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Articles 1 - 30 of 73
Full-Text Articles in Life Sciences
Regulation Of The Wnt/Wingless Receptor Lrp6/Arrow By The Deubiquitylating Complex Usp46, Zachary T. Spencer
Regulation Of The Wnt/Wingless Receptor Lrp6/Arrow By The Deubiquitylating Complex Usp46, Zachary T. Spencer
Dartmouth College Ph.D Dissertations
The evolutionarily conserved Wnt/Wingless signal transduction pathway is critical for the proper development of all animals and implicated in numerous diseases in adulthood. Upon binding of the Wnt/Wingless ligand, a cascade of events culminates in inactivation of the destruction complex, a negative regulator of the pathway, and the subsequent formation of singalosomes which mediate pathway activation. A critical component of signalosome formation is the Wnt/Wingless receptor LRP6/Arrow. Upon canonical pathway activation, LRP6/Arrow undergoes activation via phosphorylation by several kinases and complexes with another Wnt/Wingless receptor Frizzled, along with several cytoplasmic components. While many studies have investigated the regulatory mechanisms of …
Detecting Gene-Gene Interactions Using A Permutation-Based Random Forest Method, Jing Li, James D. Malley, Angeline S. Andrew, Margaret R. Karagas, Jason H. Moore
Detecting Gene-Gene Interactions Using A Permutation-Based Random Forest Method, Jing Li, James D. Malley, Angeline S. Andrew, Margaret R. Karagas, Jason H. Moore
Dartmouth Scholarship
Identifying gene-gene interactions is essential to understand disease susceptibility and to detect genetic architectures underlying complex diseases. Here, we aimed at developing a permutation-based methodology relying on a machine learning method, random forest (RF), to detect gene-gene interactions. Our approach called permuted random forest (pRF) which identified the top interacting single nucleotide polymorphism (SNP) pairs by estimating how much the power of a random forest classification model is influenced by removing pairwise interactions.
The Adp-Ribose Polymerase Tankyrase Regulates Adult Intestinal Stem Cell Proliferation During Homeostasis In Drosophila, Zhenghan Wang, Ai Tian, Hassina Benchabane, Ofelia Tacchelly-Benites, Eungi Yang, Hisashi Nojima, Yashi Ahmed
The Adp-Ribose Polymerase Tankyrase Regulates Adult Intestinal Stem Cell Proliferation During Homeostasis In Drosophila, Zhenghan Wang, Ai Tian, Hassina Benchabane, Ofelia Tacchelly-Benites, Eungi Yang, Hisashi Nojima, Yashi Ahmed
Dartmouth Scholarship
Wnt/β-catenin signaling controls intestinal stem cell (ISC) proliferation, and is aberrantly activated in colorectal cancer. Inhibitors of the ADP-ribose polymerase Tankyrase (Tnks) have become lead therapeutic candidates for Wnt-driven cancers, following the recent discovery that Tnks targets Axin, a negative regulator of Wnt signaling, for proteolysis. Initial reports indicated that Tnks is important for Wnt pathway activation in cultured human cell lines. However, the requirement for Tnks in physiological settings has been less clear, as subsequent studies in mice, fish and flies suggested that Tnks was either entirely dispensable for Wnt-dependent processes in vivo, or alternatively, had tissue-specific roles. Here, …
Development Of The Crispr/Cas9 System For Targeted Gene Disruption In Aspergillus Fumigatus, Kevin Fuller, Shan Chen, Jennifer J. Loros, Jay C. Dunlap
Development Of The Crispr/Cas9 System For Targeted Gene Disruption In Aspergillus Fumigatus, Kevin Fuller, Shan Chen, Jennifer J. Loros, Jay C. Dunlap
Dartmouth Scholarship
