Undergraduate Merit Fellowship Mentors
Anatomy and Neurobiology
Detlef Heck, Ph.D.
The research project will use automatic video tracking technology for a detailed quantitative investigation of social and motor behavior in normal mice and mouse models of heritable brain disorders (autism and ataxia). The goal is to identify quantifiable deficits in complex social and simple motor behaviors in mouse models of human brain disorders. The project involves the handling of mice, performance of behavioral tests, recording of the video data and analysis of the data using statistical analysis software packages (Sigmastat, SPSS or SAS). All activities will be performed in under the supervision of the PI (Dr. Heck).
Matt Ennis, Ph.D.
My primary interests are centered on the functional organization and physiological properties of neural networks involved in nociception/analgesia processing and the chemical senses (i.e., olfaction and gustation). My research utilizes an integrative, multidisciplinary approach combining tract tracing, immunocytochemistry, immediate early gene expression and electrophysiology to delineate cellular and circuit properties of functionally defined networks. Additional details can be found on my websites: http://www.hayar.net/EnnisLab
The major current projects in my laboratory are:
- Regulation of Brainstem Opioid Analgesic Circuits. A well defined brainstem-spinal cord circuit is known to play a key role in opioid-mediated analgesia. We are investigating how higher levels of the CNS (cortical and subcortical sites) involved in emotions, motivational state and cognitive processing can regulate this brainstem analgesic circuit to allow for state-dependent modulation of pain thresholds. We are also investigating how sweet and fatty components of mothers milk produces profound opiate receptor-dependent analgesic and calming effects in newborn rats and humans.
- Synaptic Integration and Information Processing in the Olfactory Bulb. We are investigating how neuronal membrane properties and extrinsic/intrinsic neurotransmitter systems modulate information processing and output from the olfactory bulb circuit using functional imaging and neurophysiology approaches in vivo and in vitro.
- Integration in the Olfactory Bulb (OB)-Piriform Cortex (PC) Circuit. Olfactory receptor neurons that express a single common odorant receptor project to one glomerulus in the OB. The glomeruli thus form a map that mirrors receptor activity. Different odors stimulate different patterns of glomerular activity. The OB and PC comprise the major components of the neural network that decipher such patterns to arrive at the recognition of an odor. The goal of this research is to understand how glomerular activity is relayed to, and processed within PC using neuroanatomical and neurophysiological approaches.
Kristen Hamre, Ph.D.
Depending upon the interest of the student, there are two possible types of techniques that a student could learn. One is that the student could learn about behavioral testing of mice to examine both baseline and alcohol-mediated behaviors that measure such parameters as anxiety and balance/ coordination. Second, through the analysis of development a student could learn techniques such as genotyping through the use of PCR and histological processing of tissue.
Scott Heldt, Ph.D.
Our lab's primary research interest is in understanding the neural systems mediating fear and anxiety in the mammalian brain. Our lab also examines the functional role of regional GABA receptors in normal and drug-induced behaviors. We use a multidisciplinary approach to examine the molecular, cellular, pharmacological, and genetic processes influencing fear- and drug-related neural mechanisms. Some of the tool and techniques we employ include:
- In situ hybridization
- Receptor autoradiography
- Western blotting
- In vivo and in vitro viral vector techniques
- Systemic and local drug injections
We use wildtype and transgenic mice as model organisms, including conditional knockout mice. Behavioral tests employed for investigating experimental manipulations including, the elevated plus maze, Morris water maze, open field apparatus, passive avoidance, drug-induced seizures, light/dark box, forced swim test, horizontal wire test, prepulse inhibition, rotarod apparatus, startle, fear-potentiated startle, and conditioned freezing.
Marcia Honig, Ph.D.
