Abstract : Infestations of the common bed bug, Cimex lectularius, have increased over a hundred-fold in the last ten years, and pest control operators in the U.S. spent almost half a billion dollars trying to detect and control them in 2012. Our knowledge of their basic biology lags far behind that of other blood-feeding insects, partially because bed bugs were not a problem from the 1940s on, and because they do not transmit pathogens. We have collaborated with scientists from JMU and North Carolina State University to answer critical questions about pesticide resistance and population genetics in bed bugs from Virginia. JMU faculty and undergraduates have also identified bacteria isolated from bed bugs. Finally, we are proposing a project that would quantify the efficacy of current control strategies and determine if we are selecting for a novel mechanism of resistance.
Dr. Heinrich uses his research to generate interest among community college students in learning about biology, which in turn creates deeper appreciation of how biology directly affects their lives. This is most successful when he takes students with him to do fieldwork in Southeast Asia, in a small post-conflict country known as East Timor. He pulls students out of their Southern California comfort zone and drops them on the other side of the planet, creating a research environment in a cultural and natural environment that is so foreign, that students drop their pretenses and reservations and truly engage in the experience. Dr. Heinrich incorporates Timorese students into the research team, and as a consequence deepens the educational and cultural experience for both guests and hosts in the country. His surveys of amphibians and reptiles is now in its fourth year, and through the effort of seven teams of students they have more than doubled the number of species known from the country—with many of those new species to science. Upon their return to the U.S., several students every semester continue the experience with specimen work, which typically leads to publication. The students who go on these trips are changed, and it is his hope that the appreciation of our natural environment and the better understanding of faraway places gained on the trip allows them to make better informed decisions in the future when it comes to nature or international affairs.
Abstract: Human fetal and neonatal mandibular form changes were examined using three-dimensional metric data, digital x-rays, geometric morphometric wireframe analysis, and non-standard measurements. The results of this research show that early mandibular growth is not a uniform timed sequence, critically influenced by factors like mechanical stimuli and the developing dentition. Additionally, the most dynamic developmental components are not the standardized dimensions that have received the most attention and the interrelationships among the structures are very complex.
Structural biology has changed the fields of biology and chemistry by connecting atomic structure to the biological function. Nine of the last 30 Nobel Prizes in Chemistry have recognized structures of biological macromolecules or the techniques to determine these structures and nearly 8,000 protein structures are deposited in the Protein Data Bank every year. However even this information is not enough for us to describe completely the functions of proteins.
My research combines in vitro biochemistry with X-ray crystallography to understand how function and structure are connected in the ubiquitin conjugating enzymes. Ubiquitination of proteins occurs in many human signaling pathways with nearly 1,000 enzymes involved in directing protein ubiquitination. I will present two studies that were key the development of a catalytic mechanism for ubiquitin transfer to the substrates and connect these previous studies to current work in the JMU Department of Chemistry and Biochemistry.
Leeann Thornton, Associate Professor of Biology at The College of New Jersey, "Plant responses to the environment: structure, function, and genetic redundancy of cytochrome P450 enzymes"
The goal of my scholarly program is to understand the molecular basis of plant growth and metabolism. Because plants are sessile, they must continually monitor external conditions and regulate metabolic processes and growth patterns to adapt to the surrounding conditions. External factors influencing plant success include light, temperature, water availability, and nutrient supply as well as attack from herbivore, bacterial and fungal pests. Stress from any one, or a combination, of these factors can decrease the growth and reproductive potential of the plant. In crop plants, growth is important for obtaining high yields of leaves, stems, and roots that we eat, while reproductive success provides the grains, seeds, and fruits in the human diet. The basic research that I do is related to the global question of how humans will continue to feed our growing population. Currently, most crop plants only achieve about 20% of their potential yield when grown in the field. That means plant biology research has plenty of room to improve the amount of food obtained from each acre of farmland.
Metabolic responses to environmental conditions require thousands of enzymes that must work in delicately balanced concert to facilitate plant growth and defense against pests. Plants with the most tightly regulated metabolism and growth are more likely to thrive. The cytochrome P450s (CYPs) are a group of enzymes that catalyze biochemical reactions in all organisms, and they are particularly important in plant metabolism. There are hundreds of CYPs in plants, and they are grouped into subfamilies based on genetic similarity. I will tell two stories that combine a molecular genetic analysis with biochemistry to describe subtle differences in apparently redundant CYPs from Arabidopsis and rice. One group inactivates a plant growth hormone in response to light and another group contributes to defensive secondary metabolites produced in response to stress and herbivory. This work provides insight into the ongoing evolution of plant genomes and the metabolites produced by CYPs.
Eria A Rebollar-Caudillo, Instituto de Ecología, Universidad Nacional Autónoma de México. “Understanding bacterial evolution: The case of Exiguobacterium, a halophilic bacteria living at the Cuatro Cienegas Basin, Mexico.”