Low rates of homologous recombination have broadly encumbered genetic studies in the fungal pathogen Aspergillus fumigatus. The CRISPR/Cas9 system of bacteria has recently been developed for targeted mutagenesis of eukaryotic genomes with high effi- ciency and, importantly, through a mechanism independent of homologous repair machinery. As this new technology has not been developed for use in A. fumigatus, we sought to test its feasibility for targeted gene disruption in this organism. As a proof of principle, we first demonstrated that CRISPR/Cas9 can indeed be used for high-efficiency (25 to 53%) targeting of the A. fu- migatus polyketide synthase gene (pksP), …
Polyq-Dependent Rna–Protein Assemblies Control Symmetry Breaking, Changhwan Lee, Patricia Occhipinti, Amy S. Gladfelter
Polyq-Dependent Rna–Protein Assemblies Control Symmetry Breaking, Changhwan Lee, Patricia Occhipinti, Amy S. Gladfelter
Dartmouth Scholarship
Dendritic growth in fungi and neurons requires that multiple axes of polarity are established and maintained within the same cytoplasm. We have discovered that transcripts encoding key polarity factors including a formin, Bni1, and a polarisome scaffold, Spa2, are nonrandomly clustered in the cytosol to initiate and maintain sites of polarized growth in the fungus Ashbya gossypii. This asymmetric distribution requires the mRNAs to interact with a polyQ-containing protein, Whi3, and a Pumilio protein with a low-complexity sequence, Puf2. Cells lacking Whi3 or Puf2 had severe defects in establishing new sites of polarity and failed to localize Bni1 protein. Interaction …
A Classification And Characterization Of Two-Locus, Pure, Strict, Epistatic Models For Simulation And Detection, Ryan J. Urbanowicz, Ambrose L. S. Granizo-Mackenzie, Jeff Kiralis, Jason H Moore
A Classification And Characterization Of Two-Locus, Pure, Strict, Epistatic Models For Simulation And Detection, Ryan J. Urbanowicz, Ambrose L. S. Granizo-Mackenzie, Jeff Kiralis, Jason H Moore
Dartmouth Scholarship
BackgroundThe statistical genetics phenomenon of epistasis is widely acknowledged to confound disease etiology. In order to evaluate strategies for detecting these complex multi-locus disease associations, simulation studies are required. The development of the GAMETES software for the generation of complex genetic models, has provided the means to randomly generate an architecturally diverse population of epistatic models that are both pure and strict, i.e. all n loci, but no fewer, are predictive of phenotype. Previous theoretical work characterizing complex genetic models has yet to examine pure, strict, epistasis which should be the most challenging to detect. This study addresses three goals: …
Deletion Mutant Library For Investigation Of Functional Outputs Of Cyclic Diguanylate Metabolism In Pseudomonas Aeruginosa Pa14, Dae-Gon Ha, Megan E. Richman, George A. O'Toole
Deletion Mutant Library For Investigation Of Functional Outputs Of Cyclic Diguanylate Metabolism In Pseudomonas Aeruginosa Pa14, Dae-Gon Ha, Megan E. Richman, George A. O'Toole
Dartmouth Scholarship
We constructed a library of in-frame deletion mutants targeting each gene in Pseudomonas aeruginosa PA14 predicted to participate in cyclic di-GMP (c-di-GMP) metabolism (biosynthesis or degradation) to provide a toolkit to assist investigators studying c-di-GMP-mediated regulation by this microbe. We present phenotypic assessments of each mutant, including biofilm formation, exopolysaccharide (EPS) production, swimming motility, swarming motility, and twitch motility, as a means to initially characterize these mutants and to demonstrate the potential utility of this library.
