Comparative Inactivation of Adenovirus Serotypes by UV Light Disinfection

The results of this study confirm that adenoviruses are the most resistant enteric viruses to inactivation by UV light and that adenovirus 40 appears to be the most resistant. The effect of freeze-thawing and storage in water may affect the sensitivity of some adenoviruses to inactivation by UV light.     

Sensitivity of Planktonic and Biofilm-Associated Salmonella spp. to Ionizing Radiation

Salmonella enterica forms biofilms that are relatively resistant to chemical sanitizing treatments. Ionizing radiation has been used to inactivate Salmonella on a variety of foods and contact surfaces, but the relative efficacy of the process against biofilm-associated cells versus free-living planktonic cells is not well documented. The radiation sensitivity of planktonic or biofilm-associated cells was determined for three food-borne-illness-associated isolates of Salmonella. Biofilms were formed on sterile glass slides in a coincubation apparatus, using inoculated tryptic soy broth, incubated at 37°C for 48 h. Resulting biofilms were 18 to 24 μm in height as determined by confocal scanning laser microscopy. The planktonic and biofilm cultures were gamma irradiated to doses of 0.0 (control), 0.5, 1.0, 1.5, 2.0 and 2.5 kGy. The D₁₀ value (the dose of radiation required to reduce a population by 1 log₁₀, or 90%) was calculated for each isolate-culture based on surviving populations at each radiation dose. The D₁₀ values of S. enterica serovar Anatum were not significantly (P < 0.05) different for biofilm-associated (0.645 kGy) and planktonic (0.677 kGy) cells. In contrast, the biofilm-associated cells of S. enterica serovar Stanley were significantly more sensitive to ionizing radiation than the respective planktonic cells, with D₁₀ values of 0.531 and 0.591 kGy, respectively. D₁₀ values of S. enterica serovar Enteritidis were similarly reduced for biofilm-associated (0.436 kGy) versus planktonic (0.535 kGy) cells. The antimicrobial efficacy of ionizing radiation is therefore preserved or enhanced in treatment of biofilm-associated bacteria.     

Correlation of Phenotype with the Genotype of Egg-Contaminating Salmonella enterica Serovar Enteritidis

The genotype of Salmonella enterica serovar Enteritidis was correlated with the phenotype using DNA-DNA microarray hybridization, ribotyping, and Phenotype MicroArray analysis to compare three strains that differed in colony morphology and phage type. No DNA hybridization differences were found between two phage type 13A (PT13A) strains that varied in biofilm formation; however, the ribotype patterns were different. Both PT13A strains had DNA sequences similar to that of bacteriophage Fels2, whereas the PT4 genome to which they were compared, as well as a PT4 field isolate, had a DNA sequence with some similarity to the bacteriophage ST64b sequence. Phenotype MicroArray analysis indicated that the two PT13A strains and the PT4 field isolate had similar respiratory activity profiles at 37°C. However, the wild-type S. enterica serovar Enteritidis PT13A strain grew significantly better in 20% more of the 1,920 conditions tested when it was assayed at 25°C than the biofilm-forming PT13A strain grew. Statistical analysis of the respiratory activity suggested that S. enterica serovar Enteritidis PT4 had a temperature-influenced dimorphic metabolism which at 25°C somewhat resembled the profile of the biofilm-forming PT13A strain and that at 37°C the metabolism was nearly identical to that of the wild-type PT13A strain. Although it is possible that lysogenic bacteriophage alter the balance of phage types on a farm either by lytic competition or by altering the metabolic processes of the host cell in subtle ways, the different physiologies of the S. enterica serovar Enteritidis strains correlated most closely with minor, rather than major, genomic changes. These results strongly suggest that the pandemic of egg-associated human salmonellosis that came into prominence in the 1980s is primarily an example of bacterial adaptive radiation that affects the safety of the food supply.     

Molecular Analysis of Human, Porcine, and Poultry Enterococcus faecium Isolates and Their erm(B) Genes

Fifty-nine erm(B)-positive Enterococcus faecium strains isolated from pigs, broilers, and humans were typed using multilocus sequence typing (MLST), and the coding sequence of the erm(B) gene was determined. Identical erm(B) gene sequences were detected in genetically unrelated isolates. Furthermore, genetically indistinguishable strains were found to contain different erm(B) alleles. This may suggest that horizontal exchange of the erm(B) gene between animal and human E. faecium strains or the existence of a common reservoir of erm(B) genes might be more important than direct transmission of resistant strains.     

Coherent phase microscopy in cell biology: visualization of metabolic states

Visualization of functional properties of individual cells and intracellular organelles still remains an experimental challenge in cell biology. The coherent phase microscopy (CPM) provides a convenient and non-invasive tool for imaging cells and intracellular organelles. In this work, we report results of statistical analysis of CPM images of cyanobacterial cells (Synechocystis sp. PCC 6803) and spores (Bacillus licheniformis). It has been shown that CPM images of cyanobacterial cells and spores are sensitive to variations of their metabolic states. We found a correlation between one of optical parameters of the CPM image (‘phase thicknesses’ Δh) and cell energization. It was demonstrated that the phase thickness Δh decreased after cell treatment with the uncoupler CCCP or inhibitors of electron transport (KCN or DCMU). Statistical analysis of distributions of parameter Δh and cell diameter d demonstrated that a decrease in the phase thickness Δh could not be attributed entirely to a decrease in geometrical sizes of cells. This finding demonstrates that the CPM technique may be a convenient tool for fast and non-invasive diagnosis of metabolic states of individual cells and intracellular organelles.     

