The Acipenseridae comprises the largest group of non-teleostean actinopterygians and has served a central role in evolutionary studies of the Actinopterygii, and yet no comprehensive study of morphology and systematics of the family has ever been made. The family includes twenty-four species within four traditionally recognized genera, but the traditional generic designations lack rigorous definition within a cladistic scheme and are confounded by plesiomorphic characters. As background, revised diagnoses, synonymy lists, and overviews of life history are provided for every acipenserid species and genus. The systematics of the Acipenseridae are addressed with emphasis on generic-level relationships based on characters from examinations of skeletal morphology. A complete description of the skeleton of the shovelnose sturgeon Scaphirhynchus platorynchus provides a template of the skeleton of acipenserids. Skeletal comparisons with representatives of the remaining three acipenserid genera (Huso, Acipenser, and Pseudoscaphirhynchus), as well as Polyodontidae, $\dagger$Chondrosteidae, $\dagger$Peipiaosteidae, and other actinopterygians were used to identify, define, and test putative synapomorphies. Ninety-six synapomorphies are identified defining all major nodes within Acipenseriformes. A novel phylogeny of Acipenseridae is proposed, with Huso recognized as the sister group to a newly redefined subfamily Acipenserinae comprising all other acipenserids. The shovelnose sturgeons (genera Scaphirhynchus and Pseudoscaphirhynchus) compose a monophyletic Scaphirhynchini. No synapomorphies are recognized defining Acipenser, leaving the genus as a potentially untenable assemblage within Acipenseridae. The proposed phylogeny suggests that evolution within Acipenseridae followed a markedly different course than typically assumed, with progressive increase in morphological specializations for benthic life. Huso and polyodontids (as immediate outgroups) define an outgroup morphology and life history founded on mid-water habitats and piscivory. In contrast, most acipenserines, and more markedly in scaphirhynchines, are more benthic as exemplified by their ventral jaws and substrate-oriented diets. This phylogeny further suggests that peramorphosis, not paedomorphosis, played a central role in acipenserid evolution, exemplified by progressive acquisition of novel bones, increased scalation, and stronger dermal ornament. While putative paedomorphic characters are coincident with these peramorphic characters, addition of characters through peramorphosis belies the historical idea that paedomorphic or degenerate features dominate acipenserid evolution.

The organization of retinal ganglion cell (RGC) axons within the optic nerve (ON), chiasm (OCh), and tract of the frog, Rana pipiens, was examined using both light and electron microscopy. In one group of experiments, anterograde and retrograde transport of horseradish peroxidase (HRP) revealed the spatial reorganizations of RGC axons between the retina and central retinorecipient targets. Optic axons form a concentric representation or map of the retinal surface across the distal ON cross-section. Within this map, the distal ON contains two representations of the temporal and nasal retinal quadrants. Fiber reorganizations within the proximal ON result in axons from central RGCs becoming positioned within the dorsal region of the nerve and in axons of more peripheral RGC becoming localized to the ventral, anterior, and posterior margins of the nerve. As a result of this proximal ON fiber reorganization, age-related RGC axons become grouped in laminae that are aligned perpendicular to the posterodorsal-anteroventral axis of the optic projection. Axons occupying complementary positions in different retinal representations converge in a dorsal-to-ventral sequence as the projection passes through the perichiasm. Within the prechiasm, axons separate from the laminated optic projection to form four fascicles; the projection to corpus geniculatum, the projection to the neuropil of Bellonci, the basal optic root, and the marginal optic tract (MOT). In addition, electron microscopic examination of the optic fiber spectrum revealed the morphological organization of the retinofugal projection within the ON and the lateral division of the marginal optic tract (lMOT). Within the ON, myelinated and unmyelinated axons of various sizes are homogeneously distributed. Optic axons are reorganized within the MOT such that within the lMOT large myelinated optic axons become concentrated within ventromedial regions and small myelinated axons become concentrated within the dorsolateral regions. In rostral lMOT larger unmyelinated axons are also concentrated along the ventromedial regions. The morphological organization of the optic axons within lMOT, established by the reorganization of the retinofugal projection within MOT, anticipates the innervation pattern of the optic axons within the laminated, superficial layers of the optic tectum.

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.

