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Articles 241 - 270 of 270

Full-Text Articles in Biochemistry, Biophysics, and Structural Biology

Role Of Centriolar Matrix And Striated Rootlets In Centriolar Pairing And Orientation During Spermatogenesis In Hydractina Echinata, Maurice G. Kleve Jan 1985

Role Of Centriolar Matrix And Striated Rootlets In Centriolar Pairing And Orientation During Spermatogenesis In Hydractina Echinata, Maurice G. Kleve

Journal of the Arkansas Academy of Science

Transmission electron microscopy of the spermatogenic stages of the hydroid, Hydractinia echinata, reveals a series of complex structural and positional changes in the centrioles of spermatocytes and spermatids. The newly generated centriolar pairs of spermatocytes form an unusual four-centriole aggregate that persists until cell division. The distal centrioles of this aggregate are shrouded with a very dense matrix that accumulates after centriolar replication. This matrix facilitates the mechanical attachment between distal centrioles and microtubular nucleating satellites, striated rootlets and pericentriolar processes. The association of these accessory structures occurs sequentially and is repeated in spermatocytes and spermatids. An electron dense plaque, …


A Study Of The Action Of Bovine Cathepsin D On Intramuscular Connective Tissue, Elimosaria Elikalia Maeda May 1983

A Study Of The Action Of Bovine Cathepsin D On Intramuscular Connective Tissue, Elimosaria Elikalia Maeda

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Cathepsin D has been postulated to play a role in the tenderization of meat with ageing. Meat toughness has been related to connective tissue content and degree of myofibrillar shortening. This investigation was undertaken to determine the activity of cathepsin D on bovine intramuscular connective tissue.

Highly purified cathepsin D preparations from bovine spleen and bovine sternomandibularis muscle were obtained by ammonium sulfate fractionation followed by affinity chromatography on pepstatin coupled to controlled pore size alkyl amine glass beads. Maximum proteolytic activity using hemoglobin as substrate was obtained at pH 3.5 and 3.8 for bovine spleen and muscle cathepsin D, …


Historical Patterns Of Phytoplankton Productivity In Lake Mead, Richard T. Prentki, Larry J. Paulson Jan 1983

Historical Patterns Of Phytoplankton Productivity In Lake Mead, Richard T. Prentki, Larry J. Paulson

Publications (WR)

Lake Mead was impounded in 1935 by the construction of Hoover Dam. The Colorado River was unregulated prior to then and therefore was subjected to extreme variations in flows and suspended sediment loads. Hoover Dam stabilized flows and reduced suspended sediment loads downstream, but Lake Mead still received silt-laden inflows from the upper Colorado River Basin. The Colorado River contributed 97% of the suspended sediment inputs to Lake Mead, and up to 140 x 1O6 metric tons (t) entered the reservoir in years of high runoff. Most of the sediments were deposited in the river channel and formed an …


Assay, Purification, And Characterization Of A Pantetheine Hydrolyzing Enzyme From Pig Kidney, Carl Thomas Wittwer May 1982

Assay, Purification, And Characterization Of A Pantetheine Hydrolyzing Enzyme From Pig Kidney, Carl Thomas Wittwer

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A microsomal glycoprotein hydrolyzing pantetheine to pantothenate and cysteamine has been solubilized and purified to homogeneity as determined by sodium dodecylsulfate electrophoresis. Four rapid, independent assays of pantetheine hydrolysis are described and compared along with a method for localizing enzymatic activity on polyacrylamide gels. The enzyme is solubilized on exposure to butanol and purified by heat treatment, (NH4)2SO4 fractionation, hydrophobic chromatography, and hydroxyapatite chromatography. The glycoprotein, purified 5600-fold in 22% yield, has a specific activity of 14 μmoles pantothenate produced/min/mg of protein, 35 times that previously reported. The enzyme has a pH optimum of 9.0-9.5 and a …


Food Habits Of Largemouth Bass, Micropterus Salmoides (Lacepede) And Spotted Bass, Micropterus Punctulatus (Rafinesque), From Beech Fork Reservoir, A New Impoundment In Wayne And Cabell Counties, West Virginia, Michael A. Arcuri Jan 1981

Food Habits Of Largemouth Bass, Micropterus Salmoides (Lacepede) And Spotted Bass, Micropterus Punctulatus (Rafinesque), From Beech Fork Reservoir, A New Impoundment In Wayne And Cabell Counties, West Virginia, Michael A. Arcuri

Theses, Dissertations and Capstones

A study was undertaken to determine the food habits of two game fishes, the largemouth bass Micropterus salmoides (Lacepede) and the spotted bass M. punctulatus (Rafinesque) in Beech Fork Reservoir shortly after its impoundment. A total of 171 largemouth bass and 95 spotted bass were collected from July 1978, through June 1979, and their stomach contents analyzed.

