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No description available.

The follicle cell-specific (FCS) gene, a 3,023 bp gene specific to follicle cells of the mosquito, Aedes aegypti, was characterized at the nucleotide level. Genomic Southern blots demonstrated that there was only one copy of this gene in the A. aegypti genome. An ovary-specific cDNA library was constructed from female mosquitoes 24 hours post blood meal. Then a cDNA clone containing the complete coding region was identified, and its nucleotide sequence was determined. The deduced protein contained unusually high levels of alanine and proline. Search of a protein data base revealed that the FCS gene was similar to Drosophila vitelline membrane protein genes, with 47.5% similarity in nucleotide sequence and 46.7% similarity in amino acid sequence. The conserved hydrophobic regions from several vitelline membrane proteins were compared. Another cDNA clone, 1D, was isolated from the cDNA library screened with the FCS gene. These two mosquito genes shared a 60% similarity at the nucleic acid level and a 79.8% similarity at the amino acid level.

Aneuploid plants are often used to locate genes or establish linkage, but first, they must be available. In Chrysanthemum cinerariaefolium Vis., a plant that produces pyrethrin, a relatively safe natural insecticide, aneuploids had not been categorized before. This research proposed to characterize aneuploids by morphology, cytology, nuclear DNA content, and pyrethrin composition. Aneuploid progeny of triploid parents were examined cytologically and morphologically. HPLC was used to establish pyrethrin composition and nuclear DNA content was calculated from flow cytometry. Five distinct phenotypes were found that may indicate aneuploid status, but not exact chromosome number. Exact chromosome number could only be distinguished cytologically, and ranged from 17 to 36, (2n = 18 for the diploid). Three trisomics were located. Nuclear DNA content indicated diploid or triploid status but not aneuploidy. Some of the aneuploids categorized may be useful in further research to locate pyrethrin genes or their linkages.

<p> Pregnane X receptor (PXR) is a major transcriptional regulator of xenobiotic metabolism and transport pathways in the liver and intestines, which are critical for protecting organisms against potentially harmful xenobiotic and endobiotic compounds. Inadvertent activation of drug metabolism pathways through PXR is known to contribute to drug resistance, adverse drug-drug interactions, and drug toxicity in humans. In both humans and rodents, PXR has been implicated in non-alcoholic fatty liver disease, diabetes, obesity, inflammatory bowel disease, and cancer. Because of PXR's important functions, it has been a therapeutic target of interest for a long time.</p><p> Recent mechanistic studies have shown that PXR is modulated by multiple PTMs. In this thesis work, we conducted the first detailed examination of PXR regulation by acetylation. We found that PXR is efficiently acetylated <i> in vitro</i> and <i>in vivo</i> in multiple cell lines (293T, HepG2, LS174T). Acetylation and deacetylation are mediated by p300 and SIRT1, respectively. We found that PXR is directly acetylated by p300 at K109 by LC-MS/MS analysis. The K109Q acetylation mimicking mutant displayed reduced transcriptional activity and reduced ability to induce <i>cyp3A4</i> target gene mRNA and protein compared to the WT and the K109R acetylation-defective mutant. The diminished activity of the K109Q mutant appears to be due to impaired heterodimerization with RXRa and impaired binding of the PXR-RXRa heterodimer to DNA response elements. Furthermore, PXR acetylation appears to have an effect at the phenotypic level, in that pharmacological modulation of PXR acetylation levels can modulate its lipogenic function in mouse primary hepatocytes independent of a ligand. Moreover, the K109Q mutant displays impaired chemoprotective function based on morphological assessment of cells overexpressing K109Q and challenged with indomethacin, suggesting that K109 acetylation downregulates PXR's chemoprotective and perhaps anti-apoptotic functions, although this must be explored further. Notably, the K109R mutant displayed the WT phenotype, further supporting that acetylation itself, not just any arbitrary mutation confers the effect. Altogether, the data suggests that acetylation at K109 represents an overall "loss of function" effect on PXR activity. Implications of our findings are discussed in the context of known roles for PXR in transcription, health, and disease.</p>

<p> The focus of the present research is the synthesis of polypeptides for the study of protein folding and misfolding and for the development of novel polypeptide-based optical antennas in nanotechnology. It is hypothesized that simple polypeptides can be used as models to mimic <i>in vivo</i> folding of globular proteins. Desired repetitive polypeptides were genetically encoded and expressed in <i>E. coli</i> using conventional methods and characterized using a variety of spectroscopic (including circular dichroism (CD), deep UV resonance Raman (DUVRR), UV-vis and fluorescence) and microscopic (atomic force microscopy (AFM) and transmission electron microscopy (TEM)) techniques. The polypeptides predominantly formed bilayer, fibrillar structures with a cross &beta;-core. <b>YEHK21-YE8</b>, a chimeric polypeptide, folded within three days. The folding/fibrillation of the chimeric construct illuminates the controlling factors and hence suggests the importance of those factors in amyloidogenic diseases. <b>YE8</b> and <b>YE8</b> derivatives illustrated the role of proline in &beta;-sheet formation. The EW polypeptide models elucidated the influence of tryptophan residues and the degree of polymerization on folding. The study of <b>EW14C1</b> and <b>EW21C1</b> demonstrated light-harvesting properties when labeled with a suitable dye.</p>