Anin vitro rearing system for the propagation of the ectoparasitoidCatolaccus grandis

An experimental ‘closed’ rearing system, where egg and larval manipulations were eliminated, was developed for the in vitro rearing of Catolaccus grandis (Hymenoptera: Pteromalidae) Burks, an important ectoparasitoid of the cotton boll weevil, Anthonomus grandis Boheman. In this rearing model, n-hexane (a synthetic ovipositional stimulant for this parasitoid), was smeared on the Parafilm® cover of a modified rearing chamber (a Multiwell®) tissue culture plate) to induce the deposition of uncontaminated eggs, on the inner side of this waxy membrane, and on or around an agar retained diet that had been dispensed into the individual chamber wells. When the efficiency of the in vitro rearing system was compared to the current in vivo rearing method for this species, the duration of the life cycle was significantly shorter in parasitoids reared in vivo, but this difference was less than one day (17.8 vs 17.1 days, respectively). On the other hand, the number of eggs laid in the in vitro rearing chamber during a 4 h period was c. 2.5 times greater than in the conventional in vivo rearing apparatus, and adult yields were c. 25% greater when using the in vitro closed rearing method. Male to female ratios were c. 1:9 when reared in vitro as compared to 1.0:1.5 for those reared in vivo. There were no apparent adverse effects of this in vitro rearing system on the parasitoid's general behavior and reproduction after two consecutive generations.     

Study of mixed function oxidase system in <Emphasis Type="Italic">Aspergillus ochraceus</Emphasis> (NCIM 1146)

Aspergillus ochraceus (NCIM-1146) has shown the ability to degrade cholesterol, camphor and naphthalene, when 96 h grown mycelium incubated in medium containing these organic compounds. Presence of higher level of electron transport components and biotransformation enzyme activity were observed in Aspergillus ochraceus, when grown in potato dextrose medium for 96 h. The enzyme activity preferred NADPH as a cofactor and shows inhibition in the presence of CO, indicating cytochrome P-450 mediated reactions. A significant increase in the levels of electron transport components and biotransformation enzyme activity were observed in presence of different inducers (viz. cholesterol, camphor, naphthalene, veratrole, phenobarbital, n-hexane, kerosene and saffola oil) when compared with mycelium incubated in same way with similar conditions for 2 min incubation. Analyses of the products of cholesterol and camphor using HPLC and GCMS confirm the degradation of these compounds.     

Identification and characterization of an organic solvent tolerance gene in Helicobacter pylori

BACKGROUND: Pre-cleaning and soaking in glutaraldehyde is the necessary procedure to disinfect endoscopes. However, some chemical-solvent-tolerant bacteria may survive after incomplete endoscopic disinfection. The goal of this study was to identify glutaraldehyde resistance-related genes in Helicobacter pylori. MATERIALS AND METHODS: Lambda-Zap phagemid expression library of H. pylori strain NTUH-C1 was selected with 0.1% glutaraldehyde. The minimal inhibitory concentration (MIC) of glutaraldehyde-resistant DNA fragments of H. pylori NTUH-C1 strain were determined. Imp/OstA recombinant protein was expressed, purified, and used to generate anti-Imp/OstA polyclonal antibody. Imp/ostA knockout, deletion, and complementation strains were constructed. The function of Imp/OstA was monitored by organic solvent tolerance assay, antibiotics susceptibility test, and N-phenylnapthylamine assay. RESULTS: Using Imp/ostA polyclonal antibody against cell lysate of wild-type and imp/ostA mutant showed that it is not essential in H. pylori. Organic solvent tolerance assay demonstrated the role of Imp/ostA in n-hexane tolerance. MIC test showed that the mutation of imp/ostA was susceptible to hydrophobic and beta-lactam antibiotics. NPN assay demonstrated that the level of outer membrane permeability was increased by 50% in mutant strain comparing to wild-type strain (p < .001). CONCLUSIONS: We have identified an Imp/OstA protein that was associated with glutaraldehyde resistance in our clinical strain H. pylori NTUH-C1 by screening of lambda-Zap expression library. Disruption of this protein results in altering membrane permeability, sensitivity to organic solvent, and susceptibility to antibiotics.     

Gibbs-Ensemble Molecular Dynamics: Liquid-Gas Equilibria for Lennard-Jones Spheres and n-Hexane

Abstract

We present a novel method to simulate phase equilibria in atomic and molecular systems. The method is a Molecular Dynamics version of the Gibbs-Ensemble Monte Carlo technique, which has been developed some years ago for the direct simulation of phase equilibria in fluid systems. The idea is to have two separate simulation boxes, which can exchange particles (or molecules) in a thermodynamically consistent fashion. Here we pres the derivation of the generalized equations of motion and discuss the relation of the resulting trajectory averages to the relevant ensemble. We test this Gibbs-Ensemble Molecular Dynamics algorithm by applying it to an atomic and a molecular system, i.e. to the liquid-gas coexistence in a Lennard-Jones fluid and in n-hexane. In both cases our results are in good accord with previous mean field and Gibbs-Ensemble Monte Carlo results as well as with the experimental data in the case of hexane. We also show that our Gibbs-Ensemble Molecular Dynamics algorithm like other Molecular Dynamics techniques can be used to study the dynamics of the system. Self-diffusion coefficients calculated with this method are in agreement with the result of conventional constant temperature Molecular Dynamics.     

MTT assay based inhibition analysis of A2780 cells proliferation using Mollugo nudicaulis Lam. extract with CXCR4 and HER2 expression

It is of interest to document the inhibition of A2780 cell proliferation using Mollugo nudicaulis Lam.(M.nudicaulis) extract by MTT assay and by monitoring the CXCR4 and HER2 expression through RT-PCR analysis. Results shown that the n-hexane extract of M.nudicaulis have anticancer activity IC₅₀ values of 32.46±0.92 µg/mL on A2780 cell lines. It is further found that the CXCR4 and HER2 mRNA and protein expression were significantly reduced in M.nudicaulis treated A2780 cell lines. Thus, the n-hexane extract of M.nudicaulis is a natural source of bioactive compounds as potential anticancer agents.     

The Role of Metabolism in Establishing Chemical-Specific Adjustment Factors for n-Hexane and Methyl n-Butyl Ketone

This paper focuses on the derivation of chemical-specific adjustment factors (CSAFs) for two neurotoxic solvents, n-hexane and methyl n-butyl ketone (MBK). Workers are exposed to the chemicals mainly via inhalation when they are used, for example, as solvents in adhesives. In order to derive CSAFs for n-hexane and MBK, research data were used from animal studies conducted in our laboratory. Also, MEDLINE and TOXLINE databases were searched for references containing animal and human toxicokinetic and toxicodynamic data. International Programme on Chemical Safety (IPCS) guidelines were followed. From the available data, the composite factor (CF) for n-hexane was calculated to be 18.2. Because n-hexane and MBK are most often used in combination with other solvents, e.g., methyl ethyl ketone (MEK), the metabolic induction of the toxicity of n-hexane or MBK by MEK should be considered in the derivation of CSAFs. However, in the presence of MEK the calculated CF for both n-hexane and MBK is 13. As more human data become available, the CFs for the mixtures may be reduced compared to the individual chemicals.