Expression, purification and structural analysis of the Pyrococcus abyssi RNA binding protein PAB1135

Background

Epistatic interactions of multiple single nucleotide polymorphisms (SNPs) are now believed to affect individual susceptibility to common diseases. The detection of such interactions, however, is a challenging task in large scale association studies. Ant colony optimization (ACO) algorithms have been shown to be useful in detecting epistatic interactions.

Findings

AntEpiSeeker, a new two-stage ant colony optimization algorithm, has been developed for detecting epistasis in a case-control design. Based on some practical epistatic models, AntEpiSeeker has performed very well.

Conclusions

AntEpiSeeker is a powerful and efficient tool for large-scale association studies and can be downloaded from http://nce.ads.uga.edu/~romdhane/AntEpiSeeker/index.html.     

Comparison of techniques for the measurement of skin temperature during exercise in a hot,humid environment

Exercising or working in a hot, humid environment can results in the onset of heat-related illness when an individual''s temperature is not carefully monitored. The purpose of the present study was to compare three techniques (data loggers, thermal imaging, and wired electrodes) for the measurement of peripheral (bicep) and central (abdominal) skin temperature. Young men and women (N = 30) were recruited to complete the present study. The three skin temperature measurements were made at 0 and every 10-min during 40-min (60% VO₂max) of cycling in a hot (39±2°C), humid (45±5% RH) environment. Data was statistically analyzed using the Bland-Altman method and correlation analysis. For abdominal skin temperature, the Bland-Altman limits of agreement indicated that data loggers (1.5) were a better index of wired than was thermal imaging (3.5), For the bicep skin temperature the limits of agreement was similar between data loggers (1.9) and thermal (1.9), suggesting the both were suitable measurements. We also found that when skin temperature exceeded 35°C, we observed progressively better prediction between data loggers, thermal imaging, and wired skin sensors. This report describes the potential for the use of data loggers and thermal imaging to be used as alternative measures of skin temperature in exercising, human subjects.     

Human mesenchymal stem cells are resistant to cytotoxic and genotoxic effects of cisplatin in vitro

Mesenchymal stem cells (MSCs) are known for their important properties involving multilineage differentiation potential., trophic factor secretion and localization along various organs and tissues. On the dark side, MSCs play a distinguished role in tumor microenvironments by differentiating into tumor-associated fibroblasts or supporting tumor growth via distinct mechanisms. Cisplatin (CIS) is a drug widely applied in the treatment of a large number of cancers and is known for its cytotoxic and genotoxic effects, both in vitro and in vivo. Here we assessed the effects of CIS on MSCs and the ovarian cancer cell line OVCAR-3, by MTT and comet assays. Our results demonstrated the resistance of MSCs to cell death and DNA damage induction by CIS, which was not observed when OVCAR-3 cells were exposed to this drug.     

Binding and internalization of native gonadoliberin (GnRH) by anterior pituitary gonadotrophs of the rat

Summary To identify anterior pituitary cell types containing GnRH binding sites and to study the internalization process of this peptide by target cells under physiological conditions, autoradiography was performed on rat anterior pituitaries removed at specific time intervals (2–60 min) after intravenous injection of mono-radioiodinated ¹²⁵I-GnRH into intact males. At electron-microscopic level, gonadotrophs and lactotrophs appeared to contain silver grains. Concomitant administration of an excess of unlabeled GnRH with the radioiodinated hormone prevented this localization indicating the specificity of the reaction. The time-course study in gonadotrophs showed that 2 min after injection silver grains could be found over the plasma membrane, secretory granules and nuclear membrane. Similar results were observed 5 and 15 min after injection. Extensive label was observed over the nucleus and nuclear membrane 15 to 60 min after injection. The injection of a radioiodinated GnRH agonist [D-Trp⁶, Pro⁹ (Net), DesGly¹⁰]-GnRH produced comparable results. In contrast, the injection of ¹²⁵I-[D-pGlu¹, D-Phe², Trp^3,6]-GnRH, an antagonist of GnRH, produced positive labeling only at the plasma membrane without internalization. These results indicate that, after binding with receptors on the plasma membrane, GnRH is rapidly internalized, accumulating in secretory granules, and localizing over the nuclear membrane and later, in the nucleus. Association of radioactivity with secretory granules could be related to a specific action of GnRH at this level or to receptor recycling, and presence of label in the nucleus may be related to stimulation of neosynthesis of LH and GnRH receptors.     

Proteomic profile of culture filtrate from the Brazilian vaccine strain <Emphasis Type="Italic">Mycobacterium bovis</Emphasis> BCG Moreau compared to <Emphasis Type="Italic">M. bovis</Emphasis> BCG Pasteur

Background  

Bacille Calmette-Guerin (BCG) is currently the only available vaccine against tuberculosis (TB) and comprises a heterogeneous family of sub-strains with genotypic and phenotypic differences. The World Health Organization (WHO) affirms that the characterization of BCG sub-strains, both on genomic and proteomic levels, is crucial for a better comprehension of the vaccine. In addition, these studies can contribute in the development of a more efficient vaccine against TB. Here, we combine two-dimensional electrophoresis (2DE) and mass spectrometry to analyse the proteomic profile of culture filtrate proteins (CFPs) from M. bovis BCG Moreau, the Brazilian vaccine strain, comparing it to that of BCG Pasteur. CFPs are considered of great importance given their dominant immunogenicity and role in pathogenesis, being available for interaction with host cells since early infection.     

Recombinagenic and mutagenic activities of fluoroquinolones in Drosophila melanogaster

Fluoroquinolones are widely used in human and in veterinary medicine due to their broad-spectrum antibacterial activity. They act by inhibiting type II DNA topoisomerases (gyrase and topoisomerase IV). Because of the sequence homology between prokaryotic and eukaryotic topoisomerases II, fluoroquinolones can pose a hazard to eukaryotic cells. However, published information concerning the genotoxic profiles of these drugs in vivo is sparse and inconsistent. We have assessed the activities of three fluoroquinolones, ciprofloxacin, enrofloxacin and norfloxacin, in the Drosophila melanogaster Somatic Mutation and Recombination Test (SMART) and measured their mutagenic and recombinagenic potentials. Norfloxacin was non-genotoxic. Ciprofloxacin and enrofloxacin induced significant increases in spot frequencies in trans-heterozygous flies. To test the roles of somatic recombination and mutation in the observed genotoxicity, balancer-heterozygous flies were also analyzed. Ciprofloxacin and enrofloxacin were preferential inducers of homologous recombination in proliferative cells, an event linked to loss of heterozygosity.     

Molecular models of NS3 protease variants of the Hepatitis C virus

Background  

Hepatitis C virus (HCV) currently infects approximately three percent of the world population. In view of the lack of vaccines against HCV, there is an urgent need for an efficient treatment of the disease by an effective antiviral drug. Rational drug design has not been the primary way for discovering major therapeutics. Nevertheless, there are reports of success in the development of inhibitor using a structure-based approach. One of the possible targets for drug development against HCV is the NS3 protease variants. Based on the three-dimensional structure of these variants we expect to identify new NS3 protease inhibitors. In order to speed up the modeling process all NS3 protease variant models were generated in a Beowulf cluster. The potential of the structural bioinformatics for development of new antiviral drugs is discussed.