Characterization of a Phosphate Solubilizing and Antagonistic Strain of Pseudomonas putida (B0) Isolated from a Sub-Alpine Location in the Indian Central Himalaya

The morphological, biochemical, and physiological characteristics of a phosphate solubilizing and antagonistic bacterial strain, designated as B0, isolated from a sub-alpine Himalayan forest site have been described. The isolate is gram negative, rod shaped, 0.8 x 1.6 microm in size, and psychrotrophic in nature that could grow from 0 to 35 degrees C (optimum temp. 25 degrees C). It exhibited tolerance to a wide pH range (3-12; optimum 8.0) and salt concentration up to 4% (w/v). Although it was sensitive to kanamycin, gentamicin, and streptomycin (<10 microg mL(-1)), it showed resistance to higher concentrations of ampicillin, penicillin, and carbenicillin (>1000 microg mL(-1)). The isolate showed maximum similarity with Pseudomonas putida based on 16S rRNA analysis. It solubilized tricalcium phosphate under in vitro conditions. The phosphate solubilization was estimated along a temperature range (4-28 degrees C), and maximum activity (247 microg mL(-1)) was recorded at 21 degrees C after 15 days of incubation. The phosphate solubilizing activity coincided with a concomitant decrease in pH of the medium. The isolate also exhibited antifungal activity against phytopathogenic fungi in Petri dish assays and produced chitinase, ss-l,3-glucanase, salicylic acid, siderophore, and hydrogen cyanide. The plant growth promotion and antifungal properties were demonstrated through a maize-based bioassay under greenhouse conditions. Although the bacterial inoculation was found to result in significant increment in plant biomass, it stimulated bacterial and suppressed fungal counts in the rhizosphere. The present study is important with respect to enumerating microbial diversity of the colder regions as well as understanding the potential biotechnological applications of native microbes.     

Elevation in Plasma Abeta42 in Geriatric Depression: A Pilot Study

Elevated plasma amyloid beta 1–42 (Aβ42) level has been linked to increased risk for incident AD in cognitively-intact elderly. However, plasma Aβ levels in individuals with late-life depression (LLMD), especially those with a late age of onset of first depressive episode, who are at a particularly increased risk for Alzheimer’s disease, have not been studied. We compared plasma Aβ in 47 elderly with LLMD with 35 controls and examined its relationships to age of onset of first depressive episode, antidepressant treatment (paroxetine or nortriptyline), and indices of platelet activation (platelet factor 4 and beta-thromboglobulin) and brain abnormalities. Results indicated that plasma Aβ42 levels and the Aβ42/40 ratio were elevated in the LLMD group relative to controls in the overall group analyses and in the age- and gender-matched groups. MRI data indicated that higher Aβ42/40 ratio was associated with greater severity of total white matter hyperintensity burden in LLMD. Plasma Aβ levels in LLMD were not influenced by age of onset of first depressive episode or antidepressant treatment and were not related to indices of platelet activation. Our preliminary results suggest that increased plasma Aβ42 and Aβ42/40 ratio are present in geriatric depression, and future studies should be done to confirm these findings and to determine their relationship to cognitive decline and brain abnormalities associated with LLMD.Presented at the 43rd Annual Meeting, American College of Neuropsychopharmacology, San Juan, Puerto Rico, December 12–16, 2004.     

Allocrine modulation of feeding behavior by the Sex Peptide of Drosophila

Mating elicits a dramatic reprogramming of female behavior in numerous insect species. In Drosophila, this postmating response (PMR) comprises increased egg-laying rate and reduced sexual receptivity and is controlled by the products of the male accessory glands, a family of approximately 80 small peptides transferred in the male seminal fluid . Here, we show that copulation strongly stimulates female food intake. Remarkably, this change is abolished if the males lack a single, small seminal protein, the Sex Peptide (SP). Ectopic expression of SP in virgin females mimics the effect of mating on feeding behavior, demonstrating that SP is the main agent controlling this behavioral paradigm. Our observations identify enhanced feeding behavior as a novel component of the Drosophila PMR and suggest that SP represents a molecular link between energy acquisition and reproductive investment.     

