Digital Commons Network^™

Towards A Systems Approach To Understanding Plant Cell Walls, Chris R. Somerville, Stefan Bauer, Ginger Brininstool, Michelle Facette, Thorsten Hamann, Jennifer Milne, Erin Osborne, Alex Paradez, Staffan Persson, Ted K. Raab, Sonja Vorwerk, Heather Youngs

Ted K. Raab

One of the defining features of plants is a body plan based on the physical properties of cell walls. Structural analyses of the polysaccharide components, combined with highresolution imaging, have provided the basis for much of the current understanding of cell walls. The application of genetic methods has begun to provide new insights into how walls are made, how they are controlled, and how they function. However, progress in integrating biophysical, developmental, and genetic information into a useful model will require a system-based approach.

In Vivo Dose-Response Of Insects To Hz-2v Infection, John P. Burand, Christopher P. Rallis

John Burand

Background Hz-2V infection of female Helicoverpa zea moths is manifested as insects that are either sterile "agonadal" individuals with malformed reproductive tissues or fertile asymptomatic carriers which are capable of transmitting virus on to their progeny. Virus infected progeny arising from eggs laid by asymptomatic carrier females may themselves be either sterile agonadals or asymptomatic carriers. Results By injecting virus into female moths, a correlation was established between virus doses administered to the females and the levels of resulting asymptomatic and sterile progeny. Conclusions The results of these experiments indicate that high virus doses produced a higher level of agonadal …

Allele Specific Synthetic Lethality Between Pric And Dnaats Alleles At The Permissive Temperature Of 30°C In E. Coli K-12, Steven Sandler, Tania Hinds

Steven Sandler

Background DnaA is an essential protein in the regulation and initiation of DNA replication in many bacteria. It forms a protein-DNA complex at oriC to which DnaC loads DnaB. DNA replication forks initiated at oriC by DnaA can collapse on route to the terminus for a variety of reasons. PriA, PriB, PriC, DnaT, Rep and DnaC form multiple pathways to restart repaired replication forks. DnaC809 and dnaC809,820 are suppressors of priA2::kan mutant phenotypes. The former requires PriC and Rep while the latter is independent of them. RnhA339::cat mutations allow DnaA-independent initiation of DNA replication. Results It is shown herein that …

Dna Microarray Analysis Of Nitrogen Fixation And Fe(Iii) Reduction In Geobacter Sulfurreducens, Jennifer Webster, Barbara A. Methé, Kelly P. Nevin, Jessica E. Butler, Derek Lovley

Derek Lovley

A DNA microarray representing the genome of Geobacter sulfurreducens was constructed for use in global gene expression profiling of cells under steady-state conditions with acetate as the electron donor and Fe(III) or fumarate as the electron acceptor. Reproducible differences in transcript levels were also observed in comparisons between cells grown with ammonia and those fixing atmospheric nitrogen. There was a high correlation between changes in transcript levels determined with microarray analyses and an evaluation of a subset of the genome with quantitative PCR. As expected, cells required to fix nitrogen had higher levels of transcripts of genes associated with nitrogen …

Dissociation Of The Hepatic Phenotype From Hnf4 And Hnf1x Expression, Gary A. Bulla, David M. Kraus

Gary A. Bulla

Dedifferentiated cells have served as tools to understand the molecular consequences of the loss of tissue-specific pathways. Here we report the characterization of one of these cell lines, M29, which lacks the liver-enriched HNF4-HNF1x pathway, in order to determine if this class of variant cell lines could provide additional information regarding requirements for tissue-type expression. We report that although the liver-specific x1-antitrypsin (a1AT) gene remains silent despite reactivation of the HNF4/HNF1x pathway in the M29 cells, the frequency of activation of an integrated x1AT-APRT transgene is increased 1000-fold in response to these transcription factors. The human x1AT locus (introduced via …

Mutations In Pmr5 Result In Powdery Mildew Resistance And Altered Cell Wall Composition, John P. Vogel, Ted K. Raab, Chris R. Somerville, Shauna C. Somerville

Ted K. Raab

Powdery mildews and other obligate biotrophic pathogens are highly adapted to their hosts and often show limited host ranges. One facet of such host specialization is likely to be penetration of the host cell wall, a major barrier to infection. A mutation in the pmr5 gene rendered Arabidopsis resistant to the powdery mildew species Erysiphe cichoracearum and Erysiphe orontii, but not to the unrelated pathogens Pseudomonas syringae or Peronospora parasitica. PMR5 belongs to a large family of plant-specific genes of unknown function. pmr5-mediated resistance did not require signaling through either the salicylic acid or jasmonic acid/ ethylene defense pathways, suggesting …

