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Articles 571 - 600 of 686

Full-Text Articles in Biology

Development Of A Semi-Synthetic Medium Supporting Adherent Growth In Coagulase-Negative Staphylococci, Abbas Sadeghi Aug 1992

Development Of A Semi-Synthetic Medium Supporting Adherent Growth In Coagulase-Negative Staphylococci, Abbas Sadeghi

Dissertations and Theses

A semi-synthetic medium for use in determining adherent growth with Staphylococcus epidermidis and Staphylococcus saprophyticus was developed. Production of an adherent biofilm was dependent upon the presence of hematin in the growth medium. Clinical strains of Staphylococcus epidermidis were tested for production of an adherent biofilm in trypticase soy broth, the semi-synthetic medium and the hyperalimentary nutrient solution used in the neonatal hospital unit. An adherent biofilm was obtained when Staphylococcus epidermidis was cultured m hematin supplemented hyperalimentary solution. Growth in the hyperalimentary nutrient solution diluted with fetal calf serum showed the same growth rate as when the nutrient solution …


Brainstem Auditory Evoked Potentials In Anuran Amphibians, Marc Brandon Carey May 1992

Brainstem Auditory Evoked Potentials In Anuran Amphibians, Marc Brandon Carey

Dissertations and Theses

In this study, I looked at the effects of sound level, temperature and dehydration/hypernatremia on the brainstem auditory evoked potential (BAEP) of four species of anuran amphibians (Rana pipiens, Rana catesbeiana, Bufo americanus and Bufo terrestris). The BAEP was used because it allowed me to monitor both the peripheral and central aspects of auditory nervous function simultaneously and over a long period of time.


Three Dimensional Mammalian Skull Morphology, Suzanne Louise Krippaehne Mar 1992

Three Dimensional Mammalian Skull Morphology, Suzanne Louise Krippaehne

Dissertations and Theses

This thesis deals with archiving morphological data utilizing a three dimensional coordinate system. Morphological reference points are archived via rectangular position coordinates, rectangular position vectors, and spherical position vectors. The concepts of translation trajectories, translation vectors, and relative position vectors are developed. Analysis of three dimensional coordinate data utilizing translation trajectories and translation vectors is described. In order to test the methodology developed, the method is applied to an analysis of harbor porpoise, Phocoena phocoena L., skull morphology. (Key words: morphology, ontogenetic trajectories, allometry, position coordinates, position vectors, translation trajectories, translation vectors, relative position vectors, and harbor porpoise).


The Morphology, Physiology, And Fine Structure Of A Toluene-Oxidizing Strain Of Pseudomonas Putida, Barry Clayton Anderson Jan 1992

The Morphology, Physiology, And Fine Structure Of A Toluene-Oxidizing Strain Of Pseudomonas Putida, Barry Clayton Anderson

Dissertations and Theses

The role of microorganisms in the degradation of xenobiotics in the environment is well established. Bacteria from the genus Pseudomonas are particularly well adapted to the degradation of hydrocarbons, aromatics, and numerous other natural and introduced substrates. We have isolated a strain of Pseudomonas putida, designated PC2P15, that uses toluene, phenol, benzene, and a number of other substrates as its sole sources of carbon and energy.


Effects Of Conalbumin Bound Iron On The Growth Of Salmonella Paratyphi B And Salmonella Thompson, John Nicholas Mason Dec 1991

Effects Of Conalbumin Bound Iron On The Growth Of Salmonella Paratyphi B And Salmonella Thompson, John Nicholas Mason

Dissertations and Theses

I have investigated the possibility that specific conalbumin (ovotransferrin) iron saturation levels enable less virulent strains of Salmonella to become more virulent. Iron starved cells of two pathogenic Salmonella strains, S. paratyphi B var. java and S. thompson, were cultured in iron limited media at 3 different iron conalbumin saturation levels. Results indicate that strains differ significantly at both low and high iron saturation conalbumin. These differences depict a growth advantage for S. paratyphi B which correlates with reports by the Centers for Disease Control that S. paratyphi B was 3 times more frequent in blood isolates than S. …


The Physiology And Molecular Biology Of Iron Nutrition For Cyanobacteria, Nancy Walters Unsworth Aug 1991

The Physiology And Molecular Biology Of Iron Nutrition For Cyanobacteria, Nancy Walters Unsworth

