Third Annual Sigma Xi Poster Session

Thursday, April 10, 2003

MacDonnell Atrium

3:00 p.m. to 5:00 p.m.


Marc Bartman

Faculty Mentor: April Hill


Evidence for the existence of a central class Hox gene in sponges

In contrast to some well-known animal models, very little is known of the developmental control of growth in sponges. This lack of information has limited our understanding of important events in the course of animal evolution. Genes present in animals that were among the first to branch off of the metazoan lineage will likely perform more restricted functions than those found in organisms that diverged later in animal evolution. Therefore, our research is centered around understanding the genetic constituency of developmentally important genes in sponges, and the functionality of morphogenetic regulatory programs in these organisms. In particular, we are focusing on the evolutionary and developmental significance of Hox genes in sponges. To this end, we performed a PCR-based survey and report here the isolation of the first Hox gene from a Poriferan genome. Clustal W placed the putative Hox gene isolated from Haliclona loosanoffi (Hox3Hl) with central class (PG-3) Hox genes and phylogenetic analysis consistently and unambiguously placed the Hox3Hl sequence in the PG-3 group. The Hox3Hl sequence has family-specific PG-3 amino acid residues that include F, R, C, P, and M at positions 2, 4, 7, 9 and 14 respectively. This finding is surprising given that only anterior and posterior class Hox genes have been found in cnidarians. Additionally, we used RT-PCR analysis to examine the expression profile of this Hox gene in developing sponge tissues. We show that the gene is expressed in free-swimming larvae as well as attaching and settling larvae. This data may provide significant insights into early animal evolution.

Sara Brady and Allison Schaffer

Faculty Mentor:  Diane Brousseau


Preliminary investigations of shelter competition among the Asian shore crab and native mud crabs

This study examined the potential impact of the recently introduced Asian shore crab, Hemigrapsus sanguineus on shelter utilization by two native species of mud crabs, Eurypanopeus depressus and Panopeus herbstii, using laboratory experiments and field sampling at two sites in western Long Island Sound (Black Rock Harbor, BRH; Milford Harbor, MH). Abundance and distribution patterns of these species differed at the two sites. Similar numbers of mud and Asian crabs were found under rocks at BRH, but Asian crabs outnumbered mud crabs 15:1 at MH. Asian crabs were most abundant at mid-tide level, whereas 90% of the mud crabs occurred low in the intertidal. This is likely due to the low tolerance for dessication exhibited by xanthid crabs (Grant and McDonald, 1979). At low tidal elevation, where most of the overlap occurred, between-site differences in under-rock microhabitat utilization were present. Only mud crabs were found beneath 75% of the rocks sampled at BRH, but at MH, mud crab species alone were found under only 5% of the rocks. Relative crab densities likely affect competitive outcomes and ultimately space utilization patterns. Results of shelter competition experiments conducted in the laboratory did not support the hypothesis that H. sanguineus affects shelter utilization by native mud crabs. The percentage of mud crabs occupying shell shelters remained unchanged when Asian crabs were present, but the percentage of Asian crabs occupying shell shelters decreased relative to controls in trials where mud crabs were present. These findings suggest that E. depressus and P. herbstii may affect patterns of habitat use by H. sanguineus, especially in the lower intertidal, where these species occur together. However, direct experimental manipulations in the field coupled with long-term monitoring are needed to fully understand the role of competitive interactions in determining the local distribution of these species.

Poster Presentation:  23rd Annual Milford Aquaculture Seminar, February 24-26, 2003     

Matthew Cahalane

Faculty Mentor:  Glenn Sauer


Induction of metallothionein in articular chondrocytes grown with steroid or TGFB supplementation

Human articular chondrocytes were grown in Dulbeccos Modified Eagle Medium (DMEM), DMEM supplemented with the steroid dexamethosome or DMEM containing differentiation factor TGFB.  The three sets of chondrocyte were harvested and studied for the short-term effects of the toxic metal ion Cadmium on cellular protein, DNA and the metal binding protein metallothionein (MT).  DNA levels were increased in cells grown with TGFB and decreased when grown with dexamethosome.  TGFB dramatically increased cellular protein levels relative to control and dexamethasome treated cells.  Short term (48 hr) treatment of cell culture with cadmium resulted in a dose-dependent induction of MT.  MT induction was highest in cells grown with dexamethasome and lowest in cells grown with TGFB.  The results suggest that MT expression is effected by differentiation of the chondrocytes caused by the media supplements tested. 

