Gas-Vacuolated Strains of Microcyclus aquaticus

Two strains of gas-vacuolated heterotrophic bacteria have been isolated from freshwaters by using 0.01% peptone enrichments. Both are nonmotile, vibrioid organisms that form rings before division. In terms of these morphological traits and other characteristics, including nutritional characters and deoxyribonucleic acid base composition, these new isolates are very similar to Microcyclus aquaticus. It is proposed that they be considered strains of this species.     

Mass spectrometry provides accurate characterization of two genetic marker types in Bacillus anthracis

Epidemiological and forensic analyses of bioterrorism events involving Bacillus anthracis could be improved if both variable number tandem repeats (VNTRs) and single nucleotide polymorphisms (SNPs) could be combined on a single analysis platform. Here we present the use of electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS) to characterize 24 alleles from 6 VNTR loci and 11 alleles from 7 SNP loci in B. anthracis. The results obtained with ESI-FTICR-MS were consistent with independent results obtained from traditional approaches using electrophoretic detection of fluorescent products. However, ESI-FTICR-MS improves on the traditional approaches because it does not require fluorescent labeling of PCR products, minimizes post-PCR processing, obviates electrophoresis, and provides unambiguous base composition of both SNP and VNTR PCR products. In addition, ESI-FTICR-MS allows both marker types to be examined simultaneously and at a rate of approximately 1 sample per min. This technology represents a significant advance in our ability to rapidly characterize B. anthracis isolates using VNTR and SNP loci.     

Smokers’ Decision Making: More than Mere Risk Taking

The fact that smoking is bad for people’s health has become common knowledge, yet a substantial amount of people still smoke. Previous studies that sought to better understand this phenomenon have found that smoking is associated with the tendency to take risk in other areas of life as well. The current paper explores factors that may underlie this tendency. An experimental analysis shows that smokers are more easily tempted by immediate high rewards compared to nonsmokers. Thus the salience of risky alternatives that produce large rewards most of the time can direct smokers to make bad choices even in an abstract situation such as the Iowa Gambling Task. These findings suggest that the risk taking behavior associated with smoking is not related to the mere pursuit of rewards but rather reflects a tendency to yield to immediate temptation.     

PURIFICATION AND CHARACTERIZATION OF β‐GLUCOSIDASE FROM GREATER WAX MOTH Galleria mellonella L. (LEPIDOPTERA: PYRALIDAE)

The greater wax moth, Galleria mellonella, is one of the most ruinous pests of honeycomb in the world. Beta‐glucosidases are a type of digestive enzymes that hydrolytically catalyzes the beta‐glycosidic linkage of glycosides. Characterization of the beta‐glucosidase in G. mellonella could be a significant stage for a better comprehending of its role and establishing a safe and effective control procedure primarily against G. mellonella and also some other insect pests. Laboratory reared final instar stage larvae were randomly selected and homogenized for beta‐glucosidase activity assay and subsequent analysis. The enzyme was purified to apparent homogeneity by salting out with ammonium sulfate and using sepharose‐4B‐l ‐tyrosine‐1‐naphthylamine hydrophobic interaction chromatography. The purification was 58‐fold with an overall enzyme yield of 29%. The molecular mass of the protein was estimated as ca. 42 kDa. The purified beta‐glucosidase was effectively active on para/ortho‐nitrophenyl‐beta‐d ‐glucopyranosides (p‐/o‐NPG) with Km values of 0.37 and 1.9 mM and Vmax values of 625 and 189 U/mg, respectively. It also exhibits different levels of activity against para‐nitrophenyl‐β‐d ‐fucopyranoside (p‐NPF), para/ortho‐nitrophenyl β‐d ‐galactopyranosides (p‐/o‐NPGal) and p‐nitrophenyl 1‐thio‐β‐d ‐glucopyranoside. The enzyme was competitively inhibited by beta‐gluconolactone and also was very tolerant to glucose against p‐NPG as substrate. The Ki and IC₅₀ values of δ‐gluconolactone were determined as 0.021 and 0.08 mM while the enzyme was more tolerant to glucose inhibition with IC50 value of 213.13 mM for p‐NPG.     

