Genetic variation and thermal tolerance were surveyed for variation attributed to nonuniform selection pressures for five populations of the red shiner, Notropis lutrensis, collected from regulated and unregulated portions of a Texas river. Populations within 30 km of a hypolimnion-release dam that experience large thermal perturbations were found to have higher levels of heterozygosity, higher levels of polymorphism, significantly depressed levels of upper thermal tolerance endpoints, and greater variances in tolerance endpoints. These populations have evolved enzyme systems differing from the unregulated populations in response to a variable and depressed thermal regime.

Hazard assessment of pesticides in aquatic environments requires accurate predictions of persistence and compartmentalization. A strategy for developing confidence in predictive fate models, such as the Exposure Analysis Modeling System (EXAMS) and the Simplified Lake and Stream Analysis model (SLSA), is to test the models using carefully chosen chemicals in semi-controlled and field situations. An objective of this approach would be to isolate the variability in a particular fate process and thereby assess the ability of an algorithm to model the process. For example, endothall, a relatively watersoluble aquatic herbicide, has essentially a sole fate process, biotransformation. Endothall was used to test the predictive capabilities of EXAMS and SLSA and to identify sources of variance in those predictions.

Observed and expected heterozygosity (H) levels for ten electrophoretic blood marker loci and expected H for seven red blood cell (RBC) anitgen/antibody loci were examined for 20 years in American Standardbred and 30 years in American Saddlebred horses. Standardbreds were classed by gait, Trotter and Pacer, and evaluated separately in most analyses. 4,404 Trotters and 12,271 Pacers were found to have statistically highly significant losses of mean total observed H through time for the ten electrophoretic loci (P<0.005), although in Trotters the loss was more extreme (P<<0.001). Loss of H in 5984 Saddlebreds was not significant (P=0.259). Correlations of RBC expected H through time showed decreases in all three groups.

Seventy-one aquatic species including the copepodids and nauplii were identified from Lake Texoma from August 1996 to September 1997. Zooplankton community structure, abundance and spatial and temporal distributions were compared among five lake zones delineated a priori based on chloride concentration. The zones, in order of decreasing chloride concentration, are the Red River zone (RRZ), Red river Transition zone (RRTZ), Main Lake zone (MLZ), Washita River Transition zone (WRTZ) and Washita River zone (WRZ). Bray Curtis Similarity Index showed community structure was most similar in the two Red River arm zones, the two Washita River arm zones and the MLZ. Zooplankton abundance was greatest in the Red River arm (312 org/L), intermediate in the Washita River arm (217 org/L) and least in the Main Lake body (103 org/L). A significant increase in the abundance of a deformed rotifer, Keratella cochlearis, was observed mainly in the Red River arm during a second study from March 1999 to June 1999. Seasonal dynamics, rather than spatial dynamics, were more important in structuring the zooplankton community, especially in the two river arms. Spatial variance was solely attributed to station and zone effects independent of time for a few crustacean species and many of the …

Baroreflex function and cardiovascular responses to lower body negative pressure during selective autonomic blockade were evaluated in endurance exercise trained (ET) and untrained (UT) men. Baroreflex function was evaluated using a progressive intravenous infusion of phenylephrine HCL (PE) to a maximum of 0.12 mg/min. Heart rate, arterial blood pressure, cardiac output and forearm blood flow were measured at each infusion rate of PE. The reduction in forearm blood flow and concomitant rise in forearm vascular resistance was the same for each subject group. However, the heart rate decreases per unit increase of systolic or mean blood pressure were significantly (P<.05) less in the ET subjects (0.91 ± 0.30 versus 1.62 ± 0.28 for UT). During progressive lower body negative pressure with no drug intervention, the ET subjects had a significantly (P<.05) greater fall in systolic blood pressure (33.8 ± 4.8 torr versus 16.7 ± 3.9 torr). However, the change in forearm blood flow or resistance was not significantly different between groups. Blockade of parasympathetic receptors with atropine (0.04 mg/kg) eliminated the differences in response to lower body negative pressure. Blockade of cardiac sympathetic receptors with metoprolol (0.02 mg/kg) did not affect the differences observed during the control test. It was …

This study investigated whether acute myocardial ischemia of the anterior left ventricular wall induced an increase in cardiac sympathetic efferent nerve activity and thereby affected regional myocardial blood flow and contractile function.

