Digital Commons Network^™

The Effects Of Thyroid Hormone On Myosin Heavy Chain A-7 Production In Xenopus Laevis Tail And Leg Muscles, Andrew R. Noble

Honors Theses

The present research examines the expression of myosin heavy chain genes in muscle fibers in Xenopus laevis. Characteristically different muscle fibers are expressed before and after metamorphosis. The embryonic myosin proteins that are synthesized during the tadpole stages are replaced with adult myosin heavy chains at metamorphosis. At least one of the adult myosin genes, called A-7, is expressed only in the adult animals, not in tadpoles. The controlling factor or trigger for the expression of this adult gene still remains unknown. There are a number of possible explanations for the A-7 regulation at metamorphosis, including changes in particular hormone …

Sperm Competition And Sex Allocation In Simultaneous Hermaphrodites, Eric Charnov

Biology Faculty & Staff Publications

Sex allocation theory is developed for hermaphrodites having frequent copulations and long-term sperm storage. Provided the sperm displacement mechanisms are similar to those known in insects, the ESS allocation to sperm versus eggs satisfies a rather simple rule. There are no data to test this rule, as yet.

Genetic Variability And Gene Flow In Metepeira Ventura (Araneae, Araneidae), Martina G. Ramirez

Biology Faculty Works

Levels of genetic variability and gene flow among three populations of Metepeira ventura o n Santa Catalina Island, California, were evaluated based on variation at 10 gene loci . Mean heterozygosity (observed) per population was 10 .4% and mean polymorphism was 36 .7%, consistent with levels of variabilit y in other arthropods. Values of FST for the five polymorphic loci (mean FST = 0 .009) suggest that gene flow prevents the genetic differentiation of these populations . The average number of migrants per generation (Nm) among these populations is estimated to be 28 .6 . The lack of inter-population genetic …

The Arabidopsis Homeotic Genes Apetala3 And Pistillata Are Sufficient To Provide The B Class Organ Identity Function, Beth A. Krizek, Elliot M. Meyerowitz

Faculty Publications

The class B organ identity genes, APETALA3 and PISTILLATA, are required to specify petal and stamen identity in the Arabidopsis flower. We show here that the activities of these two genes are sufficient to specify petals and stamens in flowers, in combination with the class A and C genes, respectively. Flowers of plants constitutively expressing both PISTILLATA and APETALA3 under the control of the 35S promoter from cauliflower mosaic virus consist of two outer whorls of petals and inner whorls of stamens. These plants also exhibit vegetative phenotypes that are not present in either of the singly (APETALA3 …

Leptodactylus Silvanimbus (Amphibia: Anura: Leptodactylidae): Natural History Notes, Advertisement Call, And Relationships, W. Ronald Heyer, Rafael O. De Sá, James R. Mccranie, Larry David Wilson

Biology Faculty Publications

In July 1995, we visited two of the three previously known localities for Leprodactylus silvanimbus in Departamento de Ocotepeque, Honduras. We found a new breeding site for the species, recorded its advertisement call, and collected and observed its adults and larvae. The purpose of this paper is to present the results of these new findings and to comment on the relationships L. silvanimbus.

Electromyographic Comparison Of Internal And External Obliques Using A Modified Version Of Kendall's Strength Test Positions For Upper And Lower Abdominals, Rebecca A. Currier, Margie L. Johnson

Masters Theses

The purpose of this study was to examine the activity of the internal obliques (upper abdominals) versus the external obliques (lower abdominals) during a modified version of Kendall's upper and lower abdominal strength tests using surface electromyography on adults. The study was not correlated to Kendall's theory due to the necessity to have the internal oblique electrode placed on the anterior abdomen. Twenty-four women and sixteen men participated in the study. All subjects were taught two positions ("easy" and "hard") for both abdominal tests and performed eight trials. A normalized ratio was generated by dividing one "hard" trial by the …

Características De La Osificación Craneal En Phyllomedusa Boliviana (Anura: Hylidae), Rafael O. De Sá, E. O. Lavilla

Biology Faculty Publications

RESUMEN. Dentro de la familia Hylidae disponemos de información sobre las secuencias de osificación craneal para menos del 4.0% de sus miembros. El presente trabajo describe la secuencia de osificación craneal de Phyllomedusa boliviana. El patrón general de osificación es similar a lo reportado para otras especies de la familia, pero existen algunas diferencias importantes tales como la osificación tardía de los próoticos y la osificación premetamórfica de neopalatino, vómer, cuadrado-yugal, pterigoides y columela. El lento desarrollo ulterior de la osificación resulta en juveniles con cráneos extensamente cartilaginosos.

