Diverse reactions catalyzed by naphthalene dioxygenase fromPseudomonas sp strain NCIB 9816

Naphthalene dioxygenase (NDO) fromPseudomonas sp strain NCIB 9816 is a multicomponent enzyme system which initiates naphthalene catabolism by catalyzing the addition of both atoms of molecular oxygen and two hydrogen atoms to the substrate to yield enantiomerically pure (+)-cis-(1R,2S)-dihydroxy-1,2-dihydronaphthalene. NDO has a relaxed substrate specificity and catalyzes the dioxygenation of many related 2- and 3-ring aromatic and hydroaromatic (benzocyclic) compounds to their respectivecis-diols. Biotransformations with a diol-accumulating mutant, recombinant strains and purified enzyme components have established that in addition tocis-dihydroxylation, NDO also catalyzes a variety of other oxidations which include monohydroxylation, desaturation (dehydrogenation),O-andN-dealkylation and sulfoxidation reactions. In several cases, the absolute stereochemistry of the oxidation products formed by NDO are opposite to those formed by toluene dioxygenase (TDO). The reactions catalyzed by NDO and other microbial dioxygenases can yield specific hydroxylated compounds which can serve as chiral synthons in the preparation of a variety of compounds of interest to pharmaceutical and specialty chemical industries. We present here recent work documenting the diverse array of oxidation reactions catalyzed by NDO. The trends observed in the oxidation of a series of benzocyclic aromatic compounds are compared to those observed with TDO and provide the basis for prediction of regio- and stereospecificity in the oxidation of related substrates. Based on the types of reactions catalyzed and the biochemical characteristics of NDO, a mechanism for oxygen activation by NDO is proposed.     

Sequence of a cDNA for mouse thymidylate synthase reveals striking similarity with the prokaryotic enzyme

We report the nucleotide sequence of a cloned cDNA, pMTS-3, that contains a 1-kb insert corresponding to mouse thymidylate synthase (E.C. 2.1.1.45). The open reading frame of 921 nucleotides from the first AUG to the termination codon specifies a protein with a molecular mass of 34,962 daltons. The predicted amino acid sequence is 90% identical with that of the human enzyme. The mouse sequence also has an extremely high degree of similarity (as much as 55% identity) with prokaryotic thymidylate synthase sequences, indicating that thymidylate synthase is among the most highly conserved proteins studied to date. The similarity is especially pronounced (as much as 80% identity) in the 44-amino-acid region encompassing the binding site for deoxyuridylic acid. The cDNA sequence also suggests that mouse thymidylate synthase mRNA lacks a 3' untranslated region, since the termination codon, UAA, is followed immediately by a poly(A) segment.      

Identifying the neural circuitry of alcohol craving and relapse vulnerability

With no further intervention, relapse rates in detoxified alcoholics are high and usually exceed 80% of all detoxified patients. It has been suggested that stress and exposure to priming doses of alcohol and to alcohol-associated stimuli (cues) contribute to the relapse risk after detoxification. This article focuses on neuronal correlates of cue responses in detoxified alcoholics. Current brain imaging studies indicate that dysfunction of dopaminergic, glutamatergic and opioidergic neurotransmission in the brain reward system (ventral striatum including the nucleus accumbens) can be associated with alcohol craving and functional brain activation in neuronal systems that process attentional relevant stimuli, reward expectancy and experience. Increased functional brain activation elicited by such alcohol-associated cues predicted an increased relapse risk, whereas high brain activity elicited by affectively positive stimuli may represent a protective factor and was correlated with a decreased prospective relapse risk. These findings are discussed with respect to psychotherapeutic and pharmacological treatment options.     

The effects of a diet rich in docosahexaenoic acid on organ and vascular fatty acid composition in spontaneously hypertensive rats

Previous research has shown that dietary docosahexaenoic acid (DHA) attenuates the development of high blood pressure in young spontaneously hypertensive rats (SHR). The purpose of this study was to investigate the effects of dietary DHA on organ and vascular fatty acid composition in SHR. Given the important structural and functional role of fatty acids in cell membranes, alterations in fatty acid composition may contribute to the antihypertensive effect of DHA. SHR were fed a purified diet containing either a corn/soybean oil mixture (CSO, control) or a DHA-enriched oil for 6 weeks. The DHA diet markedly increased the levels of DHA in the aorta, renal artery, plasma, liver, heart, kidney, and lung by 5-, 15-, 7-, 6-, 3.8-, 3.5-, and 8.8-fold (P<0.001), respectively. The levels of eicosapentaenoic acid were also increased while there was a concomitant reduction in arachidonic and adrenic acids. Therefore, dietary DHA increases the incorporation of omega-3 polyunsaturated fatty acids in specific organs and vascular tissue in SHR at the expense of omega-6 polyunsaturated fatty acids.     

