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Biodistribution And Biopersistence Of Ceria Engineered Nanomaterials: Size Dependence, Robert A. Yokel, Michael T. Tseng, Mo Dan, Jason M. Unrine, Uschi M. Graham, Peng Wu, Eric A. Grulke

Pharmaceutical Sciences Faculty Publications

The aims were to determine the biodistribution, translocation, and persistence of nanoceria in the brain and selected peripheral organs. Nanoceria is being studied as an anti-oxidant therapeutic. Five, 15, 30, or 55 nm ceria was iv infused into rats which were terminated 1, 20, or 720 h later. Cerium was determined in blood, brain, liver, and spleen. Liver and spleen contained a large percentage of the dose, from which there was no significant clearance over 720 h, associated with adverse changes. Very little nanoceria entered brain parenchyma. The results suggest brain delivery of nanoceria will be a challenge.

FROM THE …

Competition For Antigen At The Level Of The Apc Is A Major Determinant Of Immunodominance During Memory Inflation In Murine Cytomegalovirus Infection., Lila A Farrington, Tameka A Smith, Finn Grey, Ann B Hill, Christopher M. Snyder

Department of Microbiology and Immunology Faculty Papers

The unique ability of CMV to drive the expansion of virus-specific T cell populations during the course of a lifelong, persistent infection has generated interest in the virus as a potential vaccine strategy. When designing CMV-based vaccine vectors to direct immune responses against HIV or tumor Ags, it becomes important to understand how and why certain CMV-specific populations are chosen to inflate over time. To investigate this, we designed recombinant murine CMVs (MCMVs) encoding a SIINFEKL-enhanced GFP fusion protein under the control of endogenous immediate early promoters. When mice were infected with these viruses, T cells specific for the SIINFEKL …

Neuroinflammation And Psychiatric Illness, Souhel Najjar, Daniel M. Pearlman, Kenneth Alper, Amanda Najjar, Orrin Devinsky

Dartmouth Scholarship

Multiple lines of evidence support the pathogenic role of neuroinflammation in psychiatric illness. While systemic autoimmune diseases are well-documented causes of neuropsychiatric disorders, synaptic autoimmune encephalitides with psychotic symptoms often go under-recognized. Parallel to the link between psychiatric symptoms and autoimmunity in autoimmune diseases, neuroimmunological abnormalities occur in classical psychiatric disorders (for example, major depressive, bipolar, schizophrenia, and obsessive-compulsive disorders). Investigations into the pathophysiology of these conditions traditionally stressed dysregulation of the glutamatergic and monoaminergic systems, but the mechanisms causing these neurotransmitter abnormalities remained elusive. We review the link between autoimmunity and neuropsychiatric disorders, and the human and experimental evidence …

The Eagleville Times,Volume 11, Issue 4, Debbie Ryan

Eagleville Times

No abstract provided.

Intra-Tumoral Heterogeneity In Metastatic Potential And Survival Signaling Between Iso-Clonal Hct116 And Hct116b Human Colon Carcinoma Cell Lines., Sanjib Chowdhury, Melanie Ongchin, Elizabeth Sharratt, Ivan Dominguez, J. Wang, Michael G. Brattain, Ashwani Rajput

Journal Articles: Eppley Institute

BACKGROUND: Colorectal cancer (CRC) metastasis is a leading cause of cancer-related deaths in the United States. The molecular mechanisms underlying this complex, multi-step pathway are yet to be completely elucidated. Recent reports have stressed the importance of intra-tumoral heterogeneity in the development of a metastatic phenotype. The purpose of this study was to characterize the intra-tumoral phenotypic heterogeneity between two iso-clonal human colon cancer sublines HCT116 and HCT116b on their ability to undergo metastatic colonization and survive under growth factor deprivation stress (GFDS).