How To Get The Most From Microarray Data: Advice From Reverse Genomics, Ivan P. Gorlov, Ji-Yeon Yang, Jinyoung Byun, Christopher Logothetis, Olga Y. Gorlova, Kim-Anh Do, Christopher Amos
How To Get The Most From Microarray Data: Advice From Reverse Genomics, Ivan P. Gorlov, Ji-Yeon Yang, Jinyoung Byun, Christopher Logothetis, Olga Y. Gorlova, Kim-Anh Do, Christopher Amos
Dartmouth Scholarship
Whole-genome profiling of gene expression is a powerful tool for identifying cancer-associated genes. Genes differentially expressed between normal and tumorous tissues are usually considered to be cancer associated. We recently demonstrated that the analysis of interindividual variation in gene expression can be useful for identifying cancer associated genes. The goal of this study was to identify the best microarray data–derived predictor of known cancer associated genes. We found that the traditional approach of identifying cancer genes—identifying differentially expressed genes—is not very efficient. The analysis of interindividual variation of gene expression in tumor samples identifies cancer-associated genes more effectively. The results …
Gene And Protein Sequence Optimization For High-Level Production Of Fully Active And Aglycosylated Lysostaphin In Pichia Pastoris, Hongliang Zhao, Kristina Blazanovic, Yoonjoo Choi, Chris Bailey-Kellogg, Karl E. Griswold
Gene And Protein Sequence Optimization For High-Level Production Of Fully Active And Aglycosylated Lysostaphin In Pichia Pastoris, Hongliang Zhao, Kristina Blazanovic, Yoonjoo Choi, Chris Bailey-Kellogg, Karl E. Griswold
Dartmouth Scholarship
Lysostaphin represents a promising therapeutic agent for the treatment of staphylococcal infections, in particular those of methicillin-resistant Staphylococcus aureus (MRSA). However, conventional expression systems for the enzyme suffer from various limitations, and there remains a need for an efficient and cost-effective production process to facilitate clinical translation and the development of nonmedical applications. While Pichia pastoris is widely used for high-level production of recombinant proteins, there are two major barriers to the production of lysostaphin in this industrially relevant host: lack of expression from the wild-type lysostaphin gene and aberrant glycosylation of the wild-type protein sequence. The first barrier can …
Trip/Nopo E3 Ubiquitin Ligase Promotes Ubiquitylation Of Dna Polymerase Η, Heather A. Wallace, Julie A. Merkle, Michael C. Yu, Taloa G. Berg, Ethan Lee, Giovanni Bosco, Laura A. Lee
Trip/Nopo E3 Ubiquitin Ligase Promotes Ubiquitylation Of Dna Polymerase Η, Heather A. Wallace, Julie A. Merkle, Michael C. Yu, Taloa G. Berg, Ethan Lee, Giovanni Bosco, Laura A. Lee
Dartmouth Scholarship
We previously identified a Drosophila maternal effect-lethal mutant named ‘no poles’ (nopo). Embryos from nopo females undergo mitotic arrest with barrel-shaped, acentrosomal spindles during the rapid cycles of syncytial embryogenesis because of activation of a Chk2-mediated DNA checkpoint. NOPO is the Drosophila homolog of human TNF receptor associated factor (TRAF)-interacting protein (TRIP), which has been implicated in TNF signaling. NOPO and TRIP contain RING domains closely resembling those of known E3 ubiquitin ligases. We herein sought to elucidate the mechanism by which TRIP/NOPO promotes genomic stability by performing a yeast two-hybrid screen to identify potential substrates/interactors. We identified members of …
Reactin: Regulatory Activity Inference Of Transcription Factors Underlying Human Diseases With Application To Breast Cancer, Mingzhu Zhu, Chun-Chi Liu, Chao Cheng
Reactin: Regulatory Activity Inference Of Transcription Factors Underlying Human Diseases With Application To Breast Cancer, Mingzhu Zhu, Chun-Chi Liu, Chao Cheng
Dartmouth Scholarship