Kimberly A. Cullen

Co-researchers:  R.M. Damian Holsinger, Janetta G. Culvenor, Karolina Röyttä, Colin L. Masters and Geneviève Evin, Department of Pathology, The University of Melbourne and the Mental Health Research Institute, Parkville, Victoria 3010, Australia.


Redefinition of BACE transmembrane domain to include residues 455-460

Alzheimer's disease β-secretase, BACE, is a novel aspartyl protease with a single transmembrane domain located in its C-terminal region. To produce soluble BACE, we have expressed a construct corresponding to BACE putative ectodomain (residues 1 -460) in CHO-S mammalian cells. Unexpectedly, the protein was not secreted but was recovered in cell lysates, as determined by both Western blotting and assay for β-secretase activity. Biochemical, and microscopic studies of the cells indicate that BACEPD is associated with membranes. Our data suggest that BACE transmembrane domain extends to residues 455-460, a finding supported by Kyte-Doolittle hydrophobicity analysis of BACE transmembrane region.

Abbreviations:  AD: Alzheimer's disease; APP: amyloid precursor protein; BACE: β-site APP-cleaving enzyme; BACEPD: BACE protease domain; CHO-S: Chinese hamster ovary suspension cells; RT-PCR: reverse transcription-polymerase chain reaction; TMD: transmembrane domain.


Christine Curley and Christine McDonagh

Faculty Mentor:  Malcolm Hill


Molecular strategies for identifying species boundaries in marine invertebrates: a sequence-based approach

Marine invertebrates that are broadcast spawners (i.e., release gametes into the water) would seem to have genetically well-mixed populations with broadly dispersed larvae. This would lead to genetic homogeneity among populations, thus, reducing the opportunity for speciation to occur via traditional mechanisms (e.g., physical isolation). Despite these apparent barriers to speciation events, we have good evidence of speciation rates similar to, or higher than, those on land, which raises important questions about how speciation occurs in marine systems. We are interested in determining whether a polytypic sponge from the Caribbean (Anthosigmella varians) shows any evidence of reproductive barriers (i.e., fixed genetic differences), and have used a series of molecular approaches to address this question. Here we present data from sequence surveys using a cloning approach that demonstrate the utility of this technique for addressing evolutionary questions in marine systems. We have sequenced a substantial portion of the rDNA array from A. varians ranging from the 18S region to the 28S region. In addition, we have attempted to sequence intronic regions from the actin gene and the elongation factor gene. Promising sequences from the actin gene are currently being explored. Provided that appropriate molecular markers are identified, the sequencing approach we employed will be extremely valuable for attempts to understand microevolutionary dynamics in marine systems.

Sean Harrell and Eric Portante

Research Advisor:  Michael Brienza


Using physiology to teach physics

Our research consists of finding ways to use human physiology to teach physics. Since June 2002, we have been working on several specific experiments: how phase shifts are used in human auditory localization, and how the eye images objects. These experiments are just moving into one of the final testing phases: implementing them in one section of the General Physics Laboratory. Our research will continue this summer and most likely into next semester: we will be attending a conference at New York University this June, as well as continue to improve our designs for the auditory and optics labs, as well as develop other physiology based experiments.

Shawn Jennings

Faculty Mentor:  Tod Osier


Effects of light availability on chemical defenses of three deciduous tree species

Plants have evolved a sophisticated array of chemical defenses as protection from attack by insect herbivores.  Availability of resources can affect how plants allocate limited resources to defenses, versus to growth or maintenance needs.  To address this idea, we used a combination of field and lab experiments to determine variability in defensive chemistry among plants and subsequent effects on the herbivores that eat those plants.  We investigated the effects of light availability on resource allocation to chemical defenses for saplings of three deciduous temperate forest trees (Red Maple, Black Cherry and Sassafras) in mid-summer.  We bioassayed the foliage by feeding the larvae of the promethea moth on leaves from those trees.  Contrary to our predictions, the caterpillars grew better and faster on foliage from trees growing under high light.  Few studies have investigated plant defenses in mid-summer, as we did.  Much of the theoretical and empirical work conducted previously focuses on plant allocation to defenses in the spring, when plant growth and insect abundance is highest.  It is our feeling that food quality (availability of protein, water, etc…) may have played an important role in determining herbivore performance and overwhelmed the signal of defenses in the plants.  Pending chemical analyses of the foliage will offer insight into the relative levels of defenses in these plants and will help us determine how our results fit with the predictions of current plant defense theories.

