Light Spectra Distributions in Temperate Conifer-Forest Canopy Gaps, Oregon and in Tropical Cloud-Forest Canopy, Venezuela (open access)

Light Spectra Distributions in Temperate Conifer-Forest Canopy Gaps, Oregon and in Tropical Cloud-Forest Canopy, Venezuela

Light spectra distributions were measured in two different montane forests: temperate and tropical. Spectral light measurements were made in different sized canopy gaps in the conifer forest at H. J. Andrews Experimental Forest in Oregon, USA. Researchers at Oregon State University created these gaps of 20 m, 30 m, and 50 m in diameter. In the tropical cloud forest, spectral light measurements were made in two plots that were permanently established at La Mucuy Parque Nacional in Venezuela, in collaboration with researchers at Universidad de Los Andes. In both studies, spectra and distributions of physiologically active light were analyzed: red, far-red, R/FR ratio, and blue light.
Date: December 1997
Creator: Monteleone, Susan Elaine
System: The UNT Digital Library
Taxonomic Analysis of Marine Actinomycetic Isolates (open access)

Taxonomic Analysis of Marine Actinomycetic Isolates

Though this current study was initiated independently and was not a test laboratory for the taxonomic sub-committee's evaluative program, the problem outlined in this treatise was also designed in an effort to test certain characteristics of the actinomycetes of both a biochemical and morphological nature. This problem employed methods that might absolve or establish certain criteria for taxonomic use in the group of actinomycetes.
Date: August 1959
Creator: Haesly, Doran John
System: The UNT Digital Library
Respiratory Responses in the Freshwater Snail (Pomacea Bridgesii) are Differently Affected by Temperature, Body Mass,and Oxygen Availability (open access)

Respiratory Responses in the Freshwater Snail (Pomacea Bridgesii) are Differently Affected by Temperature, Body Mass,and Oxygen Availability

Pomacea bridgesii is a snail species native to tropical and sub-tropical regions, where it usually faces variability in water, temperature and oxygen level. This study of the effect of temperature on mass-specific oxygen consumption (ṀO2) and its relation to body weight shows that the ṀO2 of juvenile snails in normoxia (18-21 kPa) acclimated at temperature of 25°C ranged from 5 to 58 µMol O2/g/h, with a mean of 41.4 ± 18.3 µMol O2/g/h (n=7). Adult snails in normoxia at 25°C show less variation, ranging from 13 to 23 µMol O2/g/h , with a mean of 24.4± 6.1 µMol O2/g/h (n=12). The Q10 value for juvenile snails was higher in the interval 25-30°C (Q 10=5.74) than in the interval 20-25°C (Q10= 0.286). In adult snails, Q10 was higher in the interval 20-25°C (Q10=3.19). ṀO2 of P. bridgesii in relation to body weight showed a negative linear correlation between metabolic rate and body weight with b values between 0.23 and 0.76. Also, both juvenile and adult snails exhibited weak O2 regulation. In general, the different respiratory characteristics between juvenile and adult snails might be related to the differences of individual life history, which caused them to perform differently in face of temperatures …
Date: August 2016
Creator: Frifer, Wenasa Salem
System: The UNT Digital Library
Search for Surrogate Marker(s) of Immunity Following Vaccination with Experimental Vaccine (Autoclaved Leishmania Major + Bacille Calmette-Guérin) in Human Volunteers (open access)

Search for Surrogate Marker(s) of Immunity Following Vaccination with Experimental Vaccine (Autoclaved Leishmania Major + Bacille Calmette-Guérin) in Human Volunteers

Cutaneous leishmaniasis (CL) is usually a self-limiting lesion on the skin while visceral leishmaniasis is a progressive, systemic disease with high mortality even if treated. The problem associated with treatment and vector control justifies a search for an effective vaccine which seems to be the only practical means to control the disease. The aim of this study is to identify immunological surrogate marker(s) associated with protection against Leishmania infection. The results indicate that a single dose of ALM+BCG induced Thl-like response but the level of such response is not sufficient for full protection. Accordingly, further evaluation of the vaccine is necessary other strategies multiple injections or changing the adjutant.
Date: December 1998
Creator: Mahmoodi, Majid
System: The UNT Digital Library
Nesting Ecology of the Dickcissel (Spiza americana) on a Tallgrass Prairie Relict in North Central Texas (open access)

Nesting Ecology of the Dickcissel (Spiza americana) on a Tallgrass Prairie Relict in North Central Texas

