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.
Kathleen Archer (LSC 344) - The biology of sea slug - chloroplast
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.
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
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.
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
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.
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.
Kent Dunlap (LSC 245) - Electrocommunication & Physiology of
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
Robert Fleming (LSC 238) - Cell signaling and Developmental
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.
Lisa-Anne Foster (LSC 236) - Molecular Mechanisms of Host-Parasite
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.
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:
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:
the entire set of genes involved in heme biosynthesis
a hemA mutant of B. bronchiseptica
specialized strains of B. bronchiseptica to measure hemA
production under various environmental conditions
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
assay to detect heme-binding to H. capsulatum surface proteins
of mRNA to determine the specific genes expressed during iron-starvation
quantitation of heme available inside of macrophages during H. capsulatum
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
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.
Joan Morrison (LSC 230) - Conservation Biology
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.
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.
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.
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
Current student research projects
The effects of translocation
on female raccoon habitat use and infant survival. As the prevalence of
urban and suburban wildlife/human conflicts increase, there is little known
about the fate of nuisance animals (and their offspring) once they are
removed from their original den site. These field studies include radio-tracking
raccoons to determine habitat use and offspring survival. Read
an Environmental News Network story on this research.
habitat use and diversity of mammals at the Trinity
College Field Station in Ashford, Connecticut. These field studies
currently include measuring habitat use and relative abundance indices
of various mammals using scent station transects and "camera traps."
I am particularly interested in comparing the use and results of these
methods at the Field Station, with studies in urban/suburban habitats.
Foraging behavior of gray
squirrels looks at predation risk and behavioral adaptations, examining
whether squirrels that live in a protected urban/suburban area optimally
forage for their food. According to optimal foraging theory, squirrels
would seek to maximize energy gain while expending the least energy and
exposing themselves to the least risk of predation. These field studies
include establishing feeding stations, determining food preferences of
gray squirrels, and examining alarm (predator avoidance) behavior.
My home page has several
student abstracts from this research.
Craig Schneider (LSC 223) - Systematics and Ecology of Vaucheria
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.
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.