Previously, Whipp et. al. (J. Appl. Physiol.: Respirat. Environ. Exerc. Physiol. 50(1):217-221, 1981) demonstrated the feasibility of determining four parameters of aerobic function, identified as maximum oxygen uptake (μVO_2), VO_2 at anaerobic threshold (θan), the time constant for oxygen uptake kinetics (rVO_2) and work efficiency (η), using a short duration ramped bicycle ergometer exercise test. Because of the importance of being able to measure these parameters on a variety of measurement instruments a short duration ramping treadmill protocol has been developed. The ability of this protocol to determine the four aerobic parameters has been validated against conventional methods. The results of this investigation indicate that μVO_2, θan, rVO_2 and, η may be obtained from a single, short-duration ramping treadmill test.

The toxicity of methanol, atrazine, and copper to Pseudokirchneriella subcapitata (Korshikov) Hindák historically referred to as Selenastrum capricornutum Printz were determined following 96 hrs growth in a modified Goram's growth media. Methanol and atrazine inhibited fluorescence readings in the cultures by 50% (IC50) at concentrations of 2% and 82 µg/l respectively. These toxicity values compared favorably to other published reports. The IC50 for copper was 160 µg/l which is substantially higher than reported values. This is understandable because of the high chelating capacity of Goram's media. The use of stereologically derived relative volume in the chloroplasts, mitochondria, lipid bodies, phosphate bodies, and nucleus was investigated to determine if it could be used as a sensitive endpoint in toxicity tests. The volume fractions for the chloroplasts and mitochondria were normally distributed in control cells while the nuclei, phosphate bodies, and lipid bodies were not. The chloroplasts were the most dominate organelle occupying a mean relative volume of 46% and mitochondria occupied a mean relative volume of 3%. The nucleus and phosphate bodies occupied a median relative volume of 7% and 2% respectively. The lipid bodies were rare in section profile and no meaningful median relative volume could be calculated. Up to …

Crocodilians and birds comprise sister taxa of archosaurs, the development of these vertebrates occurs within an egg case that leaves developing embryos susceptible to fluctuations in the nesting environment. Studies suggest that sub-optimal conditions alter morphological growth and cardiovascular physiology. Regulation of the cardiovascular system is immature in the subjects studied, and embryos may rely on humoral rather than neural control of the cardiovascular system. The primary focus of this dissertation was to assess regulatory mechanisms responsible for maintenance of arterial pressure and heart rate. Dehydration stress had marked effects on embryo growth, and altered baseline cardiovascular parameters, while leaving the response to humoral regulator, angiotensin II (Ang II), unaffected. However, dehydrated alligator embryos developed cholinergic tone on heart rate. Hypoxic incubated chicken embryos were reduced in embryo mass, and altered response to humoral regulatory components Ang I and adenosine in addition identifying a novel regulatory component of the cardiovascular response to acute hypoxia. Collectively, these studies add to the existing knowledge of cardiovascular physiology in embryonic archosaurs and suggest that some components of cardiovascular regulation are plastic following developmental stress.

Principal objectives of my research were to: (1) report for the first time that coelomocytes are able to reduce NBT dye and confirm the presence of lysozyme-like activity in earthworm; (2) develop a standard methodology for determination of NBT reduction and lysozyme-like activity in earthworms; (3) compare NBT reduction and lysozyme-like activity in earthworms with those of murine and human cells and fluids; and (4) demonstrate the sensitivity of earthworm NBT reduction and lysozyme-like activity as the assays using matrics in refuse-derived fuel fly ash (RDFF) and CuSO4.

