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Research Interests

Department of Biology

Location: M-804, Phone: 718-488-1208

Denise Chung, Ph.D.

Denise Chung, Ph.D.
Professor
Research: Biochemistry
Education: Ph.D., Biochemistry, New York University, New York, NY
Phone: 718-246-6412; Fax: 718-488-1465; E-mail: denise.chung@liu.edu

Dr. Chung’s research focus on the intra-cellular growth pathways which can lead to the formation of cancerous cells, especially with regard to pancreatic and intestinal cancers. Specifically, the role of proteins, such as oncogenic Ras-p21are studied through the examination of de novo phosphorilation pathways in the mature oocytes of Xenopus Laeves frogs. The roles of specific messenger molecules in these pathways are elucidated and the effects of blocking the pathways at various stages are studied.

Anthony L. DePass, Ph.D.

Anthony L. DePass, Ph.D.
Associtate Professor
Co-Director of the Multimedia and Interactive Learning (MIL) Project
Research: Cell Biology
Education: Ph.D., Molecular and Cellular Biology, 1999, University of Massachusetts, Amherst, MA
Webpage: http://myweb.brooklyn.liu.edu/adepass/
Phone: 718-488-1487; Fax: 718-488-1465; E-mail: adepass@liu.edu

Dr. DePass concentrated his research on the utilization of ratioimaging to elucidate temporal and spatial characteristics of intracellular Ca2+ release in response to second messengers such as IP3, and cyclic ADP Ribose, a metabolic product of the enzymatic conversion of NAD+ by ADP Ribosyl cyclase. Additionally, he has also used microinjection experiments with synthetic analogs of IP3 to determine the metabolic fate of IP3 after the activation of its receptor that facilitates the release of Ca2+ from intracellular stores. Presently, students in Dr. DePass’ lab are working on a project aimed at cloning the IP3 receptor in plants. The animal receptor has been cloned but a survey of the sequenced genome of Arabidopsis thalia shows no identity with the animal sequence at the amino acid level. Using algorithms that determine conservation based on the location of specific amino acids in a crystallized segment of the mouse receptor that contains the IP3 binding site in addition to analysis of the sequences of the five animal genes, it has been demonstrated that a high correlation exists at two sites of conservation indices and close proximity (within 5 angstroms) to the 4, and 5 phosphates of the ligand. Dr. DePass’ previously published work demonstrated that the presence of the 5-phosphate in IP3 was critical for receptor activation. The residues that were determined to be in very close proximity to the 5-phoaphate closely correlated with high conservation indices and were used to design degenerate PCR primers that account for amino acid substitutions that create a loss of primary sequence identity but preserve functionality.

Carole Griffiths, Ph.D.

Carole Griffiths, Ph.D.
Associate Professor
Research: Evolution, Ornithology
Education: Ph.D., Evolution, Ornithology, CUNY, City College, New York, NY
Phone: 718-780-4164; Fax: 718-488-1465; E-mail: carol.griffiths@liu.edu

My research uses phylogenetics to investigate topics in evolutionary biology, including molecular evolution and speciation.

Within the area of molecular evolution, I am particularly interested in protein structure and the correlation of protein structure and the evolution of protein-coding genes. Knowledge of protein structure, and the correlation of amino acid variation with structural features, provides information about rates of variation and of co-variation among codons in the gene coding for that protein. This information can be useful for developing models to use in phylogenetic inference and for elucidating details of the evolution of the structure of that protein.

The proteins that I am examining are in the family of G-protein coupled receptors (GPCR). I have collaborated with Dr. Lorraine Marsh on a study of rhodopsin evolution within vertebrates. We are preparing a manuscript describing the results of our research. In addition, I have two students, including one Rise student, examining evolution in two other GPCRs, the melatonin receptor and the Follicle-Stimulating Hormone (FSH) receptor.

The second broad area of interest is speciation. This process occurs when separate populations within a species have diverged sufficiently from each other. To investigate this process, I am examining genetic variation among populations of two different bird species, the American Kestrel and the Red-shouldered Hawk. For the first study, I am collaborating with Dr. J. Parrish of the University of Georgia. Two students, including one RISE student, are working on this study. My collaborator in the second study is Ms. Sara Chambers.

