Visual pigments in a living fossil,the Australian lungfish <Emphasis Type="Italic">Neoceratodus forsteri</Emphasis>

Background  

One of the greatest challenges facing the early land vertebrates was the need to effectively interpret a terrestrial environment. Interpretation was based on ocular adaptations evolved for an aquatic environment millions of years earlier. The Australian lungfish Neoceratodus forsteri is thought to be the closest living relative to the first terrestrial vertebrate, and yet nothing is known about the visual pigments present in lungfish or the early tetrapods.     

Acute toxicity effects of ibuprofen on behaviour and haematological parameters of African catfish Clarias gariepinus (Burchell, 1822)

Indiscriminate discharge of pharmaceutical waste into the aquatic ecosystem may pose serious health challenges to aquatic biota. The effect of acute exposure to ibuprofen was evaluated using changes in behaviour and haematological parameters under static bio-assay method in Clarias gariepinus. Test specimens were exposed to acute concentrations of ibuprofen (0.28, 0.33, 0.38, 0.43 and 0.48 mg l^?1) for 24, 48, 72 and 96 h durations respectively. Behavioural and phenotypic changes were observed in surviving fish. There were significant (p < 0.05) concentration and duration-dependent increases in erythrocyte (RBC), haemoglobin (Hb), pack cell volume (PCV) and leukocytes (WBC) in treated fish compared to the control. Insignificant decreases (p > 0.05) in mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC) were observed in treated fish compared to the control. Ibuprofen elicited dose and duration- dependent decrease in neutrophil counts with the decreases being significant (p < 0.05) in the higher doses of 0.43 and 0.48 mg l^?1. Ibuprofen did not elicit any significant changes in monocytes, basophils and eosinophils. Changes observed in this study showed that ibuprofen negatively affected the health of the fish and we recommend that discharge of ibuprofen into the aquatic environment should be monitored and controlled.     

Plasmodium falciparum gametocyte carriage, emergence, clearance and population sex ratios in anaemic and non-anaemic malarious children

Anaemia in falciparum malaria is associated with an increased risk of gametocyte carriage, but its effects on transmission have not been extensively evaluated in malarious children. Plasmodium falciparum gametocyte carriage, emergence, clearance, population sex ratios (SR) (defined as the proportion of gametocytes that are male), inbreeding rates and temporal changes in SR were evaluated in 840 malarious children. Gametocyte carriage pre-treatment was at a level of 8.1%. Anaemia at enrolment was an independent risk factor for gametocyte carriage post-treatment. The emergence of gametocytes seven days post-treatment was significantly more frequent in anaemic children (7/106 vs. 10/696, p = 0.002). In the initially detected gametocytes, the proportion of children with a male-biased SR (MBSR) (> 0.5) was significantly higher in anaemic children (6/7 vs. 3/10, p = 0.027). Pre-treatment SR and estimated inbreeding rates (proportion of a mother's daughters fertilised by her sons) were similar in anaemic and non-anaemic children. Pre-treatment SR became more female-biased in non-anaemic children following treatment. However, in anaemic children, SR became male-biased. Anaemia was shown to significantly increase gametocyte emergence and may significantly alter the SR of emerging gametocytes. If MBSR is more infective to mosquitoes at low gametocytaemia, then these findings may have significant implications for malaria control efforts in endemic settings where malaria-associated anaemia is common.     

Effect of Methanolic extract of Musa sapientum leaves on Gastrointestinal Transit time in Normal and Alloxan induced Diabetic rats: Possible Mechanism of Action

