Copy Number Variation in Transcriptionally Active Regions of Sexual and Apomictic Boechera Demonstrates Independently Derived Apomictic Lineages

In asexual (apomictic) plants, the absence of meiosis and sex is expected to lead to mutation accumulation. To compare mutation accumulation in the transcribed genomic regions of sexual and apomictic plants, we performed a double-validated analysis of copy number variation (CNV) on 10 biological replicates each of diploid sexual and diploid apomictic Boechera, using a high-density (>700 K) custom microarray. The Boechera genome demonstrated higher levels of depleted CNV, compared with enriched CNV, irrespective of reproductive mode. Genome-wide patterns of CNV revealed four divergent lineages, three of which contain both sexual and apomictic genotypes. Hence genome-wide CNV reflects at least three independent origins (i.e., expression) of apomixis from different sexual genetic backgrounds. CNV distributions for different families of transposable elements were lineage specific, and the enrichment of LINE/L1 and long term repeat/Copia elements in lineage 3 apomicts is consistent with sex and meiosis being mechanisms for purging genomic parasites. We hypothesize that significant overrepresentation of specific gene ontology classes (e.g., pollen–pistil interaction) in apomicts implies that gene enrichment could be an adaptive mechanism for genome stability in diploid apomicts by providing a polyploid-like system for buffering the effects of deleterious mutations.     

Efficacy of neem compost on root knot nematode pest of Lagos spinach,Celosia argentea

The effects of neem compost on root knot nematode, Meloidogyne incognita, pest of Lagos spinach, Celosia argentea, cv. TLV 8, was studied during 2010 and 2011 planting seasons on the field. The trial was conducted at the Teaching and Research Farm of Ladoke Akintola University of Technology, Ogbomoso, Nigeria. There were four treatments, replicated five times fitted into randomised complete block design. Neem compost was applied at 1.0, 1.5 and 2.0?tonnes/ha. Experimental plots, where no compost was applied served as the control. The result obtained shows that Lagos spinach treated with neem compost significantly (p?<?0.05) reduced the final soil nematode population and root infections (damage), with resultant improvement on crop growth and yield. The result of the chemical analysis of the neem compost revealed the presence of flavonoids, sterols, glycosides, alkaloids and saponins.     

Glucose-6-phosphate as a probe for the glucosamine-6-phosphate N-acetyltransferase Michaelis complex

Glucosamine-6-phosphate N-acetyltransferase (GNA1) catalyses the N-acetylation of d-glucosamine-6-phosphate (GlcN-6P), using acetyl-CoA as an acetyl donor. The product GlcNAc-6P is an intermediate in the biosynthesis UDP-GlcNAc. GNA1 is part of the GCN5-related acetyl transferase family (GNATs), which employ a wide range of acceptor substrates. GNA1 has been genetically validated as an antifungal drug target. Detailed knowledge of the Michaelis complex and trajectory towards the transition state would facilitate rational design of inhibitors of GNA1 and other GNAT enzymes. Using the pseudo-substrate glucose-6-phosphate (Glc-6P) as a probe with GNA1 crystals, we have trapped the first GNAT (pseudo-)Michaelis complex, providing direct evidence for the nucleophilic attack of the substrate amine, and giving insight into the protonation of the thiolate leaving group.     

Hesperidin attenuates inflammation and oxidative damage in pleural exudates and liver of rat model of pleurisy

Objectives: This study investigated the potential anti-inflammatory effect of hesperidin against carrageenan induced pleurisy in rat model.

Methods: Twenty-four adult female Wistar rats (350 - 450g) were grouped as follows: Group I: rats were administered saline solution only (Normal control group); Group II: rats were administered saline solution (NaCl 0.9%) orally and injected with carrageenan (Inflammation control group); Group III: rats were administered hesperidin only (Hesperidin group); Group IV: rats were administered hesperidin orally and intrapleurally injected with 2% carrageenan (Inflammation treated with hesperidin group). The exudate volume, total leukocyte count, reactive oxygen species (ROS), myeloperoxidase (MPO),δ–aminolevulinate dehydratase (δ-ALA-D), catalase (CAT), superoxide dismutase (SOD), activities as well as non-protein thiol group (NPSH) and thiobarbituric acid reactive substances (TBARS) levels were determined.

