Occurrence of Salt, pH, and Temperature-tolerant, Phosphate-solubilizing Bacteria in Alkaline Soils

An ecological survey was conducted to characterize 4800 bacterial strains isolated from the root-free soil, rhizosphere, and rhizoplane of Prosopis juliflora growing in alkaline soils. Of the 4800 bacteria, 857 strains were able to solubilize phosphate on plates. The incidence of phosphate-solubilizing bacteria (PSB) in the rhizoplane was highest, followed by rhizosphere and root-free soil. Eighteen bacterial strains out of 857 PSB were able to produce halo at 30°C in a plate assay in the presence of 5% salt (NaCl) and solubilize tricalcium phosphate in National Botanical Research Institute's phosphate growth medium (NBRIP) broth, in the presence of various salts, pHs, and temperatures. Among the various bacteria tested, NBRI4 and NBRI7 did not produced halo in a plate assay at 30°C in the absence of salt. Contrary to indirect measurement of phosphate solubilization by plate assay, the direct measurement of phosphate solubilization in NBRIP broth assay always resulted in reliable results. The phosphate solubilization ability of NBRI4 was higher than in the control in the presence of salts (NaCl, CaCl₂, and KCl) at 30°C. Phosphate solubilization further increased in the presence of salts at 37°C as compared with 30°C. At 37°C, CaCl₂ reduced phosphate solubilization ability of NBRI4 compared with the control. The results indicated the role of calcium salt in the phosphate solubilization ability of NBRI4. Received: 9 March 1999 / Accepted: 16 April 1999     

Rhizosphere competent <Emphasis Type="Italic">Pantoea agglomerans</Emphasis> enhances maize (<Emphasis Type="Italic">Zea mays</Emphasis>) and chickpea (<Emphasis Type="Italic">Cicer arietinum</Emphasis> L.) growth,without altering the rhizosphere functional diversity

Plant growth promoting Pantoea agglomerans NBRISRM (NBRISRM) was able to produce 60.4 μg/ml indole acetic acid and solubilize 77.5 μg/ml tri-calcium phosphate under in vitro conditions. Addition of 2% NaCl (w/v) in the media induced the IAA production and phosphate solubilization by 11% and 7%, respectively. For evaluating the plant growth promotory effect of NBRISRM inoculation a micro plot trial was conducted using maize and chickpea as host plants. The results revealed significant increase in all growth parameters tested in NBRISRM inoculated maize and chickpea plants, which were further confirmed by higher macronutrients (N, P and K) accumulation as compared to un-inoculated controls. Throughout the growing season of maize and chickpea, rhizosphere population of NBRISRM were in the range 10⁷–10⁸ CFU/g soil and competing with 10⁷–10⁹ CFU/g soil with heterogeneous bacterial population. Functional richness, diversity, and evenness were found significantly higher in maize rhizosphere as compared to chickpea, whereas NBRISRM inoculation were not able to change it, in both crops as compared to their un-inoculated control. To the best of our knowledge this is first report where we demonstrated the effect of P. agglomerans strain for improving maize and chickpea growth without altering the functional diversity.     

Schlafen-3 decreases cancer stem cell marker expression and autocrine/juxtacrine signaling in FOLFOX-resistant colon cancer cells

We have previously demonstrated that expression of the novel gene schlafen-3 (Slfn-3) correlates with intestinal epithelial cell differentiation (Patel VB, Yu Y, Das JK, Patel BB, Majumdar AP. Biochem Biophys Res Commun 388: 752-756, 2009). The present investigation was undertaken to examine whether Slfn-3 plays a role in regulating differentiation of FOLFOX-resistant (5-fluorouracil + oxaliplatin) colon cancer cells that are highly enriched in cancer stem cells (CSCs). Transfection of Slfn-3 in FOLFOX-resistant colon cancer HCT-116 cells resulted in increase of alkaline phosphatase activity, a marker of intestinal differentiation. Additionally, Slfn-3 transfection resulted in reduction of mRNA and protein levels of the CSC markers CD44, CD133, CD166, and aldehyde dehydrogenase 1 in both FOLFOX-resistant HCT-116 and HT-29 cells. This was accompanied by decreased formation of tumorosphere/colonosphere (an in vitro model of tumor growth) in stem cell medium and inhibition of expression of the chemotherapeutic drug transporter protein ABCG2. Additionally, Slfn-3 transfection of FOLFOX-resistant HCT-116 and HT-29 cells reduced Hoechst 33342 dye exclusion. Finally, Slfn-3 transfection inhibited the expression of transforming growth factor-α in both FOLFOX-resistant colon cancer cells, but stimulated apoptosis in response to additional FOLFOX treatment. In summary, our data demonstrate that Slfn-3 expression inhibits multiple characteristics of CSC-enriched, FOLFOX-resistant colon cancer cells, including induction of differentiation and reduction in tumorosphere/colonosphere formation, drug transporter activity, and autocrine stimulation of proliferation. Thus Slfn-3 expression may render colon CSCs more susceptible to cancer chemotherapeutics.     

