Prof. Kent Dunlap (LSC 245) - Electrocommunication & Physiology of Electric Fish

I examine the influence of social interaction on the brain structure and communication of electric fish.  South American weakly electric fish are nocturnally active and live in muddy waters of the Amazon River basin. They use their electric discharges both for locating objects in the environment and for communicating with each other.

These fish have a remarkable ability to generate new cells in the brain during adulthood, at about 100 times the rate of adult mammals. Research by Trinity students showed that this production of new cells is influenced by social interaction. Pairing fish with another fish increases the production of cells in a brain region that controls electrocommunication behavior.

In our present research, we address three main questions: 1) What specific component of social interaction is effective in stimulating changes in brain cell production?  2) Do the new cells that are produced contribute to changes in electrocommunication behavior?  3) How do these newborn cells differentiate into mature cells? This research involves examining the expression of certain molecules in the brain using antibodies and florescent microscopy.

In a separate project, students examine electrocommunication behavior between different species of electric fish and conduct experiments to determine the sensory pathways involved in this interspecific electrocommunication. This research involves observing fish as they interact and stimulating fish with artificial electrocommunication signals.

back to top 

Prof. Robert Fleming (LSC 238) - Cell signaling and Developmental Controls

As an organism develops, cells differentiate into specialized cell types and adopt specific patterns of gene expression.  Using molecular and genetic techniques in the fruit fly, my laboratory is attempting to understand the mechanisms that control cell differentiation in embryonic and adult tissues.  The focus of our work is on the Serrate gene, which encodes an evolutionarily conserved  transmembrane protein capable of physically binding to and activating the NOTCH receptor gene at the same site where another ligand, that of the Delta locus, also binds. During the formation of the adult wing blade, the wing margin is established via NOTCH activation using both the SERRATE and DELTA ligands.  Our studies indicate that NOTCH responds differentially to these respective ligands, eliciting compartment-specific responses in gene regulation.  We have utilized site-specific mutagenesis to define domains of SERRATE that confer receptor-response specificity. Our goal is to understand how identified molecular and genetic interactions control cellular differentiation in specific cell types, and to locate and characterize other genes involved in this process.

Another area of interest in our laboratory is nuclear import.  Molecules enter and exit the eukaryotic nucleus in a regulated manner involving selective transport by proteins known as importins.  We study the importin-alpha  gene family which consists of three members: imp-alpha1, imp-alpha2, and imp-alpha3. Our findings indicate that although all three can perform the same function in some cellular processes, each is likely to have specific individual functions as well. Our studies are focussed on determining what the specific functions are for each of these proteins. In our research, we employ a battery of techniques from genetic selection through in vitro mutagenesis and germline microinjection to specifically address structure and function relationships among interacting genes.

Prof. Lisa-Anne Foster (LSC 236) - Molecular Mechanisms of Host-Parasite Interactions
Bacteria are considered to be relatively simple organisms by most. However, these microscopic beings possess elegant systems of turning protein synthesis on and off in response to environmental changes. When infecting a host, bacteria encounter important cues such as temperature and nutrient availability which help the microbes orient themselves within the host. The host is often a hostile environment and bacteria must compete for essential nutrients, as a result many bacteria begin to synthesize an entire array of new proteins once inside the host in order to obtain limiting nutrients. I am specifically interested in understanding how bacteria meet their need for iron while living inside a host. In many organisms a novel set of proteins is made during infection allowing them to acquire iron from the host or to synthesize new proteins related to iron use or storage. This production of new proteins is regulated at the transcriptional level and very often affects the proteins which are expressed on the outer surface of the bacteria, which may be important in the design of new vaccines. In my lab, we are examining the ability of two different microbes to meet their need for iron during infection.

Bordetella bronchiseptica is a bacterium causing animal disease which is closely related to the human pathogen, B. pertussis (the etiologically agent of whooping cough). This organism lives in the upper respiratory tract of a mammalian host where it likely competes for lactoferrin and heme as sources of iron. We are currently studying the heme biosynthetic pathway in this organism. We have cloned the hemA gene, the first committed step in heme biosynthesis and are in the process of obtaining sequence data. Our goal is to understand what environmental signals control the synthesis of heme in this organism. Projects available for students include:

• cloning the entire set of genes involved in heme biosynthesis 
• constructing a hemA mutant of B. bronchiseptica 
• constructing specialized strains of B. bronchiseptica to measure hemA production under various environmental conditions 

Histoplasma capsulatum is a fungal pathogen which resides inside of macrophages (the immune cell charged with destroying foreign invaders) during infection. We have obtained strong evidence that this organism possess a cell surface receptor for binding and internalizing heme from the macrophage during infection. We are using the following strategies to identify this heme-binding protein:

• chemi-luminescent assay to detect heme-binding to H. capsulatum surface proteins 
• analysis of mRNA to determine the specific genes expressed during iron-starvation 
• the quantitation of heme available inside of macrophages during H. capsulatum infection 

Most of the projects in my lab employ modern molecular biology. We are engaged in cloning and sequence analysis of genes, construction of new recombinant bacterial strains as well as studying the physiology of the various mutants we construct. 
 

Prof. Hebe Guardiola-Diaz (LSC 309) - Biochemistry and Molecular Biology of Nuclear Receptors in the Nervous System

Neuronal development, differentiation, communication, plasticity and programmed death depend on changes in gene expression. Neurons express a number of nuclear receptors that can act as ligand-activated transcription factors and orchestrate important transcriptional changes that satisfy demands for new proteins that directly play various roles in nerve cells. One such nuclear receptor, PPARd, is expressed in developing and adult nervous tissue. One of the questions we are focusing on is the elucidation of the role of this receptor in neuronal development. To answer this question we are taking several complimentary approaches:

• Analysis of the biochemical and morphological consequences of PPARd expression in cultured cells.
• Study of the transcriptional regulation of the PPARd gene and search for correlations with cellular developmental stage.
• Identification of novel and/or known protein partners for PPARd in developing human brain.
• Identification of novel nuclear receptors in nervous tissue. In addition I am interested in establishing a high throughput fluorescence-based assay to identify new molecules that can induce the neuronal phenotype. This long-term project will combine biochemical and molecular genetics and may open up new areas of interest and investigation.

Prof. Joan Morrison (LSC 230) - Conservation Biology

My research program entails studying the population biology, habitat associations, and community structure of birds living in human-impacted landscapes.  Questions focus on the population structure of small and isolated populations and the role that spatial variation in habitat and resources plays in determining patterns of reproduction, survival, and movement.  On-going research projects include 1) using radiotelemetry to study Red-tailed Hawks living in Hartford, and 2) monitoring an isolated population of the threatened Crested Caracara living in Florida.  Two students and I recently completed an extensive analysis of the caracara's breeding season diet and examined weather factors potentially influencing reproduction in the Florida population.  I have also examined the structure of avian communities in urban parks in Hartford and how these communities change throughout the year.  The overall goal of this project is to understand the role these urban green spaces play in the conservation of native birds in Connecticut.  I conduct monthly monitoring of birds at the Trinity College Field Station (TCFS) in Ashford, CT.  TCFS is also a MAPS site, so during the summer, my students and I mist net and band birds there, contributing to this nationwide avian monitoring database.

Conservation education plays a major role in all my research.  Scientists must improve their communication skills with people outside their academic and peer groups, therefore I require all my students to interact in some way, regarding science or conservation, with people outside the Trinity campus.  We frequently conduct banding sessions at local elementary and middle schools.