Life Sciences Commons^™

The Relationship Between Frq-Protein Stability And Temperature Compensation In The Neurospora Circadian Clock, Peter Ruoff, Jennifer J. Loros, Jay C. Dunlap

Dartmouth Scholarship

Temperature compensation is an important property of all biological clocks. In Neurospora crassa, negative-feedback regulation on the frequency (frq) gene's transcription by the FRQ protein plays a central role in the organism's circadian pacemaker. Earlier model calculations predicted that the stability of FRQ should determine the period length of Neurospora's circadian rhythm as well as the rhythm's temperature compensation. Here, we report experimental FRQ protein stabilities in frq mutants at 20 degrees C and 25 degrees C, and estimates of overall activation energies for mutant FRQ protein degradation. The results are consistent with earlier model predictions, i.e., temperature compensation of …

The Role Of An Explicit Causal Framework In Affected Sib Pair Designs With Covariates , Constantine E. Frangakis, Fan Li, Betty Q. Doan

Johns Hopkins University, Dept. of Biostatistics Working Papers

The affected sib/relative pair (ASP/ARP) design is often used with covariates to find genes that can cause a disease in pathways other than through those covariates. However, such "covariates" can themselves have genetic determinants, and the validity of existing methods has so far only been argued under implicit assumptions. We propose an explicit causal formulation of the problem using potential outcomes and principal stratification. The general role of this formulation is to identify and separate the meaning of the different assumptions that can provide valid causal inference in linkage analysis. This separation helps to (a) develop better methods under explicit …

Genetic And Molecular Analysis Of Phytochromes From The Filamentous Fungus Neurospora Crassa, Allan C. Froehlich, Bosl Noh, Richard D. Vierstra, Jennifer Loros, Jay C. Dunlap

Dartmouth Scholarship

Phytochromes (Phys) comprise a superfamily of red-/far-red-light-sensing proteins. Whereas higher-plant Phys that control numerous growth and developmental processes have been well described, the biochemical characteristics and functions of the microbial forms are largely unknown. Here, we describe analyses of the expression, regulation, and activities of two Phys in the filamentous fungus Neurospora crassa. In addition to containing the signature N-terminal domain predicted to covalently associate with a bilin chromophore, PHY-1 and PHY-2 contain C-terminal histidine kinase and response regulator motifs, implying that they function as hybrid two-component sensor kinases activated by light. A bacterially expressed N-terminal fragment of PHY-2 covalently …

Emerging Research Techniques & New Instrumentation For Plant Biology, Bruce Bugbee

Techniques and Instruments

We have not achieved an efficient food production system in US Agriculture by manipulating only the environment.

Genetic engineering techniques now allow us to quickly develop new crop cultivars.

Silencing Of Retrotransposons In Dictyostelium By Dna Methylation And Rnai., Markus Kuhlmann, Branimira E. Borisova, Markus Kaller, Pontus Larsson, Dirk Stach, Jianbo Na, Ludwig Eichinger, Frank Lyko, Victor R. Ambros, Fredrik Soderbom, Christian Hammann, Wolfgang Nellen

Victor R. Ambros

We have identified a DNA methyltransferase of the Dnmt2 family in Dictyostelium that was denominated DnmA. Expression of the dnmA gene is downregulated during the developmental cycle. Overall DNA methylation in Dictyostelium is approximately 0.2% of the cytosine residues, which indicates its restriction to a limited set of genomic loci. Bisulfite sequencing of specific sites revealed that DnmA is responsible for methylation of mostly asymmetric C-residues in the retrotransposons DIRS-1 and Skipper. Disruption of the gene resulted in a loss of methylation and in increased transcription and mobilization of Skipper. Skipper transcription was also upregulated in strains that had genes …

When Should Judges Admit Or Compel Genetic Tests?, Diane E. Hoffmann, Karen H. Rothenberg

Faculty Scholarship

No abstract provided.

Day 2: Thursday, 18 August 2005: Upper Colorado River Endangered Fish Recovery Program, Bob Muth, Tom Pitts, Dan Luecke

Endangered Species Act Congressional Field Tour (August 17-19)

58 pages (includes illustrations and maps).

