Life Sciences Commons^™

H-Ns Binding And Repression Of The Ctx Promoter In Vibrio Cholerae, Emily A. Stonehouse, Robin R. Hulbert, Melinda B. Nye, Karen Skorupski, Ronald K. Taylor

Dartmouth Scholarship

Expression of the ctx and tcp genes, which encode cholera toxin and the toxin coregulated pilus, the Vibrio cholerae O1 virulence determinants having the largest contribution to cholera disease, is repressed by the nucleoid-associated protein H-NS and activated by the AraC-like transcriptional regulator ToxT. To elucidate the molecular mechanism by which H-NS controls transcription of the ctxAB operon, H-NS repression and binding were characterized by using a promoter truncation series, gel mobility shift assays, and DNase I footprinting. Promoter regions found to be important for H-NS repression correlated with in vitro binding. Four main H-NS binding regions are present at …

Excision Dynamics Of Vibrio Pathogenicity Island-2 From Vibrio Cholerae: Role Of A Recombination Directionality Factor Vefa, Salvador Almagro-Moreno, Michael G. Napolitano, E. Fidelma Boyd

Dartmouth Scholarship

Vibrio Pathogenicity Island-2 (VPI-2) is a 57 kb region present in choleragenic V. cholerae isolates that is required for growth on sialic acid as a sole carbon source. V. cholerae non-O1/O139 pathogenic strains also contain VPI-2, which in addition to sialic acid catabolism genes also encodes a type 3 secretion system in these strains. VPI-2 integrates into chromosome 1 at a tRNA-serine site and encodes an integrase intV2 (VC1758) that belongs to the tyrosine recombinase family. ntV2 is required for VPI-2 excision from chromosome 1, which occurs at very low levels, and formation of a non-replicative circular intermediate.

The Combined Effect Of Environmental And Host Factors On The Emergence Of Viral Rna Recombinants, Hannah M. Jaag, Peter D. Nagy

Plant Pathology Faculty Publications

Viruses are masters of evolution due to high frequency mutations and genetic recombination. In spite of the significance of viral RNA recombination that promotes the emergence of drug-resistant virus strains, the role of host and environmental factors in RNA recombination is poorly understood. Here we report that the host Met22p/Hal2p bisphosphate-3'-nucleotidase regulates the frequency of viral RNA recombination and the efficiency of viral replication. Based on Tomato bushy stunt virus (TBSV) and yeast as a model host, we demonstrate that deletion of MET22 in yeast or knockdown of AHL, SAL1 and FRY1 nucleotidases/phosphatases in plants leads to increased TBSV recombination …

Quantitative Trait Loci Mapping Reveals Candidate Pathways Regulating Cell Cycle Duration In Plasmodium Falciparum, Heather B. Reilly Ayala, Mark A. Wacker, Geoffrey Siwo, Michael T. Ferdig

Faculty Publications - Department of Biological & Molecular Science

Background: Elevated parasite biomass in the human red blood cells can lead to increased malaria morbidity. The genes and mechanisms regulating growth and development of Plasmodium falciparum through its erythrocytic cycle are not well understood. We previously showed that strains HB3 and Dd2 diverge in their proliferation rates, and here use quantitative trait loci mapping in 34 progeny from a cross between these parent clones along with integrative bioinformatics to identify genetic loci and candidate genes that control divergences in cell cycle duration. Results: Genetic mapping of cell cycle duration revealed a four-locus genetic model, including a major genetic effect …

Physical Interaction Between Vivid And White Collar Complex Regulates Photoadaptation In Neurospora, Chen-Hui H. Chen, Bradley S. Demay, Amy S. Gladfelter, Jay Dunlap, Jennifer J. Loros

Dartmouth Scholarship

Photoadaptation, the ability to attenuate a light response on prolonged light exposure while remaining sensitive to escalating changes in light intensity, is essential for organisms to decipher time information appropriately, yet the underlying molecular mechanisms are poorly understood. In Neurospora crassa, VIVID (VVD), a small LOV domain containing blue-light photoreceptor protein, affects photoadaptation for most if not all light-responsive genes. We report that there is a physical interaction between VVD and the white collar complex (WCC), the primary blue-light photoreceptor and the transcription factor complex that initiates light-regulated transcriptional responses in Neurospora. Using two previously characterized VVD mutants, we show …