Genetic alterations of transcription factors (TFs) have been implicated in the tumorigenesis of cancers. In many cancers, alteration of TFs results in aberrant activity of them without changing their gene expression level. Gene expression data from microarray or RNA-seq experiments can capture the expression change of genes, however, it is still challenge to reveal the activity change of TFs. Here we propose a method, called REACTIN (REgulatory ACTivity INference), which integrates TF binding data with gene expression data to identify TFs with significantly differential activity between disease and normal samples. REACTIN successfully detect differential activity of estrogen receptor (ER) between …
Differential Regulation Of White-Opaque Switching By Individual Subunits Of Candida Albicans Mediator, Anda Zhang, Zhongle Liu, Lawrence C. Myers
Differential Regulation Of White-Opaque Switching By Individual Subunits Of Candida Albicans Mediator, Anda Zhang, Zhongle Liu, Lawrence C. Myers
Dartmouth Scholarship
The multisubunit eukaryotic Mediator complex integrates diverse positive and negative gene regulatory signals and transmits them to the core transcription machinery. Mutations in individual subunits within the complex can lead to decreased or increased transcription of certain subsets of genes, which are highly specific to the mutated subunit. Recent studies suggest a role for Mediator in epigenetic silencing. Using white-opaque morphological switching in Candida albicans as a model, we have shown that Mediator is required for the stability of both the epigenetic silenced (white) and active (opaque) states of the bistable transcription circuit driven by the master regulator Wor1. Individual …
Atypical Glycolysis In Clostridium Thermocellum, Jilai Zhou, Daniel G. Olson, D. Aaron Argyros, Yu Deng, Walter M. Van Gulik, Johannes P. Van Dijken, Lee R. Lynd
Atypical Glycolysis In Clostridium Thermocellum, Jilai Zhou, Daniel G. Olson, D. Aaron Argyros, Yu Deng, Walter M. Van Gulik, Johannes P. Van Dijken, Lee R. Lynd
Dartmouth Scholarship
Cofactor specificities of glycolytic enzymes in Clostridium thermocellum were studied with cellobiose-grown cells from batch cultures. Intracellular glucose was phosphorylated by glucokinase using GTP rather than ATP. Although phosphofructokinase typically uses ATP as a phosphoryl donor, we found only pyrophosphate (PPi)-linked activity. Phosphoglycerate kinase used both GDP and ADP as phosphoryl acceptors. In agreement with the absence of a pyruvate kinase sequence in the C. thermocellum genome, no activity of this enzyme could be detected. Also, the annotated pyruvate phosphate dikinase (ppdk) is not crucial for the generation of pyruvate from phosphoenolpyruvate (PEP), as deletion of the ppdk gene did …
Septin Phosphorylation And Coiled-Coil Domains Function In Cell And Septin Ring Morphology In The Filamentous Fungus Ashbya Gossypii, Rebecca A. Meseroll, Patricia Occhipinti, Amy S. Gladfelter
Septin Phosphorylation And Coiled-Coil Domains Function In Cell And Septin Ring Morphology In The Filamentous Fungus Ashbya Gossypii, Rebecca A. Meseroll, Patricia Occhipinti, Amy S. Gladfelter
Dartmouth Scholarship
Septins are a class of GTP-binding proteins conserved throughout many eukaryotes. Individual septin subunits associate with one another and assemble into heteromeric complexes that form filaments and higher-order structures in vivo. The mechanisms underlying the assembly and maintenance of higher-order structures in cells remain poorly understood. Septins in several organisms have been shown to be phosphorylated, although precisely how septin phosphorylation may be contributing to the formation of high-order septin structures is unknown. Four of the five septins expressed in the filamentous fungus, Ashbya gossypii, are phosphorylated, and we demonstrate here the diverse roles of these phosphorylation sites …
Characterization Of Xylan Utilization And Discovery Of A New Endoxylanase In Thermoanaerobacterium Saccharolyticum Through Targeted Gene Deletions, Kara K. Podkaminer, Adam M. Guss, Heather L. Trajano, David A. Hogsett, Lee R. Lynd
