An ab initio computational study of thiamin synthesis from gaseous reactants of the interstellar medium

A set of chemical reactions is proposed to account for the formation of thiamin derivatives from gaseous reactants that have been identified in the interstellar medium, and may have been relevant to a prebiotic atmosphere. The gaseous mixture consisted of methanimine, acetonitrile, cyanoacetylene, ammonia, acetylene, allylene, hydrogen sulfide, thioformaldehyde, and hydrogen in the presence of water. Most of the reactions appear to be exothermic. The reactions have been shown to be feasible from the overall enthalpy changes in the ZKE approximation at the HF and MP2/6-31G(*) level.     

A vision of a world without polio: the OPV cessation strategy.

Once the eradication of wild poliovirus has been confirmed, the public health benefits of routine immunization with OPV will no longer outweigh the burden of disease either due to paralysis caused by OPV (vaccine associated paralytic polio), or by outbreaks caused by circulating vaccine-derived polioviruses. The eventual cessation of OPV use in routine immunization programmes worldwide will become necessary to assure a lasting eradication of polio. As the world moves towards polio eradication and its certification, preparations are therefore being intensified for OPV cessation, and the risk management framework for safe OPV cessation is being put in place. The framework includes bio-containment of all known poliovirus and potentially infected substances, development of an international stockpile of oral polio vaccine, ensuring a mechanism for continued global surveillance and response for polio after eradication has been certified, and national policies if countries decide to continue vaccinating with inactivated polio vaccine (IPV). It is ironic that the vaccine on which the world has depended for polio eradication will itself become a risk to eradication once the transmission of wild poliovirus has been interrupted. Final preparations for the eventual global and simultaneous cessation of OPV will require the same level of international cooperation and coordination that has brought the world to the verge of polio eradication.     

Predictors of Attendance in a Practical Clinical Trial of Two Pediatric Weight Management Interventions

The objective of this study was to evaluate demographic and psychosocial predictors of attendance in a family‐based behavioral weight management clinical trial. Ninety‐three children and adolescents aged 7–17 (Mean age = 11.59, s.d. = 2.6) who were either overweight or obese (Mean BMI percentile = 98.2) and their parents received either a 10‐session behavioral treatment or a three‐session brief family intervention in the context of a randomized clinical trial (10). Psychosocial and anthropometric measures were obtained before enrollment and at the end of 10 weeks for both treatment groups. Univariate linear regression and hierarchical multiple regression analyses were used to identify predictors of attendance to treatment from an a priori set of hypothesized predictors. Three variables demonstrated significant associations with the dependent variable, percent of treatment sessions attended. Specifically, distance from participant's home to treatment site, lower gross family income, and youth self‐report of depressive symptoms were each associated with lower percent attendance (all Ps < 0.05). These results corroborate (i.e., income, depressive symptoms) and expand (i.e., distance from treatment site) previous reports in the literature of potential barriers to effective treatment for pediatric obesity, and suggest the need for research on treatment delivery methods that could increase participation among low‐income families (e.g., eHealth, mHealth options). Depressive symptoms could represent an additional barrier to treatment attendance, suggesting that assessment and treatment for these symptoms may be appropriate before commencing weight management treatment.     

POSSIBLE ORIGIN FOR PORPHIN DERIVATIVES IN PREBIOTIC CHEMISTRY – A COMPUTATIONAL STUDY

A set of chemical reactions is postulated to account for the formation of the macrocyclic porphin structure, basic to the pyrrole derivatives chlorophyll, protoporphyrin, heme and bilirubin, important in photosynthesis, respiration and digestion. A set of equations is given for the prebiotic synthesis of porphin derivatives from the simple molecules; cyanoacetylene, diacetylene, carbon monoxide and ammonia that have been detected in space. A number of isomers of hydrogenated porphin arise which may lose hydrogen to give ultimately porphin and its dehydrogenated derivative. The reactions, while not unique, provide a pathway which has been shown to be feasible from the overall enthalpy changes in the ZKE approximation at the HF and MP2/6-31G* level     

Removal of dimethylphenols and ammonium in laboratory‐scale horizontal subsurface flow constructed wetlands

Phenolic compounds in industrial wastewaters are toxic pollutants and pose a threat to public health and ecosystems. More recently, focus is being directed toward combining the treatment of these compounds with a cost‐effective and environmentally sound technology. The removal efficiency of dimethylphenol and ammonium nitrogen was studied, for the first time, in three different laboratory‐scale horizontal subsurface flow constructed wetlands planted with Juncus effusus. Two of the wetlands used were filled with gravel. One of these was planted and the second left without vegetation. The third wetland was a hydroponic system. It was found that the removal efficiencies of dimethylphenol was dependent on the inflow loading of the contaminant and was higher in the planted systems. Both planted systems yielded 99% removal efficiency up to loads of 240 mg/d, compared to only 73% for the unplanted constructed wetland. Factors and processes such as redox dynamics, methanogenesis, reduction of ammonium and low nitrate and nitrite concentrations imply simultaneous aerobic and anaerobic dimethylphenol transformations. A significant surplus of organic carbon was detected in the planted wetlands, which may originate from intermediates of the dimethylphenol transformation processes and/or organic plant root exudates. The present study demonstrates that horizontal subsurface flow constructed wetlands are a promising alternative system for the treatment of effluents contaminated with dimethylphenol isomers.     

