Novel sulphur-oxidizing bacteria consummate sulphur deficiency in oil seed crop

Archives of Microbiology - Plants absorb sulphate, the oxidized form of elemental sulphur (S°), from soil. Sulphur-oxidizing bacteria play a key role in transformation of sulphur in soil. Oil...     

Efficacy of Polyvalent Bacteriophage P-27/HP to Control Multidrug Resistant <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> Associated with Human Infections

Emergence of multidrug resistant strains has created serious problem for safe eradication of Staphylococcus aureus infections. Therefore, there is an urgent need to develop novel antibacterial agents to control this pathogen. Bacteriophages kill bacteria irrespective of their antibiotic sensitivity and thus they can be used as potent prophylactic/therapeutic agent to treat such infections. Here, we report isolation of broad host range anti-staphylococcal lytic bacteriophage P-27/HP from sewage water. This phage was able to inhibit 17 of 28 (60%) human disease associated S. aureus isolates. In vitro studies revealed its strong lytic efficacy to diminish S. aureus 27/HP population (c.f.u.) by more than 5.0 logs (P < 0.0001) (equivalent to 99.99%) in 3 h at 0.01 MOI. In vivo lytic efficacy analysis showed that a single subcutaneous injection of phage P-27/HP (10⁷ p.f.u.) was sufficient to protect S. aureus 27/HP infected (5 × 10⁸ c.f.u.) mice from bacteremia and subsequent death. A considerable decline of more than 6 logs (99.9%) in splenic S. aureus 27/HP c.f.u. count was noted at the 3 days of phage treatment. In conclusion, our results suggest that phage P-27/HP is polyvalent in nature and has high-lytic potential towards S. aureus, thus, a therapy employing this phage would be efficacious to control S. aureus infections.     

A comparison of the variation in Indian populations of pigeonpea cyst nematode, Heterodera cajani revealed by morphometric and AFLP analysis

The cyst nematode Heterodera cajani is one of the major endemic diseases of pigeonpea, an important legume for food security and protein nutrition in India. It occurs in several pulse crops grown over a range of Indian agro climatic conditions but the extent of its intraspecific variation is inadequately defined. In view of this, 11 populations of Heterodera cajani were analyzed using morphometrics and the results correlated with those obtained from an AFLP approach using 24 primer pair combinations that amplified a total of 1278 AFLP markers. The cluster solution from this binary data indicated similarities for five populations that differed from those suggested by morphometrics. The differences obtained could not be related to geographic distance between populations. The data suggests that recent and long distance dispersal has occurred whose causes need to be defined to restrict further field introductions. Four AFLP primer pairs clustered the populations similarly to that generated using all 24 primer pairs. This simplified approach may provide a rapid basis for discriminating populations for their future management and help to check further distribution in agricultural trade. It may also have potential to determine differences in populations that relate to host range or virulence to resistance genes.     

Inhibition of basal FGF receptor signaling by dimeric Grb2

Receptor tyrosine kinase activity is known to occur in the absence of extracellular stimuli. Importantly, this "background" level of receptor phosphorylation is insufficient to effect a downstream response, suggesting that strict controls are present and prohibit full activation. Here a mechanism is described in which control of FGFR2 activation is provided by the adaptor protein Grb2. Dimeric Grb2 binds to the C termini of two FGFR2 molecules. This heterotetramer is capable of a low-level receptor transphosphorylation, but C-terminal phosphorylation and recruitment of signaling proteins are sterically hindered. Upon stimulation, FGFR2 phosphorylates tyrosine residues on Grb2, promoting dissociation from the receptor and allowing full activation of downstream signaling. These observations establish a role for Grb2 as an active regulator of RTK signaling.     

Site localization of membrane-bound proteins on whole cell level using atomic force microscopy

This study presents molecular recognition method, which is based on specific force measurements between modified AFM (atomic force microscopy) tip and mammalian cell. The presented method allows recognition of specific cell surface proteins and receptor sites by nanometer accuracy level. Here we demonstrate specific recognition of membrane-bound Osteopontin (OPN) sites on preosteogenic cell membrane. By merging specific force detection map of the proteins and topography image of the cell, we create a new image (recognition image), which demonstrates the exact locations of the proteins relative to the cell membrane. The recognition results indicate the strong affinity between the modified tip and the target molecules, therefore, it enables the use of an AFM as a remarkable nanoscale tracking tool on the whole cell level.     

Cell-based screening for membranal and cytoplasmatic markers using dielectric spectroscopy

Dielectric spectroscopy (DS) of living biological cells is based on the analysis of the complex dielectric permittivity of cells suspended in a physiological medium. It provides knowledge on the polarization–relaxation response of cells to external electric field as function of the excitation frequency. This response is strongly affected by both structural and molecular properties of cells and therefore, can reveal rare insights on cell physiology and behaviour. This study demonstrates the mapping potential of DS after cytoplasmatic and membranal markers for cell-based screening analysis. The effect of membrane permittivity and cytoplasm conductivity was examined using tagged MBA and MDCK cell lines respectively. Comparing the permittivity spectra of tagged and native cell lines reveals clear differences between the analyzed suspensions. In addition, differences on the matching dielectric properties of cells were obtained. Those findings support the high distinction resolution and sensitivity of DS after fine molecular and cellular changes, and hence, highlight the high potential of DS as non invasive screening tool in cell biology research.     

