出芽酵母におけるSec23ホモログNel1の機能解析

学位の種別: 課程博士審査委員会委員 : (主査)東京大学准教授 佐藤 健, 東京大学教授 中野 明彦, 東京大学准教授 上田 貴志, 東京大学准教授 坪井 貴司, 東京大学教授 和田 元University of Tokyo(東京大学

KATANIN-dependent mechanical properties of the stigmatic cell wall mediate the pollen tube path in Arabidopsis.

Successful fertilization in angiosperms depends on the proper trajectory of pollen tubes through the pistil tissues to reach the ovules. Pollen tubes first grow within the cell wall of the papilla cells, applying pressure to the cell. Mechanical forces are known to play a major role in plant cell shape by controlling the orientation of cortical microtubules (CMTs), which in turn mediate deposition of cellulose microfibrils (CMFs). Here, by combining imaging, genetic and chemical approaches, we show that isotropic reorientation of CMTs and CMFs in aged Col-0 and katanin1-5 (ktn1-5) papilla cells is accompanied by a tendency of pollen tubes to coil around the papillae. We show that this coiled phenotype is associated with specific mechanical properties of the cell walls that provide less resistance to pollen tube growth. Our results reveal an unexpected role for KTN1 in pollen tube guidance on the stigma by ensuring mechanical anisotropy of the papilla cell wall

A functional polymorphism in the epidermal growth factor gene predicts hepatocellular carcinoma risk in Japanese hepatitis C patients

Background: A single nucleotide polymorphism (SNP) in the epidermal growth factor (EGF) gene (rs4444903) has been associated with increased risk of cancer, including hepatocellular carcinoma (HCC). The aim of this study was to examine the relationship between the EGF SNP genotype and the development and prognosis of HCC, in a Japanese population. Methods: Restriction fragment-length polymorphism was used to determine the presence of the EGF SNP genotype in 498 patients, including 208 patients with HCC. The level of EGF messenger ribonucleic acid (mRNA) expression in cancerous tissues was measured by quantitative reverse transcription polymerase chain reaction. The correlation between the EGF SNP genotype and prognosis was statistically analyzed in the patients with HCC. Results: The proportion of the A/A, A/G, and G/G genotypes were 5.3%, 42.8%, and 51.9%, respectively, in the patients with HCC, whereas in those without HCC, they were 8.6%, 35.9%, and 55.5%, respectively, revealing that the odds ratio (OR) of developing HCC was higher in patients with a G allele (OR =1.94, P=0.080 for A/G patients and OR =1.52, P=0.261 for G/G patients, as compared with A/A patients). In particular, when the analysis was limited to the 363 patients with hepatitis C, the OR for developing HCC was 3.54 (P=0.014) for A/G patients and was 2.85 (P=0.042) for G/G patients, as compared with A/A patients. Tumoral EGF mRNA expression in G/G patients was significantly higher than that in A/A patients (P=0.033). No statistically significant differences were observed between the EGF SNP genotype and diseasefree or overall survival. Conclusion: The EGF SNP genotype might be associated with a risk for the development of HCC in Japanese patients but not with prognosis. Of note, the association is significantly stronger in patients with hepatitis C, which is the main risk factor for HCC in Japan

"Erwachsenenbildung bisher nur gedanklich verankert": Ergebnisse einer Befragung von Weiterbildungsverbänden zum DQR