The effects of moderate workload exercise at different pedal rates on circulatory and respiratory parameters were studied. Five subjects performed seven discontinuous constant-load cycle ergometer tests of 30 minutes duration at pedal rates of 40, 50, 60, 70, 80, 90 and 100 rpm. Oxygen uptake and carbon dioxide production were determined by standard open circuit spirometry, while heart rate was recorded by electrocardiograph. The CO₂ rebreathing procedure was administered during the exercise bout in order to determine cardiac output. Blood pressure was determined for each test, and total peripheral resistance was calculated. The findings indicate that progressive increases in pedal frequency during discontinuous constant-load cycle ergometry produce progressive increases in cardiovascular, respiratory and metabolic responses and a decrease in gross exercise mechanical efficiency. The results indicate that oxygen uptake, cardiac output, heart rate, ventilation and arterial-venous oxygen difference increases curvilinearly as pedal rate increases, possibly as a result of increases in recruitment of muscle fibers and/or muscle groups. These findings suggest that circulatory and respiratory responses are due to "central command" which sets the basic efferent response pattern. However, this effector pattern is modulated by afferent input originating from the legs during progressive increases in pedal rate.

When Y-1 mouse adrenal tumor cells were treated with sodium orthovanadate, an intermediate filament (IF) inhibitor in BHK21-F cells, there was no change in the amount of 20α-dihydroprogesterone produced. A neurofilament inhibitor, β, β'-iminodipropionitrile (IDPN), enhanced the ability of Y-1 cells to produce steroid in response to ACTH by acting on the plasma membrane. Electron microscopy of Y-1 cells extracted with Triton X-100 revealed that both vanadate and IDPN caused the aggregation of cytoskeletal and granular structures in the perinuclear area. The steroidogenic effects of IDPN suggest that the perinuclear aggrergation of cytoskeletal structures may result from the detachment of IF from the plasma membrane, while the reason for the cytoskeletal changes by vanadate is unknown.

The evolutionary relationships of woodrats (Neotoma) were elulcidated through phylogenetic analyses of mitochondrial DNA restriction site and allozyme data. DNA samples from eleven nominal species from the genus Neotoma and two outgroup taxa, Ototylomys phyttotis and Xenomys nelsoni, were cleaved using a suite of 17 Type II restriction endonucleases. Mitochondrial DNA restriction profiles were visualized following electrophoresis of restriction digests via methods of Southern transfer and hybridization with 32P- and digoxigenin-labeled mtDNA probes. Restriction mapping resulted in the identification of 37 unique mtDNA haplotypes among the woodrat taxa examined. Proteins representing 24 presumptive structural gene loci were examined through starch gel electrophoresis. Binary-coded allozyme data and allozyme frequency data were analyzed using PAUP and FREQPARS, respectively. Phylogenetic analyses of the mtDNA restriction site data incorporated three different character type assumptions: unordered binary characters, Dollo characters, and differentially weighted unordered characters employing the STEPMATRIX option of PAUP. Proposed phylogenies for Neotoma are based on majority-rule consensus trees produced using bootstrap procedures. Phylogenetic analyses of the woodrat data sets revealed a distinct dichotomy among populations of white-throated woodrats (N. albigula) suggesting the presence of cryptic species within that taxon. MtDNA and allozyme data support the specific status of N. devia as distinct …

The life history and ontogenetic microhabitat change of Mayatrichia ponta Ross were investigated in Honey Creek, Turner Falls Park, Murray Co., Oklahoma, U.S.A. from August 1994 to August 1995. The shape of larval cases changed from a small cone to a cylinder. M. ponta had an asynchronous multivoltine life history with considerable cohort and generation overlap; five generations were estimated. The development rate was reduced in winter. The winter generations of M. ponta had wider head capsule widths (136-165 μm) than summer generations (121-145 μm). The sex ratio of adults was 1.43 ♂ : 1 ♀. Fecundity ranged from 46 to 150 eggs/female. Fifth instar larvae and pupae aggregated on the bottom side of substrates. Early instars were distributed evenly on all sides of substrates. General patterns of ontogenetic microhabitat shift in aquatic insects are categorized as flow mediated, flow independent, and population interactions and other resources mediated.