Cleome viscosa, capparidaceae: A weed or a cash crop?

Cleome viscosa, an annual herb locally known as Jakhiya, grows naturally from seed in rainfed agricultural land and abandoned crop fields at altitudes ranging from 500 to 1500 m in scattered pockets of the Garhwal Himalaya. The seeds are mostly used as condiment. This species is a good substitute of cumin (Cuminum cyminum). Traditionally it is also used to cure a variety of diseases. It provides, three times higher yield when maintained by the farmers as a pure crop compared to yield obtained in mixed cropping conditions. With other food commodities, it is exchanged by the traditional farmers of Garhwal with the people of the areas where it does not grow. Because of its increasing demand, it is being sold in the market and is gaining more and more popularity. Until now no systematic attempt has been made to study the ecological significance and economic potential of Cleome viscosa. This paper describes the agronomy, yield, cost-benefit analysis, uses, and ethnobotany of Cleome viscosa. Systematic efforts are needed to promote its cultivation on a larger scale in village community degraded land and in marginal agricultural land where traditional crops grow with difficulty.     

Disordered IL-33/ST2 Activation in Decidualizing Stromal Cells Prolongs Uterine Receptivity in Women with Recurrent Pregnancy Loss

Decidualization renders the endometrium transiently receptive to an implanting blastocyst although the underlying mechanisms remain incompletely understood. Here we show that human endometrial stromal cells (HESCs) rapidly release IL-33, a key regulator of innate immune responses, upon decidualization. In parallel, differentiating HESCs upregulate the IL-33 transmembrane receptor ST2L and other pro-inflammatory mediators before mounting a profound anti-inflammatory response that includes downregulation of ST2L and increased expression of the soluble decoy receptor sST2. We demonstrate that HESCs secrete factors permissive of embryo implantation in mice only during the pro-inflammatory phase of the decidual process. IL-33 knockdown in undifferentiated HESCs was sufficient to abrogate this pro-inflammatory decidual response. Further, sequential activation of the IL-33/ST2L/sST2 axis was disordered in decidualizing HESCs from women with recurrent pregnancy loss. Signals from these cultures prolonged the implantation window but also caused subsequent pregnancy failure in mice. Thus, Il-33/ST2 activation in HESCS drives an autoinflammatory response that controls the temporal expression of receptivity genes. Failure to constrain this response predisposes to miscarriage by allowing out-of-phase implantation in an unsupportive uterine environment.     

Synergistic effect of Pseudomonas putida and Bacillus amyloliquefaciens ameliorates drought stress in chickpea (Cicer arietinum L.)

Two plant growth promoting rhizobacteria (PGPR) Pseudomonas putida NBRIRA and Bacillus amyloliquefaciens NBRISN13 with ability to tolerate abiotic stress along with multiple PGP traits like ACC deaminase activity, minerals solubilisation, hormones production, biofilm formation, siderophore activity were evaluated for their synergistic effect to ameliorate drought stress in chickpea. Earlier we have reported both the strains individually for their PGP attributes and stress amelioration in host plants. The present study explains in detail the possibilities and benefits of utilizing these 2 PGPR in consortium for improving the chickpea growth under control and drought stressed condition. In vitro results clearly demonstrate that both the PGPR strains are compatible to each other and their synergistic growth enhances the PGP attributes. Greenhouse experiments were conducted to evaluate the effect of inoculation of both strains individually and consortia in drought tolerant and sensitive cultivars (BG362 and P1003). The growth parameters were observed significantly higher in consortium as compared to individual PGPR. Colonization of both PGPR in chickpea rhizosphere has been visualized by using gfp labeling. Apart from growth parameters, defense enzymes, soil enzymes and microbial diversity were significantly modulated in individually PGPR and in consortia inoculated plants. Negative effects of drought stress has been ameliorated and apparently seen by higher biomass and reversal of stress indicators in chickpea cultivars treated with PGPR individually or in consortia. Findings from the present study demonstrate that synergistic application has better potential to improve plant growth promotion under drought stress conditions.     

