Date: 2014-08-01

Creator: Jenna Watling

Access: Open access

Since early July, I’ve been working on three projects. I’ve been studying parrotfish speciation, dissecting green crabs, and collecting samples of muscle tissue from blue mussels. My primary occupation is the study of parrotfish speciation with Dr. Carlon. He has found evidence of speciation through hybridization, which is has not been commonly observed. During the 2013-2014 academic year, he and I extracted DNA from fin or scale samples from Pacific parrotfish. Throughout the year and during this summer, we have been amplifying specific genes—nuclear and mitochondrial—using a polymerase chain reaction, confirming the amplification via gel electrophoresis, and preparing the samples for Sanger sequencing, which is done by the Nevada Genomics Center. Once we receive the sequencing results electronically, I use the program Geneious to check the quality of the individual sequences and resolve ambiguous calls (e.g., whether a specific base pair is an arginine or a cytosine) and align the sequences so we can compare them base pair by base pair. By examining both nuclear and mitochondrial genes, which evolve at different rates, we can hypothesize about the way in which different species arise. Green crab (Carcinus maenas) dissection is an early step in Aidan Short’s analysis of their diet. I assist in collecting tissue samples. We collect muscle tissue from the crabs’ claws. These samples will allow Aiden to differentiate between the crabs’ food and the crabs themselves. Then their carapaces are cut open and their entire stomachs are collected. In the near future, Aidan will use next-generation sequencing to identify any species present in the crab stomachs and quantify the abundance of these species’ DNA. Sequencing the crabs’ stomach contents is more precise and more complete than the older method of hard part analysis. The green crabs’ diet is of interest because green crabs are an invasive species and have been implicated in loss of sea grass beds and decreasing soft shell clam populations. Collection of tissue from blue mussels (Mytilus edulis) and bay mussels (M. trossulus) is a preliminary step for Dr. Sarah Kingston’s investigation of the genetic basis of variation in shell calcification rate under environmental conditions possible due to ocean acidification. She collects mussels from various sites along the Maine coast, marks each with a color and number, and records their buoyant weight. The buoyant weight allows Dr. Kingston to determine the mass of the shells without having to kill the mussels. In the first round of experiments, Dr. Kingston determined which of three experimental schemes (involving the manipulation of food levels, temperature, and pH) resulted in the greatest variation of shell calcification after two weeks. The harshest scheme—no food, high temperature, and low pH—resulted in the greatest variation, and this scheme will be used in the experiment going forward. After the experimental period, the mussels are re-weighed and tissue samples are collected. I assist in tissue sample collection; we cut open the mussels and remove the foot and the adductor muscle. In the next round of experiments, I will further assist by participating in mussel collection, monitoring tank conditions during the experimental period, and labeling and weighing the specimens. The DNA libraries obtained from the tissue samples will be sent away for next generation sequencing, and Dr. Kingston will begin looking for genetic variation associated with calcification rates. Final Report, summer 2014 student-faculty research.

