Life Sciences Commons^™

The Gut Of Geographically Disparate Ciona Intestinalis Harbors A Core Microbiota, Larry J. Dishaw, Jaime Flores-Torres, Simon Lax, Kristina Gemayel, Brittany Leigh, Daniela Melillo, M. Gail Mueller, Lenina Natale, Ivana Zucchetti, Rosaria De Santis, Maria Rosaria Pinto, Gary W. Litman, Jack W. Gilbert

Marine Science Faculty Publications

It is now widely understood that all animals engage in complex interactions with bacteria (or microbes) throughout their various life stages. This ancient exchange can involve cooperation and has resulted in a wide range of evolved host-microbial interdependencies, including those observed in the gut. Ciona intestinalis, a filter-feeding basal chordate and classic developmental model that can be experimentally manipulated, is being employed to help define these relationships. Ciona larvae are first exposed internally to microbes upon the initiation of feeding in metamorphosed individuals; however, whether or not these microbes subsequently colonize the gut and whether or not Ciona forms …

Sexual Dimorphism Of Staminate- And Pistillate-Phase Flowers Of Saponaria Officinalis (Bouncing Bet) Affects Pollinator Behavior And Seed Set, Sandra L. Davis, Dana A. Dudle, Jenna R. Nawrocki, Leah M. Freestone, Peter Konieczny, Michael B. Tobin, Michael M. Britton

Biology Faculty publications

The sequential separation of male and female function in flowers of dichogamous species allows for the evolution of differing morphologies that maximize fitness through seed siring and seed set. We examined staminate- and pistillate-phase flowers of protandrous Saponaria officinalis for dimorphism in floral traits and their effects on pollinator attraction and seed set. Pistillate-phase flowers have larger petals, greater mass, and are pinker in color, but due to a shape change, pistillate-phase flowers have smaller corolla diameters than staminate-phase flowers. There was no difference in nectar volume or sugar content one day after anthesis, and minimal evidence for UV nectar …

Integrated Assessment Of Predicted Mhc Binding And Cross-Conservation With Self Reveals Patterns Of Viral Camouflage, Lu He, Anne S. De Groot, Andres H. Gutierrez, William D. Martin, Lenny Moise, Chris Bailey-Kellogg

Dartmouth Scholarship

Immune recognition of foreign proteins by T cells hinges on the formation of a ternary complex sandwiching a constituent peptide of the protein between a major histocompatibility complex (MHC) molecule and a T cell receptor (TCR). Viruses have evolved means of "camouflaging" themselves, avoiding immune recognition by reducing the MHC and/or TCR binding of their constituent peptides. Computer-driven T cell epitope mapping tools have been used to evaluate the degree to which articular viruses have used this means of avoiding immune response, but most such analyses focus on MHC-facing ‘agretopes'. Here we set out a new means of evaluating the …

The Wnt/Planar Cell Polarity Pathway Component Vangl2 Induces Synapse Formation Through Direct Control Of N-Cadherin, Tadahiro Nagaoka, Riuko Ohashi, Ayumu Inutsuka, Seiko Sakai, Nobuyoshi Fujisawa, Minesuke Yokoyama, Yina H. Huang, Michihiro Igarashi, Masashi Kishi

Dartmouth Scholarship

Although regulators of the Wnt/planar cell polarity (PCP) pathway are widely expressed in vertebrate nervous systems, their roles at synapses are unknown. Here, we show that Vangl2 is a postsynaptic factor crucial for synaptogenesis and that it coprecipitates with N-cadherin and PSD-95 from synapse-rich brain extracts. Vangl2 directly binds N-cadherin and enhances its internalization in a Rab5-dependent manner. This physical and functional interaction is suppressed by β-catenin, which binds the same intracellular region of N-cadherin as Vangl2. In hippocampal neurons expressing reduced Vangl2 levels, dendritic spine formation as well as synaptic marker clustering is significantly impaired. Furthermore, Prickle2, another postsynaptic …

Quantitative Field Testing Heterodera Glycines From Metagenomic Dna Samples Isolated Directly From Soil Under Agronomic Production., Yan Li, Gary W. Lawrence, Shien Lu, Clarissa Balbalian, Vincent P. Klink