Geographical variation in temporal and spatial vocalization patterns of male harbour seals in the mating season

In the aquatically mating harbour seal, Phoca vitulina, oestrous females show marked differences in spatial and temporal distribution between geographical areas. This suggests that the males' display behaviour may also vary between areas. We recorded male vocalizations in two areas, the Moray Firth and Orkney, U.K. In the Moray Firth, females haul out on a few intertidal sandbars and travel along predictable routes to forage at sea. In Orkney, female haul out sites are much less influenced by tidal availability and females are much more dispersed. In the Moray Firth, males vocalized only during a short mating season, from 1 July to 12 August. Vocalizations varied significantly with the tide, the peak at high tide clearly coinciding with the period when most females were in the water. In contrast, vocalizations in Orkney were significantly related to both tidal and diel patterns. We suggest that the timing of male vocalizations reflects differences in female availability between sites. In the inner Moray Firth, vocalizations were heard throughout the females' range, whereas vocalizations in Orkney were heard only in two discrete areas. However, at both sites the density of vocalizing males was highest in narrow channels and/or along predictable female travel routes. Therefore, males clearly adapt their temporal and spatial behaviour patterns to variations in female distribution and density. These results suggest that male mating strategies in aquatically mating pinnipeds are more variable than was previously envisaged. Copyright 1999 The Association for the Study of Animal Behaviour.     

SUMO: a ubiquitin-like protein modifier

SUMO (Small Ubiquitin-related Modifier) is a small protein that covalently attaches to a lysine residue of another protein in a reversible fashion. SUMO attachment to its substrate proteins causes changes in the localization, activity, or binding partners of the substrate. SUMO has been shown to play a role in a multitude of processes; these include chromosome segregation, cell cycle progression, and DNA damage recovery. Defects in the SUMO pathway have been demonstrated to affect tumorigenesis and the inflammatory response as well as other human diseases.     

A limited survey of aflatoxins and fumonisins in retail maizebased products in the UK using immunoassay detection

A total of 27 maize-based products destined for human consumption were collected from retail outlets within the city of Glasgow in the UK and were analysed for the presence of aflatoxins using immunoaftinity column chromatography with fluorescence detection and for fumonisins by competitive ELISA. Aflatoxins were detected at a trace level below 4 in eight (30%) of the 27 samples tested, no sample contained aflatoxins at a high level although one sample of sweetcorn did contain aflatoxins at a level of 5-10 Fumonisins were detected in eight (30%) of the samples at levels from 1 to 8mgkg^-1 and a further eight samples contained fumonisin at a level below 1 mgkg^-1 but above the detectable level. The highest concentration of fumonisins was found in a sample of fine corn meal at 8-12mgkg^-1.     

Sprint,agility, strength and endurance capacity in wheelchair basketball players

The aims of the present study were, firstly, to determine the reliability and reproducibility of an agility T-test and Yo-Yo 10 m recovery test; and secondly, to analyse the physical characteristics measured by sprint, agility, strength and endurance field tests in wheelchair basketball (WB) players. 16 WB players (33.06 ± 7.36 years, 71.89 ± 21.71 kg and sitting body height 86.07 ± 6.82 cm) belonging to the national WB league participated in this study. Wheelchair sprint (5 and 20 m without ball, and 5 and 20 m with ball) agility (T-test and pick-up test) strength (handgrip and maximal pass) and endurance (Yo-Yo 10 m recovery test) were performed. T-test and Yo-Yo 10 m recovery test showed good reproducibility values (intraclass correlation coefficient, ICC = 0.74-0.94). The WB players’ results in 5 and 20 m sprints without a ball were 1.87 ± 0.21 s and 5.70 ± 0.43 s and with a ball 2.10 ± 0.30 s and 6.59 ± 0.61 s, being better than those reported in the literature. Regarding the pick-up test results (16.05 ± 0.52 s) and maximal pass (8.39 ± 1.77 m), players showed worse values than those obtained in elite players. The main contribution of the present study is the characterization of the physical performance profile of WB players using a field test battery. Furthermore, we demonstrated that the agility T-test and the aerobic Yo-Yo 10 m recovery test are reliable; consequently they may be appropriate instruments for measuring physical fitness in WB.