Christopher Karch

Faculty Mentor:  Jen Klug


Factors contributing to the presence of algal blooms in the lower Housatonic River estuary

Estuaries are the highly biologically, chemically, and physically active systems where freshwater and seawater mix.  In these systems, phytoplankton, microscopic organisms capable of primary production, serve as the base of the food chain.   However, in some cases, phytoplankton can grow to levels that are detrimental to the system in which they are located.  These algal blooms impair recreation and can cause more serious problems as they decompose.  Bacteria that decompose the algae use oxygen and oxygen levels following algal blooms drop to levels that can kill fish and shellfish.  Our objective was to identify factors contributing to the presence of algal blooms in the lower Housatonic River estuary. Samples were collected from 3 sites within the estuary during the summer of 2002.  Salinity, temperature, rainfall, and water flow of the river were looked at in order to determine what was most influential in causing algal blooms.  Blooms only occurred during periods of high air and water temperature, low salinity, and low flow conditions. 

Nora Lopez and Kimberly Young

Faculty Mentor:  Malcolm Hill


Chemical and structural defenses in four species of temperate sponge against the hermit crab Pagurus longicarpus

The majority of studies examining anti-predator defenses in sponges have focused on tropical species, and these studies have found chemical defenses to be extremely effective at deterring predators.  Physical defenses have been found to be relatively ineffective, but few studies have looked for interactions between physical and chemical defenses in sponges.  We examined anti-predator defenses in four species of temperate sponge from Long Island Sound using a common hermit crab (Pagurus longicarpus) as a predator.  We identified potential synergistic interactions between structural and chemical defenses in Microciona prolifera.  Structural defenses were found to be effective in Cliona celata whereas artificial food containing chemical extracts from Haliclona loosanoffi, but showed no preference for spicule-laden artificial food.  Chemical extracts from Halichondria bowerbanki deterred predation, however in contrast to many tropical sponges, spicules were also deterrent.  No evidence of a synergism was observed in the H. bowerbanki feeding trials.  These preliminary results indicate that temperate sponges may use both chemical and structural defenses against a potential crab predator.  In addition, physical and chemical defenses in M. prolifera may interact synergistically.  We are currently examining additional aspects of both chemical and structural defenses for adult and larvae phases of the sponge life cycle including an identification of specific predators and an examination of levels of predation under field conditions.

Kathleen McAvoy

Faculty Mentor:  Jen Klug


River influences on estuarine Enteromorpha intestinalis

Freshwater inputs from rivers and streams alter salinity of coastal estuaries, and are also important conduits for the delivery of nutrients such as nitrogen and phosphorus.  Changes in these environmental factors may impact the growth of organisms in estuaries.  We studied the impact of freshwater inputs on primary producers in the lower Housatonic River estuary in Long Island Sound, CT.  We conducted a laboratory experiment with Enteromorpha intestinalis (a common green algae that is often found in nuisance blooms) collected from three sites around the estuary.  Site B was an exposed beach ~600m from the river mouth, site C was ~50m upriver from the mouth, and site F was ~2km upriver from the mouth.  Salinity and nutrient concentration varied across sites.  In a factorial design with five replicates, algae from the three sites were grown in four water treatments of varying ratios of Housatonic River water to Long Island Sound water (0H:100LIS, 15H:85LIS, 30H:70LIS, 45H:55LIS).  As the percentage of Housatonic River water increased, nitrogen and phosphorus concentration increased and salinity decreased.  Enteromorpha growth was higher in treatments containing Housatonic River water than in those containing only Long Island Sound water but there were significant site x treatment interactions.  Previous studies showed that Enteromorpha growth is stimulated by high nutrient concentration and depressed by low salinity; however, the reduction in growth at low salinity may be mitigated by increased nutrients.  Our results support these studies and suggest that at some sites, the negative impacts of freshwater due to reduced salinity may be outweighed by the positive impacts of the high nutrient concentration in Housatonic River water. 