Date: 2014-08-01

Creator: Amanda Howard

Access: Open access

Neuropeptides are small signaling molecules found throughout the nervous system that are responsible for influencing animal behavior. They consist of short amino acid chains and interact with cell-membrane receptors in order to regulate behavioral responses (Fig. 1a). The American lobster, Homarus americanus, has proven to be a strong model organism in which to study such activity due to the simplicity of the system and the wealth of existing knowledge about the animal. One neuropeptide found in H. americanus is a C-type allatostatin (AST-C). Allatostatins are a family of neuropeptides originally identified in insects that inhibits juvenile hormone production. The H. americanus AST-C has a pyroglutamate blocked N-terminus and an unmodified C-terminus (Fig. 1b). In addition to AST-C, a different, yet structurally similar neuropeptide has been found in H. americanus. This peptide has an unmodified N-terminus and an amidated C-terminus (Fig. 1c). Both forms of AST-C (referred to as ASTC-real and ASTC-like) also have a disulfide bond between their two cysteine residues. In the lobster, both peptides influence cardiac muscle contraction patterns and have been found in various tissues throughout the nervous system [1, 2]. In order to establish the purpose of the observed post-translational modifications, this study aims to find whether these peptides exist in other forms in the lobster and to determine their relative and absolute concentrations.Liquid chromatography-mass spectrometry (LC-MS) and tandem mass spectrometry (MS/MS) are often used in analytical chemistry to characterize complex samples and identify neuropeptides. First, sample components are separated by chromatography based on properties such as size and hydrophobicity. Using mass spectrometry (MS), peptides are protonated (positively charged) and their mass is determined from their measured mass-to-charge ratios. These peptides are lastly fragmented into many ions using MS/MS, which ultimately allows them to be sequenced in order to determine their identity. This summer, standards of the two AST-C peptides have been characterized by LC-MS/MS. The reduced forms of both peptides have been synthesized by chemically reducing the disulfide bond and were also analyzed by MS/MS. As expected, the structural stability provided by the disulfide bond prevented fragmentation during MS/MS analysis; that is, there was evidence of more fragmentation in the reduced forms than in the fully processed forms (Fig. 2). When looking for other forms of ASTC, these findings will facilitate the identification of the reduced forms in crustacean tissue.To assess the accuracy of the detection method used, detection limits were assessed by analyzing sample matrices augmented with known amounts of peptide standards. The smallest amount of peptide detected from a single injection was 25 fmol (2.5·10-14 mol) peptide. There appeared to be a strongly linear relationship between the amount of ASTC-real injected and the instrument response (chromatographic peak area) (R2=0.996, n=6). However, the relationship between the amount of ASTC-like injected and the instrument response was less linear (R2=0.802, n=5), and the calibration slope was more shallow, indicating that this peptide is more difficult to detect. This is possibly because ASTC-real, unlike ASTC-like, contains an arginine (R) and a histidine (H) residue, two basic amino acids susceptible to protonation. Therefore, it seems that ASTC-real is more easily protonated during the ionization process in MS analysis, causing it to be more readily detected.Lastly, ASTC-real has been identified in the pericardial organ (PO), a tissue responsible for delivering neuropeptides manufactured in the thoracic ganglion to the heart in order to control muscle contraction. ASTC-like is also believed to be present in the PO based on previous work in the Dickinson lab (E. Dickinson, unpublished data), but it is likely that it has not yet been detected in this study due to the detection limitations described above. To address these issues, more tissues will be pooled to increase the amount of peptide in each sample analyzed.Currently, tissue extraction methods are being optimized to eliminate phospholipid contamination and to maximize detection sensitivity. Specifically, two separate extraction solvents as well as a chloroform delipidation procedure are being tested. Future goals include quantifying peptide levels by adding a known amount of internal standard to the samples and comparing instrument responses for ASTC and for internal standard. Additionally, known amounts of peptide standard will be brought through the extraction process to determine the amount of peptide loss throughout this procedure. During the upcoming academic year, this study will be continued as an Honor’s project. Further research in these areas will ultimately help explain how neuropeptides interact to regulate behavior within the lobster and in more complex systems. Final Report of research funded by the Henry L. and Grace Doherty Charitable Foundation Coastal Studies Research Fellowship.

Date: 2014-08-01

Creator: Xuan Qu

Access: Open access

Central pattern generators are networks of neurons that produce rhythmic and repetitiveoutputs. These outputs control behaviors such as walking, breathing and digestion. In the Americanlobster, central pattern generators control the behavior of muscles in its foregut, which allows thedigestion of a variety of food types. The stomatogastric ganglion (STG) is a bundle of about thirtyneurons in the foregut of American lobsters. It has been studied extensively since each one of theneurons in it is both identifiable and produces simple patterned outputs. The analysis of American lobster’s stomach behaviors and the neural mechanisms controlling them could provide general insights into how rhythmic motor patterns for locomotion are produced. A large number of the neurons in the STG are modulatory neurons that use neuromodulators for at least part of their synaptic receptions. These neuromodulators are released by neurons and cause long-lasting changes in the synaptic efficacies of the targets. At present, many types of neuropeptides have been identified within the crustacean stomatogastric nervous system. The pyrokinins are members of one peptide family, PBAN. PBAN peptides all share the common Cterminalpentapeptide FXPRL-amide, in which X can be S, T, G, N, or V. Previous studies, using immunohistochemistry, have found that there are pyrokinin peptides present in both the STG and the cardiac ganglion (CG) of American lobsters. My research tests five different kinds of pyrokinin peptides, including PevPK1 (DFAFSPRLamide) and PevPK2 (ADFAFNPRLamide) from the shrimp L.vannamei (Torfs et al., 2001; Ma et al., 2010), CabPK1 (TNFAFSPRLamide) and CabPK2(SGGFAFSPRLamide from the crab C.borealis (Saideman et al., 2007;Ma et al., 2009) and Conserved Sequence (FSPRLamide) from the lobster, H.americanus (Ma, et al, 2008). ConservedSequence, the only pyrokinin identified in the American lobster so far, is highly conserved among many other pyrokinin peptides. Therefore, it is believed to be just a fragment with the complete sequence yet to be identified. Thus, we predicted that it might produce a weaker effect on the STG. Previous studies on the pyrokinin peptides have shown that in crabs, CabPK1, CabPK2 and LeucoPK (identified in an insect), all had a virtually identical effect on the CG, suggesting that the differences among these pyrokinin peptides are not important and the receptors for these peptides are the same. However, research done by Bowdoin students in 2011-2012 showed that among PevPK1,PevPK2, CabPK1, CabPK2, and Conserved Sequence, all but Conserved Sequence (not yet tested) had strong effects on the STG. However, only PevPK2 had an effect on the CG. My goal for this summer research was to determine whether or not there are differences between the responses of the STG to the different peptides in order to further determine the cause for the differences between the responses of the CG and those of the STG. The results from the extracellular recordings from the identified neurons in my research have shown that none of the five kinds of pyrokinin peptides affect the pyloric rhythm, which controls the pumping and filtering of food through the pylorus in Americanlobsters. They all, however, excite the gastric mill rhythm, which controls the movements of the teeth that grind up the food before it is transferred into the pylorus. Moreover, there is no significant difference among the effects of these five kinds of pyrokinin peptides. Conserved Sequence, which was predicted to produce a relatively weaker effect, proved to produce virtually identical effect asfour other kinds of pyrokinin peptides. Future research will focus on studying the differences between the STG and CG to determine the cause of the varied responses between them. Final Report of research funded by the Doherty Coastal Studies Research Fellowship.