Meeting The Scientific Needs Of Ecological Risk Assessment In A Regulatory Context, Steven P. Bradbury, Tom C. Feitel, Cornelis J. Van Leeuwen

Steven P. Bradbury

During the past decade, the field of ecological risk assessment has progressed considerably. Advances have come from such international bodies as the Organisation for Economic Co-operation and Development (OECD), the World Health Organisation (WHO), the European and Mediterranean Plant Protection Organisation (EPPO), and the European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC) (1–8). Risk assessments have played a critical role in the development of various regulations within the European Commission (EC) as well as in other parts of the world, including the United States, Canada, and Japan (9–17). But scientists and regulators are faced with three significant challenges: streamlining …

In Situ Expression Of Nigd In Geobacteraceae In Subsurface Sediments, Dawn E. Holmes, Kelly P. Nevin, Derek Lovley

Kelly Nevin

In order to determine whether the metabolic state of Geobacteraceae involved in bioremediation of subsurface sediments might be inferred from levels of mRNA for key genes, in situ expression of nifD, a highly conserved gene involved in nitrogen fixation, was investigated. When Geobacter sulfurreducens was grown without a source of fixed nitrogen in chemostats with acetate provided as the limiting electron donor and Fe(III) as the electron acceptor, levels of nifD transcripts were 4 to 5 orders of magnitude higher than in chemostat cultures provided with ammonium. In contrast, the number of transcripts of recA and the 16S rRNA gene …

Biomimetic Actuators: Where Technology And Cell Biology Merge [Review Article], Michael Knoblauch, Winfried Peters

Winfried S. Peters

Comments On Eusopondis And Proctoporus (Squamata: Gymnophthalmidae) From Peru, With The Description Of Three New Species And A Key To The Peruvian Species, Edgar Lehr, Gunther Kohler

Edgar Lehr

We describe two new species of Proctoporus and a new species of Euspondylus (all from central Peru, Departamento de Huanuco, 2545 to 3010 m elevation). The new species are distinguished from all species presently assigned to Proctoporus and Euspondylus by unique characteristics of pholidosis, morphometrics, and color pattern. A key to the Peruvian species of Proctoporus and Euspondylus is provided. The current allocation of species to Proctoporus and Euspondylus may not reflect the phylogenetic relationships of the species under consideration. Based on the available data there appears to be no evidence to justify the separation of these genera. However, because …

Photo- And Electropatterning Of Hydrogel-Encapsulated Living Cell Arrays, Dirk Albrecht, Valerie Tsang, Robert Sah, Sangeeta Bhatia

Dirk R. Albrecht

Living cells have the potential to serve as sensors, naturally integrating the response to stimuli to generate predictions about cell fate (e.g., differentiation, migration, proliferation, apoptosis). Miniaturized arrays of living cells further offer the capability to interrogate many cells in parallel and thereby enable high-throughput and/or combinatorial assays. However, the interface between living cells and synthetic chip platforms is a critical one wherein the cellular phenotype must be preserved to generate useful signals. While some cell types retain tissue-specific features on a flat (2-D) surface, it has become increasingly apparent that a 3-D physical environment will be required for others. …

Lateral Hypothalamic Signaling Mechanisms Underlying Feeding Stimulation: Differential Contributions Of Src Family Tyrosine Kinases To Feeding Triggered Either By Nmda Injection Or By Food Deprivation, Arshad Khan, Herman H. Cheung, Elizabeth R. Gillard, Jennifer A. Palarca, Derek S. Welsbie, James W. Gurd, B. Glenn Stanley

Arshad M. Khan, Ph.D.

No abstract provided.

Rhodobacter Capsulatus Porphobilinogen Synthase, A High Activity Metal Ion Independent Hexamer, David W. Bollivar, Cheryl Clauson, Rachel Lighthall, Siiri Forbes, Bashkim Kokona, Robert Fairman, Lenka Kundrat, Eileen K. Jaffe

David Bollivar

Background: The enzyme porphobilinogen synthase (PBGS), which is central to the biosynthesis of heme, chlorophyll and cobalamins, has long been known to use a variety of metal ions and has recently been shown able to exist in two very different quaternary forms that are related to metal ion usage. This paper reports new information on the metal ion independence and quaternary structure of PBGS from the photosynthetic bacterium Rhodobacter capsulatus. Results: The gene for R. capsulatus PBGS was amplified from genomic DNA and sequencing revealed errors in the sequence database. R. capsulatus PBGS was heterologously expressed in E. coli and …

Evidence For And Characterization Of Ca2+ Binding To The Catalytic Region Of Arabidopsis Thaliana Phospholipase Dβ, Xuemin Wang

