Carnitine palmitoyltransferase activities: Effects of serum albumin,acyl-CoA binding protein and fatty acid binding protein

The carnitine palmitoyltransferase activity of various subcellular preparations measured with octanoyl-CoA as substrate was markedly increased by bovine serum albumin at low M concentrations of octanoyl-CoA. However, even a large excess (500 M) of this acyl-CoA did not inhibit the activity of the mitochondrial outer carnitine palmitoyltransferase, a carnitine palmitoyltransferase isoform that is particularly sensitive to inhibition by low M concentrations of palmitoyl-CoA. This bovine serum albumin stimulation was independent of the salt activation of the carnitine palmitoyltransferase activity. The effects of acyl-CoA binding protein (ACBP) and the fatty acid binding protein were also examined with palmitoyl-CoA as substrate. The results were in line with the findings of stronger binding of acyl-CoA to ACBP but showed that fatty acid binding protein also binds acyl-CoA esters. Although the effects of these proteins on the outer mitochondrial carnitine palmitoyltransferase activity and its malonyl-CoA inhibition varied with the experimental conditions, they showed that the various carnitine palmitoyltransferase preparations are effectively able to use palmitoyl-CoA bound to ACBP in a near physiological molar ratio of 1:1 as well as that bound to the fatty acid binding protein. It is suggested that the three proteins mentioned above effect the carnitine palmitoyltransferase activities not only by binding of acyl-CoAs, preventing acyl-CoA inhibition, but also by facilitating the removal of the acylcarnitine product from carnitine palmitoyltransferase. These results support the possibility that the acyl-CoA binding ability of acyl-CoA binding protein and of fatty acid binding protein have a role in acyl-CoA metabolismin vivo.Abbreviations ACBP acyl-CoA binding protein - BSA bovine serum albumin - CPT carnitine palmitoyltransferase - CPT₀ malonyl-CoA sensitive CPT of the outer mitochondrial membrane - CPT malonyl-CoA insensitive CPT of the inner mitochondrial membrane - OG octylglucoside - OMV outer membrane vesicles - IMV inner membrane vesicles Affiliated to the Department of Experimental Medicine, University of Montreal     

Solid state production of polygalacturonase and xylanase by Trichoderma species using cantaloupe and watermelon rinds

Different solid state fermentation (SSF) sources were tested such as cantaloupe and watermelon rinds, orange and banana peels, for the production of polygalacturonase (PG) and xylanase (Xyl) by Trichoderma harzianum and Trichoderma virens. The maximum production of both PG and Xyl were obtained by T. harzianum and T. virnes grown on cantaloupe and watermelon rinds, respectively. Time course, moisture content, temperature, pH, supplementation with carbon and nitrogen sources were optimized to achieve the maximum production of both PG and Xyl of T. harzianum and T. virens using cantaloupe and watermelon rinds, respectively. The maximum production of PG and Xyl of T. harzianum and T. virens was recorded at 4–5 days of incubation, 50–66% moisture, temperature 28–35°C and pH 6–7. The influence of supplementary carbon and nitrogen sources was studied. For T. harzianum, lactose enhanced PG activity from 87 to 120 units/g solid, where starch and maltose enhanced Xyl activity from 40 to 55–60 units/g solid for T. virnes. Among the nitrogen sources, ammonium sulphate, ammonium nitrate, yeast extract and urea increased PG activity from 90 to 110–113 units/g solid for T. harzianum. Similarly, ammonium chloride, ammonium sulphate and yeast extract increased Xyl activity from 45 to 55–70 units/g solid for T. virens.     

3-Deoxyglucosone: A Potential Glycating Agent Accountable for Structural Alteration in H3 Histone Protein through Generation of Different AGEs

Advanced glycation end-products (AGEs) are heterogeneous group of compounds, known to be implicated in diabetic complications. One of the consequences of the Maillard reaction is attributed to the production of reactive intermediate products such as α-oxoaldehydes. 3-deoxyglucosone (3-DG), an α-oxoaldehyde has been found to be involved in accelerating vascular damage during diabetes. In the present study, calf thymus histone H3 was treated with 3-deoxyglucosone to investigate the generation of AGEs (N^ε-carboxymethyllysine, pentosidine), by examining the degree of side chain modifications and formation of different intermediates and employing various physicochemical techniques. The results clearly indicate the formation of AGEs and structural changes upon glycation of H3 by 3-deoxyglucosone, which may hamper the normal functioning of H3 histone, that may compromise the veracity of chromatin structures and function in secondary complications of diabetes.     

Microorganisms associated with stored food grains and milled products from Dacca city godowns

Microorganisms present in the stored seeds of rice belonging to three varieties (Pegu, Nazirshari and Berui) were investigated. Species belonging to 4 genera of fungi were isolated and identified from this source in addition to the colonies of bacteria. Flour samples (Atta and Besan) yielded species of fungi belonging to 9 genera in addition to the bacterial colonies. The number of fungal and bacterial colonies occurring per g of the samples are given. The isolates of bacteria were not identified. There is no report of such a study from East Pakistan.