My research is focused on understanding how neurons establish appropriate connections during development. As part of our previous work focusing on somatosensory neurons and using chick embryos as a model system, we identified the chicken homolog of cerebellin (Cbln) 2. Cblns are a family of four secreted proteins that, despite their name, are widely expressed in the nervous system and have been shown to promote synapse formation. In accord with this, we found that Cbln2 is expressed by specific subsets of neurons in the sensory ganglia and by neurons located in regions of the spinal cord where those sensory neurons project. To study Cbln function, we have transitioned to using mice as our experimental system because of the wealth of available genetic resources. Characterization of the distribution of Cblns1, 2, and 4 in the mouse spinal cord has demonstrated that each Cbln is expressed by discrete populations of neurons in the dorsal horn. To investigate the role of Cblns in the formation of sensory neuron synapses in the dorsal horn, we plan to examine how synaptic connections formed by specific kinds of sensory afferents with their targets in the dorsal horn are altered in Cbln1-null and Cbln2-null mice, through a collaboration with Jim Morgan at St Jude's who has generated a variety of such knockout mice.
We are also currently developing a novel mouse model of mild-to-moderate spinal cord injury. This work uses an air blast cannon system (i.e. a modified paintball gun) that was designed to induce a non-invasive percussive injury. Our goal is to produce diffuse axonal injury, such as would occur when the spinal cord is stretched or deformed but the vertebral column remains intact, and thereby to mimic the damagethat frequently accompanies motor vehicle accidents, falls, and sports injuries. The injury is being evaluated using both behavioral assays and immunofluorescent labeling to reveal effects on specific neuronal tracts. Future studies will elucidate the cellular and molecular mechanisms underlying the injury and assess possible therapies.
Tony Reiner, Ph.D.
The work in this laboratory focuses on the organization, function, and diseases of the basal ganglia and visual system, and on the evolution and fundamental organization of the vertebrate forebrain.
With respect to basal ganglia organization and function, we are exploring the neural substrate by which different types of cortical and basal ganglia neurons differ in their role in movement control. We are particularly interested in whether different types of cortical neurons communicate with different types of basal ganglia neurons to mediate different aspects of movement control. To address such issues, we use LM and EM labeling methods (pathway tracing, immunohistochemistry and in situ hybridization) in various combinations to determine the neurotransmitters used by specific cells types, the inputs and outputs of those cells types, and the receptor mechanisms involved in those inputs and outputs.
In our work on basal ganglia disease, we study the means by which the gene mutation in Huntington′s disease leads to selective destruction of neurons in the striatal part of the basal ganglia. We use experimental animal models and genetically engineered mice, and we have been particularly interested in the possibility that the mutation perturbs the function of cortical neurons projecting to striatum so as to render them injurious to their target striatal neurons. This injury process could involve excess glutamate release from corticostriatal terminals or diminished production by corticostriatal neurons of neurotrophic factors needed for survival by striatal neurons.
In our work on the visual system, we are interested in the neural mechanisms by which blood flow in the choroid of the eye is adaptively controlled according to retinal need and in the role disturbances in such neural control may play in age-related decline in retinal function.
Finally, we have a longstanding interest in the evolution of the cerebral cortex, basal ganglia, and thalamus, and in how these structures differ among birds, reptiles and mammals. In our studies, we use neurochemistry, hodology and the localization of developmentally regulated genes to characterize the organization of these regions and ascertain the course evolution has taken.
Kathryn A. McVicar, M.D.
Translational Research in Autism
The Pediatric Neuroscience Institute is conducting several related studies in autism. A student choosing to work with us will be exposed to translational research and able to participate in both clinical and biomedical research.
Specific clinical research skills to be addressed include the application of HIPPA rules in research, the informed consent process, with specific emphasis on differences between pediatric and adult populations, the recruitment and consenting of study and control patients and the appropriate techniques for data collection and recording.
Specific biomedical laboratory exposure will include understanding that Drosophila melanogaster (fly) proteomic profiling can be used to identify molecular and genetic pathways in human systems. The isolation of proteins from these human sera samples will be used to isolate monoclonal antibodies generated against total fly brain homogenate. It will then be seen which of the proteins collected cross react with human neuronal tissue. Once identified, these proteins will be used to identify particular subsets of neurons in the human nervous system that may be involved in the syndrome of autism.
Lawrence T. Reiter, Ph.D.
My laboratory utilizes the powerful genetic model organism Drosophila melanogaster (fruit flies) to investigate the functions of genes involved in human neurological diseases. Our main focus is the study of genes related to Angelman syndrome and autism spectrum disorders. These disorders are interrelated at the molecular level and one of the goals of our laboratory is to identify genes and proteins regulated by one or more of the proteins that can cause and autism phenotype. In addition, approximately 3-5 % of all autism cases result from maternally derived duplications of the region containing the gene that causes AS, UBE3A. Mutations in the protein targets of the ubiquitin ligase UBE3A may therefore account for a significant percentage of idiopathic autism cases as well.
