In rodents, there exists a strong interaction between the reproductive and circadian systems. For this thesis the female hamster was used as a model for the study of this interaction. Studies described in chapter II investigated whether the circadian regulation of reproductive processes may be through direct input of the suprachiasmatic nucleus (SCN) to neurons containing estrogen receptor (ER) and/or to neurons containing luteinizing hormone releasing hormone (LHRH). The anterograde tracer Phaseolus vulgaris leucoagglutinin (PHA-L) was applied to the SCN and double label immunocytochemistry for PHA-L and either ER or LHRH was carried out. Both ER- and LHRH-immunoreactive cells show appositions with SCN efferents or with efferents of the subparaventricular nucleus and the retrochiasmatic area. Results suggest that the circadian system can regulate reproductive processes via input to LHRH- and/or ER-containing neurons. Studies described in chapter 111 investigated whether effects of estrogen on circadian rhythms may be exerted through estrogen-binding systems afferent to the SCN. Immunocytochemistry for ER and the retrograde tracer cholera toxin B subunit, after its application to the SCN, demonstrated that some areas contain relatively high percentages of SCN afferent neurons which show ER immunoreactivity. Retrograde tracing results were compared with results of anterograde tracing from some of the sites containing SCN afferents. Furthermore, using a combined retrograde and anterograde tracing technique, SCN input to some SCN afferent neurons was demonstrated. However, no evidence of reciprocity between single ER-immunoreactive cells and the SCN was found. Results indicate the existence of estrogen binding systems afferent to the SCN which might mediate the effects of gonadal steroid hormones on circadian rhythms. Studies in chapter IV analyze the effects of blockade of SCN axonal output by local unilateral application of tetrodotoxin (TTX) on the LH surge. Injections of TTX on either the morning or the afternoon of proestrus were unable to block the LH surge. Results favor the interpretation that the SCN output signal responsible of the circadian gating of the LH surge occurs before the onset of the light period on the day of proestrus.

The skeletal elements of cartilaginous fishes are composed of a thin layer of mineralized tissue, ‘prismatic cartilage’, overlaying a hyaline cartilage core. Cartilage, even with a surface layer of mineralization, is far less stiff and strong than bone. Nevertheless, several species of stingray, including Rhinoptera and Aetobatus, subsist by crushing hard-shelled mollusks and crustaceans in their cartilaginous jaws. The jaws of these stingrays are composed of a previously undescribed form of cartilage. This tissue, ‘trabecular cartilage’, has mineralized struts which run through the central hyaline core. The struts, or trabeculae, are hollow tubes, made of calcified blocks, arranged as in a brick chimney. They serve to prevent buckling and bending of the jaws while prey is being crushed. The struts are present in late term embryos, indicating that feeding on hard prey does not cause them to form. As the animal grows the struts lengthen and thicken though they do not appear to become more numerous. Trabecular cartilage appears to have evolved at the base of the clade containing the hard prey specialists. This clade also includes Manta, a planktivorous species, which retains trabecular cartilage.

One of the key aspects of the immune system is the ability to prime cells by vaccination. The γδ T lymphocytes represent a significant population of cells in the peripheral blood of cattle that have largely been ignored in this regard. Here we have explored the potential for WC1+ γδ T cells to be primed by vaccination. We hypothesize that the γδ T cells that exhibit a recall response in vitro following in vivo priming represent a unique population. Utilizing a Leptospira borgpetersenii vaccine, we examined the recall responses of WC1+ and CD4+ T cells to leptospiral antigen. The WC1+ γδ cells were the major responding population to antigen for the first few weeks following in vivo priming, with the CD4 T cell response only began to overtake them after a booster dose was administered. The primed WC1+ γδ T cells displayed a unique pattern of surface marker expression when stimulated with antigen compared to mitogen-stimulated cells, and which paralleled that observed on the CD4 T cells that responded to antigen. Additionally, chemokine receptor expression was assessed in both ex vivo and antigen-stimulated WC1 and CD4T cells. Ex vivo CD4+ and WC1+ T cells differed with regard to chemokine receptor transcript expression while the antigen-activated cells had very similar patterns of expression. Both subsets expressed genes typical of TH1-polarized cells, but differed with regard to transcripts for co-stimulatory molecules expressed. TCR usage by the antigen-responsive WC1+ γδ T cells from vaccinated animals was evaluated. The antigen-responsive cells had transcripts for several different Vγ and Vδ gene segments with very limited usage of J genes and highly variable CDR3 sequences. These results did not differ greatly from those obtained with nondividing cells or with ex vivo peripheral blood mononuclear cells suggesting little if any enrichment for a specific TCR type. These results support the hypothesis that WC1 + γδ T cells and CD4 αβ T cells that respond to leptospira antigen are likely to differ mainly with regard to how they are activated and the pathogen molecules that activate them, rather than with regard to their effector functions.