The effects of cell recycling on the production of 1,3-propanediol by Klebsiella pneumoniae

The effects of both biomass age and cell recycling on the 1,3-propanediol (1,3-PDO) production by Klebsiella pneumoniae were investigated in a membrane-supported bioreactor using hollow-fiber ultrafiltration membrane module in two separate experiments. It was determined that older cells have a negative effect on 1,3-PDO production. The concentrations of by-products, such as acetic acid and ethanol, increased in cultures with older cells, whereas the concentrations of succinic acid, lactic acid and 2,3-butanediol decreased. The effect of cell recycling was comparatively studied at a cell recycling ratio of 100 %. The results showed that cell recycling had also negative effects on 1,3-PDO fermentation. It was hypothesized that both cell recycling and biomass age caused metabolic shifts to undesired by-products which then inhibited the 1,3-PDO production. On the other hand, the use of hollow-fiber ultrafiltration membrane module was found to be very effective in terms of removal of cells from the fermentation broth.     

Mice fed a lipogenic methionine-choline-deficient diet develop hypermetabolism coincident with hepatic suppression of SCD-1

Lipogenic diets that are completely devoid of methionine and choline (MCD) induce hepatic steatosis. MCD feeding also provokes systemic weight loss, for unclear reasons. In this study, we found that MCD feeding causes profound hepatic suppression of the gene encoding stearoyl-coenzyme A desaturase-1 (SCD-1), an enzyme whose regulation has significant effects on metabolic rate. Within 7 days of MCD exposure, hepatic SCD-1 mRNA decreased to nearly undetectable levels. By day 21, SCD-1 protein was absent from hepatic microsomes and fatty acids showed a decrease in monounsaturated species. These changes in hepatic SCD-1 were accompanied by signs of hypermetabolism. Calorimetry revealed that MCD-fed mice consumed 37% more energy than control mice (P = 0.0003). MCD feeding also stimulated fatty acid oxidation, although fatty oxidation genes were not significantly upregulated. Interestingly, despite their increased metabolic rate, MCD-fed mice did not increase their food consumption, and as a result, they lost 26% of their body weight in 21 days. In summary, MCD feeding suppresses SCD-1 in the liver, which likely contributes to hypermetabolism and weight loss. MCD feeding also induces hepatic steatosis, by an independent mechanism. Viewed together, these two disparate consequences of MCD feeding (weight loss and hepatic steatosis) give the appearance of an unusual form of lipodystrophy.     

Reactivity of nitroxyl-derived sulfinamides

Sulfinamide [RS(O)NH(2)] formation is known to occur upon exposure of cysteine residues to nitroxyl (HNO), which has received recent attention as a potential heart failure therapeutic. Because this modification can alter protein structure and function, we have examined the reactivity of sulfinamides in several systems, including a small organic molecule, peptides, and a protein. Although it has generally been assumed that this thiol to sulfinamide modification is irreversible, we show that sulfinamides can be reduced back to the free thiol in the presence of excess thiol at physiological pH and temperature. We have examined this sulfinamide reduction both in peptides, where a cyclic intermediate analogous to that proposed for asparagine deamidation reactions potentially can contribute, and in a small organic molecule, where the mechanism is restricted to a direct thiolysis. These studies suggest that the contribution from the cyclic intermediate becomes more important in environments with lower dielectric constants. In addition, although sulfinic acid [RS(O)OH] formation is observed upon prolonged incubations in water, reduction of sulfinamides is found to dominate in the presence of thiols. Finally, studies with the cysteine protease, papain, suggest that the reduction of sulfinamide to the free thiol is viable in a protein environment.