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Suppression Efficiency (suppression + efficiency)
Selected AbstractsN-terminal extension of Saccharomyces cerevisiae translation termination factor eRF3 influences the suppression efficiency of sup35 mutationsFEMS YEAST RESEARCH, Issue 3 2007Kirill Volkov Abstract The eukaryotic translation termination factor eRF3 stimulates release of nascent polypeptides from the ribosome in a GTP-dependent manner. In most eukaryotes studied, eRF3 consists of an essential, conserved C-terminal domain and a nonessential, nonconserved N-terminal extension. However, in some species, this extension is required for efficient termination. Our data show that the N-terminal extension of Saccharomyces cerevisiae eRF3 also participates in regulation of termination efficiency, but acts as a negative factor, increasing nonsense suppression efficiency in sup35 mutants containing amino acid substitutions in the C-terminal domain of the protein. [source] The HAL3-PPZ1 dependent regulation of nonsense suppression efficiency in yeast and its influence on manifestation of the yeast prion-like determinant [ISP+]GENES TO CELLS, Issue 4 2007Anna Aksenova The efficiency of stop codons read-through in yeast is controlled by multiple interactions of genetic and epigenetic factors. In this study, we demonstrate the participation of the Hal3-Ppz1 protein complex in regulation of read-through efficiency and manifestation of non-Mendelian anti-suppressor determinant [ISP+]. Over-expression of HAL3 in [ISP+] strain causes nonsense suppression, whereas its inactivation displays as anti-suppression of sup35 mutation in [isp,] strain. [ISP+] strains carrying hal3, deletion cannot be cured from [ISP+] in the presence of GuHCl. Since Hal3p is a negative regulatory subunit of Ppz1 protein phosphatase, consequences of PPZ1 over-expression and deletion are opposite to those of HAL3. The observed effects are mediated by the catalytic function of Ppz1 and are probably related to the participation of Ppz1 in regulation of eEF1B, elongation factor activity. Importantly, [ISP+] status of yeast strains is determined by fluctuation in Hal3p level, since [ISP+] strains have less Hal3p than their [isp,] derivatives obtained by GuHCl treatment. A model considering epigenetic (possibly prion) regulation of Hal3p amount as a mechanism underlying [ISP+] status of yeast cell is suggested. [source] Fat suppression with short inversion time inversion-recovery and chemical-shift selective saturation: A dual STIR-CHESS combination prepulse for turbo spin echo pulse sequencesJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 5 2010Koji Tanabe DDS Abstract Purpose: To test a newly developed fat suppression magnetic resonance imaging (MRI) prepulse that synergistically uses the principles of fat suppression via inversion recovery (STIR) and spectral fat saturation (CHESS), relative to pure CHESS and STIR. This new technique is termed dual fat suppression (Dual-FS). Materials and Methods: To determine if Dual-FS could be chemically specific for fat, the phantom consisted of the fat-mimicking NiCl2 aqueous solution, porcine fat, porcine muscle, and water was imaged with the three fat-suppression techniques. For Dual-FS and STIR, several inversion times were used. Signal intensities of each image obtained with each technique were compared. To determine if Dual-FS could be robust to magnetic field inhomogeneities, the phantom consisting of different NiCl2 aqueous solutions, porcine fat, porcine muscle, and water was imaged with Dual-FS and CHESS at the several off-resonance frequencies. To compare fat suppression efficiency in vivo, 10 volunteer subjects were also imaged with the three fat-suppression techniques. Results: Dual-FS could suppress fat sufficiently within the inversion time of 110,140 msec, thus enabling differentiation between fat and fat-mimicking aqueous structures. Dual-FS was as robust to magnetic field inhomogeneities as STIR and less vulnerable than CHESS. The same results for fat suppression were obtained in volunteers. Conclusion: The Dual-FS-STIR-CHESS is an alternative and promising fat suppression technique for turbo spin echo MRI. J. Magn. Reson. Imaging 2010;31:1277,1281. ©2010 Wiley-Liss, Inc. [source] | ||||||||||