Surfactant mediated enhanced biodegradation of hexachlorocyclohexane (HCH) isomers by Sphingomonas sp. NM05

Environmental biodegradation of several chlorinated pesticides is limited by their low solubility and sorption to soil surfaces. To mitigate this problem we quantified the effect of three biosurfactant viz., rhamnolipid, sophorolipid and trehalose-containing lipid on the dissolution, bioavailability, and biodegradation of HCH-isomers in liquid culture and in contaminated soil. The effect of biosurfactants was evaluated through the critical micelle concentration (CMC) value as determined for each isomer. The surfactant increased the solubilization of HCH isomers by 3-9 folds with rhamnolipid and sophorolipid being more effective and showing maximum solubilization of HCH isomers at 40 μg/mL, compared to trehalose-containing lipid showing peak solubilization at 60 μg/mL. The degradation of HCH isomers by Sphingomonas sp. NM05 in surfactant-amended liquid mineral salts medium showed 30% enhancement in 2 days as compared to degradation in 10 days in the absence of surfactant. HCH-spiked soil slurry incubated with surfactant also showed around 30-50% enhanced degradation of HCH which was comparable to the corresponding batch culture experiments. Among the three surfactants, sophorolipid offered highest solubilization and enhanced degradation of HCH isomers both in liquid medium and soil culture. The results of this study suggest the effectiveness of surfactants in improving HCH degradation by increased bioaccessibility.     

Intra- and Intergenomic variation of Ploidy and Clonality characterize <Emphasis Type="Italic">Phytophthora capsici</Emphasis> on <Emphasis Type="Italic">Capsicum</Emphasis> sp. in Taiwan

Phytophthora capsici is a devastating disease of pepper (Capsicum sp.) in Taiwan causing complete loss of commercial fields. The objective of this study was to characterize genetic diversity for 38 newly collected isolates and three historical isolates. Analysis of data includes whole genome sequence for two new isolates and for two isolates collected previously in 1987 and 1995. In addition, 63 single nucleotide polymorphism loci were genotyped using targeted-sequencing, revealing 27 unique genotypes. Genotypes fell into three genetic groups: two of the groups contain 90% (n = 33) of the 2016 isolates, are triploid (or higher), are exclusively the A2 mating type and appear to be two distinct clonal lineages. The isolates from 2016 that grouped with the historical isolates are diploid and the A1 mating type. Whole genome sequence revealed that ploidy varies by linkage group, and it appears the A2 clonal lineages may have switched mating type due to increased ploidy. Most of the isolates were recently race-typed on a set of differential C. annuum, and although there was no direct correlation between virulence and ploidy, many of the triploid isolates were less virulent as compared to the historical diploid isolates. The implications for breeding resistant pepper and conducting population analyses are discussed.     

Enterococci in river Ganga surface waters: Propensity of species distribution, dissemination of antimicrobial-resistance and virulence-markers among species along landscape

Background  

Surface waters quality has declined in developing countries due to rapid industrialization and population growth. The microbiological quality of river Ganga, a life-sustaining surface water resource for large population of northern India, is adversely affected by several point and non-point sources of pollution. Further, untreated surface waters are consumed for drinking and various household tasks in India making the public vulnerable to water-borne diseases and outbreaks. Enterococci, the 'indicator' of water quality, correlates best with the incidence of gastrointestinal diseases as well as prevalence of other pathogenic microorganisms. Therefore, this study aims to determine the distribution of species diversity, dissemination of antimicrobial-resistance and virulence-markers in enterococci with respect to rural-urban landscape along river Ganga in northern India.     

Antagonists of anaphase-promoting complex (APC)-2-cell cycle and apoptosis regulatory protein (CARP)-1 interaction are novel regulators of cell growth and apoptosis

CARP-1/CCAR1, a perinuclear phosphoprotein, is a regulator of cell growth and apoptosis signaling. Although CARP-1 is a regulator of chemotherapy-dependent apoptosis, it is also a part of the NF-κB proteome and a co-activator of steroid/thyroid nuclear receptors as well as β-catenin signaling. Our yeast two-hybrid screen revealed CARP-1 binding with the anaphase-promoting complex/cyclosome E3 ubiquitin ligase component APC-2 protein. CARP-1 also binds with anaphase-promoting complex/cyclosome co-activators Cdc20 and Cdh1. Following mapping of the minimal epitopes involved in CARP-1 binding with APC-2, a fluorescence polarization assay was established that indicated a dissociation constant (K(d)) of 480 nm for CARP-1/APC-2 binding. Fluorescence polarization assay-based high throughput screening of a chemical library yielded several small molecule antagonists of CARP-1/APC-2 binding, termed CARP-1 functional mimetics. CFM-4 (1(2-chlorobenzyl)-5'-phenyl-3'H-spiro[indoline-3,2'-[1,3,4]thiadiazol]-2-one), a lead compound, binds with and stimulates CARP-1 expression. CFM-4 prevents CARP-1 binding with APC-2, causes G(2)M cell cycle arrest, and induces apoptosis with an IC(50) range of 10-15 μm. Apoptosis signaling by CFM-4 involves activation of caspase-8 and -9 and caspase-mediated ubiquitin-proteasome pathway-independent loss of cyclin B1 and Cdc20 proteins. Depletion of CARP-1, however, interferes with CFM-4-dependent cell growth inhibition, activation of caspases, and apoptosis. Because CFM-4 also suppresses growth of drug-resistant human breast cancer cells without affecting the growth of human breast epithelial MCF-10A cells, elevating CARP-1 by CFM-4 and consequent apoptosis could in principle be exploited to further elucidate, and perhaps effectively target, often deregulated cell cycle pathways in pathological conditions, including cancer.     

