Silver-Zinc Redox-Coupled Electroceutical Wound Dressing Disrupts Bacterial Biofilm

Pseudomonas aeruginosa biofilm is commonly associated with chronic wound infection. A FDA approved wireless electroceutical dressing (WED), which in the presence of conductive wound exudate gets activated to generate electric field (0.3–0.9V), was investigated for its anti-biofilm properties. Growth of pathogenic P. aeruginosa strain PAO1 in LB media was markedly arrested in the presence of the WED. Scanning electron microscopy demonstrated that WED markedly disrupted biofilm integrity in a setting where silver dressing was ineffective. Biofilm thickness and number of live bacterial cells were decreased in the presence of WED. Quorum sensing genes lasR and rhlR and activity of electric field sensitive enzyme, glycerol-3-phosphate dehydrogenase was also repressed by WED. This work provides first electron paramagnetic resonance spectroscopy evidence demonstrating that WED serves as a spontaneous source of reactive oxygen species. Redox-sensitive multidrug efflux systems mexAB and mexEF were repressed by WED. Taken together, these observations provide first evidence supporting the anti-biofilm properties of WED.     

Structural Model of the Bilitranslocase Transmembrane Domain Supported by NMR and FRET Data

We present a 3D model of the four transmembrane (TM) helical regions of bilitranslocase (BTL), a structurally uncharacterized protein that transports organic anions across the cell membrane. The model was computed by considering helix-helix interactions as primary constraints, using Monte Carlo simulations. The interactions between the TM2 and TM3 segments have been confirmed by Förster resonance energy transfer (FRET) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy, increasing our confidence in the model. Several insights into the BTL transport mechanism were obtained by analyzing the model. For example, the observed cis-trans Leu-Pro peptide bond isomerization in the TM3 fragment may indicate a key conformational change during anion transport by BTL. Our structural model of BTL may facilitate further studies, including drug discovery.     

Differential Inhibition by Allylsulfide of Nitrification and Methane Oxidation in Freshwater Sediment

Addition of nitrapyrin, allylthiourea, C(inf2)H(inf2), and CH(inf3)F to freshwater sediment slurries inhibited CH(inf4) oxidation and nitrification to similar extents. Dicyandiamide and allylsulfide were less inhibitory for CH(inf4) oxidation than for nitrification. Allylsulfide was the most potent inhibitor of nitrification, and the estimated 50% inhibitory concentrations for this process and CH(inf4) oxidation were 0.2 and 121 (mu)M, respectively. At a concentration of 2 (mu)M allylsulfide, growth and CH(inf4) oxidation activity of Methylosinus trichosporium OB3b were not inhibited. Allylsulfide at 200 (mu)M inhibited the growth of M. trichosporium by approximately 50% but did not inhibit CH(inf4) oxidation activity. Nitrite production by cells of M. trichosporium was not significantly affected by allylsulfide, except at a concentration of 2 mM, when growth and CH(inf4) oxidation were also inhibited by about 50%. Methane monooxygenase activity present in soluble fractions of M. trichosporium was not inhibited significantly by allylsulfide at either 200 (mu)M or 2 mM. These results suggest that the partial inhibition of CH(inf4) oxidation in sediment slurries by high allylsulfide concentrations may be caused by an inhibition of the growth of methanotrophs rather than an inhibition of methane monooxygenase activity specifically. We conclude that allylsulfide is a promising tool for the study of interactions of methanotrophs and nitrifiers in N cycling and CH(inf4) turnover in natural systems.     

E-cadherin is a tumour/invasion suppressor gene mutated in human lobular breast cancers.

Compelling experimental evidence exists for a potent invasion suppressor role of the cell-cell adhesion molecule E-cadherin. In addition, a tumour suppressor effect has been suggested for E-cadherin. In human cancers, partial or complete loss of E-cadherin expression correlates with malignancy. To investigate the molecular basis for this altered expression we developed a comprehensive PCR/SSCP mutation screen for the human E-cadherin gene. For 49 breast cancer patients the occurrence of tumour-specific mutations in the E-cadherin gene was examined. No relevant DNA changes were encountered in any of 42 infiltrative ductal or medullary breast carcinoma samples. In contrast, four out of seven infiltrative lobular breast carcinomas harboured protein truncation mutations (three nonsense and one frameshift) in the extracellular part of the E-cadherin protein. Each of the four lobular carcinomas with E-cadherin mutations showed tumour-specific loss of heterozygosity of chromosomal region 16q22.1 containing the E-cadherin locus. In compliance with this, no E-cadherin expression was detectable by immunohistochemistry in these four tumours. These findings offer a molecular explanation for the typical scattered tumour cell growth in infiltrative lobular breast cancer.     