In our laboratory we utilize Drosophila specific genetic techniques that allow us to generate artificially high levels of normal and mutant fly Dube3a proteins in fly heads. Wild type, dominant negative and epitope tagged forms of ube3a are over-expressed in the brains of flies using the GAL4/UAS system in order to increase or decrease the levels of Dube3a protein targets. We have now identified 50 of these potential Dube3a regulated proteins (Jensen et al. PLoS One. 2013 Apr 23;8(4):e61952) and are actively validating these interactions using whole genome molecular methods (genomics), genetic suppressor/enhancer screens, immunostaining in fly neurons (immunoflourescence), and changes in synaptic function and stability at the fly neuromuscular junction (electrophysiology). Using these methodologies in flies we have identified Dube3a regulation of the actin cytoskeleton (Reiter et al. Hum Mol Genet. 2006 Sep 15;15(18):2825-35) as well as the synthesis of monoamines (Ferdousy et al. Neurobiol Dis. 2011 Mar;41(3):669-77) and ion transport across axonal membranes (Jensen et al. PLoS One. 2013 Apr 23;8(4):e61952).
We have also been doing in depth phenotypic and molecular analysis of individuals with interstitial duplication 15q autism. Since 2007 we have been collecting a variety of language, neuropsychiatric, neurological and gene expression data from subjects with interstitial 15q chromosomal duplications and just recently published our clinical findings (Urraca et al. 2013 Autism Res. 2013 Aug;6(4):268-79). We hope that our basic research into the functional targets of UBE3A will lead to a better understanding of the phenotypes in this particular autism population where the UBE3A gene is duplicated, and presumably expressed at higher levels than in unaffected individuals. For more information on our clinical study see http://www.idic15.org/Dr-Reiter.html. As an extension of this work which bridges the gap between basic and clinical research, we recently began an NIH funded study to generate dental pulp derived neruons from individuals with either the Angelman syndrome deletion in this region or a duplication of this region on chromosome 15q causing autism. We hope that these patient-derive neuronal cultures will allow us to perform more in depth molecular and electrophysiological analysis of both conditions in the near future. For more information on the dental pulp stem cell study please see http://tinyurl.com/88f688l.
Alex Dopico, M.D., Ph.D.
My laboratory is interested in determining the mechanism of action of small amphiphilic compounds on ion channels from excitable cells. One of these amphiphiles is alcohol, the most widely used and abused drug. Some others are physiological modulators, such as bile acids and neurosteroids. Our current research is focused on two projects dealing with large conductance, Ca++-activated K+ (BK) channels. These channel proteins have been demonstrated to be involved in both controlling central neuron excitability and regulating arterial smooth muscle tone. Project 1: To determine the molecular basis for differential actions of alcohol on BK channels from mammalian brain vs. arterial smooth muscle, including modulation of drug action by membrane lipids. Project 2: To determine the structural requirements (both in the amphiphile molecule and the ion channel protein) for the modulation of arterial muscle BK channels by bile acids.
For these studies we combine electrophysiological and molecular biology techniques. Ion channel responses to drug exposure are evaluated in: 1) freshly isolated cells, where we study drug modification of channel behavior in the native environment of the channel protein; 2) isolated patches of cell membrane, where we can address the differential role of different membrane-bound vs. cytosolic second messengers in drug action; 3) artificial bilayers of controlled lipid composition, where we can determine the modulatory role of membrane lipids in drug action.
Ion channel isoforms from relevant tissue are identified. Following mRNA isolation and cloning, channel subunits of known sequence are expressed in heterologous systems such as Xenopus oocytes or HEK-293 cells. Then, we can determine the role of channel subunit composition in drug action by studying drug effects on ion channel complexes that differ in pore-forming and/or modulatory subunit composition. In addition, differential responses to a drug by channels that differ in a given region of a subunit, when studied in the same proteolipid environment, allow us to postulate sites in that subunit for drug recognition. This is probed by studying drug action on expressed channel proteins that include mutations in the postulated region(s).