Prokaryotes are both the most diverse and abundant organisms in the planet. The microorganisms have played essential biological and geochemical functions since the origin of life on earth. One of the central subjects in evolutionary microbiology is to understand the reasons for this enormous genetic, metabolic and ecologic diversity. The Cuatro Cienegas Basin (CCB) is part of the chihuahuan desert and it comprises several oligothrophic aquatic systems with contrasting environmental conditions. The heterogeneity of this place make it an excellent model to explore the role of ecological and geographical factors in the diversification and adaptation of prokaryotes to different environments and the molecular mechanisms that allow population divergence and differentiation. We studied the molecular evolution of 183 isolates of the Exiguobacterium genus. This genus is comprised by halophilic and alkaliphilic non-sporulating bacteria and is extremely abundant in the sediments and water from the CCB aquatic systems. The complete sequence of the 16srRNA gene and four partial housekeeping genes (citC, rpoB, recA and hsp70) were obtained. Based on the concatenated phylogeny of the four coding genes we defined three main phylogroups with contrasting genetic diversity values. These phylogroups are not specific to an aquatic system or a determined salinity. However the phylogenetic reconstruction indicates the existence of several small clusters composed by isolates from sediment or water only. In addition, Unifrac and AdaptML analyses revealed a clear differentiation pattern associated to sediment and water habitats. This work supports previous observations of niche differentiation in other bacterial lineages and represents the first work showing ecological divergence associated to water and sediment habitats.
Although once the dominant nearshore predator in Lake Superior, coaster brook trout (Salvelinus fontinalis) populations were vastly reduced by early 1900s leaving only scattered populations. The Salmon Trout River (STR) in Marquette County, MI hosts the last verified remnant and reproducing population of adfluvial coaster brook trout (coasters) along the south central shore of Lake Superior. We have used fish counting weirs (since 2000) to conduct a long-term survey of coaster adults migrating upriver, coupled with visual surveys of adults on spawning beds (since 2004). We conduct annual multi-pass electrofishing surveys of fish populations in six fixed study sites in the STR and one site each in a set of neighboring rivers to assess juvenile populations. We then observed the river becoming impacted by fine sediments emerging from watershed disturbance and so began quantifying substrate conditions (e.g., percent fine composition of sediments, sand depth, and embeddedness) in each site to assess multi-scale relationships between brook trout juveniles and the biotic and abiotic components of the river habitat. We are now conducting stream restoration to attempt to mitigate the excessive sand aggradation, which threatens major spawning areas.
These long-term surveys reveal juvenile salmonid densities in the STR are substantially lower than densities in neighboring rivers. At the regional scale (i.e., across rivers), juvenile salmonid (brook trout, coho salmon, and rainbow trout) densities varied by a factor of 3 across the tributaries, and sites with greater streambed aggradation of fine sediments had fewer juvenile salmonids. The composition of juveniles varied among rivers with low fine sediment aggradation and ranged from a brook trout only system above a barrier, to rivers where brook trout are absent and likely excluded by nonnative salmonids. At the reach scale within the STR we detect species-level longitudinal variation across the study sites, which range from higher gradient sites upstream to relatively low gradient sites downstream. Along this gradient we detected greater abundances of brook trout in lower reaches where substrates were more embedded with sand. Greater abundances of potential competitors (juvenile coho salmon and rainbow trout) were observed in upper reaches that appear to have better habitat quality. However, associated research in the STR indicates brook trout prefer less sandy habitats. These results support the hypotheses that brook trout density may be limited by biotic interactions with non-native salmonids in higher quality habitat, brook trout find competitive refuge in more degraded sites, and may be relatively excluded from some of their native rivers that are less degraded due to aggraded fine sediments.
In this talk the concept of peripheral target (e.g. eye, salivary gland, heart) mediated systems matching of neuronal circuits will be introduced by reviewing: the neurotropic factor hypothesis (Hamburger and Montalcini, 1950s; Deppmann et al, 2008) and synapse formation (Sharma, Deppmann, Harrington, et al 2010). The Deppmann lab has recently made inroads into some of the signaling mechanisms governing these processes. In particular, two unpublished studies will be discussed relating to: (1) how TNF family receptors cooperate in order to expedite cell death, restrict axon growth, and change neuron size and (2) the molecular basis for how the target derived neurotropic "signaling endosome" initiates a feedback loop to extend its own stability and signal duration.
Plants store about half of their daily photosynthate as starch in chloroplasts then degrade it each night, primarily by beta-amylase, to supply the plant with reduced carbon when photosynthesis isn’t possible. There are nine beta-amylase-like genes (BAMs) in Arabidopsis thaliana. Six of the BAM proteins are plastid-localized including BAM3 and BAM9. BAM3 is catalytically active and appears to play an important role in nighttime leaf starch degradation. In contrast, BAM9 is catalytically inactive and is expressed only at the beginning of the day period. Knockout mutants lacking BAM9 have a mild starch-accumulation phenotype leading us to suspect that BAM9 plays a regulatory role in daytime leaf starch metabolism. In order to generate testable hypotheses regarding BAM9’s function, we aligned BAM9 orthologs from six eudicots with a corresponding set of BAM3 orthologs and searched for uniquely conserved amino acids. We then mapped these amino acids onto a PHYRE-generated 3D model of BAM9. Based on this analysis, we hypothesize that BAM9 binds maltose and another protein, but not starch. We are presently using NMR, phage display, and starch-binding assays to test these hypotheses.
Lipopolysaccharide (LPS) is a defining component of the outer surface of Gram-negative bacteria. Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen, responsible for acute infections in immunocompromised hosts and chronic lung infections individuals with cystic fibrosis. P. aeruginosa LPS is one of its recognized virulence factors: strains from acute infection generally express a complete LPS, while those from chronic infections in CF are generally LPS-defective. This seminar will describe the synthesis of P. aeruginosa LPS and explain how this complex molecule is regulated.