Of Least Concern? Range Extension by Rhesus Macaques (<Emphasis Type="BoldItalic">Macaca mulatta</Emphasis>) Threatens Long-Term Survival of Bonnet Macaques (<Emphasis Type="BoldItalic">M. radiata</Emphasis>) in Peninsular India

Rhesus and bonnet macaques are the 2 most common and widely distributed of the 8 macaque species of India. Rhesus macaques are widely distributed across southern and southeastern Asia, whereas bonnet macaques are restricted to peninsular India. We studied the current distributional limits of the 2 species, examined patterns of their coexistence in the interspecific border zones, and evaluated losses in the distributional range of bonnet macaques over the last 3 decades. Our results indicate that whereas rhesus macaques have extended their geographical range into the southern peninsula, bonnet macaques have been displaced from many areas within their former distributional range. The southern and the northern distributional limits for rhesus and bonnet macaques, respectively, currently run parallel to each other in the western part of the country, are separated by a large gap in central India, and converge on the eastern coast of the peninsula to form a distribution overlap zone. This overlap region is characterized by the presence of mixed-species troops, with pure troops of both species sometimes occurring even in close proximity to one another. The range extension of rhesus macaque—a natural process in some areas and a direct consequence of introduction by humans in other regions—poses grave implications for the endemic and declining populations of bonnet macaques in southern India.     

Isolation and characterization of a chromium-resistant bacterium Serratia sp. Cr-10 from a chromate-contaminated site

A novel bacterium, Cr-10, was isolated from a chromium-contaminated site and capable of removing toxic chromium species from solution by reducing hexavalent chromium to an insoluble precipitate. Sequence analysis of 16S rRNA gene of strain Cr-10 showed that it was most closely related to Serratia rubidaea JCM 1240^T (97.68%). Physiological and chemotaxonomic data also supported that strain Cr-10 was identified as Serratia sp., a genus which was never specially reported chromate-resistant before. Serratia sp., Cr-10 was tolerant to a concentration of 1,500 mg Cr(VI) L⁻¹, which was the highest level reported until now. The optimum pH and temperature for reduction of Cr(VI) by Serratia sp. Cr-10 were found to be 7.0 and 37 °C, respectively. The Cr(VI) reduction was significantly influenced by additional carbon sources, and among them fructose and lactose offered maximum reduction, with a rate of 0.28 and 0.25 mg Cr(VI) L⁻¹ h⁻¹, respectively. The cell-free extracts and filtrate of the culture were able to reduce Cr(VI) while concentration of total chromium remained stable in the process, indicating that the enzyme-catalyzed mechanism was applied in Cr(VI) reduction by the isolate. Additionally, it was found that there was hardly any chromium on the cell surface of the strain, further supporting that reduction, rather than bioadsorption, plays a major role in the Cr(VI) removal.     

Binding and release of cholesterol in the Osh4 protein of yeast

Sterols have been shown experimentally to bind to the Osh4 protein (a homolog of the oxysterol binding proteins) of Saccharomyces cerevisiae within a binding tunnel, which consists of antiparallel beta-sheets that resemble a beta-barrel and three alpha-helices of the N-terminus. This and other Osh proteins are essential for intracellular transport of sterols and ultimately cell life. Molecular dynamics (MD) simulations are used to study the binding of cholesterol to Osh4 at the atomic level. The structure of the protein is stable during the course of all MD simulations and has little deviation from the experimental crystal structure. The conformational stability of cholesterol within the binding tunnel is aided in part by direct or water-mediated interactions between the 3-hydroxyl (3-OH) group of cholesterol and Trp(46), Gln(96), Tyr(97), Asn(165), and/or Gln(181) as well as dispersive interactions with Phe(42), Leu(24), Leu(39), Ile(167), and Ile(203). These residues along with other nonpolar residues in the binding tunnel and lid contribute nearly 75% to the total binding energy. The strongest and most populated interaction is between Gln(96) and 3-OH with a cholesterol/Gln(96) interaction energy of -4.5 +/- 1.0 kcal/mol. Phe(42) has a similar level of attraction to cholesterol with -4.1 +/- 0.3 kcal/mol. A MD simulation without the N-terminus lid that covers the binding tunnel resulted in similar binding conformations and binding energies when compared with simulations with the full-length protein. Steered MD was used to determine details of the mechanism used by Osh4 to release cholesterol to the cytoplasm. Phe(42), Gln(96), Asn(165), Gln(181), Pro(211), and Ile(206) are found to direct the cholesterol as it exits the binding tunnel as well as Lys(109). The mechanism of sterol release is conceptualized as a molecular ladder with the rungs being amino acids or water-mediated amino acids that interact with 3-OH.