Life Sciences Commons^™

Electricity Production By Geobacter Sulfurreducens Attached To Electrodes, Daniel R. Bond, Derek Lovley

Derek Lovley

Previous studies have suggested that members of the Geobacteraceae can use electrodes as electron acceptors for anaerobic respiration. In order to better understand this electron transfer process for energy production, Geobacter sulfurreducens was inoculated into chambers in which a graphite electrode served as the sole electron acceptor and acetate or hydrogen was the electron donor. The electron-accepting electrodes were maintained at oxidizing potentials by connecting them to similar electrodes in oxygenated medium (fuel cells) or to potentiostats that poised electrodes at +0.2 V versus an Ag/AgCl reference electrode (poised potential). When a small inoculum of G. sulfurreducens was introduced into …

Whole-Genome Analysis Of Dorsal-Ventral Patterning In The Drosophila Embryo, Angelike Stathopoulos, Madeleine Van Drenth, Albert Erives, Michele Markstein, Michael Levine

Michele Markstein

The maternal Dorsal regulatory gradient initiates the differentiation of several tissues in the early Drosophila embryo. Whole-genome microarray assays identified as many as 40 new Dorsal target genes, which encode a broad spectrum of cell signaling proteins and transcription factors. Evidence is presented that a tissue-specific form of the NF-Y transcription complex is essential for the activation of gene expression in the mesoderm. Tissue-specific enhancers were identified for new Dorsal target genes, and bioinformatics methods identified conserved cis-regulatory elements for coordinately regulated genes that respond to similar thresholds of the Dorsal gradient. The new Dorsal target genes and enhancers represent …

Plant Rac-Like Gtpases Are Activated By Auxin And Mediate Auxin-Responsive Gene Expression, L. Z. Tao, Alice Cheung, H. M. Wu

Alice Cheung

The auxin indole-3-acetic acid is a key plant hormone essential for a broad range of growth and developmental processes. Here, we show that auxin activates Rac-like GTPases (referred to as Rac/Rop GTPases), and they in turn stimulate auxin-responsive gene expression. In particular, we show that overexpressing a wild-type tobacco Rac/Rop GTPase, NtRac1, and its constitutively active mutant form activates auxin-responsive gene expression. On the other hand, overexpressing dominant-negative NtRac1 and Rac-negative regulators, or reducing the endogenous NtRac1 level, suppresses auxin-induced gene expression. Furthermore, overexpression of NtRac1 activity or suppression of its expression in transgenic seedlings induces phenotypes that are similar …

Decoding Cis-Regulatory Dnas In The Drosophila Genome, Michele Markstein, Michael Levine

Michele Markstein

Cis-regulatory DNAs control the timing and sites of gene expression during metazoan development. Changes in gene expression are responsible for the morphological diversification of metazoan body plans. However, traditional methods for the identification and characterization of cis-regulatory DNAs are tedious. During the past year, computational methods have been used to identify novel cis-DNAs within the entire Drosophila genome. These methods change the way that cis-DNAs will be analyzed in future studies and offer the promise of unraveling complex gene networks.

The Regulation Of Actin Organization By Actin-Depolymerizing Factor In Elongating Pollen Tubes, C. Y. Chen, E. I. Wong, L. Vidali, A. Estavillo, P. K. Hepler, H. M. Wu, Alice Cheung

Alice Cheung

Pollen tube elongation is a polarized cell growth process that transports the male gametes from the stigma to the ovary for fertilization inside the ovules. Actomyosin-driven intracellular trafficking and active actin remodeling in the apical and subapical regions of pollen tubes are both important aspects of this rapid tip growth process. Actin-depolymerizing factor (ADF) and cofilin are actin binding proteins that enhance the depolymerization of microfilaments at their minus, or slow-growing, ends. A pollen-specific ADF from tobacco, NtADF1, was used to dissect the role of ADF in pollen tube growth. Overexpression of NtADF1 resulted in the reduction of fine, axially …

Mechanisms For Accessing Insoluble Fe(Iii) Oxide During Dissimilatory Fe(Iii) Reduction By Geothrix Fermentans, Kelly P. Nevin, Derek Lovley