Largemouth bass fed primarily on fishes, particularly young-of-the-year bluegill. Aquatic and terrestrial invertebrates were also important food items, especially during the spring and fall . The dominant aquatic forms were chironomid larvae and pupae while the dominant terrestrial forms were adult dipterans.

Spotted …


Aspects Of Larval Ecology Of Squilla Empusa (Crustacea, Stomatopoda) In Chesapeake Bay, Steven G. Morgan Jan 1980

Aspects Of Larval Ecology Of Squilla Empusa (Crustacea, Stomatopoda) In Chesapeake Bay, Steven G. Morgan

OES Faculty Publications

Larvae of Squilla empusa were collected from the plankton and were laboratory-reared in 16 combinations of temperature and salinity to determine their tolerances. Larvae survived longer and molted more frequently when reared at 25%, and 20° or 25° C, which corresponds to the natural conditions of Chesapeake Bay when the larvae were collected.

A 2 year planktonic survey conducted in the lower region of the bay by the Virginia Institute of Marine Sciences was compared with a survey made at the bay mouth in 1976. The seasonal occurrence of Squilla empusa larvae extended from the last week of July until …


Potential Use Of Hydroelectric Facilities For Manipulating The Fertility Of Lake Mead, Larry J. Paulson, John R. Baker, James E. Deacon Jan 1979

Potential Use Of Hydroelectric Facilities For Manipulating The Fertility Of Lake Mead, Larry J. Paulson, John R. Baker, James E. Deacon

Publications (WR)

Analysis of historical nutrient data for Lake Mead indicates that the fertility of the reservoir has decreased which may be the cause for a corresponding decline in the largemouth bass population. However, it appears that fertility can be manipulated by altering the operation of the dam. The depletion of nutrients in the euphotic zone by phytoplankton and subsequent accumulation in the hypolimnion during summer and fall provide a natural nutrient gradient from which water of varying fertility can be drawn for discharge. This combined with alterations in the depth or seasonal pattern of discharge can possibly be used to enhance …


Pulling The Wool Off, Department Of Agriculture, Western Australia Jan 1979

Pulling The Wool Off, Department Of Agriculture, Western Australia

Journal of the Department of Agriculture, Western Australia, Series 4

The Department of Agriculture has begun a three year project to study the potential for "chemical shearing" or, more correctly, biological defleecing.


Adaptive Mechanisms For Aquatic Existence In Freshwater Turtles, Oscar Gloor Jan 1977

Adaptive Mechanisms For Aquatic Existence In Freshwater Turtles, Oscar Gloor

Honors Theses

Naturalists have often marveled at the ability of some air-breathing vertebrates to remain underwater for long periods of time (that is, "long" from man's reckoning). Seals, penguins, porpoises, and whales are all noted fro their ability to use oxygen stored in various ways to permit them to "stay under" for many minutes.

The return of vertebrates, which evolved on land, to an aquatic existence has been a much discussed subject from an evolutionary standpoint. That there are many advantages to life underwater is easily seen simply by the fact that, according to fossil records, terrestrial life arose from the sea. …


Effect Of Altitude On The Peripheral Degradation Of Thyroxine In The Uinta Ground Squirrel (Citellus Armatus), Stuart K. Ware Dec 1976

Effect Of Altitude On The Peripheral Degradation Of Thyroxine In The Uinta Ground Squirrel (Citellus Armatus), Stuart K. Ware

Theses and Dissertations

Various methods were employed to detect changes in the peripheral degradation of thyroxine (T4) in adult Uinta ground squirrels (Citellus armatus) collected at two different altitudes (5400 and 9000 feet.) Plasma half-life of injected T4-125I (tl/2) was significantly decreased with altitude, as was T4-125I distribution space (TDS) and T4 degradation and secretion rate (TSR). In vitro deiodination of T4-125I by heart homogenates was not affected, while urinary excretion of thyroxine derived iodide was increased at high altitude 44-70 hours post-injection. Both total and free serum T4 concentrations were reduced at high altitude, although not significantly. The cause of the reduced …


Physiological Adaptations Of Aquatic Turtles, Oscar Gloor Dec 1975

Physiological Adaptations Of Aquatic Turtles, Oscar Gloor

Honors Theses

Naturalists have long noted the remarkable ability of aquatic turtles to remain submerged for long periods of time. Only recently, though, has much serious attention been given to discovering the mechanisms which enable turtles to survive for so long in the relatively hypoxic aquatic environment.