S100 proteins are small, dimeric calcium binding proteins that contain two EF-hands per monomer. While these proteins are expressed plentifully in a tissue-specific manner, the cellular functions of most S100 proteins remain understudied. Here, I will talk about work to elucidate the solution structure of S100A1 in varoius biologically relevant states.Multidimensional NMR spectroscopy techniques were utilized to solve the solution structure of S100A1 in its Ca2+-bound form. The protein folds as a symmetric homodimer, with an X-type helix bundle comprising the dimer interface. A large conformational change, involving the reorientation of helix 3, accompanies S100A1 calcium binding. This change exposes a previously hidden hydrophobic pocket which is the general target protein binding site and specifically the binding site for the calmodulin binding domain of the ryanodinereceptor. The solution structure of S100A1 bound to a peptide from this region, along with whole-cell calcium transient measurements in S100A1 knockout mice, provide evidence that S100A1 directly increases RyR1-driven calcium release by binding to a discreet area on the cytoplasmic face of RyR1. This binding event is driven by both hydrophobic and ionic interactions between S100A1 and the RyR peptide. A competition between S100A1 and calmodulin for the same region of RyR1 represents a cellular mechanism of modulating SR Ca2+ release in myocytes, and as such, represents a new molecular pathway in which to combat heart failure.
Infectious diseases have emerged as a significant threat to wildlife. Environmental change is often implicated as an underlying factor driving this emergence. It is therefore important to identify the environmental factors that can influence host-pathogen systems and their underlying mechanisms. The emerging pathogen Batrachochytrium dendrobatidis (Bd) is a clear example of the negative effects infectious diseases can have on wildlife. Bd is linked to global declines in amphibian diversity and abundance. However, there is considerable variation in population-level responses to Bd, with some host species experiencing marked declines while others persist. Aspects of the abiotic environment may play a role in this variation. My research used populations of pond-breeding chorus frogs (Pseudacris maculata) to test if three rapidly changing environmental factors, nitrogen (N), phosphorus (P), and temperature, influenced the presence, prevalence, and severity of Bd infections.Monitoring from 20 frog populations found high Bd presence and prevalence in breeding adults. Adult frogs experimentally exposed to Bd showed high levels of mortality. Yet chorus frog populations have persisted for several years. Presence, prevalence, and severity of Bd infections were not correlated with aqueous concentrations of N or P. There was, however, support for an annual temperature-induced reduction in Bd prevalence in newly metamorphosed larvae. A mathematical model of chorus frog population growth suggests that this annual temperature-induced reduction of Bd infections in combination with rapid host maturation may help chorus frog populations persist despite high rates of disease related mortality. These results provide evidence that water temperature may play an important role in enabling chorus frogs to persist with this pathogen and lay the groundwork for future research examining how environmental factors and host life history can interact to enable host populations to persist with a “virulent” pathogen.
The headlines read, “U.S. pushes for more scientists, but the jobs aren’t there” (Washington Post, July 7, 2012). Traditional academic jobs are scarcer than ever. Once a primary career path, only 14 percent of those with a PhD in biology and the life sciences now land a coveted academic position within five years, according to a 2009 NSF Survey. If this is the case, then what alternatives are there to traditional career paths for those with doctorates in biology and medicine? Perhaps, a career in public education warrants a look.
How does one parlay a major in biology from James Madison University into a meaningful and productive career in public education that is both personally and professionally fulfilling? What does such a career look like? Is a major in biology good preparation for a career in public education and STEM? How can research interests in biology still be an integral component of this career path?
Explore these questions and more in this seminar conducted by Dr. Hays B. Lantz, Jr., former Assistant Superintendent of Schools for STEM Education, Baltimore County Public Schools, Maryland. From examining the teaching of biology in public schools to designing and implementing instructional programs in STEM PK-12, participants will have an opportunity to explore how a major in biology can lead to a career in public education that is a dynamic and rewarding lifelong endeavor.
Both scientists and laymen alike are familiar with symbioses: Insects pollinate flowers, ants defend acacias, and many vertebrates rely on symbiotic gut microorganisms for digestion. Among the best publicized and most sensationalized of symbioses are cleaning symbiosis mutualisms. Images of small, colorful shrimp or tiny precocious fishes cleaning parasites and necrotic skin from large otherwise-aggressive fishes are well known thanks to fantastic reporting from National Geographic and the Discovery Channel. However, a common misconception regarding mutualisms is that they are relatively benign, cooperative interactions in which both partners always benefit. To the contrary, many mutualisms are best viewed as reciprocal exploitation in which each partner benefits by exploiting its counterpart to the fullest extent possible. In such interactions, there is obviously the potential for overexploitation. However, mutualisms are common in nature, so it stands to reason that there are mechanisms in place that allow each partner to prevent overexploitation.
For the past 15 years, my colleagues and I have studied the only described freshwater cleaning symbiosis in which annelid worms (Annelida: Branchiobdellida) clean the gills of crayfish, resulting in increasing growth and decreased mortality of the crayfish host. While our system is somewhat less well publicized—and some might even misguidedly argue, less charismatic—than the well-known coral reef cleaning symbioses, it has the benefits of being common, accessible, and extremely amenable to experimentation. During my seminar, I will describe the nature of this symbiotic interaction including costs and benefits to both partners and the mechanisms through which they are accrued, discuss the controls that prevent over-exploitation by each partner in the symbiosis, and demonstrate how the symbiosis between crayfish and branchiobdellid produces effects that cascade through stream systems, affecting both community structure and ecosystem processes.
