CURRENTRESEARCH IN BIOLOGY

One of the opportunities available to students in Biology at Trinity is a direct involvement in research. Some students already may have definite ideas regarding research proposals, while others may have only general notions of the kind of problems that seem interesting. In either case, the specific problem should be worked out with a member of the faculty during the semester before initiation of the project. If you are contemplating research, discuss it with the faculty member whose programs fit your interests; the research projects of the faculty are summarized below. Also keep in mind that some students engage in research programs in local hospital laboratories under the joint supervision of the Biology Department and the extramural laboratory. Please direct inquiries about these options to the Chair of Biology.

Prof. Kathleen Archer (LSC 344) - The biology of sea slug - chloroplast relationships

One of the most fascinating areas of biology is that of symbiotic mutualisms - where two different species live closely together to the benefit of both. We are interested in an unusual relationship between the marine sea slug Elysia and the algae on which it feeds. Unlike land slugs, marine sea slugs are beautiful creatures - highly ornamented and brightly colored. The species Elysia chlorotica, for example, is an intense, rich, green color, and it turns out this pigmentation comes from chloroplasts ingested while the animal feeds on the alga Vaucheria. The chloroplasts are taken up by cells lining the digestive tract, and there they continue to photosynthesize, providing food for the slug. In fact, if the slugs are given good light they can go without food for many months, relying completely on the chloroplasts for energy. This is a highly unusual twist on symbiosis, as the relationship is not between two different organisms but between an organism and an organelle.

We are interested in how the sea slug can keep chloroplasts alive and functional outside their native algal cells, and whether the slug behavior is adapted to benefit its symbiont. For example, do the sea slugs seek out the optimum light intensities for photosynthesis? Do they move to areas where light wavelengths are best suited for chloroplasts? Do they seek shade when light is too strong? We are also interested in the unique properties of the algal chloroplasts the slugs feed on. The species used by the slugs are well-known for their extremely robust chloroplasts, but know one knows what makes them so tough. How do they avoid getting digested - do they inhibit digestive enzymes, or are they just highly resistant? Do they have physical structures that help them stay intact under such damaging conditions as the slug digestive tract? We anticipate that electron microscopy studies, tests of resistance to digestive enzymes and other treatments will reveal much about what makes this unusual relationship possible.

Prof. Daniel Blackburn (LSC 247) - Functional Morphology & Reproductive Biology of Vertebrates
 
My current research concentrates on the structure, function, and evolution of reproductive specializations in reptiles ö particularly features associated with the reproductive pattern of viviparity (live-bearing reproduction).  This work draws heavily on microscopic anatomy, and students interested in working with me ideally should gain experience with electron microscopy, during or (even better) before their senior year.  Our excellent new EM facilities in the LSC and McCook, and my Fall course Biology 350, offer a wonderful opportunity for Trinity students to learn techniques of immense value to biologists.  I do have an option for students who wish to focus their attention at the level of light microscopy.  Research of several of my recent students has resulted in collaborative research publications or presentations at scientific meetings.
 
  • Placental formation and fetal nutrition in live-bearing squamates.
    • In viviparous lizards and snakes, embryos develop inside the pregnant female, and are sustained by means of placental organs. My main research interest is in understanding the structure, function, and evolution of these placentas. Our current work is focusing on how anatomical characteristics of the placental membranes of viviparous snakes enhance provision of oxygen, water, and nutrients to the fetus during the three-month gestation period.  This work involves examination of the cytology and development of the uterus and extraembryonic membranes, using light and electron microscopy.
  • Developmental anatomy of extraembryonic membranes of oviparous reptiles and birds
    • During development, vertebrate eggs are sustained by membranes that provide for the respiratory and nutritional needs of the developing embryos.  These membranes contribute to the placentas of viviparous species.  In reptiles and birds, very little is known about the structural composition of these membranes, and how they develop and function.  Our current work on corn snakes (Elaphe) uses light and electron microscopy to study the development and cytology of these membranes.  In the near future, we shall build on recent work done in my lab on quail egg development, as a means of understanding the structure, function, and evolution of these membranes in birds.

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

    I examine sensory mechanisms, hormonal regulation and evolution of communication behavior in 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. Males and females give off distinct electric signals during courtship and aggression, and these sex differences are generated through the actions of steroid hormones such as testosterone and estrogen.

    My present research has three components. First, I try to decode their "electric language" used in social interaction by observing fish in different behavioral contexts. I modify specific sensory stimuli and examine how the fish's electrical signals change. Second, through immunocytochemical analysis of their brains, I trace which neural pathways are responsive to steroid hormones and how these pathways are activated in a context-specific manner. Finally, I compare hormonal regulation of the electrocommunication system in various species to address how the endocrine system evolves to generate a diversity of sex-specific electrocommunication behaviors.

