It is well established that the neurotransmitter serotonin participates in the control of sexual behaviour in the male rat. Recently, it has been found that serotonergic activity may either inhibit or facilitate sexual behaviour, depending on the subtypes of serotonin receptors involved. However, the participation of 5-HT2 receptors in the control of male rat copulation has received little experimental attention, and the published data are equivocal. In Experiments 1-4, it was established that the 5- HT2/1C agonist DCI inhibits sexual behaviour in male rats; this inhibition is effectively reversed by the antagonists ritanserin, pirenperone, and ketanserin. Comparison of these effects , with reference to the binding profiles of each drug, provided strong evidence that 5-HT2/1C receptors mediate an inhibitory influence on sexual behaviour in male rats. In addition, a tentative claim may be made that the effects of these drugs may be more attributable to 5-HT2 activity than 5-UT1C activity. ‘Wet dog shake’ behaviour in rats is known to be 5-HT2- dependent. Experiments 5—7 evaluated the novel proposition that the incidence of spontaneous wet dog shaking (WDS) by male rats in mating tests may provide a behavioural assay of concurrent 5—HT2 activity. WDS was found to be associated with copulatory inhibition in noncopulating males, compared to normal copulators, and this relationship was specific to mating situations. Activating 5-HT2/1C receptors with DOl simultaneously induced WDS and inhibited copulation. Thus, the incidence of spontaneous WDS in untreated males may reflect the function of a 5—HT2—mediated neural mechanism that tonically inhibits copulation in male rats. In Experiment 8, DOl microinjection in the nucleus raphe obscurus/inferior olivary complex also induced WDS and inhibited copulation. This suggests that the hypothesized 5- flT2-dependent inhibitory mechanism is vested in the ventromedial brainstem. Recent anatomical findings support this suggestion: cells in this region have bifurcating axons, projecting collaterally to both the medial preoptic area (implicated in sexual behaviour) and to the ventral cervical spinal cord (implicated in WDS). Overall, the results of the eight experiments provide strong evidence that 5-HT2 receptors mediate some of the inhibitory effects of serotonin on male rat sexual behaviour. / Arts, Faculty of / Psychology, Department of / Graduate

A dynamic model in which multiple consumers of a single nutrient may coexist in a fluctuating environment is given. Only one consumer can persist in a fixed environment, but coexistence may be produced by effects of a fluctuating environmental variable on nutrient utilization differing between consumers. An approximate solution is given for the non-autonomous Lotka-Volterra-Verhulst ordinary differential equations of the model together with heuristic sufficient conditions for construction of a persistent multispecies consumer community. Computational examples demonstrate persistence of an idealized example community for periodic and random environmental fluctuation. Two further examples demonstrate that environmental fluctuation can produce coexistence when environmental variables, standing crops, assimilation efficiencies, primary productivity, utilization rates, and respiration rates are comparable to a tropical grassland, and an oligotrophic temperate lake. The sensitivity of model solutions to functional variations of the component species may be rapidly and accurately calculated. This allows the identification and estimation of unknown species functional responses from time series data of biomasses and a measured environmental variable. Unknown functions of an environmental variable are approximated by a Tchebycheff polynomial expansion in that variable. Unknown coefficients of these expansions are the parameters of the model. These parameters are determined by the unconstrained minimization of the squared deviations of the logarithm of biomass observations and model differential equation solution using a Quasi-Newton algorithm. This least squares estimator was applied to a one year biomass time series of four zooplankton grazers, phytoplankton, and average lake temperature of a small oligotrophic lake. Application of the model to this grazer zooplankton community gives evidence of partial stabilization due to environmental fluctuation in a natural community. It is concluded that environmental variation, which is often assumed on theoretical grounds to be destabilizing, should rather be considered as one of the bases of community persistence. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