The Effect Of Altitude On Thyroid Function Of The Uinta Ground Squirrel (Citellus Armatus), Wendell Lee Wells Aug 1975

The Effect Of Altitude On Thyroid Function Of The Uinta Ground Squirrel (Citellus Armatus), Wendell Lee Wells

Theses and Dissertations

Thyroid uptake and distribution of 125I, concentrations of T4 and T3 in serum and thyroids and concentrations of TSH in serum and pituitaries were measured to determine thyroid function of Uinta Ground Squirrels (Citellus armatus) native to 5,400 and 9,000 feet elevations to evaluate alterations in the state of the thyroid due to increased altitude. Uptake of 125I was 60 percent lower by squirrels from 9,000 feet. Incorporation of 125I into T3 was greater at the higher elevation, but absolute thyroid T3 concentrations were similar at both elevations. No significant differences were found in serum T3 concentrations, but squirrels living …


Eutamias Minimus And E. Amoenus: Morphological Cluster Analysis, Sandra Elaine Anderson Aug 1974

Eutamias Minimus And E. Amoenus: Morphological Cluster Analysis, Sandra Elaine Anderson

Dissertations and Theses

Cluster analysis of a large body of data on 180 Oregon specimens of Eutamias minimus and E. amoenus suggest that overall length of skull, basal length of skull and length of palate are taxonomically critical. If their sum is less than 71.3 millimeters the animal is E. minimus. If the sum is greater than 72.7 millimeters the animal is E. amoenus. If the sum is between 71.3 and 72.7 millimeters, other factors must be considered before the animal can be identified. Of the 180 specimens, there were 60 E. minimus, 114 E. amoenus, 2 hybrids, 2 …


Absorption Of Caffeine Through Isolated Rat Small Intestine, William James Hatch Aug 1974

Absorption Of Caffeine Through Isolated Rat Small Intestine, William James Hatch

Theses and Dissertations

Intestines of fifty-six albino rats of the Holtzman strain were removed and perfused with Krebs bicarbonate buffered solutions containing caffeine. After one hour of absorbtion, caffeine was extracted from the serosal fluids in chloroform and concentrations were determined spectrophotometrically. It was found that all portions of the small intestine transported caffeine against a concentration gradient. This transport mechanism demonstrated saturation kinetics and was inhibited by ouabain. It was concluded that the movement of caffeine from the mucosa to the serosa of the small intestine cannot be the result of simple diffusion. Possible mechanisms by which the absorption of caffeine takes …


The Effects Of Thiamin Deficiency And Thiamin Antagonists On Cardiac Function In The Rat, D. James B. Sutherland Apr 1973

The Effects Of Thiamin Deficiency And Thiamin Antagonists On Cardiac Function In The Rat, D. James B. Sutherland

Theses and Dissertations

A study was made to determine what biochemical changes were involved in the slowing of the rat heart rate during thiamin deprivation, pyrithiamin or oxythiamin treatment. The appearance of bradycardia during progressive thiamin deficiency was shown to be related to the reduction in myocardial enzymatic activity of pyruvate (PDH) and 2-ketoglutarate (2-KGDH) dehydrogenase, and not due to inanition alone since pair-fed control rats did not show bradycardia until the agonal stage. Bradycardia was not the result of reduced energy since CP, ATP, ADP, and AMP levels remained normal even though PDH and 2-KGDH activity dropped to 20% of normal by …


Autoradiographic Studies Of The Distribution Of Serotonin In The Rat Brain, Brent D. Wagstaff Aug 1971

Autoradiographic Studies Of The Distribution Of Serotonin In The Rat Brain, Brent D. Wagstaff