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Zusammenfassung Mikroorganismen, die in drei Varietäten von eingelagertem Reis (Pegu, Nazirshabi, Berui) vorkommen, sind untersucht worden. Arten von vier Gattungen von Pilzen sind isoliert und identifiziert worden, Mehlproben (Atta und Besan) ergaben Pilzarten, die neun Gattungen angehörten. In beiden Fällen sind also Bakterienkolonien isoliert worden. Die Anzahl der Kolonien von Pilzen und von Bakterien per Gram ist angegeben. Die Kolonien von Bakterien sind nicht identifiziert worden. Es gibt keine ähnliche Untersuchung vom Östlichen Pakistan.

     

Burkholderia pseudomallei: Its Detection in Soil and Seroprevalence in Bangladesh

Background

Melioidosis, caused by Burkholderia pseudomallei, is an endemic disease in Bangladesh. No systematic study has yet been done to detect the environmental source of the organism and its true extent in Bangladesh. The present study attempted to isolate B. pseudomallei in soil samples and to determine its seroprevalence in several districts in Bangladesh.

Methodology and Results

Soil samples were collected from rural areas of four districts of Bangladesh from where culture confirmed melioidosis cases were detected earlier. Multiple soil samples, collected from 5–7 sampling points of 3–5 sites of each district, were cultured in Ashdown selective media. Suspected colonies of B. pseudomallei were identified by biochemical and serological test, and by polymerase chain reaction (PCR) using 16s rRNA specific primers. Blood samples were collected from 940 healthy individuals of four districts to determine anti- B. pseudomallei IgG antibody levels by indirect enzyme linked immunosorbent assay (ELISA) using sonicated crude antigen. Out of 179 soil samples, B. pseudomallei was isolated from two samples of Gazipur district which is located 58 km north of capital Dhaka city. Both the isolates were phenotypically identical, arabinose negative and showed specific 550bp band in PCR. Out of 940 blood samples, anti- B. pseudomallei IgG antibody, higher than the cut-off value (>0.8), was detected in 21.5% individuals. Seropositivity rate was 22.6%-30.8% in three districts from where melioidosis cases were detected earlier, compared to 9.8% in a district where no melioidosis case was either detected or reported (p<0.01). Seropositivity increased with the advancement of age from 5.3% to 30.4% among individuals aged 1–10 years and > 50 years respectively. The seropositivity rates were 26.0% and 20.6% in male and female respectively, while it was 20–27% among different occupational groups. No significant association was observed with gender (χ2 = 3.441, p = 0.064) or any occupational group (χ² = 3.835, p = 0.280).

Conclusion

This is the first study demonstrating the presence of B. pseudomallei in the environmental (soil) samples of Bangladesh. It also suggested that a large proportion of people, residing in these districts, were exposed to the organism.     

Cytotoxic chalcones and flavanones from the tree bark of Cryptocarya costata

A new flavanone, 7-hydroxy-5,6-dimethoxyflavanone (1), together with three other flavonoids, didymocarpin (2), 2',4'-dihydroxy-5',6'-dimethoxychalcone (3), and isodidymocarpin (4), had been isolated from the methanol extract of the tree bark of Cryptocarya costata. The structures of these compounds were determined based on spectral evidence, including UV, IR, 1-D and 2-D NMR, and mass spectra. Cytotoxic properties of compounds 1-4 were evaluated against murine leukemia P-388 cells. The chalcones 3 and 4 were found to have substantial cytotoxicity with IC50 of 5.7 and 11.1 microM, respectively.     

EilA, a HilA-like regulator in enteroaggregative Escherichia coli

Enteroaggregative Escherichia coli (EAEC) is increasingly recognized as a diarrhoeal pathogen in developing and industrialized countries. Most EAEC virulence factors thus far described are encoded on virulence plasmid pAA, yet recent completion of the EAEC genome has suggested the presence of additional factors encoded on chromosomal islands. Previous reports have recognized the presence of a type III secretion system (T3SS), designated ETT2, at the glyU locus of prototype EAEC strain 042, along with possible T3SS effectors at the selC locus. The selC locus was also noted to harbour homologues of Salmonella enterica regulator HilA and of invasin from Yersinia spp., yet previous publications suggested that these loci may be silent. Here, we show that the genes of the selC locus are present inconsistently among a collection of well-characterized EAEC strains. Notably, however, there was perfect correlation between the presence of hilA-homologue eilA and predicted Yersinia invasin homologue gene eaeX. We hypothesized that if expressed, the putative gene product EilA would contribute to EAEC virulence in part by activation of the T3SS and its effectors. An eilA mutant was constructed in EAEC strain 042, and complementation was achieved by cloning the eilA gene under control of an arabinose-dependent promoter. In this system, we observed expression of at least seven genes to be affected by expression of eilA, either directly or indirectly: selC locus genes eipB, eipC, eipD, eicA and eaeX (renamed here air), as well as glyU ETT2 genes eivF and eivA. Notably, the eilA mutant was shown to be less adherent to epithelial cells in culture and to form less abundant biofilms than the isogenic parent. These effects were recapitulated in the air mutant, suggesting that the predicted outer membrane protein product of the air gene is involved as an accessory adhesin and aggregin of EAEC, coexpressed with the T3SS. Our data suggest that the T3SS of EAEC and presumed effectors located on different chromosomal islands may be coordinately activated by EilA, which also activates the genetically linked high molecular weight bacterial surface protein Air. Contributions of this new putative virulence-related regulon in EAEC may include adherence, aggregation, and as yet uncharacterized roles for the T3SS.