Differential mRNA stability controls relative gene expression within the plasmid-encoded arsenical resistance operon.

The arsenical resistance (ars) operon of the conjugative plasmid R773 encodes an ATP-driven anion extrusion pump, conferring bacterial resistance to arsenicals. The operon contains a regulatory gene, arsR, and three structural genes, arsA, arsB, and arsC. The hydrophilic ArsA and ArsC proteins are produced in large amounts, but the hydrophobic ArsB protein, an integral membrane polypeptide, is synthesized in limited quantities. Northern (RNA-DNA) hybridizations provide evidence that the inducible operon is regulated at the level of transcription. The genes were transcribed in the presence of an inducer (arsenite) as a single polycistronic mRNA with an approximate size of 4.4 kilobases (kb). This transcript was processed to generate relatively stable mRNA species: one of 2.7 kb, encoding the ArsR and ArsA proteins, and a second of 0.5 kb, encoding the ArsC protein. Segmental differences in stability within the polycistronic transcript are proposed to account for the differential expression of the ars genes. In addition, analysis of the mRNA structure at the 5' end of arsB suggests a potential translational block to the synthesis of this membrane protein

Prevalence and Antimicrobial Susceptibility of Methicillin Resistant Staphylococcus aureus and Coagulase-Negative Staphylococci Isolated from Apparently Healthy University Students in Ota, Nigeria

In Nigeria, high prevalence of methicillin resistant Staphylococcus aureus (MRSA) in clinical samples and healthy individuals is increasingly being reported. However, very little is known regarding coagulase negative Staphylococci (CoNS) strains isolated from healthy individuals, especially, given their increasing recognition as agents of clinically significant infections and as reservoirs of antimicrobial resistance determinants. Therefore, this study was undertaken, to establish the prevalence of MRSA, and to characterize the antimicrobial susceptibility of CoNS strains from apparently healthy University student volunteers in Ota, Ogun State, Nigeria. A better characterization of CoNS strains in their commensal lifestyle could give us new insights on their pathogenic potential. A total of 100 (nose and neck swabs) samples were collected from healthy students and screened using standard microbiological techniques. Staphylococcus species isolated on the basis of growth on mannitol salt agar were further characterized based on biochemical tests and novobiocin resistance. Commercially prepared antibiotics discs were used to test the susceptibility of the Staphylococcus isolates obtained. Data generated were analyzed descriptively and expressed in percentages. A total of 39 Staphylococcus species were identified as S. aureus (17), S. saprophyticus (8), S. epidermidis (7), S. hemolyticus (5) and S. hominis (2). The S. aureus strains were highly resistant (>94%) to methicillin (oxacillin / cloxacillin) and several non-β-lactams including clindamycin (100%), co-trimoxazole (82.4%), and vancomycin (82.4%). The incidence of methicillin resistance among CoNS was 77.3% with moderate resistance to co-trimoxazole (63.6%), clindamycin (40.9%), gentamicin (36.36%) and vancomycin (31.8%). This study has demonstrated high prevalence of MRSA and MRCoNS isolates from apparently healthy University student volunteers in Ota, Nigeria, and underlines the need for periodic surveillance studies of this type, reassessment of policies on antibiotics use within and outside the University environments, development and enforcement of measures to prevent the spread of MRSA and MRCoNS infections in the community. Keywords: Coagulase-Negative Staphylococcus species (CoNS), Community-associated methicillin resistant Staphylococcus aureus (CA-MRSA), Multi-drug resistance, Nigeria, Susceptibilit

Biogas generation from Watermelon peels, Pineapple peels and Food wastes

the anaerobic digestion process for biogas production was investigated using locally available waste materials (watermelon peels, pineapple peels and food wastes). Watermelon peels and pineapple peels each was codigested with food wastes in ratio 1:1 while using rumen contents of cattle as inoculum. The physical, chemical and microbial characteristics of the three substrates were determined before and after the co-digestion process using standard methods. Analysis of the generated gas revealed 68.0% Methane, 20.0% Carbon dioxide, 6.0% Nitrogen, 2.5% Hydrogen, 1.5% Hydrogen sulfide and 2.0% Oxygen for co-digestion of watermelon peels with food wastes while co-digestion of pineapple peels with food wastes yielded 71.0% Methane, 18.0% Carbon dioxide, 7.0% Nitrogen,l.5% Hydrogen, 1.5% Hydrogen sulfide and 1.0% Oxygen. The anaerobic digestion was found to be efficient in terms of pathogen treatment, since the reduction of coliforms reached five logarithmic units. The availability and renewable nature of biomass, green energy production and ease of management and deployment of energy produced makes biogas a better option to fossil fuel and thus could be the much awaited solution to energy crisis in Nigeria and other developing nations