In adult vertebrates, cardiovascular regulation is accomplished by numerous systems with neural, hormonal and local components responsible for the majority of regulation. These regulatory components work in concert to maintain the essential function of blood perfusion to adult tissues. Given the essential nature of this function it is therefore surprising that the development of cardiovascular regulation during gestation is poorly understood. The majority of what is known is based on a single vertebrate model, the fetal lamb. The fetal lamb has been used in multiple studies due to the clear clinical applications and has been pivotal in understanding the onset of regulation in developing vertebrates. However, study on the fetal lamb is limited to the latter 40% of gestation and has the added complication of an in-utero developmental strategy. Therefore the primary focus of this dissertation was to characterize basic cardiovascular regulation in the chicken embryo to provided the needed information for it's use an alternative to the fetal lamb. Developing chicken embryos rely on both alpha and beta adrenergic tones to maintain normal heart rate and arterial blood pressure during incubation. However, on day 21, just prior to hatch, these animals lose both tones on arterial pressure suggesting the …

The underwater optical climate of Lake Texoma was measured at eleven fixed stations from August 1996 to August 1997. Secchi transparency and submarine photometry characterized seasonal and spatial values of secchi depth (SD), vertical attenuation coefficient (η''), and depth of euphotic zone (Zeu). Indices of Zeu:SD and η'' × SD were compared with universally applied values derived from inland and coastal waters. Turbidity explained 76% of the variation (p = 0.0001) of η'' among water quality parameters, including chlorophyll-α. Using a spectroradiometer, spectral signatures of chlorophyll-α and turbidity were located. Stations with low turbidity exhibited a distinct green reflectance peak around 590-610 nanometers, indicating presence of chlorophyll-α. Stations with high turbidity exhibited a reflectance peak shift towards the red spectrum, making it difficult to detect the chlorophyll signature. Derivative analysis of the reflectance signal at 590-610, and 720-780 nanometers allowed discrimination of this chlorophyll signature from those of turbidity (0.66 ≤ r^2 ≤ 0.99).

Macroinvertebrates associated with the aquatic plant, water stargrass (Heteranthera dubia), were sampled from 12 waterbodies in four regions of the United States from June to August 2005. Taxa richness, evenness, and diversity were lowest in the Lower Midwest (LMW) region, and higher in Northern sites, especially the Upper Midwest (UMW), and Northeast (NE). While relative abundance varied from site to site and region to region, utilization of the plant by functional groups remained fairly constant. Collector-gatherers consistently comprised the largest portion of invertebrates sampled. The shredder/ herbivore functional group comprised an average of 17 % of total groups. Through an exhaustive literature review, it was found that shredder/ herbivores of water stargrass have not been reported in the literature. Because of this, the herbivore group was analyzed separately and consisted of 2,383 specimens representing 23 species. The most common groups were Rhopalosiphum sp., Nectopsyche spp. and chironomids. No differences were found in herbivore diversity or evenness between sampling regions, but species richness was significantly different.

A research program was developed to investigate basic and applied aspects of toxicity, both lethal and sublethal, of hemoxidants, particularly nitrite, on fish, non-fish aquatic vertebrates, and crayfish. The major objectives of this research were to determine A) acute and sublethal toxicity of nitrite to selected aquatic organisms: 1. aquatic salamander larvae, Ambystoma texanum, 2. swamp crayfish, Procambarus simulans, 3. bluegill, Lepomis macrochirus, 4. bullfrog, tadpoles, Rana catesbiana, 5. channel catfish, Ictalurus punctatus, B) the influence of environmental chloride on acute and sublethal exposures to hemoxidants: 1. on acute nitrite toxicity to salamander larvae, crayfish, and bluegill, 2. on nitrite-induced methemoglobinemia in bullfrog tadpoles, Rana catesbian, C) the effect of environmental hydrogen ion concentrations (pH) on acute nitrite toxicity 1. to the crayfish, Procambarus simulans, 2. to the bluegill, Lepomis macrochirus, D) the effect of temperature in sublethal exposures to nitrite 1. methemoglobin formation in channel catfish exposed at different acclimation temperatures, 2. recovery from methemoglobinemia at different acclimation temperatures, E) the effect of the fish anesthetic TMS-222 on nitrite-induced methemoglobinemia in channel catfish 1. supression of nitrite-induced methemoglobinemia, 2. dose-response curve for TMS-222 induced methemoglobinemia, and F) if a methemoglobin reductase system is present in channel catfish.