ABSTRACT. Characteristics of the cranial ossification in Phyllomedusa …

Hyla Multifasciata, Rafael O. De Sá

Biology Faculty Publications

Hyla multifasciata is a medium to large species in the albopunctata species group, adults ranging in size from 42 - 61 mm SVL (mean male SVL = 48 mm, mean female SVL = 53 mm). The head is longer than wide. The snout is rounded in dorsal view, whereas in lateral view it is rounded and protrudes slightly beyond the mandible. The canthus rostralis is rounded and distinct, the loreal region is concave, and the internarial region is convex. The eyes are large, approximately twice the diameter of the tympanum. The tympanum is separated from the eye by a distance …

Monte Carlo Experiments And The Defense Of Diffusion Models In Molecular Population Genetics, Michael Dietrich

Dartmouth Scholarship

In the 1960s molecular population geneticists used Monte Carlo experiments to evaluate particular diffusion equation models. In this paper I examine the nature of this comparative evaluation and argue for three claims: first, Monte Carlo experiments are genuine experiments: second, Monte Carlo experiments can provide an important means for evaluating the adequacy of highly idealized theoretical models; and, third, the evaluation of the computational adequacy of a diffusion model with Monte Carlo experiments is significantly different from the evaluation of the empirical adequacy of the same diffusion model.

Afferent And Efferent Connections Of The Octavolateral Cerebellum In The Channel Catfish, Ictalurus Punctatus, Richard C. Rayborn

Master's Theses

No abstract provided.

The Distribution Of Gamma-Aminobutyric Acid (Gaba) And Glutamate In The Electrosensory System Of The Channel Catfish, Ictalurus Punctatus, Christian M. Fay

Master's Theses

No abstract provided.

Mutations In Trans-Acting Factors Affecting Mrna Decapping In Saccharomyces Cereviciae, Lianna K. Etchberger, C. A. Stevens, A. Stevens, R. Parker

Biology Faculty Publications

The decay of several yeast mRNAs occurs by a mechanism in which deadenylation precedes decapping and subsequent 5'-to-3' exonucleolytic decay. In order to identify gene products required for this process of mRNA turnover, we screened a library of temperature-sensitive strains for mutants with altered mRNA degradation. We identified seven mutations in four genes that inhibited mRNA turnover. Two mutations were alleles of the XRN1 5'-to-3' exoribonuclease known to degrade mRNAs following decapping. One mutation defined a new gene, termed DCP1, which in subsequent work was demonstrated to encode a decapping enzyme or a necessary component of a decapping complex. The …

Fate Of Biological Control Introductions: Monitoring An Australian Fungal Pathogen Of Grasshoppers In North America, Michael J. Bidochka, Scott R. A. Walsh, Mark E. Ramos, Raymond J. St. Leger, Julie Cl Silver, Donald W. Roberts

Biology Faculty Publications

In North America there are two generally recognized pathotypes (pathotypes 1 and 2) of the fungus Entomophaga grylli which show host-preferential infection of grasshopper subfamilies. Pathotype 3, discovered in Austra- lia,hasabroadergrasshopperhostrangeandwasconsidered to be a good biocontrol agent. Between 1989 and 1991 patho- type3wasintroducedattwofieldsitesinNorthDakota.Since resting spores are morphologically indistinguishable among pathotypes, we used pathotype-specific DNA probes to con- firm pathotype identification in E. grylli-infected grasshop- pers collected at the release sites in 1992, 1993, and 1994. In 1992, up to 23% of E. grylli-infected grasshoppers of the subfamilies Melanoplinae, Oedipodinae, and Gomphocerinae were infected by pathotype 3,with no infections >1 km …

Comparison Of The Effects Of Aerobic Dance To Water Aerobic Training On Maximal Oxygen Consumption, Terri L. Bedford, Tamara A. Dusterwinkle, Darcy J. Hoppman

Masters Theses

Water aerobics is one mode of exercise that is gaining popularity. Water aerobics allows adults who participate in an exercise program to improve their cardiorespiratory fitness. The purpose of this study was to determine if water aerobic training is as effective as land dance aerobic training in improving cardiorespiratory fitness in sedentary healthy adults. Eighteen subjects participated in this study; nine in dance aerobics and nine in water aerobics. Before and after eight weeks of training, subjects performed a graded maximal exercise test on a Schwinn Air-Dyne while maximal oxygen uptake was measured via a Beckman Metabolic Cart. ANCOVA was …

The Effects Of High Colony Density On Filtration, Mortality And Behavior In The Zebra Mussel, Dreissena Polymorpha, Christopher A. Call

Master's Theses

No abstract provided.