Kelly Nevin

Mechanisms for Fe(III) oxide reduction were investigated in Geothrix fermentans, a dissimilatory Fe(III)-reducing microorganism found within the Fe(III) reduction zone of subsurface environments. Culture filtrates of G. fermentans stimulated the reduction of poorly crystalline Fe(III) oxide by washed cell suspensions, suggesting that G. fermentans released one or more extracellular compounds that promoted Fe(III) oxide reduction. In order to determine if G. fermentans released electron-shuttling compounds, poorly crystalline Fe(III) oxide was incorporated into microporous alginate beads, which prevented contact between G. fermentans and the Fe(III) oxide. G. fermentans reduced the Fe(III) within the beads, suggesting that one of the compounds that …

Knockout And Transgenic Mice Of Trp53: What Have We Learned About P53 In Breast Cancer?, Anneke C. Blackburn, D. Joseph Jerry

D. Joseph Jerry

The human p53 tumor suppressor gene TP53 is mutated at a high frequency in sporadic breast cancer, and Li-Fraumeni syndrome patients who carry germline mutations in one TP53 allele have a high incidence of breast cancer. In the 10 years since the first knockout of the mouse p53 tumor suppressor gene (designated Trp53) was published, much has been learned about the contribution of p53 to biology and tumor suppression in the breast through the use of p53 transgenic and knockout mice. The original mice deficient in p53 showed no mammary gland phenotype. However, studies using BALB/c-Trp53-deficient mice have demonstrated a …

Hormonal Control Of P53 And Chemoprevention, D. Joseph Jerry, Lisa M. Minter, Klaus A. Becker, Anneke C. Blackburn

D. Joseph Jerry

Improvements in the detection and treatment of breast cancer have dramatically altered its clinical course and outcome. However, prevention of breast cancer remains an elusive goal. Parity, age of menarche, and age at menopause are major risk factors drawing attention to the important role of the endocrine system in determining the risk of breast cancer, while heritable breast cancer susceptibility syndromes have implicated tumor suppressor genes as important targets. Recent work demonstrating hormonal modulation of the p53 tumor suppressor pathway draws together these established determinants of risk to provide a model of developmental susceptibility to breast cancer. In this model, …

Using Small Group Assignments In Teaching Research Ethics, Kenneth D. Pimple

Ethics in Science and Engineering National Clearinghouse

No abstract provided.

Using Short Writing Assignments In Teaching Research Ethics, Kenneth D. Pimple

Ethics in Science and Engineering National Clearinghouse

Regularly asking students to write down their thoughts and reactions to class readings and discussions is an effective method of teaching and assessing student learning. Furthermore, as composition teachers will attest, frequent writing assignments, regardless of content, dramatically improve writing skills. Asking students to think “on paper” about topics encountered in the classroom encourages them to think about those topics in greater depth, relate them to their own lives, and thus connect the classroom to the world outside. I will describe four kinds of useful short writing assignments – freewriting, the non-quiz, the one-minute paper, and logbooks.

Enrichment Of Members Of The Family Geobacteraceae Associated With Stimulation Of Dissimilatory Metal Reduction In Uranium-Contaminated Aquifer Sediments, Dawn E. Holmes, Kevin T. Finneran, Regina A. O'Neil, Derek Lovley

Derek Lovley

Stimulating microbial reduction of soluble U(VI) to insoluble U(IV) shows promise as a strategy for immobilizing uranium in uranium-contaminated subsurface environments. In order to learn more about which microorganisms might be involved in U(VI) reduction in situ, the changes in the microbial community when U(VI) reduction was stimulated with the addition of acetate were monitored in sediments from three different uranium-contaminated sites in the floodplain of the San Juan River in Shiprock, N.Mex. In all three sediments U(VI) reduction was accompanied by concurrent Fe(III) reduction and a dramatic enrichment of microorganisms in the family Geobacteraceae, which are known U(VI)- and …

Mechanisms For Accessing Insoluble Fe(Iii) Oxide During Dissimilatory Fe(Iii) Reduction By Geothrix Fermentans, Kelly P. Nevin, Derek Lovley

