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.     

Evaluation of a green laser pointer for flow cytometry.

Flow cytometers typically incorporate expensive lasers with high-quality (TEM00) output beam structure and very stable output power, significantly increasing system cost and power requirements. Red diode lasers minimize power consumption and cost, but limit fluorophore selection. Low-cost DPSS laser pointer modules could possibly offer increased wavelength selection but presumed emission instability has limited their use. A $160 DPSS 532 nm laser pointer module was first evaluated for noise characteristics and then used as the excitation light source in a custom-built flow cytometer for the analysis of fluorescent calibration and alignment microspheres. Eight of ten modules tested were very quiet (RMS noise < or = 0.6% between 0 and 5 MHz). With a quiet laser pointer module as the light source in a slow-flow system, fluorescence measurements from alignment microspheres produced CVs of about 3.3%. Furthermore, the use of extended transit times and < or =1 mW of laser power produced both baseline resolution of all 8 peaks in a set of Rainbow microspheres, and a detection limit of <20 phycoerythrin molecules per particle. Data collected with the transit time reduced to 25 micros (in the same instrument but at 2.4 mW laser output) demonstrated a detection limit of approximately 75 phycoerythrin molecules and CVs of about 2.7%. The performance, cost, size, and power consumption of the tested laser pointer module suggests that it may be suitable for use in conventional flow cytometry, particularly if it were coupled with cytometers that support extended transit times.     

K-way neural network graph partitioning with separator vertices

A neural network for partitioning graphs into any number of subgraphs using a k-way procedure is presented. The resulting neural network optimises all subgraphs so that they contain approximately the same number of vertices with the exception of a `separator' subgraph. The latter separates all the other subgraphs and is optimised to contain a minimum number of vertices. Expressions for the neuron link weights for such a network are derived analytically, and the recall mechanism of the mean field theorem neural network is used to obtain the graph partitioning. Applications focus on partitioning graphs associated with finite element meshes which, together with parallel domain decomposition solution methods, provide the motivation for this work. Received: 14 January 1998 / Accepted in revised form: 24 November 1998     

Unexpected ratio of allozyme expression in diploid and triploid individuals of the clonal hybrid fish Phoxinus eos-neogaeus.

Phoxinus eos-neogaeus, a North American freshwater fish, was formed by hybridization between P. neogaeus and P. eos. Individuals of P. eos-neogaeus express one allozyme of P. eos and one allozyme of P. neogaeus for enzymes for which the parental allozymes are distinctive. We performed densitometry on phosphoglucomutase (PGM) and one glucose-6-phosphate isomerase locus (GPI-A) separated by cellulose acetate electrophoresis to determine if the parental species' allozymes are expressed in proportion to the number of genomes present in diploid and triploid individuals, and if these enzymes are regulated separately in different tissues. In diploids, activity of the P. eos allozyme was greater than the P. neogaeus allozyme in eye, liver, and muscle but not in heart (one sample t-test, P = 0.05) for PGM. The activity of the P. eos GPI-A allozyme was significantly greater than the P. neogaeus allozyme in heart, eye and muscle but not in liver (one sample t-test, P = 0.05). The expected ratio of eos:neogaeus expression in triploid P. eos-neogaeus x eos individuals is 2:1. For PGM, the observed ratio of eos:neogaeus expression was not significantly different from 2:1 in all four tissues. The P. eos allozyme for GPI was expressed less than expected in all four tissues (one-sample t-test, P = 0.05). Thus, greater than expected expression of the P. eos allozyme was not observed in triploid individuals as it was in the diploids. These data show that PGM and GPI are regulated separately, and that regulation differs by tissue, and in fish of distinct ploidy levels. J. Exp. Zool. 284:663-674, 1999.     

A short-oligonucleotide microarray that allows improved detection of gastrointestinal tract microbial communities

Background  

The human gastrointestinal (GI) tract contains a diverse collection of bacteria, most of which are unculturable by conventional microbiological methods. Increasingly molecular profiling techniques are being employed to examine this complex microbial community. The purpose of this study was to develop a microarray technique based on 16S ribosomal gene sequences for rapidly monitoring the microbial population of the GI tract.     

Novel naphthoquinone and quinolinedione inhibitors of CDC25 phosphatase activity with antiproliferative properties

CDC25 phosphatases are considered as attractive targets for anti-cancer therapy. To date, quinone derivatives are among the most potent inhibitors of CDC25 phosphatase activity. We present in this paper the synthesis and the biological evaluation of new quinolinedione and naphthoquinone derivatives, containing carboxylic or malonic acids groups introduced to mimic the role of the phosphate moieties of Cyclin-Dependent Kinase complexes. The most efficient compounds show inhibitory activity against CDC25B with IC(50) values in the 10 microM range, and are cytotoxic against HeLa cells.     

A database of microsatellite genotypes for <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis>

A system for genotyping Saccharomyces cerevisiae is described based on a multiplex of ten microsatellite loci and the MAT locus. A database of genotypes has been developed for 246 yeast strains, including a large set of commercial wine yeasts, as well as 35 sequenced natural isolates currently being sequenced. The latter allow us, for the first time, to make direct comparisons of the relationship between DNA sequence data and microsatellite-based genotypes. The genotyping system provides a rapid and valuable system for strain identification as well as studying population genetics of S. cerevisiae.