CALS Publications

A quantitative PCR procedure targeting the Heterodera glycines ortholog of the Caenorhabditis elegans uncoordinated-78 gene was developed. The procedure estimated the quantity of H. glycines from metagenomic DNA samples isolated directly from field soil under agronomic production. The estimation of H. glycines quantity was determined in soil samples having other soil dwelling plant parasitic nematodes including Hoplolaimus, predatory nematodes including Mononchus, free-living nematodes and biomass. The methodology provides a framework for molecular diagnostics of nematodes from metagenomic DNA isolated directly from field soil.

Primate Energy Eexpenditure And Life History, Herman Pontzer, David A. Raichlen, Adam D. Gordon, Kara K. Schroepfer-Walker, Brian Hare, Matthew C. O’Neill, Kathleen M. Muldoon

Dartmouth Scholarship

Humans and other primates are distinct among placental mammals in having exceptionally slow rates of growth, reproduction, and aging. Primates’ slow life history schedules are generally thought to reflect an evolved strategy of allocating energy away from growth and reproduction and toward somatic investment, particularly to the development and maintenance of large brains. Here we examine an alternative explanation: that primates’ slow life histories reflect low total energy expenditure (TEE) (kilocalories per day) relative to other placental mammals. We compared doubly labeled water measurements of TEE among 17 primate species with similar measures for other placental mammals. We found that …

Magnitude Of The Freshwater Turtle Exports From The Us: Long Term Trends And Early Effects Of Newly Implemented Harvest Management Regimes., Ivana Mali, Michael W. Vandewege, Scott K. Davis, Michael R.J. Forstner

CALS Publications

Unregulated commercial harvest remains a major threat for turtles across the globe. Due to continuing demand from Asian markets, a significant number of turtles are exported from the United States of America (US). Beginning in 2007, several southeastern states in the US implemented restrictions on the commercial harvest of turtles, in order to address the unsustainable take. We have summarized freshwater turtle exports from the US between 2002 and 2012 and demonstrated that the magnitude of turtle exports from the US remained high although the exports decreased throughout the decade. Louisiana and California were the major exporters. The majority of …

Rna Viral Metagenome Of Whiteflies Leads To The Discovery And Characterization Of A Whitefly-Transmitted Carlavirus In North America, Karyna Rosario, Heather Capobianco, Terry Fei Fan Ng, Mya Breitbart, Jane E. Polston

Marine Science Faculty Publications

Whiteflies from the Bemisia tabaci species complex have the ability to transmit a large number of plant viruses and are some of the most detrimental pests in agriculture. Although whiteflies are known to transmit both DNA and RNA viruses, most of the diversity has been recorded for the former, specifically for the Begomovirus genus. This study investigated the total diversity of DNA and RNA viruses found in whiteflies collected from a single site in Florida to evaluate if there are additional, previously undetected viral types within the B. tabaci vector. Metagenomic analysis of viral DNA extracted from the whiteflies only …

An Imaging-Based Platform For High-Content, Quantitative Evaluation Of Therapeutic Response In 3d Tumour Models, Jonathan P. Celli, Imran Rizvi, Adam R. Blanden, Iqbal Massodi, Iqbal Massodi, Michael D. Glidden, Brian Pogue, Tayyaba Hasan

Dartmouth Scholarship

While it is increasingly recognized that three-dimensional (3D) cell culture models recapitulate drug responses of human cancers with more fidelity than monolayer cultures, a lack of quantitative analysis methods limit their implementation for reliable and routine assessment of emerging therapies. Here, we introduce an approach based on computational analysis of fluorescence image data to provide high-content readouts of dose-dependent cytotoxicity, growth inhibition, treatment-induced architectural changes and size-dependent response in 3D tumour models. We demonstrate this approach in adherent 3D ovarian and pancreatic multiwell extracellular matrix tumour overlays subjected to a panel of clinically relevant cytotoxic modalities and appropriately designed controls …

