West Nile virus (WNV) is an emerging infectious disease that has widespread implications for public health practitioners across the world. Within a few years of its arrival in the United States the virus had spread across the North American continent. This research focuses on the development of a spatially explicit GIS-based predictive epidemiological model based on suitable environmental factors. We examined eleven commonly mapped environmental factors using both ordinary least squares regression (OLS) and geographically weighted regression (GWR). The GWR model was utilized to ascertain the impact of environmental factors on WNV risk patterns without the confounding effects of spatial non-stationarity that exist between place and health. It identifies the important underlying environmental factors related to suitable mosquito habitat conditions to make meaningful and spatially explicit predictions. Our model represents a multi-criteria decision analysis approach to create disease risk maps under data sparse situations. The best fitting model with an adjusted R2 of 0.71 revealed a strong association between WNV infection risk and a subset of environmental risk factors including road density, stream density, and land surface temperature. This research also postulates that understanding the underlying place characteristics and population composition for the occurrence of WNV infection is important for mitigating future outbreaks. While many spatial and aspatial models have attempted to predict the risk of WNV transmission, efforts to link these factors within a GIS framework are limited. One of the major challenges for such integration is the high dimensionality and large volumes typically associated with such models and data. This research uses a spatially explicit, multivariate geovisualization framework to integrate an environmental model of mosquito habitat with human risk factors derived from socio-economic and demographic variables. Our results show that such an integrated approach facilitates the exploratory analysis of complex data and supports reasoning about the underlying spatial ...
Absence of functional phenylalanine hydroxylase results in phenylketonuria (PKU). Viable treatments remain few, expensive and secondary conditions such as osteopenia occur in most PKU patients. Objective 1: Given the recently described roles of gut microbes to aid host digestion, an orally administered genetically engineered probiotic as the delivery vehicle for enzyme replacement therapy was created. The engineered probiotic, pHENOMMenal, produced phenylalanine ammonia lyase with significant production of trans-cinnamate (phenylalanine cleavage product) in vitro and resulted in a reduction of 515 μM in blood phenylalanine when fed to PKU animals for 14 days (from 2307µM ± 264µM to 1792µM ± 261µM, n = 6, P < 0.05). The control probiotic produced no change in blood phenylalanine. Thus, pHENOMMenal treatment in PKU mice demonstrated engineered microbes could compensate for a metabolic deficiency of the host. Objective 2: Evaluate the PAHenu2 mouse model of PKU for a genetic discrepancy causing ocular enlargement and delayed development observed only after the PAHenu2 mutation was crossed to the C57BL/6J mouse. When compared to healthy littermates, ELISA indicated a consistent but insignificant decrease in plasma IGF-1 and an increase in ocular IGF-1 in PKU animals. SNP screening demonstrated a differential inheritance of IGF-1 alleles in healthy and PKU animals based on PAH allele inheritance. Ocular and developmental phenotypes in the PAHenu2 colony match those described in previous IGF-1 studies. Understanding the IGF-1 inheritance discrepancy will enable better osteopenia research using PAHenu2 mice and allow breeding of a healthier mouse colony for continued research. Collectively the results from this work describe a new therapeutic approach for treatment of PKU as well as a better understanding of the PAHenu2 mouse model to study this disease.
Leguminous plants are able to fix nitrogen by establishing a symbiotic relationship with soil dwelling bacteria, called rhizobia. The model plant Medicago truncatula forms a partnership with Sinorhizobium meliloti whereby the plant gains bioavailable nitrogen and in exchange the bacteria gains carbohydrates. This process occurs within nodules, which are structures produced on the roots of the plants within which nitrogen is fixed. M. truncatula incomplete root elongation (MtIRE) was localized to the infection zone, which is zone II of indeterminate nodules. It was shown to encode a signaling kinase so it was anticipated to play a role in nodulation. Mutants of MtIRE in the R108 background, mutagenized with the Tnt1 retrotransposon, were obtained from reverse screen, and were assessed to determine if a disrupted MtIRE gene was the cause of nitrogen fixation defective nodules. Mutant line NF1320, having a mutant phenotype, showed typical Mendelian segregation of 3:1 when backcrossed to R108. Experimental results show that MtIRE gene is not the cause of the mutant phenotype, but was linked to the causative locus. MtIRE co-segregated with the mutant phenotype 83%. Southern blot and the first version of the M. truncatula genome (version 3.5) reported a single MtIRE gene and this was shown to be on chromosome 5 but the latest version of the M. truncatula genome (version 4.0) showed a second copy of the gene on chromosome 4. The genome sequence is based on the A17 reference genome. Both genes are 99% identical. Genetic markers that originate from flanking sequence tags (FSTs) on both chromosome 4 and 5 were tested in an attempt to find an FST that co-segregated with the mutant phenotype 100%. An FST derived from a Tnt1 insertion in Medtr4g060930 (24F) co-segregated with the mutant phenotype closely, with 76% co-segregation. Medtr4g060930 (24F) is on chromosome 4, making it ...