Sable and umbrous mice

Summary An umbrous gene in the house mouse is described which is transmitted in crosses as a simple dominant. The same gene is capable of engendering a sable phenotype with yellow and an umbrous-agouti with white-bellied agouti. It assorts independently of the agouti locus, with which it was specifically tested, and probably of sex. The manifestation of the gene is briefly contrasted with other known cases of umbrous heredity.     

Detection of quantitative trait loci for growth and fatness in pigs

A quantitative trait locus (QTL) analysis of growth and fatness data from a three-generation experimental cross between Meishan (MS) and Large White (LW) pig breeds is presented. Six boars and 23 F1 sows, the progeny of six LW boars and six MS sows, produced 530 F2 males and 573 F2 females. Nine growth traits, i.e. body weight at birth and at 3, 10, 13, 17 and 22 weeks of age, average daily gain from birth to 3 weeks, from 3 to 10 weeks and from 10 to 22 weeks of age, as well as backfat thickness at 13, 17 and 22 weeks of age and at 40 and 60 kg live weight were analysed. Animals were typed for a total of 137 markers covering the entire porcine genome. Analyses were performed using two interval mapping methods: a line-cross (LC) regression method where founder lines were assumed to be fixed for different QTL alleles and a half-/full-sib (HFS) maximum likelihood method where allele substitution effects were estimated within each half-/full-sib family. Both methods revealed highly significant gene effects for growth on chromosomes 1, 4 and 7 and for backfat thickness on chromosomes 1, 4, 5, 7 and X, and significant gene effects on chromosome 6 for growth and backfat thickness. Suggestive QTLs were also revealed by both methods on chromosomes 2 and 3 for growth and 2 for backfat thickness. Significant gene effects were detected for growth on chromosomes 11, 13, 14, 16 and 18 and for backfat thickness on chromosome 8, 10, 13 and 14. LW alleles were associated with high growth rate and low backfat thickness, except for those of chromosome 7 and to a lesser extent early-growth alleles on chromosomes 1 and 2 and backfat thickness alleles on chromosome 6.     

Plasma B-esterase activities in European raptors

B-esterases are serine hydrolases composed of cholinesterases, including acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), and carboxylesterase (CbE). These esterases, found in blood plasma, are inhibited by organophosphorus (OP) and carbamate (CB) insecticides and can be used as nondestructive biomarkers of exposure to anticholinesterase insecticides. Furthermore, B-esterases are involved in detoxification of these insecticides. In order to establish the level of these enzymes and to have reference values for their normal activities, total plasma cholinesterase (ChE), AChE and BChE activities, and plasma CbE activity were determined in 729 European raptors representing 20 species, four families, and two orders. The diurnal families of the Falconiforme order were represented by Accipitridae and Falconidae and the nocturnal families of the Strigiforme order by Tytonidae and Strigidae. Intraspecies differences in cholinesterase activities according to sex and/or age were investigated in buzzards (Buteo buteo), sparrowhawks (Accipiter nisus), kestrels (Falco tinnunculus), barn owls (Tyto alba), and tawny owls (Strix aluco). Sex-related differences affecting ChE and AChE activities were observed in young kestrels (2-3-mo-old) and age-related differences in kestrels (ChE and AChE), sparrowhawks (AChE), and tawny owls (ChE, AChE, and BChE). The interspecies analysis yielded a negative correlation between ChE activity and body mass taking into account the relative contribution of AChE and BChE to ChE activity, with the exception of the honey buzzard (Pernis apivorus). The lowest ChE activities were found in the two largest species, Bonelli's eagle (Hieraaetus fasciatus) and Egyptian vulture (Neophron percnopterus) belonging to the Accipitridae family. The highest ChE activities were found in the relatively small species belonging to the Tytonidae and Strigidae families and in honey buzzard of the Accipitridae family. Species of the Accipitridae, Tytonidae, and Strigidae families were characterized by a BChE contribution that dominated the total ChE activity, while in the species of the Falconidae family, AChE activity dominated. With the exception of the barn owl, CbE activity (eserine-insensitive alpha-naphthyl acetate esterase [alpha-NAE] activity) in all species was almost absent or very low. The values obtained in this study for ChE, AChE, and BChE activities and the AChE:BChE ratios for buzzard, kestrel, barn owl, and tawny owl provide a good estimate of the normal values in free-living individuals of these European species. They can be used as a baseline to evaluate the effect of anticholinesterase insecticides in the field.