Survival and transport of bacteria in egg washwater.

An evaluation of methods for monitoring the quality of water used to wash eggs at grading stations was undertaken to improve maintenance of bacterial viability during overnight sample transport. Bacterial content of samples at analysis would then better reflect conditions at the time eggs were washed. The interactive effects of temperature and the highly alkaline water conditions upon viability were the subjects of this study. Nine transport methods were examined for their efficacy in recovering total and coliform bacteria from recycled water used to wash eggs, and these were compared with samples analyzed at two commercial egg grading stations. Samples were shipped under test to the laboratory for analysis the following day. The survival of Staphylococcus aureus and Escherichia coli was also examined, but in a synthetic washwater matrix under various combinations of temperature (6 to 32 degrees C) and pH (9.5 to 10.5) to determine whether there was likely to be a different response to variations in transport treatment among gram-positive and -negative bacteria. S. aureus was much more resistant to the lethal effects of high pH and moderate temperature than E. coli. These results indicated that samples of high pH should be held (transported) at less than or equal to 13 degrees C to optimize bacterial survival. Considering cost, ease of manipulation, and the ability to protect both coliforms and the bacterial population as a whole, the method of choice for transport of industrial samples was the direct addition of washwater to containers in which powdered KH2PO4 and Na2S2O3 had been placed to yield final concentrations, when dissolved, of 0.2 and 0.05% (wt/vol), respectively.     

Enumeration of Thiobacilli within pH-Neutral and Acidic Mine Tailings and Their Role in the Development of Secondary Mineral Soil

The Lemoine tailings of Chibougamau, Quebec, Canada, were deposited as a pH-neutral mineral conglomerate consisting of aluminum-silicates, iron-aluminum-silicates, pyrite, chalcopyrite, and sphalerite. These tailings are colonized by an active population of Thiobacillus ferrooxidans which is localized to an acid zone occupying 40% of the tailings' surface. This population peaked at 7 × 10⁸ most probable number per gram of tailings during July and August 1990 and extended to a depth of 40 cm from the surface. Examination of samples over this depth profile by transmission electron microscopy and electron dispersive spectroscopy revealed a microbially mediated mineral transition from sulfides (below 40 cm) to chlorides and phosphates (at the surface). Silicate minerals were unaltered by microbial action. Transmission electron microscopy showed a tight association between Thiobacillus species and the sulfide minerals, which helps account for their prominence in tailings environments. Accurate enumeration of T. ferrooxidans from tailings required the disruption of their bonding to the mineral interface. Vortexing of a 10% aqueous suspension of the tailings material prior to most-probable-number analysis best facilitated this release. Even though heavy metals were highly mobile under acidic conditions at the Lemoine tailings, it was evident by transmission electron microscopy and electron dispersive spectroscopy that they were being immobilized as bona fide fine-grain minerals containing iron, copper, chlorine, phosphorus, and oxygen on bacterial surfaces and exopolymers. This biomineralization increased with increasing bacterial numbers and was most evident in the upper 3 cm of the acidic zone.     

Examination of Lipopolysaccharide (O-Antigen) Populations of Thiobacillus ferrooxidans from Two Mine Tailings

Net acid-generating capacities of 39.74 kg of H₂SO₄ per ton (ca. 0.05 kg/kg) (pH 2.68) for the Lemoine copper mine tailings (closed ca. 8 years ago; located 40 km west of Chibougamau, Quebec, Canada) and 16.07 kg of H₂SO₄ per ton (ca. 0.02 kg/kg) (pH 3.01) for the Copper Rand tailings (in current use and 50 km distant [east] from those of Lemoine) demonstrate that these sulfide tailings can support populations of acidophilic thiobacilli. Oxidized regions in both tailings environments were readily visible, were extremely acidic (Lemoine, pH 2.36; Copper Rand, pH 3.07), and provided natural isolates for our study. A 10% (wt/vol) oxalic acid treatment, which solubilizes both ferric sulfate and ferric hydroxide precipitates (B. Ramsay, J. Ramsay, M. deTremblay, and C. Chavarie, Geomicrobiol. J. 6:171-177, 1988), enabled the recovery of intact bacterial cells from the tailings material and from liquid synthetic medium for lipopolysaccharide analysis. No viable cells could be cultured after this oxalic acid treatment. Sodium dodecyl sulfate-polyacrylamide gel electro-phoretic profiles of lipopolysaccharides extracted from the Lemoine tailings were complex, indicating a heterogeneous population of Thiobacillus ferrooxidans. Six T. ferrooxidans subspecies as identified by lipopolysaccharide analysis (i.e., lipopolysaccharide chemotypes) were eventually isolated from a total of 112 cultures from the Lemoine tailings. Using the same isolate and lipopolysaccharide typing techniques, we identified only a single lipopolysaccharide chemotype from 20 cultures of T. ferrooxidans isolated from the Copper Rand tailings. This homogeneity of lipopolysaccharide chemotype was much different from what was found for the older Lemoine tailings and may reflect a progressive lipopolysaccharide heterogeneity of Thiobacillus isolates as tailings leach and age.     

Characterization of novel, phenol-soluble polypeptides which confer rigidity to the sheath of Methanospirillum hungatei GP1.