Legumes are unique plants because they form special structures “nodules”, via symbiotic relationships with rhizobial bacteria present in the soil. Once rhizobia mature inside nodules, they fix atmospheric nitrogen providing a source of bioavailable nitrogen to the plant. To discover novel genetic components involved in the legume-rhizobia symbiosis by using forward genetic screening, we have isolated Medicago truncatula Tnt1 insertion mutants in the R108 ecotype, which are defective in nodule development and symbiotic nitrogen fixation in response to Sinorhizobium meliloti. Out of three mutants NF11044, NF11217 and NF8324, one of the mutants showed brown nodules and Fix- phenotype that is defective in symbiotic nitrogen fixation. The other two mutants showed white nodules and Fix- phenotype, also indicator of defects in symbiotic nitrogen fixation. To identify the underlying mutation causing the phenotype, we have developed molecular genetic markers by obtaining genomic sequences flanking the Tnt1 insertions by TAIL-PCR and Illumina sequencing. To carry out co-segregation analysis, back-crossed BC1F2 segregating populations were obtained. These are being phenotyped, genotyped and analyzed for co-segregation of the phenotype with the Tnt1 genetic markers. Back-crossing also has the effect of reducing the Tnt1 insertions, which are not linked to the nodulation defective phenotypes. Out of the three mutants, NF8324 harbors exactly the same insertion as in the rsd-1 Tnt1 mutant NF11265. The defect in NF11217 is caused by a Tnt1 insertion in the previously described PLC gene; the site of this insertion is close to that found in a different mutant, NF0217. For mutant NF11044, we developed linkage markers that place the defective locus on chromosome 7. To further characterize co-segregation in NF11044, a mapping population has been created by crossing the mutant with other ecotypes: A17 and A20. We tested mutants and wild type plants with linkage marker A20 X NF11044 BC1F2 that segregates 3:1(wild ...
Pseudomonas aeruginosa are medically important bacteria that are notorious for causing nosocomial infections. To gain more knowledge into understanding how this organism operates, it was decided to explore the pyrimidine biosynthetic pathway. Pyrimidine synthesis, being one half of the DNA structure, makes it a very important pathway to the organism’s survivability. With previous studies being done on various genes in the pathway, pyrE has not been studied to the fullest extent. To study the function of pyrE, a site directed mutagenesis was done to completely knock out pyrE, which encodes the protein orotate phosphoribosyl transferase that is responsible for converting orotate into orotate monophosphate (OMP). A mutation in this step leads to accumulation and secretion of orotate into the medium. Analyzing virulence factors produced by the mutant and comparing to the wild type, some intriguing features of the mutant were discovered. One of the findings was the over expression of virulence factors pyoverdin and pyocyanin. Pyocyanin over expression, based on the results of this study, is due to the accumulation of orotate while over production of pyoverdin is due to the accumulation of dihydroorotate. The other virulence factors studied were motility assays, exoproducts, and growth analysis. All virulence factor production was reduced significantly in the mutant compared to the wild type. The casein protease assay showed absolutely no production of proteases in the mutant. The conclusion is that orotate accumulation leads to a significant reduction in virulence factor production in Pseudomonas aeruginosa. In addition to that, it was found that excess orotate in the wild type led to a decrease in quorum sensing regulated products.
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.
A bacteriological study was made of a number of prepared foods that were bought ready-to-eat, for home consumption, from several food establishments in Dallas, Texas. The purpose of this study was to show whether these foods could be a potential source of food poisoning; whether there are any particular foods that should have greater care than others in order to protect their quality; and whether the bacteriological contamination could have been prevented by strict observance of the city regulations for handling foods.
The induction of phenylketonuria in mice through the use of excess dietary phenylalanine is an area in which limited research has been done. This study intends to pursue further work in this area, more specifically, to study the effects of excess dietary phenylalanine and the phenylalanine analogue A.P.B.A. (2-amino-3-phenyl butanoic acid) (7) on brain serotonin and brain norepinephrine. In addition, the effects of these two compounds on the incidence of audiogenic seizures will be explored.