Malaria is a major global health problem, causing close to a million deaths and clinical illness in hundreds of millions of people every year. The malaria parasite, Plasmodium, has developed resistance for most antimalarial drugs and there is a dire need to expand our arsenal of antimalarial drugs to protect millions of people worldwide. However, a major strategic hurdle to antimalarial drug development is our grave lack of understanding of Plasmodium biology, as almost 50% of its genome (approximately 2500 genes) codes for “proteins with unknown functions”. Functional characterization of the Plasmodium genome is therefore critical to identify new and high-value therapeutic targets. We have pioneered a forward genetic approach, using transposon-mediated insertional mutagenesis, to rapidly identify crucial parasite genes and facilitate novel antimalarial therapeutic intervention strategies.
Katrina Gobetz, JMU – “Burrowing as a function of ontogeny and colony in semifossorial mammals“
Study of burrowing mammals applies to organisms at various levels. Digging strategy of a species is a gauge for evolutionary patterns of burrowing in more basal mammals, and behavior of burrowers affects species co-using a burrow ecosystem. Burrowers traditionally fall into forelimb-, head-, and tooth-digger categories. My research entails breaking down digging behavior into individual movements, analyzing the sequence, and illustrating it kinematically. My work on semifossorial eastern chipmunks (Tamias striatus) and lab strain Norway rats (Rattus norvegicus) suggests that the paradigm-like categories only partly explain burrowing behavior, that digging strategy changes with ontogeny, and that juveniles are the most active diggers.
Chipmunks are morphologically unchanged from ancestral squirrels of 25MYA, and digging strategy may be similarly basal. Analysis of chipmunks from two regions suggests that head and teeth are necessary digging aids, especially in juveniles, and juveniles have more complex movement sequences. Similar patterns occur in the rat, a non-native with persistent burrowing habits that make it a bona fide nuisance. Burrowing is instinctive in Sprague Dawley rats, which separate into active “alpha” diggers or “betas” that rarely attempt excavation. Division appears to correlate with age and sex, with highest alpha concentration among youngest age classes. In one 68-rat sample, all 2wk-old nursing pups and 48% of weaned pups were alphas with obligatory head/tooth digging. Burrowing activity lessens with age in males but persists in females, echoing wild rats’ harem-type colonies. In juveniles, head/limb parameters affect movement, but it is unclear whether “babyish” proportions limit or facilitate digging. My students and I currently test hypotheses that burrowing begins during nursing, and that juveniles contribute significantly to creation of burrow ecosystems.
Dr Mark Gabriele, JMU – “Assembling Functional Auditory Circuits in the Developing Brain Prior to Experience”
Hearing, performed by the auditory system, is a vital sense and critical for speech and language acquisition. Despite significant incidences of hearing loss and innovative treatment strategies (e.g. implantation devices), fundamental questions remain unaddressed concerning auditory circuit formation. The auditory system is functionally organized into topographic connections that preserve tonotopy, or frequency mapping established in the cochlea. The accurate alignment of these projection maps defines functional compartments necessary for processing sophisticated auditory tasks. The primary aim of my research laboratory is to determine the developmental mechanisms that guide accurate topographic and patterned projections to the auditory midbrain, or inferior colliculus (IC). Previously, we have shown that multiple developing inputs to the IC exhibit mature projection patterns prior to hearing onset (postnatal day 12 in mouse). We hypothesize that the spatial resolution necessary to establish this precise blueprint of connections in the absence of experience requires close cell-to-cell signaling via a family of membrane-tethered guidance molecules, the Eph-ephrins. We have found that several members of this signaling family are expressed in the nascent IC (EphA4, ephrin-B2, and ephrin-B3), and further, their graded and modular expression correlates temporally and spatially with known developing IC projection patterns. Utilizing fluorescent axonal tracing methods in control (C57BL/6J) and Eph-ephrin mutant mice (EphA4lacZ, ephrin-B2lacZ, ephrin-B3lacZ, ephrin-B3null), we report significant topographic mapping errors in the development of ascending inputs to the IC. Current work aimed at establishing an organotypic in vitro stripe assay will provide further insights concerning the specific influences various Eph-ephrin members elicit on growing auditory axons. Finally, we are currently exploring a variety of physiological and behavioral tests to assess any functional consequences that may result from the altered circuitry observed in our Eph-ephrin mutants. Mechanisms learned from these developmental studies will not only help guide new strategies for treating the hearing impaired, but are also applicable to fields of neural plasticity, recovery, and regeneration.
Cassidy Turner, McGuire Veterans Hospital - "Hospital Dentistry: Exploring the Oral Health Systemic Health Connection"
Abstract: Periodontal disease and dental caries are diseases that not only affect oral health but systemic health as well. 23% of the US population age 25-64 has untreated dental caries and 8.5% of the US population age 25-64 has periodontal disease. Untreated dental caries can result in tooth loss, chronic pain, localized infection, systemic infection, or, in extreme situations, even death. Uncontrolled periodontal disease has been linked to poor glycemic control in diabetics, heart disease, and low birth weights/premature births in pregnant women who have uncontrolled periodontal disease..
Eva Strawbridge - JMU Math Department - "Twisted DNA and Wiggling Worms: The Mathematics of Slender Bodies"
Abstract: How can a worm or snake crawl, swim, (or, yes, even fly)? How does a vine twist and grow? Why does a plasmid of DNA twist up on itself? Slender objects, both passive and active, are a pervasive phenomenon in biological systems. Is there then, some abstract way in which we may view or model any of these organisms, materials, or biomolecules which might capture certain large scale behaviors common to them all? In this talk we will briefly discuss one mathematical model of a slender body and how this model is being applied and extended to new, multi scale research in animal locomotion to answer the burning question: How do worms wiggle?
