Pesticides are commonly used around the world for a multitude of different purposes and on diverse habitats, including agricultural fields, wetlands, and personal lawns and gardens. Currently, acetylcholinesterase (AChE)-inhibiting pesticides are among the most prevalently used chemical pesticides in the United States. A wealth of information exists on sub-cellular responses of organisms, primarily birds, mammals, and fish, exposed to these compounds. However, the effects of AChE-inhibiting pesticides at the whole-organism level, most importantly effects relevant to an individual's fitness, have received less attention. My Master's research focused on describing the effects of carbaryl, an AChE-inhibiting pesticide, on several fitness-related traits in the western fence lizard (Sceloporus occidentalis). Reptiles are the least studied vertebrate taxon in ecotoxicological studies even though contaminants are suspected in contributing to recent population declines. Using multiple dose concentrations within the range expected to occur in nature (based on EPA application rates and published pesticide residues on insects), I quantified the effects of carbaryl on sprint performance energy acquisition, and energy allocation, traits which could have important implications for the animal's ability to avoid predators, capture prey, and grow and reproduce. I found that at the highest dose concentration, lizards experienced a decrease in arboreal and terrestrial locomotor performance, a decrease in energy acquisition, and alterations in energy allocation. My findings suggest that acute exposure to high concentrations of carbaryl can have important sublethal consequences on fitness-related traits in S. occidentalis. Future studies should examine the consequences of multiple-pulse exposures to AChE-inhibiting pesticides on reptiles. / Master of Science

The early developmental environment has a profound influence on an individual's life history trajectory and parents have tremendous influence over this environment. Despite the wealth of research demonstrating that incubation temperature affects a suite of traits important to fitness in reptiles, we are only now discovering that nest temperatures are a defining component of the avian developmental environment. Aspects of the nest environment may be an important and overlooked maternal effect in birds as nearly all birds physically incubate their eggs, thus providing a clear link between parental behavior and the developmental environment of the avian embryo. My research used an interdisciplinary approach, uniting concepts from life history theory, bioenergetics. immunology, and physiological ecology to investigate the importance of incubation temperature to avian phenotype. I found that incubation temperature affects a suite of traits important for future development, survival and reproduction in a species of birds. Using a population of wood ducks (Aix sponsa) that has been the subject of long term studies I investigated the effects of incubation temperature on embryonic developmental patterns and energy expenditure, and body size and condition, stress endocrinology, thermoregulatory performance, and immunocompetence in hatchling wood ducks. In all experiments freshly laid wood duck eggs were collected from nest boxes located in SC, transported to Virginia Tech and incubated at one of three temperatures (35.0, 35.9, 37.0Ë C) that fell within the range of naturally-incubated wood duck nest temperatures. I found that less than 1Ë C differences in incubation temperature affected duckling growth and body condition, stress endocrinology, immune responses, and energy expended to thermoregulate. Many of these effects persisted days to weeks after hatching. In most cases, ducklings that hatched from eggs incubated at lowest temperature performed poorer than ducklings that hatched from eggs incubated at the higher temperatures. Incubation temperature also affected wood duck embryonic developmental trajectories and energy expended during incubation with embryos from the low incubation temperature expended more energy and developing slower than ducklings incubated at the higher temperatures. Embryonic energy expenditure could contribute to effects observed on hatchling phenotype. Because I demonstrate that incubation temperature affects hatchling phenotypic quality, the variability upon which natural selection acts, my findings have implications for avian ecology, life history evolution and conservation. / Ph. D.