Dissertations and Theses

In addition to nitrogen and phosphorus, iron is an essential nutrient for oceanic primary productivity. Unlike nitrogen and phosphorus however, negligible amounts of iron are supplied to surface waters through recycling or mixing but instead from the limited and sporadic input of aeolian particulate. The low concentration of iron that becomes biologically available from the dust places a serious constraint on the heavily iron-dependent processes of photosynthesis and nitrate reduction which affect primary productivity. As much as 47% of the total oceanic primary productivity can be attributed to cyanobacteria making them critical organisms in the biogeochemical cycles. This thesis addresses …


An Analysis Of The Ph Tolerance And Substrate Preference Of Isolated Skeletal Muscle Mitochondria From Bufo Marinus And Rana Catesbeiana, Jeffrey Mark Duerr May 1991

An Analysis Of The Ph Tolerance And Substrate Preference Of Isolated Skeletal Muscle Mitochondria From Bufo Marinus And Rana Catesbeiana, Jeffrey Mark Duerr

Dissertations and Theses

The concept of maximal oxygen consumption (VO2 max) implies that there is a limit to the amount of oxygen that can be consumed by an organism in a given time. Many attempts have been made to delineate exactly what factor or factors are limiting to VO2 max. Current models focus on the steps over which oxygen must traverse in order to get from the ambient air to the mitochondria. However, no model has addressed the issue of whether or not carbon dioxide flux may impose a limit to VO2 max. Impedance of carbon dioxide flux may have …


Macroinvertebrate Drift Abundance Below Bonneville Dam And Its Relation To Juvenile Salmonid Food Habits, William Douglas Muir Nov 1990

Macroinvertebrate Drift Abundance Below Bonneville Dam And Its Relation To Juvenile Salmonid Food Habits, William Douglas Muir

Dissertations and Theses

There is a paucity of information concerning the invertebrate food resources available to juvenile salmonids in the Columbia River as they migrate seaward. Construction of mainstream dams has altered the temperature cycle, flow regime, and substrate which indigenous invertebrates were adapted to. Studies on how the macroinvertebrate community has adapted to these alterations have been neglected. This study was undertaken to help fill this void.

Macroinvertebrate drift samples were collected over a three year period in the Columbia River downstream from Bonneville Dam. Samples were collected with a D-ring plankton net fished on the bottom for one-half hour. Two sites …


Biogeography And Species Density Distributions Of Tasmanian Mammals, Jerry E. Bevers Aug 1990

Biogeography And Species Density Distributions Of Tasmanian Mammals, Jerry E. Bevers

Dissertations and Theses

Separated from mainland Australia by the Bass Strait, Tasmania has acted as an island preserve maintaining large populations of many mammalian species presently uncommon, rare, or extinct on mainland Australia.

There are few studies of Tasmanian mammal distributions. Recent distributional maps, based on information from surveys and mammal specimens, allowed for an investigation of the species density distributions of the terrestrial mammals of Tasmania. Compilation of species' distributional information into species density distributions provides an overview as to which areas may provide the most significant habitat for the greatest number of species; what geographic variations may influence species distributions; and …


The Electrokaryotype And Molecular Characterization Of Trypanosoma Cervi Isolates Using Recombinant Dna Techniques, J. Lindsley Bennett Jul 1990

The Electrokaryotype And Molecular Characterization Of Trypanosoma Cervi Isolates Using Recombinant Dna Techniques, J. Lindsley Bennett

Dissertations and Theses

The distribution of trypanosomes infecting wild ruminants of North America has only recently been investigated. Many isolates have been mensurally studied and were determined to be conspecific with Trypanosoma cervi. Widely divergent forms exist however, between host species and seasonally within a host. To determine the validity of all inclusions in the taxon and the extent of intraspecific variability, trypanosome isolates of moose, reindeer, antelope, muledeer, Roosevelt Elk and two discrete transplant populations of Rocky Mountain elk were characterized and differentiated using recombinant DNA techniques.


The Effect Of Plant Growth Regulators On The Growth Of Closterium Moniliferum, Cynthia Lehua Warnock Christensen Mar 1990

The Effect Of Plant Growth Regulators On The Growth Of Closterium Moniliferum, Cynthia Lehua Warnock Christensen

Dissertations and Theses

Physiologic responses to Gibberellic Acid (GA), 1-Naphthalene Acetic Acid (NAA), Benzylaminopurine (BAP), and Abscisic Acid (ABA), suggest that Closterium moniliferum has the ability to utilize these plant growth factors. The growth promoters NAA and GA both increased growth when added to the media. The cell division regulator BAP (a synthetic cytokinin). also had a promotive effect on growth. Abscisic acid was found to be inhibitive to growth.