Density Dependent Limitations And Vertical Position Of Diatoms In A Periphyton Mat, Ronald E. Johnson

Master's Theses

No abstract provided.

Sculpins As Predators Of Lake Trout Eggs And Larvae: An Assessment Of Their Predatory Capabilities And Constraints, Heather C. Biga

Master's Theses

No abstract provided.

The Role Of Protein Kinases In The Regulation Of The Na+/H+ Antiporter In Xenopus Oocytes, Andre P. J. Kulisz

Master's Theses

No abstract provided.

Microglial Reactivity To N-Methyl-D-Aspartate (Nmda) Induced Excitotoxicity In The Immature Rat Brain, Laia Acarin

Master's Theses

No abstract provided.

Development Of A New Hydroseeding Process For Soil Stabilisation And Vegetation, Eileen T. Keane

Theses

A variety of mechanical and chemical extraction procedures were used to produce crude alginate gels from 3 seaweed species. These viscous hydrocolloidal substances had excellent adhesive properties but did however prove phytotoxic to germinating seeds. Experimental gels were subsequently refined and germination trials were carried out to determine optimum gel types. Pilot field trials were set up to compare the 2 most favourable gels with existing commercial hydroseeding products imported from Norway and Sweden. These tests involved the use of experimental plots on loam and sand substrates with slopes of 0^, 22^ and 45^. A number of biodegradable organic substances …

Intraspecific Life History Variation In Sceloporus Undulatus: A Factor Analysis, Geoffrey R. Smith, John W. Rowe, R. E. Ballinger

Faculty Publications

No abstract provided.

Stress Corrosion And Stress Induced Surface Morphology Of Epitaxial Films, Michael Grinfeld

Scanning Microscopy

In addition to several new predictions, the general theory of thermodynamic stability of heterogeneous systems with rearrangement has allowed us to understand the roots of several experimental and theoretical results of the past. One of them is an outstanding paper of Asaro and Tiller on stress corrosion cracking by surface diffusion published two decades ago. We compare results of Asaro and Tiller with conclusions of thermodynamic theory of solids with rearrangement and develop some Asaro-Tiller results in the directions dictated by the needs of thin films technology and experiment. A surface diffusion model in a prestressed elastic solid is studied …

Utilization Of An Electron-Beam Tester For Determining Internal Electric Field Profiles In Micro-Structured Thin-Film Semiconductor Devices, A. Jank, M. Jung, M. Lambert, G. Lichter, H. Schmoranzer

Scanning Microscopy

An electron-beam tester was used to determine the depth profile of the internal potential distribution in an a-Si:H solar cell and hence the internal electric field profile. The a-Si:H solar cells were prepared for the measurements with the electron-beam tester by low-energy chemical plasma beam etching through a plasma-resistant mask structured by electron-beam lithography. In contrast to an earlier work, the solar cells were in situ illuminated and the electric field profiles were determined for new, degraded and in situ annealed solar cells at various cell temperatures. The measuring results demonstrate that the electron-beam testing technique in combination with a …

Comparative Scanning, Transmission And Atomic Force Microscopy Of The Microtubular Cytoskeleton In Fenestrated Liver Endothelial Cells, Filip Braet, Ronald De Zanger, Wouter Kalle, Anton Raap, Hans Tanke, Eddie Wisse

Scanning Microscopy

Endothelial fenestrae control the exchange of fluids, solutes and particles between the sinusoidal lumen and the microvillous surface of the parenchymal cells. Fenestrae have a critical dimension in the order of 150-200 nm, making it necessary to use microscopes with a resolution better than the light microscope. Comparative whole-mount preparations of isolated, purified and cultured rat liver sinusoidal endothelial cells (LEC) were studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM). Examination of detergent-extracted LEC by SEM and TEM shows an integral cytoskeleton: sieve plates are delineated by a sieve plate-associated cytoskeleton ring and …