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Title: "A Genomic Perspective of Bacteriophages Through the Development of Computational Tools".
Bacteriophages (viruses that infect bacteria) are the largest knownreservoir of novel genetic sequences on planet Earth. These viruses are critical for carbon cycling in the environment, useful as diagnostics in the laboratory, and are being explored as anti-bacterial agents in the clinic.
Bacteriophage genomes have mosaic architectures and are replete with small open reading frames of unknown function, presenting challenges in their annotation, comparative analysis, and representation. We are developing a new bioinformatic tool, Phamerator, that assorts protein-coding phage genes into phamilies of related sequences using pairwise comparisons to generate a database of gene relationships. This database is used to generate genome maps of multiple phages that incorporate nucleotide and amino acid sequence relationships, as well as genes containing conserved domains. Phamerator also generates phamily circle representations of gene phamilies, facilitating analysis of the different evolutionary histories of individual genes that migrate through phage populations by horizontal genetic exchange. Phamerator represents a useful tool for comparative genomic analysis and comparative representations of bacteriophage genomes. The analysis of these genomes is an important component of a number of courses in our department (Viral Discovery, Viral Genomics, Bioinformatics, and Genomics). The contributions of these students will be highlighted.
Title: "What doesn’t kill you…: cell-stress response in C. elegans and its implications for disease development and treatment".
Maintaining cell viability and function is a complex and dynamic process, particularly in the face of the significant and persistent stresses that all cells face throughout their existence. Cell stress can take many forms, all of which trigger responses ranging from complete resolution of the stress to cell death. Poorly regulated stress responses are closely linked to a multitude of diseases, including neurodegeneration and cancer, therefore our understanding of cell-stress management is essential to our understanding of these disease pathologies. We study cell-stress response in the model organism C. elegans., in particular, the management of stress associated with misfolded proteins. Through the use of RNA interference and GFP-fusion protein expression, we are able to induce misfolded protein stress in C. elegans and evaluate the subsequent response. Our results are providing insights into how specific cell types handle misfolded protein stress and how these responses differ from cell-type to cell-type, resulting in rescue or death. The accumulation of misfolded proteins is a hallmark of many neurodegenerative diseases, including Huntington’s and Alzheimer’s; we hope our understanding of how C. elegans handles this stress will provide insights into the function of homologous stress-response systems in human cells, and how they work, or don’t work, in the face of these diseases.
Title: "Return of the Giant: Experimental Seedling Trials with American Chestnut"
American chestnut was once a dominant canopy species in many eastern deciduous forests. Unfortunately, this ecologically and economically important species has been eliminated from the forest canopy for over sixty years due to an introduced fungal pathogen. We are almost at the point of introducing blight-resistant chestnut hybrids into our forests. However, little is known about American chestnut’s ecological niche or whether hybrids have retained American chestnut ecophysiological characteristics and growth. We have been experimenting with two levels of light and soil in parallel field and greenhouse studies for the past four years. Thus far, we have found that optimal sites for planting American chestnut hybrids are in small gaps located within upper slope, ridge sites. Seedlings performed relatively well, had good survival rates, and were the most competitive with tulip poplar, their major competitor, under these conditions. In addition, we did not detect a significant difference between American chestnut and the hybrids for any performance parameters measured.
Title: “Form Makes Function” – The Road to a Tissue-Engineered Cornea.
Corneal disease is the second-leading cause of blindness in humans worldwide and the only current treatment is corneal tissue transplantation. This results in high demand for cornea tissue, which currently exceeds supply, making a tissue engineered cornea highly desirable. One approach to tissue-engineering a cornea is based upon the concept that various components of a tissue act in concert to provide the specific functions of a tissue. This tissue-engineering approach includes selecting the appropriate cell type(s), appropriate scaffold material, and the appropriate signals (such as growth factors, mechanical stimuli, flow conditions, etc.), which all contribute to formation of the three-dimensional (3D) architecture of a functional tissue. An important feature of cornea tissue is the need to be transparent, so an in vitro engineered cornea must also be transparent to be useful. Research in my lab is currently focused on understanding and controlling the cell phenotype of corneal keratocytes, the cell type found in the stromal layer of cornea tissue, and the cell type that plays an important role in maintaining cornea transparency. We employ a rabbit cornea tissue model to study how various artificial scaffolds, and biochemical signaling molecules can influence the functional differentiation of corneal keratocytes as these cells move through a wound healing phenotype toward a fully differentiated phenotype that yields a transparent tissue. In addition to studying cornea tissue engineering, we hope this work, in conjunction with our collaborators, will contribute to a better understanding of corneal wound-healing mechanisms associated with corneal haze problems resulting from eye surgeries, and provide a model system for studying new ophthalmic drugs.
Andy Johnson, Univ. Penn
Title: "Metabolic regulation during the immune response" Watch video
The immune system attempts to eliminate cancerous cells and invading pathogens, but evasion tactics by these diseases can result in persistent tumors or infections. The continued presence of diseased cells in these contexts leads to an over-stimulated, dysfunctional immune state termed exhaustion. Exhausted immune cells have an impaired ability to fight infections compared to the cells generated following vaccination. These differences are at least partially caused by inhibitory receptors on the exhausted cells that are believed to send negative signals that block immune activation. Exhausted cells also display altered energy metabolism just as exhausted humans do during prolonged exercise such as a triathlon. Metabolic processes can regulate the development and function of many cell types including those of the immune system. These characteristics of exhausted immune cells may be linked as inhibitory receptors were recently shown to block pathways that control metabolic processes. Importantly, though originally observed in a mouse model of chronic infection, clinical researchers also found that blocking inhibitory receptors partially reverses immune exhaustion, enhancing the immune system’s ability to fight cancers including AML.
