A technology for detecting unselected mutational spectra in human genomic DNA

Thesis (Ph. D.)--Massachusetts Institute of Technology, Division of Bioengineering and Environmental Health, 1999.Includes bibliographical references (leaves 186-205).by Xiaocheng Li-Suckoleiki.Ph.D

Mutant Versions of the S. cerevisiae Transcription Elongation Factor Spt16 Define Regions of Spt16 That Functionally Interact with Histone H3

In eukaryotic cells, the highly conserved FACT (FAcilitates Chromatin Transcription) complex plays important roles in several chromatin-based processes including transcription initiation and elongation. During transcription elongation, the FACT complex interacts directly with nucleosomes to facilitate histone removal upon RNA polymerase II (Pol II) passage and assists in the reconstitution of nucleosomes following Pol II passage. Although the contribution of the FACT complex to the process of transcription elongation has been well established, the mechanisms that govern interactions between FACT and chromatin still remain to be fully elucidated. Using the budding yeast Saccharomyces cerevisiae as a model system, we provide evidence that the middle domain of the FACT subunit Spt16 – the Spt16-M domain – is involved in functional interactions with histone H3. Our results show that the Spt16-M domain plays a role in the prevention of cryptic intragenic transcription during transcription elongation and also suggest that the Spt16-M domain has a function in regulating dissociation of Spt16 from chromatin at the end of the transcription process. We also provide evidence for a role for the extreme carboxy terminus of Spt16 in functional interactions with histone H3. Taken together, our studies point to previously undescribed roles for the Spt16 M-domain and extreme carboxy terminus in regulating interactions between Spt16 and chromatin during the process of transcription elongation

High-speed microemulsion chromatography.

NoIn previous reports of microemulsion electrokinetic chromatography (MEEKC), analysis times were typically in the order of 10 min as high-ionic strength buffers were used. These buffers produced high currents which limit the voltages which can be applied, therefore, analysis times could not be reduced. The primary cause of the high-ionic strength is the relatively high concentrations of surfactants required to form the microemulsion. The surfactant concentration can be lower when using an oil with a smaller surface tension. This preliminary study showed that migration times in MEEKC can be reduced to below 1 min by using a combination of an optimum microemulsion composition, high voltage, high temperature, short capillaries by injecting via the short end, or by simultaneously applying pressure and voltage. Long injection sequences and quantitation were found to be possible with minimum buffer depletion effects

Synthesis of symmetric dinitro-functionalised Tröger's base analogues

The synthesis of six new examples of 2,8-dinitro-substituted Tröger's base analogues are reported, together with the first examples of 1,7-, 3,9- and 4,10-dinitro Tröger's base analogues and the first example of a tetranitro Tröger's base compound. Several of these dinitro compounds lack substituents at the 2- and 8-positions and therefore provide further examples of Tröger's base analogues derived from anilines lacking a para substituent