Characterization Of Xylan Utilization And Discovery Of A New Endoxylanase In Thermoanaerobacterium Saccharolyticum Through Targeted Gene Deletions, Kara K. Podkaminer, Adam M. Guss, Heather L. Trajano, David A. Hogsett, Lee R. Lynd
Dartmouth Scholarship
The economical production of fuels and commodity chemicals from lignocellulose requires the utilization of both the cellulose and hemicellulose fractions. Xylanase enzymes allow greater utilization of hemicellulose while also increasing cellulose hydrolysis. Recent metabolic engineering efforts have resulted in a strain of Thermoanaerobacterium saccharolyticum that can convert C5 and C6 sugars, as well as insoluble xylan, into ethanol at high yield. To better understand the process of xylan solubilization in this organism, a series of targeted deletions were constructed in the homoethanologenic T. saccharolyticum strain M0355 to characterize xylan hydrolysis and xylose utilization in this organism. While the deletion of …
Farnesol And Cyclic Amp Signaling Effects On The Hypha-To-Yeast Transition In Candida Albicans, Allia K. Lindsay, Aurélie Deveau, Amy E. Piispanen, Deborah A. Hogan
Farnesol And Cyclic Amp Signaling Effects On The Hypha-To-Yeast Transition In Candida Albicans, Allia K. Lindsay, Aurélie Deveau, Amy E. Piispanen, Deborah A. Hogan
Dartmouth Scholarship
Candida albicans, a fungal pathogen of humans, regulates its morphology in response to many environmental cues and this morphological plasticity contributes to virulence. Farnesol, an autoregulatory molecule produced by C. albicans, inhibits the induction of hyphal growth by inhibiting adenylate cyclase (Cyr1). The role of farnesol and Cyr1 in controlling the maintenance of hyphal growth has been less clear. Here, we demonstrate that preformed hyphae transition to growth as yeast in response to farnesol and that strains with increased cyclic AMP (cAMP) signaling exhibit more resistance to farnesol. Exogenous farnesol did not induce the hypha-to-yeast transition in mutants …
Condensin Ii Promotes The Formation Of Chromosome Territories By Inducing Axial Compaction Of Polyploid Interphase Chromosomes, Christopher R. R. Bauer, Tom A. Hartl, Giovanni Bosco
Condensin Ii Promotes The Formation Of Chromosome Territories By Inducing Axial Compaction Of Polyploid Interphase Chromosomes, Christopher R. R. Bauer, Tom A. Hartl, Giovanni Bosco
Dartmouth Scholarship
The eukaryotic nucleus is both spatially and functionally partitioned. This organization contributes to the maintenance, expression, and transmission of genetic information. Though our ability to probe the physical structure of the genome within the nucleus has improved substantially in recent years, relatively little is known about the factors that regulate its organization or the mechanisms through which specific organizational states are achieved. Here, we show that Drosophila melanogaster Condensin II induces axial compaction of interphase chromosomes, globally disrupts interchromosomal interactions, and promotes the dispersal of peri-centric heterochromatin. These Condensin II activities compartmentalize the nucleus into discrete chromosome territories and indicate …
Gene Ontology Analysis Of Pairwise Genetic Associations In Two Genome-Wide Studies Of Sporadic Als, Nora Chung Kim, Peter C. Andrews, Folkert W. Asselbergs, H Robert Frost, Scott M. Williams, Brent T. Harris, Cynthia Read, Kathleen D. Askland, Jason H. Moore
Gene Ontology Analysis Of Pairwise Genetic Associations In Two Genome-Wide Studies Of Sporadic Als, Nora Chung Kim, Peter C. Andrews, Folkert W. Asselbergs, H Robert Frost, Scott M. Williams, Brent T. Harris, Cynthia Read, Kathleen D. Askland, Jason H. Moore
Dartmouth Scholarship
It is increasingly clear that common human diseases have a complex genetic architecture characterized by both additive and nonadditive genetic effects. The goal of the present study was to determine whether patterns of both additive and nonadditive genetic associations aggregate in specific functional groups as defined by the Gene Ontology (GO).