My goal is to understand how inhibitory receptors and metabolic pathways regulate immune cell function in order to find ways to reverse immune exhaustion and help the body’s natural defenses eliminate cancer and chronic infections. To address this, I have begun analyzing the metabolic pathways active in exhausted cells that express different combinations of inhibitory receptors. I have exciting preliminary results showing that particular subsets of exhausted cells have decreased and delayed activation of a central regulator of metabolism. I now plan to monitor this metabolic pathway following blockade of inhibitory receptor activity and to enhance this metabolic pathway using clinically proven pharmaceutical drugs. Ultimately, this will lead to a more complete reversal of immune exhaustion by directly targeting the dysfunctional metabolic processes that are required by the immune system to destroy cancerous or infected cells.
Kimberly Terrell, National Zoo
Title: "Investigating the Influence of Projected Climate Change on Hellbender Physiology". Watch video
The Appalachian region is home to half of the United States' salamander species, including the hellbender (Cryptobranchus alleganiensis), but populations throughout this area are mysteriously vanishing. Climate change is globally linked to enigmatic amphibian declines and will likely impact Appalachian salamanders and other ectothermic species adapted to cool microclimates. This talk will focus on an ongoing study at the Smithsonian Conservation Biology Institute (Washington, DC) that examines the influence of changing temperature on hellbender immune function and metabolism. Working collaboratively with state, federal, academic and NGO partners, we are using both lab and field-based approaches to determine if climate change can act synergistically with other stressors (e.g., water quality) to threaten salamander survival. These studies will establish certain physiological limits of (or opportunities for) climate change adaptation in hellbenders and may provide insight into the enigmatic declines of Appalachian amphibians.
Title: "Role of Brain Stem Serotonin in the Cardiovascular Response To Stress In Rats - Applications to Sudden Infant Death Syndrome (SIDS)"
Dysfunction in serotonin (5HT) neurotransmission in the brainstem of infants may disrupt protective responses to stress and increase the risk for Sudden Infant Death Syndrome (SIDS). The raphé pallidus (NRP) and other brainstem nuclei are rich in 5HT and are thought to mediate stress responses, including increases in blood pressure (BP) and heart rate (HR). Determining how 5HT neurotransmission in the brainstem mediates responses to stress will help to explain how dysfunction in neurotransmission could increase the risk of SIDS. It was hypothesized that alterations in neurotransmission in the NRP, specifically activation of the 5HT-1A receptor subtype, would block cardiovascular responses to various types of exogenous stress. Using aseptic techniques, male Sprague-Dawley rats were instrumented with radiotelemetry probes which enabled non-invasive measurement of BP and HR. An indwelling microinjection cannula was also stereotaxically implanted into the NRP for injection of drugs that altered local 5HT neurotransmission. Following a one week recovery period, rats were microinjected with either muscimol (GABA-A receptor agonist), 8-OH-DPAT (agonist to the inhibitory 5HT1A receptor), or a vehicle control (artificial cerebral spinal fluid; ACSF) immediately prior to exposure to one of three stressors: handling, air jet, or restraint. Physical handling and restraint of the animal were designed to elicit a mild and a maximal stress response respectively; while an air jet directed at the rat’s face was used to provoke a psychological stress that did not require physical contact. All three stressors elicited similar and significant elevations in HR and BP following ACSF that persisted for at least 15 min with BP and HR elevated by ∼14.0 mmHg and ∼56.3 bpm respectively. The similarity in the stress responses suggest even mild handling of a rat elicits a maximal sympathoexcitatory response. The stress response was abolished following 8-OH-DPAT or muscimol microinjection suggesting the cardiovascular responses to stress are mediated by the NRP and likely involve the 5HT-1A receptor. Impairment in 5HT1A receptor function in the NRP likely impairs the normal cardioprotective responses to stress and may contribute to the etiology of SIDS.
Butch Brodie, UVA
Title: "Predator-prey arms races between snakes and newts from molecules to landscapes". Watch video
Arms races between predators and dangerous prey can lead to rapid and elaborate counter-adaptation. Newts of the genusTarichapossess the sodium channel blocker tetrodotoxin, which is lethal to most predators. Garter snakes have repeatedly evolved resistance to TTX through their ecological interaction with toxic newts. Sodium channel genes are highly conserved across vertebrates, yet garter snakes have evolved resistance through a few key mutations in these proteins in a very short evolutionary time. Snake species around the world have evolved TTX resistance through the same set of mutations, painting a clear picture of constraint driven convergent evolution at the protein level. Understanding the molecular mechanism of adaptation helps explain the dynamics of predator-prey arms races in this system, wherein predators some times "win" the race, but prey never do.
Abstract: Molly Bletz
Title: "Transmission and persistence of probiotic skin microbes on red-spotted newts"
The infectious disease, chytridiomycosis, is considered one of the leading causes of these enigmatic amphibian declines in pristine areas. Caused by the cutaneous fungal pathogen Batrachochytrium dendrobatidis (Bd), chytridiomycosis is decreasing amphibian biodiversity, driving >200 species to extinction across many continents. Cutaneous mutualistic bacteria are a critical part of an amphibian’s defense against Bd infection. The use of these beneficial bacteria as probiotics for susceptible species is likely the most feasible conservation strategy.