This investigation examined the adequacy of the forage base to meet current demand of piscivores in Smith Mountain Lake, Virginia. Surplus production, or the maximum sustainable supply, of alewife (Alosa pseudoharengus) and gizzard shad (Dorosoma cepedianum) were determined using data on the biomass, growth, and mortality of each species. Mean hydroacoustic alewife biomass from 1993-1998 was 37 kg/ha and mean gizzard shad cove rotenone biomass from 1990-1997 was 112 kg/ha. Mean annual alewife surplus production was determined to be 73 kg/ha and mean annual gizzard shad surplus production totaled 146 kg/ha. Bioenergetics modeling and population density estimates were utilized to derive the annual food consumption (realized demand) of the two most popular sport fish in the system, striped bass (Morone saxatilis) and largemouth bass (Micropterus salmoides). The striped bass population consumed 46 kg/ha of alewife and 27 kg/ha of gizzard shad annually. Largemouth bass ate 9 kg/ha of alewife and 15 kg/ha of gizzard shad annually. Annual consumption by ancillary predators was estimated to be 13 kg/ha of alewife and 35 kg/ha of gizzard shad. Prey supply to predators is limited by morphology, behavior, and distribution. The cumulative effect on prey availability of these three factors, in addition to consumption by other predators, was quantified. For largemouth bass, available supply of alewife and gizzard shad exceeded demand by 20% and 53% respectively. For striped bass, available supply of gizzard shad surpassed demand by 30% but available alewife supply was only 4% greater than demand. Annual demand of all predators was 94% of total available clupeid supply. Striped bass stockings were increased by 50% in 1998 and will remain at this level in the near future. A predator-prey simulation model of alewife and striped bass populations was developed to explore the consequences of increased predator demand. This model incorporated dependencies between alewife abundance and mortality and the mortality, abundance, and growth of striped bass. Model output showed that a 50% stocking increase has a near-zero probability of increasing the mean annual number of legal and citation striped bass in Smith Mountain Lake. / Ph. D.

Annual energy flow and mean annual biocontent of eighteen compartments were determined for a 0.94 ha north central Texas pond ecosystem. Annual primary production was 7,780 kcal m^-2 yr^-2, and community production-to-respiration ratio was 1.49. One-third of annual primary production accumulated on the substrate as silt and sedimentation. Community production, production-respiration ratio, and biocontents of all compartments except aquatic insects were large in summer, small in winter. Biocontents of four trophic levels in the pond were all of the same order of magnitude, approximately 50 kcal m^-2. Suspended and benthic organic material forprimary consumers and terrestrial insects for tertiary consumers were substantial allochthanous energy imports into the pond system.

Ingestion, assimilation and egestion rates of different sized filter-feeding blackfly larvae Simulium medusaeforme/hargreavesi (Diptera: Simuliidae) were determined. The effects of food type, food concentration and larval size on ingestion rates were tested. These bioenergetic parameters were used to obtain an indication of the importance of blackfly larvae in processing of particulate organic matter in the Buffalo River. Mean ingestion rates for S. medusaeforme/hargreavesi larvae feeding in the field ranged from 900 - 1600 μg/mg/h compared with those for larvae feeding in the laboratory on the same food type (260 - 680 μg/mg/h) and on algae, Chlorella sp. (590 - 1110 μg/mg/h) and Selenastrum sp. (340 - 1140 μg/mg/h). Ingestion rates obtained in this study were much higher than those reported by previous workers. These high ingestion rates are thought to be related to the low organic fraction of the suspended solids in transport in the Buffalo River. Larger larvae were found to ingest between three and six times as much food as smaller larvae. Ingestion rates were affected by the presence of nematodes and by imminent pupation. Assimilation rates on algae ranged from 2.3 - 49.0 μg/mg/h and were comparable with results of previous workers. The low assimilation efficiencies obtained for larvae feeding on algae (0.4 - 15.1 %) are due to the high ingestion rates. From a survey of the Buffalo River larvae were found to ingest between 0.00011 - 0.15 % of the suspended solids per metre of stream bed, about 1 - 7 times more than what has been reported by other workers. In the upper reaches of the Buffalo River larvae were potentially able to ingest all the suspended solids in the size class 0 - 250μ.m within a distance of 3.2km. Blackfly larvae play an important qualitative role in the functioning of a river system as they remove seston from transport and facilitate the action of gut microflora. Blackfly larvae in association with micro-organisms and other invertebrates are responsible for the majority of the retention and mineralisation of organic matter in the river

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No description available.