Thermodynamics of unfolding of an integral membrane protein in mixed micelles

Quantitative studies of membrane protein folding and unfolding can be difficult because of difficulties with efficient refolding as well as a pronounced propensity to aggregate. However, mixed micelles, consisting of the anionic detergent sodium dodecyl sulfate and the nonionic detergent dodecyl maltoside facilitate reversible and quantitative unfolding and refolding. The 4-transmembrane helix protein DsbB from the inner membrane of Escherichia coli unfolds in mixed micelles according to a three-state mechanism involving an unfolding intermediate I. The temperature dependence of the kinetics of this reaction between 15 degrees and 45 degrees C supports that unfolding from I to the denatured state D is accompanied by a significant decrease in heat capacity. For water-soluble proteins, the heat capacity increases upon unfolding, and this is generally interpreted as the increased binding of water to the protein as it unfolds, exposing more surface area. The decrease in DsbB's heat capacity upon unfolding is confirmed by independent thermal scans. The decrease in heat capacity is not an artifact of the use of mixed micelles, since the water soluble protein S6 shows conventional heat-capacity changes in detergent. We speculate that it reflects the binding of SDS to parts of DsbB that are solvent-exposed in the native DM-bound state. This implies that the periplasmic loops of DsbB are relatively unstructured. This anomalous thermodynamic behavior has not been observed for beta-barrel membrane proteins, probably because they do not bind SDS so extensively. Thus the thermodynamic behavior of membrane proteins appears to be intimately connected to their detergent-binding properties.     

Structure–activity relationship (SAR) of parthenin analogues with pro-apoptotic activity: Development of novel anti-cancer leads

Analogues of parthenin were synthesized by substitutions at different reaction centres to establish a structure–activity relationship (SAR). Some of the molecules have displayed significant cytotoxicity in human cervical carcinoma (HeLa) and human myeloid leukemia (HL-60) cells. A few of the compounds also induced apoptosis in HL-60 cells measured in terms of sub-Go/G1 DNA fraction. Also one of the lead molecules has been shown to be the inhibitor of both telomerase and topoisomerase-II.     

Semisynthetic latrunculin B analogs: Studies of actin docking support a proposed mechanism for latrunculin bioactivity

Latrunculins are unique macrolides containing a thiazolidinone moiety. Latrunculins A, B and T and 16-epi-latrunculin B were isolated from the Red Sea sponge Negombata magnifica. N-Alkylated, O-methylated analogs of latrunculin B were synthesized and biological evaluation was performed for antifungal and antiprotozoal activity. The natural latrunculins showed significant bioactivity, while the semisynthetic analogs did not. Docking studies of these analogs into the X-ray crystal structure of G-actin showed that, in comparison with latrunculins A and B, N-alkylated latrunculins did not dock satisfactorily. This suggests that the analogs do not fit well into the active site of G-actin due to steric clashes and provides an explanation for the absence of bioactivity.     

Coherent ontogenic dynamics of geraniol acetyltransferase activity and geranyl acetate concentration in flowers and leaves of aroma grass Cymbopogon martinii var. Motia

We have investigated the correlation between the concentration of geranyl acetate (GA) and acetyl CoA: geraniol acetyltransferase (GAAT) activity in palamarosa (Cymbopogon martini var. Motia) inflorescence and leaves at their different physiological stages. The results on GA concentration and the GAAT activity have been expressed on per gram fresh weight, per spikelet pair or leaf and per unit area of the phylloplane also incase of leaf. The percentage of geranyl acetate and geraniol in the volatile oil has also been considered. GA concentration was found to be highest in unopened floral spikelets and on the decline in fully open spikelets matching the trend of GAAT activity. Similarly, highest concentration of GA and maximum GAAT activity were found in leaves at mid-stage of development (stage II). The regression analysis curve between GA concentration (mg gFw⁻¹) and GAAT activity (IU 10⁻³ gFw⁻¹) gave an estimate of correlation coefficient (at 95% confidence) value of 0.79 for flowers and 0.92 for leaf. The results suggest that volatile ester (like geranyl acetate) synthesis in foliage and flowers of the aroma oil plant is controlled by the existent catalytic levels GAAT rather than the availability of geraniol. The study also indicates that the GAAT to be a good target to over-express for improvement of oil quality in terms of GA linked to fruit-fresh olfactory note of the oil.     