Contains references.

Sara Positively Controls Bap-Dependent Biofilm Formation In Staphylococcus Aureus, María P. Trotonda, Adhar C. Manna, Ambrose L. Cheung, Iñigo Lasa, José R. Penadés

Dartmouth Scholarship

The biofilm-associated protein Bap is a staphylococcal surface protein involved in biofilm formation. We investigated the influence of the global regulatory locus sarA on bap expression and Bap-dependent biofilm formation in three unrelated Staphylococcus aureus strains. The results showed that Bap-dependent biofilm formation was diminished in the sarA mutants by an agr-independent mechanism. Complementation studies using a sarA clone confirmed that the defect in biofilm formation was due to the sarA mutation. As expected, the diminished capacity to form biofilms in the sarA mutants correlated with the decreased presence of Bap in the bacterial surface. Using transcriptional fusion and …

Sheep Updates 2005 - Part 5, Geoff Duddy, Brent Mcloud, John Sullivan, T. J. Mahar, A. Balasingam, J. H. Stanton, K. M. S. Curtis, P. R. Lamb, Eliza Dowling, Ned Crossley, Surrender Mann, Lucy Anderton, Matthew Kelly, Andrew Swan, Ian Mcfarland, Di Evans, K. Bell, D. Sackett, Robin Jacob

Sheep Updates

This session covers eleven papers from different authors; MARKET INFORMATION 1. Crystal Spring - Crystal clear and consistant, Geoff Duddy, Livestock Officer (Sheep & Wool) Yanco, NSW, Brent McLoud, (Product Development Officer) Cowra, NSW, John Sullivan, J.J Dresser and Co (Agent), Woodstock, NSW 2. An overview of Recent Developments in Dark and Medullated Fibre Testing, T.J. Mahar, A. Balasingam, AWTA Ltd 3. Opportunities and Implications for Wool Producers of the TEAM3 Prediction Equations, J.H. Stanton12 K.M.S. Curtis1 , 1Department of Agriculture Western Australia, 2 Curtin University, WA 4. Premiums and Discounts for Fibre Properties in Superfine Wool, Now and in …

A Critical Role For Kalirin In Ngf Signaling Through Trka, Kausik Chakrabarti, Rong Lin, Noraisha I. Schiller, Yanping Wang, David Koubi, Ying-Xin Fan, Brian B. Rudkin, Gibbes R. Johnson, Martin R. Schiller

Life Sciences Faculty Research

Kalirin is a multidomain guanine nucleotide exchange factor (GEF) that activates Rho proteins, inducing cytoskeletal rearrangement in neurons. Although much is known about the effects of Kalirin on Rho GTPases and neuronal morphology, little is known about the association of Kalirin with the receptor/signaling systems that affect neuronal morphology. Our experiments demonstrate that Kalirin binds to and colocalizes with the TrkA neurotrophin receptor in neurons. In PC12 cells, inhibition of Kalirin expression using antisense RNA decreased nerve growth factor (NGF)-induced TrkA autophosphorylation and process extension. Kalirin overexpression potentiated neurotrophin-stimulated TrkA autophosphorylation and neurite outgrowth in PC12 cells at a low …

New Statistical Paradigms Leading To Web-Based Tools For Clinical/Translational Science, Knut M. Wittkowski

COBRA Preprint Series

As the field of functional genetics and genomics is beginning to mature, we become confronted with new challenges. The constant drop in price for sequencing and gene expression profiling as well as the increasing number of genetic and genomic variables that can be measured makes it feasible to address more complex questions. The success with rare diseases caused by single loci or genes has provided us with a proof-of-concept that new therapies can be developed based on functional genomics and genetics.