"In order to gain an adequate idea of the sanitary condition of the drinking fountains on the North Texas State Teachers College campus, it was found necessary to approach these bacteriological studies from a seasonal point of view."--1.
The role that aquatic actinomycetes play, in the production of tastes and odors in water supplies has been investigated since 1948. The ability of these organisms to produce by-products in lakes and streams, which renders the water unpalatable, is of considerable public health importance. It is desirable that the waterworks industry has as much information as possible concerning the factors that contribute to the growth of these organisms. Since it appears that the aquatic actinomycetes may be isolated from most fresh-water sources, the problem of diversified environments and nutritional requirements offers an excellent field of investigation. The fresh-waters of the world contain variable quantities of electrolytes that may determine in part the biological activity of these organisms. The unsolved questions in this instance are concerned with the electrolytes present and their quantitative effects on the growth and development of these forms.
The purpose of this study is to gather information related to the characteristics of two groups of undergraduate non-science majors; namely, those students who once considered science as a career and subsequently changed to a non-science major and those who have never considered a career in science. It is frequently observed that children in the elementary school have an intense interest in science. One of the principal concerns of this study is how and for what reasons has the interest in science changed between elementary school and college? It is also the purpose of this study to gather information related to the attitudes of these college students toward the science courses they have had in high school and toward their science teachers. In attempting to arrive at an answer, the group who once considered a science career and those who have never considered an occupational choice in a field of science will be compared in the following areas: 1. General information such as sex, age, size of high school attended, rank within their graduating classes, college classification and military experiences. 2. Occupations and hobbies of parents. 3. Experiences which may influence attitudes toward science such as elementary school science, high school science courses, high school science teachers, attitudes toward science requirements, high school courses liked most, high school courses liked least, and membership in science clubs. 4. College science courses completed. 5. Extent of the interviewees' present interest in science, Finally, the circumstances surrounding the tentative choice of a science career by those who once considered such a career will be discussed.
Biotransformation and biodegradation rate constants were determined for naphthalene, lindane, and phenol in water samples from three different sources. Rate constants produced from monitoring disappearance of the parent chemical (biotransformation) were compared to those obtained from mineralization of the chemical (ultimate biodegradation) by ¹⁴CO₂ evolution as well as acidification of the residual ¹⁴C-labeled compound (primary biodegradation). Rate constants were statistically different for the three chemicals. The water source affected the rate constants. When biomass measurements of the waters were considered and second-order rate constants were derived, there was no statistical evidence that this parameter gave a reliable rate constant statistic that could be useful in predicting the fate of any of naphthalene, lindane, and phenol in these waters.
This study examines ultrastructural changes occurring in seven- and fourteen-day populations of Trypanosorfa lewisi when 60 mg sodium salicylate is administered to the host. These changes were related to the host-immune response. Seven-day trypanosomes showed approximately 10 posterior volutin granules. Seven-day trypanosomes whose host had received salicylate exhibited. 30 to 40 volutin granules, and their posterior tip exhibited volutin granules in high numbers sometimes excluding other cellular elements. Fourteen-day trypanosones showed fewer volutin granules than seven-day, salicylate-treated ones. Salicylate treatment caused no additional ultrastructural alterations. Thus the volutin granules are not linked to the reproduction inhibiting antibody (ablast in) but may be involved in the formation of the trypanocidal antibodies.
The problem with which this investigation was concerned was the comparison of cedar elm populations in different stands along creeks in Denton County, Texas, and the relationship of certain population parameters to various substrates present at stand sites, Parameters investigated eluded average basal area, basal-area density, transect-segment density, intertree distance, lateral distance, frequency, diameter breast-high, diameter breast-high size-class distribution, and immature-tree density. Variations among populations of Ulmus crassifolia Nutt were noted and analyzed in terms of soil particle size and existing community conditions.
A new rapid computer assisted micro-titer plate interferon assay system was developed and characterized for use in high capacity clinical and research applications. The biological aspect of the assay was a modification of the assay methods of Finter, Armstrong and McManus. It was an application of spectrophotometric quantification of the reduction of viral cytopathic effect (CPE) as reflected by neutral red dye uptake by viable cells. A computer program was developed for the extrapolation of raw data to reference interferon units.