Date: 2014-08-01

Creator: Lloyd Anderson

Access: Open access

Increased atmospheric CO2 due to the combustion of fossil fuels and subsequent oceanic uptake has led to a phenomenon known as ocean acidification: CO2 gas dissolved in the ocean lowers surface ocean pH and acidifies ocean waters, a process which has raised global concern. The purpose of my research was to investigate why a particular clam flat in Phippsburg, ME is not as productive as it used to be. This clam flat, located on “The Branch” in Phippsburg adjacent to Head Beach, has decreased to approximately a sixth of its former productivity in just over a decade. A possible explanation for this drop in clam bed productivity is acidification. I worked in a partnership with Bailey Moritz ’16, with the goal to measure indicators of ocean acidification in the clam flat and see if there was a difference in those indicators between productive and unproductive areas of the flat. Bailey’s focus was alkalinity, a quantification of the buffering capacity of seawater, where my specific research focus was on the effective collection of pH measurements. We were ultimately able to combine our alkalinity and pH measurements to calculate saturation state, an indicator of the susceptibility of clam shells to dissolution. I measured pH, a direct indicator of water acidity, from the top centimeter of the mudflat, the region where clam spat (juvenile clams) are seeded. The first few weeks of my fellowship time I spent researching the most accurate and precise way to measure pH in the field, and ultimately decided to measure pH on site using glass electrode probes. Sites 1 and 2 were located in a productive region of the flat, sites 4 and 5 were located in an unproductive region, and site 3 was located on the boundary between the two zones. Average pH values within the clam flat ranged from 6.9-7.5, and there was no significant difference in pH between productive and unproductive sites across the flat (Figure 1). The wide variations in pH across this clam flat could potentially be attributed to daily shifts in temperature, freshwater input, and biological productivity in the sediments. Low average pH values seen across all sites contribute to a low saturation state across the flat: our average calculated saturation state was 0.47, lower than similar data measured by Green et al. on a clam flat in South Portland in 2013, where average saturation state was 0.9. Our data indicate that the soft-shell clams at the productive sites in this particular Phippsburg clam flat are managing to survive in undersaturated (saturation state < 1) conditions. Since saturation state was low across both productive and unproductive sites, ocean acidification seems not to be the cause for the clams’ decline. However, other factors such as dissolved oxygen or sediment type may have combined with low saturation states to create a difference in productivity across the flat. In further research I would be interested to see how average pH at these same sites varies over a year-long period, which would give a better representation of the environment that the soft-shell clams are exposed to through yearly cycles. Final Report of research funded by the Rusack Coastal Studies Fellowship.