MATERIALS AND METHODS: HCT116 and HCT116b cells were transfected with green fluorescence protein and subcutaneously injected into …

Pick1 And Ica69 Control Insulin Granule Trafficking And Their Deficiencies Lead To Impaired Glucose Tolerance, Mian Cao, Zhuo Mao, Chuen Kam, Nan (Tori) Xiao, Xiaoxing Cao, Chong Shen, Kenneth K. Y. Cheng, Aimin Xu, Kwong-Man Lee, Liwen Jiang, Jun Xia

All Dugoni School of Dentistry Faculty Articles

Diabetes is a metabolic disorder characterized by hyperglycemia. Insulin, which is secreted by pancreatic beta cells, is recognized as the critical regulator of blood glucose, but the molecular machinery responsible for insulin trafficking remains poorly defined. In particular, the roles of cytosolic factors that govern the formation and maturation of insulin granules are unclear. Here we report that PICK1 and ICA69, two cytosolic lipid-binding proteins, formed heteromeric BAR-domain complexes that associated with insulin granules at different stages of their maturation. PICK1-ICA69 heteromeric complexes associated with immature secretory granules near the trans-Golgi network (TGN). A brief treatment of Brefeldin A, which …

Neither Sad Nor Strange: Recovering The Logic Of Anticruelty Organizations In Gilded Age America, Bryn Resser Pallesen

Michigan Law Review

In 1877, the American Humane Association ("AHA") incorporated as one of the first national organizations dedicated to the protection of animals. Nine years later, it amended its constitution to include the protection of children in its chartered mission. By 1908, there were 354 anticruelty organizations in the United States, 185 of which were, like the AHA, humane societies invested in the welfare of both animals and children (pp. 2-3). As primary source documents reveal, Gilded Age humanitarians viewed the joint pursuit of child and animal protection as entirely sensible (p. 5). One of the Illinois Humane Society's founding directors, for …

Humans And Dolphins: An Exploration Of Anthropocentrism In Applied Environmental Ethics, Thomas I. White

Management Faculty Works

This article argues that one of the reasons that the unethical character of much human-dolphin contact is not more apparent to ethicists is that discussion of central issues has been colored with unintentional species bias. This article points out weaknesses in the traditional approach to discussing topics that bear on the question of whether dolphins have moral standing. It demonstrates that discussions of the cognitive abilities of dolphins by Steven Wise and Alasdair MacIntyre are unintentionally but fundamentally anthropocentric-largely because the authors are not familiar with enough of the scientific literature about dolphins to draw the conclusions that they do.

Intracranial Injection Of Aav Expressing Nep But Not Ide Reduces Amyloid Pathology In App+Ps1 Transgenic Mice, Nikisha Carty, Kevin R. Nash, Milene Brownlow, Dana Cruite, Donna M. Wilcock, Maj-Linda B. Selenica, Daniel C. Lee, Marcia N. Gordon, Dave Morgan

Sanders-Brown Center on Aging Faculty Publications

The accumulation of β-amyloid peptides in the brain has been recognized as an essential factor in Alzheimer's disease pathology. Several proteases, including Neprilysin (NEP), endothelin converting enzyme (ECE), and insulin degrading enzyme (IDE), have been shown to cleave β-amyloid peptides (Aβ). We have previously reported reductions in amyloid in APP+PS1 mice with increased expression of ECE. In this study we compared the vector-induced increased expression of NEP and IDE. We used recombinant adeno-associated viral vectors expressing either native forms of NEP (NEP-n) or IDE (IDE-n), or engineered secreted forms of NEP (NEP-s) or IDE (IDE-s). In a six-week study, immunohistochemistry …

Derivation Of Multivariate Syndromic Outcome Metrics For Consistent Testing Across Multiple Models Of Cervical Spinal Cord Injury In Rats, Adam R. Ferguson, Karen-Amanda Irvine, John C. Gensel, Jessica L. Nielson, Amity Lin, Johnathan Ly, Mark R. Segal, Rajiv R. Ratan, Jacqueline C. Bresnahan, Michael S. Beattie

Physiology Faculty Publications

Spinal cord injury (SCI) and other neurological disorders involve complex biological and functional changes. Well-characterized preclinical models provide a powerful tool for understanding mechanisms of disease; however managing information produced by experimental models represents a significant challenge for translating findings across research projects and presents a substantial hurdle for translation of novel therapies to humans. In the present work we demonstrate a novel 'syndromic' information-processing approach for capitalizing on heterogeneous data from diverse preclinical models of SCI to discover translational outcomes for therapeutic testing. We first built a large, detailed repository of preclinical outcome data from 10 years of basic …

Westray, Wilbur Morgan, Sr., 1921-2000 (Sc 965), Manuscripts & Folklife Archives

Manuscript Collection Finding Aids

Finding aid and scans (Click on "Additional Files" below) for Manuscripts Small Collection 965. Paper (22 p.) titled “My Early Life [,] 1921-1939” written by Wilbur Morgan Westray, Sr. Westray recounts life as he experienced it growing up in Louisville, Kentucky. Also includes associated genealogical data.