Derek Lovley

Mechanisms for Fe(III) oxide reduction were investigated in Geothrix fermentans, a dissimilatory Fe(III)-reducing microorganism found within the Fe(III) reduction zone of subsurface environments. Culture filtrates of G. fermentans stimulated the reduction of poorly crystalline Fe(III) oxide by washed cell suspensions, suggesting that G. fermentans released one or more extracellular compounds that promoted Fe(III) oxide reduction. In order to determine if G. fermentans released electron-shuttling compounds, poorly crystalline Fe(III) oxide was incorporated into microporous alginate beads, which prevented contact between G. fermentans and the Fe(III) oxide. G. fermentans reduced the Fe(III) within the beads, suggesting that one of the compounds that …

Genome-Wide Analysis Of Clustered Dorsal Binding Sites Identifies Putative Target Genes In The Drosophila Embryo, Michele Markstein, Peter Markstein, Vicky Markstein, Michael Levine

Michele Markstein

Metazoan genomes contain vast tracts of cis-regulatory DNA that have been identified typically through tedious functional assays. As a result, it has not been possible to uncover a cis-regulatory code that links primary DNA sequences to gene expression patterns. In an initial effort to determine whether coordinately regulated genes share a common “grammar,” we have examined the distribution of Dorsal recognition sequences in the Drosophila genome. Dorsal is one of the best-characterized sequence-specific transcription factors in Drosophila. The homeobox gene zerknullt (zen) is repressed directly by Dorsal, and this repression is mediated by a 600-bp silencer, the ventral repression element …

Use Of Fe(Iii) As An Electron Acceptor To Recover Previously Uncultured Hyperthermophilesl Isolation And Characterization Of Geothermobacterium Ferrireducens Gen.Nov., Sp. Nov., Kazem Kashefi, Dawn E. Holmes, Anna-Louise Reysenbach, Derek Lovley

Derek Lovley

It has recently been recognized that the ability to use Fe(III) as a terminal electron acceptor is a highly conserved characteristic in hyperthermophilic microorganisms. This suggests that it may be possible to recover as-yet-uncultured hyperthermophiles in pure culture if Fe(III) is used as an electron acceptor. As part of a study of the microbial diversity of the Obsidian Pool area in Yellowstone National Park, Wyo., hot sediment samples were used as the inoculum for enrichment cultures in media containing hydrogen as the sole electron donor and poorly crystalline Fe(III) oxide as the electron acceptor. A pure culture was recovered on …

Effects Of Gibberellin Synthesis Inhibition On Feeding Injury By Potato Leafhopper On Apple, Kathleen Leahy, Duane Greene, Wesley Autio

Wesley Autio

No abstract provided.

Clostridium Phytofermentans Sp. Nov., A Cellulolytic Mesophile From Forest Soil., Susan Leschine, T. A. Warnick

Susan Leschine

An obligately anaerobic, mesophilic, cellulolytic bacterium, strain ISDgT, was isolated from forest soil. Cells of this isolate stained Gram-negative, despite possessing a Gram-positive cell-wall ultrastructure, and were motile, straight rods that formed spherical terminal spores that swelled the sporangium. Cellulose, pectin, polygalacturonic acid, starch, xylan, arabinose, cellobiose, fructose, galactose, gentiobiose, glucose, lactose, maltose, mannose, ribose and xylose supported growth. The major end products of fermentation were ethanol, acetate, CO2 and H2; formate and lactate were minor products. The optimum temperature for growth was 35-37 degrees C. Phylogenetic analyses based on 16S rRNA sequence comparisons showed that strain ISDgT was related …

Cellulose Synthase-Like (Csl) Genes Of Rice, Samuel P. Hazen, J. S. Scott-Craig, J. D. Walton

Samuel P Hazen

No abstract provided.