My laboratory is interested in determining the molecular mechanism of action of alcohol and other small amphiphiles on ion channel proteins from the brain and arterial vessels. To determine the recognition sites for alcohol in these proteins and how alcohol modifies protein function upon interaction with these sites, will provide critical information for understanding how the drug interacts with its targets and, eventually, lead to the design of clinically useful agents to treat conditions associated with alcohol intake.
Kafait U. Malik, Ph.D., D. Sc.
The overall objective of our research is to elucidate the cellular and molecular signal transduction mechanisms of growth factors, circulating hormones including angiotensin II (Ang II) and locally generated autacoids (eicosanoids) and adrenergic transmitter norepinephrine (NE) in the regulation of cardiovascular function in health and in the development of hypertension and vasculopathy associated with restenosis, atherosclerosis and diabetes. Our studies should further our knowledge of the neuro-humoral mechanisms that regulate vascular function and its alteration in vascular diseases. Moreover, these studies should allow formulating rational approaches for the development of novel therapeutic agents for the treatment of hypertension, arteriosclerosis and restenosis.
We use isolated cultured vascular smooth muscle and endothelial cells, isolated perfused organs (heart, kidney and blood vessels), wire myogrph for measuring vascular reactivity models of hypertension (Ang II- and DOCA-Salt and SHR), balloon injured carotid artery and now we are also transgenic animals for our studies. The laboratory techniques also include the use of HPLC-GC-Mass spectrometric Analysis of Eicosanoids, SDA-PAGE and Western blot analysis, DNA and RNA isolation, purification and quantitation, PCR, RT-PCR, Q-PCR, DNA transfection in cells Plasmid preparation, restriction fragment mapping, Construction of siRNA of various signal molecules, Transfection of reporter vectors as well as over-expression of constitutively active or dominant negative proteins, Co-immunoprecipitation and co-localization techniques, con-focal microscopy, site direct mutagenesis Molecular imaging of protein interactions Immunoassays and protein analysis, insertion of miRNA into adeno-, lenti- and adeno-associated viral vectors and preparation of viruses for transfection in cultured cells and for in vivo use. The signaling molecules studied by ELISA, in vitro kinase assay and Proteomics include, RasGTPas, ERK1/2, MEK, Raf, p38MAPK, c-JNK, PI3 kinase, Akt, JAK-STA, Pyk-2, c-Src, Syk and EGF.
Kazuko Sakata, Ph.D.
Current projects in my laboratory focus on studying the roles of gene regulation of brain-derived neurotrophic factor (BDNF) in major depression. BDNF is a major neuronal growth factor in the brain that promotes neuronal development and synaptic plasticity. BDNF has been suggested to be involved in both pathophysiology of depression and action of antidepressants; BDNF expression is decreased in the serum, hippocampus and prefrontal cortex (PFC) of patients with major depression, which can be reversed by chronic, but not acute, antidepressant treatments. However, the underlying mechanisms of how decreased BDNF levels lead to depression and of how increased BDNF levels provide antidepressant effects remain to be understood. We are trying to address these underlying mechanisms by focusing on BDNF promoters using promoter specific mutant mice. Our research goal is to find out how promoter-specific gene regulation of BDNF is involved in pathogenesis of depression/depression-like behavior and recovery from mood disorders. We use a multidisciplinary approach from gene to behavior with genetic, molecular and biochemical, electrophysiological, and behavioral techniques. While major depression is the leading disease burden in industrialized countries including the North America, we believe that understanding the underlying mechanisms will advance the future therapy for depression.
Fu-Ming Zhou, Ph.D.
Dr. Zhou currently conducts a multidisciplinary research program designed to determine the molecular, cellular and neuropharmacological mechanisms of the brain monoamine systems. Particular attention is being paid to the contributions of these monoamine systems to neuropsychiatric disorders such as Parkinson’s disease, depression, schizophrenia, drug abuse, and attention deficit hyperactivity disorder (ADHD). We use rodents as our experimental animals. Mutant mice are also used.