Flagellar Motility Is A Key Determinant Of The Magnitude Of The Inflammasome Response To Pseudomonas Aeruginosa, Yash R. Patankar, Rustin R. Lovewell, Matthew E. Poynter, Jeevan Jyot, Barbara I. Kazmierczak, Brent Berwin

Dartmouth Scholarship

We previously demonstrated that bacterial flagellar motility is a fundamental mechanism by which host phagocytes bind and ingest bacteria. Correspondingly, loss of bacterial motility, consistently observed in clinical isolates from chronic Pseudomonas aeruginosa infections, enables bacteria to evade association and ingestion of P. aeruginosa by phagocytes both in vitro and in vivo. Since bacterial interactions with the phagocyte cell surface are required for type three secretion system-dependent NLRC4 inflammasome activation by P. aeruginosa, we hypothesized that reduced bacterial association with phagocytes due to loss of bacterial motility, independent of flagellar expression, will lead to reduced inflammasome activation. Here we report …

Multi-Allelic Major Effect Genes Interact With Minor Effect Qtls To Control Adaptive Color Pattern Variation In Heliconius Erato., Riccardo Papa, Durrell D. Kapan, Brian A. Counterman, Karla Maldonado, Daniel P. Lindstrom, Robert D. Reed, H. Frederik Nijhout, Tomas Hrbek, W. Owen Mcmillan

CAS Publications

Recent studies indicate that relatively few genomic regions are repeatedly involved in the evolution of Heliconius butterfly wing patterns. Although this work demonstrates a number of cases where homologous loci underlie both convergent and divergent wing pattern change among different Heliconius species, it is still unclear exactly how many loci underlie pattern variation across the genus. To address this question for Heliconius erato, we created fifteen independent crosses utilizing the four most distinct color pattern races and analyzed color pattern segregation across a total of 1271 F2 and backcross offspring. Additionally, we used the most variable brood, an F2 cross …

Corpse Management In Social Insects, Qian Sun, Xuguo Zhou

Entomology Faculty Publications

Undertaking behavior is an essential adaptation to social life that is critical for colony hygiene in enclosed nests. Social insects dispose of dead individuals in various fashions to prevent further contact between corpses and living members in a colony. Focusing on three groups of eusocial insects (bees, ants, and termites) in two phylogenetically distant orders (Hymenoptera and Isoptera), we review mechanisms of death recognition, convergent and divergent behavioral responses toward dead individuals, and undertaking task allocation from the perspective of division of labor. Distinctly different solutions (e.g., corpse removal, burial and cannibalism) have evolved, independently, in the holometabolous hymenopterans and …

Cd4 And Cd8 T Cells Directly Recognize Murine Gammaherpesvirus 68-Immortalized Cells And Prevent Tumor Outgrowth, Xiaozhan Liang, Rebecca L. Crepeau, Weijun Zhang, Samuel H. Speck, Edward J. Usherwood

Dartmouth Scholarship

There has been extensive research regarding T cell recognition of Epstein-Barr virus-transformed cells; however, less is known regarding the recognition of B cells immortalized by gamma-2 herpesviruses. Here we show that B cells immortalized by murine gammaherpesvirus 68 (MHV-68, γHV-68) can be controlled by either CD4 or CD8 T cells in vivo. We present evidence for the direct recognition of infected B cells by CD4 and CD8 T cells. These data will help in the development of immunotherapeutic approaches combating gamma-2 herpesvirus-related disease.

Loss Of Fbp1 By Snail-Mediated Repression Provides Metabolic Advantages In Basal-Like Breast Cancer, Chenfang Dong, Tingting Yuan, Yadi Wu, Yifan Wang, Teresa W-M Fan, Sumitra Miriyala, Yiwei Lin, Jun Yao, Jian Shi, Tiebang Kang, Pawel Lorkiewicz, Daret St. Clair, Mien-Chie Hung, B. Mark Evers, Binhua P. Zhou