Disorders of gastrointestinal motility have been associated with Diabetes mellitus. Hyperglycaemia particularly has been reported to inhibit gastrointestinal transit time while glibenclamide, a sulphonylurea and insulin, both increased transit time. Musa sapientum has also been reported as an antidiabetic agent but there is dearth of information on the effect of this plant on gastrointestinal motility. This study was therefore carried out to investigate the effect of methanolic extract of Musa sapientum leaves (MEMSL) on Gastrointestinal Transit time (GITT) in male albino rats with and without hyperglycaemia and to elucidate possible mechanism by which this extract functions. Fifty five albino rats were divided into 11 groups of five animals each. All animals were fasted for 24hrs before the begining of the experiment. Group 1 served as control; while the remaining groups (2 - 11) were treated with 250mg/kg; 500mg/kg MEMSL; diabetic control; diabetic treated with 250mg/kg; 500mg/kg MEMSL; diabetic treated with glibenclamide (5mg/kg); normal rats treated with Nifedipine (50mg/kg); normal rats treated with calcium chloride (CaCl2) only (10mg/kg); groups 10 and 11 were both pretreated with CaCl2 and subsequently treated with 250mg/kg and 500mg/kg MEMSL respectively. All plant extracts used for treatments were dissolved in normal saline and administered orally using orogastric tube. Charcoal meal was used as marker in the estimation of GITT. The study showed significant decrease in GITT in the normal rats treated with 250mg/kg and 500mg/kg of extract. However, in the diabetic rats treated with 500mg/kg MEMSL, there was significant increase in GITT and this is comparable with the gut response to glibenclamide (5mg/kg). Musa sapientum extract produced significant decrease in transit time in the calcium chloride pre-treated normal rats and this is comparable to the effect observed in Nifedipine treated group. The significant reduction in GITT produced by MEMSL in the normal rats reflects a strong possibility of MEMSL acting as calcium channel antagonist through the voltage gated calcium channel which may be due to the presence of alkaloids, saponins, cardenolides. There is the possibility of the extract acting as an inhibitor of potassium channel at higher concentration as observed in glibenclamide treated groups. Keywords: Musa Sapientum, Gastrointestinal transit time, Alloxan diabetes.     

Channel Specificity and Secondary Structure of the Glucose-Inducible Porins of Pseudomonas spp.

The OprB porin-mediated glucose transport system was investigated in Pseudomonas chlororaphis, Burkholderia cepacia, and Pseudomonas fluorescens. Kinetic studies of [U-¹⁴C]glucose uptake revealed an inducible system of low K _m values (0.3–5 M) and high specificity for glucose. OprB homologs were purified and reconstituted into proteoliposomes. The porin function and channel preference for glucose were demonstrated by liposome swelling assays. Examination of the periplasmic glucose-binding protein (GBP) components by Western immunoblotting using P. aeruginosa GBP-specific antiserum revealed some homology between P. aeruginosa GBP and periplasmic proteins from P. fluorescens and P. chlororaphis but not B. cepacia. Circular dichroism spectropolarimetry of purified OprB-like porins from the three species revealed sheet contents of 31–50% in agreement with 40% sheet content for the P. aeruginosa OprB porin. These findings suggest that the high-affinity glucose transport system is primarily specific for glucose and well conserved in the genus Pseudomonas although its outer membrane component may differ in channel architecture and specificity for other carbohydrates.     

Tetranucleotide,trinucleotide, and dinucleotide loci from the bobcat (Lynx rufus)

We describe primers and polymerase chain reaction (PCR) conditions to amplify four dinucleotide, one trinucleotide, and three tetranucleotide microsatellite DNA loci from the bobcat (Lynx rufus). The primers were tested on 22 individuals collected from a population located within southwestern Georgia (USA). The primer pairs developed in this study yielded an average of 7.4 alleles per locus (range four to 10), an average observed heterozygosity of 0.60 (range 0.40 to 0.76), and an average polymorphic information content of 0.70 (range 0.51 to 0.78).     

The mexR repressor of the mexAB-oprM multidrug efflux operon in Pseudomonas aeruginosa: characterization of mutations compromising activity

Mutations in mexR yield a multidrug resistance phenotype in nalB mutants of Pseudomonas aeruginosa as a result of derepression of the mexAB-oprM multidrug efflux operon. MexR produced by several nalB strains carried single amino acid changes that compromised MexR stability or its ability to dimerize. Changes at residues L95 and R21, however, produced a stable MexR protein capable of dimerization and, thus, likely compromised DNA binding.