Characterizing The Outlines Of Degraded Fine-Particles By Fractal Dimension, Andrew Hunt, David L. Johnson

Scanning Microscopy

Fractal dimension has been used extensively as a descriptor of the rugged outlines of fine-particles. Potentially, it may be a useful parameter for characterizing the outlines of fine-particles which have been subjected to some form of chemical degradation. Here, fractal dimension values have been computed for the outlines of microscopic lead fine-particles both before and after weak hydrochloric acid dissolution experiments. Values obtained for the post-dissolution rugged profiles were greater than those of the pristine fracture grains which had a Euclidean form. The profiles of the degraded fine-particles could be characterized by a single fractal dimension value, or they exhibited …

Recognition And Phagocytosis Of Apoptotic Cells, Luciana Dini, Maria Teresa Ruzittu, Laura Falasca

Scanning Microscopy

Physiological elimination of unwanted cells within the organism occurs via cell death by apoptosis and phagocytosis of these cells represents a key event in the apoptotic process. Macrophages, which are the dedicated phagocytes, and other occasionally phagocytic cells ingest the apoptotic cells while they are still intact, thus preventing the leakage of potentially harmful materials from the dying cells. Although evidence has been presented that the elimination of apoptotic bodies from the tissue operates by means of specific recognition systems, the molecular mechanisms by which an apoptotic cell is recognized are poorly understood. Recent data indicate that phagocyte recognition of …

Scanning Electron Microscopic Study Of The Postnatal Development Of The Rabbit Cochlea, With An Emphasis On Innervation, Hirofumi Morita, Tomoyuki Hoshino, Kunihiro Mizuta, Satoshi Iwasaki

Scanning Microscopy

The development of nerve fiber arrangements of the organ of Corti was studied in rabbits 1, 3, 5, 7 and 12-days-old using thick sections from celloidin-embedded cochleas which were examined under a scanning electron microscope. The arrangements of nerve fibers varied with developmental age. The tunnel spiral bundle was thick and loosely collected in the immature cochlea. The outer spiral fibers were recognized even in the narrow space of Nuel in the one-day-old cochlea. As Nuel's space is extending, the fibers course along the medial side of Deiters' cells. The arrangement of the outer spiral fibers was irregular and sparse …

The Structure Of The G Protein Heterotrimer GIα1Β1Γ2, Mark A. Wall, David E. Coleman, Ethan Lee, Jorge A. Iñiguez-Lluhi, Bruce A. Posner, Alfred G. Gilman, Stephen R. Sprang

Biological Sciences Faculty Publications

The crystallographic structure of the G protein heterotrimer G_iα1(GDP)β₁γ₂ (at 2.3 A) reveals two nonoverlapping regions of contact between α and β, an extended interface between β and nearly all of γ, and limited interaction of α with γ. The major α/β interface covers switch II of α, and GTP-induced rearrangement of switch II causes subunit dissociation during signaling. Alterations in GDP binding in the heterotrimer (compared with α-GDP) explain stabilization of the inactive conformation of α by βγ. Repeated WD motifs in β form a circularized sevenfold β propeller. The conserved cores of these …

Volume Determination Of Human Metaphase Chromosomes By Scanning Force Microscopy, Wolfgang Fritzsche, Eric Henderson

Scanning Microscopy

The scanning force microscope (SFM) yields the topography of the investigated surface. A procedure was developed which starts from this three-dimensional information to estimate the volume of a biological specimen. The volume of spread human metaphase chromosomes was determined in air and rehydrated in aqueous buffer. A difference of the determined volume of a air-dried metaphase chromosome set was found compared to values from electron microscopic investigations, and could be correlated with differences in the hydration state of the chromosomes. SFM-based relative volumes of air-dried chromosomes resembles literature data regarding volume range and distribution. Possible application of SFM-based relative volume …

The Phase Effect In Electronic Stopping: A Survey Of The Contributing Physical Processes, P. Bauer, E. Steinbauer, F. Kastner

Scanning Microscopy

The phase effect in electronic stopping deals with the question whether the energy loss of an ion due to the interaction with electrons depends on the state of aggregation of the target. It is commonly accepted that charge changing collisions of the projectile and changes in the electronic states of the target contribute to the phase effect In addition, the energy loss measurements might possibly be influenced by different impact parameter selection in the two experiments (solid and gas phase). Quantitative results of our calculations show that generally the impact parameter selection inherently present in a transmission experiment is quenched …