Bluegill were exposed to 3 and 30 pg/L lindane and 20 and 200 pg/L naphthalene to determine uptake rate constants, K1 depuration rate constants, K2, and bioconcentration factors, BCF. Correlations were determined between lipid normalized and non-lipid normalized BCFs, and between observed Kl, K2 and BCFs and predicted values. The K1 values for both chemicals and concentrations were similar. The K2 values were different (1.04 day~1, 0.46 day 1). Naphthalene was more rapid. BCFs for lindane (315) and naphthalene (98) were different. Lipid normalized BCFs for naphthalene were more variable than non-lipid normalized BCFs. The reverse was observed for lindane BCFs. Predicted K1, K2 , and BCFs were in agreement with observed values.
Aryl hydrocarbon hydroxylase (AHH) was induced 15-fold in Ambystoma tigrinum by intraperitoneal injection of 3-methylcholanthrene in corn oil, or 10-fold by addition of aromatic polycyclic hydrocarbons to the aqueous environment of the neotene animal. The cytochrome P-450-associated microsomal enzyme is similar to the inducible, one-gene, autosomal-dominant system typical in the laboratory mouse and man. Differences in optimal temperature for enzyme induction and activity were noted in organ culture of human and Ambystoma tissues, and ratios of benzpyrene metabolites differed between Ambystoma and Mus. The half life of enzyme activity induced in vivo was related to the excretion of hydrocarbon metabolites.
Production rates of seven species of fish, along with food-web interactions, were determined for one year in a pond. Production of fish in the pond amounted to 208.9 q/m2/yr. Over 95% of the production occurred in the summer, with Y of Y fish contributing 83.8%. There were two food-web interactions observed in Y of Y fishes: crappie vs. bass and bullhead vs. sunfish. When Y of Y fish shifted to benthic diets in the spring, the small biomass of benthos available could not sustain the larger biomass of fish. Competition for the available food resulted in decreased production rates for the fish community.
The Problem of the cause and control of tastes and odors in water supplies has been the subject of a great many investigations during the last half-century; however, many questions in this field remain to be answered. Theories relating to the cause of tastes and odors occurring in water are still rather numerous and, at present, only a few of them are compatible. Although several procedures have been employed for the eradication of tastes and odors from water supplies, none of them are completely successful.
Rates of primary production and community metabolism were monitored over a one year period using the diurnal oxygen method. Certain physico-chemical parameters were also measured, and autotrophic standing crops were estimated. An in-depth study was made of the phytoplankton community and various diversity indicies were calculated. Simple correlations were run between all parameters measured (biotic and abiotic), and their inter-relationships examined. Multiple linear regression analyses were used to develop equations predictive of production and community metabolism. Bluegreen algae were the dominant phytoplankters with blooms occurring in late summer and fall. Yearly mean production was approximately 21 kcal per meter square per day with a mean photosynthetic efficiency of 1.2 per cent. Of the various parameters measured turbidity and water temperature were most important in determining rates of primary production.
The life history and ecology of Neochoroterpes mexicanus was studied from data collected September, 1971, to August, 1972, and January to December, 1973, in the Brazos River, Texas. Nymphal development, instar analysis, voltinism, standing crops, and production estimates were determined from the quantitative samples taken in 1971 and 1972. Aspects of the life history and food habits of 230 specimens were arrived at from qualitative samples and light box captures in 1973. Laboratory investigation in 1973 helped in establishing instar analysis, egg incubation and description, and first instar descriptions. Neochoroterpes mexicanus appeared to have three generations per year with brood overlap in the summer and fall. It displayed 16 and 19 instars for overwintering and combined summer generations respectively.
"The orientation of this study began with a collection of the grasses of Erath County during their flowering periods. Collections were made in the Spring and Fall of 1950 and 1951 to obtain both vernal and autumnal grasses. Identifications were made from the grass floras previously mentioned and checked against specimens in the herbarium of North Texas State College for verification. In addition, the list was checked by W.A. Turney, Conservationist, United States Department of Agriculture of Dublin, Texas. Finally, the list was compared with that prepared by W.M. Cory for the plant areas of which Erath County is a part. On the basis of the above identifications, a critical study of the vegetative characteristics was made and a key based on these features prepared. The width of the blad and characteristics of the ligule, roots, culms, and sheaths were used to distinguish each of the eighty-six specimens found in the collection area. A drawing was made of the longitudinal section of the juncture of the blade and the sheath of each grass. This diagnostic section includes the collar, ligule, a part of the blade and sheath, and auricles, if present."-- leaf 5.
"The area of study was restricted to those common flowering herbs of Denton County, Texas, which have conspicuous flowers or a conspicuous flower cluster. There were, however, many plants included in this flora which are common to several counties of north-central Texas. Since there has been no previous key devised for the herbs of Denton County, Texas, the purpose of this key was to provide a flora which could be used by elementary and high school instructors, as well as any other interested persons who lack an extensive knowledge of botanical nomenclature." -- leaf iv.
