Reconstructing an ancestral genotype of two hexachlorocyclohexane-degrading Sphingobium species using metagenomic sequence data.

Over the last 60 years, the use of hexachlorocyclohexane (HCH) as a pesticide has resulted in the production of >4 million tons of HCH waste, which has been dumped in open sinks across the globe. Here, the combination of the genomes of two genetic subspecies (Sphingobium japonicum UT26 and Sphingobium indicum B90A; isolated from two discrete geographical locations, Japan and India, respectively) capable of degrading HCH, with metagenomic data from an HCH dumpsite (∼450 mg HCH per g soil), enabled the reconstruction and validation of the last-common ancestor (LCA) genotype. Mapping the LCA genotype (3128 genes) to the subspecies genomes demonstrated that >20% of the genes in each subspecies were absent in the LCA. This includes two enzymes from the 'upper' HCH degradation pathway, suggesting that the ancestor was unable to degrade HCH isomers, but descendants acquired lin genes by transposon-mediated lateral gene transfer. In addition, anthranilate and homogentisate degradation traits were found to be strain (selectively retained only by UT26) and environment (absent in the LCA and subspecies, but prevalent in the metagenome) specific, respectively. One draft secondary chromosome, two near complete plasmids and eight complete lin transposons were assembled from the metagenomic DNA. Collectively, these results reinforce the elastic nature of the genus Sphingobium, and describe the evolutionary acquisition mechanism of a xenobiotic degradation phenotype in response to environmental pollution. This also demonstrates for the first time the use of metagenomic data in ancestral genotype reconstruction, highlighting its potential to provide significant insight into the development of such phenotypes

Multicritical Points in an Ising Random-Field Model

The phase diagram of the mean-field Ising model in a random field obeying a symmetric three-peak distribution is determined. This distribution is relevant to diluted antiferromagnets in a uniform magnetic field. The phase diagram includes a fourth-order point, tricritical points, ordered critical points, critical end points, and a double critical end point. An ordered phase persists for arbitrarily large random fields at low temperatures

Formulation And Characterization of Carageenan Gels Encapsulating Amphotericin B And Lactobacillus acidophilus Against Candidal Vaginitis

The present study is concerned with the development and characterization of bioadhesive carageenan gel encapsulating Amphotericin B and Lactobacillus acidophillus, prepared by graft co-polymeriztion against Candidal vaginitis. Intravaginal gel systems based on bioadhesive polymer (carrageenan) were characterized with respect to swelling index, bioadhesive strength, percent encapsulation and in vitro drug release antimicrobial studies. A marked increase in swelling index of gel encapsulating Lactobacillus was found to be 1.9±0.35. The percent encapsulation of drug was found to be 98.63%±.0.2% and that of Lactobacillus was 91.81 ±0.01. The viability was observed for interval of 6 hrs on trypton soya agar and showed that viability was highly conserved till 4 hrs. The antimicrobial study of gels encapsulating Amphotericin B and Lactobacillus showed that carageenan gel can inhibit Candida albicans upto a maximum extent. Bioadhesivity study also conducted for gels that showed a bioadhesivity of 84.66% ±.0.5% with drug, 88.66% ±.02% with Lactobacillus. In-vitro drug release showed a sustained type release of drug from the polymer i.e. there was initial burst of Amphotericin B up to 5 hours, after which there was a sustained release upto 10 days. Thus it has been concluded from the present study that bioadhesive gels encapsulating Amphotericin B can act as promising drug carriers along with Lactobacillus against candidal vaginitis

Antibiofilm Potential of Metal Based Nanoparticles: Synthesis and Mode of Action

oai:ojs.pkp.sfu.ca:article/2Biofilm refers to a group of microbes colonizing together and often adhered to a surface. The adherence is attributed to secretion of polymeric substances comprising of extracellular DNA, proteins, and polysaccharides thereby limiting the access and inhibitory activity of existing antimicrobial agents. Biofilm are a major cause of acute infections and pose immense clinical threat especially in conditions employing the use of invasive devices thus being a major source of mortality and morbidity. Hence there is a dire need to develop alternative treatment against biofilm-related infections. Advances in nanotechnology has opened new horizons. Nanoparticles derived from various metal present promising candidates to ameliorate biofilms owing to their antioxidant potential

Behaviour of three charged particles on a plane under perpendicular magnetic field

We consider the problem of three identical charged particles on a plane under a perpendicular magnetic field and interacting through Coulomb repulsion. This problem is treated within Taut's framework, in the limit of vanishing center of mass vector $\vec{R} \to \vec{0}$, which corresponds to the strong magnetic field limit, occuring for example in the Fractional Quantum Hall Effect. Using the solutions of the biconfluent Heun equation, we compute the eigenstates and show that there is two sets of solutions. The first one corresponds to a system of three independent anyons which have their angular momenta fixed by the value of the magnetic field and specified by a dimensionless parameter $C \simeq \frac{l_B}{l_0}$, the ratio of $l_B$, the magnetic length, over $l_0$, the Bohr radius. This anyonic character, consistent with quantum mechanics of identical particles in two dimensions, is induced by competing physical forces. The second one corresponds to the case of the Landau problem when $C \to 0$. Finally we compare these states with the quantum Hall states and find that the Laughlin wave functions are special cases of our solutions under certains conditions.Comment: 15 pages, 3 figures, Accepeted in JP