It is well documented that amphibians maintain populations of microbiota on their skin; however, how these particular beneficial species are acquired, maintained and transmitted is not fully known. Therefore, the aim of the proposed research is to investigate the transmission and maintenance of beneficial bacteria on amphibians and the necessity of environmental bacterial reservoirs for probiotic conservation methods to allow continued resistance to Bd. Using outdoor artificial ponds housing red-spotted newts, I plan to manipulate two factors, presence and absence of a probiotic bath and presence and absence of a probiotic environmental reservoir.
Over seven weeks, I will test how these factors influence newt susceptibility to Bd infection. Investigating maintenance and transmission can determine whether amphibians are dependent on environmental microbial populations for maintaining these cutaneous bacteria or if the microbial community is self-sustaining once acquired. Transmission and maintenance also have strong implications for probiotic conservation strategies and can provide vital insight in developing effective conservation strategies to help susceptible species.
Title: "Cutaneous microbial community dynamics of amphibians"
Emerging infectious diseases are a major threat to biodiversity. The fungal disease chytridiomycosis has been documented causing amphibian extinctions and declines globally. Indeed, the disease is considered the largest disease threat to biodiversity. One defense possessed by amphibians to combat chytridiomycosis is a cutaneous bacterial community. A number of cutaneous bacterial species have been determined to inhibit Batrachochytrium dendrobatidis (Bd), the causal agent of chytridiomycosis; however, their relative abundance within their community is unknown. The stability of amphibian bacterial communities is also unexplored. Stability is defined as resistance to a disturbance; resilience is defined as recovery from a disturbance and constancy is defined as temporal stability. Using 454 pyrosequencing, I propose to investigate the structure and stability of cutaneous bacterial communities of the red-backed salamander (Plethodon cinereus) in regards to several major perturbations: moving individuals from the field to the laboratory, housing individuals with and without an environmental reservoir, and infection with B. dendrobatidis. As another objective, I will determine how the abundance of culturable species compares to that of total bacteria present in the community since most bacterial species are not easily cultured. This objective will establish if the stability of a cultured community is an adequate indicator of total community stability. I also propose to investigate temporal constancy to determine if temperature variations that mimic climate change projections influence bacterial communities’ structure and function of the eastern hellbender (Cryptobranchus alleganiensis alleganiensis).
Clint epps, OSU
Title: "Contrasting connectivity across species and time scales for large mammals in East Africa" Watch video
Connectivity is often touted as a solution to help maintain biodiversity in
reserves and prevent rapid loss of genetic diversity. However, dispersal abilities vary widely across species and the effect of landscape on movement and gene flow is unknown for most species. Thus, the basis for attempting connectivity conservation among specific reserves is often unclear. East African reserves are often cited as a classic example of protected areas isolated in a sea of human activity, but little is known about the potential for connectivity among reserves. Our research group has used both field surveys of animal occurrence and population genetic data to describe and contrast patterns of connectivity for large mammals in Tanzania. In this seminar, I will present comparative estimates of long-term gene flow for four species of large herbivorous mammals, as well as analysis of changes in connectivity for African elephants from historical through present-day timeframes. Our findings will help frame the discussion regarding connectivity and the allocation of conservation resources.
Abstract: Caylin Murray
Title: "The effect of cellular stress on the unfolded protein response in C. elegans" Watch video
Cells are constantly dealing with stresses that threaten to disrupt the homoeostasis required for survival. Certain stresses can result in accumulations of misfolded protein in the endoplasmic reticulum (ER), an organelle central to the maintenance of cell viability. Responsibilities of the ER include: post-translational modification of folded proteins, chaperone-guided folding of nascent polypeptide chains, and the synthesis of lipids and steroids. When proper protein folding is inhibited in the ER, highly conserved mechanisms are engaged to minimize the physiological stress on the organelle. One such mechanism is the unfolded protein response (UPR). The UPR can be broken down into three responses: First, the UPR works to restore homeostasis by decreasing translation of proteins; next, there is an increase in the production of molecular chaperones that bind directly to proteins to prevent their misfolding; finally, the UPR degrades improperly folded proteins that have accumulated within the ER. Even with these controls in place, the environment in the ER may become too toxic for cell viability. In these cases, the UPR shifts focus to death and disposal of the cell by apoptosis or autophagy. The goal of this study is to explicate the balance between autophagy and apoptosis in response to the UPR through manipulation of the C. elegans protein Inhibitor of Cell Death-1 (ICD-1). Loss of ICD-1 appears to induce an accumulation of misfolded protein in the ER, resulting in the induction of the UPR. We will characterize the scope of the UPR in C. elegans lacking ICD-1 by removing ICD-1 from worms deficient in specific aspects of the UPR. Ultimately, we hope to learn how the UPR is controlled and extrapolate these finding to the human system, which contains highly conserved UPR mechanisms relative to C. elegans.