Assessments of stress typically involve either point samples (blood or saliva) reflecting a moment in time or state samples (urine of feces) reflecting several hours or a day. Currently, there is no way to assess chronic levels of stress without using repeated sampling procedures which are both time consuming, expensive, and possibly stressful. The purpose of this dissertation was three fold: (1) to develop a more chronic estimate of stress by measuring cortisol concentrations in hair, (2) to determine using this measure, how rhesus macaques responded to the prolonged stress of relocation, and (3) to determine the role of a proposed modulatory protein corticosteroid binding globulin (CBG) in measuring stress. Results demonstrate that cortisol can be quantified in hair and that stress reactivity can also be measured in hair. Rhesus monkeys responded to a major life stress (relocation) with a significant increase in cortisol in both hair and serum and with substantial behavioral changes. CBG concentrations failed to show alteration initially following relocation, however a significant increase was observed one year later. The findings demonstrate the importance of the cortisol/CBG relationship during a prolonged stress paradigm. Our data also provide further evidence that the free cortisol index (cortisol:CBG ratio) may be a better indicator of stress reactivity when compared to the commonly used serum cortisol concentrations.

The frog neuromuscular junction is a unique model that allowed us to selectively remove cellular components from the neuromuscular junction and create preparations with varying degrees of nerve terminal stability. We found further evidence that frog terminal Schwann cells communicate with their cellular partners, as terminal Schwann cells responded with changes in number or morphology as a result of changes in synaptic integrity. Terminal Schwann cells divided at synaptic sites in response to a regenerating nerve terminal. Terminal Schwann cells also had morphological changes in response to changes in status of their cellular partners; they extended processes in response to removal of the nerve terminal. Orientation and length of these processes was profoundly affected by the presence or absence of muscle fiber and nerve terminal. Similar to observations at the mammalian neuromuscular junction, terminal Schwann cells appear to play a role in reinnervation, as frequently regenerating nerve terminals were within the confines of terminal Schwann cells and their processes. I also investigated the organization of actin within preparations with varying amounts of nerve terminal stability, including developing nerve terminals and regenerating adult nerve terminals that were forming either stable or unstable connections. Previously, F-actin stained target-deprived nerve terminals in a ladder-like pattern and was concentrated in the nonrelease domains (Dunaevsky and Connor 2000). I found that β-actin was similarly distributed and localized to the nonrelease domains of nerve terminals at intact neuromuscular junctions. Further, association of actin with these particular domains appeared to be important for nerve terminal stability. As nerve terminals acquired increasing stability during development, they acquired this domain specific distribution of F-actin. Additionally, although synaptic sites with stable regenerating nerve terminal acquired this ladder-like pattern of F-actin, it was very rare for unstable regenerating nerve terminals to do so. I also tested the dynamic nature of F-actin with pharmacological perturbation. F-actin at nonrelease domains was found to be very stable. This stability of the F-actin based cytoskeleton further suggests that F-actin at the nonrelease domains of nerve terminals may play a role in the stability of motor nerve terminals.