Date: 2014-08-01

Creator: Nora Hefner

Access: Open access

Gulf of Maine cod fisheries, once essential to Maine’s economy and culture, are currently in a state of collapse. Following a long decline throughout the 1800s and two collapses in the 1900s – one in the middle of the century and one in the 1990s, cod populations along the coast exist now as small fractions of their former bounty. Though the connection was largely forgotten in the twentieth century, fishermen in the nineteenth century attributed the decline of the cod fishery to the loss of alewives, an anadromous river herring upon which cod prey. Alewives have been cut off from their spawning and nursery habitat along much of the Gulf of Maine due to the damming of rivers that empty into the Gulf. My research is a part of an ongoing study that aims to establish the historical relationship between cod and other gadoid groundfish fisheries, their ecosystems, and anadromous alewives using spatial data from geographic information systems (GIS). GIS maps were created with the positions of 466 historical Gulf of Maine cod fishing grounds, identified using a database developed by fisheries scientist Ted Ames (whose work is largely responsible for fisheries scientists’ renewed interest in the groundfish-alewife connection). The spatial database generated from these data will be analyzed using a logistical regression to identify characteristics of fishing grounds that define them as fishing grounds, as well as characteristics that determine the relative quality of individual fishing grounds. The Ames database contains data in two main categories: biophysical (ecosystem characteristics) and socioeconomic (infrastructure). The focus of my research was on generating two specific data sets from historical literature, government reports, and experts in the field, and on mapping that data using GIS software (see Figure 1). The first was a list of rivers that supported annual alewife runs before the mid-twentieth century cod groundfish fishery collapse. Using GIS software, I mapped the locations at which these rivers enter the ocean, creating spatial data that show the point at which cod in the Gulf and alewives in the rivers would meet. The second data set was a list of ports and harbors that supported the groundfish industry, also before the mid-twentieth century collapse. These locations were mapped as the areas from which fishing boats would set out in pursuit of groundfish, again creating a set of spatial data points. Both of these data sets were added to the existing spatial database. My data and Ames’ data will be used to calculate distances between individual groundfish fishing grounds and historic alewife runs and between fishing grounds and ports and harbors. Statistical analyses will determine both whether those two factors have any significant relationship with fishing ground quality and the nature of their effects, if any. Ultimately, the results of these analyses will contribute to an increasingly detailed picture of the Gulf of Maine as it existed – physically, ecologically, and economically – when it still supported astoundingly large populations of cod and other groundfish. With a better idea of what the system looked like when it worked properly, we can make a more informed and focused attempt to rebuild it. This research provided me with opportunities to develop practical skills like use of GIS software, contacting and collaborating with scientists, researchers, and government agencies in my field, and data management. I also gained a greater understanding of and appreciation for the complexity and challenge of trying to bring research from the science level to management policy and action. Final Report of research funded by the Cooke Environmental Research Fellowship

Date: 2014-08-01

Creator: Christine Walder

Access: Open access

Ascophyllum nodosum, the dominant intertidal macroalgal species from Maine to Canada, plays an important role in buffering intertidal stresses and supports a variety of organisms such as molluscs, crustaceans, fish and birds. A. nodosum is harvested commercially for use in fertilizers and food additives, and landings have been increasing in Maine in recent years. The ecological impact of removing the rockweed canopy was assessed in a comparative study between Kent Island in the Bay of Fundy, New Brunswick, Canada and Orr’s Island in Harpswell, ME, USA. Paired 2x2m control and experimental plots were set up, harvested, and surveyed monthly during the summers of 2013 (15 plots on Kent Island) and 2014 (an additional 9 plots on Kent Island and 20 on Orr’s Island) in a BACI design (Before, After, Control, Impact). One square meter surveys were conducted to determine algal species richness, algal percent secondary cover, and megafauna abundance and diversity. Surveys were designed to assess the overall diversity within plots and count/identify all present species. Initial t-tests of Kent Island data show a short-term reduction in amphipods and isopods, Carcinus maenas (green crabs), and Littorina obtusata (smooth periwinkles) and a short-term increase in Littorina littorea (common periwinkles) (p Final Report of research funded by the Rusack Coastal Studies Fellowship (2014).