Porous membranes for reconstitution of ion channels

Functional biological synthetic composite (BSC) membranes were made using phospholipids, biological membrane proteins and permeable synthetic supports or membranes. Lipid bilayers were formed on porous polycarbonate (PC), polyethylene terephthalate (PETE) and poly (l-lactic acid) (PLLA) membranes and in 10-100 μm laser-drilled pores in a 96-well plastic plate as measured by increased resistance or decreased currents. Bilayers in 50 μm and smaller pores were stable for up to 4 h as measured by resistance changes or a current after gramicidin D reconstitution. Biological membrane transport reconstitution was then carried out. Using vesicles containing Kv1.5 K⁺ channels, K⁺ currents and decreased resistance were measured across bilayers in 50 μm pores in the plastic plate and PLLA membranes, respectively, which were inhibited by compound B, a Kv1.5 K⁺ channel inhibitor. Functional reconstitution of Kv1.5 K⁺ channels was successful. Incorporation of membrane proteins in functional form in stable permeable membrane-supported lipid bilayers is a simple technology to create BSC membranes that mimic biological function which is readily adaptable for high throughput screening.     

Importance of glucose-6-phosphate dehydrogenase in taxol biosynthesis in <Emphasis Type="Italic">Taxus chinensis</Emphasis> cultures

The roles of glucose-6-phosphate dehydrogenase (G6PDH) in paclitaxel production were investigated in cell suspension cultures of Taxus chinensis. In the normal cultures, the trend of G6PDH activity was similar to that of cell growth. Addition of glutamate increased G6PDH activity, while dehydroepiandrosterone (DHEA) decreased G6PDH activity. In elicitor-treated cultures, cell growth was depressed, while G6PDH activity and taxol production were enhanced compared with the control. Glutamate recovered the depression of cell growth, and resulted in further increase in G6PDH activity and taxol production. Contrarily, DHEA exacerbated the depression of cell growth, and decreased G6PDH activity and taxol production induced by fungal elicítor. The results indicated that G6PDH played a critic role of taxol production by affecting cell viability.     

Late prehistoric wood use in an andean intermontane valley

Late Prehistoric Wood Use in an Andean Intermontane Valley. Economic Botany 59(4): 337-355, 2005. Data from carbonized wood remains from five late prehistoric sites (A.D. 1300–1530) in the Upper Mantaro Valley, Peru, are presented. The wood assemblage recovered is diverse. We illustrate and describe the twelve main morpho-types, one of which is more than likely to have been imported from the eastern slopes of the Andean mountains into the Mantaro Valley. The Inka conquest of the area created a change in socio-political power and also brought about a shift in the way wood species were utilized. From the Wanka II to the Inka occupations we find an increase in theBuddleja, Polylepis, Alnus, andColletia morpho-types: all of these species are reported as being cultivated by the Inka and possibly by pre-Inka inhabitants of the valley. A quantitative analysis shows higher amounts of wood in the elite dwellings of both the Wanka II and Wanka III times, suggesting a social aspect in the way this valuable Andean commodity was distributed and used.

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Résumé   El Uso de Madera Prehistorico Tardio en un Valle Andino. Fueron analizados los restos de madera provenientes de cinco sitios del período prehistorico tardio (1300–1530 d.C.) del Alto Valle Mantaro, Perú. La asamblea de moderns era muy variada Ilutramos y describimos las doce categorías taxonómicas prinicipales, una de las cuales probablamente fue importada desde las cuestas orientales de los Andes. La conquista Inkaica de la región efectuó un cambio de énfasis en los morfotipos de madera usados, con un aumento deBuddleja, Polylepis,Alnus, yColletia. Un análisis cuantitativo muestra una concentracion de maderas en las habitaciones de la clase élite, sugeriendo un aspecto social en el uso de la madera.

     

Phylogenetics of New World Astragalus: Screening of novel nuclear loci for the reconstruction of phylogenies at low taxonomic levels

This study explores methods to use information gathered from genomics technology to understand evolutionary relationships in the hyperdiverse legume group Neo-Astragalus. These species inhabit deserts and mountains of North and South America, and even though the monophyly of the group is well established, relationships within it are still poorly understood. Plastid genes, commonly used to infer phylogenies in plants, are usually not useful for closely related taxa because of low levels of genetic variation. TheMedicago truncatula genome project provided a suite of candidate nuclear loci with high levels of variation that might prove suitable for low-level phylogenetics. This paper reports the development of methods for screening a large number of these nuclear loci, and detailed analysis of four of them. Four different patterns of phylogenetic diversification occur in the loci sampled from these genomes ofAstragalus species. One locus (CNGC4) was single copy and could be directly used in phylogenetic analyses. Two loci (ARG10 and FENR) showed patterns strongly suggestive of duplication events in some taxa, and one locus (tRALS) has apparently undergone a cryptic duplication, making it very difficult to diagnose. Potential methods for using the information provided by these loci are discussed.