Toxicology and Cancer Biology Faculty Publications

The epithelial-mesenchymal transition (EMT) enhances cancer invasiveness and confers tumor cells with cancer stem cell (CSC)-like characteristics. We show that the Snail-G9a-Dnmt1 complex, which is critical for E-cadherin promoter silencing, is also required for the promoter methylation of fructose-1,6-biphosphatase (FBP1) in basal-like breast cancer (BLBC). Loss of FBP1 induces glycolysis and results in increased glucose uptake, macromolecule biosynthesis, formation of tetrameric PKM2, and maintenance of ATP production under hypoxia. Loss of FBP1 also inhibits oxygen consumption and reactive oxygen species production by suppressing mitochondrial complex I activity; this metabolic reprogramming results in an increased CSC-like property and tumorigenicity by enhancing …

Calpain 1 Knockdown Improves Tissue Sparing And Functional Outcomes After Spinal Cord Injury In Rats, Chen Guang Yu, Yanzhang Li, Kashif Raza, Xin Xin Yu, Sarbani Ghoshal, James W. Geddes

Spinal Cord and Brain Injury Research Center Faculty Publications

To evaluate the hypothesis that calpain 1 knockdown would reduce pathological damage and functional deficits after spinal cord injury (SCI), we developed lentiviral vectors encoding calpain 1 shRNA and eGFP as a reporter (LV-CAPN1 shRNA). The ability of LV-CAPN1 shRNA to knockdown calpain 1 was confirmed in rat NRK cells using Northern and Western blot analysis. To investigate the effects on spinal cord injury, LV-CAPN1shRNA or LV-mismatch control shRNA (LV-control shRNA) were administered by convection enhanced diffusion at spinal cord level T10 in Long-Evans female rats (200–250 g) 1 week before contusion SCI, 180 kdyn force, or sham surgery at …

Lymphotoxin-Α Is A Novel Adiponectin Expression Suppressor Following Myocardial Ischemia/Reperfusion., Wayne Bond Lau, Yanqing Zhang, Jianli Zhao, Baojiang Liu, Xiaoliang Wang, Yuexing Yuan, Theodore A. Christopher, Bernard Lopez, Erhe Gao, Walter J. Koch, Xin L. Ma, Yajing Wang

Department of Emergency Medicine Faculty Papers

Recent clinical observations demonstrate adiponectin (APN), an adipocytokine with potent cardioprotective actions, is significantly reduced following myocardial ischemia/reperfusion (MI/R). However, mechanisms responsible for MI/R-induced hypoadiponectinemia remain incompletely understood. Adult male mice were subjected to 30-min MI followed by varying reperfusion periods. Adipocyte APN mRNA and protein expression and plasma APN and TNFα concentrations were determined. APN expression/production began to decline 3 h after reperfusion (reaching nadir 12 h after reperfusion), returning to control levels 7 days after reperfusion. Plasma TNFα levels began to increase 1 h after reperfusion, peaking at 3 h and returning to control levels 24 h after …

Integrated Analysis Of Cytochrome P450 Gene Superfamily In The Red Flour Beetle, Tribolium Castaneum, Fang Zhu, Timothy W. Moural, Kapil Shah, Subba Reddy Palli

Entomology Faculty Publications

BACKGROUND: The functional and evolutionary diversification of insect cytochrome P450s (CYPs) shaped the success of insects. CYPs constitute one of the largest and oldest gene superfamilies that are found in virtually all aerobic organisms. Because of the availability of whole genome sequence and well functioning RNA interference (RNAi), the red flour beetle, Tribolium castaneum serves as an ideal insect model for conducting functional genomics studies. Although several T. castaneum CYPs had been functionally investigated in our previous studies, the roles of the majority of CYPs remain largely unknown. Here, we comprehensively analyzed the phylogenetic relationship of all T. castaneum CYPs …

Experimental And Natural Warming Elevates Mercury Concentrations In Estuarine Fish, Jennifer A. Dijkstra, Kate L. Buckman, Darren Ward, David W. Evans, Michele Dionne, Celia Y. Chen

Dartmouth Scholarship

Marine food webs are the most important link between the global contaminant, methylmercury (MeHg), and human exposure through consumption of seafood. Warming temperatures may increase human exposure to MeHg, a potent neurotoxin, by increasing MeHg production as well as bioaccumulation and trophic transfer through marine food webs. Studies of the effects of temperature on MeHg bioaccumulation are rare and no study has specifically related temperature to MeHg fate by linking laboratory experiments with natural field manipulations in coastal ecosystems. We performed laboratory and field experiments on MeHg accumulation under varying temperature regimes using the killifish, Fundulus heteroclitus. Temperature treatments …