ISOLATION AND CHARACTERIZATION OF A VIRUS THAT INFECTS EMILIANIA HUXLEYI (HAPTOPHYTA)1

The isolation and characterization of a virus (designated EhV) that infects the marine coccolithophorid Emiliania huxleyi (Lohmann) Hay & Mohler are described. Three independent clones of EhV were isolated from Norwegian coastal waters in years 1999 and 2000. EhV is a double‐stranded DNA‐containing virus with a genome size of ～415 kilo‐base pairs. The viral particle is an icosahedron with a diameter of 160–180 nm. The virus particle contains at least nine proteins ranging from 10 to 140 kDa; the major capsid protein weighs ～54 kDa. EhV has a latent period of 12–14 h and a burst size of 400–1000 (mean, 620) viral particles per cell. A phylogenetic tree based on DNA polymerase amino acid sequences indicates EhV should be assigned to the Phycodnaviridae virus family and that the virus is most closely related to viruses that infect Micromonas pusilla and certain Chlorella species.     

Transformation and expression of an anaerobic fungal xylanase in several strains of the rumen bacterium Butyrivibrio fibrisolvens

AIMS: To obtain reliable transformation of a range of Butyrivibrio fibrisolvens strains and to express a Neocallimastix patriciarum xylanase gene in the recipients. METHODS AND RESULTS: Eight strains (H17c, E14, LP1309, LP1028, AR11a, OB156, LP210B and LP461A) of Bu. fibrisolvens were transformed by the Gram-positive vector pUB110. A xylanase expression/secretion cassette containing Bu. fibrisolvens promoter and signal peptide elements fused to catalytic domain II of the N. patriciarum xylanase A cDNA (xynANp) was inserted into pUB110 to create the plasmid pUBxynA. pUBxynA was used to transform seven of the Bu. fibrisolvens strains transformed by pUB110. In strain H17c pUBxynA, which produced native xylanase, 2.46 U mg-1 total xylanase activity was produced with 45% extracellular xylanase. In strain H17c pUMSX, 0.74 U mg-1 total xylanase activity was produced with 98% extracellular xylanase. H17c pUBxynA exhibited increased (28.7%) degradation of neutral detergent fibre compared with unmodified H17c; however, progressive loss of pUBxynA was observed in long-term cultivation. CONCLUSIONS: A stable transformation system was developed that was applicable for a range of Bu. fibrisolvens strains and high levels of expression of a recombinant xylanase were obtained in H17c which lead to increased fibre digestion. SIGNIFICANCE AND IMPACT OF THE STUDY: This stable transformation system with the accompanying recombinant plasmids will be a useful tool for further investigation aimed at improving ruminal fibre digestion.     

Intracellular ion and organic solute concentrations of the extremely halophilic bacterium <Emphasis Type="Italic">Salinibacter ruber</Emphasis>

Salinibacter ruber is a red obligatory aerobic chemoorganotrophic extremely halophilic Bacterium, related to the order Cytophagales. It was isolated from saltern crystallizer ponds, and requires at least 150 g l(-1) salt for growth. The cells have an extremely high potassium content, the ratio K(+)/protein being in the same range as in halophilic Archaea of the order Halobacteriales. X-ray microanalysis in the electron microscope of cells grown in medium of 250 g l(-1) salt confirmed the high intracellular K(+)concentrations, and showed intracellular chloride to be about as high as the cation concentrations within the cells. A search for intracellular organic osmotic solutes, using (13)C-NMR and HPLC techniques, showed glutamate, glycine betaine, and N-alpha-acetyllysine to be present in low concentrations only, contributing very little to the overall osmotic balance. The results presented suggest that the extremely halophilic Bacterium Salinibacteruses a similar mode of haloadaptation to that of the Archaea of the order Halobacteriales, and does not accumulate organic osmotic solutes such as are used by all other known halophilic and halotolerant aerobic Bacteria.     

Enrichment and Broad Representation of Plant Biomass-Degrading Enzymes in the Specialized Hyphal Swellings of Leucoagaricus gongylophorus,the Fungal Symbiont of Leaf-Cutter Ants

Leaf-cutter ants are prolific and conspicuous constituents of Neotropical ecosystems that derive energy from specialized fungus gardens they cultivate using prodigious amounts of foliar biomass. The basidiomycetous cultivar of the ants, Leucoagaricus gongylophorus, produces specialized hyphal swellings called gongylidia that serve as the primary food source of ant colonies. Gongylidia also contain plant biomass-degrading enzymes that become concentrated in ant digestive tracts and are deposited within fecal droplets onto fresh foliar material as ants incorporate it into the fungus garden. Although the enzymes concentrated by L. gongylophorus within gongylidia are thought to be critical to the initial degradation of plant biomass, only a few enzymes present in these hyphal swellings have been identified. Here we use proteomic methods to identify proteins present in the gongylidia of three Atta cephalotes colonies. Our results demonstrate that a diverse but consistent set of enzymes is present in gongylidia, including numerous plant biomass-degrading enzymes likely involved in the degradation of polysaccharides, plant toxins, and proteins. Overall, gongylidia contained over three quarters of all biomass-degrading enzymes identified in the L. gongylophorus genome, demonstrating that the majority of the enzymes produced by this fungus for biomass breakdown are ingested by the ants. We also identify a set of 40 of these enzymes enriched in gongylidia compared to whole fungus garden samples, suggesting that certain enzymes may be particularly important in the initial degradation of foliar material. Our work sheds light on the complex interplay between leaf-cutter ants and their fungal symbiont that allows for the host insects to occupy an herbivorous niche by indirectly deriving energy from plant biomass.