Sialic Acid Transport And Catabolism Are Cooperatively Regulated By Siar And Crp In Nontypeable Haemophilus Influenzae, Jason W. Johnston, Haider Shamsulddin, Anne-Frances Miller, Michael A. Apicella

Microbiology, Immunology, and Molecular Genetics Faculty Publications

BACKGROUND: The transport and catabolism of sialic acid, a critical virulence factor for nontypeable Haemophilus influenzae, is regulated by two transcription factors, SiaR and CRP.

RESULTS: Using a mutagenesis approach, glucosamine-6-phosphate (GlcN-6P) was identified as a co-activator for SiaR. Evidence for the cooperative regulation of both the sialic acid catabolic and transport operons suggested that cooperativity between SiaR and CRP is required for regulation. cAMP was unable to influence the expression of the catabolic operon in the absence of SiaR but was able to induce catabolic operon expression when both SiaR and GlcN-6P were present. Alteration of helical phasing supported …

Bpab, A Novel Protein Encoded By The Lyme Disease Spirochete's Cp32 Prophages, Binds To Erp Operator 2 Dna, Logan H. Burns, Claire A. Adams, Sean P. Riley, Brandon L. Jutras, Amy Bowman, Alicia M. Chenail, Anne E. Cooley, Laura A. Haselhorst, Alisha M. Moore, Kelly Babb, Michael G. Fried, Brian Stevenson

Microbiology, Immunology, and Molecular Genetics Faculty Publications

Borrelia burgdorferi produces Erp outer surface proteins throughout mammalian infection, but represses their synthesis during colonization of vector ticks. A DNA region 5′ of the start of erp transcription, Operator 2, was previously shown to be essential for regulation of expression. We now report identification and characterization of a novel erp Operator 2-binding protein, which we named BpaB. erp operons are located on episomal cp32 prophages, and a single bacterium may contain as many as 10 different cp32s. Each cp32 family member encodes a unique BpaB protein, yet the three tested cp32-encoded BpaB alleles all bound to the same DNA …

Natural Competence In Thermoanaerobacter And Thermoanaerobacterium Species, A Joe Shaw, David A. Hogsett, Lee R. Lynd

Dartmouth Scholarship

Low-G+C thermophilic obligate anaerobes in the class Clostridia are considered among the bacteria most resistant to genetic engineering due to the difficulty of introducing foreign DNA, thus limiting the ability to study and exploit their native hydrolytic and fermentative capabilities. Here, we report evidence of natural genetic competence in 13 Thermoanaerobacter and Thermoanaerobacterium strains previously believed to be difficult to transform or genetically recalcitrant.

In Thermoanaerobacterium saccharolyticum JW/SL-YS485, natural competence- mediated DNA incorporation occurs during the exponential growth phase with both replicating plasmid and homologous recombination-based integration, and circular or linear DNA. In T. saccharolyticum, disruptions of genes similar to …

Oas1 Polymorphisms Are Associated With Susceptibility To West Nile Encephalitis In Horses, Jonathan J. Rios, Joann G. W. Fleming, Uneeda K. Bryant, Craig N. Carter, John C. Huber Jr., Maureen T. Long, Thomas E. Spencer, David L. Adelson

Veterinary Diagnostic Laboratory Faculty Publications

West Nile virus, first identified within the United States in 1999, has since spread across the continental states and infected birds, humans and domestic animals, resulting in numerous deaths. Previous studies in mice identified the Oas1b gene, a member of the OAS/RNASEL innate immune system, as a determining factor for resistance to West Nile virus (WNV) infection. A recent case-control association study described mutations of human OAS1 associated with clinical susceptibility to WNV infection. Similar studies in horses, a particularly susceptible species, have been lacking, in part, because of the difficulty in collecting populations sufficiently homogenous in their infection and …