Nanosecond Pulsed Electric Field Thresholds For Nanopore Formation In Neural Cells., Caleb C Roth, Gleb P Tolstykh, Jason A Payne, Marjorie A Kuipers, Gary L. Thompson Iii, Mauris N Desilva, Bennett L Ibey

Henry M. Rowan College of Engineering Departmental Research

The persistent influx of ions through nanopores created upon cellular exposure to nanosecond pulse electric fields (nsPEF) could be used to modulate neuronal function. One ion, calcium (Ca(2+)), is important to action potential firing and regulates many ion channels. However, uncontrolled hyper-excitability of neurons leads to Ca(2+) overload and neurodegeneration. Thus, to prevent unintended consequences of nsPEF-induced neural stimulation, knowledge of optimum exposure parameters is required. We determined the relationship between nsPEF exposure parameters (pulse width and amplitude) and nanopore formation in two cell types: rodent neuroblastoma (NG108) and mouse primary hippocampal neurons (PHN). We identified thresholds for nanoporation using …

Ontogenetic Variation In Cold Tolerance Plasticity In Drosophila: Is The Bogert Effect Bogus?, Katherine A Mitchell, Brent J Sinclair, John S Terblanche

Biology Publications

Ontogenetic variation in plasticity is important to understanding mechanisms and patterns of thermal tolerance variation. The Bogert effect postulates that, to compensate for their inability to behaviourally thermoregulate, less-mobile life stages of ectotherms are expected to show greater plasticity of thermal tolerance than more-mobile life stages. We test this general prediction by comparing plasticity of thermal tolerance (rapid cold-hardening, RCH) between mobile adults and less-mobile larvae of 16 Drosophila species. We find an RCH response in adults of 13 species but only in larvae of four species. Thus, the Bogert effect is not as widespread as expected.

Identification Of Cold-Responsive Genes In A New Zealand Alpine Stick Insect Using Rna-Seq., Luke T Dunning, Alice B Dennis, Duckchul Park, Brent J Sinclair, Richard D Newcomb, Thomas R Buckley

Biology Publications

The endemic New Zealand alpine stick insect Micrarchus nov. sp. 2 regularly experiences sub-zero temperatures in the wild. 454-based RNA-Seq was used to generate a de novo transcriptome and differentiate between treatments to investigate the genetic basis of cold tolerance. Non cold-treated individuals were compared to those exposed to 0°C for 1 h followed by a 1 h recovery period at 20°C. We aligned 607,410 Roche 454 reads, generating a transcriptome of 5235 contigs. Differential expression analysis ranked candidate cold responsive genes for qPCR validation by P-value. The top nine up-regulated candidates, together with eight a priori targets identified from …

Effects Of Aging On Apoptosis Gene Expression In Oral Mucosal Tissues, Octavio A. Gonzalez, Michael John Novak, Sreenatha S. Kirakodu, Arnold J. Stromberg, Shu Shen, Luis Orraca, Janis Gonzalez-Martinez, Jeffrey L. Ebersole

Center for Oral Health Research Faculty Publications

Apoptotic processes are important for physiologic renewal of an intact epithelial barrier and contribute some antimicrobial resistance for bacteria and viruses, as well as anti-inflammatory effects that benefits the mucosa. The oral cavity presents a model of host-bacterial interactions at mucosal surfaces, in which a panoply of microorganisms colonizes various niches in the oral cavity and creates complex multispecies biofilms that challenge the gingival tissues. This report details gene expression in apoptotic pathways that occur in oral mucosal tissues across the lifespan, using a nonhuman primate model. Macaca mulatta primates from 2 to 23 years of age (n = …

The Eagleville Times,Volume 11, Issue 3, Debbie Ryan

Eagleville Times

No abstract provided.

Population Impacts Of Wolbachia On Aedes Albopictus, James W. Mains, Corey L. Brelsfoard, Philip R. Crain, Yunxin Huang, Stephen L. Dobson

Entomology Faculty Publications

Prior studies have demonstrated that Wolbachia, a commonly occurring bacterium capable of manipulating host reproduction, can affect life history traits in insect hosts, which in turn can have population-level effects. Effects on hosts at the individual level are predicted to impact population dynamics, but the latter has not been examined empirically. Here, we describe a biological model system based on Aedes albopictus (Asian tiger mosquito) that allows for measurement of population dynamics, which has not been accomplished in prior field trials or laboratory designs. The results demonstrate the studied populations to be robust and allow for persistent, closed populations with …