Reciprocity between Regulatory T Cells and Th17 Cells: Relevance to Polarized Immunity in Leprosy

T cell defect is a common feature in lepromatous or borderline lepromatous leprosy (LL/BL) patients in contrast to tuberculoid or borderline tuberculoid type (TT/BT) patients. Tuberculoid leprosy is characterized by strong Th1-type cell response with localized lesions whereas lepromatous leprosy is hallmarked by its selective Mycobacterium leprae specific T cell anergy leading to disseminated and progressive disease. FoxP3+ Regulatory T cells (Treg) which are essential for maintaining peripheral tolerance, preventing autoimmune diseases and limiting chronic inflammatory diseases also dampen proinflammatory T cells that include T helper 17 (Th17) cells. This study is aimed at evaluating the role of Treg cells in influencing other effector T cells and its relationship with the cytokine polarized state in leprosy patients. Peripheral blood mononuclear cells from of BT/TT (n = 15) and BL/LL (n = 15) patients were stimulated with M. leprae antigen (WCL) in presence of golgi transport inhibitor monensin for FACS based intracellular cytokine estimation. The frequency of Treg cells showed >5-fold increase in BL/LL in comparison to BT/TT and healthy contacts. These cells produced suppressive cytokine, IL-10 in BL/LL as opposed to BT/TT (p = 0.0200) indicating their suppressive function. The frequency of Th17 cells (CD4, CD45RO, IL-17) was, however, higher in BT/TT. Significant negative correlation (r = -0.68, P = 0.03) was also found between IL-10 of Treg cells and IL-17+ T cells in BL/LL. Blocking IL-10/TGF-β restored the IL-17+ T cells in BL/LL patients. Simultaneously, presence of Th17 related cytokines (TGF-β, IL-6, IL-17 and IL-23) decreased the number of FoxP3+ Treg cells concomitantly increasing IL-17 producing CD4+ cells in lepromatous leprosy. Higher frequency of Programmed Death-1/PD-1+ Treg cells and its ligand, PDL-1 in antigen presenting cells (APCs) was found in BL/LL patients. Inhibition of this pathway led to rescue of IFN-γ and IL-17 producing T cells. Results indicate that Treg cells are largely responsible for the kind of immunosuppression observed in BL/LL patients. This study also proves that Treg cells are profoundly affected by the cytokine milieu and this property may be utilized for benefit of the host.     

Reducing the allelopathic effect of Partheniumhysterophorus L. on wheat (Triticumaestivum L.) by Pseudomonasputida

The present study evaluates the role of Pseudomonas putida NBRIC19 in alleviating biotic stress of Parthenium hysterophorus (Parthenium) in Triticum aestivum. Due to presence of Parthenium there was 43.76, 53.08 and 78.65% inhibition in root length, shoot length and dry weight of wheat respectively. This inhibition was recovered when P. putida NBRIC19 treatment resulted in 52.29, 28.73 and 76.31% increase in root length, shoot length and dry weight respectively as compared to control. P. putida NBRIC19 was able to form more biofilm under toxic environment of allelochemicals and enhanced expression of stress responsive genes in wheat. Inoculated wheat plants showed lower activity of catalase and ascorbate peroxidase under biotic stress of Parthenium indicating that inoculated plants felt less stress as compared to uninoculated plants. Microbial community structure in bacterized and nonbacterized wheat rhizosphere in presence and absence of Parthenium, was investigated using Biolog. There was significant increase in microbial diversity in P. putida NBRIC19 bacterized wheat rhizosphere. Functional microbial diversity revealed that P. putida NBRIC19 had shifted the microflora in such a manner that utilization of phytotoxic allelochemicals increased to lessen its toxic effect and finally it resulted in better growth of wheat in presence of Parthenium. Principal component analysis showed that microbial community function in nonbacterized wheat rhizosphere in presence (WPC) and absence (WC) of Parthenium is totally different from each other but due to P. putida NBRIC19 treatment there was close clustering of WPT and WT indicating a total shift in microbial community structure.