Two Boundaries Separate Borrelia Burgdorferi Populations In North America, Gabriele Margos, Jean I. Tsao, Santiago Castillo-Ramirez, Yvette A. Girard, Anne G. Hoen
Two Boundaries Separate Borrelia Burgdorferi Populations In North America, Gabriele Margos, Jean I. Tsao, Santiago Castillo-Ramirez, Yvette A. Girard, Anne G. Hoen
Dartmouth Scholarship
Understanding the spread of infectious diseases is crucial for implementing effective control measures. For this, it is important to obtain information on the contemporary population structure of a disease agent and to infer the evolutionary processes that may have shaped it. Here, we investigate on a continental scale the population structure of Borrelia burgdorferi, the causative agent of Lyme borreliosis (LB), a tick-borne disease, in North America. We test the hypothesis that the observed d population structure is congruent with recent population expansions and that these were preceded by bottlenecks mostly likely caused by the near extirpation in the 1900s …
Computational Design And Characterization Of A Temperature-Sensitive Plasmid Replicon For Gram Positive Thermophiles, Daniel G. Olson, Lee R. Lynd
Computational Design And Characterization Of A Temperature-Sensitive Plasmid Replicon For Gram Positive Thermophiles, Daniel G. Olson, Lee R. Lynd
Dartmouth Scholarship
Temperature-sensitive (Ts) plasmids are useful tools for genetic engineering, but there are currently none compatible with the gram positive, thermophilic, obligate anaerobe, Clostridium thermocellum. Traditional mutagenesis techniques yield Ts mutants at a low frequency, and therefore requires the development of high-throughput screening protocols, which are also not available for this organism. Recently there has been progress in the development of computer algorithms which can predict Ts mutations. Most plasmids currently used for genetic modification of C. thermocellum are based on the replicon of plasmid pNW33N, which replicates using the RepB replication protein. To address this problem, we set out …
Dna Methylation Arrays As Surrogate Measures Of Cell Mixture Distribution, Eugene Houseman, William P. Accomando, Devin C. Koestler, Brock C. Christensen, Carmen J. Marsit
Dna Methylation Arrays As Surrogate Measures Of Cell Mixture Distribution, Eugene Houseman, William P. Accomando, Devin C. Koestler, Brock C. Christensen, Carmen J. Marsit
Dartmouth Scholarship
There has been a long-standing need in biomedical research for a method that quantifies the normally mixed composition of leukocytes beyond what is possible by simple histological or flow cytometric assessments. The latter is restricted by the labile nature of protein epitopes, requirements for cell processing, and timely cell analysis. In a diverse array of diseases and following numerous immune-toxic exposures, leukocyte composition will critically inform the underlying immuno-biology to most chronic medical conditions. Emerging research demonstrates that DNA methylation is responsible for cellular differentiation, and when measured in whole peripheral blood, serves to distinguish cancer cases from controls.
The Tlo Proteins Are Stoichiometric Components Of Candida Albicans Mediator Anchored Via The Med3 Subunit, Anda Zhang, Kostadin O. Petrov, Emily R. Hyun, Zhongle Liu, Scott A. Gerber, Lawrence C. Myers
The Tlo Proteins Are Stoichiometric Components Of Candida Albicans Mediator Anchored Via The Med3 Subunit, Anda Zhang, Kostadin O. Petrov, Emily R. Hyun, Zhongle Liu, Scott A. Gerber, Lawrence C. Myers
Dartmouth Scholarship
The amplification of the TLO (for telomere-associated) genes in Candida albicans, compared to its less pathogenic, close relative Candida dubliniensis, suggests a role in virulence. Little, however, is known about the function of the Tlo proteins. We have purified the Mediator coactivator complex from C. albicans (caMediator) and found that Tlo proteins are a stoichiometric component of caMediator. Many members of the Tlo family are expressed, and each is a unique member of caMediator. Protein expression analysis of individual Tlo proteins, as well as the purification of tagged Tlo proteins, demonstrate that there is a large free population of Tlo …