Common diseases, however, typically involve genetic epistasis, genomic pathways, and proteomic pattern. Moreover, to better understand the underlying biologi-cal …

Integrated Recombinant Protein Expression And Purification Platform Based On Ralstonia Eutropha, Gavin C. Barnard, Jesse D. Mccool, David W. Wood, Tillman U. Gerngross

Dartmouth Scholarship

Protein purification of recombinant proteins constitutes a significant cost of biomanufacturing and various efforts have been directed at developing more efficient purification methods. We describe a protein purification scheme wherein Ralstonia eutropha is used to produce its own “affinity matrix,” thereby eliminating the need for external chromatographic purification steps. This approach is based on the specific interaction of phasin proteins with granules of the intracellular polymer poly

Composite Genome Map And Recombination Parameters Derived From Three Archetypal Lineages Of Toxoplasma Gondii, Asis Khan, Sonya Taylor, Chunlei Su, Aaron J. Mackey, Jon Boyle, Robert Cole, Darius Glover, Keliang Tang, Ian T. Paulsen, Matt Berriman, John C. Boothroyd, Elmer K. Pfefferkorn, J P. Dubey, James W. Ajioka, David S. Roos, John C. Wootton, David Sibley

Dartmouth Scholarship

Toxoplasma gondii is a highly successful protozoan parasite in the phylum Apicomplexa, which contains numerous animal and human pathogens. T.gondii is amenable to cellular, biochemical, molecular and genetic studies, making it a model for the biology of this important group of parasites. To facilitate forward genetic analysis, we have developed a high-resolution genetic linkage map for T.gondii . The genetic map was used to assemble the scaffolds from a 10X shotgun whole genome sequence, thus defining 14 chromosomes with markers spaced at ∼300 kb intervals across the genome. Fourteen chromosomes were identified comprising a total genetic size of ∼592 cM …

Identification Of Key Genes Required For Abiotic Stress Response In Arabidopsis Thaliana, Saori Endo

Undergraduate Honors Capstone Projects

To identify key genes that are required for stress response, a reverse genetics approach was taken to manipulate expression of candidate genes in plants. In this project, two potential regulatory genes which were originally identified as stress-responsive genes from a microarray experiment in Arabidopsis were examined for their roles in stress tolerance. Over-expression of gene A, which was up-regulated under stress conditions based on the array data, caused earlier flowering and improved plant growth under salinity and dehydration stress conditions at the seedling stage. Over-expression of gene B, which was down-regulated under stress conditions based on the array data, resulted …

Sara Is An Essential Positive Regulator Of Staphylococcus Epidermidis Biofilm Development, Maria A. Tormo, Miguel Marti, Jaione Valle, Adhar C. Manna

Dartmouth Scholarship

Staphylococcus epidermidis biofilm formation is associated with the production of the polysaccharide intercellular adhesin (PIA)--poly-N-acetylglucosamine polysaccharide (PNAG) by the products of the icaADBC operon. Recent evidence indicates that SarA, a central regulatory element that controls the production of Staphylococcus aureus virulence factors, is essential for the synthesis of PIA/PNAG and the ensuing biofilm development in this species. Based on the presence of a sarA homolog, we hypothesized that SarA could also be involved in the regulation of the biofilm formation process in S. epidermidis. To investigate this, we constructed nonpolar sarA deletions in two genetically unrelated S. epidermidis clinical strains, …

Searching For Differentially Expressed Gene Combinations, Marcel Dettling, Edward Gabrielson, Giovanni Parmigiani

Johns Hopkins University, Dept. of Biostatistics Working Papers

Background: Comparison of mRNA expression levels across biological samples is a widely used approach in genomics. Available data-analytic tools for deriving comprehensive lists of differentially expressed genes rely on data summaries formed using each gene in isolation from others. These approaches ignore biological relationships among genes and may miss important biological insight provided by genomics data.

Methods: We propose a fast, easily interpretable and scalable approach for identifying pairs of genes that are differentially expressed across phenotypes or experimental conditions. These are defined as pairs for which there is detectable phenotype discrimination using the joint distribution, but not from either …

From The Cover: Assignment Of An Essential Role For The Neurospora Frequency Gene In Circadian Entrainment To Temperature Cycles, Antonio M. Pregueiro, Nathan Price-Lloyd, Deborah Bell-Pedersen, Christian Heintzen, Jennifer J. Loros, Jay C. Dunlap

