Contributions of ubiquitin- and PCNA-binding domains to the activity of Polymerase η in Saccharomyces cerevisiae

Bypassing of DNA lesions by damage-tolerant DNA polymerases depends on the interaction of these enzymes with the monoubiquitylated form of the replicative clamp protein, PCNA. We have analyzed the contributions of ubiquitin and PCNA binding to damage bypass and damage-induced mutagenesis in Polymerase η (encoded by RAD30) from the budding yeast Saccharomyces cerevisiae. We report here that a ubiquitin-binding domain provides enhanced affinity for the ubiquitylated form of PCNA and is essential for in vivo function of the polymerase, but only in conjunction with a basal affinity for the unmodified clamp, mediated by a conserved PCNA interaction motif. We show that enhancement of the interaction and function in damage tolerance does not depend on the ubiquitin attachment site within PCNA. Like its mammalian homolog, budding yeast Polymerase η itself is ubiquitylated in a manner dependent on its ubiquitin-binding domain

Coupling of frustrated Ising spins to magnetic cycloid in multiferroic TbMnO3

We report on diffraction measurements on multiferroic TbMnO3 which demonstrate that the Tb- and Mn-magnetic orders are coupled below the ferroelectric transition TFE = 28 K. For T < TFE the magnetic propagation vectors (tau) for Tb and Mn are locked so that tauTb = tauMn, while below TNTb = 7 K we find that tauTb and tauMn lock-in to rational values of 3/7 b* and 2/7 b*, respectively, and obey the relation 3tauTb - tauMn = 1. We explain this novel matching of wave vectors within the frustrated ANNNI model coupled to a periodic external field produced by the Mn-spin order. The tauTb = tauMn behavior is recovered when Tb magnetization is small, while the tauTb = 3/7 regime is stabilized at low temperatures by a peculiar arrangement of domain walls in the ordered state of Ising-like Tb spins.Comment: 5 pages, 3 figure

Sonographic evaluation of transjugular intrahepatic porto-systemic shunt

The purpose of this article is to review the role of sonography before, during and after transjugular intrahepatic portosystemic shunt placement. A sonographic assessment of the liver and abdomen is recommended before the procedure. We illustrate several important sonographic findings for the echographist, which may alter the procedure approach or even preclude transjugular intrahepatic portosystemic shunt placement. The most challenging step during the procedure is the puncture of the right portal vein. Sonography can be a helpful tool in reducing the number of needle passes, thereby reducing the risk of hemorrhagic complications. Because of its non-invasive and costbenefit nature, sonography is useful for transjugular intrahepatic portosystemic shunt follow-up. A baseline study at 24 to 48 hours is recommended to discover procedure-related complications. Long-term follow-up is important to detect malfunction of the shunt. Doppler ultrasound is very accurate in detecting shunt thrombosis. However, no consensus exists on the optimal sonographic screening protocol for detecting stenosis. We describe three sonographic parameters to detect transjugular intrahepatic portosystemic shunt stenosis with high sensitivity. Finally, additional sonographic parameters and potential pitfalls are provided in order to improve sensitivity

CT colonography with minimal bowel preparation: evaluation of tagging quality, patient acceptance and diagnostic accuracy in two iodine-based preparation schemes

PURPOSE: The aim of this study was to compare a 1-day with a 2-day iodine bowel preparation for CT colonography in a positive faecal occult blood test (FOBT) screening population. MATERIALS AND METHODS: One hundred consecutive patients underwent CT colonography and colonoscopy with segmental unblinding. The first 50 patients (group 1) ingested 7 50 ml iodinated contrast starting 2 days before CT colonography. The latter 50 patients (group 2) ingested 4 50 ml iodinated contrast starting 1 day before CT colonography. Per colonic segment measurements of residual stool attenuation and homogeneity were performed, and a subjective evaluation of tagging quality (grade 1-5) was done. Independently, two reviewers performed polyp and carcinoma detection. RESULTS: The tagging density was 638 and 618 HU (p = 0.458) and homogeneity 91 and 86 HU for groups 1 and 2, respectively (p = 0.145). The tagging quality was graded 5 (excellent) in 90% of all segments in group 1 and 91% in group 2 (p = 0.749). Mean per-polyp sensitivity for lesions >or=10 mm was 86% in group 1 and 97% in group 2 (p = 0.355). Patient burden from diarrhoea significantly decreased for patients in group 2. CONCLUSIONS: One-day preparation with meglumine ioxithalamate results in an improved patient acceptability compared with 2-day preparation and has a comparable, excellent image quality and good diagnostic performanc

