Mitochondrial DNA genetic diversity among four ethnic groups in Sierra Leone

Although there are numerous ethnic groups in Sierra Leone, the Mende and Temne together account for approximately 60% of the total population. To see if genetic differences could be observed among ethnic groups in Sierra Leone, the nucleotide sequence of the hypervariable 1 (HV1) region of mitochondrial DNA (mtDNA) was determined from samples of the two major ethnic groups, the Mende (n=59) and Temne (n=121), and of two minor ethnic groups, the Loko (n=29) and Limba (n=67). Among these 276 HV1 sequences, 164 individual haplotypes were observed. An analysis of molecular variance indicated that the distribution of these haplotypes within the Limba sample was significantly different from that of the other ethnic groups. No significant genetic variation was seen between the Mende, Temne, and Loko. These results indicate that distinguishing genetic differences can be observed among ethnic groups residing in historically close proximity to one another. Furthermore, we observed some mitochondrial DNA haplotypes that are common among the Sierra Leone ethnic groups but that have not been observed in other published studies of West African ethnic groups. Therefore, we may have evidence for mtDNA lineages that are unique to this region of West Africa.     

Lipase-catalyzed biosynthesis of cinnamoylated lipids in a selected organic solvent medium

Biosynthesis of cinnamoylated lipids through the lipase-catalyzed transesterification reaction of cinnamic acid with triolein was investigated in organic solvent media. Electrospray ionization-mass spectroscopy (ESI-MS) structural analysis of the reaction mixture revealed the formation of two major end products, monoleyl-1(3)-cinnamate and dioleyl-2-cinnamate. Decreasing the molar ratio of cinnamic acid to triolein from 1:1 to 1:4.5 resulted in an increase in the maximum bioconversion yield of cinnamoylated lipids from 19 to 42%, which remained constant at a lower ratio of 1:6. However, an excess of triolein appeared to have a more beneficial effect on the formation of dioleyl-2-cinnamate than monoleyl-1(3)-cinnamate, leading to different end product compositions at ratios of substrates. With cinnamic acid to triolein ratios of 1:4.5 and 1:6.0, an increase in the bioconversion yield of cinnamoylated lipids to 55% was achieved by adding 2.2 mgmL(-1) silica gel to the reaction mixture. Radical scavenging activity of cinnamoylated lipids, with 50% of radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging, was found to be higher than that of its corresponding phenolic acid.     

Holographic glucose sensors

A novel holographic sensor system capable of detecting dynamic changes in glucose concentration has been developed. The hologram is recorded within a bio-compatible hydrogel matrix containing phenylboronic acid derivatives. On binding glucose, the colour of the hologram red-shifts to longer wavelengths as the hydrogel expands and this colour change is used to quantify glucose concentration. However, phenylboronic acids are non-selective and bind a wide variety of cis-diols. In blood, glucose is the only sugar found free at high concentration, whilst other sugars are typically found as part of glycoproteins and macromolecular structures. Although glycoproteins have been shown to have no effect on the sensor, phenylboronic acids can bind lactate much more readily than glucose. We have designed two polymer hydrogel systems to increase the selectivity of the sensor for glucose over lactate. The first involved the use of high concentrations of 3-acrylamidophenylboronic acid (3-APB) whilst the second system utilised 2-acrylamido-5-fluorophenylboronic acid (5-F-2-MAPB). Both systems displayed an increased selectivity to glucose over lactate at physiological pH and ionic strength and could be deployed as selective holographic sensors for glucose detection in physiological fluids.     

Detection and precipitation of hepatitis B core antigen using a fusion bacteriophage

The nucleocapsids of hepatitis B virus (HBV) are made of 180 or 240 subunits of core proteins or known as core antigens (HBcAg). A fusion bacteriophage bearing the WSFFSNI sequence that interacts tightly to HBcAg was employed as a diagnostic reagent for the detection of the antigen using the phage-enzyme-linked immunosorbent (phage-ELISA), dot blot and immunoprecipitation assays. The results from phage-ELISA and dot blot assay showed that as low as 10 ng of HBcAg can be detected optimally by 1.0x10(12) pfu/ml fusion M13 bacteriophage. The sensitivity of the dot blot assay corresponds with that of the phage-ELISA. HBcAg in HBV positive serum samples can also be detected using the fusion phage via the phage-ELISA and phage-dot blot assay. The phage cross-linked to cyanogen bromide (CNBr) activated agarose can also be used to precipitate HBcAg in bacterial lysate. The optimum amount of phage needed for cross-linking to 1 g of agarose is about 7.0x10(6) pfu/ml which could also precipitate purified and unpurified HBcAg in bacterial lysate. This study demonstrates the potential of fusion bacteriophage bearing the sequence WSFFSNI as a diagnostic reagent and a ligand for the detection and purification of HBcAg respectively.     

PCR amplification of four genes coding for aminoglycoside-modifying enzymes in bacteria of clinical isolates from Jordan University Hospital

Three species of Gram-negative G(–) bacteria were chosen for this study: Escherichia spp. (29 isolates), Pseudomonas spp. (16 isolates) andEnterobacter spp. (17 isolates), utilizing colony PCR to detect genes coding for aminoglycoside-modifying enzymes. The 62 isolates were purified and cultured on nutrient broth media supplemented with 50 g kanamycin/ml. Only 17 out of the 62 isolates were resistant to kanamycin and were subjected to colony PCR protocol using 20 l cell lysate and eight sets of primers with each isolate. Sizing of the amplified fragments was carried out in order to determine the specificity of PCR. The 17 isolates were shown to carry the rrs, aacC2, aacA-aphD and aphA3 genes.