Dartmouth Scholarship

Circadian systems include slave oscillators and central pacemakers, and the cores of eukaryotic circadian clocks described to date are composed of transcription and translation feedback loops (TTFLs). In the model system Neurospora, normal circadian rhythmicity requires a TTFL in which a White Collar complex (WCC) activates expression of the frequency (frq) gene, and the FRQ protein feeds back to attenuate that activation. To further test the centrality of this TTFL to the circadian mechanism in Neurospora, we used low-amplitude temperature cycles to compare WT and frq-null strains under conditions in which a banding rhythm was elicited. WT cultures were entrained …

A Rab Requirement Is Not Bypassed In Sly1-20 Suppression, Nicole Ballew, Yiting Liu, Charles Barlowe

Dartmouth Scholarship

The Rab GTPase Ypt1p and the large homodimer Uso1p are both required for tethering endoplasmic reticulum-derived vesicles to early Golgi compartments in yeast. Loss-of-function ypt1 and uso1 mutations are suppressed by SLY1-20, a dominant allele that encodes the Sed5p-associated protein, Sly1p. Here, we investigate the mechanism of SLY1-20 suppression. In wild-type strains, Ypt1p can be coimmunoprecipitated with Uso1p; however, in a ypt1Δ/SLY1-20 strain, which lacks this complex, membrane binding of Uso1p was reduced. In spite of Ypt1p depletion, Uso1p-dependent vesicle tethering was not bypassed under the ypt1Δ/SLY1-20 condition. Moreover, tethering and fusion assays with ypt1 …

A Three-Component Regulatory System Regulates Biofilm Maturation And Type Iii Secretion In Pseudomonas Aeruginosa, Sherry L. Kuchma, John P. Connolly, George A. O'Toole

Dartmouth Scholarship

Biofilms are structured communities found associated with a wide range of surfaces. Here we report the identification of a three-component regulatory system required for biofilm maturation by Pseudomonas aeruginosa strain PA14. A transposon mutation that altered biofilm formation in a 96-well dish assay originally defined this locus, which is comprised of genes for a putative sensor histidine kinase and two response regulators and has been designated sadARS. Nonpolar mutations in any of the sadARS genes result in biofilms with an altered mature structure but do not confer defects in growth or early biofilm formation, swimming, or twitching motility. After …

Yos1p Is A Novel Subunit Of The Yip1p–Yif1p Complex And Is Required For Transport Between The Endoplasmic Reticulum And The Golgi Complex, Matthew Heidtman, Catherine Z. Chen, Ruth N. Collins, Charles Barlowe

Dartmouth Scholarship

Yeast Yip1p is a member of a conserved family of transmembrane proteins that interact with Rab GTPases. Previous studies also have indicated a role for Yip1p in the biogenesis of endoplasmic reticulum (ER)-derived COPII transport vesicles. In this report, we describe the identification and characterization of the uncharacterized open reading frame YER074W-A as a novel multicopy suppressor of the thermosensitive yip1-4 strain. We have termed this gene Yip One Suppressor 1 (YOS1). Yos1p is essential for growth and for function of the secretory pathway; depletion or inactivation of Yos1p blocks transport between the ER and …

Fine-Scale Genetic Structure And Social Organization In Female White-Tailed Deer, Christopher E. Comer, John Kilgo, Gino D'Angelo, Travis Glenn, Karl Miller

Faculty Publications

Social behavior of white-tailed deer (Odocoileus virginianus) can have important management implications.

The formation of matrilineal social groups among female deer has been documented and management strategies have been proposed based on this well-developed social structure. Using radiocollared (n = 17) and hunter or vehicle- killed (n = 21) does, we examined spatial and genetic structure in white-tailed deer on a 7,000-ha portion of the

Savannah River Site in the upper Coastal Plain of South Carolina, USA. We used 14 microsatellite DNA loci to calculate pairwise relatedness among individual deer and to assign doe pairs to …

The Stepping Stone Model, Ii: Genealogies And The Infinite Sites Model, Submitted, Iljana Zähle, J. Theodore Cox, Richard Durrett