Heritability and major gene effects on left ventricular mass in the Chinese population: a family study

BACKGROUND: Genetic components controlling for echocardiographically determined left ventricular (LV) mass are still unclear in the Chinese population. METHODS: We conducted a family study from the Chin-San community, Taiwan, and a total of 368 families, 1145 subjects, were recruited to undergo echocardiography to measure LV mass. Commingling analysis, familial correlation, and complex segregation analysis were applied to detect component distributions and the mode of inheritance. RESULTS: The two-component distribution model was the best-fitting model to describe the distribution of LV mass. The highest familial correlation coefficients were mother-son (0.379, P < .0001) and father-son (0.356, P < .0001). Genetic heritability (h(2)) of LV mass was estimated as 0.268 ± 0.061 (P < .0001); it decreased to 0.153 ± 0.052 (P = .0009) after systolic blood pressure adjustment. Major gene effects with polygenic components were the best-fitting model to explain the inheritance mode of LV mass. The estimated allele frequency of the gene was 0.089. CONCLUSION: There were significant familial correlations, heritability and a major gene effect on LV mass in the population-based families

Feasibility study of computed tomography colonography using limited bowel preparation at normal and low-dose levels study

The purpose was to evaluate low-dose CT colonography without cathartic cleansing in terms of image quality, polyp visualization and patient acceptance. Sixty-one patients scheduled for colonoscopy started a low-fiber diet, lactulose and amidotrizoic-acid for fecal tagging 2 days prior to the CT scan (standard dose, 5.8–8.2 mSv). The original raw data of 51 patients were modified and reconstructed at simulated 2.3 and 0.7 mSv levels. Two observers evaluated the standard dose scan regarding image quality and polyps. A third evaluated the presence of polyps at all three mSv levels in a blinded prospective way. All observers were blinded to the reference standard: colonoscopy. At three times patients were given questionnaires relating to their experiences and preference. Image quality was sufficient in all patients, but significantly lower in the cecum, sigmoid and rectum. The two observers correctly identified respectively 10/15 (67%) and 9/15 (60%) polyps ≥10 mm, with 5 and 8 false-positive lesions (standard dose scan). Dose reduction down to 0.7 mSv was not associated with significant changes in diagnostic value (polyps ≥10 mm). Eighty percent of patients preferred CT colonography and 13% preferred colonoscopy (P<0.001). CT colonography without cleansing is preferred to colonoscopy and shows sufficient image quality and moderate sensitivity, without impaired diagnostic value at dose-levels as low as 0.7 mSv

Isolation and Characterization of EstC, a New Cold-Active Esterase from Streptomyces coelicolor A3(2)

The genome sequence of Streptomyces coelicolor A3(2) contains more than 50 genes coding for putative lipolytic enzymes. Many studies have shown the capacity of this actinomycete to store important reserves of intracellular triacylglycerols in nutrient depletion situations. In the present study, we used genome mining of S. coelicolor to identify genes coding for putative, non-secreted esterases/lipases. Two genes were cloned and successfully overexpressed in E. coli as His-tagged fusion proteins. One of the recombinant enzymes, EstC, showed interesting cold-active esterase activity with a strong potential for the production of valuable esters. The purified enzyme displayed optimal activity at 35°C and was cold-active with retention of 25% relative activity at 10°C. Its optimal pH was 8.5–9 but the enzyme kept more than 75% of its maximal activity between pH 7.5 and 10. EstC also showed remarkable tolerance over a wide range of pH values, retaining almost full residual activity between pH 6–11. The enzyme was active toward short-chain p-nitrophenyl esters (C2–C12), displaying optimal activity with the valerate (C5) ester (kcat/Km = 737±77 s−1 mM−1). The enzyme was also very active toward short chain triglycerides such as triacetin (C2:0) and tributyrin (C4:0), in addition to showing good primary alcohol and organic solvent tolerance, suggesting it could function as an interesting candidate for organic synthesis of short-chain esters such as flavors

Looking to the future of zebrafish as a model to understand the genetic basis of eye disease

In this brief commentary, we provide some of our thoughts and opinions on the current and future use of zebrafish to model human eye disease, dissect pathological progression and advance in our understanding of the genetic bases of microphthalmia, andophthalmia and coloboma (MAC) in humans. We provide some background on eye formation in fish and conservation and divergence across vertebrates in this process, discuss different approaches for manipulating gene function and speculate on future research areas where we think research using fish may prove to be particularly effective