Colleen McEvoy

Faculty Mentor:


Serial APACHE II scores in patients with prolonged intensive care unit stay

The purpose of this study was to assess the performance of serial acute physiology and chronic health evaluation (APACHE II) scores in predicting outcome of Intensive Care Unit (ICU)patients (PTS) with an ICU length of stay (LOS)>30 days. A prospective observational study over a period of fifteen months was conducted in a 40 bed medical-surgical ICU at a tertiary care teaching hospital.  Demographic data were collected using Project IMPACT (PI). APACHE II scores were recorded on admission and weekly for four weeks in PTS with a LOS>30 days.  Survivors were those PTS who were alive >two months after discharge from the hospital.  The data were analyzed using Student's t test.  Data from 2,878 PTS were evaluated.  Thirty-seven PTS had an ICU LOS >30 days (1.2%) and utilized 15% of the total ICU bed-days.  Fourteen PTS died in the hospital or within two months of their discharge.  Of the remaining 23 PTS, 19 were discharged to skilled nursing facility (SNF) and 4 PTS returned home.  There was a significant difference in the age of the survivors versus (vs) the non-survivors (53.5 vs 72.8, p=.001).  The mean admission APACHE II scores between the two groups were equal (22.5 vs 22.6).  After one week, the mean APACHE II scores of the survivors vs the non-survivors differed (15.2 vs 18.5) and reached statistical significance on weeks 2(15.8 vs 19.3, p=0.03), 3 (14.5 vs 20.1, p=0.004) and 4(12.9 vs 21.1, p=0.0006).  One year follow up revealed 3 PTS at SNF, 17 PTS at home, 1 PT expired, 2 PTS lost to follow-up.  Serial APACHE II scores may be useful in predicting outcome of patients with prolonged ICU stays. Further evaluation of serial APACHE II scoring appears warranted.

Caitlin O'Connor

Faculty Mentor:  April Hill


Expression of the Pax 3/7-like gene in Marine Sponges

Pax genes belong to a family of transcription factors that encode multiple and diverse DNA-binding domains. Pax family members are involved in the development and control of the central nervous system and other organs including the kidney, pancreas, and eye in triploblastic organisms. A few Pax family members have been identified in diploblasts (cnidaria and sponges) but their ancestral functions are not yet resolved. We report here the expression analysis of a Pax 3/7 family member in marine sponge tissue. We also present phylogenetic data that may aid in the understanding of the evolutionary diversification of the Pax gene family. The presence of Pax gene sequences in sponges (which lack nerve cells or any type of nervous system) presents an opportunity to determine their function before tissues evolved in animals.

Kathy Papayani

Faculty Mentor:  Glenn Sauer


The effect of T3, TGF-Beta, and Dexamethasone on the growth and development of the normal human articular chondrocyte extracted from the knee

The purpose of this experiment was to determine the effect that different growth factors and hormones had on human chondrocyte development and growth. The human condrocytes used were derived from normal human articular cartilage found in the knee (NHAC-kn) supplied from the Clonetics Chondrocyte Cell System, a system that quickly generates the NHAC-kn for experimental application in research. The growth factor TGF-Beta (TGFB) and the hormones dexamethasone (Dex) and triiodothyronine (T3) were used in this experiment. Their effect on the chondrocytes' ability to produce protein, on the cells' levels of DNA, and on the alkaline phosphate activity of the cells, were recorded. Assays were used to determine levels of protein, DNA, and alkaline phosphatase in the chondrocytes. The Lowry assay was used to determine the ug of protein the chondrocytes produced per dish. The DNA assay was used to determine the concentration of DNA in ng the chondrocytes produced per dish. The alkaline phosphate with the Lowry assay was used to determine the amount of enzyme produced per mg of protein was produced in each dish by chondrocytes living in different growth factors and hormones. For each treatment and for different days, the results were graphed from these three assays so that comparisons could be made and the effect of the growth factors and hormones could be determined.


