Life Sciences Commons^™

Neural Compensation In Response To Salinity Perturbation In The Cardiac Ganglion Of The American Lobster, Homarus Americanus, Josephine P. Tidmore

Honors Projects

Central pattern generator (CPG) networks produce the rhythmic motor patterns that underlie critical behaviors such as breathing, walking, and heartbeat. The fidelity of these neural circuits in response to fluctuations in environmental conditions is essential for organismal survival. The specific ion channel profile of a neuron dictates its electrophysiological phenotype and is under homeostatic control, as channel proteins are constantly turning over in the membrane in response to internal and external stimuli. Neuronal function depends on ion channels and biophysical processes that are sensitive to external variables such as temperature, pH, and salinity. Nonetheless, the nervous system of the American …

Modulation Of The Crustacean Cardiac Neuromuscular System By The Sly Neuropeptide Family, Grant Griesman

Honors Projects

Central pattern generators (CPGs) are neuronal networks that produce rhythmic motor output in the absence of sensory stimuli. Invertebrate CPGs are valuable models of neural circuit dynamics and neuromodulation because they continue to generate fictive activity in vitro. For example, the cardiac ganglion (CG) of the Jonah crab (Cancer borealis) and American lobster (Homarus americanus) contains nine electrochemically coupled neurons that fire bursts of action potentials to trigger a heartbeat. The CG is modulated by neuropeptides, amines, small molecule transmitters, gases, and mechanosensory feedback pathways that enable flexibility and constrain output. One such modulator, the …

Using Reflex Actions To Predict Delayed Post-Harvest Mortality Of American Lobster (Homarus Americanus) In Maine’S Lobster Supply Chain, Cassandra Leeman

Electronic Theses and Dissertations

In live seafood industries, maintaining product quality and survivorship are critical aspects of the supply chain infrastructure. Post-harvest mortality in the American lobster (Homarus americanus) fishery can result in a significant loss in revenue for the largest single species fishery in North America. In Maine, the wholesale lobster distribution supply chain directly and indirectly supports state and local economies, providing almost $1 billion in revenue and dominates the fishery, producing 82% of the total lobster landings in the USA (Donihue, 2018; NOAA, 2021). However, at least 2% of the lobster landed in Maine die before they reach consumers, representing an …

Effects Of Myosuppressin, A Peptide Neuromodulator, On Membrane Currents In The Crustacean Cardiac Ganglion, Anthony Yanez

Honors Projects

Central pattern generators are neural circuits that can independently produce rhythmic patterns of electrical activity without central or periphery inputs. They control rhythmic behaviors like breathing in humans and cardiac activity in crustaceans. Rhythmic behaviors must be flexible to respond appropriately to a changing environment; this flexibility is achieved through the action of neuromodulators. The cardiac ganglion of Homarus americanus, the American lobster, is a central pattern generator made up of four premotor neurons and five motor neurons. Membrane currents in each cell type, which can be targeted for modulation by various molecules, generate rhythmic bursts of action potentials. …

Determining The Sites At Which Neuromodulators Exert Peripheral Effects In The Cardiac Neuromuscular System Of The American Lobster, Homarus Americanus, Audrey Elizabeth Jordan

Honors Projects

Networks of neurons known as central pattern generators (CPGs) generate rhythmic patterns of output to drive behaviors like locomotion. CPGs are relatively fixed networks that produce consistent patterns in the absence of other inputs. The heart contractions of the Homarus americanus are neurogenic and controlled by the CPG known as the cardiac ganglion. Neuromodulators can enable flexibility in CPG motor output, and also on muscle contractions by acting on the neuromuscular junction and the muscle itself.

A tissue-specific transcriptome gleaned from the cardiac ganglion and cardiac muscle of the American lobster was used to predict the sites and sources of …

Interaction Of Stretch Feedback And Beat Regularity In Response To Amgseflamide In The Heart Of Homarus Americanus, William Allen

Honors Projects

Central pattern generators (CPGs) are neural circuits whose component neurons possess intrinsic properties and synaptic connections that allow them to generate rhythmic motor outputs in the absence of descending inputs. The cardiac ganglion (CG) is a nine-cell CPG located in the American lobster, Homarus americanus. Stretch of the myocardium feeds back to the CG through mechano-sensitive dendrites and is thought to play a role in maintaining regularity in the beating pattern of the heart. The novel peptide AMGSEFLamide has been observed to induce irregular beating patterns when applied at high concentrations. This study investigated the interaction between stretch-related feedback …