This study was undertaken to investigate the ultra-structure, cytochemistry and maturation changes of mink spermatozoa which are important in biological research and in their relevance to artificial insemination. Mature standard dark mink were used in this study. Spermatozoa were released from the testis and epididymis (caput, corpus and cauda) of the male mink, and were also collected from the vagina of female mink immediately after mating. Conventionally prepared thin sections were observed under a transmission electron microscope. Enzymes were cytochemically localized in spermatozoa. The mink spermatozoon head showed six swellings on the dorsoventral aspects: two connected hump-like structures at the anterior border of the equatorial segment of the acrosome, and one at the postacrosomal sheath on each side. These swellings, which show a strong acid phosphatase activity, appeared to be a species-specific structural feature which might be necessary for the recognition of the ovum or for sperm-ovum attachment in fertilization. The occurrence of the postacrosomal swelling in spermatozoa was significantly increased (p < 0.01) during the passage of spermatozoa through the reproductive tract. Although the total length of the head did not change significantly during the passage of spermatozoa down the reproductive tract, the anterior acrosomal length was significantly decreased (p < 0.001), while the postacrosomal length was significantly increased (p < 0.05). The cell membrane on the peripheral part of the acrosome, with the exception of the tip of the acrosome, was significantly separated (p < 0.05) during the passage of spermatozoa through the reproductive tract. The neck appeared to show dorsoventrally continuous but laterally separated capitulum which was followed by two major and five minor columns, forming at first a striated ring and then joining with the dense fibers.of the axial fiber bundle. Some axoneme remnants were found in the interior of the column bundle. The shape of the annulus was triangular in longitudinal sections. The occurrence of the cytoplasmic droplet was significantly decreased (p < 0.001) during the passage of spermatozoa through the test is and epididymis. The motility of spermatozoa was significantly increased (p < 0.05) as spermatozoa passed the successive parts of the reproductive tract. The activities of acid and alkaline phosphatases, ADPase, ATPase and DOPA oxidase were found to be distributed in the head, middle and principal pieces of epididymal spermatozoa. Glucose-6-phosphatase, 5-nucleotidase, non-specific esterase, malate, succinate, lactate and isocitrate dehydrogenases, and NADH diaphorase activities were seen to be confined to the middle piece, while the esterase and malate dehydrogenase activities extended to the head base. The activity of 6-phosphogluconic dehydrogenase was not detected. Although most enzyme activities of spermatozoa were enhanced during the passage of spermatozoa through the reproductive tract, several enzyme activities (acid and alkaline phosphatases, ADPase, ATPase, and malate dehydrogenase) were distinctly reduced in spermatozoa from ejaculated semen recovered from female mink following mating. The presence of enzyme inhibiting factors in the seminal plasma or female reproductive tract was discussed. / Land and Food Systems, Faculty of / Graduate

The tumor-suppressor gene, TP53, plays a major role in surveillance of cellular and genomic integrity, functioning in cell cycle regulation, repair of damaged DNA, and deletion of malfunctioning or defective cells. The latter is achieved through apoptosis, a mechanism of programmed cell death, which is important in both normal morphogenesis and suppression of tumorigenesis. The loss of p53 function in breast cancer has been the subject of intensive study, however, not much is known about how p53 functions in the normal mammary gland to mediate its protective apoptotic responses. The aim of this dissertation was to examine p53-mediated cell death in the murine mammary epithelial cells in response to two distinct apoptotic stimuli: exposure to ionizing radiation and detachment from an appropriate substratum. The first component of this work examined the role p53 plays in mediating apoptosis in response to gamma-radiation during distinct stages of post-natal mammary gland. The second part of this dissertation focused on whether detachment of epithelial cells from their extracellular matrix results in cell death that is p53-dependent or -independent. Results from these experiments demonstrate a requirement for functionally active p53 in radiation-induced cell death, and show that the proliferative capacity of the mammary gland at time of radiation exposure predicts the robustness of this apoptotic response. In contrast, detachment from substratum can trigger both p53-dependent and -independent cell death in mammary epithelial cells. However, apoptosis induced by the specific abrogation of β1 integrin-ligand interaction appears to proceed through a p53-dependent mechanism.