After this experiment was performed and the results recorded and observed, a second experiment was performed involving different concentrations of TGFB. The cells were grown in different concentrations of TGFB to determine at which concentration the most protein, alkaline phosphates, and DNA was produced. Chondroytes are the only cell component of cartilage. Hyaline or articular cartilage provides protection in synovial joints, the most abundant type of joint in the body, by covering opposing bone surfaces and absorbing compression and stress placed on the joint through use. The cartilage prevents the bone ends involved in the joint from degrading or eroding due to friction when the bone ends rub together. It is tough, flexible, and avascular (containing no blood vessels). Condrocytes are essential for the preservation of cartilage because they produce and maintain the extracellular matrix of cartilage, which has the capacity to bear the weight planted on the joint. Articular cartilage is greatly researched because of its direct involvement in arthritis and joint injuries, which can cause disabilities.

Katharine E. Silva

Research Advisor:  Dr. Cathleen Wigand, Environmental Protection Agency, Atlantic Ecology Division, Narragansett, Rhode Island


Effects of nutrient enrichment of Spartina patens on Chlorophyll Levels

This experiment examined the chlorophyll levels in leaves of the salt marsh grass, S. patens. Chlorophyll levels can be correlated with amounts of photosynthesis taking place within a plant. Samples were taken from each plot. Pigments extracted were run through an HPLC instrument for calculation of chlorophyll a and b levels. The hypothesis was that S. patens under +N-P and +N+P treatments (specifically +N-P due to the high level of nitrogen without the abundance of phosphorous) would have the highest increase in rates of photosynthesis. Predictions were that the chlorophyll a and b levels would be higher in the samples enriched with +N-P and +N+P treatments. Treatments +N+P and +N-P showed to have the highest levels of both chlorophyll a and b.  Treatment +N+P had the highest of all the treatments. Treatment -N+P had the lowest levels of both chlorophyll a and b. The control (-N-P) levels were in between the highest and lowest levels. The experiment's results provide data to support the hypothesis. The nitrogen enriched patens showed higher levels of chlorophyll. Chlorophyll levels correlate with the photosynthesis rate of plants; the higher the chlorophyll level, the increase in photosynthesis, thus an increase in glucose produced.

Nicole E. Sparling and Marina C. Simeone ’02

Faculty Mentor:  Shelley Phelan


Characterization of the antioxidant protein 2 (Aop2) gene family:  Differential regulation in the oxidative stress response

Aop2 is a unique member of the thiol-specific antioxidant family of proteins known to reduce reactive oxygen species in the presence of thiol-containing electron donors.  It is also a candidate atherosclerosis gene in mice.  An analysis of Aop2 expression has revealed the existence of multiple transcripts not previously reported, each with a unique tissue distribution.  We have also determined one of these to be the highly related intronless gene Aop2-rs1, which appears to be exclusively expressed in testes.  Additionally, an Intron 1 specific probe identified two alternative transcripts not identified with the Aop2 specific probe.  Treatment of a murine hepatocyte cell line with glucose oxidase led to the specific and transient induction of the primary 1.47 kb transcript, while serum deprivation and restimulation regulated the expression of another transcript in a time dependent manner.  The effects of high fat diet on expression of these transcripts in heart and liver in atherosclerosis susceptible mice have also been analyzed.  Lastly, expression and purification of each encoded protein is allowing for functional characterization of their antioxidant activities.  Based on distinct transcriptional regulation, our data suggest that these alternative transcripts may play varying roles in response to oxidative stress and signaling pathways.

Christopher Szabo

Faculty Mentor:  Matthew Kubasik


Rate of enantiomeric conversion of helical peptides measured by dynamic NMR spectroscopy

Homo-oligomers of the amino acid alpha- aminoisobutyric acid (AIB) are known to form 310-helicies in solution.  These helical peptides, stabilized by intramolecular hydrogen bonds, exist in a dynamic equilibrium between two equally populated conformations:left-handed and right-handed helicies.  We have employed dynamic NMR spectroscopy to measure the rate of interconversion between the enantiomeric helicies in peptides six and eight residues in length.  Our hypothesis states that the octamer will have a slower rate of interconversion than the hexamer due to two more hydrogen bonds that stabilize its helix.