Cultured human lymphocytes may be assayed for aryl hydrocarbon hydroxylase (AHH) in whole cell preparations. The optimum assay conditions are pH 8.5, and 1.5 mM Mg++. The reaction is linear with time and cell number, and is inhibited by CO. Estradiol may inhibit induction of AHH by 3-methylcholanthrene, but is a poor competitor for the enzyme. A Caucasian population was assayed for AHH activity. The distribution was lognormal; no difference was found in cultured cells from males and females or smokers and nonsmokers. Cells from relatives of lung cancer patients showed higher activity. An American Indian population showed no difference from the Caucasian population in enzyme level. No linkage was found between AHH and 16a-hydroxylase.
In view of the discrepancies and conflicts produced by previous studies on amphibian lymph hearts, a study was initiated to reinvestigate the pharmacological, temperature, and electrical aspects of lymph heart physiology. Bullfrogs were chosen as the experimental animal, All lymph heart responses to experimentation were physiographically recorded as myograms and electrograms. The results are in agreement with previous studies on some aspects and in conflict on others. From the results obtained, lymph heart muscle appears to possess both skeletal and cardiac muscle properties as evidenced by drug responses and reactions to temperature. The precise components of the electrogram remain unclear. It is suggested that further investigation should be made to better determine the true nature of lymph hearts.
This investigation studies effects of environmental factors on growth and carotenogenesis in Corynebacterium strain 7ElC. Changes in pH were found to effect growth more than carotenogenesis. However, certain nutrients or long incubation periods stimulated carotenoid formation more than growth. Dark conditions in a mineral salts-glucose medium stimulated growth, but minimized carotenogenesis. Tryptic soy broth or yeast extract elicited carotenogenesis in darkness. Although brief light exposure during inoculation was photoinductive, continuous exposure to light following inoculation was required for maximum pigment synthesis. Dark grown stationary phase cells required 24-hours of light for maximum pigment synthesis. Chloramphenicol inhibition of carotenogenesis in dark grown cells exposed to light showed that enzymes needed for carotenoid synthesis were absent from dark grown cultures.
The myocardium is known to release CPK, LDH1 , and GOT in response to ischemia as a result of myocardial infarction. This study was designed to induce the release of cardiac enzymes without adversely effecting the myocardium by perfusion hypothermia, thereby suggesting that these enzymes are not as specific in the diagnosis of myocardial infarction as once thought. Hypothermia was by in vivo perfusion of the left anterior descending coronary artery. Enzyme activity was measured from sera samples spectrophotometrically and electrophoretically. Significant CPK and LDH1 increases were observed in animals perfused between 25 and 19 C. These results indicate that, while heart function remained unchanged, an alteration occurred in the membrane integrity of the myocardial cells.
Aryl hydrocarbon hydroxylase activity was studied in cultured human lymphocytes using 3-methylcholanthrene, 1,2- benzanthracene, and 4'-bromoflavone as inducers. The substrates used to run the 60 minute assay were benzo(α)pyrene and diphenyloxazole. At the optimum bromoflavone concentration for induction of aryl hydrocarbon hydroxylase, the induced enzymatic activity compared favorably with that of aryl hydrocarbon hydroxylase induced by 3MC in a 96 hour lymphocyte culture using BP as the assay substrate. The whole cell human lymphocyte system was found to have as much or more activity in 20 ml vials using Joklik's-Modified Minimum Essential Medium at a pH optimum of 7.5 with no co-factor added as did the Roswell Park assay system. The whole cell assay showed that levels of aryl hydrocarbonhydroxylase inducibility in lumphocytes from smokers and non-smokers varied without regard to the subjects' smoking habits. The assay system also indicated that intact lymphocytes generate a similar group of benzo(α)pyrene metabolites as that produced by a hepatic microsomal preparation from C57B1/6J mice.
This study used polyacrylamide gel electrophoresis to study the acid-phenol soluble proteins of five strains (A. vinelandii 12837, A. vinelandii 0, A. chroococcum 8004, A. macrocytogenes 8702, A. tumefaciens) of bacteria grown on Burk's nitrogen-free media, Trypticase Soy Broth, and 0.3% butanol medium. The results showed that the protein patterns can be used for the identification and possibly the taxonomic classification of the Azotobacter. The change of phenotype of the bacteria in different media followed the change of protein quantity and quality. There was no absolute similarity between any two of the species studied and this suggests a genetically heterogenous group of organisms while the amount of common proteins suggests close genetic relationships. Further studies are necessary to confirm the status of A. tumefaciens.