Hplc Analysis Of Myoglobin Tryptic Peptides From Selected Species Of Cetaceans, David Lawrence Hayteas Feb 1990

Hplc Analysis Of Myoglobin Tryptic Peptides From Selected Species Of Cetaceans, David Lawrence Hayteas

Dissertations and Theses

Due to the large gaps in the fossil record, the evolutionary history of the mammalian order Cetacea is incomplete and controversial. Increasingly researchers are utilizing molecular and biochemical procedures to supplement cetacean paleontology. One of these methods is the comparison of amino acid sequences of myoglobin among species of this order. since this method is time-consuming and expensive, an alternative procedure is desirable.

As a candidate for such an alternative, peptide mapping was performed on selected species of cetaceans. This mapping was done utilizing High Performance Liquid Chromatography (HPLC). Myoglobin was extracted from skeletal muscle, purified, digested with trypsin, the …


Dna Fingerprinting Analysis Of Captive Asian Elephants, Elephas Maximas, Laura Louise Bischof Jan 1990

Dna Fingerprinting Analysis Of Captive Asian Elephants, Elephas Maximas, Laura Louise Bischof

Dissertations and Theses

This thesis examined the effectiveness of DNA fingerprinting analysis for paternity ascertainment and the establishment of relatedness of captive Asian elephants (Elephas maximas). Eighteen Asian elephants from three North American zoos were examined. Thirteen of these elephants were wild caught. Relationships between these elephants and the remaining elephants born in captivity were known.


Methionine Metabolism In Fasciola Hepatica, Carol Theresa Ayer Jan 1990

Methionine Metabolism In Fasciola Hepatica, Carol Theresa Ayer

Dissertations and Theses

5'-Deoxy-5'-methylthioadenosine (MTA) is derived from s-adenosylmethionine (AdoMet) during the synthesis of the polyamines spermidine and spermine. Methionine can be regenerated from MTA by one of two mechanisms. In mammalian cells and some microorganisms, MTA is degraded to adenine and 5-methylthioribose-1-phosphate (MTR-1-P) via MTA phosphorylase. In certain other microbes, however, MTA is catabolized in two steps; first to adenine and 5-methylthioribose (MTR) via MTA nucleosidase followed by conversion of MTR to MTR-1-P via MTR kinase.

This study was to demonstrate the presence of MTA nucleosidase or MTA phosphorylase in both redia containing cercariae and adult Fasciola hepatica Linnaeus, 1758. If MTA …


Temporal Patterns Of Nectar And Pollen Production In Aralia Hispida: Implications For Reproductive Success, James D. Thomas, Mary A. Mckenna, Mitchell B. Cruzan Aug 1989

Temporal Patterns Of Nectar And Pollen Production In Aralia Hispida: Implications For Reproductive Success, James D. Thomas, Mary A. Mckenna, Mitchell B. Cruzan

Biology Faculty Publications and Presentations

Large plants of Aralia hispida present their pollen and nectar in hundreds of small flowers than open sequentially over 2—3 wk in a pattern of synchronized protandry that alternates male and female phases. The primary pollinators, bumble bees, are able to discover individual plants with elevated levels of either nectar or pollen, and to return to them more often than to less rewarding plants. Both pollen and nectar are presented gradually over time in such a way as to favor traplining behavior by the bees, with many, frequent visits. In controlled environments, lifetime sugar production per flower varies among plants, …


Analysis Of Mitochondrial Dna Restriction Fragment Patterns In Killer Whales, Orcinus Orca, Tracy Alison Stevens Apr 1989

Analysis Of Mitochondrial Dna Restriction Fragment Patterns In Killer Whales, Orcinus Orca, Tracy Alison Stevens

Dissertations and Theses

The mitochondrial DNA restriction fragment patterns of killer whales (Orcinus orca) were investigated in order to determine the level of genetic differentiation that exists between killer whales from various geographic locations. Twenty one killer whales were examined, seventeen of which were captive killer whales that originated from the North Atlantic and Northeast Pacific Oceans. Two were captive-born animals and two were killer whales that stranded along the Northeast Pacific coast.