Eighty-three species of vascular plants were inventoried on the prairie relict during peak dickcissel nesting. Based on foliar cover and occurrence frequency, the five dominant plants were heath aster (Aster ericoides), eastern gammagrass (Tripsacum dactyloides), little bluestem (Schizachyrium scoparium), sensitive briar (Schrankia roemeriana) and meadow dropseed (Sporobolus asper). Sixty-one percent of dickcissel nests were constructed on or immediately next to three plant species: eastern gammagrass, sensitive briar and green milkweed.
Date: May 1993
Creator: Steigman, Kenneth Lee
System: The UNT Digital Library
Biodiversity of Dragonflies and Damselflies (Odonata) of the South-Central Nearctic and Adjacent Neotropical Biotic Provinces (open access)

Biodiversity of Dragonflies and Damselflies (Odonata) of the South-Central Nearctic and Adjacent Neotropical Biotic Provinces

The south-central United States serves as an important biogeographical link and dispersal corridor between Nearctic and Neotropical elements of western hemisphere odonate faunas. Its species are reasonably well known because of substantial collections, but there has been no concerted effort to document the extent of biodiversity and possible geographic affinities of dragonflies and damselflies of this region. The recent discoveries of Argia leonorae Garrison, Gomphus gonzalezi Dunkle and Erpetogomphus heterodon Garrison from southern and western Texas and northern Mexico suggest that Odonata species remain to be discovered in this area, particularly from far south Texas and northern Mexico. I have documented a total of 12,515 records of Odonata found in 408 counties within the south-central U.S. A total of 73 species of damselflies and 160 species of dragonflies was revealed in the region. The 233 (197 in Texas) Odonata species are distributed among 10 families and 66 genera. Illustrated family, generic, and species-level keys are provided. Since the beginning of this work in the Fall of 1993, one species has been added each to the Louisiana and Oklahoma faunas, and 12 species have been added, previously unreported from Texas, including four new to the U.S. The area of highest Odonata …
Date: May 1999
Creator: Abbott, John C.
System: The UNT Digital Library
A Serological Investigation of Actinomycetes as a Preliminary to Taxonomic Study (open access)

A Serological Investigation of Actinomycetes as a Preliminary to Taxonomic Study

This thesis is a serological investigation of actinomycetes as a preliminary to taxonomic study.
Date: January 1959
Creator: Hamilton, Lawrence Edwin
System: The UNT Digital Library
A Technique for the Mass Culture of Aquatic Actinomycetes (open access)

A Technique for the Mass Culture of Aquatic Actinomycetes

The purpose of the problem was to develop a laboratory technique for mass culturing of the aquatic actinomycetes. In order to solve the problem, it was necessary to devise a suitable culture chamber that would nurture the various species in both primary and secondary stages. It was also important to provide an adequate medium for growth of these organisms. Finally, the construction of the culture chambers must provide for a continuous exhaust of the taste and odor compounds so that the production of these components could be correlated with growth stages.
Date: 1957
Creator: Norman, Mary Beth
System: The UNT Digital Library
Mitochondrial DNA Sequence Variation in Populations of the Nine-Banded Armadillo (Dasypus novemcinctus) (open access)

Mitochondrial DNA Sequence Variation in Populations of the Nine-Banded Armadillo (Dasypus novemcinctus)

Four populations of nine-banded armadillos, Dasypus novemcinctus, were investigated in the south-central United States in order to assess genetic variation in an isolated population (Electric Island, Lake Hamilton, Garland County, Arkansas); a semi-isolated population (Arkansas Post, Arkansas County, Arkansas), and two free ranging populations (southern Arkansas and central Texas). A 233 basepair sequence of the D-loop region of mitochondrial DNA was sequenced in individuals from each population. Individuals and populations were compared to assess relatedness among populations and individuals. Higher sequence diversity was detected in the semi-isolated population, while lower sequence diversity was observed in the isolated and free ranging populations. Overall, all populations exhibited low genetic variation when compared to genetic variation for other mammals. The results support the hypothesis that rapid range expansion combined with the organism's unique reproductive strategies have promulgated low genetic variation in the North American populations of nine-banded armadillos.
Date: August 2000
Creator: Elrod, Diana Adams
System: The UNT Digital Library
Anatomical and Morphological Responses of Cardiospermum Halicacabum L. (Balloon Vine), to Four Levels of Water Availability (open access)

Anatomical and Morphological Responses of Cardiospermum Halicacabum L. (Balloon Vine), to Four Levels of Water Availability

C. halicacabum (Sapindaceae) is an invasive plant that is considered a nuisance species in Texas riparian environments. Little is known of the tolerance of C. halicacabum to flooding and drought; however, this information may provide insight into the characteristics that contribute to C. halicacabum purported invasiveness. C. halicacabum seedlings (n = 92) were exposed to one of four levels of water availability (flooded, saturated, intermediate and dry) over six weeks under greenhouse conditions. Plant performance was affected by water availability; however, there was no effect on survivorship. Flooded and saturated plants exhibited morphological adaptations; producing adventitious roots, hypertrophy, and aerenchyma tissue. Morphological measures, anatomical responses, and patterns of biomass allocation all indicate that C. halicacabum is able to survive periodic inundation, perform in saturation, and establish and thrive on the drier end of a moisture gradient.
Date: May 2011
Creator: Dempsey, Matthew Anthony
System: The UNT Digital Library
Characterizing the Molecular Changes of Austrofundulus limnaeus As It Develops Towards and Enters Diapause II (open access)