"As a means of defining the purpose of the problem, the following objectives were considered: (1) to list the species of birds observed in Denton and neighboring counties; (2) to assign a descriptive status to each species; (3) to estimate the relative abundance of each species (4) to annotate the list with data from other sources, when additional data provide a more accurate and complete description of the status of the species in Denton County; (5) to designate the section of the county in which each species was most frequently observed; and (6) to briefly summarize the changes in bird populations during the period 1950-1956, and to suggest some hypotheses which help explain these changes." -- leaf 6.
A method is presented for 160hydroxylase (SAH) induction in cultured human lymphocytes. SAH, a microsomal-associated enzyme, effects the oxidative conversion of 17pestradiol to estriol, which competes for cytoplasmic binding sites. 17,-estradiol and estrone are known mammary carcinogens, while estriol and its epimers have been suggested to have anticarcinogenic properties. To substantiate genetic variations of hydroxylase activity, an analysis of estrogen-induced cultured human lymphocytes was conducted to evaluate the frequency distribution of low, intermediate, and high SAH activity. Frequency analysis indicated that the control population distribution of SAH activity does not corroborate a proposed trimodal expansion of human SAH activity. A log normal distribution of SAH activity does exist, which suggests a polygenic mode of genetic control. SAH activity in a population of breast cancer patients and relatives of breast cancer patients showed no statistical difference from the SAH activity in the control population.
The Amistad Reservoir in southern Val Verde County, Texas will impound a considerable amount of surface water in a semi-arid region in which natural surface water is scarce. Construction of the dam began in 1963 and the reservoir began to fill in the summer of 1968. This large impoundment could have a considerable ecological impact on the area. The purpose of this research was to study the ecological distribution and zoogeographic affinities of the herpetofauna and to establish an ecological baseline against which any future changes could be measured.
Chick embryo fibroblasts and rat kidney cells infected in vitro with Rous Sarcoma viruses were treated with 3-deazaguanine (3-DG). The findings revealed that 3-DG inhibited virus-induced cellular transformation. Degree of inhibition is dependent on concentration and frequency of media change. 3-DG at the concentrations tested will not reverse transformed cells to the untransformed state and does not have marked effect on replication of viruses. Upon removal of 3-DG, its effect was shown to be reversible. Cell growth was generally retarded in medium containing 3-DG. When xanthosine and inosine were added to the medium, cell growth was unaffected, but it increased in guanosine.
During four growing seasons, aquatic vascular plant production and distribution were studied in Pat Mayse Lake, Texas, a 2425 hectare oligo-mesotrophic reservoir. The dominant macrophyte population was Myriophyllum spicatum L. Growth rates and regrowth rates of mechanically harvested Myriophyllum beds were found to be dissimilar. Based on estimates of watermilfoil nutrient content, there were insufficient nutrients in the entire population to alter the trophic status of this reservoir should all of the nutrients be instantaneously released. Sediments were the primary nutrient (nitrogen and phosphorus) sink. Bank erosion and solids transport from the watershed appear to contribute most of the sediments and a lake-wide mean sedimentation rate of 2.5 cm/year was estimated from sediment trap and core sample data.
Evidence is presented to support the conclusions that (1) North Lake reservoir is less productive, contains lower standing crops of phytoplankton and total organic carbon than other local reservoirs; (2) that neither the phytoplankton nor their instantaneously-determined primary productivity was detrimentally affected by the power plant entrainment and (3) that the effect of the power plant is to cause nutrient limitation of the phytoplankton primary productivity by long-term, subtle, thermally-linked nutrient precipitation activities.
Carotenoid pigments were extracted from Corynebacteriuma poinsettiae (wild type) ATCC 9682, and from 108 mutants obtained by exposure of a streptomycin resistant strain of C. poinsettiae to ultra-violet light irradiation and N-methyl- N'-nitro-N-nitrosoguanidine. The pigments were characterized by their absorption maxima, Rf-values, and partition ratios in petroleum ether and methanol. Thin layer chromatography was used to compare pigments of the wild type with those of the mutants. Possible biosynthetic pathways in carotenoid synthesis of the wild type were postulated on the basis of the observed genetic blocks. Mutants were found which suggested the existence of a linear pathway in carotenoid synthesis from the aliphatic C4 0 molecule to the bi-cyclic C50-diol. Other mutants suggested possible alternative pathways in the biosynthesis of these pigments or the presence of intermediates not detectable by thin layer chromatography.
