culture of select rapid serum test positive animals yielded no animal positive for M. tuberculosis isolation. Under Indian field conditions where the true disease status is unknown, we used a latent class model to estimate the diagnostic characteristics of an existing (rapid serum test) and new (four in-house ELISA) tests. One hundred and seventy nine sera were randomly selected for screening in the five tests. Diagnostic sensitivities of the four ELISAs were 91.3–97.6% (95% Credible Interval (CI): 74.8–99.9) and diagnostic specificity were 89.6–98.5% (95% CI: 79.4–99.9) based on the model we assumed. We estimate that 53.6% (95% CI: 44.6–62.8) of the samples tested were free from infection with M. tuberculosis and 15.9% (97.5% CI: 9.8 - to 24.0) tested positive on all five tests.

Conclusions/Significance

Our results provide evidence for high prevalence of asymptomatic M. tuberculosis infection in Asian elephants in a captive Indian setting. Further validation of these tests would be important in formulating area-specific effective surveillance and control measures.     

Store-independent activation of Orai1 by SPCA2 in mammary tumors

Ca(2+) is an essential and ubiquitous second messenger. Changes in cytosolic Ca(2+) trigger events critical for tumorigenesis, such as cellular motility, proliferation, and apoptosis. We show that an isoform of Secretory Pathway Ca(2+)-ATPase, SPCA2, is upregulated in breast cancer-derived cells and human breast tumors, and suppression of SPCA2 attenuates basal Ca(2+) levels and tumorigenicity. Contrary to its conventional role in Golgi Ca(2+) sequestration, expression of SPCA2 increased Ca(2+) influx by a mechanism dependent on the store-operated Ca(2+) channel Orai1. Unexpectedly, SPCA2-Orai1 signaling was independent of ER Ca(2+) stores or STIM1 and STIM2 sensors and uncoupled from Ca(2+)-ATPase activity of SPCA2. Binding of the SPCA2 amino terminus to Orai1 enabled access of its carboxyl terminus to Orai1 and activation of Ca(2+) influx. Our findings reveal a signaling pathway in which the Orai1-SPCA2 complex elicits constitutive store-independent Ca(2+) signaling that promotes tumorigenesis.     

Density‐dependence in common tree species in a tropical dry forest in Mudumalai,southern India

Abstract. Density‐dependence in tree population dynamics has seldom been examined in dry tropical forests. Using long‐term data from a large permanent plot, this study examined 16 common species in a dry tropical forest in southern India for density‐dependence. Employing quadrat‐based analyses, correlations of mortality, recruitment and population change with tree densities were examined. Mortality in 1–10 cm diameter trees was largely negatively correlated with conspecific density, whereas mortality in > 10 cm diameter trees was positively correlated. Mortality was, however, largely unaffected by the basal area and abundance of heterospecific trees. Recruitment was poor in most species, but in Lagerstroemia microcarpa (Lythraceae), Tectona grandis (Verbenaceae) and Cassia fistula (Fabaceae), species that recruited well, strong negative correlations of recruitment with conspecific basal area and abundance were found. In a few other species that could be tested, recruitment was again negatively correlated with conspecific density. In Lagerstroemia, recruitment was positively correlated with the basal area and abundance of heterospecific trees, but these correlations were non‐significant in other species. Similarly, although the rates of population change were negatively correlated with conspecific density they were positive when dry‐season ground fires occurred in the plot. Thus, the observed positive density‐dependence in large‐tree mortality and the negative density‐dependence in recruitment in many species were such that could potentially regulate tree populations. However, repeated fires influenced density‐dependence in the rates of population change in a way that could promote a few common species in the tree community.     

Impact of tuberculosis on serum leptin levels in patients with HIV infection

AIM: Tuberculosis (TB) and human immunodeficiency virus (HIV) are classical wasting diseases accompanied by immunosuppression. As leptin is involved in the weight regulation and cellular immunity, we investigated the role of leptin levels in the co-infection of HIV and TB (HIV-TB). METHODS: The study group consists of the patients with asymptomatic HIV infection (n = 20), patients with HIV-TB co-infection (n = 20) and healthy control subjects (n = 20). Serum leptin levels and the concentrations of IFN-gamma, TNF-alpha, IL-12 and IL-4 cytokines were measured by ELISA before the start of the treatment. CD4+ T-cell counts were determined in patients with HIV and HIV-TB by flow cytometry. Body mass index (BMI) of the study subjects was calculated. RESULTS: Serum leptin levels and BMI were significantly lower in the patients with HIV-TB than control and HIV subjects. Multivariate regression analysis showed that serum leptin concentration was significantly dependent on BMI and sex but not on age and the disease groups. The leptin levels did not correlate either with CD4+ T-cell counts or with any of the serum cytokines in HIV and HIV-TB patients. CONCLUSION: Thus our finding suggests that the leptin concentrations were strongly associated with BMI and gender but not with the disease state or with the circulating cytokine levels.