Characterization of Colonizing Staphylococcus aureus Isolated from Surgical Wards' Patients in a Nigerian University Hospital

In contrast to developed countries, only limited data on the prevalence, resistance and clonal structure of Staphylococcus aureus are available for African countries. Since S. aureus carriage is a risk factor for postoperative wound infection, patients who had been hospitalized in surgical wards in a Nigerian University Teaching Hospital were screened for S. aureus carriage. All S. aureus isolates were genotyped (spa, agr) and assigned to multilocus sequence types (MLST). Species affiliation, methicillin-resistance, and the possession of pyrogenic toxin superantigens (PTSAg), exfoliative toxins (ETs) and Panton-Valentine Leukocidin (PVL) were analyzed. Of 192 patients screened, the S. aureus carrier rate was 31.8 % (n = 61). Of these isolates, 7 (11.5%) were methicillin-resistant (MRSA). The isolates comprised 24 spa types. The most frequent spa types were t064, t084, t311, and t1931, while the most prevalent MLST clonal complexes were CC5 and CC15. The most frequent PTSAg genes detected were seg/sei (41.0%) followed by seb (29.5%), sea (19.7%), seh (14.7%) and sec (11.5). The difference between the possession of classical and newly described PTSAg genes was not significant (63.9% versus 59.0% respectively; P = 0.602). PVL encoding genes were found in 39.3% isolates. All MRSA isolates were PVL negative, SCCmec types I and VI in MLST CC 5 and CC 30, respectively. Typing of the accessory gene regulator (agr) showed the following distribution: agr group 1 (n = 20), group II (n = 17), group III (n = 14) and group IV (n = 10). Compared to European data, enterotoxin gene seb and PVL-encoding genes were more prevalent in Nigerian methicillin-susceptible S. aureus isolates, which may therefore act as potential reservoir for PVL and PTSAg genes.     

Genetic and structural validation of Aspergillus fumigatus UDP‐N‐acetylglucosamine pyrophosphorylase as an antifungal target

The sugar nucleotide UDP‐N‐acetylglucosamine (UDP‐GlcNAc) is an essential metabolite in both prokaryotes and eukaryotes. In fungi, it is the precursor for the synthesis of chitin, an essential component of the fungal cell wall. U DP‐N‐a cetylglucosamine p yrophosphorylase (UAP) is the final enzyme in eukaryotic UDP‐GlcNAc biosynthesis, converting UTP and N‐acetylglucosamine‐1‐phosphate (GlcNAc‐1P) to UDP‐GlcNAc. As such, this enzyme may provide an attractive target against pathogenic fungi. Here, we demonstrate that the fungal pathogen Aspergillus fumigatus possesses an active UAP (AfUAP1) that shows selectivity for GlcNAc‐1P as the phosphosugar substrate. A conditional mutant, constructed by replacing the native promoter of the A. fumigatus uap1 gene with the Aspergillus nidulans alcA promoter, revealed that uap1 is essential for cell survival and important for cell wall synthesis and morphogenesis. The crystal structure of AfUAP1 was determined and revealed exploitable differences in the active site compared with the human enzyme. Thus AfUAP1 could represent a novel antifungal target and this work will assist the future discovery of small molecule inhibitors against this enzyme.     

Recycling of aquaculture wastewater using charcoal based constructed wetlands

Abstract

The competitive demand for water makes it a scarce resource for agricultural use. This necessitates wastewater reuse for irrigation and any other agricultural purpose, especially in developing countries where treatment of wastewaters is not a priority. The aim of this study was to evaluate the performance of a charcoal-based constructed wetland (CBCW) in treating aquaculture wastewater. Aquaculture wastewater from a Research Fishpond Farm was treated in a CBCW planted with Sacciolepsis africana and Commelina cyannae for 5?days retention time. Raw wastewater and the treated wastewater from the constructed wetland (CW) was sampled and the physicochemical parameters determined. The performance of the CW in treating aquaculture wastewater was conducted. The result showed that the CBCW was capable of removing 50% TSS, 88% COD, 93% BOD_5, and 100% nitrate nitrogen. The pH and DO of the wastewater before treatment and after treatment ranged from 6.68 to 6.91 and 4.13 to 6.30?mg/l, respectively. Thus, CWs have great potential for the treatment of aquaculture wastewater and prevention of environmental degradation through wastewater treatment, thereby solving the problem of water scarcity for agriculture for optimum food production.     