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 …

Redox-Dependent Stability, Protonation, And Reactivity Of Cysteine-Bound Heme Proteins, Fangfang Zhong, George P. Lisi, Daniel P. Collins, John H. Dawson, Ekaterina V. Pletneva

Dartmouth Scholarship

Cysteine-bound hemes are key components of many enzymes and biological sensors. Protonation (deprotonation) of the Cys ligand often accompanies redox transformations of these centers. To characterize these phenomena, we have engineered a series of Thr78Cys/Lys79Gly/Met80X mutants of yeast cytochrome c (cyt c) in which Cys78 becomes one of the axial ligands to the heme. At neutral pH, the protonation state of the coordinated Cys differs for the ferric and ferrous heme species, with Cys binding as a thiolate and a thiol, respectively. Analysis of redox-dependent stability and alkaline transitions of these model proteins, as well as comparisons to Cys …

Enzymatic Activity In The Chorion For Hatching In The California Grunion, Emily R. Pierce, Vince V. Quach, Karen L. Martin

Featured Research

Leuresthes tenuis is a small, silverside fish that spawns on the beaches during some of the highest tides of the summer months. Of the many unique traits to the species including that the eggs develop fully out of water to the point of hatching competence but will not hatch until presented with an environmental cue, which causes them to hatch in less than a minute. The purpose of this study is to better understand the role of enzymes called chorionases, which act to break down the chorion (egg membrane). I hypothesize that the chorion begins to weaken in this species …

Non-Invasive Mri And Spectroscopy Of Mdx Mice Reveal Temporal Changes In Dystrophic Muscle Imaging And In Energy Deficits., Christopher R. Heier, Alfredo D. Guerron, Alexandru Korotcov, Stephen Lin, Heather Gordish-Dressman, Stanley Fricke, Raymond W. Sze, Eric P. Hoffman, Paul Wang, Kanneboyina Nagaraju

Genomics and Precision Medicine Faculty Publications

In Duchenne muscular dystrophy (DMD), a genetic disruption of dystrophin protein expression results in repeated muscle injury and chronic inflammation. Magnetic resonance imaging shows promise as a surrogate outcome measure in both DMD and rehabilitation medicine that is capable of predicting clinical benefit years in advance of functional outcome measures. The mdx mouse reproduces the dystrophin deficiency that causes DMD and is routinely used for preclinical drug testing. There is a need to develop sensitive, non-invasive outcome measures in the mdx model that can be readily translatable to human clinical trials. Here we report the use of magnetic resonance imaging …

Dielectric Characterization Of Coastal Cartilage Chondrocytes, Michael W. Stacey, Ahmet C. Sabuncu, Ali Beskok

Bioelectrics Publications

BACKGROUND: Chondrocytes respond to biomechanical and bioelectrochemical stimuli by secreting appropriate extracellular matrix proteins that enable the tissue to withstand the large forces it experiences. Although biomechanical aspects of cartilage are well described, little is known of the bioelectrochemical responses. The focus of this study is to identify bioelectrical characteristics of human costal cartilage cells using dielectric spectroscopy.

METHODS: Dielectric spectroscopy allows non-invasive probing of biological cells. An in house computer program is developed to extract dielectric properties of human costal cartilage cells from raw cell suspension impedance data measured by a microfluidic device. The dielectric properties of chondrocytes are …

Habitat-Specific Density And Diet Of Rapidly Expanding Invasive Red Lionfish, Pterois Volitans,, Populations In The Northern Gulf Of Mexico, Kristen A. Dahl, William F. Patterson Iii

C-IMAGE Publications

Invasive Indo-Pacific red lionfish, Pterois volitans, were first reported in the northern Gulf of Mexico (nGOM) in summer 2010. To examine potential impacts on native reef fish communities, lionfish density and size distributions were estimated from fall 2010 to fall 2013 with a remotely operated vehicle at natural (n = 16) and artificial (n = 22) reef sites. Lionfish (n = 934) also were sampled via spearfishing to examine effects of habitat type, season, and fish size on their diet and trophic ecology. There was an exponential increase in lionfish density at both natural and artificial reefs over the study …