Theses and Dissertations

Serotonin (5-hydroxytryptamine, 5-HT), considered to be a synaptic transmitter within the central nervous system, has been shown to be localized mainly in the paleocortex of the brain. Others have shown disturbances of normal 5-HT metabolism to be associated with mental illness and disease. Attempts to inject tritium labelled 5-HT into cerebrospinal fluid of the rat brain for anatomical localization studies were·made. The following observations were noted, (1) there exists a perivascular space in which fluid flows and distribution is relatively uninhibited as compared to subarachnoid space, (2) the labelled 5-HT penetration of brain tissue parenchyma is restricted and radioactivity is …


Effect Of Exercise On Tissue Concentrations Of Thyroid Hormones And On Thyroxine Degradation Rate In The Rat, William W. Winder Aug 1971

Effect Of Exercise On Tissue Concentrations Of Thyroid Hormones And On Thyroxine Degradation Rate In The Rat, William W. Winder

Theses and Dissertations

Several methods were used to detect changes in thyroid activity and in degradation of thyroxine (T4) in exercising and sedentary control rats. Rats were run in a motor-driven exercise wheel over a three-week period at progressively increasing work loads and then were run 1.5-2 hours per day for 10-14 days before sacrifice. Disappearance of injected T4-125I from plasma was considerably enhanced by exercise. As determined by isotopic equilibration and paper chromatographic methods, T4 concentration was depressed in plasma and elevated in liver of exercised rats. No significant changes in T4 concentration were observed in heart, kidney, or gastrocnemius muscle. Thyroidal …


A Conceptual Draft Of A Dynamic Hydro-Biological Model For Lake Mead, L. G. Everett, Bureau Of Reclamation Apr 1971

A Conceptual Draft Of A Dynamic Hydro-Biological Model For Lake Mead, L. G. Everett, Bureau Of Reclamation

Publications (WR)

Food and energy transformation in an aquatic system must be understood in order to develop a simulation approach. This report provides a comprehensive study of an aquatic ecosystem. The objectives of this report are to show:

(1) the biological relationships in an aquatic system

(2) the role of nutrients in the biological cycle

(3) the role of abiotic factors in a limnetic environment

(4) the status of the art of "Eutrophication modeling".


Lactic Dehydrogenase Isozyme Isolation By Disc Electrophoresis In Eight Species Of Fringillid Birds, Michael Edwin Darling Jan 1971

Lactic Dehydrogenase Isozyme Isolation By Disc Electrophoresis In Eight Species Of Fringillid Birds, Michael Edwin Darling

Dissertations and Theses

Disc electrophoresis of tissue homogenates from eight species of fringillid birds showed five forms of lactic dehydrogenase. The relative amounts of isozymes were characteristic for each species. This paper classifies some members of the families Fringillidae and Carduelidae in terms of lactic dehydrogenase isozymes and compares the results to other methods of classification.


Urea Or Grain Supplements For Stubble?, H E. Fels Jan 1970

Urea Or Grain Supplements For Stubble?, H E. Fels

Journal of the Department of Agriculture, Western Australia, Series 4

Three methods of supplementing sheep grazing stubble were compared at Merredin Research Station in 1970. The stubble used in the experiment was left after harvesting a nine-bushel crop of Gamenya wheat which was a weed-free second crop on new land. The land had never been sown to legumes.


Urea Block Supplements For Stubble, H E. Fels, R. J. Parkin Jan 1970

Urea Block Supplements For Stubble, H E. Fels, R. J. Parkin

Journal of the Department of Agriculture, Western Australia, Series 4

THERE was a great deal of controversy throughout the summer of Western Australia's 1969-70 drought over the feeding of supplements other than grain to grazing sheep.

This report summarises some of the experiments carried out by this Department to investigate various artificial means of supplementing sheep grazing stubbles and dry summer pastures.

Further details of the experiments can be obtained by contacting the authors.

The results failed to demonstrate economic responses to urea supplements for grazing sheep.


Urea Mixture Formulations, H E. Fels Jan 1970

Urea Mixture Formulations, H E. Fels

Journal of the Department of Agriculture, Western Australia, Series 4

This experiment was done once the experiment above (Urea or Grain Supplements for Stubble) had shown definite but uneconomic responses to a particular mixture of urea, molasses and minerals. The aim was to find whether the response depended on the content of various portions of the mixture, and whether the response to the "shotgun" lick could be explained by the presence of salt, sulphate or cobalt.