Several techniques are used in the laboratory:
- Electrophysiology-patch clamp
- Single cell RT-PCR (in combination with patch clamp)
- Electrochemistry (fast cyclic voltammetry at the carbon fiber microelectrode; HPLC)
Dr. Zhou's research is funded by R01 grants from the National Institute on Drug Abuse and National Institute of Mental Health and grants from private foundations.
Ioannis Dragatsis, Ph.D.
Project 1 Title: Analysis of a mouse model for Familial Dysautonomia
Familial Dysautonomia (FD) is an autosomal recessive disorder that affects 1/3,600 live births in the Ashkenazi Jewish population, leading to death before the age of 40. The disease is characterized by progressive degeneration of the sensory and autonomic nervous system. Despite the identification of the gene that causes FD (Ikbkap) and recent medical advances, no cure is available. We have generated a mouse model recapitulating the phenotypic features of the disease and our goal is to elucidate the mechanisms that lead to neuronal degeneration in FD and to test therapeutic strategies.
Project 2 Title: Analysis of the function(s) of huntingtin
Huntington's disease (HD) is an autosomal dominant disorder that affects 1 in 10,000 individuals. HD is characterized by chorea, rigidity and progressive dementia. Symptoms usually begin between the ages of 35 and 50 years, with death typically following 15 to 20 years later. HD is caused by the expansion of an unstable stretch of CAG triplet repeats within the coding region of the HD gene. Moreover the protein encoded by the HD gene, huntingtin, is a novel protein of unknown function.
We are using the mouse as a model organism. Inactivation of the mouse homologue of the HD gene results in embryonic lethality demonstrating that huntingtin is essential for early embryonic development. Conditional inactivation of the gene at later stages results in progressive neurodegeneration in the adult mouse, suggesting that huntingtin is also essential for neuronal survival.
Charles W. Leffler, Ph.D.
We employ a multitude of techniques from intravital microscopic studies of cerebral circulation in vivo, to subcellular imaging, molecular-cellular approaches, biochemistry and even chemistry. So it completely depends on the student what kinds of techniques are involved. Most tend to want to do in vivo cranial window studies. I could give him something like this for our interests if that's what you are looking for.
Research in the laboratory concentrates on control of cerebral circulation. The primary focus of this research involves autocrine/paracrine control of the newborn cerebral microvasculature during physiologically stressful and pathological situations, and the cellular mechanisms involved in such control. We investigate autocrine and paracrine communication within the vessel wall, with specific current focus on the novel gasotransmitter, carbon monoxide.
Kristen O'Connell, Ph.D.
In most adult humans, weight gain is typically a result of overconsumption and is associated with diseases such as Type 2 Diabetes, gout, cardiovascular disease, and some cancers. However, it is increasingly clear that obesity is also a neurological disorder: excessive food intake induces persistent changes in the neural circuitry regulating food intake and appetite in the brain of overweight and obese individuals that make it difficult to lose weight. Obesity-induced changes in the brain occur before significant increases in body weight, suggesting that these neural changes precede the development of obesity. Our focus is on understanding how the neurons that comprise this circuit are rewired in response to dietary interventions such as food deprivation and diet-induced obesity. We hypothesize that obesity causes activation of hunger-inducing circuits in the hypothalamus, thereby inducing a persistent sensation of hunger, even when there is no physiological need for food. Understanding how these circuits function in both lean and obese animals may lead to better therapeutic approaches for treating obesity.
We use a variety of transgenic mice that express green fluorescent protein (GFP) in defined neuronal populations as well as mice expressing the light-activated ion channel ChR2 in GABAergic neurons, allowing light-dependent control of neural circuits. We primarily use chronic feeding of high-fat (Western) diets to induce obesity in mice.
Techniques used in the lab include:
- Brain slice electrophysiology
- Optogenetic control of neuronal activity
- Multi-photon microscopy and immunohistochemistry
- Behavioral assays (food-seeking behaviors, daily food intake and body weight measurements, administration of obesogenic diets, etc.)
University of Tennessee Health Science Center
875 Monroe Ave, Suite 426
Memphis, TN 38163
Phone: (901) 448-5960
Fax: (901) 448-4685
426 Wittenborg Anatomy Building
William E. Armstrong, PhD
Anton J. Reiner, PhD
Brandy Fleming, MS