Results: Pretreatment with hesperidin at a dose of 80 mg/kg orally per day for 21 days, minimized the increase in pleural exudate volume and leucocyte count and modulated the activities of MPO, SOD and CAT, as well as the levels of ROS, NPSH and TBARS in carrageenan-induced rats.

Conclusion: Our results suggest that hesperidin can elicit its anti-inflammatory action by blocking exudate and leukocyte influx into pleural cavity, inhibiting MPO activity and preventing oxidative damage.     

Genetic validation of Aspergillus fumigatus phosphoglucomutase as a viable therapeutic target in invasive aspergillosis

Aspergillus fumigatus is the causative agent of invasive aspergillosis, an infection with mortality rates of up to 50%. The glucan-rich cell wall of A. fumigatus is a protective structure that is absent from human cells and is a potential target for antifungal treatments. Glucan is synthesized from the donor uridine diphosphate glucose, with the conversion of glucose-6-phosphate to glucose-1-phosphate by the enzyme phosphoglucomutase (PGM) representing a key step in its biosynthesis. Here, we explore the possibility of selectively targeting A. fumigatus PGM (AfPGM) as an antifungal treatment strategy. Using a promoter replacement strategy, we constructed a conditional pgm mutant and revealed that pgm is required for A. fumigatus growth and cell wall integrity. In addition, using a fragment screen, we identified the thiol-reactive compound isothiazolone fragment of PGM as targeting a cysteine residue not conserved in the human ortholog. Furthermore, through scaffold exploration, we synthesized a para-aryl derivative (ISFP10) and demonstrated that it inhibits AfPGM with an IC₅₀ of 2 μM and exhibits 50-fold selectivity over the human enzyme. Taken together, our data provide genetic validation of PGM as a therapeutic target and suggest new avenues for inhibiting AfPGM using covalent inhibitors that could serve as tools for chemical validation.     

Prevalence of multiple antibiotic resistance among bacterial isolates from selected poultry waste dumps in Southwestern Nigeria

The prevalence of multiple antibiotic resistant bacteria in the waste dumpsite of ten poultry farms in Southwestern Nigeria was investigated. The susceptibility of 195 organisms isolated from the study sites to eight antimicrobial agents were tested using disc diffusion method and the minimum inhibitory concentration of cloxacillin and amoxicillin determined by the agar dilution method. Resistance to the test antibiotics ranged between 0% for gentamicin and 100% for tetracycline and ampicillin among the organisms. Overall, 70 and 90% of the isolates from Okuku, 65.2 and 95.6% from Ogbomoso, and 46.1 and 84.6% from Oyo had MIC above 512 μg/ml for amoxicillin and cloxacillin. Generally, drugs used in high volumes in the studied farms are the least active against the bacterial isolates. Results of this study shows that poultry waste can serve as environmental reservoirs of multiple antibiotic resistant bacteria and their indiscriminate dumping in the environment can expose surrounding human populations to health risks from drug resistant zoonotic pathogens. Part of the data presented in this paper was the subject of a presentation at the World Congress of Pharmacy and Pharmaceutical Sciences/67TH International Congress of the International Pharmaceutical Federation (FIP), 31 August—6 September 2007, Beijing, People’s Republic of China.     

Influence of rock dust-based soil re-mineralisation on root-knot disease of organic watermelon plants

Deplorable soil fertility characterising resource-poor agrarian communities remain a major constraint for sustainable global food security. Re-mineralisation through application of rock dust encourages maintainable productivity of degraded soils. This study was planned to appraise the effect of rock dust on root-knot disease of Citrullus lanatus caused by Meloidogyne incognita (Mi). The experiment was laid out in Randomised Complete Block Design with three replications. Soil and root populations of the nematode were estimated and galling damage of the crop was diagnosed and censured at 60?days after inoculation. Additional data were collected on vine length, number of leaves, days to 50% flowering and dry matter content. Data collected were subjected to analysis of variance and the means were separated using least significant difference. The treated watermelon plants were low in root-knot disease, significantly reduced Mi nematode populations and flowered far much earlier (p?=?0.05) than the untreated organic watermelon plants.     

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.