Paediatric Acute Kidney Injury in a Tertiary Hospital in Nigeria: Prevalence,Causes and Mortality Rate

Background

The modest decline in child mortality in Africa raises the question whether the pattern of diseases associated with acute kidney injury (AKI) in children in Nigeria has changed.

Methods

A database of children, aged between one month and 16 years, with AKI (using modified pediatric RIFLE criteria) was reviewed. The cause of AKI was defined as the major underlying disease. The clinical and laboratory features of children with AKI who survived were compared to those who died.

Results

Of the 4 015 children admitted into Lagos University Teaching Hospital between July 2010 and July 2012, 70 episodes of AKI were recorded equalling 17.4 cases per 1000 children. The median age of the children with AKI was 4.8 (range 0.1–14.4) years and 68.6% were males. Acute kidney injury was present in 58 (82.9%) children at admission with 70% in ‘failure’ category. Primary kidney disease (38.6%), sepsis (25.7%) and malaria (11.4%) were the commonest causes. The primary kidney diseases were acute glomerulonephritis (11) and nephrotic syndrome (8). Nineteen (28.4%) children with AKI died. Need for dialysis [odds ratio: 10.04 (2.94–34.33)], white cell >15 000/mm³ [odds ratio: 5.72 (1.65–19.89)] and platelet <100 000/mm³ [odds ratio: 9.56 (2.63–34.77)] were associated with death.

Conclusion

Acute kidney injury is common in children admitted to hospitals. The common causes remain primary kidney diseases, sepsis and malaria but the contribution of sepsis is rising while malaria and gastroenteritis are declining. Acute kidney injury-related mortality remains high.     

Ants of Forest and Fallow Plots in Nigeria1

Pitfall traps were used to monitor the activity of ants in a forest floor and a one-year-old fallow plot in Ile-Ife, Nigeria, at monthly intervals between November 1980 and October 1981. Similar studies were carried out between October 1987 and June 1988. These studies also included manual collection of ants from the floor of the experimental plots Of all the 10 species of ants recorded, Pbeihk crassinoda was the most abundant in the forest and fallow plots both in 1980–81 and 1987–88. P. crassinoda accounted for 52 percent and 88 percent of the ant populations collected manually from the forest and fallow plots respectively between December 1987 and June 1988. This species was also significantly higher in the pitfall catches of the fallow than the forest plots. Pitfall traps were not effective in sampling the populations of the belligerent Dorylus nigricans. The data are consistent with the widely accepted notion that forested areas support less ants than unforested areas. Differences in physical habitat characteristics, food availability, nesting habits, predation and microenvironmental factors were considered responsible for the differences in activities and abundance of ants in the forest and fallow plots.     

Microbial cell immobilization in biohydrogen production: a short overview

The high dependence on fossil fuels has escalated the challenges of greenhouse gas emissions and energy security. Biohydrogen is projected as a future alternative energy as a result of its non-polluting characteristics, high energy content (122?kJ/g), and economic feasibility. However, its industrial production has been hampered by several constraints such as low process yields and the formation of biohydrogen-competing reactions. This necessitates the search for other novel strategies to overcome this problem. Cell immobilization technology has been in existence for many decades and is widely used in various processes such as wastewater treatment, food technology, and pharmaceutical industry. In recent years, this technology has caught the attention of many researchers within the biohydrogen production field owing to its merits such as enhanced process yields, reduced microbial contamination, and improved homogeneity. In addition, the use of immobilization in biohydrogen production prevents washout of microbes, stabilizes the pH of the medium, and extends microbial activity during continuous processes. In this short review, an insight into the potential of cell immobilization is presented. A few immobilization techniques such as entrapment, adsorption, encapsulation, and synthetic polymers are discussed. In addition, the effects of process conditions on the performance of immobilized microbial cells during biohydrogen production are discussed. Finally, the review concludes with suggestions on improvement of cell immobilization technologies in biohydrogen production.     

Biogeographic variation in genetic variability,apomixis expression and ploidy of St. John's wort (Hypericum perforatum) across its native and introduced range

Background and Aims

St. John''s wort (Hypericum perforatum) is becoming an important model plant system for investigations into ecology, reproductive biology and pharmacology. This study investigates biogeographic variation for population genetic structure and reproduction in its ancestral (European) and introduced (North America) ranges.