Characterizing the Molecular Changes of Austrofundulus limnaeus As It Develops Towards and Enters Diapause II

Austrofundulus limnaeus is a species of annual killifish which inhabits ephemeral ponds in South America. The species is able to survive seasonally desiccating ponds due to their ability to produce robust embryos. The embryos of this species are capable of entering a developmental arrest, termed diapause II, which precedes the onset of drought. While in this arrested state embryos exhibit the greatest tolerance to anoxia of any characterized vertebrate at 25ºC. Furthermore, when raised at 30ºC, embryos escape the entrance to diapause II and go on to develop directly. Currently, little is known about the molecular mechanisms which induce and maintain this developmentally arrested state. In this study I have developed methods to analyze changes in histone modifications in the context of diapause II. Histone modifications were chosen due to their extreme conservation and well characterized role as modulators of gene expression in other systems. Results utilizing adapted immunobased assays show significant changes in the global amount of H3S10P, H3K27me and H3K4me, as the embryos progress from early embryogenesis through the exit of diapause. Additionally, it is revealed that there exists a degree of phenotypic plasticity with regards to the entrance into diapause II which is modulated by the environment …
Date: December 2015
Creator: Toni, Lee S.
System: The UNT Digital Library
Aryl Hydrocarbon Hydroxylase and Sixteen Alpha Hydroxylase in Cultured Human Lymphocytes (open access)

Aryl Hydrocarbon Hydroxylase and Sixteen Alpha Hydroxylase in Cultured Human Lymphocytes

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.
Date: December 1975
Creator: Coomes, Marguerite L.
System: The UNT Digital Library
Niche Structure of an Anole Community in a Tropical Rain Forest within the Choco Region of Colombia (open access)

Niche Structure of an Anole Community in a Tropical Rain Forest within the Choco Region of Colombia

Ten species of anoles at Bajo Calima within the Choco of Western Colombia separate into two principal microhabitat groups: forest species, and those inhabiting openings and edges. The ten anoles further separate according to ground and vegetation dwellers. There is a relation at Bajo Calima between the number of anole species and vegetational structural diversity. Anole diversity within a given macrohabitat is by perch microsite/microclimate heterogeneity. These are the two major ecological dimensions along which similarity is limited or resources are partitioned.
Date: May 1988
Creator: Castro-Herrera, Fernando
System: The UNT Digital Library
An Interpretation of Archaic Medical Treatises (open access)

An Interpretation of Archaic Medical Treatises

Ancient peoples did not distinguish between philosophy, religion, and science. Scientific truth did not exist apart from divine truth. Any new idea, finding, or theory was assimilated into a monolithic mythological structure. This is one of the causes of the underestimation of ancient science: it is always packaged in a myth - the method of preserving information in an oral culture. The mythological medium allowed the preservation and dissemination of hard-won, empirical, scientific knowledge through generations of preliterate peoples. The context for mythological memorization, or simply tradition, needed to be easily and naturally acquired. The ideal context was the anthropomorphic context, the ontogenic context. This is the Grand Allegory - the anthropomorphization of information. Biomyths are essentially biological texts allegorized in esoteric language.
Date: May 1993
Creator: Wagers, William D. (William Delbert)
System: The UNT Digital Library
Systematics of the Stonefly Tribe Suwalliini Surdick and Behavioral Studies of Selected Species in the Stonefly Families Chloroperlidae and Perlidae (open access)

Systematics of the Stonefly Tribe Suwalliini Surdick and Behavioral Studies of Selected Species in the Stonefly Families Chloroperlidae and Perlidae

The purpose of this study is to revise the genus Suwallia and to evaluate the potential taxonomic importance of adeagal and other genitalic characters, adult pigment patterns and egg characters. The revision concentrates on western North American species while providing coverage of all species, except Suwallia asiatica Zhiltzova and Lavanidova where only presumed females have been available for study. Communication and mate locating behaviors in adult stoneflies are critical for life cycle completion and species perpetuation. Drumming signals are known for numerous species of Plecoptera, but mate searching patterns and specifically, if or how vibrational communication is utilized for locating mates are virtually unknown for all stonefly species. I conducted field or laboratory studies of three species to elucidate mate searching patterns and how vibrational communication is used for locating mates. The species studied included a bushtopper, Suwallia pallidula (Banks); a ground scrambler, Claassenia sabulosa (Banks); and treetopper, Perlinella drymo (Newman). The "fly-tremulate-search". "rock to rock" and "fly-drum-search" search patterns exhibited by these species are described, as well as how vibrational communication is used for mate finding. Vibrational signal production by tremulation is reported for the first time in Suwallia, and for only the second time Plecoptera.
Date: August 1997
Creator: Alexander, Kevin D. (Kevin Dewayne)
System: The UNT Digital Library
Glucose and Altered Ceramide Biosynthesis Impact the Transcriptome and the Lipidome of Caenorhabditis elegans (open access)

