Browsing by Subject "Tissue"
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Item Characterization of maize genes that exhibit present-absent expression in different genotypes.(2010-12) Chakravartty, MoumitaMaize inbred lines exhibit high levels of gene expression diversity. Several hundred genes exhibit severe expression variation such that the transcript is detected only in one inbred and absent in another. However, the frequency, types of genes affected and potential causes for these “present-absent” (PA) expression patterns in maize inbred lines are not well characterized. Microarray analyses of gene expression patterns in 11-day old seedlings, ear, embryo, and endosperm tissues from two maize inbred lines, B73 and Mo17, identified 570 genes (out of 17000) with PA expression patterns in at least one tissue type. Over 55% of the PA genes exhibit “constitutively absent expression” in which one of the two genotypes exhibits lack of expression in all tissues tested. The remaining PA genes exhibit “tissue specific absent expression” where a gene exhibits present-absent expression in some tissues and present-present expression in at least one other tissue types studied. Many of the PA genes are maize-specific sequences that do not have orthologues in other plant species and the majority of the remaining PA genes are members of gene families. Using existing eQTL and aCGH datasets, we found that PA expression differences are primarily caused by differential regulation rather than by differences in gene content. Collectively, our analysis documented a high frequency of genes that are expressed in some maize lines but not others and suggests that many of these changes are due to trans-regulatory variation.Item Characterizing the Mechanical Properties of Biological Tissues(2019-11-12) Wallace, Niko JThis research provides information indicating individual pixel strains can be calculated via a uniaxial test to map the mechanical properties of tissue including the anisotropic nature of diseased tissue.Item Development of capillary electrophoretic-based techniques to analyze doxorubicin in tissues, cells and subcellular fractions.(2010-09) Wang, YaohuaDoxorubicin (DOX) is a widely used anti-cancer drug. It is hypothesized that the efficacy and toxicity of DOX is related to its distribution and metabolism. Capillary electrophoresis (CE) including its variants such as micellar electrokinetic chromatography (MEKC) is becoming a popular method in bioanalysis due to its high sensitivity and separation efficiency, small sample size requirements, simple sample preparation procedures, versatility in sampling and short separation times. The goal of this thesis is to take advantage of these features and develop CE-based methods to investigate the metabolism, subcellular distribution and localization of DOX in biological samples after DOX treatments. A direct sampling technique was developed to quantify DOX at or near the tumor site in hepatocellular carcinoma tissues after chemoembolization. This technique allows for sampling small volume of tissues (<10 picoliters) selectively from adjacent tumor and non-tumor regions with high spatial resolution (100 micrometers) and reproducibility. Using this technique coupled with MEKC-LIF (laser-induced fluorescence detection), DOX was detected and quantified, in both tumor and non-tumor regions in resected human livers. A MEKC method was developed to monitor the incorporation, transformation and subcellular metabolism of a DOX prodrug, N-L-leucyl-doxorubicin (LeuDOX), which is expected to have higher efficacy and lower toxicity. It successfully separated LeuDOX from DOX and its major metabolite, doxorubicinol (DOXol). The metabolism of LeuDOX in four subcellular fractions of human uterine sarcoma cells suggested that LeuDOX is mainly activated to DOX in the lysosome-enriched fraction which contains hydrolytic enzymes. Metabolism of DOX in isolated subcellular fractions from young and old rat livers was investigated by MEKC-LIF, suggesting that this technique is adequate to investigate the effect of aging on the metabolism of DOX at the subcellular level. The study showed that the young rat liver is more metabolic active than that of the old rat. In subcellular drug analysis, the purity of the subcellular fractions limits the determination of the subcellular localization of metabolites. Organelles with high purity and biological function are necessary to refine the understanding of DOX metabolism in a specific organelle type. An immunoisolation method based on the use of an antibody specific to a peroxisomal membrane protein was developed to isolate peroxisomes with low levels of contaminating mitochondria and lysosomes. The metabolism of DOX and a model compound, BODIPY fatty acid analog, showed possible peroxisomal biotransformation of these xenobiotics. The techniques and methodologies developed in the dissertation work would be the basis of future developments including assessing the function of new prodrugs at the cellular and subcellular levels, profiling subcellular specific metabolism and monitoring drug distribution and metabolism in tissue cross-sections. These measurements are necessary to understand the efficacy and toxicity of chemotherapy drug treatments in preclinical and clinical studies.Item The effect of radial convection on cell proliferation Iin bone tissue engineering(2009-04) Shao, WeiruLarge bone defects are frequently encountered during surgeries. Traditional methods of repair are limited by bone graft availability and increased surgical morbidity. Tissue engineered bone tissue has many clinical advantages. However, its current technology is limited by implant size and lacks of immediate nutritional perfusion once the tissue is implanted. Objective: To sustain cell growth and proliferation in a three-dimensional scaffold unit with radial convective flow. Material and Methods: Fetal rat calvarial cells were harvested and loaded into 1x1 cm hydroxyapatite cylinders. Microperforated hollow fibers were placed at the center of the cylinders to generate radial convective flow with oxygenated cell culture medium under hydraulic pressure. Live cell densities within the blocks were determined after 8 days of convection. Results: Radial convection sustained cell growth and proliferation better than simple diffusion at all three zones of the cylinders: center, outer, and rim. Conclusion: Radial convective flow is capable of supporting cellular function and proliferation in small scaffold units. The design of the radial convection units and their system parameters are validated by this study. The results are very useful to devise future tissue engineering studies involving radial convective flow.Item Light-mediated Sexual Dimorphism in Opsin Expression During Spawning in Nematostella vectensis(2024-04) Wagner, Starla J.; McCulloch, Kyle J.Across animals, opsins are the primary protein responsible for light detection. Currently, there is a large gap in knowledge in the evolutionary history of opsin function and how it correlates with other biological responses like spawning. Cnidarians (jellyfish and anemones) are prime candidates for closing this gap. They are a sister taxon to bilaterally symmetric animals like flies and humans, and so studying their opsin function and expression in non-visual contexts allows for further understanding of how light sensing may have evolved to form modern visual systems. In this experiment, qPCR analysis on the Cnidarian, Nematostella vectensis (the starlet sea anemone), was used to determine the effect of certain wavelengths of light that an animal was exposed to during spawning had on opsin expression levels. The impact of sex and tissue type on these expression levels was an additional area of interest. The data showed that certain wavelengths like blue light were correlated with larger amounts of opsin expression in female mesenteries and tentacles/skin tissue than in male tissue types. This indicates that opsin expression is sexually dimorphic which implies there is a relationship between opsin expression and spawning, something that was previously unknown. Future experiments using RNA-seq will allow for a deeper understanding of this relationship and the proteins involved.