Mutant Alleles Of Arabidopsis Radially Swollen 4 And Rsw7 Reduce Growth Anisotropy Without Altering The Transverse Orientation Of Cortical Microtubules Or Cellulose Microfibrils, Tobias Baskin, A.M.D. Wiedemeier, J.E. Judy-March, C.H. Hocart, G.O. Wasteneys, R.E. Williamson

Tobias Baskin

The anisotropic growth of plant cells depends on cell walls having anisotropic mechanical properties, which are hypothesized to arise from aligned cellulose microfibrils. To test this hypothesis and to identify genes involved in controlling plant shape, we isolated mutants in Arabidopsis thaliana in which the degree of anisotropic expansion of the root is reduced. We report here the characterization of mutants at two new loci, RADIALLY SWOLLEN 4 (RSW4) and RSW7. The radial swelling phenotype is temperature sensitive, being moderate (rsw7) or negligible (rsw4) at the permissive temperature, 19°C, and pronounced at the restrictive temperature, 30°C. After transfer to 30°C, …

Epithelial Cell Cycling Predicts P53 - Repsoniveness To Γ-Irradiation During Post-Natal Mammary Gland Development, Lisa Minter, E.S. Dickinson, S.P. Naber, D.J. Jerry

Lisa Minter

The tumor suppressor gene, TP53, plays a major role in surveillance and repair of radiation-induced DNA damage. In multiple cell types, including mammary epithelial cells, abrogation of p53 (encoded by Trp53) function is associated with increased tumorigenesis. We examined γ-irradiated BALB/c-Trp53+/+ and -Trp53–/– female mice at five stages of post-natal mammary gland development to determine whether radiation-induced p53 activity is developmentally regulated. Our results show that p53-mediated responses are attenuated in glands from irradiated virgin and lactating mice, as measured by induction of p21/WAF1 (encoded by Cdkn1a) and apoptosis, while irradiated early- and mid-pregnancy glands exhibit robust p53 activity. There …

Development Of A Model For Predicting Flyspeck Risks In Blocks Of Apple Trees, Arthur Tuttle, Christopher Bergweiler, James Hall, Lisa Reisner, Steven Christle, Wesley Autio, Daniel Cooley

Wesley Autio

No abstract provided.

Performance Of The V Series Apple Rootstocks During Six Growing Seasons, Wesley Autio, James Krupa

Wesley Autio

No abstract provided.

Trp-Dependent Auxin Biosynthesis In Arabidopsis: Involvement Of Cytochrome P450s Cyp79b2 And Cyp79b3, Yunde Zhao, Anna K. Hull, Neeru R. Gupta, Kendrick A. Goss, José Alonso, Joseph R. Ecker, Jennifer Normanly, Joanne Chory, John L. Celenza

Jennifer Normanly

The plant hormone auxin regulates many aspects of plant growth and development. Although several auxin biosynthetic pathways have been proposed, none of these pathways has been precisely defined at the molecular level. Here we provide in planta evidence that the two Arabidopsis cytochrome P450s, CYP79B2 and CYP79B3, which convert tryptophan (Trp) to indole-3-acetaldoxime (IAOx) in vitro, are critical enzymes in auxin biosynthesis in vivo. IAOx is thus implicated as an important intermediate in auxin biosynthesis. Plants overexpressing CYP79B2 contain elevated levels of free auxin and display auxin overproduction phenotypes. Conversely, cyp79B2 cyp79B3 double mutants have reduced levels of IAA and …

Analysis Of The Genetic Potential And Gene Expression Of Microbial Communities Involved In The In Situ Bioremediation Of Uranium And Harvesting Electrical Energy From Organic Matter, Derek Lovley

Derek Lovley

The goal of this genomes-to-life project is to develop models that can describe the functioning of the microbial communities involved in the in situ bioremediation of uranium-contaminated groundwater and harvesting electricity from waste organic matter. Previous studies have demonstrated that the microbial communities involved in uranium bioremediation and energy harvesting are both dominated by microorganisms in the family Geobacteraceae and that these Geobacteraceae are responsible for the uranium bioremediation and electron transfer to electrodes. The research plan is diagrammed below. Examples of how both pure culture and environmental genomic studies have dramatically changed the concepts of how Geobacteraceae-dominated subsurface communities …

Hormonal Control Of P53 And Chemoprevention, Lisa Minter, D.J. Jerry, K.A. Becker, A.C. Blackburn