Jeffrey Tetrault

Faculty Mentor:  April Hill


Expression analysis of a BarH1 class gene in developing Halichondria larvae

We previously reported the isolation of a novel, Antennapedia-class, BarH1-like gene from screens of a marine sponge Halichondria cDNA library.  Here, we investigate the expression of that gene from both developmental time specific and spatial perspectives.  Specifically, we employed RT-PCR techniques to look at expression across six different larval developmental stages and adult disaggregated and re-aggregating tissue.  We found that the gene is highly expressed in newly released larvae (presumably a maternal message), after which expression is down-regulated.  The gene is again expressed in late stage free-swimming larvae up until they have settled and attached, where expression is again down-regulated.  Low levels of expression are observed in adult tissue with little difference in expression between disaggregated and re-aggregated tissues.  We also performed in situ hybridization to examine where the gene is expressed in adult tissue (housing developing embryos) and developing larvae.  Embryos and free swimming larvae exhibit high levels of BarH1 expression while adult maternal sponge tissues show little expression.  In situs to free swimming larvae show BarH1 expression to be concentrated toward the posterior end, with a gradient toward the anterior.  This polarity of expression during early development has been observed with antennapedia-class homeobox genes in other animals.  Our discovery of both the existence of this type of gene in sponges and its interesting developmental expression pattern may give us insight into the evolutionary conservation of animal body plans.

Jennifer Torp, Jeffrey Tetrault, Derek Bickhart

Faculty Mentors:  Olivia Harriott, Malcolm Hill, and April Hill


Molecular analysis of the bacterial community in the marine sponges Chondrilla nucula and Microciona prolifera

Studies have shown that marine sponges harbor a tremendous diversity of microorganisms.  The benefits provided by bacterial symbionts are thought to include nutrient assimilation, structural support and protection of the sponge from disease causing microbes.  It is difficult and sometimes impossible to grow and study bacterial symbionts in a lab due to their dependency on the host.  Our work focuses on the molecular characterization of bacteria associated with the marine sponges Chondrilla nucula and Microciona prolifera. In this study, total sponge community DNA from C. nucula and homogenized M. prolifera tissue was used as the source of symbiont DNAs.  Bacterial 16S rRNA sequences were amplified by using primers selective for eubacteria.  In both the C. nucula and M. prolifera amplifications, a single PCR product of approximately 1500 base pairs was obtained and cloned.  Eleven of the twenty-nine M. prolifera clones contained the appropriately sized insert, as well as forty-two of the forty-three C. nucula clones.  Amplified ribosomal DNA restriction analysis (ARDRA) of desirable clones was done with HhaI and Hpa II, and the banding patterns suggested that at least 15 pattern were present. The four unique M. prolifera and eleven C. nucula clones were partially sequenced and at least 500 base pairs of each clone were analyzed using BLAST, a web-based DNA sequence analysis program of the National Center for Biotechnology Information.  The clones were shown to have similarity to 16S rRNA sequences of unculturable marine symbionts.  Moreover, phylogenetic analysis inferred the existence of sponge-specific bacterial symbionts associated with sponges from geographically diverse environments.

Caitlin A. Vida and Kara A. Showalter, Cooper Union University, New York

Advisor:  CVS Robert S. Seamans Class 183 and Chief Scientist-Gary Jaroslow


Trends in sediment patterns related to El Niño and climate change in the southern California bight and the Gulf of California

The purpose of this study was to examine climatic variations reflected in varve patterns from sediment core samples taken within the anoxic region of Guaymas Basin, Gulf of California. Three two meter gravity cores, two on the east side of the basin and one on the west, were extracted and measurements of sedimentation layer thickness and varve color were taken and compared to detect anomalies related to climatic change, The oldest age of the cores were estimated to date back 48.5 years, 49.5 years and 29 years. A general darkening of the sediment cores over time was found in each core sample. In addition, a peak in dark layer thickness was observed every three to five years in two of the core samples. Finally, a peak in light layer thickness occurred every seven to eight years. The large scale change in varve color over time may be related to either a steady increase in terrigenous input or a decrease in biogenous sedimentation. In contrast to previous studies that found a decrease in both light and dark layer thickness during an El Niño event, this study demonstrates that the El Niño climatic cycle is represented in sedimentation patterns roughly every seven years as an increase in both light and dark layer thickness.