Treatment of the Methanospirillum hungatei GP1 sheath with 90% (wt/vol) phenol resulted in the solubilization of a novel phenol-soluble group of polypeptides. These polypeptides were purified by the removal of insoluble material by ultracentrifugation and represented approximately 19% of the mass of the sheath. The phenol-insoluble material resembled untreated sheath but had lost its rigidity and cylindrical form. Recombination of phenol-soluble and phenol-insoluble fractions by dialysis to remove phenol resulted in cylindrical reassembly products. Although bona fide sheath (complete with the 2.8-nm lattice) was not produced, a role for the phenol-soluble polypeptides in the maintenance of sheath rigidity is implied. The phenol-soluble polypeptides have limited surface exposure as detected by antibodies on intact sheath; therefore, they are not responsible for the 2.8-nm repeat occurring on the outer face of the sheath. However, longitudinal and transverse linear labeling by protein A-colloidal gold on the outer and inner faces, respectively, occurred with monoclonal antibodies specific to the phenol-soluble polypeptides. Restricted surface exposure of phenol-soluble polypeptides on the sheath highlighted molecular defects in sheath architecture. These lattice faults may indicate sites of sheath growth to accommodate cell growth or division (longitudinal immunogold label) and filament division (transverse immunogold label). The identification of a second group of polypeptides within the infrastructure of the sheath suggests that the sheath is a trilaminar structure in which phenol-soluble polypeptides are sandwiched between sodium dodecyl sulfate-beta-mercaptoethanol-EDTA-soluble polypeptides (G. Southam and T. J. Beveridge, J. Bacteriol. 173:6213-6222, 1991) (phenol-insoluble material).     

Effect of Metalaxyl on the incidence and severity of Pearl millet downy mildew disease in Northern Nigeria

Pearl millet downy mildew (DM) incidence, severity and yield losses of two pearl millet varieties (local and improved) due to the disease were determined in the field. Significant differences in the disease incidence and severity were recorded in the plots sown with metalaxyl-treated seeds and those sown with non-treated seeds, indicating the efficacy of the fungicide on the fungus. Yield losses due to non-treatment of seeds with metalaxyl was 40.88 and 45.39% in a local variety and 43.00 and 18.60% in an improved variety in the 2000 and 2001 cropping seasons respectively. Significant differences between plots sown with metalaxyl-treated and those sown with non-treated seeds were obtained for other yield components such as 1000-grains weight, panicle length and weight.     

Monitoring cancer prognosis,diagnosis and treatment efficacy using metabolomics and lipidomics

Introduction

Cellular metabolism is altered during cancer initiation and progression, which allows cancer cells to increase anabolic synthesis, avoid apoptosis and adapt to low nutrient and oxygen availability. The metabolic nature of cancer enables patient cancer status to be monitored by metabolomics and lipidomics. Additionally, monitoring metabolic status of patients or biological models can be used to greater understand the action of anticancer therapeutics.

Objectives

Discuss how metabolomics and lipidomics can be used to (i) identify metabolic biomarkers of cancer and (ii) understand the mechanism-of-action of anticancer therapies. Discuss considerations that can maximize the clinical value of metabolic cancer biomarkers including case–control, prognostic and longitudinal study designs.

Methods

A literature search of the current relevant primary research was performed.

Results

Metabolomics and lipidomics can identify metabolic signatures that associate with cancer diagnosis, prognosis and disease progression. Discriminatory metabolites were most commonly linked to lipid or energy metabolism. Case–control studies outnumbered prognostic and longitudinal approaches. Prognostic studies were able to correlate metabolic features with future cancer risk, whereas longitudinal studies were most effective for studying cancer progression. Metabolomics and lipidomics can help to understand the mechanism-of-action of anticancer therapeutics and mechanisms of drug resistance.

Conclusion

Metabolomics and lipidomics can be used to identify biomarkers associated with cancer and to better understand anticancer therapies.

     

Gene expression and the evolution of phenotypic diversity in social wasps

Background  

Organisms are capable of developing different phenotypes by altering the genes they express. This phenotypic plasticity provides a means for species to respond effectively to environmental conditions. One of the most dramatic examples of phenotypic plasticity occurs in the highly social hymenopteran insects (ants, social bees, and social wasps), where distinct castes and sexes all arise from the same genes. To elucidate how variation in patterns of gene expression affects phenotypic variation, we conducted a study to simultaneously address the influence of developmental stage, sex, and caste on patterns of gene expression in Vespula wasps. Furthermore, we compared the patterns found in this species to those found in other taxa in order to investigate how variation in gene expression leads to phenotypic evolution.     

Linkage and association analysis of angiotensin I-converting enzyme (ACE)-gene polymorphisms with ACE concentration and blood pressure

Considerable effort has been expended to determine whether the gene for angiotensin I-converting enzyme (ACE) confers susceptibility to cardiovascular disease. In this study, we genotyped 13 polymorphisms in the ACE gene in 1,343 Nigerians from 332 families. To localize the genetic effect, we first performed linkage and association analysis of all the markers with ACE concentration. In multipoint variance-component analysis, this region was strongly linked to ACE concentration (maximum LOD score 7.5). Likewise, most of the polymorphisms in the ACE gene were significantly associated with ACE (P<.0013). The two most highly associated polymorphisms, ACE4 and ACE8, accounted for 6% and 19% of the variance in ACE, respectively. A two-locus additive model with an additive x additive interaction of these polymorphisms explained most of the ACE variation associated with this region. We next analyzed the relationship between these two polymorphisms (ACE4 and ACE8) and blood pressure (BP). Although no evidence of linkage was detected, significant association was found for both systolic and diastolic BP when a two-locus additive model developed for ACE concentration was used. Further analyses demonstrated that an epistasis model provided the best fit to the BP variation. In conclusion, we found that the two polymorphisms explaining the greatest variation in ACE concentration are significantly associated with BP, through interaction, in this African population sample. Our study also demonstrates that greater statistical power can be anticipated with association analysis versus linkage, when markers in strong linkage disequilibrium with a trait locus have been identified. Furthermore, allelic interaction may play an important role in the dissection of complex traits such as BP.