Xuemin (Sam) Wang

Evidence For Involvement Of An Electron Shuttle In Electricity Generation By Geothrix Fermentans, Daiel R. Bond, Derek Lovley

Derek Lovley

In experiments performed using graphite electrodes poised by a potentiostat (+200 mV versus Ag/AgCl) or in a microbial fuel cell (with oxygen as the electron acceptor), the Fe(III)-reducing organism Geothrix fermentans conserved energy to support growth by coupling the complete oxidation of acetate to reduction of a graphite electrode. Other organic compounds, such as lactate, malate, propionate, and succinate as well as components of peptone and yeast extract, were utilized for electricity production. However, electrical characteristics and the results of shuttling assays indicated that unlike previously described electrode-reducing microorganisms, G. fermentans produced a compound that promoted electrode reduction. This is …

High-Resolution Serum Proteomic Patterns For Ovarian Cancer Detection, Keith A. Baggerly, Sarah R. Edmonson, Jeffrey S. Morris, Kevin R. Coombes

Jeffrey S. Morris

No abstract provided.

Embryonic Expression Of Pre-Initiation Dna Replication Factors In Xenopus Laevis, Brian Walter, Jonathan Henry

Brian Walter

We examined the expression of various DNA replication factors, including: cdc45, the factors of the GINS heterotetramer (Sld5, Psf1, Psf2, Psf3), and PCNA, in Xenopus laevis during embryonic development via whole mount in situ hybridization. For the most part, these factors were expressed in similar patterns, with some subtle variations, throughout development within the anterior CNS, pharyngeal arches, and various placodes. More significant variations were also observed, including expression of only Psf1 and Psf2 in the pronephros and unique Psf2 expression in the somitic mesoderm. Overall, these results suggest that common regulatory mechanisms are involved in the transcriptional deployment of …

Is There An Antipredator Blood-Squirting Defense In The Bull Horned Lizard, Phrynosoma Taurus?, George Middendorf

George Middendorf

No abstract provided.

Jual Obat Bius Di Makasar 082313333253 Alamat Apotik Jual Obat Tidur / Bius Di Makasar, Toko Afeng Obat Kuat Bogor

toko afeng obat kuat bogor

Thermal And Sodium Dodecylsulfate Induced Transitions Of Streptavidin, Mark Waner, Irina Navrotskaya, Amanda Bain, Edward Oldham, David Mascotti

David P. Mascotti

The strong specific binding of streptavidin (SA) to biotin is utilized in numerous biotechnological applications. The SA tetramer is also known to exhibit significant stability, even in the presence of sodium dodecylsulfate (SDS). Despite its importance, relatively little is known about the nature of the thermal denaturation pathway for SA. This work uses a homogeneous SA preparation to expand on the data of previous literature reports, leading to the proposal of a model for temperature induced structural changes in SA. Temperature dependent data were obtained by SDS and native polyacrylamide gel electrophoresis (PAGE), differential scanning calorimetry (DSC), and fluorescence and …

Germination Of Silene Regia Seeds From Four Sites In Lawrence County, Illinois, Following Scarification Or Stratification, Nicolette L. Flocca, Janice M. Coons, Henry R. Owen, Brian J. Fischer, Bob E. Edgin

Henry R. Owen

Silene regia Sims is an endangered prairie forb in Illinois where small isolated colonies are scattered. In La·wrence County, two sites (Allison Prairie and Chauncey Marsh) have fewer plants (6-23) than two other sites (Cmmty Road and Cemetery) with 26-45 plants. Information on seed germination in these isolated colonies is needed. Our goal was to evaluate seed germination of S. regia from colonies in Lawrence County, illinois. S. regia fruits were collected from these four sites on August 9 and 19, 1999. Seeds were scarified by cutting the seed coat, or they were stratified at 2 C for 12 or …

Renesting Decisions And Annual Fecundity Of Female Dickcissels (Spiza Americana) In Illinois, Jeffrey W. Walk, Kevin Wentworth, Eric L. Kershner, Eric K. Bollinger, Richard E. Warner

Eric K. Bollinger

ABSTRACT.-Renesting decisions and annual fecundity are crucial for interpreting other demographic information, yet are infrequently reported. We used radiotelemetry to monitor female Dickcissels (Spiza americana) throughout the 1999 and 2000 breeding seasons in southeastern Illinois. Overall fecundity (regardless of whether females remained in the study area throughout the breeding season) was 0.61 ± 0.13 female fledglings per year. Of females that remained within the study area, 94% fledged young (1.25 ± 0.15 female fledglings per year). Most females (62%) that experienced nest failure emigrated from the study area (moved >10 km) in 2.8 ± 0.6 days; others (36%) initiated subsequent …