Low-spin, mononuclear, Fe(III) complexes with P,N donor hemilabile ligands: A combined experimental and theoretical study

Two new mononuclear Fe(III) complexes, [FeCl₃{PPh₂(p-C₆H₄NMe₂)-P}₃](1) (PPh₂(p-C₆H₄NMe₂): 4-(dimethylamino)phenyldiphenylphosphine) and [FeCl₃(PPh₂py-P)(PPh₂py-P,N)] (2) (PPh₂py: diphenyl(2-pyridyl)phosphine) were synthesized by reacting anhydrous FeCl₃ with respective ligand in acetonitrile solution under refluxing condition. Both the complexes were characterized by elemental analysis, FAB-Mass, FTIR, UV-Vis, ESR, Cyclic Voltammetry and magnetic measurement. The FAB mass spectra of complexes 1 and 2 show molecular ion peak at m/z 1078 [M]⁺ and m/z 687 [M−1]⁺, respectively, indicating mononuclear nature of the complexes. UV-Vis spectra of the complexes were consistent with low-spin, octahedral geometry. The variable temperature magnetic susceptibility measurement (73-323 K) of these complexes is also consistent with the paramagnetic nature of the complexes with a ground state spin S = ½. The Fe(III) centers of these two complexes remain low-spin, both at room temperature and liquid nitrogen temperature, was also indicated by the ESR analysis. Cyclic Voltammetry of both the complexes show an irreversible oxidation wave attributed to Fe³⁺ → Fe⁴⁺ + e⁻ along with the peak for ligand oxidation. Theoretical calculations (B3LYP) of the complexes show that for complex 1, a trans geometry of the two phosphorous atoms and for complex 2, a mer,cis structures are the most favored geometrical isomer. TDDFT calculations were performed to interpret the observed bands in the UV-Visible spectra.     

Information processing and signal integration in bacterial quorum sensing

Bacteria communicate using secreted chemical signaling molecules called autoinducers in a process known as quorum sensing. The quorum‐sensing network of the marine bacterium Vibrio harveyi uses three autoinducers, each known to encode distinct ecological information. Yet how cells integrate and interpret the information contained within these three autoinducer signals remains a mystery. Here, we develop a new framework for analyzing signal integration on the basis of information theory and use it to analyze quorum sensing in V. harveyi. We quantify how much the cells can learn about individual autoinducers and explain the experimentally observed input–output relation of the V. harveyi quorum‐sensing circuit. Our results suggest that the need to limit interference between input signals places strong constraints on the architecture of bacterial signal‐integration networks, and that bacteria probably have evolved active strategies for minimizing this interference. Here, we analyze two such strategies: manipulation of autoinducer production and feedback on receptor number ratios.     

Can human papillomavirus DNA testing of self-collected vaginal samples compare with physician-collected cervical samples and cytology for cervical cancer screening in developing countries?

Background: To determine human papillomavirus (HPV) types by polymerase chain reaction (PCR)-reverse line blot assay and examine the concordance between HPV by Hybrid Capture 2 (HC2) and PCR on self-collected vaginal and physician-collected cervical samples and cytology. Methods: This was a cross-sectional study of 546 sexually active women aged ≥30 years with persistent vaginal discharge, intermenstrual or postcoital bleeding or an unhealthy cervix. Participants self-collected vaginal samples (HPV-S) and physicians collected cervical samples for conventional Pap smear and HPV DNA (HPV-P) testing and performed colposcopy, with directed biopsy, if indicated. HPV testing and genotyping was done by HC2 and PCR reverse line blot assay. Concordance between HC2 and PCR results of self- and physician-collected samples was determined using a Kappa statistic (κ) and Chi-square test. Results: Complete data were available for 512 sets with 98% of women providing a satisfactory self-sample. PCR detected oncogenic HPV in 12.3% of self- and 13.0% of physician-collected samples. Overall, there was 93.8% agreement between physician-collected and self-samples (κ = 76.31%, 95% confidence interval [CI]: 64.97–82.29%, p = 0.04)—complete concordance in 473 cases (57 positive, 416 negative), partial concordance in seven pairs and discordance in 32 pairs. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of self-sampling for detection of cervical intraepithelial neoplasia (CIN)2+ disease were 82.5%, 93.6%, 52.4% and 98.4%, respectively; for physician-sampling they were 87.5%, 93.2%, 52.2% and 98.9%, respectively; and for cytology they were 77.5%, 87.3%, 34.1% and 97.9%, respectively. Concordance between HC2 and PCR was 90.9% for self-samples (κ = 63.7%, 95% CI: 55.2–72.2%) and 95.3% for physician-collected samples (κ = 80.4%, 95% CI: 71.8–89.0%). Conclusions: Self-HPV sampling compares favourably with physician-sampling and cytology. A rapid, affordable, HPV self-test kit can be used as the primary method of cervical cancer screening in low-resource situations.