The purpose of this study was to investigate the effects of selective isotonic muscle fatigue upon the neuromuscular coordination control mechanisms underlying ballistic limb movement in males and females. Eight males and eight females served as subjects and were tested across eight days which involved the monitoring of three inertial load conditions (L0 = no load, L1 = 1.5, L2 = 3.0 $\times$ moment of inertia) of a Class B, ballistic forearm flexion movement. Following the first three practice days, selective isotonic muscle fatigue was imposed at one of two intensities, high (6RM) or low (20RM) resistance, in either the agonist (biceps brachii) or antagonist (triceps brachii) muscle group. Exercise days involved pre and post testing of the movement task interspersed by fatiguing isotonic resistance exercise. Kinematic, temporal and quantitative integrated electromyographic pattern and strength measures were analyzed. All measures were reliable (R = 0.14-0.98). Eight days of practice generated significant decreases (p $<$ 0.05) in movement time (MVT). Males exhibited a larger decrease across days (L0 = 14.9%) as compared to females (L0 = 4.7%). Although, males generated a 25% faster MVT than females, both sexes demonstrated a similar reduction in MVT improvements as inertial loading increased. Practice effects manifested in agonist and antagonist temporal pattern measures were pronounced. Several substantial sex differences persisted following the eight days of practice. Antagonist delay (T2D) was significantly (p $<$ 0.05) shorter (32.9%) in males. Across days, males reduced this delay (13.5%) while females exhibited a large (43.2%) increase. The increase in T2D exhibited by females represents an uncoupled temporal association between the decelerating action of the antagonist and the point of maximum acceleration. This modification contributed to the comparatively small improvements in MVT displayed by females across days; explaining the MVT differential observed between the sexes. Low resistance (20RM) selective isotonic muscle fatigue generated the largest decrease in maximum isometric strength (13.6%-21.1%) with low resistance (20RM) flexion fatigue increasing MVT to the greatest extent (15.6%). Males responded more dramatically to isotonic muscle fatigue. However, comparisons of fatigue modifications in neuromuscular coordination control mechanisms between the sexes warrants caution due to the persistent sex differences observed in stabilized performance.

It is the purpose of this research to explore the role that animals played in both the life and writings of Lord Byron. The first areas of concentration are on the specific examples of Byron's affection for animals and on the psychological aspects of this love. Secondly, the thesis attempts to explore the symbolic importance of animals in relation to Byron and his works. Finally, the research is focused on Byron's concepts and ideas, which he frequently illustrated and clarified by animal symbolism.

The topic that I have been studying for this thesis concerns the locomotion of quadruped animals. More specifically, my goal was to study how quadrupeds, such as canines or felines, move and then compare that movement to individuals of the same species, except adding in a factor such as a limp or the removal of an entire limb. I wanted to see how that affected their balance and their gait among other things. Luckily, there are plenty of resources out there for me to study the differences. Between videos online, living with dogs and cats at home, and semi-regularly volunteering at an animal rescue sanctuary, I have been able to amass a sizeable amount of data to determine both how these animals move regularly, and how injuries or the complete loss of a limb affects their movement. I have studied four different types of quadruped walk-cycles and then further studied them to see how various limb injuries affect how they get from point a to point b. Afterwards, I applied what I learned by animating a cycles that capture how the quadruped normally moves and then also animating a cycle where the quadruped has limited ability with one of its limbs.

This study’s purpose was to describe the disaster preparedness of licensed private veterinary practitioners in Mississippi. A mail survey was distributed assessing disaster training, response plans, and disaster-related organization knowledge. Individuals who have experienced a disaster are more likely to have a personal plan, a clinic plan, or both than those who have not. County residence along the Mississippi Gulf Coast showed 3.62 times likelihood of having a personal plan and 3.09 times likelihood of having a clinic plan than those in other districts. Many veterinarians failed to identify their local emergency management agency as their point of contact in a disaster situation, and few indicated having disaster education materials for their clients. Twenty percent of respondents indicated having obtained formal disaster training. More than two-thirds of respondents were interested in disaster training.

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No description available.