The Unpredictable Past Of Plasmodium Vivax Revealed In Its Genome, Stephen M. Rich

Stephen M. Rich

Until quite recently, very little information has been available about the genome content and structure of parasitic protozoa. This inadequacy has been rectified by the advent of high-throughput strategies that permit sequencing of whole genomes and enhanced computational capacities that render this information tractable. The current list of complete or near-complete genomes includes some of the greatest scourges of humans and their domesticated companions. Among these miscreants are several members of the genus Plasmodium, the agents of malaria. Scores of species of Plasmodium have been described and comprise pathogens of every major group of terrestrial vertebrates. At present, no less …

Soil Respiration And Nutrient Cycling In Wooded Communities Developing In Grassland, Rebecca L. Mcculley, S. R. Archer, T. W. Boutton, F. M. Hons, D. A. Zuberer

Rebecca L. McCulley

Grasslands and savannas worldwide are experiencing increases in woody plant abundance. In the subtropical Rio Grande Plains of southern Texas and northern Mexico, this change in physiognomy typically results in soil C and N accumulation. The extent to which this accumulation is the result of increased C and N inputs vs. decreased losses is not known. To address this issue, we compared soil C and N pools, soil respiration, soil microbial biomass, and potential C and N mineralization and nitrification rates in remnant grassland communities and adjacent woody plant communities known to have developed on grassland within the past 100 …

The Multidisciplinary Influence Of Common Sustainability Indices, Audrey L. Mayer, Hale W. Thurston, Christopher W. Pawlowski

Audrey Mayer

The Functions Of Animal Micrornas., Victor Ambros

Victor R. Ambros

MicroRNAs (miRNAs) are small RNAs that regulate the expression of complementary messenger RNAs. Hundreds of miRNA genes have been found in diverse animals, and many of these are phylogenetically conserved. With miRNA roles identified in developmental timing, cell death, cell proliferation, haematopoiesis and patterning of the nervous system, evidence is mounting that animal miRNAs are more numerous, and their regulatory impact more pervasive, than was previously suspected.

'Mass Delusion' Or 'True Myth'? Pbs Considers The Question Of God, Stephen Asma

Stephen T Asma

The Question of God is a new 4-hour miniseries from PBS. It is based on a long-running course taught by Harvard University psychiatry professor Armand Nicholi that compares the biographies and theories of Sigmund Freud, skeptic, and C. S. Lewis, believer. On balance, the miniseries succeeds as an introduction to complex issues.

Overweight In Urban, Low-Income, African American And Hispanic Children Attending Los Angeles Elementary Schools: Research Stimulating Action, Wendelin M. Slusser, William G. Cumberland, Ben L. Browdy, Donna Winham, Charlotte G. Neumann

Donna Winham

Objective: This study was undertaken to establish the prevalence and severity of nutritional problems among low-income children of elementary school age in the Los Angeles Unified School District (LAUSD) in order to collect baseline data to inform policy-makers. Design and methods: A cross-sectional survey of children in 14 elementary schools was conducted from January to June, 1998. Nine hundred and nineteen children were measured and interviewed. The planning, design and data analysis were carried out in collaboration with key LAUSD policy-makers. Results: More than 35% of the sample was classified as being at risk for overweight or overweight according to …

Ecological And Agricultural Applications Of Synchrotron Ir Microscopy, Ted K. Raab, John P. Vogel

Ted K. Raab

The diffraction-limited spot size of synchrotron-based IR microscopes provides cell-specific, spectrochemical imaging of cleared leaf, stem and root tissues of the model genetic organism Arabidopsis thaliana, and mutant plants created either by T-DNA insertional inactivation or chemical mutagenesis. Spectra in the wavelength region from 6 to 12 microns provide chemical and physical information on the cell wall polysaccharides of mutants lacking particular biosynthetic enzymes (‘‘Cellulose synthase-like’’ genes). In parallel experiments, synchrotron IR microscopy delineates the role of Arabidopsis cell wall enzymes as susceptibility factors to the fungus Erysiphe cichoracearum, a causative agent of powdery mildew disease. Three genes, pmr4, pmr5, …

Single-Cell Microbiology: Tools, Technologies, And Applications, Byron F. Brehm-Stecher, Eric A. Johnson

Byron F. Brehm-Stecher

The field of microbiology has traditionally been concerned with and focused on studies at the population level. Information on how cells respond to their environment, interact with each other, or undergo complex processes such as cellular differentiation or gene expression has been obtained mostly by inference from population-level data. New appreciation for the existence and importance of cellular heterogeneity, coupled with recent advances in technology, has driven the development of new tools and techniques for the study of individual microbial cells. As a result, scientists have been able to characterize microorganisms and their activities at unprecedented levels of detail.