Despite a rich fossil record and much attention from paleontologists, the phylogeny of mammalian order Perissodactyla (including extant horses, rhinoceroses, and tapirs) is poorly understood. There are at present no well-supported phylogenetic hypotheses of the interrelationships of perissodactyls, nor has the position of this order among other eutherian orders been established. The main hindrance to this understanding is a lack of thorough and rigorous analysis of characters and taxa. This study attempts to overcome this problem by analyzing characters from all aspects of the skeleton in a broad diversity of taxa for one major perissodactyl lineage, the Tapiromorpha. Studies of interordinal and intraordinal relationships of the Perissodactyla have previously been effectively incompatible, because these two types of studies utilized different types of characters. Interordinal studies focused on cranial and postcranial characters, whereas intraordinal studies relied heavily on tooth morphology. This study focuses on cranial and postcranial osteology. The cranial and postcranial skeleton of a broad range of tapiromorphs is described. These descriptions have two purposes: (1) to identify potentially useful characters for use in a phylogenetic analysis of tapiromorphs; and (2) to provide a reference on tapiromorph osteology that will facilitate the inference of primitive tapiromorph character states for higher-level analyses. Putative tapiromorphs include "tapiroids," rhinocerotoids, and chalicotherioids. Numerous representatives of these groups are compared with other perissodactyls (equoids and brontotheres) and eutherians thought to be closely related to perissodactyls. Cranial and postcranial characters drawn from the afore-mentioned descriptions are combined with selected dental characters in a phylogenetic analysis of tapiromorph genera. For the sake of clarity, higher-level taxonomic groups are defined a priori. The results of the phylogenetic analysis demonstrate that there is no unequivocal evidence for including chalicotherioids or the traditional primitive "tapiroid" Homogala in the Tapiromorpha (as defined here). The analysis supports the close relationship between tapirs and rhinoceroses relative to horses, as well as clades that fulfill the definitions of Tapiroidea and Rhinocerotoidea. The results of the phylogenetic analysis provide the basis for a revised classification of the Tapiromorpha.

Nutrition greatly affects the reproductive success in many insects. Also, previous studies have shown this nutrition-reproduction connection is mediated via endocrine control. In Phormia regina, a proteinaceous meal is essential for egg maturation. Recent discovery of a midgut hormone, from liver-fed P. regina, established a link between feeding and endocrine function which leads to oogenesis. This midgut hormone is the first such insect gut hormone governing oogenesis. Whether or not this hormone is released into the hemolymph, however, is not determined. To demonstrate the existence of the midgut hormone in the hemolymph, hemolymph was partially purified and its oogenesis-stimulating effect tested. A gonadotropic effect was observed in the hemolymph extracts prepared from 5 and 6h post-liver-fed females. The midgut hormone appears to circulate in the hemolymph to reach its target, presumably the brain neurosecretory cells. Injection of partially purified midgut hormone caused a significant volume increase and changes in the distribution of stainable materials of the type-A brain median neurosecretory cells (MNCs). It is conceivable that these cellular changes reflect the synthesis/release of neurohormones by the type-A MNCs. Thus, results suggested that midgut hormone is hemolymph-borne and has a cerebrotropic function. The possible role of the brain after being stimulated by midgut hormone was investigated. In vitro studies showed that the brain releases, at 8h after a protein meal, a factor(s) with a strong allatotropic effect (i.e., causing the corpus allatum (CA) to produce 6.9 times more juvenile hormones (JHs) than the control CA). The characteristics of this allatotropic factor(s) were estimated with different experiments. First, Manduca sexta allatotropin (Mas-AT)-immunopositive substances were observed in the lateral neurosecretory cells (LNCs) and the neurosecretory cells located between the pars intercerebralis and oesophagus foramen. Second, synthetic Mas-AT stimulated JH biosynthesis by the fly's CA (2.64-fold activation when stimulated with 20 pmol per test). Third, when brain-released factor(s) was neutralized with anti-Mas-AT antiserum both in vivo and in vitro, the CA still synthesized a considerable quantity of JH. This result suggested that there may be additional non-Mas-AT allatotropic agent in P. regina.