Experiments With Urea On Private Farms, R J. Parkin, G. Palmer, A. Haagensen, L. D. White, R. J. Suiter, H. E. Fels Jan 1970

Experiments With Urea On Private Farms, R J. Parkin, G. Palmer, A. Haagensen, L. D. White, R. J. Suiter, H. E. Fels

Journal of the Department of Agriculture, Western Australia, Series 4

Many District Advisers have carried out trials on private farms to test the response to a variety of types of supplementary feeds. This report gives brief details of five such experiments carried out with urea supplements over the last five years. Table 1 summarises the details and results of these trials.


Electrophoretic Patterns Of Plasma Proteins And Hemoglobin Of The Pigeon Columba Liva Domestica, Lloyd D. Snow, Earl L. Hanebrink, Bob D. Johnson Jan 1969

Electrophoretic Patterns Of Plasma Proteins And Hemoglobin Of The Pigeon Columba Liva Domestica, Lloyd D. Snow, Earl L. Hanebrink, Bob D. Johnson

Journal of the Arkansas Academy of Science

No abstract provided.


Metabolic Changes Induced In Rats By Feeding Different Levels Of Galactose With Two Levels Of Corn Oil, Carolyn Qualls Sharp Jan 1967

Metabolic Changes Induced In Rats By Feeding Different Levels Of Galactose With Two Levels Of Corn Oil, Carolyn Qualls Sharp

Journal of the Arkansas Academy of Science

No abstract provided.


Septic Manure Ponds At Lower Kalgan, R Sprivulis Jan 1967

Septic Manure Ponds At Lower Kalgan, R Sprivulis

Journal of the Department of Agriculture, Western Australia, Series 4

BETTER pastures, increasing herd sizes and better quality cows are all contributing to increased production of skim milk and an expansion in pig and calf raising in the dairying areas.


Interrelationships Of Certain Metabolic Responses To Threonine Deficiency And To Various Dietary Carbohydrates In The White Rat, Elizabeth Bright Jan 1965

Interrelationships Of Certain Metabolic Responses To Threonine Deficiency And To Various Dietary Carbohydrates In The White Rat, Elizabeth Bright

Journal of the Arkansas Academy of Science

No abstract provided.


Effect Of Dietary Galactose Vs. Glucose With Corn Oil And With Hydrogenated Coconut Oil On Various Metabolic Functions In Rats, Mabel R. Coleman, Catherine Carroll Jan 1965

Effect Of Dietary Galactose Vs. Glucose With Corn Oil And With Hydrogenated Coconut Oil On Various Metabolic Functions In Rats, Mabel R. Coleman, Catherine Carroll

Journal of the Arkansas Academy of Science

No abstract provided.


Preliminary Report: Monolayer Behavior Studies, 1959, Bureau Of Reclamation Jan 1960

Preliminary Report: Monolayer Behavior Studies, 1959, Bureau Of Reclamation

Publications (WR)

During the fall of 1959, monolayer behavior studies were made on two lakes in the southwest; Boulder Basin of Lake Mead, Nevada, and Lake Sahuaro near Phoenix, Arizona.

These studies were made to evaluate the effect of geographical and climatological conditions on movement and behavior of monolayers. The Lake Sahuaro tests also were used to provide data for design and development of improved methods of application and maintenance of a film on this lake in anticipation of full scale, evaporation-reduction tests to be performed there during the summer of I960.

The Lake Mead studies produced the following general points of …


Studies On Nutritional Muscular Dystrophy. I. Dietary Factors, Ii. Fibrosis And Lipomatosis Of Tissues, Violet Myrtle Wilder May 1938

Studies On Nutritional Muscular Dystrophy. I. Dietary Factors, Ii. Fibrosis And Lipomatosis Of Tissues, Violet Myrtle Wilder

Department of Biochemistry: Dissertations, Theses, and Student Research

Dissertation published as three peer-reviewed papers:

Sergius Morgulis, Violet M. Wilder, and S. H. Eppstein. (September 1938). Further studies on dietary factors associated with nutritional muscular dystrophy. Journal of Nutrition 16(3): 219-227.

Howard C. Spencer, Sergius Morgulis, and Violet M. Wilder. (August 1937). A micromethod for the determination of gelatin and a study of the collagen content of muscles from normal and dystrophic rabbits. Journal of Biological Chemistry 120(1): 257-266.

Sergius Morgulis, Violet M. Wilder, Howard C. Spencer, and S. H. Eppstein. (August 1938). Studies on the lipid content of normal and dystrophic rabbits. Journal of Biological Chemistry 124(3): 755-766.