This dissertation's primary objective was to test for heterochronic patterns and processes, specifically paedomorphism and neoteny within a putative ancestral-descendant pair the wolf, Canis lupus and the dog, Canis familiaris . In addition, patterns of developmental and morphological integration were investigated. Three dimensional landmark-based data were collected on an ontogenetic series of over 700 crania belonging to Canis familiaris (100 breeds) and 310 Canis lupus. Morphometric data analysis was accomplished by the following methods: cranial shape centroid and geometric mean differences, ontogenetic allometric regression, common principal component analysis (Flury, 1988), shared correlation matrix structure (SCMS), and Heterochronic Prediction and Diagnosis (Williams, 2001, Williams et al., 2003). Heterochronic processes, including neoteny, do not describe the evolution of most dog breeds examined, although adults of a few breeds are paedomorphic, meaning they exhibit cranial morphology similar to juvenile wolves. However, there is a wide diversity of skull shapes within the globally paedomorphic breeds. Not all dog breed crania conform to the predicted cranial shape expected from a heterochronically derived descendant of Canis lupus. Some breeds' crania are indeed morphological snapshots from wolf ontogeny, having the same shape and size as a juvenile or an adult wolf. Other breeds may have a cranial shape similar to a particular stage in the wolf's ontogeny but, because of the dissociation of size and shape, their crania are not similar in size to those of the wolf at that ontogenetic stage. Still other breeds are neomorphic, i.e. similar to no stage along the wolf ontogenetic trajectory. The evolution of Afghans, Appenseller Sennenhunds, Bernese Mountain Dogs, German Shepherds, Labradors and Newfoundlands is best modeled via the heterochronic process proportioned dwarfism. Chihuahuas are the only small breed well modeled by a heterochronic process of proportioned dwarfism. St. Bernards as well as Fox Terriers, French Bulldogs, and Pugs were not well described by any heterochronic model. During canid ontogeny, pattern and intensity of integration among cranial elements varies and adult and neonatal patterns are each unique. Ancestral patterns of developmental integration do not predict Canis familiaris integration.

Armadillos are fossorial mammals found primarily in South America. Extant genera vary in size, behavior, and habitat. Armadillos use their forelimbs to break the soil when digging; hindlimb use varies. Some use hindlimbs purely for bracing; others actively excavate with their hindlimbs. Use of the hindlimbs in excavation is related to burrow creation. Three armadillo species were examined in the present study: Dasypus novemcinctus, Tolypeutes matacus, and Chaetophractus vellerosus. Dramatic differences were present in both the osteology and myology of the hindlimb. Identification of muscles was a non-trivial task. Among the difficulties was identification of divisions of the gluteus superficialis. This muscle traditionally is divided into the gluteus maximus and femorococcygeus. In armadillos the natural division appears to be tripartite. The hindlimb of Tolypeutes is dramatically different from that of Dasypus. Chaetophractus has a more intermediate morphology, but generally resembles Dasypus. Many anatomical differences appear related to burrowing. Tolypeutes is the least fossorial, but most cursorial of extant armadillos. Both Dasypus and Chaetophractus are accomplished burrowers, and share several features which appear to be specializations for using the hindlimb to excavate soil. The tibia and fibula are more robust in Dasypus than in Tolypeutes. A well developed flange, site of origin for the peronei, is present on the proximal fibula in Dasypus. The tibia-fibula of Chaetophractus is intermediate. The muscles of Dasypus, particularly the gluteals and hamstrings, are better developed than those of Chaetophractus, which in turn, has better developed muscles than Tolypeutes. Two muscles, the caudofemoralis and crurococcygeus, are present in Dasypus, but absent in the other two armadillos. The sartorius and tenuissimus are present in Chaetophractus and Dasypus, but absent in Tolypeutes. Intrinsic pedal musculature is better differentiated and developed in Dasypus and Chaetophractus. Fossoriality has yet to be directly measured in armadillos. Behavioral descriptions have suggested Chaetophractus is more fossorial than Dasypus. Hindlimb anatomy suggests Dasypus is the better burrower. Extending the hindlimb analysis to a controversial fossil armadillo, †Peltephilus, suggests it was not a burrower.

To separate functional from phylogenetic pelvic differences in Aves, seventy-seven birds were measured and statistically analyzed to define the characters that unite them into function groups, and to identify the characters that separate the function groups from each other. Four Major Function Groups were identified: Birds of Prey (Chapter II) Waterbirds (Chapter III), Ground birds and Stalker-wader birds (Chapter V). Birds of Prey statistically separate into Air predators and Scavengers. Waterbirds statistically divide into Surface swimmers, Wing-propelled divers, and Foot-propelled divers. A suite of pelvic characters (Level One indicators) can separate nonpasseriformes birds into function groups. These are: length to width ratio of the pelvis, iliac angle, relative iliac surface areas and pre-acetabular ilium proportions. A second suite of characters (Level Two indicators), used by themselves, shows trends, but do not completely separate the function groups. These are proportional length of lower leg components, and femur length: pelvis length ratio. Combining the identified characters in Principal Component Analysis and Discriminant Function Analysis produces a good split among the function groups. When all of the birds are combined into a single analysis (Chapter V), using Level one and Level Two characters, the plots generated have Stalker-wader birds at the center, with three groups radiating out. One arm is Ground Birds, another is Waterbirds, and the third is Birds of Prey. Pelvic musculature dissections of a representative from each group are compared (Chapter VI). The picture drawn from the muscle data is different. The muscle data suggest that Ground Birds are the central group. Ground Birds (represented by a pigeon) have leg/pelvic muscles neither specialized for specific femoral movements, nor for specific tibiotarsal movements. No particular group of muscles is hypertrophied, and no major groups are reduced or missing. The other three function groups of birds show some degree of specialization, either by reducing or accentuating muscles, or by losing muscles completely. The result is a statistical portrait of four bird function groups that has implications for the sequence of morphological changes seen in avian radiations of the Tertiary.