Janet Haynes, Ph.D.

Janet Haynes, Ph.D.
Associate Professor
Research: Experimental Hematology
Education: Ph.D., Physiology,New York University, New York, NY
Phone: 718-488-3348; Fax: 718-488-1465; E-mail: janet.haynes@liu.edu

Dong H. Kwon, Ph.D.

Dong H. Kwon, Ph.D.
Assistant Professor
Research: Molecular Mechanisms of Antibiotic susceptibility and resistance
Education: Ph.D., Microbial Genetics & Biochemistry, Georgia State University, Atlanta, GA
Phone: 718-488-4098; Fax: 718-488-1465; E-mail: dong.kwon@liu.edu

My research interest has centered in pharmaceutical biotechnology focusing on molecular details of drug resistance mechanisms, finding new drug targets (or a new drug), and a novel strategy to treat drug resistant (or susceptible) bacterial pathogens.

I have been studying bacterial pathogen of Helicobacter pylori (H. pylori), which is a Gram-negative bacterium infecting more than 50% of the human population. H. pylori infection is associated with peptic ulcer disease, gastric lymphoma, and gastric cancer. Current H. pylori eradication therapies consisting amoxicillin, clarithromycin, metronidazole, or tetracycline are successful in the range of 60 to 80%. Failure of treatment is mostly due to the presence of antibiotic resistant H. pylori.

My work was devoted to understanding the molecular details of resistance to these antibiotics. The molecular bases of resistance to these antibiotics relate to chromosomal mutations on the antibiotic-target genes, (e.g., a gene encoding penicillin-binding protein [pbp-1A] for amoxicillin, genes encoding 23S rRNA for clarithromycin, genes encoding 16S rRNA for tetracycline, and inactivation of a gene encoding metronidazole nitroreductase [rdxA] for metronidazole). My research interest has moved to find new drug targets (or a new drug) to treat the drug resistant bacterial pathogens. A whole genome microarray analysis obtained from H. pylori showed that the rdxA gene was primarily down-regulated and inactivated in the development of metronidazole resistance. Based on the genome analyses, down-regulation of the rdxA gene is associated with up-regulation of a two-component signal transduction system (HP0164/HP1043) in response to metronidazole stress. Current research is focused on testing the roles of the HP0164 and HP1043 in metronidazole susceptibility.

I also have been studying bacterial pathogen of Pseudomonas aeruginosa (P. aeruginosa), which is a Gram-negative predominant respiratory pathogen in patients with cystic fibrosis and the third leading cause of severe hospital-acquired infections. The treatment of P. aeruginosa is extremely difficult due to intrinsic and acquired multidrug resistance.

The project for P. aeruginosa is also based on genome analyses obtained from P. aeruginosa grown with polyamines, a group of ubiquitous and essential polycationic compounds in all living organisms. Genome analyses showed that polyamines sensitize resistant P. aeruginosa to a variety of beta-lactam antibiotics. The sensitization-effect of polyamines is also applicable to other human pathogens including E. coli, S. typhimurium, and even methicillin-resistant Staphylococcus aureus. Based on this finding, a patent has been filed in USA (U.S. Patent No. 11/420,671 entitled "Use of Polyamines with Antibiotics"), which holds a great potential in clinical applications. I hypothesize that the polyamines enhance binding-capability of beta-lactam antibiotics to the penicillin-binding proteins (a target protein for beta-lactams) from the beta-lactam resistant strains and/or the polyamines are associated with down-regulation of genes encoding the penicillin-binding proteins. The hypothesis is currently being tested by measurement of affinities between radiolabeled-penicillin and the penicillin-binding proteins in the presence or absence of polyamines employing fluorography and spectrometry analyses.

Timothy W. Leslie, Ph.D.

Assistant Professor
Research: Ecology, Entomology
Education: Ph.D., Entomology, Pennsylvania State University
Phone: 718-780-4104; Fax: 718-488-1465; E-mail: timothy.leslie@liu.edu

Human activities permeate every corner of the globe, often converting large areas of native habitat into urban centers or agricultural fields. How these changes influence biodiversity and even our own survival is a major issue in ecological research. As an insect ecologist, my research program centers on the following question: How do these anthropogenic activities influence insect populations, communities, and ultimately biodiversity and ecosystem function?