Benthic And Pelagic Pathways Of Methylmercury Bioaccumulation In Estuarine Food Webs Of The Northeast United States, Celia Y. Chen, Mark E. Borsuk, Deenie M. Bugge, Terill Hollweg

Dartmouth Scholarship

Methylmercury (MeHg) is a contaminant of global concern that bioaccumulates and bioamagnifies in marine food webs. Lower trophic level fauna are important conduits of MeHg from sediment and water to estuarine and coastal fish harvested for human consumption. However, the sources and pathways of MeHg to these coastal fisheries are poorly known particularly the potential for transfer of MeHg from the sediment to biotic compartments. Across a broad gradient of human land impacts, we analyzed MeHg concentrations in food webs at ten estuarine sites in the Northeast US (from the Hackensack Meadowlands, NJ to the Gulf of Maine). MeHg concentrations …

Inflammatory Cytokine Gene Expression In Mesenteric Adipose Tissue During Acute Experimental Colitis, William Conan Mustain, Marlene E. Starr, Joseph Daniel Valentino, Donald A. Cohen, Daiki Okamura, Chi Wang, B. Mark Evers, Hiroshi Saito

Markey Cancer Center Faculty Publications

BACKGROUND: Production of inflammatory cytokines by mesenteric adipose tissue (MAT) has been implicated in the pathogenesis of inflammatory bowel disease (IBD). Animal models of colitis have demonstrated inflammatory changes within MAT, but it is unclear if these changes occur in isolation or as part of a systemic adipose tissue response. It is also unknown what cell types are responsible for cytokine production within MAT. The present study was designed to determine whether cytokine production by MAT during experimental colitis is depot-specific, and also to identify the source of cytokine production within MAT.

METHODS: Experimental colitis was induced in 6-month-old C57BL/6 …

Sensitization Of Human Cancer Cells To Gemcitabine By The Chk1 Inhibitor Mk-8776: Cell Cycle Perturbation And Impact Of Administration Schedule In Vitro And In Vivo, Ryan Montano, Ruth Thompson, Injae Chung, Huagang Hou, Nadeem Khan, Alan Eastman

Dartmouth Scholarship

Chk1 inhibitors have emerged as promising anticancer therapeutic agents particularly when combined with antimetabolites such as gemcitabine, cytarabine or hydroxyurea. Here, we address the importance of appropriate drug scheduling when gemcitabine is combined with the Chk1 inhibitor MK-8776, and the mechanisms involved in the schedule dependence.

Enrichment And Training Improve Cognition In Rats With Cortical Malformations, Kyle R. Jenks, Marcella M. Lucas, Ben A. Duffy, Ashlee A. Robbins, Barjor Gimi, Jeremy M. Barry, Rod C. Scott

Dartmouth Scholarship

Children with malformations of cortical development (MCD) frequently have associated cognitive impairments which reduce quality of life. We hypothesized that cognitive deficits associated with MCD can be improved with environmental manipulation or additional training. The E17 methylazoxymethanol acetate (MAM) exposure model bears many anatomical hallmarks seen in human MCDs as well as similar behavioral and cognitive deficits. We divided control and MAM exposed Sprague-Dawley rats into enriched and non-enriched groups and tested performance in the Morris water maze. Another group similarly divided underwent sociability testing and also underwent Magnetic Resonance Imaging (MRI) scans pre and post enrichment. A third group …

Use Of Irf-3 And/Or Irf-7 Knockout Mice To Study Viral Pathogenesis: Lessons From A Murine Retrovirus-Induced Aids Model, Megan A. O'Connor, William R. Green

Dartmouth Scholarship

Interferon regulatory factor (IRF) regulation of the type I interferon response has not been extensively explored in murine retroviral infections. IRF-3(-/-) and select IRF-3/7(-/-) mice were resistant to LP-BM5-induced pathogenesis. However, further analyses strongly suggested that resistance could be attributed to strain 129-specific contamination of the known retrovirus resistance gene Fv1. Therefore, caution should be taken when interpreting phenotypes observed in these knockout mice, as strain 129-derived genetic polymorphisms may explain observed differences.