Reductions in baroreflex responsiveness have been thought to increase the prevalence of orthostatic hypotension in endurance trained athletes. To test this hypothesis, cardiovascular responses to orthostatic stress, cardiopulmonary and carotid baroreflex responsiveness, and the effect of cardiopulmonary receptor deactivation on carotid baroreflex responses were examined in 24 men categorized by maximal aerobic power (V02max) into one of three groups: high fit (HF, V0-2max=67.0±1.9 ml•kg^-1•min^-1), moderately fit (MF, V0-2max=50.9±1.4 ml•kg^-1•min^-1), and low fit (LF, V0-2max=38.9±1.5 ml•kg^-1•min^-1). Orthostatic stress was induced using lower body negative pressure (LBNP) at -5, -10, -15, -20, -35, and -50 torr. Cardiopulmonary baroreflex responsiveness was assessed as the slope of the relationship between forearm vascular resistance (FVR, strain gauge plethysmography) and central venous pressure (CVP, dependent arm technigue) during LBNP<-35 torr. Carotid baroreflex responsiveness was assessed as the change in heart rate (HR, electrocardiography) or mean arterial pressure (MAP, radial artery catheter) elicited by 600 msec pulses of neck pressure and neck suction (NP/NS) from +40 to -70 torr. Pressures were applied using a lead collar wrapped about the subjects' necks during held expiration. Stimulus response data were fit to a logistic model and the parameters describing the curve were compared using two-factor ANOVA. The reductions CVP, …

The cellular regulation of acidification and intracellular ph (pHi) was studied in the integument of Rana pipiens, a model renal epithelium. Acidification was enhanced by : (1) chronic metabolic acidosis, (2) high salinity adaptation, and (3) ibuprofen treatment.

Low oxygen tolerances of ten fishes were estimated using an original nitrogen cascade design, and reciprocally transformed to express responses as ventilated volume necessary to satisfy minimal oxygen demand (L·mg O2^-1). Values ranged from 0.52 to 5.64 L·mg^-1 and were partitioned into three statistically distinct groups. Eight stream fishes showed moderately high tolerances reflecting metabolic adaptations associated with stream intermittency. Juvenile longear sunfish and two mollies comprised the second group. High tolerance of hypoxia may allow juvenile sunfish to avoid predation, and mollies to survive harsh environmental oxygen regimens. The sheepshead minnow was the most tolerant species of low oxygen, of those examined, explaining its presence in severely hypoxic environments.

Through the use of natural history records, published literature, and personal sampling (2011-2016) a total of 454 caddisfly species represented by 24 families and 93 genera were documented from the south-central United States. Two Hydroptilidae species were collected during the 2011-2016 collection efforts that are new to the region: Hydroptilia scheringi and Mayatrichia tuscaloosa. Eightteen species are endemic and 30 are considered species of concern by either federal or state agencies. The majority of each of these groups is Hydroptilidae, or microcaddisflies. Trichoptera community structure, by minimum number of species, was analysed in conjunction with large-scale geographical factors to determine which factor illustrated caddisfly community structure across the region. Physiographic provinces compared to other geographic factors analyzed best-represented caddisfly communities with a minimum of 10 or more species. Statistically, Hydrologic Unit Code 4 (HUC 4) was the most significant geographical factor but low number of samples representing this variable rendered it less representative of caddisfly community structure for the study area.

During dynamic exercise the arterial baroreflexes have been thought to reset to the prevailing level of systemic pressure in order to modulate transient changes in blood pressure with the same sensitivity (gain) as at rest. To test this hypothesis, cardiovascular responses to dynamic exercise and carotid baroreflex responses to graded neck suction and neck pressure (NS/NP) were examined in seven men of moderate fitness (V02 = 41.4±3.6 ml O2*kg^-1*min^-1) during two levels (20% and 40% of peak oxygen uptake) of steady-state exercise. In addition, deactivation of cardiopulmonary baroreceptors has been thought to increase carotid baroreflex responsiveness in the quiescent state in man.

Six sites within the Denton and Hickory Creek watersheds were sampled over three years to assess the impact of seasonal intermittent stream conditions on the ichthyofauna. An integrated approach using field and laboratory techniques was employed to evaluate the responses of the fishes.