Morphological And Genetic Analyses In The Melanoplus Packardii Group (Orthoptera: Acrididae), Mathew L. Brust, Erica J. Lindroth, W. Wyatt Hoback, Robert Wright, Kathryn J. Hanford, John E. Foster

Department of Entomology: Faculty Publications

Melanoplus packardii Scudder was described in 1897. Three additional closely-related species were later described and their status as species has been questioned on numerous occasions. We examined morphology from specimens collected in Nebraska which fit descriptions of three of the four forms and specimens that appeared to be hybrids. We found distinct morphological characters suggesting species status for M. foedus and M. packardii, but not for M. foedus fluviatilis. Examination of aedeagi of these three forms suggests that M. foedus and M. packardii are each distinct, but that the aedeagi of M. f. fluviatilis and M. f. foedus cannot …

Genetic Adult Lactase Persistence Is Associated With Risk Of Crohn's Disease In A New Zealand Population, Deborah Nolan, Dug Yeo Han, Wen Jiun Lam, Angharad R. Morgan, Alan G. Fraser, Linda C. Tapsell, Lynnette R. Ferguson

Faculty of Health and Behavioural Sciences - Papers (Archive)

Background Mycobacterium avium subspecies paratuberculosis (MAP) is an infective agent found in ruminants and milk products, which has been suggested to increase the risk of gastrointestinal inflammation in genetically susceptible hosts. It is hypothesized that lactase persistence facilitates exposure to such milk products increasing the likelihood of adverse outcomes. Individuals either homozygous or heterozygous for the T allele of DNA variant, rs4988235, located 14kb upstream from the LCT locus, are associated with having lactase persistence. The aim of this study was to determine whether lactase persistence as evident by the T allele of rs4988235 is associated with Crohn’s Disease (CD) …

Genetic Structure And Dispersal Patterns Of The Invasive Psocid Liposcelis Decolor (Pearman) In Australian Grain Storage Systems, Katarina Maryann Mikac, N N. Fitzsimmons

Faculty of Science - Papers (Archive)

Microsatellite markers were used to investigate the genetic structure among invasive L. decolor populations from Australia and a single international population from Kansas, USA to determine patterns of dispersal. Six variable microsatellites displayed an average of 2.5-4.2 alleles per locus per population. Observed (H-O) heterozygosity ranged from 0.12-0.65 per locus within populations; but, in 13 of 36 tests, H-O was less than expected. Despite low levels of allelic diversity, genetic structure estimated as theta was significant for all pairwise comparisons between populations (theta = 0.05-0.23). Due to suspected null alleles at four loci, ENA (excluding null alleles) corrected F-ST estimates …

Genetic Tests Of The Isolation Of Rare Coastal Dwarf Populations Of Banksia Spinulosa, Eleanor K. O'Brien, Lucia A. Aguilar, David J. Ayre, Robert J. Whelan

Faculty of Science - Papers (Archive)

In southern New South Wales, a suite of widespread plant species exhibit short-statured 'dwarf' growth forms on coastal headlands. It is unclear whether such populations are genetically distinct or whether dwarfism is a plastic response to the environment. We used four microsatellite markers to assess genetic differentiation among populations from coastal and inland sites for Banksia spinulosa var. spinulosa. We sampled plants from six locations, including from three 'dwarf' and three 'normal' populations. Mean levels of genetic diversity were slightly higher in the forest (Na≤7. 07±0.25; He≤0.80±0.09) than on the coast (N a≤5.92±0.70; He≤0.72±0.10). In general, populations displayed genotypic diversity …

Copy Number Variation Shapes Genome Diversity In Arabidopsis Over Immediate Family Generational Scales, Seth Debolt

Horticulture Faculty Publications

Arabidopsis thaliana is the model plant and is grown worldwide by plant biologists seeking to dissect the molecular underpinning of plant growth and development. Gene copy number variation (CNV) is a common form of genome natural diversity that is currently poorly studied in plants and may have broad implications for model organism research, evolutionary biology, and crop science. Herein, comparative genomic hybridization (CGH) was used to identify and interrogate regions of gene CNV across the A. thaliana genome. A common temperature condition used for growth of A. thaliana in our laboratory and many around the globe is 22 degrees C. …