Construction of a Chimeric ArsA-ArsB Protein for Overexpression of the Oxyanion-translocating ATPase*

Resistance to toxic oxyanions of arsenic and antimony in Escherichia coli is conferred by the conjugative R-factor R773, which encodesa n ATP-driven anion extrusion pump. The ars operon is composed of three structuralg enes, arsA, arsBa, nd arsC. Although transcribed as a single unit, the three genes are differentially expressed as a result of translational differences, such that the ArsA and ArsC proteins are produced in high amounts relative to the amounot f ArsB protein made. Consequently, biochemical characterization of the ArsB protein, which is an integrmale mbrane protein containing the anion-conducting pathway, has been limited, precluding studies of the mechanism of this oxyanion pump. To overexpress tahres B gene, a series of changes were made. First, the second codon, an infrequently used leucine codon, was changed to a more frequently utilized codon. Second, a GC-rich stem-loop (AG = -17 kcal/mol) between the third and twelftcho dons was destabilized by changing several of the bases of the base-paired region. Third, the re-engineered arsB gene was fused 3’ in frame to the first 1458b ase pairs of the arsA gene to encodea 914-residue chimeric protein (486 residouf eths e ArsA protein plus 428 residues of the mutated ArsB protein) containing the entire re-engineered ArsB sequence except for the initiatinmg ethionine. The ArsA-ArsB chimera has been overexpressed at -15-20% of the total membrane proteins. Cells producing the chimeric ArsA-ArsB protein with an arsA gene in trans excluded 73AsO; from cells, demonstrating that the chimera can function as a component of the oxyaniontranslocating ATPase

Dietary and physical activity habits of All Saints University College of Medicine Students, St Vincent and the Grenadines

Background: The purpose of this research was to assess the dietary and physical activity habits of All Saints University College of Medicine students to determine if they were meeting the Saint Vincent and the Grenadines government’s dietary guidelines and to ascertain the prevalence of overweight and obesity among the students.Methods: Data were collected from the participants using a survey concerned with demographics, and self-assessment on dietary and physical activity habits. Descriptive statistics was used to report and analyse the data.Results: Study subjects consisted of 76 students. Eighty three percent of them were between the ages of 16 and 25 years. Sixty–one percent were female and 39% were male. The majority of the student respondents (76%) were aware of the importance of eating healthy and being physically active each day, and 50-66% of the respondents engaged in and enjoyed physical activity, achieved the recommended daily amount of vegetable intake, were at a normal body mass index (18.5-24.9 kg/m2) and reported satisfaction with their weight. However, majority (80%) of the respondents consumed fast food; about a third of them did not consume fruits nor exercise regularly, reporting lack of time, interest and self-discipline as major reasons.Conclusions: The results indicate that the majority of All Saints University Medical College students had high level of knowledge of overweight and obesity and were involved in some healthy behaviours that helped them achieve normal BMI. However, the poor nutritional and physical activity habits of many of the students could benefit from intervention programs to moderate the tendency for overweight and obesity in the student population

Synergy of Siam weed (Chromolaena odorata) and poultry manure for energy generation: Effects of pretreatment methods, modeling and process optimization

The co-digestion of Chromolaena odorata with poultry manure was evaluated in this study. Two samples of the weed: (A: which was pre-treated with mechanical, chemical and thermal methods) and (B: which was pretreated using mechanical and chemical methods only) were separately digested with poultry manure. Biogas generation started from the 2nd to 4th and 4th to 7th day for samples ‘A’ and ‘B’ respectively. The most desired actual biogas yield from samples ‘A’ and ‘B’ were 3884.20 and 2544.70 (10�4 m3/kg VS) respectively and the gas composition was 68 ± 2% Methane and 20 ± 2% Carbon dioxide for sample A while it was 62 ± 3% Methane and 22 ± 2% Carbon dioxide for sample B. In all, there was a 38.06% increase in gas generation in ‘A’ over ‘B’. The coefficient of determination (R2) for the Response Surface Methodology (RSM) model (0.9009) was high suggesting high accuracy in the modeling and prediction. The worldwide usage of C. odorata is encouraged