Recent anatomical and neurochemical studies suggest that the dorsal raphe nucleus (DRN) of the brainstem is composed of several subdivisions that have different afferent and efferent connections and are different neurochemically. In the present study, DRN subdivisions projecting to visual system structures were studied in a highly visual rodent, the Mongolian gerbil (Meriones unguiculatus). In one group of gerbils, the fluorescent neural tract tracer Fluoro-Gold was injected into the superior colliculus (SC), and brain sections also were double-labeled for serotonin (5-hydroxytryptamine, 5-HT). In another group of gerbils, the neural tract tracer cholera toxin subunit B (CTB) was injected into the SC, lateral geniculate nucleus (LGN), or primary visual cortex (V1). The location of retrogradely labeled cells in the DRN was analyzed at five rostro-caudal levels to determine DRN subdivisions projecting to these visual structures. At the three most rostral coronal levels, virtually all cells projecting to the SC occurred in the lateral DRN; most of these cells were serotonergic. At these rostral levels, virtually all cells projecting to the LGN also were observed in the lateral DRN. At the two most caudal levels, retrogradely labeled cells were observed in the ventromedial and interfascicular DRN following tracer injections into the SC or LGN. Following CTB injections into the primary visual cortex, virtually all retrogradely labeled cells occurred in the ventromedial DRN at all rostro-caudal levels. Therefore, the ventral caudal region of the DRN appeared to be the only DRN region projecting to all three visual areas (SC, LGN, and V1). In order to determine whether functional differences might exist among DRN subdivisions, the expression of c-fos, an immediate-early gene, was analyzed in all DRN subdivisions throughout the light-dark cycle. In all subdivisions, the highest c-Fos expression was observed one hour after the onset of the dark period. However, ANOVA analysis revealed that the diurnal variation in c-Fos expression was statistically significant only in the caudal ventral region of the DRN, and gradually became less prominent in the caudal-to-rostral and ventral-to-dorsal directions. A portion of this Dissertation has been previously published in the Journal of Comparative Neurology (Janušonis et al., 1999).

Abstract not available

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.

A recent decline in Atlantic salmon (Salmo salar) populations have led to their listing as an endangered species and is related to the contamination of rivers due to the high application rates of pesticides in agriculture. Four experiments were designed to study the effect of pesticides on several life history stages of Atlantic salmon: (i) yolk-sac larvae (YSL) were exposed for 21 d to sub-lethal levels (<100 μg l-1) of hexazinone (HEX) and atrazine (ATZ) in fresh water (FW). After a year smolts were exposed to 24 h seawater challenge (SW); (ii) smolts were exposed for 21 d to sub-lethal levels (<100 μg l-1) of HEX and ATZ in FW. After 21 d smolts were exposed to 24 h SW; (iii) YSL were exposed for 12 d to 10 μg l-1 of ATZ, HEX, chlorothalonil (CTL), and phosmet (PHO) at pH 6.5 and 5.0; and (iv) YSL were exposed to either 1 or 10 μg l-1 of ATZ, CTL, PHO and HEX or binary combinations of each. We measured the hormones involved in smolt development (cortisol, GH, IGF-I, T4 and T3) and cholinesterase activity in larvae, plasma ions (Cl-, Mg2+, Na+, Ca2+) in FW and after SW challenge, and Na+, K+-ATPase activity at both life stages. In conclusion ATZ causes ionoregulatory, growth and endocrine disturbance and reduces salinity tolerance of Atlantic salmon smolts. Plasma cortisol was affected in smolt exposed to ATZ and HEX as YSL and after a second ATZ exposure. Exposure of YSL to ATZ, HEX and low pH caused faster opercular movement, which suggests a higher energetic demand and/or a respiratory impact. Low pH causes ionoregualtory disturbance in YSL. Low pH and combinations of pesticides causes few synergistic effect and in most cases the effect was additive. Body size was smaller in YSL exposed to low pH and to a combination of pesticides. Disruption of nerve transmission was found in YSL exposed to the insecticide PHO alone or in combination with low pH, ATZ, CTL or HEX. In the wild these impacts may compromise their growth, competitive ability and predator avoidance affecting their survival and population recruitment.