The bacterial flagellar motor is one of the few rotary motors found in nature, and an excellent example of a complex molecular machine. Flagellar motors in the model organism Escherichia coli are products of the coordinated expression of ∼50 different genes. The E. coli flagellar motor is powered by the proton-motive force (pmf), an electrochemical gradient across the cell membrane. Motor torque is gen- erated by proton flow through membrane-embedded stator units which bind to the basal body of the motor. This thesis aimed to investigate the relationship between the pmf and the flag- ellar motor. A novel pmf control system was developed, based on the light-driven proton pump proteorhodopsin (pR). This system enabled pmf -dependent changes in motor behaviour to be precisely monitored in vivo. Expression of pR in E. coli was shown to be sufficient to drive the flagellar motor at wild-type speeds. Using the pR-based pmf control system, the motor was shown to respond to changes in pmf on a timescale of milliseconds. Surprisingly, motor speed increase was observed when pmf was increased above the physiological norm. Reduction of pmf to low levels enabled individual steps in motor rotation to be observed. Motor response to loss of pmf was investigated. Motors were shown to exhibit a two-stage speed decrease after disruption of pmf , with motor speed falling to ∼20 % of its initial value within milliseconds, reaching a complete stop after 1 s. Extended periods of pmf loss was shown to lead to disengagement of stators from the motor, with motor speed increasing in a stepwise fashion after pmf restoration. The integrity of the motor at different pmf levels was investigated by using TIRF microscopy to directly image positioning of fluorescently tagged motor components. The stator protein MotB was shown to physically leave and rejoin the motor after pmf disruption and restoration, with MotB dispersal following motor stop.

Arctic Cod, Boreogadus saida (Lepechin 1774) occur throughout the circumpolar north at all levels of the water column depending on their life history stage, the time of day, the season, and their activity. Arctic Cod are the most abundant fish species in the Canadian Beaufort Sea (CBS) ecosystem, and are an important link in the flow of energy within the food web. This study examined differences in energy acquisition and usage in Arctic Cod among three depth zones in the CBS (from 15-800m) by examining stomach contents and physiological indicators, taking into account sex, age and body size. Nonparametric comparison analyses found no differences with depth, but support for an ontogenetic shift in diet regarding prey size, a difference in energy content of an average diet between size classes 1 (30-60mm) and 2-4 (2: 60-90mm; 3: 90-120mm; 4: >120mm), and a slight positive relationship between physiological indicators and body size. / October 2016

Background: Heart transplantation remains the gold standard for end-stage heart failure, with current ex vivo organ storage times limited to 4 to 6 h before critical tissue damage occurs. Many preservation solutions exist in an attempt to limit both ischemic and reperfusion damage. In order to compare the effects of various storage solutions, mitochondrial function can be used to provide a sensitive analysis of cellular metabolic function. Methods: Experimental plates were seeded with cardiac myoblasts and kept in suspended animation for either 4 or 8 h at either 4(o) or 21 degrees C, in Celsior (R), Perfadex (R), or Somah storage solutions. Cells were then reanimated for 1 h at 37 degrees C to simulate a reperfusion or clinical transplant scenario. Cellular bioenergetics were measured immediately thereafter to examine biochemical differences between preservation solutions and their effectiveness on preserving metabolic function. Results: The oxygen consumption rates of Somah solution were significantly higher than Celsior (R) and Perfadex (R) at 4 degrees C, with the exception of Perfadex (R) at 4(o) for 4 h. This effect was sustained up to 8 h. At 21 degrees C, oxygen consumption rates of Somah solution are significantly higher than Celsior (R) and Perfadex (R) at basal conditions after 4 h, but this effect is not sustained after 8 h. Conclusions: The purpose of this experiment was to study the efficacy of various preservation solutions on a mitochondrial level. The significantly higher oxygen consumption rates of Somah at 4 degrees C suggests that Somah solution may have the ability to protect cellular mitochondrial integrity, improve transplanted organ function by reducing ischemic-reperfusion injury, and thereby improve transplant outcomes. Given that Somah offers benefits over Celsior (R) and Perfadex (R) at 4 degrees C, it should be a target in future organ preservation solution research.