The fact that physical performance deteriorates concomitantly with the process of senescence is well-documented. However, little is actually known regarding the control mechanisms which induce the physiological dysfunction associated with age. The purpose of this investigation was to evaluate the effect of age on neuromotor coordination mechanisms and fractionated reaction time parameters during the execution of ballistic forearm flexion and extension, maximum voluntary isometric forearm flexion and extension strength and limb volume. A total of 48 male subjects in three age groups were studied (16 in each group): (1) 30-40 years old, (2) 50-60 years old and (3) 61-70 years old. On each of four test days each of the following criterion measures were recorded: (1) two slow and two fast maximum voluntary isometric contractions of the flexors of one arm and the extensors of the other arm, (2) twenty simple reaction time trials of the flexors of one arm and the extensors of the other arm, (3) twenty simple resisted reaction time trials of the flexors of one arm and the extensors of the other and (4) twenty trials of speed of movement at two inertial loads for the flexors of one arm and the extensors of the other arm. A repeated measures analysis of variance was employed to determine which data was the most stable. The analysis that there were few significant differences between the trials recorded on day 1 and day 2, indicating that performance had stabilized. Intraclass correlation analysis showed that the criterion measures were reliable. Age group comparison revealed significant differences between the groups for: (1) maximum voluntary isometric strength, (2) maximum displacement, (3) agonist silent period, (4) accuracy, (5) resisted motor time and (6) resisted total reaction time. A non-significant age-related trend for the following parameters to be adversely affected with age was noted: (1) movement time, (2) agonist first burst motor time, (3) antagonist first burst motor time, (4) antagonist second burst duration, (5) agonist first burst integrated electromyographic slope, (6) antagonist second burst time to peak activity, (7) time to maximum acceleration, (8) agonist first burst peak amplitude, (9) antagonist second burst peak amplitude, and (10) acceleration as a percentage of movement time.

No description available.

Exercise-induced muscle damage may alter the availability of glutamine for cells of the immune system following strenuous exercise. However, little is known about the effects of exercise-induced muscle damage on the immune system. Elevated serum CK activity, an indirect marker of muscle damage, was used as a post-exercise criterion to place subjects who performed the same exercise into High and Low CK groups. The purpose of this investigation was to determine whether (1) the response of plasma glutamine concentration; and (2) cellular components of the peripheral blood, particularly leukocyte numbers and subset proportions, responded similarly to high force eccentric in High and Low CK groups. Twelve female subjects performed high-force eccentric exercise using one arm and one leg, respectively. Blood samples were collected 1 d and 0 h pre-exercise, 0 and 2 h, 1, 2, 3, 5, 7, and 9 d post-exercise and analyzed for serum CK activity, whole blood glutamine concentration, complete blood count, and lymphocyte subsets consisting of T, CD4+, CD8+, B, NK, and IL-2 receptor positive (IL-2R+) lymphocytes. Seven subjects were placed in the High CK group and 5 in the Low CK group. Differences between High and Low CK groups, identified by comparing the positive and negative integrated areas of deviation from baseline, respectively, were not apparent. For all subjects combined into a single group, there was a 13% increase in granulocytes 0 and 2 h post-exercise, 24 and 29% increases in NK cell concentration and proportion of lymphocytes immediately post-exercise, a delayed increase in NK cells 3 and 9 d post-exercise, and 17 to 22% decreases in CD8+ lymphocytes 2, 5, and 9 d post-exercise (p $<$ 0.05 for all). A significant decrease in blood glutamine concentration (p $<$ 0.05) was measured 3 d post-exercise. These changes were either the result of changes at the level of the muscle induced by the exercise, but independent of factors contributing to CK efflux, or the result of as yet unidentified systemic signals initiated by the performance of the exercise.