    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:

    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: 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:

    Prof. Joan Morrison (LSC 230) - Conservation Biology

    My research program involves studying the ecology, population dynamics, and habitat relationships of animal populations in highly human-influenced landscapes.Research questions focus on population and genetic structure of small and isolated populations, and the role that spatial variation in habitat and resources plays in determining patterns of reproduction, survival, and dispersal of birds.

    I have two on-going projects on raptors.My research on the crested caracara in Florida examines how patterns of land use affect the speciesâ habitat use and demography.Currently, my collaborators and I are developing a Population Viability Analysis for this population.My research in Chile focuses on another caracara, a common predator on bird nests in the increasingly fragmented temperate rainforest on Chilo* Island.Future plans for this project involve studying nest defense behaviors of hosts and cues used by avian predators to find prey.I am also interested in the biodiversity value of small preserves in highly human-influenced landscapes.A future research plan is to assess the role of small preserves in the context of the central Connecticut landscape and their importance for biodiversity conservation in the northeast region.I am currently developing a biodiversity assessment program for birds and mammals at the Trinity College Field Station.

    Conservation education plays a major role in all my research.I strongly believe that scientists should 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.

    Prof. Michael O'Donnell (LSC 328) - Behavioral Ecology of Wildlife in Urbanizing Areas

    My research focuses on wild animals in urban, suburban, and developing environments; specifically, how these animals have adapted to these changing habitats. Some examples include: Feeding ecology of the common crow, the use of urban/suburban habitat by gray squirrels and raccoons, and the feeding behavior of urban/suburban gray squirrels.

    Current student research projects include:

    Prof. Craig Schneider (LSC 223) - Systematics and Ecology of Vaucheria species

    A systematic/ecological investigation of an important mud stabilizing yellow-green alga, Vaucheria, involves collections and observations in various Connecticut freshwater wetlands, as well as the manipulation of cultures in the laboratory. Various species are collected from ponds, rivers, streams, marshes, and drainage ditches throughout the state, and cultured in the lab with the purpose of isolating clonal populations. Most of the species in this genus worldwide are broadly euryhaline, which means that, unlike most other living organisms, they can acclimate from freshwater to full-strength sea water or even greater salinity. Some of the research problems of interest to my lab, aside from basic taxonomy and distribution of local populations, include comparisons of reproductive behavior of Vaucheria under a variety of temperature and photoperiod conditions, chemical constituencies of the various species that reside sympatrically, and the effects of salinity, desiccation, extremes of temperature, hypoxia and anoxia, and environmental pollutants on the survival of the several species isolated from Connecticut habitats.

    The Marine Flora of Bermuda

    My other research interests include morphological studies and the biodiversity of attached tropical marine algae. Currently, I am investigating the flora from the intertidal to deep subtidal waters of the Bermuda islands, and the phytogeographic relationships of Bermuda with the Caribbean and eastern Atlantic islands.

    Prof. Scott Smedley (LSC 309) - The Chemical Ecology of Insects

    As a chemical ecologist, I investigate how organisms use chemicals in their interactions with members of their own and different species. Insects, the most species-rich and ecologically diverse group of animals, are the primary subjects of study for me and my students. Our research focuses on how host plant chemistry influences the behavior and ecology of herbivorous insects and on how insects utilize chemicals as anti-predator defenses. This involves work in both the field (particularly during the summer months when local insects are active) and the laboratory (including projects with animals maintained in culture year-round). Since chemical ecology resides at the interface of biology and chemistry, much of our research effort is in collaboration with colleagues in chemistry.

    Various projects are ongoing. These include a study of the underlying physiology and morphology, as well as the adaptive significance of puddling, a behavior in which a male moth (Gluphisia septentrionis) drinks enormous volumes of puddle water (more than 600 times its body mass in a single bout!). This enables the moth to supplement nutrients present at low levels within its food plant and to invest these in its offspring. A second project examines the chemical nature and defensive role of a secretion produced by the immobile, and therefore vulnerable, pupal stage of a beetle (Subcoccinella vigintiquatuorpunctata). Another beetle (Chrysomela knabi) is the subject of an investigation into the adaptive significance of a dramatic developmental change in adult coloration and the relationship of this transformation to the beetle's chemical defenses. In addition to these and other projects that are underway, I am sure that new experimental systems will arise as we make discoveries of Connecticut's insect fauna.