Glucose and Altered Ceramide Biosynthesis Impact the Transcriptome and the Lipidome of Caenorhabditis elegans

The worldwide rise of diabetes and obesity has spurred research investigating the molecular mechanisms that mediate the deleterious effects associated with these diseases. Individuals with diabetes and/or obesity are at increased risk from a variety of health consequences, including heart attack, stroke and peripheral vascular disease; all of these complications have oxygen deprivation as the central component of their pathology. The nematode Caenorhabditis elegans has been established as a model system for understanding the genetic and molecular regulation of oxygen deprivation response, and in recent years methods have been developed to study the effects of excess glucose and altered lipid homeostasis. Using C. elegans, I investigated transcriptomic profiles of wild-type and hyl-2(tm2031) ( a ceramide biosynthesis mutant) animals fed a standard or a glucose supplemented diet. I then completed a pilot RNAi screen of differentially regulated genes and found that genes involved in the endobiotic detoxification pathway (ugt-63 and cyp-25A1) modulate anoxia response. I then used a lipidomic approach to determine whether glucose feeding or mutations in the ceramide biosynthesis pathway or the insulin-like signaling pathway impact lipid profiles. I found that gluocose alters the lipid profile of daf-2(e1370) (an insulin-like receptor mutant) animals. These studies indicate that a transcriptomic …
Date: August 2016
Creator: Ladage, Mary Lee
System: The UNT Digital Library
Responses of Selected Texas Fishes to Abiotic Factors, and an Evaluation of the Mechanisms Controlling Thermal Tolerance of the Sheepshead Minnow (open access)

Responses of Selected Texas Fishes to Abiotic Factors, and an Evaluation of the Mechanisms Controlling Thermal Tolerance of the Sheepshead Minnow

Low oxygen tolerances of ten fishes were estimated using an original nitrogen cascade design, and reciprocally transformed to express responses as ventilated volume necessary to satisfy minimal oxygen demand (L·mg O2^-1). Values ranged from 0.52 to 5.64 L·mg^-1 and were partitioned into three statistically distinct groups. Eight stream fishes showed moderately high tolerances reflecting metabolic adaptations associated with stream intermittency. Juvenile longear sunfish and two mollies comprised the second group. High tolerance of hypoxia may allow juvenile sunfish to avoid predation, and mollies to survive harsh environmental oxygen regimens. The sheepshead minnow was the most tolerant species of low oxygen, of those examined, explaining its presence in severely hypoxic environments.
Date: May 1994
Creator: Bennett, Wayne A. (Wayne Arden)
System: The UNT Digital Library
The stonefly genus Isogenoides Klapálek (Plecoptera: Perlodidae) of North America: Systematics, behavior and ecology. (open access)

The stonefly genus Isogenoides Klapálek (Plecoptera: Perlodidae) of North America: Systematics, behavior and ecology.

The stonefly genus Isogenoides is revised following a holomorphological approach utilizing traditional morphology and behavioral lines of evidence. Species keys are provided for all life stages. One species, I. krumholzi (Ricker) is considered a synonym of I. doratus (Frison). Detailed species descriptions are provided for males, females, nymphs and ova. Distributions are updated utilizing all known published accounts and materials examined. The vibrational communication (drumming) behavior is reported for males and all but one species for females. The signals were species-specific and ranged in complexity from ancestral sequenced duets to derived grouped exchanges. I. olivaceus is least specialized, having mostly sequenced duets, and I. zionensis most specialized, displaying ancestral sequenced, derived grouped and complex derived exchanges containing both sequenced and grouped elements. Laboratory egg incubation experiments over a 2-4 year period show that Isogenoides has a great capacity for extended, sometimes-asynchronous diapause and hatching. The eggs of six species were incubated at a single, ca. simulated San Miguel River, Colorado, seasonal temperature regime. Direct hatch within two weeks occurred only for I. zionensis (Leopard Creek, Colorado) with small numbers hatching again after one, two, and four years. Eggs of I. doratus and I. varians hatched after an over summer, 3-5 …
Date: May 2005
Creator: Sandberg, John Burton
System: The UNT Digital Library