Responses Of Central Pattern Generators In The American Lobster Stns To Multiple Members Of A Novel Neuropeptide Family, Benjamin Harley Wong

Honors Projects

Neuropeptides are important modulators of neural activity, allowing neural networks, such as the central pattern generators (CPGs) that control rhythmic movements, to alter their output and thus generate behavioral flexibility. Isoforms of a neuropeptide family vary in physical structure, allowing potentially distinct functional neuromodulatory effects on CPG systems. While some familial neuropeptide isoforms can differentially affect a system, others in the same family may elicit indistinguishable effects. Here, we examined the effects elicited by members of a novel family of six peptide hormone isoforms (GSEFLamides: I-, M-, AL-, AM-, AV-, and VM-GSEFLamide) on the pyloric filter and gastric mill CPGs …

Mechanisms Underlying Variable Responses To The Neuropeptide C-Type Allatostatin (Ast-C) Across Isoforms And Among Individuals In The American Lobster, Homarus Americanus, Audrey J. Muscato

Honors Projects

Central pattern generators (CPGs) produce patterned outputs independent of sensory input. The cardiac neuromuscular system of the American lobster (Homarus americanus) is driven by a CPG called the cardiac ganglion (CG), which is composed of nine neurons, making it a model system of study. Modulation of CPGs allows for functional flexibility. One neuropeptide family that modulates the CG is C-type allatostatin (AST-C I-III). Previous research has shown variation in the responses of the CG across the three isoforms and among individuals. First, we investigated why AST-C I and III elicit responses that are more similar to each other than they …

Response Of Early Life Stage Homarus Americanus To Ocean Warming And Acidification: An Interpopulation Comparison, Maura K. Niemisto

Electronic Theses and Dissertations

Anthropogenic carbon released into the atmosphere is driving rapid, concurrent increases in temperature and acidity across the world’s oceans, most prominently in northern latitudes. The geographic range of the iconic American lobster (Homarus americanus) spans a steep thermal gradient and one of the most rapidly warming oceanic environments. Understanding the interactive effects of ocean warming and acidification on this species’ most vulnerable early life stages is important to predict its response to climate change on a stage-specific and population level. This study compares the responses of lobster larvae from two sub-populations spanning New England’s north-south temperature gradient (southern …

Interannual Variability In American Lobster Settlement: Correlations With Sea Surface Temperature, Wind Stress And River Discharge, Mahima Jaini

Electronic Theses and Dissertations

Recruitment to benthic marine populations is fundamentally a biophysical problem. The American Lobster Settlement Index is an annual diver-based survey of the young-of-year American lobsters (Homarus americanus) found in inshore nurseries in New England, USA and Atlantic Canada at the end of the postlarval settlement season. The considerable interannual variability in the settlement index suggests that environmental factors play an important role in regulating planktonic larval supply and transport. In this study, I focused on the longest settlement time series from three oceanographically contrasting regions: Midcoast Maine, coastal Rhode Island and the lower Bay of Fundy. Sampling in these regions …

Biology And Ecology Of Larval Lobsters (Homarus Americanus): Implications For Population Connectivity And Larval Transport, Eric R. Annis

Electronic Theses and Dissertations

The connectivity of marine populations and the degree to which they are considered open or closed has important implications for the ecology, management, and resilience of commercially harvested species. Larval exchange is a primary determinant of the level of connectivity between populations, and this thesis examines the intrinsic and extrinsic factors influencing larval transport and the distribution of larvae of the American lobster (Homarus americanus). The potential for larval transport is directly proportional to the planktonic larval duration. Our field data suggest development times in situ were up to three times faster than previous laboratory development times, indicating that potential …

The Use Of Polyphosphates To Maintain Yield And Quality Of Whole Cooked, Cryogenically Frozen Lobster (Homarus Americanus) And The Use Of Sorbitol And Tocopherol To Maintain Quality Of Whole Cooked, Cryogenically Frozen Crab (Cancer Irroratus), Beth Louise Calder

Electronic Theses and Dissertations

The lobster fishery is valuable to Maine seafood processors, a commodity worth over $160 million dollars in 2001. Jonah and Rock crab are underutilized Maine seafood species, which are incidentally caught with lobster. Maine seafood processors could process this non-essential catch, and lobster into high quality frozen seafood products to increase national and international markets, which may have a significant economic impact. Cryogenic freezing can retain high quality texture and flavor attributes in seafood. Freezing can still cause cellular damage, however minimal. Sodium tripolyphophate (STP) and sorbitol are noted for their cryoprotectant effects, and tocopherol has been found to have …