DNA was extracted from blood and/or tissue samples, cleaved with a variety of restriction endonucleases and the DNA fragments were separated by horizontal agarose gel electrophoresis. The DNA …


Nitrogen And Iron Interactions In Filamentous Cyanobacteria, David Allen Hutchins Jan 1989

Nitrogen And Iron Interactions In Filamentous Cyanobacteria, David Allen Hutchins

Dissertations and Theses

The investigations described in this paper are an attempt to further define and quantify the interrelationship of nitrogen fixation and iron nutritional physiology in these two species. Chapter II will present and compare data on nutritional ratios of field collected Trichodesmium colonies and laboratory Anabaena cultures, with the intent of examining possible correlations between observed iron levels and protein nitrogen and chlorophyll concentrations, as well as nitrogen fixation rates. Chapter Ill is an examination of nitrogen fixation and siderophore production in Anabaena with emphasis on the possible implications of hypothesized synergistic effects of these two physiological capabilities on cyanobacterial dominance …


Seasonal Trailing Behavior And Corticosterone Levels In Male Red-Sided Garter Snakes (Thamnophis Sirtalis Parietalis), Pamela Kay Thinesen Jan 1989

Seasonal Trailing Behavior And Corticosterone Levels In Male Red-Sided Garter Snakes (Thamnophis Sirtalis Parietalis), Pamela Kay Thinesen

Dissertations and Theses

Mechanisms of how red-sided garter snakes (Thamnophis sirtalis parietalis) travel up to 18 km from summer feeding sites to hibernation dens are not understood. In this study, monthly and seasonal trailing behavior were investigated to determine whether red-sided garter snakes prefer to follow trails of snakes from the same den (den-mates) versus trails made by other conspecifics (non-den-mates). Snakes from five different hibernacula in Manitoba, Canada, were involved in the study. Eighteen were adults and 15 were subadults. Subadult red-sided garter snakes do not return to hibernacula until their second year of life, so their trailing behavior was of interest …


Intestinal Granules Found In The Parasitic Nematodes Ancylostoma Caninum, And Oesophagostomum Radiatum, Alan Joseph Gianotti Sep 1988

Intestinal Granules Found In The Parasitic Nematodes Ancylostoma Caninum, And Oesophagostomum Radiatum, Alan Joseph Gianotti

Dissertations and Theses

The parasitic nematodes Ancylostoma caninum and Oesophagostomum radiatum were collected and analyzed for intestinal inorganic granules. Three means of identification were utilized to determine the composition granules, including birefringence, x-ray diffraction and energy dispersive spectrometric (EDS) analysis. Initial x-ray diffraction results of the two worms showed a calcium sulfide presence within the worms. Closer examination of the granules within Ancylostoma caninum however, utilizing EDS analysis revealed their composition to be zinc sulfide. These results concur with those of Rogers (1940) and Clark (1956) who found zinc sulfide granules in several species of Strongylus. The ZnS granules seem to be …


The Distribution Of Zooplankton In Selected Oregon Lakes, Mary Elizabeth Claska Aug 1988

The Distribution Of Zooplankton In Selected Oregon Lakes, Mary Elizabeth Claska

Dissertations and Theses

Zooplankton samples were collected from 166 Oregon lakes. The lakes included a wide range in size, trophic status, and water quality. Lakes were located throughout the state. Zooplankton were identified using standard taxonomic keys and counted. Seventy-four species were identified from the 200 total samples, including 32 species of cladocera, 22 copepods, and 11 rotifers. Two species of copepod were recorded for the first time in Oregon: Diaptomus mississippiensis and Diaptomus pallidus. Seven species had widespread distributions throughout most of the watersheds in the state. Seventeen other species had distributions restricted to eastern, central, or western Oregon. The remaining …


Determination Of Homology Between The Arsenic Resistance Plasmids R45 And R773 In Escherichia Coli, Joshua T. Clark May 1988

Determination Of Homology Between The Arsenic Resistance Plasmids R45 And R773 In Escherichia Coli, Joshua T. Clark

Dissertations and Theses

The resistance transfer factor R45 from Escherichia coli confers inducible arsenate and arsenite resistance in that bacterium. The genes for these resistances were cloned into the EcoR1 - Sph1 multiple cloning site of PGEM3 Blue vector (Promega) to produce a 4.9 kilobase plasmid, pJC1. This recombinant plasmid, pJC1, conferred IPTG induced resistance to arsenite and arsenate. In addition, pJCl was tested for homology with the E. coli plasmid R773, which encodes for arsenic resistance in that bacterium as well.