In a minimal medium supplemented with glucose and yeast extract, the optimum pH for the growth of C. poinsettias was found to be 7.5. The organism requires thiamine, biotin, and pantothenic acid for growth. No absolute requirement was found for any amino acid, purine or pyrimidine although an amino acid mixture was stimulatory. Casamino acids could be substituted for the synthetic amino acid mixture. Yeast extract provided an additional factor(s) necessary for maximal growth. The results suggest that the unknown factor found in yeast extract might be purified by a combination of solvent extraction, and adsorption and elution from charcoal.
The purpose of this study was to focus attention on the physiology of the bdellovibrio-host interaction and to determine the metabolic requirements for this reaction. Since bdellovibrio is an aerobic organism, direct measurements of respiration, turbidity, and viable cell counts are reliable indications of the metabolic activity of the cells. It was determined that the metabolic requirements for the parasitic interaction are constituents from either metabolically active host cells or cells which are capable of at least some metabolic activity. The nutritional requirements of host-independent bdellovibrios suspended in buffer are not met by the presence or absence of viable or nonviable Enterobacter aegnes. Unlike the HD bdellovibrios, the HI bdellovibrios lack the ability to make economical use of their self-digesting processes.
Investigations have shown that the hypothalamus and pituitary respond to decreases in body temperature by stimulating thyroid release of T_3 and T_4 . This study was designed to bypass the control of the hypothalamus and pituitary gland and investigate the direct effect of temperature on the thyroid gland. Hypothermia was by an in vivo isolated perfusion of the thyroid gland. Radio-immunoassay was used to measure T_3 and T_4 concentrations. Significant increases were observed in animals perfused between 36º and 25ºc. These results indicate that the thyroid gland is directly effected by decreased temperature and that it is capable of exerting control over body temperature independent of the hypothalamus and pituitary gland. Lower perfusion temperatures produced no significant increases.
A rabbit keratoconjunctivities model was used to evaluate ophthalmic formulations containing 1 percent sodium cephalothin in silicon oil, a 1 percent sodium cephalothin aqueous solution, and a 0.3 percent gentamicin sulfate solution. Rabit eyes were inoculated intracorneally with Pseudomonas aeruginosa, Staphylococcus aureus, or Streptococcus pneumoniae, After topical treatment, none of the antibiotic formulations were effective in the P. aeruginosa model; all three showed good activity against S. aureus, and against S. pneumoniae, the caphalothin formulations were more effective than gentamicin.In a related stability study, the cephalothin potency of the silicon formulation was maintained for 16 weeks at 4, 25, and 450 C These studies suggest that sodium cephalothin can be formulated as an effective and stable ophthalmic dosage form.
The effects of external electric fields (EEF) on brain activity in anesthetized rats were studied. The field strengths used, 9 kV/m and 5 kV/m, both D.C. and A.C. (60Hz) were in the range of those measured beneath current overhead transmission lines. Brain activity was monitored from surface electrodes and from electrodes stereotaxically implanted in the posterior-lateral portion of the hypothalamus. It was found that 9 kV/m and 5 kV/m EEF's both D.C. and A.C. brought about statistically significant changes in hypothalamic activity, however, the effects were bi-directional, (i.e. increases and decreases). Only seven of the 60 animals exposed showed changes in the EEG recorded with surface electrodes. The data clearly indicate that (1) anesthetized animals do respond to a change in the external electric field around them, (2) the hypothalamus may contain special electro-receptors that, in turn, may alter various other physiological processes, and (3) the data indicates the need for further research to help government agencies to establish more adequate safety guidelines.
Mean salinity concentrations in the four reservoirs (Moss, Ray Hubbard, Texoma and Possum Kingdom) ranged from 0.2 ppt in Moss Lake to 2.01 ppt in Possum Kingdom Lake. Reservoir sodium and chloride concentrations were hypotonic to hypertonic to plasma levels in all species. Interspecific differences were seen in ionic concentrations within each reservoir. Total osmotic and sodium concentrations in carp, Cyprinus carpio, were correlated to their concentrations in the reservoirs. No such relationship was noted for chloride, potassium and calcium. A laboratory study indicated that fish collection by electroshock did not bias plasma ion concentrations. Exposures to wide variations in ionic concentrations did not appear to induce stress in the species studied.