Analgesic Tolerance Of Opioid Agonists In Mutant Mu-Opioid Receptors Expressed In Sensory Neurons Following Intrathecal Plasmid Gene Delivery, Guangwen Li, Fei Ma, Yanping Gu, Li-Yen Mae Huang

Physiology Faculty Publications

Background: Phosphorylation sites in the C-terminus of mu-opioid receptors (MORs) are known to play critical roles in the receptor functions. Our understanding of their participation in opioid analgesia is mostly based on studies of opioid effects on mutant receptors expressed in in vitro preparations, including cell lines, isolated neurons and brain slices. The behavioral consequences of the mutation have not been fully explored due to the complexity in studies of mutant receptors in vivo. To facilitate the determination of the contribution of phosphorylation sites in MOR to opioid-induced analgesic behaviors, we expressed mutant and wild-type human MORs (hMORs) in sensory …

The Gating Charge Should Not Be Estimated By Fitting A Two-State Model To A Q-V Curve, Francisco Bezanilla, Carlos A. Villalba-Galea

School of Pharmacy Faculty Articles

The voltage dependence of charges in voltage-sensitive proteins, typically displayed as charge versus voltage (Q-V) curves, is often quantified by fitting it to a simple two-state Boltzmann function. This procedure overlooks the fact that the fitted parameters, including the total charge, may be incorrect if the charge is moving in multiple steps. We present here the derivation of a general formulation for Q-V curves from multistate sequential models, including the case of infinite number of states. We demonstrate that the commonly used method to estimate the charge per molecule using a simple Boltzmann fit is not only inadequate, but in …

Fearless: Melissa Rich, Kathryn E. Bucolo

SURGE

Consistently striving to take what she learns in the classroom and apply it to her life, whether in terms of her interest in Native American issues or her passion for animals and desire to go to veterinary school, Melissa Rich ’14 serves her community humbly, respectfully, and with the intent to educate those around her. [excerpt]

Molecular Cloning And Characterization Of A P-Glycoprotein From The Diamondback Moth, Plutella Xylostella (Lepidoptera: Plutellidae), Lixia Tian, Jiaqiang Yang, Wenjie Hou, Baoyun Xu, Wen Xie, Shaoli Wang, Youjun Zhang, Xuguo Zhou, Qingjun Wu

Entomology Faculty Publications

Macrocyclic lactones such as abamectin and ivermectin constitute an important class of broad-spectrum insecticides. Widespread resistance to synthetic insecticides, including abamectin and ivermectin, poses a serious threat to the management of diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), a major pest of cruciferous plants worldwide. P-glycoprotein (Pgp), a member of the ABC transporter superfamily, plays a crucial role in the removal of amphiphilic xenobiotics, suggesting a mechanism for drug resistance in target organisms. In this study, PxPgp1, a putative Pgp gene from P. xylostella, was cloned and characterized. The open reading frame (ORF) of PxPgp1 consists of 3774 …

Short Duration Waveforms Recorded Extracellularly From Freely Moving Rats Are Representative Of Axonal Activity, Ashlee A. Robbins, Steven E. Fox, Gregory L. Holmes, Rod C. Scott, Jeremy M. Barry

Dartmouth Scholarship

While extracellular somatic action potentials from freely moving rats have been well characterized, axonal activity has not. We report direct extracellular tetrode recordings of putative axons whose principal feature is a short duration waveform (SDW) with an average peak-trough length less than 179 μs. While SDW recordings using tetrodes have previously been treated as questionable or classified as cells, we hypothesize that they are representative of axonal activity. These waveforms have significantly shorter duration than somatic action potentials, are triphasic and are therefore similar to classic descriptions of microelectrode recordings in white matter and of in vitro action potential propagation …

Evidence For Finely-Regulated Asynchronous Growth Of Toxoplasma Gondii Cysts Based On Data-Driven Model Selection, Adam M. Sullivan, Xiaopeng Zhao, Yasuhiro Suzuki, Eri Ochiai, Stephen Crutcher, Michael A. Gilchrist