Methods

Over 2000 individuals from 43 localities were analysed for ploidy, microsatellite variation (19 loci) and reproduction (flow cytometric seed screen). Most individuals were tetraploid (93 %), while lower frequencies of hexaploid (6 %), diploid (<1 %) and triploid (<1 %) individuals were also identified.

Key Results

A flow cytometric analysis of 24 single seeds per individual, and five individuals per population demonstrated opposite patterns between ploidy types, with tetraploids producing more apomictic (73 %) than sexual (24 %) seed, while hexaploids produced more sexual (73 %) than apomictic (23 %) seed. As hexaploids are derived from tetraploids, these data imply that gene dosage, in addition to the effects of hybridization, influences the switch from apomictic to sexual reproduction. No significant differences in seed production were found between Europe and North America. An analysis of population structure based upon microsatellite profiling demonstrated three major genetic clusters in Europe, whose distribution was reflective of Pleistocene glaciation (e.g. refugia) and post-glacial recolonization of Europe.

Conclusions

The presence of pure and mixed populations representing all three genetic clusters in North America demonstrates that H. perforatum was introduced multiple times onto the continent, followed by gene flow between the different gene pools. Taken together, the data presented here suggest that plasticity in reproduction has no influence on the invasive potential of H. perforatum.     

Properties of the isoforms of α-amylase from kilned and unkilned malted sorghum (Sorghum bicolor)

We have previously reported the presence of a relatively heat-stable α-amylase with a low K_m for starch in kilned malted sorghum. In order to establish the industrially useful and more efficient isoforms, we have separated this α-amylase into different isoforms using both cation and anion-exchange chromatographies. Unkilned malted α-amylase crude was separated into three different isoforms (a1, a2 and a3) whereas kilned samples were separated into two (a1 and a2). Apparently one isoform (a3) was lost during kilning due to heat lability. a1 isoform which appears to have a neutral pI and constitute about 60% of the total α-amylases protein that were induced during germination, have the lowest K_m for starch. They are more generally stable than other isoforms at all the temperatures studied. These isoforms lost only 10% activity at 80 °C for 30 min and still had some residual activity at 100 °C incubation for 30 min. a1 isoform could therefore be adapted for industrial starch conversion processes which are carried out within this range of gelatinizing temperatures because of its properties.     

Quantitative variation for apomictic reproduction in the genus Boechera (Brassicaceae)

? Premise of the study: The evolution of asexual seed production (apomixis) from sexual relatives is a great enigma of plant biology. The genus Boechera is ideal for studying apomixis because of its close relation to Arabidopsis and the occurrence of sexual and apomictic species at low ploidy levels (diploid and triploid). Apomixis is characterized by three components: unreduced embryo-sac formation (apomeiosis), fertilization-independent embryogenesis (parthenogenesis), and functional endosperm formation (pseudogamy or autonomous endosperm formation). Understanding the variation in these traits within and between species has been hindered by the laborious histological analyses required to analyze large numbers of samples. ? Methods: To quantify variability for the different components of apomictic seed development, we developed a high-throughput flow cytometric seed screen technique to measure embryo:endosperm ploidy in over 22000 single seeds derived from 71 accessions of diploid and triploid Boechera. ? Key results: Three interrelated features were identified within and among Boechera species: (1) variation for most traits associated with apomictic seed formation, (2) three levels of apomeiosis expression (low, high, obligate), and (3) correlations between apomeiosis and parthenogenesis/pseudogamy. ? Conclusions: The data presented here provide a framework for choosing specific genotypes for correlations with large "omics" data sets being collected for Boechera to study population structure, gene flow, and evolution of specific traits. We hypothesize that low levels of apomeiosis represent an ancestral condition of Boechera, whereas high apomeiosis levels may have been induced by global gene regulatory changes associated with hybridization.     

Resistance to Chilo infuscatellus (Lepidoptera: Pyraloidea) in transgenic lines of sugarcane expressing Bacillus thuringiensis derived Vip3A protein

Molecular Biology Reports - Sustainable agriculture requires management of insect pests through resistance development. The biological potential of Cry toxins and Vip protein, derived from Bacillus...