Route-dependent stereoselective pharmacokinetics of tramadol and its active O-demethylated metabolite in rats

The effects of route of administration on the stereoselective pharmacokinetics of tramadol (T) and its active metabolite (M1) were studied in rats. A single 20 mg/kg dose of racemic T was administered through intravenous, intraperitoneal, or oral route to different groups of rats, and blood and urine samples were collected. Samples were analyzed using chiral chromatography, and pharmacokinetic parameters (mean +/- SD) were estimated by noncompartmental methods. Following intravenous injection, there was no stereoselectivity in the pharmacokinetics of T. Both enantiomers showed clearance values (62.5 +/- 27.2 and 64.4 +/- 39.0 ml/min/kg for (+)- and (-)-T, respectively) that were equal or higher than the reported liver blood flow in rats. Similar to T, the area under the plasma concentration-time curves (AUCs) of M1 did not exhibit stereoselectivity after intravenous administration of the parent drug. However, the systemic availability of (+)-T was significantly (P < 0.05) higher than that of its antipode following intraperitoneal (0.527 +/- 0.240 vs. 0.373 +/- 0.189) and oral (0.307 +/- 0.136 vs. 0.159 +/- 0.115) administrations. The AUC of the M1 enantiomers, on the other hand, remained mostly nonstereoselective regardless of the route of administration. Pharmacokinetic analysis indicated that the stereoselectivity in the pharmacokinetics of oral T is due to stereoselective first pass metabolism in the liver and, possibly, in the gastrointestinal tract. The direction and extent of stereoselectivity in the pharmacokinetics of T and M1 in rats were in agreement with those previously reported in humans, suggesting that the rat may be a suitable model for enantioselective studies of T pharmacokinetics.     

Optimization of culture conditions for glucose oxidase production by a Penicillium chrysogenum SRT 19 strain

The enzyme glucose oxidase (GOD) has been used for a variety of biotechnological applications in food and pharmaceutical industries. In this study, the optimization of extracellular GOD production was carried out in a Penicillium chrysogenum SRT 19 strain isolated from contaminated and decaying cheese samples. Maximum GOD production was attained at pH 6 and 20°C in fermentation broth after 72 h of incubation. The effects of metal ions and sugars were screened for the induction of higher GOD production. The results revealed that glucose and lactose give the highest production of enzyme (0.670 and 0.552 U/mL, respectively) as compared with other sugars (sucrose, cellulose, mannitol and fructose). Out of the seven metal ions studied, CaCO₃ (1.123 U/mL) and FeSO₄ (0.822 U/mL) act as modulators, while MgSO₄ (0.535 U/mL), CuSO₄ (0.498 U/mL), HgCl₂ (0.476 U/mL), ZnSO₄ (0.457 U/mL) and BaSO₄ (0.422 U/mL) yield lower production. The study therefore suggests that a strain of P. chrysogenum SRT 19 can be used as a new strain for GOD production.     

Small ubiquitin-related modifier ligase activity of Mms21 is required for maintenance of chromosome integrity during the unperturbed mitotic cell division cycle in Saccharomyces cerevisiae

The SUMO ligase activity of Mms21/Nse2, a conserved member of the Smc5/6 complex, is required for resisting extrinsically induced genotoxic stress. We report that the Mms21 SUMO ligase activity is also required during the unchallenged mitotic cell cycle in Saccharomyces cerevisiae. SUMO ligase-defective cells were slow growing and spontaneously incurred DNA damage. These cells required caffeine-sensitive Mec1 kinase-dependent checkpoint signaling for survival even in the absence of extrinsically induced genotoxic stress. SUMO ligase-defective cells were sensitive to replication stress and displayed synthetic growth defects with DNA damage checkpoint-defective mutants such as mec1, rad9, and rad24. MMS21 SUMO ligase and mediator of replication checkpoint 1 gene (MRC1) were epistatic with respect to hydroxyurea-induced replication stress or methyl methanesulfonate-induced DNA damage sensitivity. Subjecting Mms21 SUMO ligase-deficient cells to transient replication stress resulted in enhancement of cell cycle progression defects such as mitotic delay and accumulation of hyperploid cells. Consistent with the spontaneous activation of the DNA damage checkpoint pathway observed in the Mms21-mediated sumoylation-deficient cells, enhanced frequency of chromosome breakage and loss was detected in these mutant cells. A mutation in the conserved cysteine 221 that is engaged in coordination of the zinc ion in Loop 2 of the Mms21 SPL-RING E3 ligase catalytic domain resulted in strong replication stress sensitivity and also conferred slow growth and Mec1 dependence to unchallenged mitotically dividing cells. Our findings establish Mms21-mediated sumoylation as a determinant of cell cycle progression and maintenance of chromosome integrity during the unperturbed mitotic cell division cycle in budding yeast.