Microbiology, Immunology, and Molecular Genetics Faculty Publications

Toxoplasma gondii establishes a chronic infection by forming cysts preferentially in the brain. This chronic infection is one of the most common parasitic infections in humans and can be reactivated to develop life-threatening toxoplasmic encephalitis in immunocompromised patients. Host-pathogen interactions during the chronic infection include growth of the cysts and their removal by both natural rupture and elimination by the immune system. Analyzing these interactions is important for understanding the pathogenesis of this common infection. We developed a differential equation framework of cyst growth and employed Akaike Information Criteria (AIC) to determine the growth and removal functions that best describe …

Adam17-Mediated Processing Of Tnf-Α Expressed By Antiviral Effector Cd8+ T Cells Is Required For Severe T-Cell-Mediated Lung Injury, Matthew P. Deberge, Kenneth H. Ely, Guang-Shing Cheng, Richard I. Enelow

Dartmouth Scholarship

Influenza infection in humans evokes a potent CD8+ T-cell response, which is important for clearance of the virus but may also exacerbate pulmonary pathology. We have previously shown in mice that CD8+ T-cell expression of TNF-a is required for severe and lethal lung injury following recognition of an influenza antigen expressed by alveolar epithelial cells. Since TNF-a is first expressed as a transmembrane protein that is then proteolytically processed to release a soluble form, we sought to characterize the role of TNF-a processing in CD8+ T-cell-mediated injury. In this study we observed that inhibition of ADAM17-mediated processing of TNF-a by …

Sensing Charges Of The Ciona Intestinalis Voltage-Sensing Phosphatase, Carlos A. Villalba-Galea, Ludivine Frezza, Walter Sandtner, Francisco Bezanilla

School of Pharmacy Faculty Articles

Voltage control over enzymatic activity in voltage-sensitive phosphatases (VSPs) is conferred by a voltage-sensing domain (VSD) located in the N terminus. These VSDs are constituted by four putative transmembrane segments (S1 to S4) resembling those found in voltage-gated ion channels. The putative fourth segment (S4) of the VSD contains positive residues that likely function as voltage-sensing elements. To study in detail how these residues sense the plasma membrane potential, we have focused on five arginines in the S4 segment of the Ciona intestinalis VSP (Ci-VSP). After implementing a histidine scan, here we show that four arginine-to-histidine mutants, namely R223H to …

Epigenetic Dominance Of Prion Conformers, Eri Saijo, Hae-Eun Kang, Jifeng Bian, Kristi G. Bowling, Shawn Browning, Sehun Kim, Nora Hunter, Glenn C. Telling

Microbiology, Immunology, and Molecular Genetics Faculty Publications

Although they share certain biological properties with nucleic acid based infectious agents, prions, the causative agents of invariably fatal, transmissible neurodegenerative disorders such as bovine spongiform encephalopathy, sheep scrapie, and human Creutzfeldt Jakob disease, propagate by conformational templating of host encoded proteins. Once thought to be unique to these diseases, this mechanism is now recognized as a ubiquitous means of information transfer in biological systems, including other protein misfolding disorders such as those causing Alzheimer's and Parkinson's diseases. To address the poorly understood mechanism by which host prion protein (PrP) primary structures interact with distinct prion conformations to influence pathogenesis, …

Dmsp Biosynthesis By An Animal And Its Role In Coral Thermal Stress Response, Jean Baptiste Raina, Dianne M. Tapiolas, Sylvain Forêt, Adrian Lutz, David Abrego, Janja Ceh, Francois O. Seneca, Peta L. Clode, David G. Bourne, Bette L. Willis, Cherie A. Motti

All Works

Globally, reef-building corals are the most prolific producers of dimethylsulphoniopropionate (DMSP), a central molecule in the marine sulphur cycle and precursor of the climate-active gas dimethylsulphide. At present, DMSP production by corals is attributed entirely to their algal endosymbiont, Symbiodinium. Combining chemical, genomic and molecular approaches, we show that coral juveniles produce DMSP in the absence of algal symbionts. DMSP levels increased up to 54% over time in newly settled coral juveniles lacking algal endosymbionts, and further increases, up to 76%, were recorded when juveniles were subjected to thermal stress. We uncovered coral orthologues of two algal genes recently identified …