Life Sciences Commons^™

Comparing Ionoregulation And Modes Of Nitrogen Excretion Across The Life Cycle Of Parasitic And Non-Parasitic Lamprey Species, Shannon Davidson

Theses and Dissertations (Comprehensive)

Abstract

Ionoregulation and nitrogenous waste (N-waste) metabolism in fishes has been extensively documented in teleosts and elasmobranchs, but less so in lampreys (Petromizontiformes). All lamprey species undergo metamorphosis which drastically changes their physiology and modes of feeding. However, differences in ionoregulatory mechanisms due to anadromous versus non anadromous life history strategies emerge following metamorphosis in different lamprey species. Furthermore, some species, such as anadromous juvenile sea lamprey (Petromyzon marinus), are parasitic and migrate to seawater (SW) to ingest blood protein from host fishes, while juveniles of freshwater (FW), non-parasitic species, such as the American brook lamprey …

Molecular Characterization Of The Mummichog (Fundulus Heteroclitus) Ovarian Steroidogenic Pathway And Implications For Exogenous Estrogen Effects During Follicular Development, Thiviya Kanagasabesan

Theses and Dissertations (Comprehensive)

This study investigated ovarian development in Fundulus heteroclitus (mummichog), through molecular characterization of key mediators in the ovarian steroidogenic pathway; these included ovarian StAR (steroidogenic acute regulatory protein), cytochrome P450 enzymes, estrogen receptors (ERα, ERβ1 and ERβ2), and gonadotropin receptors (FSHr and LHr); additionally, hepatic vitellogenin (VTG1) and ERs, and brain P450 aromatase (P450arom; CYP19b) were studied. Fish were staged into cortical alveolus, vitellogenic, early mature, late mature, and ovulating stages of maturation; blood (plasma), ovary (tissue and isolated ovarian follicles per stage), liver, and brains were collected. Testosterone (T), 17β-estradiol (E₂) and maturation inducing steroid (MIS), measured …

Changes In Brain Water Content In The Rainbow Trout (Oncorhynchus Mykiss) And In The Goldfish (Carassius Auratus) Due To High External Ammonia Exposure, Phillip Q.H. Pham-Ho

Theses and Dissertations (Comprehensive)

In fishes, hyperammonemia may occur following feeding or exposure to abnormally high concentrations of environmental ammonia due to sewage effluents, agricultural run-off and in crowded aquaculture pens. Increased internal ammonia can result in hyperactivity, convulsions, coma and death. In mammals, it is also associated with potentially fatal brain edema, in which the accumulation of intracellular water results in swelling, increased intracranical pressure and herniation leading to death. Recently it was shown that rainbow trout (Oncorhynchus mykiss) and goldfish (Carassius auratus) experience brain swelling following exposure to high external ammonia (HEA). However, the mechanism of ammonia-induced brain …

The Influence Of Abiotic Factors On The Uptake And Elimination Of 3-Trifluoromethyl-4-Nitrophenol By Larval Sea Lamprey (Petromyzon Marinus), Benjamin Livingston Hlina

Theses and Dissertations (Comprehensive)

The backbone of sea lamprey (Petromyzon marinus) control in the Great Lakes is the use of the piscicide, 3-trifluoromethyl-4-nitrophenol (TFM), which is applied to streams containing larval sea lampreys. However, TFM effectiveness can be influenced by abiotic factors such as pH and temperature, which fluctuate daily and seasonally. The objectives of this thesis were to evaluate the influence of pH, temperature, and season on the toxicity, uptake, and elimination of TFM by larval sea lamprey. Radio-labeled TFM (¹⁴C-TFM) was used to determine how TFM uptake rates varied at different water pHs or temperatures during exposure to …

The Role Of Oxidative Stress In The Mechanisms Of Ammonia-Induced Brain Swelling And Tolerance In The Goldfish (Carassius Auratus), David F. Jones Lisser Mr.

Theses and Dissertations (Comprehensive)

Toxic build-ups of ammonia can cause potentially fatal brain swelling in mammals, but such swelling is reversible in the anoxia- and ammonia-tolerant goldfish (Carassius auratus). The mechanisms of ammonia-induced brain swelling and tolerance remain elusive, but several studies have suggested a role for reactive oxygen species (ROS), which may damage proteins and lipids in the plasma membrane of astrocytes in the brain. As a result, osmotic gradients across cell membranes may be altered leading to water uptake by astrocytes and swelling. While a role for ROS has been proposed in mammals, no studies have addressed this question in …

A Missing Link In The Ionoregulatory Strategy Of Larval Sea Lamprey (Petromyzon Marinus) And African Lungfish (Protopterus Annectens): A Closer Look Into The Role Of The Non-Gastric H+/K+-Atpase, Justine E. Doherty

Theses and Dissertations (Comprehensive)

Fishes living in freshwater need to actively compensate for the diffusive loss of ions and osmotic gain of water. The gill is the primary organ of ion regulation and contains an array of ion transport proteins to help maintain homeostasis. Two of the more well studied ion pumps are the Na⁺/K⁺-ATPase (NKA) and vacuolar type proton ATPase (V-ATPase). This thesis focuses on another ion pump known as the non-gastric H⁺/K⁺-ATPase (ngHKA). The ngHKA (gene: atp12a) has not been found in any of the teleost fishes, indicating loss from that lineage. In …

Estimates Of Persistent Inward Current In Human Motor Neurons During Postural Sway, Ryan Foley, Jayne M. Kalmar Dr.

Theses and Dissertations (Comprehensive)

Persistent inward current (PIC) is a membrane property critical for increasing gain of motor neuron output. In humans, most estimates of PIC are made from plantarflexor or dorsiflexor motor units with the participant in a seated position with the knee flexed. This seated and static posture neglects the task-dependent nature of the monoaminergic drive that modulates PIC activation. Seated estimates may drastically underestimate the amount of PIC that occurs in human motor neurons during functional movement. The current study estimated PIC using the conventional paired motor unit technique which uses the difference between reference unit firing frequency at test unit …

The Effects Of Lampricide 3-Trifluoromethyl-4-Nitrophenol Toxicity On The Gills Of Larval Sea Lamprey And Non-Target Rainbow Trout And Lake Sturgeon, Lisa A. Sorensen

Theses and Dissertations (Comprehensive)

The pesticide, 3-trifluoromethyl-4-nitrophenol (TFM), is widely used in the Great Lakes to control invasive sea lampreys (Petromyzon marinus) populations, but much about its sub-lethal effects remains unknown. A better understanding of its toxicity is needed to improve TFM effectiveness and to protect non-target organisms from its potential adverse effects. The objectives of this thesis were to test the following two hypotheses: (1) impairment of mitochondrial ATP production by TFM interferes with ATP-dependent ion-uptake by fish, leading to altered electrolyte balance, and (2) perturbations of gill function by TFM are exacerbated in soft, ion poor water (SW; 40 mg …

Physiological & Cellular Mechanisms Of Ammonia Tolerance In The Goldfish (Carassius Auratus), Sanya Sidhu

Theses and Dissertations (Comprehensive)

Ammonia may increase in the blood and tissues of fishes following feeding or exposure to high concentrations of environmental ammonia arising from the degradation of organic matter in aquatic environments, sewage effluent, and run-off from landfills. Ammonia may be detoxified using the enzyme glutamine synthetase (GS), which catalyzes the conversion of ammonia to glutamine. It has been suggested, however that build-ups of glutamine within the astrocytes of the brain can cause brain swelling by increasing intracellular osmolarity and water uptake by the cells. Using in vivo and in vitro approaches, the goal of this thesis was to determine if: (i) …