Date: 2024-03-20

Creator: Katharine Kurtz

Access: Open access

Cities need more green spaces to adapt to climate change and facilitate community resilience. However, successfully managing green spaces is challenging. City governments consistently employ top-down management practices that limit the benefits, usage, and perception of such spaces as Nature. Further, current management practices overlook socio-cultural factors important to residents. Using the existing categories of urban green spaces (UGS) and informal green spaces (IGS), this article situates the cultural practice prendersi cura as a way to conceptualize successful, bottom-up green space management. The term prendersi cura, meaning “to take care of” in Italian, emerged through interviews in Perugia, Italy, and reflects the socio-ecological value of IGS and the disconnect between residents and city-managed UGS. This study employed mixed methods, combining 10 weeks of participant observation, 13 interviews, and GIS analysis to understand the relationship between Perugians and their green spaces. Results indicate that interviewees did not describe city-supported UGS (i.e. top-down green spaces like parks or historic gardens) as Nature, even if they were areas of dense vegetation and recognized by the City of Perugia in GIS analyses. In contrast, interviewees described IGS (i.e. community gardens, vacant lots, or potted plants) that were unrecognized in city GIS visualizations as Nature, indicating a stronger attachment to green spaces when interviewees had active roles in their management or witnessed community-based management practices. This paper demonstrates the importance of managing green spaces through a socio-ecological framework that considers user perceptions and cultural values. To allow greening initiatives to reach their full potential, it is critical to embrace local values and participation in management practices.

Date: 2015-03-01

Creator: Aidan W. Short, David B. Carlon

Access: Open access

A new wave of green crabs Carcinus maenus is sweeping through the Gulf of Maine (GOM). While first reports of green crabs in the GOM date from the early 1900s, populations in southern GOM have exploded in the last five years. In the Casco Bay region, this unusually high abundance is associated with poor commercial shellfish landings and the decline of eel grass habitat (Zostera marina). To determine the mechanistic roles green crabs play in direct and indirect ecological interactions, it is important to understand diet breadth, and how feeding preferences change in response to ecological context. Since green crabs are omnivorous, traditional approaches to diet analysis via hard parts suffer from substantial bias. We are using DNA barcoding and next generation sequencing (NGS) to analyze green crab diets from a longitudinal sampling design in Casco Bay. In addition to a temporal dimension, our design includes two habitats: clam flats and eel grass beds. We have now sampled ~ 1000 crabs and have processed 460 individual stomachs from a range of sizes and both sexes. Here we will present: our sampling design, our NGS pipeline, and preliminary analysis from a lobster-specific (Homarus americanus) probe. Presenting author status: Undergraduate Preferred presentation type: Poster Preferred topics: 3. Biological invasions; 18. Molecular ecology Benthic Ecology Meeting, 2015 Quebec City, Canada Aidan Short was an undergraduate student at Bowdoin College when this research was conducted.

Date: 2014-08-01

Creator: Jack Mitchell

Access: Open access

DNA Barcoding is the identification of organisms through the use of a standardized portion of the genome, a concept first suggested by Hebert, et al (2003) and since developed to include standard databases and many campaigns internationally to identify and barcode all species in the world. Because DNA barcoding uses molecular data, rather than morphology, to identify organisms, it allows for the identification of organisms that are morphologically similar or have been processed to the point of unrecognizability. Barcoding has the potential to streamline and enhance conservation efforts drastically. Its "quick and easy" identification process allows better fisheries management, market regulation to ensure vendors are selling what they say they're selling (no more horsemeat burgers or dolphin sushi), and greater enforcement of regulations against the killing and selling of endangered animal products (Minhos et al., 2013). In my work this summer, I've been using DNA barcoding to examine the dynamics of a community of larval fish off the coast of Oahu through a seven-year longitudinal barcoding study. Fish larvae are very hard to identify morphologically because they lack obvious identifying characteristics. For this reason, barcoding is essential for accurately understanding the community structure of such fish. In my work, I analyze a set of sequences from the 5-prime region of the mitochondrial gene cytochrome oxidase subunit 1, widely used as a barcode in the animal kingdom, gathered from fish larvae collected off the coast of Oahu by the University of Hawaii Manoa Biology 301L class. The sampling consisted of a series of oblique plankton tows taken at three depths (5m, 25m, and 50m) between January and April every year from 2007 to 2013. During this period, a total of 833 fish larvae were sampled and sequenced. Using the Barcode of Life Data Systems (BOLD Systems) Identification Engine, I was able to identify 78% of all specimens to family-level or better, representing about 25% of the 202 families of shore fishes known to occur in Hawaiian coastal waters. The data stratification consisted of 7 years, each with three depths and 56 family groups, a 21 by 56 data matrix. In order to see the patterns of the matrix, I used Principal Components Analysis, a form of ordination, which distills multidimensional data to a form that is more easily visualized. This ordination revealed that 2009 and 2011 had highly anomalous community structure in which there were large increases in abundance (greater than three (3) Standard Deviations from the mean) of 12 family groups in each year, indicating concerted change in the structure of ichythoplankton in those years, though the families may be represented by a low number of specimens in the sample. Because these families had little to no representation in other years, we are able to rule out the possibility of results being skewed by a couple of families that showed up in our nets by chance that don't reflect the actual community structure. In these years, the highly anomalous families did not overlap, indicating that the factors causing the anomalies were non-identical. In 2009 there were eight families that deviated from the mean by over four (4) Standard Deviations, and in 2011 there were ten. Though the biggest groups of deviant families in both years were reef fish and mesopelagic fish, tropical habitat ranged from shallow water benthic (sea-bed) fish such as Ophichthidae, to bathypelagic (deep sea) fish such as the anglerfish family Ceratiidae. In my last few weeks working on this project I am exploring what environmental factors may have had a hand in such anomalies. El Niño cycles may have had a hand, as there was a weak La Niña (slightly cooler waters) anomaly leading into 2009, and a very strong La Niña (drastically cooler waters) anomaly leading into 2011 ("Cold and Warm Episodes by Season," 2014). The differences in community structure I detected had different signs, that is the co-variance of fish families was different for each of these years. This suggests that water temperature itself may not be causing these ecological patterns. A more likely hypothesis links the effects of El Niño/La Niña on oceanographic circulation throughout the Pacific and even near-shore in the Hawaiian Islands. These changes can drive differences in the delivery of larvae to the islands, as well as advection away from the islands. Further research in the remainder of the summer will attempt to gather more information on what may have caused the community structure anomalies. Final Report of research funded by Mary Lou Zeeman’s NSF grant - Computational Sustainability (NSF-CCF-0832788).