The basis of this investigation is to characterize growth property differences in normal versus virally transformed cells. Using a temperature-sensitive mutant of Rous sarcoma virus, the cells' transformation state is regulated by the growth temperature; at 33°C the cells are transformed, while at 39°C the cells have normal characteristics. The morphology of NRK cells is elongated and fibroblastic; when transformed the cells are rounded. Normal cells grow to a monolayer and stop, while transformed cells grow to saturation densities greater than just a monolayer amount. Transformed cells can form foci when grown in mixture with normal cells. Normal cells must be in contact with the culture vessel in order to grow, but transformed cells lack anchorage dependence for growth.
Seven species of planktonic microcrustacea were identified from the North Texas State University Golf Course Pond. Total adult microcrustacean community density, biomass and biocontent, and seasonal cycles of each species were compared with northern populations. Species diversity and evenness indices were highest in summer and lowest in spring. Variations in microcrustacean density showed a positive correlation with density of phytoplankton. Temperature had a direct effect on metabolic rates of two species of copepods. Metabolic rates of pond species were lower at common temperatures than those of northern populations. An estimate of annual energy flow through the pond ecosystem showed cladocerans contributed the greater percentage of total energy to the next trophic level.
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.
Olfactory transduction mechanisms are best studied when specific blocking agents are available with which to modify cellular responses to odorant stimulation. This study is an electrophysiological investigation of functional group-specific olfactory acceptor mechanisms using ethylbromo acetate (EtBrAc), a World War I war gas which inhibits olfactory responses to odorant stimulation. The major findings of this investigation show that (1) vaporous EtBrAc is found to be a quick and effective inhibitor of electroolfactogram (EOG) responses to odorant stimulation, (2) isoamyl acetate is shown to protect EOG responses to a wide variety of odorants, inclusive of itself, from the inhibition effect of EtBrAc treatment, and (3) amine acceptor sites exist which are resistant to the inhibitory effects fo EtBrAc treatment.
A new procedure has been developed to concentrate the phosphofructokinase from muscle of Ascaris suum with minimum loss of activity. By utilizing this method, 50 ml fraction was concentrated to a final volume of 3 ml in about 1.5 h without loss in enzyme activity. The concentrated enzyme had a specific activity of 64 units per mg. Ascaris muscle-cuticle was incubated in 50 1M solutions of either acetylcholine, serotonin, y-aminobutyric acid, levamisole, or saline alone. Phosphate analysis of the isolated phosphofructokinase from each incubation revealed that the enzyme contained the following moles of phosphate per subunit: 2.9 (acetylcholine), 2.2 (serotonin), 2.0 (y-aminobutyric acid), 1.5 (levamisole), and 3.4 (salne alone). The present study did not establish a direct correlation between degree of phosphorylation and phosphofructokinase activity. Phosphofructokinase from muscle of Ascaris suum appears to contain several phosphorylation sites, and one of these sites is required to be phosphorylated in order for the enzyme to exhibit maximum activity under physiological conditions.
2,5-Diphenyloxazole (PPO) was tested as a potential alternate inducer for the aryl hydrocarbon hydroxylase (AHH) system. Its apparent lack. of carcinogenicity and toxicity provide a possible system for investigation of enzyme systems related to chemical carcinogenesis without exposure of the researcher to potent carcinogenic compounds. These studies found PPO to be an inducer of AHH in cultured human lymphocytes. When PPO was utilized as a substrate for the AHH assay system, the major metabolites produced were strongly fluorescent. A simple fluorometric assay was developed which employed PPO as the substrate and which measured constitutive activity more efficiently than similar assays using benzo(a)pyrene as the substrate. Quantitation of both basal and induced lymphocyte AHH metabolism of PPO may be applicable to human population studies and may provide a tool to determine possible genetic variables with respect to carcinogen metabolism related to cancer risk.
Responses of periphyton and phytoplankton productivity in the lower Sulphur River (Texas-Arkansas) to bleach-kraft mill effluent (BKME) were monitored using in situ ¹⁴C incubation. Carbon assimilation rates measured downstream of mill discharge were substantially reduced from upstream levels. Periphyton and phytoplankton chlorophyll a concentrations remained relatively unchanged by the presence of BKME. Periphyton ash-free dry weight increased near the mill outfall, but decreased further downstream. Calculated productivity efficiencies (productivity:biomass) varied with variations in ¹⁴C rates. A laboratory bioassay was designed to determine the effect of BKME light-attenuation on photosynthetic rates of upstream Sulphur River periphyton and Selenastrum capricornutum Prinz. Pooled results of bioassay runs indicated a 20 per cent BKME concentration effectively reduced control ¹⁴C-assimilation levels by 50 per cent. The downstream reduction observed for in situ productivity was 5 per cent lower than that predicted by the color bioassay.
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