Through DNA-DNA hybridization the arsenic resistance determinants of R45 and R773 were compared. Under stringent hybridization conditions, R45 demonstrated DNA sequence …


Febrile Response And Activity In The Crayfish, Pacifasticus Leniusculus Trowbridgii, Kenneth A. Fletcher Feb 1988

Febrile Response And Activity In The Crayfish, Pacifasticus Leniusculus Trowbridgii, Kenneth A. Fletcher

Dissertations and Theses

Poikilothermic and endothermic animals demonstrate febrile response to infection with bacteria or to injection with endogenous pyrogen extract of Prostaglandin E1. Febrile response is measured in endotherms as a relative change in metabolically achieved body temperature and in poikilotherms as an increase in selected temperatures relative to previously established preferred temperatures. Final preferendum change with environmental factors or associated physiological states.

Crayfish Pacifasticus leniusculus trowbridgii were injected with 0.2 ml suspension of alcohol-killed gram-negative Aeromonas hydrophila bacteria in 0.9% saline. Injections were into the coxopodite of the cheliped. The crayfish were monitored in an aquatic thermal gradient by …


The Effect Of Cold Acclimation On The Temperature Preference Of The Goldfish, Carassius Auratus, And The Brown Bullhead, Ictalurus Nebulosus, Alfred Lord Nov 1987

The Effect Of Cold Acclimation On The Temperature Preference Of The Goldfish, Carassius Auratus, And The Brown Bullhead, Ictalurus Nebulosus, Alfred Lord

Dissertations and Theses

Two species of fish, Carassius auratus and Ictalurus nebulosus, were subjected to cold acclimation regimes. Acclimation temperatures were slowly lowered to 3°C, then held for a period of time. At various times during this regime, fish were taken out and allowed to spend time in a temperature gradient to determine their preferred temperatures. Carassius were left in the gradient just long enough to determine a measure of the acute temperature preference, while Ictalurus were left in the temperature gradient for longer periods of time to observe any changes that might occur as the fish adjusted to selected temperatures. In …


The Impact Of Weather On Kingbird Foraging Behavior, Michael T. Murphy Nov 1987

The Impact Of Weather On Kingbird Foraging Behavior, Michael T. Murphy

Biology Faculty Publications and Presentations

Foraging data on Eastern Kingbirds (Tyrannus tyrannus) were collected during the early breeding season in eastern Kansas to test the hypothesis that foraging rate and other aspects of foraging behavior vary with weather. Foraging characteristics of five additional kingbird species were also examined to assess Fitzpatrick's (1980) generalization that kingbirds (Tyrannus spp.) are aerial hawking specialists. In Eastern Kingbirds, total foraging rate was independent of air temperature, cloud cover, wind speed, and time of day, but the rate of aerial hawking varied directly with air temperature and inversely with cloud cover (both P < 0.05). Effects of the two variables were additive. The percentage of foraging movements that were aerial hawks also increased with temperature and declined with cloud cover, and, hover-gleaning and perch-to-ground sallying were observed mainly during cloudy weather. Sally (i.e., foraging flight) distance correlated directly with perch height and air temperature, and large insects were captured almost exclusively in long upward or horizontal flights. I interpret these data to indicate that foraging behavior and the capture of large, flying insects depends on weather because of how it affects the activity of insect prey. Foraging data on kingbirds support Fitzpatrick's generalization, but the relative use of aerial hawking varies considerably among species. Resident Tropical Kingbirds( T. melancholicus) are the most specialized foragers, whereas the migrant and widely distributed Eastern Kingbird appears to be the most generalized. Certain habitats also appear to favor the use of particular foraging methods (e.g., outward striking in grasslands and perch-to-ground sallying in drier, open habitats).


Decrease In Selected Temperature After Intracranial Dopamine Injections In Goldfish, Hercules Theodore Panayiotides-Djaferis Aug 1987

Decrease In Selected Temperature After Intracranial Dopamine Injections In Goldfish, Hercules Theodore Panayiotides-Djaferis

Dissertations and Theses

Goldfish (Carassius auratus) (40-80g) were injected with dopamine into the forebrain to study the possible involvement of this amine in central temperature regulation in these fish. Dopamine caused a decrease in selected temperature after injection into the rostral nucleus preopticus periventricularis (NPP). This effect was dependent on the dose of dopamine administered. Doses of 25, 50, 100 and 250 ng were used, injected in a volume of 0.2μ1. Injections in regions adjacent to the NPP elicited hypothermic effects only at the higher dosages. These effects were not consistent. Injections in caudal regions of the NPP elicited no effect. …