Due to their ubiquity and large numbers, insects and related arthropods can serve as an excellent tool to measure environmental response to any number of external factors. Additionally, many insects are the primary drivers of a wide array of ecosystem services (e.g., pollination, biological control), and wise stewardship of insect diversity can be a means of managing ecosystems toward sustainability. Thus, one goal of my research is to identify management tools or environmental variables that can support both biodiversity conservation and ecosystem function. I also conduct research on economically important pest species. This includes explaining and modeling patterns in their population dynamics (often spatially explicit) to best identify pest management options that are economically feasible and ecologically sustainable.

My research is field-based and is conducted in a range of managed ecosystems, including agricultural lands and highly urbanized landscapes, which are characterized by habitat fragmentation and high levels of external inputs. Robust sampling programs, high levels of taxonomic resolution, and creative statistical approaches are used to best identify patterns in insect diversity and dynamics, and inform sound management decisions.

Lorraine Marsh, Ph.D.

Lorraine Marsh, Ph.D.
Associate Professor
Research: Signal Transduction
Education: Ph.D., MIT, Boston, Massachusetts
Phone: 718-488-1437; Fax: 718-488-1465; E-mail: lorraine.marsh@liu.edu

Research in my laboratory is focused specifically on G protein-coupled receptors (GPCRs) and protein structural bioinformatics and evolution, in general. GPCRs are a homologous but diverse family of receptors (there are about 800 different GPCRs in humans), which are the targets for almost 40% of all drugs. (I have studied GPCRs of one type or another for almost 25 years.) GPCRs are membrane proteins that act by binding ligands on the outer face of the membrane and transmitting a conformational change to the inner face of the membrane. Currently, a variety of different projects related to GPCRs and other proteins are under investigation in my lab. In a recently published study, I have shown that amino acid changes tend to be spatially correlated in GPCRs and in definite residues of the receptor involved in transmitting the signal. This paper introduced concepts that need to be generalized by analyzing a wider variety of proteins, which is an on-going pursuit in my laboratory. I also have an interest in the poorly understood (GPCR) trace amine receptors and have been performing molecular dynamics, binding energy decomposition and docking studies to determine the mechanism by which they bind rather featureless ligands such as phenylethylamine. Thus far, it seems that one part (the amino group) of the ligand binds trace amine receptors with high affinity, while another part of the ligand (the ring) may play a role in receptor activation. A final project, just starting, is an effort to map determinants of ligand specificity for GPCRs. Receptors with ligand specificity for epinephrine or for adenosine will be compared using new methods being developed that may be capable of detecting sites conferring selection for ligand specificity even if these sites act at a distance. These projects are united in the goal of understanding GPCR functioning as a receptor. More broadly, my interests lie in understanding how proteins function and change given constraints of structure.

Joseph Morin, Ph.D.

Joseph Morin, Ph.D.
Chair & Associate Professor
Research: Molecular Biology
Education: Ph.D., Molecular Biology, University of Wisconsin - Madison, Madison, Wisconsin
Phone: 718-246-6418; Fax: 718-488-1465; E-mail: joseph.morin@liu.edu

Ximara Peckham, M.D.

Ximara Peckham, M.D.
Visiting Professor
Research: Physician & Surgeon
Education: M.D. Caloas University, Manizales, Colombia
Phone: 718-246-6412; Fax: 718-488-1465; E-mail: ximara.peckham@liu.edu

Adverse events to vaccines. Currently working on a research project of Safety of Live vaccines in Children with DiGeorge Syndrome at Columbia University.

Jose G. Tello, Ph.D.

Jose G. Tello, Ph.D.
Assistant Professor
Research: Evolutionary Biology
Webpage: http://myweb.brooklyn.liu.edu/jtello
Education: Ph.D., Ecology and Evolution, University of Illinois, Chicago, IL
Phone: 718-488-1470; Fax: 718-488-1465; E-mail: jose.tello@liu.edu

My research program focuses on the systematics, evolution, and biogeography of birds. I study relationships across a broad hierarchy of birds from entire families to within species. A fundamental goal is to understand the origin of biodiversity and the biogeographic history of the Neotropical region including macroevolutionary patterns such as behavioral, ecological, and morphological diversification.