Life Sciences Commons^™

Identification Of Factors Affecting Bovine Somatic Cell Nuclear Transfer Efficiency And Characterization Of Transcriptional Profiles Of Nuclear Transfer Embryos And Cotyledons, Kenneth Ivan Aston

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Since the production of the first sheep by somatic cell nuclear transfer a great deal of effort has been made to improve efficiency and to understand nuclear reprogramming mechanisms. Unfortunately efficiency remains low, and nuclear reprogramming mechanisms remain uncharacterized. The objectives of this research were to identify factors associated with somatic cell nuclear transfer efficiency and to analyze the transcriptome of blastocyst-stage clone and control embryos and cotyledonary tissue in an effort to elucidate mechanisms responsible for the low developmental efficiency and high post-implantation losses.

The experiments reported here identify factors including oocyte source and timing of activation following nuclear …

Analysis Of Distal-Less Gene Expression In Ciona Intestinalis, Michelle Cangiano

Senior Honors Projects

Several homeobox-containing genes related to Distal-less (Dlx/Dll) have been isolated from a wide variety of organisms and have been shown to function as developmental regulators. In Drosophila only one Distal-less gene has been identified so far, and in vertebrates many components of the Distal-less family have been characterized. This suggests that, during the evolution of the Chordate phylum, the Dlx genes arose from an ancestral Distal-less gene via gene duplication. Three Dll homeoboxes have been isolated from the protochordate Ciona intestinalis and their clustered arrangement has been described. Since Ciona is regarded as one of the most primitive extant chordates, …

Contributions Of Heterosis And Epistasis To Hybrid Fitness, Mitchell B. Cruzan

Biology Faculty Publications and Presentations

Early-generation hybrid fitness is difficult to interpret because heterosis can obscure the effects of hybrid breakdown. We used controlled reciprocal crosses and common garden experiments to distinguish between effects of heterosis and nuclear and cytonuclear epistasis among morphotypes and advanced-generation hybrid derivative populations in the Piriqueta caroliniana (Turneraceae) plant complex. Seed germination, growth, and sexual reproduction of first-generation hybrids, inbred parental lines, and outbred parental lines were compared under field conditions. Average vegetative performance was greater for hybrids than for inbred lines, and firstseason growth was similar for hybrids and outbred parental lines. Hybrid survival surpassed that of inbred lines …

Monitoring Immediate-Early Gene Expression Through Firefly Luciferase Imaging Of Hrs/J Hairless Mice, Michael E. Geusz, Anne M. Collaco

Biological Sciences Faculty Publications

Background: Gene promoters fused to the firefly luciferase gene (luc) are useful for examining gene regulation in live transgenic mice and they provide unique views of functioning organs. The dynamics of gene expression in cells and tissues expressing luciferase can be observed by imaging this enzyme's bioluminescent oxidation of luciferin. Neural pathways involved in specific behaviors have been identified by localizing expression of immediate-early genes such as c-fos. A transgenic mouse line with luc controlled by the human c-fos promoter (fos::luc) has enabled gene expression imaging in brain slice cultures. To optimize imaging of immediate-early gene expression throughout intact mice, …

Enhancer Trapping Reveals Widespread Circadian Clock Transcriptional Control In Arabidopsis, Todd P. Michael, C Robertson Mcclung

Dartmouth Scholarship

The circadian clock synchronizes the internal biology of an organism with the environment and has been shown to be widespread among organisms. Microarray experiments have shown that the circadian clock regulates mRNA abundance of about 10% of the transcriptome in plants, invertebrates, and mammals. In contrast, the circadian clock regulates the transcription of the virtually all cyanobacterial genes. To determine the extent to which the circadian clock controls transcription in Arabidopsis, we used in vivo enhancer trapping. We found that 36% of our enhancer trap lines display circadian-regulated transcription, which is much higher than estimates of circadian regulation based on …

Quorum Sensing In Gram-Negative Bacteria, Gülgün Boşgelmez Tinaz

Turkish Journal of Biology

It has become increasingly and widely recognised that bacteria do not live as isolated entities but instead exist as communities that exploit elaborate systems of intercellular communication to facilitate their adaptation to changing environmental conditions. A well-characterised example of such intercellular communication is quorum sensing. Quorum sensing depends on the production of diffusible signal molecules termed autoinducers or pheromones, which enable a bacterium to monitor its own cell population density. A variety of physiological processes in a range of bacterial species is regulated by quorum sensing. Examples include bioluminescence, antibiotic biosynthesis, swarming, biofilm differentiation, conjugation and the production of virulence …

Role Of Calcium Oxalate Monohydrate Crystal Interactions With Renal Epithelial Cells In The Pathogenesis Of Nephrolithiasis: A Review, John C. Lieske, Mary S. Hammes, F. Gary Toback

Scanning Microscopy

Renal tubular fluid in the distal nephron is supersaturated with calcium and oxalate ions that nucleate to form crystals of calcium oxalate monohydrate (COM), the most common crystal in renal stones. How these nascent crystals are retained in the nephron to form calculi in certain individuals is not known. Recent studies from this laboratory have demonstrated that COM crystals can bind within seconds to the apical surface of renal epithelial cells, suggesting one mechanism whereby crystals could be retained in the tubule. Adherence of crystals to cells along the nephron may be opposed by specific urinary anions such as glycosaminoglycans, …

Use Of Microprojectile Bombardment In Transient Expression Assays To Analyze Protochlorophyllide Reductase Gene Expression In Greening Maize Seedling Leaf Cells, Jennifer J. Marden

Senior Scholar Papers

In young cells of leaf meristems the progenitors of chloroplasts are small organelles known as proplastids, which divide and differentiate into chloroplasts. However, in the absence of light, proplastids undergo a different sequence of development and become etioplasts. When light is supplied to etiolated plants during the "greening" process, etioplasts differentiate into chloroplasts containing chlorophyll. An important light dependent step in chlorophyll biosynthesis is the photoreduction of protochlorophyllide to chlorophyllide by the NADPH:protochlorophyllide reductase (PCR) enzyme. This enzyme is present at high activity only in etiolated tissue and during early stages of light-induced chlorophyll synthesis. The enzyme and its corresponding …