Heterogeneity In Mitochondrial Morphology And Membrane Potential Is Independent Of The Nuclear Division Cycle In Multinucleate Fungal Cells, John P. Gerstenberger, Patricia Occhipinti, Amy S. Gladfelter
Heterogeneity In Mitochondrial Morphology And Membrane Potential Is Independent Of The Nuclear Division Cycle In Multinucleate Fungal Cells, John P. Gerstenberger, Patricia Occhipinti, Amy S. Gladfelter
Dartmouth Scholarship
In the multinucleate filamentous fungus Ashbya gossypii, nuclei divide asynchronously in a common cytoplasm. We hypothesize that the division cycle machinery has a limited zone of influence in the cytoplasm to promote nuclear autonomy. Mitochondria in cultured mammalian cells undergo cell cycle-specific changes in morphology and membrane potential and therefore can serve as a reporter of the cell cycle state of the cytoplasm. To evaluate if the cell cycle state of nuclei in A. gossypii can influ
Erect Wing Facilitates Context-Dependent Wnt/Wingless Signaling By Recruiting The Cell-Specific Armadillo-Tcf Adaptor Earthbound To Chromatin, Nan Xin, Hassina Benchabane, Ai Tian, Kerrie Nguyen, Lindsay Klofas, Yashi Ahmed
Erect Wing Facilitates Context-Dependent Wnt/Wingless Signaling By Recruiting The Cell-Specific Armadillo-Tcf Adaptor Earthbound To Chromatin, Nan Xin, Hassina Benchabane, Ai Tian, Kerrie Nguyen, Lindsay Klofas, Yashi Ahmed
Dartmouth Scholarship
During metazoan development, the Wnt/Wingless signal transduction pathway is activated repetitively to direct cell proliferation, fate specification, differentiation and apoptosis. Distinct outcomes are elicited by Wnt stimulation in different cellular contexts; however, mechanisms that confer context specificity to Wnt signaling responses remain largely unknown. Starting with an unbiased forward genetic screen in Drosophila, we recently uncovered a novel mechanism by which the cell-specific co-factor Earthbound 1 (Ebd1), and its human homolog jerky, promote interaction between the Wnt pathway transcriptional co-activators B-catenin/Armadillo and TCF to facilitate context-dependent Wnt signaling responses. Here, through the same genetic screen, we find an unanticipated requirement …
Axl2 Integrates Polarity Establishment, Maintenance, And Environmental Stress Response In The Filamentous Fungus Ashbya Gossypii, Jonathan F. Anker, Amy S. Gladfelter
Axl2 Integrates Polarity Establishment, Maintenance, And Environmental Stress Response In The Filamentous Fungus Ashbya Gossypii, Jonathan F. Anker, Amy S. Gladfelter
Dartmouth Scholarship
In budding yeast, new sites of polarity are chosen with each cell cycle and polarization is transient. In filamentous fungi, sites of polarity persist for extended periods of growth and new polarity sites can be established while existing sites are maintained. How the polarity establishment machinery functions in these distinct growth forms found in fungi is still not well understood. We have examined the function of Axl2, a transmembrane bud site selection protein discovered in Saccharomyces cerevisiae, in the filamentous fungus Ashbya gossypii. A. gossypii does not divide by budding and instead exhibits persistent highly polarized growth, and multiple axes …
High Ethanol Titers From Cellulose By Using Metabolically Engineered Thermophilic, Anaerobic Microbes, D. Aaron Argyros, Shital A. Tripathi, Trisha F. Barrett, Stephen R. Rogers, Lawrence F. Feinberg, Daniel G. Olson, Justin M. Foden, Bethany B. Miller, Lee R. Lynd, David A. Hogsett, Nicky C. Caiazza
High Ethanol Titers From Cellulose By Using Metabolically Engineered Thermophilic, Anaerobic Microbes, D. Aaron Argyros, Shital A. Tripathi, Trisha F. Barrett, Stephen R. Rogers, Lawrence F. Feinberg, Daniel G. Olson, Justin M. Foden, Bethany B. Miller, Lee R. Lynd, David A. Hogsett, Nicky C. Caiazza
Dartmouth Scholarship
This work describes novel genetic tools for use in Clostridium thermocellum that allow creation of unmarked mutations while using a replicating plasmid. The strategy employed counter-selections developed from the native C. thermocellum hpt gene and the Thermoanaerobacterium saccharolyticum tdk gene and was used to delete the genes for both lactate dehydrogenase (Ldh) and phosphotransacetylase (Pta). The Δldh Δpta mutant was evolved for 2,000 h, resulting in a stable strain with 40:1 ethanol selectivity and a 4.2-fold increase in ethanol yield over the wild-type strain. Ethanol production from cellulose was investigated with an engineered coculture of organic acid-deficient engineered strains of …