Melanopsin, Photosensitive Ganglion Cells, And Seasonal Affective Disorder., Kathryn A Roecklein, Patricia M Wong, Megan A Miller, Shannon D Donofry, Marissa L Kamarck, George C Brainard

Department of Neurology Faculty Papers

In two recent reports, melanopsin gene variations were associated with seasonal affective disorder (SAD), and in changes in the timing of sleep and activity in healthy individuals. New studies have deepened our understanding of the retinohypothalamic tract, which translates environmental light received by the retina into neural signals sent to a set of nonvisual nuclei in the brain that are responsible for functions other than sight including circadian, neuroendocrine and neurobehavioral regulation. Because this pathway mediates seasonal changes in physiology, behavior, and mood, individual variations in the pathway may explain why approximately 1-2% of the North American population develops mood …

Mir203 Mediates Subversion Of Stem Cell Properties During Mammary Epithelial Differentiation Via Repression Of Δnp63Α And Promotes Mesenchymal-To-Epithelial Transition, A J. Decastro, K A. Dunphy, J Hutchinson, A L. Balboni, P Cherukuri, D J. Jerry, J Direnzo

Dartmouth Scholarship

During reproductive life, the mammary epithelium undergoes consecutive cycles of proliferation, differentiation and apoptosis. Doing so relies on the retained proliferative capacity, prolonged lifespan and developmental potency of mammary stem cells (MaSCs). ΔNp63α, the predominant TP63 isoform in mammary epithelia, is robustly expressed in MaSCs and is required for preservation of self-renewing capacity in diverse epithelial structures. However, the mechanism(s) underlying subversion of this activity during forfeiture of self-renewing capacity are poorly understood. MicroRNAs (miRNAs) govern critical cellular functions including stem cell maintenance, development, cell cycle regulation and differentiation by disrupting translation of target mRNAs. Data presented here …

An Acacb Variant Implicated In Diabetic Nephropathy Associates With Body Mass Index And Gene Expression In Obese Subjects, Lijun Ma, Mariana Murea, James A. Snipes, Alejandra Marinelarena, Jacqueline Krüger, Pamela J. Hicks, Kurt A. Langberg, Meredith A. Bostrom, Jessica N. Cooke, Daisuke Suzuki, Tetsuya Babazono, Takashi Uzu, Sydney C. W. Tang, Ashis K. Mondal, Neeraj K. Sharma, Sayuko Kobes, Peter A. Antinozzi, Matthew Davis, Swapan K. Das, Neda Rasouli, Philip A. Kern, Nathan J. Shores, Lawrence L. Rudel, Matthias Blüher, Michael Stumvoll, Donald W. Bowden, Shiro Maeda, John S. Parks, Peter Kovacs, Robert L. Hanson, Leslie J. Baier, Steven C. Elbein, Barry I. Freedman

Internal Medicine Faculty Publications

Acetyl coenzyme A carboxylase B gene (ACACB) single nucleotide polymorphism (SNP) rs2268388 is reproducibly associated with type 2 diabetes (T2DM)-associated nephropathy (DN). ACACB knock-out mice are also protected from obesity. This study assessed relationships between rs2268388, body mass index (BMI) and gene expression in multiple populations, with and without T2DM. Among subjects without T2DM, rs2268388 DN risk allele (T) associated with higher BMI in Pima Indian children (n = 2021; p-additive = 0.029) and African Americans (AAs) (n = 177; p-additive = 0.05), with a trend in European Americans (EAs) (n = 512; p-additive = 0.09), but not Germans (n …

Role Of An Iron-Dependent Transcriptional Regulator In The Pathogenesis And Host Response To Infection With Streptococcus Pneumoniae., Radha Gupta, Minny Bhatty, Edwin Swiatlo, Bindu Nanduri

CVM Publications

Iron is a critical cofactor for many enzymes and is known to regulate gene expression in many bacterial pathogens. Streptococcus pneumoniae normally inhabits the upper respiratory mucosa but can also invade and replicate in lungs and blood. These anatomic sites vary considerably in both the quantity and form of available iron. The genome of serotype 4 pneumococcal strain TIGR4 encodes a putative iron-dependent transcriptional regulator (IDTR). A mutant deleted at idtr (?idtr) exhibited growth kinetics similar to parent strain TIGR4 in vitro and in mouse blood for up to 48 hours following infection. However, ?idtr was significantly attenuated in a …