The Effect Of Body Temperature On Arteriovenous Oxygen Difference During Rest And Activity In The Toad, Bufo Marinus, Wayne Bryant Palioca Jul 1987

The Effect Of Body Temperature On Arteriovenous Oxygen Difference During Rest And Activity In The Toad, Bufo Marinus, Wayne Bryant Palioca

Dissertations and Theses

The relative contribution of arteriovenous oxygen (A-V O2) difference to thermally-induced and activity-induced changes in metabolic rate (VO2) were delineated in the toad, B. marinus. In conjunction, the influence of rest and activity, temperature, and removal of the pericardial sac on separation efficiency (Es) in the anuran ventricle was determined by direct measurement of arterial and venous percent oxygen saturation (% saturation), using a microsampling technique.


The Role Of Iron Nutrition In Regulating Patterns Of Photosynthesis And Nitrogen Metabolism In The Green Alga Scenedesmus Quadricauda, Dennis Raymond Ades Jan 1987

The Role Of Iron Nutrition In Regulating Patterns Of Photosynthesis And Nitrogen Metabolism In The Green Alga Scenedesmus Quadricauda, Dennis Raymond Ades

Dissertations and Theses

The influence of iron nutrition on patterns of photosynthetic behavior, nitrogen metabolism, and fixed-carbon allocation is reported for a common freshwater green alga. Cultures of Scenedesmus quadricauda were grown in Fraquil medium in which iron concentrations ranged from 1.0 μM to 0.01 μM (log 10-6 to 10-8 M, respectively). Carbon 14 and nitrogen uptake experiments were conducted at photosynthetically saturating and subsaturating photon flux densities.


Norepinephrine And Temperature Regulation In Goldfish, Lonnie Paul Wollmuth Jan 1987

Norepinephrine And Temperature Regulation In Goldfish, Lonnie Paul Wollmuth

Dissertations and Theses

Cannulae were implanted into forebrain loci of goldfish (Carassius auratus; 45-90 g) to determine (i) the effects and site of action of intracranial norepinephrine (NE) injections on behavioral thermoregulation and (ii) the mechanism and the types of adrenoreceptors involved in the thermoregulatory effect of NE. After 30 min in a thermal gradient, implanted fish were injected with norepinephrinebitartrate salt (2.5-500 ng NE) in a total volume of 0.2 ul (carrier was 0.7% NaCl). Injections of 5, 10, 25, and 50 ng NE into the anterior aspect of the nucleus preopticus periventricularis (NPP1 Peter and Gill 1975) led to consistent, dose-dependent …


Body Size, Nest Predation, And Reproductive Patterns In Brown Thrashers And Other Mimids, Michael T. Murphy, Robert C. Fleischer Nov 1986

Body Size, Nest Predation, And Reproductive Patterns In Brown Thrashers And Other Mimids, Michael T. Murphy, Robert C. Fleischer

Biology Faculty Publications and Presentations

We describe the breeding biology of Brown Thrashers (Toxostoma rufum) in Kansas, and combine this with data from other temperate-zone breeding Mimidae to characterize reproductive patterns in this group. Brown Thrashers produced clutches of 3 to 6 eggs, but clutches of 4 predominated. Most pairs raised 2 broods per year. Incubation required between 13 and 14 days, and hatching was usually asynchronous. Though sample size was small, asynchrony appeared to increase in frequency towards the end of the breeding season. Nestlings grew rapidly, and in 10 days or less most pre-fledgingg rowthw as completed. Young fledgedn ormallya t 11 days …


Hemodynamics During Pregnancy: A Model For Cardiac Enlargement, David James Mendelson Jul 1986

Hemodynamics During Pregnancy: A Model For Cardiac Enlargement, David James Mendelson

Dissertations and Theses

Cardiac output increases by 30-50% during mammalian pregnancy. This increase is reflected by elevation in both heart rate and stroke volume. The primary mechanism of increased stroke volume appears to be cardiac enlargement, rather than increased preload, afterload, or contractility. Animal studies have shown that enlargement of the heart occurs prior to an increase in uterine blood flow during pregnancy and this type of enlargement can be mimicked by sex steroid administration.

Systemic vascular resistance greatly decreases during pregnancy and with sex steroid administration. It has been postulated that systemic vascular resistance may be a signal for heart size changes. …