Mesophilic anaerobic co-digestion of poultry dropping and Carica papaya peels: Modelling and process parameter optimization study

The study evaluated anaerobic co-digestion of poultry dropping and pawpaw peels and the optimization of important process parameters. The physic-chemical analyses of the substrates were done using standard methods after application of mechanical, thermal and chemical pre-treatments methods. Gas chromatography analysis revealed the gas composition to be within the range of 66–68% methane and 18– 23% carbon dioxide. The study equally revealed that combination of the different pre-treatment methods enhanced enormous biogas yield from the digestion. Optimization of the generated biogas data were carried out using the Response Surface Methodology and the Artificial Neural Networks. The coefficient of determination (R2) for RSM (0.9181) was lower compare to that of ANN (0.9828). This shows that ANN model gives higher accuracy than RSM model for the current. Further usage of Carica papaya peels for biogas generation is advocated

Molecular Analysis of an ATP-Dependent Anion Pump

The plasmid-borne arsenical resistance operon encodes an ATP-driven oxyanion pump for the extrusion of the oxyanions arsenite, antimonite and arsenate from bacterial cells. The catalytic component of the pump, the 63 kDa ArsA protein, hydrolysesATP in the presence of its anionic substrate antimonite (SbO;). The ATP analogue 5' -p-fluorosulphonylbenzoyladenosine was used to modify the ATP binding site (s) of the ArsA protein. From sequence analysis there are two potential nucleotide binding sites. Mutations were introduced into the N-terminal site. Purified mutant proteins were catalytically inactive and incapable of binding nucleotides. Conformational changes produced upon binding of substrates to the ArsA protein were investigated by measuring the effects of substrates on trypsin inactivation. The hydrophobic 45.5 kDa ArsB protein forms the membrane anchor for the ArsA protein. The presence of the ArsA protein on purified inner membrane can be detected immunologically. In the absence of the arsB gene no ArsA is found on the membrane. Synthesis of the ArsB protein is limiting for formation of the pump. Analysis ofmRNA structure suggests a potential translational block to synthesis of the ArsB protein. Northern analysis of the ars message demonstrates rapid degradation of the mRNA in the arsB region

A bifunctional exoglucanase-endoglucanase fusion protein

A fusion was constructed between the cex gene of Cellulomonas fimi, which encodes an exoglucanase, and the cenA gene of the same organism, which encodes an endoglucanase. The cex-cenA fusion was expressed in Escherichia coli to give a fusion protein with both exoglucanase and endoglucanase activities. The fusion protein, unlike the cex and the cenA gene products from E. coli, did not bind to microcrystalline cellulose, presumably because it lacked an intact substrate-binding region. The fusion protein was exported to the periplasm in E. coli

Characterization of Antiallodynic Actions of ALE-0540, a Novel Nerve Growth Factor Receptor Antagonist, in the Rat1

There is growing evidence that nerve growth factor (NGF) may function as a mediator of persistent pain states. We have identified a novel nonpeptidic molecule, ALE-0540, that inhibits the binding of NGF to tyrosine kinase (Trk) A or both p75 and TrkA (IC50 5.88 6 1.87 mM, 3.72 6 1.3 mM, respectively), as well as signal transduction and biological responses mediated by TrkA receptors. ALE-0540 was tested in models of neuropathic pain and thermally-induced inflammatory pain, using two routes of administration, a systemic i.p. and a spinal intrathecal (i.th.) route. Morphine was also tested for comparison in the antiallodynia model using mechanical stimuli. We show that either i.p. or i.th. administration of ALE-0540 in rats produced antiallodynia in the L5/L6 ligation model of neuropathic pain. The calculated A50 values (and 95% confidence intervals) for ALE- 0540 administered i.p. and i.th. were 38 (17.5– 83) mg/kg and 34.6 (17.3– 69.4) mg, respectively. ALE-0540 given i.th., at doses of 30 and 60 mg, also blocked tactile allodynia in the thermal sensitization model. Although morphine displayed greater potency [A50 value of 7.1 (5.6–8.8) mg/kg] than ALE- 0540 in anti-allodynic effect when given i.p. to L5/L6-ligated rats, it was not active when administered i.th. These data suggest that a blockade of NGF bioactivity using a NGF receptor antagonist is capable of blocking neuropathic and inflammatory pain and further support the hypothesis that NGF is involved in signaling pathways associated with these pain states. ALE-0540 represents a nonpeptidic small molecule which can be used to examine mechanisms leading to the development of agents for the treatment of pain