Lisa Minter

Improvements in the detection and treatment of breast cancer have dramatically altered its clinical course and outcome. However, prevention of breast cancer remains an elusive goal. Parity, age of menarche, and age at menopause are major risk factors drawing attention to the important role of the endocrine system in determining the risk of breast cancer, while heritable breast cancer susceptibility syndromes have implicated tumor suppressor genes as important targets. Recent work demonstrating hormonal modulation of the p53 tumor suppressor pathway draws together these established determinants of risk to provide a model of developmental susceptibility to breast cancer. In this model, …

Immunological Characterization Of A T Cell Stimulatory Ligand On Autologous Monocytes, T. Sathiyaseelan, B. Naimen, S. Welte, N. Machugh, S.J. Black, Cynthia Baldwin

Cynthia Baldwin

Bovine gammadelta T cells are stimulated to proliferate by autologous monocytes. This is referred to as the autologous mixed leucocyte reaction (AMLR). It has been shown previously that the stimulatory component is constitutively expressed on the monocyte plasma membrane and is a protein or has a protein moiety. Here we showed that gammadelta T-cell responses to the monocytes requires interaction with the T-cell receptor because Fab1 fragments of a monoclonal antibody (mAb) that reacts with the delta chain of the T-cell receptor blocked proliferation in the AMLR. Monocyte molecules involved in stimulation were also characterized further by biochemical and immunological …

Squeaking With A Sliding Joint: Mechanics And Motor Control Of Sound Production In Palinurid Lobsters, Sheila Patek

Sheila Patek

The origin of arthropod sound-producing morphology typically involves modification of two translating body surfaces, such as the legs and thorax. In an unusual structural rearrangement, I show that one lineage of palinurid lobsters lost an antennal joint articulation, which transformed this joint from moving with one degree of freedom into a sliding joint with multiple degrees of freedom. With this sliding joint, `stick-and-slip' sounds are produced by rubbing the base of each antenna against the antennular plate. To understand the musculo-skeletal changes that occurred during the origin and evolutionary variation of this sound-producing mechanism, I examined joint morphology and antennal …

Host Effects On Herbivory And Pollination In A Hemiparasitic Plant, Lynn Adler

Lynn Adler

The indirect effects of hosts on interactions between parasites and other species are not well understood, and it may be difficult to predict the outcome of host species effects on parasite performance due to the complexity of potential direct and indirect effects. For example, parasitic plants obtain defensive compounds as well as nutrients from their hosts, and thus many attributes of parasitic plants are dependent on the quality of their host species. Here I measure the effect of a lupine host species (Lupinus argenteus) compared to other host species on herbivory, pollination, and female plant fitness in the hemiparasite Indian …

Centrosome Reorientation In Wound-Edge Cells Is Cell Type Specific, Patricia Wadsworth, A. C. Yvon, J. W. Walker, B. A. Danowski, C. Fagerstrom, A. Khojakov

Patricia Wadsworth

The reorientation of the microtubule organizing center during cell migration into a wound in the monolayer was directly observed in living wound-edge cells expressing γ-tubulin tagged with green fluorescent protein. Our results demonstrate that in CHO cells, the centrosome reorients to a position in front of the nucleus, toward the wound edge, whereas in PtK cells, the centrosome lags behind the nucleus during migration into the wound. In CHO cells, the average rate of centrosome motion was faster than that of the nucleus; the converse was true in PtK cells. In both cell lines, centrosome motion was stochastic, with periods …

Assessing Student Learning In The Responsible Conduct Of Research, Kenneth D. Pimple

Ethics in Science and Engineering National Clearinghouse

Introduction

As with all effective teaching, a key element in any unit designed to teach research ethics is assessment of student learning, whether the “unit” is a whole course, a brown bag lunch seminar, or a few sessions or segments of sections within a course. How can we know what our students learned, and whether they learned what we intended them to learn? How can we tell whether our instructional goals were met?

I am reminded of the Saturday Night Live skit in which a reporter asks President Carter, “Why are you building the B-1 Bomber?” To which Carter replies, …