Title: "The effect of Dengue Virus E protein on chondrocyte immune response" Watch video
Dengue Fever and, the more severe, Dengue Hemorrhagic Fever has been a problem for people living in tropical regions with elevated endemic mosquito populations. 50-100 million people are currently thought to be infected by this pathogen every year. The disease causes a number of symptoms ranging from rash, a mid-grade fever and arthralgia (joint pain), to hemorrhaging of internal organs and death in extreme cases. My research focuses on arthralgia and its association with cells known as chondrocytes, the cell population present in cartilage tissue, as well as characterizing potential receptors of the Dengue virus in macrophages. To facilitate these studies, I will be using an envelope protein of the Dengue virus to stimulate an immune response in both cell types and checking gene expression patterns over a time course using quantitative Real-Time PCR. Once genes have been identified in response to envelope protein, I will be running protein expression analysis using ELISA or immunofluorescence microscopy. In our macrophage studies we will be selectively blocking receptors known to facilitate viral uptake using antibodies and blocking ligands. Gene expression analysis and protein changes will be monitored in macrophages following incubation with viral envelope protein as well. These studies hope to elucidate the immune response generated by chondrocytes exposed to the viral envelope protein, and determine the effects of receptor blocking in macrophages to gain a better understanding of dengue pathogenesis.
Title: "Determining the Role of a Conserved Hypothetical Protein in the Erythrocytic Life Cycle of Plasmodium falciparum" Watch video
Malaria is a disease that causes 300-500 million cases annually, approximately 1 million of these cases resulting in death. Malaria is an infection caused by the parasitic protozoan Plasmodium. There are 5 species that can infect humans, Plasmodium falciparum causing the majority of the fatalities. The genome for Plasmodium falciparum was sequenced in 2005 and 60% of the genome encodes for unknown proteins. The last five years have lead to the development of several genetic tools for manipulating the genome, and I will be studying a mutant strain of Plasmodium falciparum. A forward genetic screen created a mutant phenotype that severely attenuated the growth in the blood stages. I will be investigating the function of the protein that the mutation disrupted using bioinformatics, examining localization and expression, and investigating protein to protein interactions. I will also be investigating the phenotype of the mutant strain, examining the erythrocytic life cycle in culture.
Title: "Synthesis, Antibacterial Activity, & Structure-Function Analysis of a Novel Series of Multi-Headed Amphiphiles" Watch video
In the US, approximately two million patients a year acquire a hospital-acquired infection during their stay, leading to almost 100,000 deaths. An increasing number of these infections are caused by multi-drug resistant organisms. Development of novel, potent antimicrobial compounds could be used in eliminating or reducing potential pathogens in the hospital setting. As a continuation of our previous research on bicephalic amphiphiles, which correlated antibacterial activity with head group arrangement and chain length, the antimicrobial activity of two novel series of amphiphiles was investigated. Amphiphiles of series “A” have a tri-substituted arene core. Attached to the arene core are three head groups, each with a hydrocarbon tail (from 8-16 carbons) of the same length linked to each head group. Amphiphiles of series “B” are a structural variation of “A” with one of the head groups a pyridine without a hydrocarbon tail. These series of amphiphiles were assayed for antimicrobial effectiveness against Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa, and Escherichia coli by performing standardized minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays. MIC and MBC values for these amphiphiles were in the low micromolar range. Specifically, the compound M-P,12,12, from series “B” (meta-pyridine, 12 carbon chain, 12 carbon chain) was most effective for all strains tested, with MIC and MBC values of 2mM for S. aureus, 2mM for E. faecalis, 4mM for E. coli, and 8mM for P. aeruginosa. In addition to being the most effective compound, the MIC values of M-P,12,12 were less than control compounds DTAB, CTAB, and Lysol. The MIC of M-P,12,12 for P. aeruginosa, a difficult to treat organism, was 4 fold less than the MIC of Lysol for P. aeruginosa (8mM and 32mM, respectively). Structure-function analysis has identified simple trends in the series of amphiphiles tested. Amphiphiles of series “A” were more effective against gram-positive bacteria. However, amphiphiles of series “B” were more effective than amphiphiles of series “A” against all strains tested. Antimicrobial activity of amphiphiles of series “B” was found to be reliant on the hydrocarbon chain length of the substitutions, with higher MIC values when chain length was shorter or longer than 12 carbons with all strains tested. This research builds upon initial discoveries regarding structure and bioactivity to identify structures with the most potent antimicrobial activity while remaining safe.
Title: "Soil as a source of the fecal indicator, Enterococci, in a coastal watershed. " Watch video
The Clean Water Act of 1972 initiated a raised awareness of the extent of the pollution in U.S. waters and the need for monitoring and identifying sources of contamination. Surface water quality is routinely evaluated using fecal indicators, such as Enterococcus spp. Recent studies in a south Texas watershed showed that fecal bacteria were being transported to water via agricultural land runoff following rainfall, suggesting that soil, rather than fecal material, may be a source of these bacteria. In this study, soils from fields under different crop covers have been sampled to determine seasonal levels of enterococci and species of enterococci have been identified sing the BIOLOG™ Microbial Identification System. A series of laboratory experiments will be conducted to evaluate the ability of enterococci to survive in soil, using a South Texas soil…name it. . Top soil samples will be placed in small columns and inoculated with environmental and ATCC strains of a species of Enterococcus, which has been isolated from both soil and water in the watershed. Experiments will be set up at several temperatures (40o, 25o, 10oC) and moisture (dry or equivalent to 2.5 cm rainfall). Enterococci will be enumerated at several time intervals using standard membrane filtration on selective media for Enterococcus spp. (mEI), following extraction from soil. Field sampling showed higher numbers of enterococci in soil during cooler months and preliminary lab results indicate that survival of enterococci in soil is affected by temperature, with greater persistence at lower temperatures. This data support the hypothesis that soil can act as a reservoir for fecal indicator bacteria in the environment.