Date: 2014-08-01

Creator: Tricia Hartley

Access: Open access

In many animals, there are groups of neurons, known as central pattern generators (CPGs), which are capable of controlling major everyday life functions. CPGs are responsible for functions that require patterned rhythmic activity, such as the heartbeat, digestion and locomotion. A CPG called the cardiac ganglion, consisting of only nine neurons, controls the rhythmic beating of the heart of the American lobster, Homarus americanus, by stimulating the muscle cells of the heart.My summer consisted of two separate projects in Patsy Dickinson’s neurophysiology lab, both studying the interaction of the cardiac ganglion with neuropeptides. These neuropeptides, GYSDRNYLRFamide (GYS) and SGRNFLRFamide (SGRN) are released hormonally into the cardiac neuromuscular system. The overarching goal of both projects was to determine the role of these neuropeptides in the lobster’s cardiac neuromuscular system.For my first project, I studied the interaction of the neuropeptide GYS with the stretch receptors of the lobster heart. Previous research has found these stretch receptors to be a form of excitatory feedback from the lobster heart to the cardiac ganglion, as heartbeat amplitude and frequency increase as heart is stretched. Further, the dendrites along the cardiac ganglion have been found to be stretch-sensitive, meaning when these dendrites were cut, this excitatory response is no longer observed. By stretching the heart with the dendrites intact and with GYS and next when the dendrites were cut and with GYS, the goal of this project was to determine if GYS would alter the feedback of the stretch receptors back to the cardiac ganglion to change heartbeat frequency and amplitude. Unfortunately, the intricacy involved in being able to cut the dendrites while allowing the heart to continue to beat proved very difficult and I moved on to my next project.The goal of my next project was to examine the interactions of the neuropeptides GYS and SGRN with the decreased and increased presence of nitric oxide, the second form of feedback from the heart muscle to the cardiac ganglion. Previous research shows nitric oxide as having an inhibitory effect, decreasing heartbeat amplitude and frequency. By applying both GYS and SGRN to both the isolated cardiac ganglion and the whole heart in the presence of both a nitric oxide inhibitor and donor, the hope is to be able to determine the interaction of these peptides with and without the presence of the feedback of nitric oxide. Because I started this project later in the summer, with the assistance of Sophie Janes’ data, I have been able to look at the effects of GYS on the whole heart, in addition to the combination of GYS with L-NA, a nitric oxide inhibitor. So far, the data has shown that the combination of GYS with L-NA causes less of a decrease in heartbeat frequency than GYS alone, which shows a significant decrease. We predict this is because GYS enhances the nitric oxide pathway, while L-NA is blocking the nitric oxide pathway, thus giving insight into the role of GYS within the lobster’s cardiac neuromuscular system. For my senior independent study I hope to continue this research and be able to continue to compile data for both SGRN and GYS on the isolated cardiac ganglion as well as on the whole heart, with a nitric oxide inhibitor and donor. Final Report of research funded by a Doherty Coastal Studies Research Fellowship.