Global Analysis Of Serine-Threonine Protein Kinase Genes In Neurospora Crassa, Gyungsoon Park, Jacqueline A. Servin, Gloria E. Turner, Lorena Altamirano
Global Analysis Of Serine-Threonine Protein Kinase Genes In Neurospora Crassa, Gyungsoon Park, Jacqueline A. Servin, Gloria E. Turner, Lorena Altamirano
Dartmouth Scholarship
Serine/threonine (S/T) protein kinases are crucial components of diverse signaling pathways in eukaryotes, including the model filamentous fungus Neurospora crassa. In order to assess the importance of S/T kinases to Neurospora biology, we embarked on a global analysis of 86 S/T kinase genes in Neurospora. We were able to isolate viable mutants for 77 of the 86 kinase genes. Of these, 57% exhibited at least one growth or developmental phenotype, with a relatively large fraction (40%) possessing a defect in more than one trait. S/T kinase knockouts were subjected to chemical screening using a panel of eight chemical treatments, with …
Ecology And Genetic Structure Of A Northern Temperate Vibrio Cholerae Population Related To Toxigenic Isolates, Brian M. Schuster, Anna L. Tyzik, Rachel A. Donner, Megan J. Striplin, Salvador Almagro-Moreno
Ecology And Genetic Structure Of A Northern Temperate Vibrio Cholerae Population Related To Toxigenic Isolates, Brian M. Schuster, Anna L. Tyzik, Rachel A. Donner, Megan J. Striplin, Salvador Almagro-Moreno
Dartmouth Scholarship
Although Vibrio cholerae is an important human pathogen, little is known about its populations in regions where the organism is endemic but where cholera disease is rare. A total of 31 independent isolates confirmed as V. cholerae were collected from water, sediment, and oysters in 2008 and 2009 from the Great Bay Estuary (GBE) in New Hampshire, a location where the organism has never been detected. Environmental analyses suggested that abundance correlates most strongly with rainfall events, as determined from data averaged over several days prior to collection. Phenotyping, genotyping, and multilocus sequence analysis (MLSA) revealed a highly diverse endemic …
Roles Of Ras1 Membrane Localization During Candida Albicans Hyphal Growth And Farnesol Response, Amy E. Piispanen, Ophelie Bonnefoi, Sarah Carden, Aurelie Deveau
Roles Of Ras1 Membrane Localization During Candida Albicans Hyphal Growth And Farnesol Response, Amy E. Piispanen, Ophelie Bonnefoi, Sarah Carden, Aurelie Deveau
Dartmouth Scholarship
Many Ras GTPases localize to membranes via C-terminal farnesylation and palmitoylation, and localization regulates function. In Candida albicans, a fungal pathogen of humans, Ras1 links environmental cues to morphogenesis. Here, we report the localization and membrane dynamics of Ras1, and we characterize the roles of conserved C-terminal cysteine residues, C287 and C288, which are predicted sites of palmitoylation and farnesylation, respectively. GFP-Ras1 is localized uniformly to plasma membranes in both yeast and hyphae, yet Ras1 plasma membrane mobility was reduced in hyphae compared to that in yeast. Ras1-C288S was mislocalized to the cytoplasm and could not support hyphal development. …
Type Ii Toxoplasma Gondii Ku80 Knockout Strains Enable Functional Analysis Of Genes Required For Cyst Development And Latent Infection, Barbara A. Fox, Alejandra Falla, Leah M. Rommereim, Tadakimi Tomita
Type Ii Toxoplasma Gondii Ku80 Knockout Strains Enable Functional Analysis Of Genes Required For Cyst Development And Latent Infection, Barbara A. Fox, Alejandra Falla, Leah M. Rommereim, Tadakimi Tomita
Dartmouth Scholarship
Type II Toxoplasma gondii KU80 knockouts (Δku80) deficient in nonhomologous end joining were developed to delete the dominant pathway mediating random integration of targeting episomes. Gene targeting frequency in the type II Δku80 Δhxgprt strain measured at the orotate (OPRT) and the uracil (UPRT) phosphoribosyltransferase loci was highly efficient. To assess the potential of the type II Δku80 Δhxgprt strain to examine gene function affecting cyst biology and latent stages of infection, we targeted the deletion of four parasite antigen genes (GRA4, GRA6, ROP7, and tgd057 …