Mathematics - All Scholarship

This paper extends earlier work by Cox and Durrett, who studied the coalescence times for two lineages in the stepping stone model on the two-dimensional torus. We show that the genealogy of a sample of size n is given by a time change of Kingman’s coalescent. With DNA sequence data in mind, we investigate mutation patterns under the infinite sites model, which assumes that each mutation occurs at a new site. Our results suggest that the spatial structure of the human population contributes to the haplotype structure and a slower than expected decay of genetic correlation with distance revealed by …

Silencing Of Retrotransposons In Dictyostelium By Dna Methylation And Rnai, Markus Kuhlmann, Branimira E. Borisova, Markus Kaller, Pontus Larsson, Dirk Stach, Jianbo Na, Ludwig Eichinger, Frank Lyko, Victor Ambros, Fredrik Soderbom, Christian Hammann, Wolfgang Nellen

Dartmouth Scholarship

We have identified a DNA methyltransferase of the Dnmt2 family in Dictyostelium that was denominated DnmA. Expression of the dnmA gene is downregulated during the developmental cycle. Overall DNA methylation in Dictyostelium is ∼0.2% of the cytosine residues, which indicates its restriction to a limited set of genomic loci. Bisulfite sequencing of specific sites revealed that DnmA is responsible for methylation of mostly asymmetric C-residues in the retrotransposons DIRS-1 and Skipper. Disruption of the gene resulted in a loss of methylation and in increased transcription and mobilization of Skipper. Skipper transcription was also upregulated in strains that had genes encoding …

Identification Of Recql1 As A Holliday Junction Processing Enzyme In Human Cell Lines, Gary Leroy, Robert Carroll, Saw Kyin, Masayuki Seki, Michael D. Cole

Dartmouth Scholarship

Homologous recombination provides an effective way to repair DNA double-strand breaks (DSBs) and is required for genetic recombination. During the process of homologous recombination, a heteroduplex DNA structure, or a ‘Holliday junction’ (HJ), is formed. The movement, or branch migration, of this junction is necessary for recombination to proceed correctly. In prokaryotes, the RecQ protein or the RuvA/RuvB protein complex can promote ATP-dependent branch migration of Holliday junctions. Much less is known about the processing of Holliday junctions in eukaryotes. Here, we identify RecQL1 as a predominant ATP-dependent, HJ branch migrator present in human nuclear extracts. A reduction in the …

Crystal Structure Of The Gtpase Domain Of Rat Dynamin 1, Thomas F. Reubold, Susanne Eschenburg, Andreas Becker, Marilyn Leonard, Sandra L. Schmid, Richard B. Vallee, F. Jon Kull, Dietmar J. Manstein

Dartmouth Scholarship

Here, we present the 1.9-A crystal structure of the nucleotide-free GTPase domain of dynamin 1 from Rattus norvegicus. The structure corresponds to an extended form of the canonical GTPase fold observed in Ras proteins. Both nucleotide-binding switch motifs are well resolved, adopting conformations that closely resemble a GTP-bound state not previously observed for nucleotide-free GTPases. Two highly conserved arginines, Arg-66 and Arg-67, greatly restrict the mobility of switch I and are ideally positioned to relay information about the nucleotide state to other parts of the protein. Our results support a model in which switch I residue Arg-59 gates GTP binding …

2005 Nebraska Swine Report, Duane E. Reese

University of Nebraska-Lincoln Extension: Historical Materials

This publication was prepared by the staff in Animal Science and cooperating Departments for use in Extension, Teaching and Research programs. It deals with the results that were done in reproduction, breeding, health, genetics, nutrition, economics and housing of swine.

The Impact Of Genomics And Genetics On Wheat Quality Improvement, John Snape, Lesley Fish, David Leader, Robert Bradburne, Adrian Turner

Turkish Journal of Agriculture and Forestry

This paper discusses how genetic and genomic tools may be used to understand the genetical and molecular control of cereal quality and to develop tools for its manipulation by conventional and genetic engineering approaches. Comprehensive genetic maps are a first step in the genetical and molecular analysis of traits and these now allow the dissection of the genetical control of complex traits. As an example, data on the genetical control of grain protein content in UK winter wheats is presented. From a series of field trials, several potentially useful new QTLs were identified on chromosomes 2B, 5D, 6A, 6B, 7A …