Abstract Background Molecular biomarkers capable of predicting recurrence patterns and prognosis are helpful for risk stratification and providing appropriate treatment to patients with hepatocellular carcinoma (HCC). In this study, we focused on G protein-coupled receptor 155 (GPR155), a cell surface signaling protein, as a candidate biomarker. Methods We analyzed GPR155 expression, DNA methylation, and copy number in HCC cell lines. The clinical significance of GPR155 expression was evaluated using 144 pairs of surgically resected liver and normal tissues with subgroup analysis based on hepatitis virus infection. Results GPR155 mRNA expression levels were differential and were decreased in 89% of HCC cell lines. No DNA methylation was detected, whereas copy number alterations were present in five (56%) HCC cell lines. GPR155 mRNA expression level was independent of background liver status and significantly lower in HCC tissues than corresponding normal liver tissues. The expression patterns of GPR155 protein by immunohistochemical staining were significantly associated with those of GPR155 mRNA. Downregulation of GPR155 was significantly associated with more aggressive HCC phenotypes including high preoperative α-fetoprotein, poor differentiation, serosal infiltration, vascular invasion, and advanced disease stage. Patients with downregulation of GPR155 were more likely to have worse prognosis after curative resection irrespective of hepatitis virus infection. Patients who experienced extrahepatic (distant) recurrences had significantly lower GPR155 expression than those with intrahepatic (liver confined) recurrences. Conclusions Downregulation of GPR155 may serve as a prognosticator that also predicts initial recurrence sites independent of hepatitis virus infection

Actors of ROS Homeostasis in Stigmatic Cells Essential for Plant Reproduction

International audienceReactive oxygen species (ROS) play important roles during development and responses to external stimuli. In Brassicaceae, the stigma epidermis accumulates a large amount of ROS. Moreover, regulating the stigmatic ROS status is crucial for Self-incompatibility (SI) mechanisms, to ensure self-pollen rejection while promoting compatible pollen. Here, scanning our transcriptomic data in light of recent advances in the Brassicaceae SI system, we identified Class III peroxidases that are highly expressed in mature stigma and might regulate stigma ROS homeostasis. We also found two Receptor Like Kinases from the CYSTEINE-RICH RECEPTOR-LIKE KINASES family (CRK31 and CRK41) strongly upregulated upon incompatible pollination. We proposed that these two CRKs might be part of the ROS-mediated SI response and serve to connect pollen recognition and ROS accumulation

Actors of ROS Homeostasis in Stigmatic Cells Essential for Plant Reproduction

International audienceReactive oxygen species (ROS) play important roles during development and responses to external stimuli. In Brassicaceae, the stigma epidermis accumulates a large amount of ROS. Moreover, regulating the stigmatic ROS status is crucial for Self-incompatibility (SI) mechanisms, to ensure self-pollen rejection while promoting compatible pollen. Here, scanning our transcriptomic data in light of recent advances in the Brassicaceae SI system, we identified Class III peroxidases that are highly expressed in mature stigma and might regulate stigma ROS homeostasis. We also found two Receptor Like Kinases from the CYSTEINE-RICH RECEPTOR-LIKE KINASES family (CRK31 and CRK41) strongly upregulated upon incompatible pollination. We proposed that these two CRKs might be part of the ROS-mediated SI response and serve to connect pollen recognition and ROS accumulation

Rapid detection of rifampicin-resistant Mycobacterium tuberculosis, based on isothermal DNA amplification and DNA chromatography

Rapid and easy detection of nucleotide point mutations in bacterial pathogens associated with drug resistance is essential for the proper use of antimicrobials. Here, we developed a rapid and simple method for the detection of mutations using Loop-mediated isothermal amplification (LAMP) combined with the single-tag hybridization (STH) chromatographic printed array strips (PAS) method. This procedure is able to detect four mutations (C1349 T, A1295C, G1303 T, A1304 T) in Rifampicin Resistance Determining Region (RRDR) of rifampicin-resistant Mycobacterium tuberculosis (RR-TB), simultaneously. LAMP reactions contained a LAMP primer and eight allele-specific primers for each mutation. The allele-specific primers products were detected by nucleic acid chromatography using PAS. Four detection lines were detected there, one of which was detected at different positions depend on the wild type and the mutant type. We carried out the four mutations detection using 31 genomic DNA (2 A1295T, 1 G1303 T, 6 A1304 T, 22 C1349 T) from clinical isolate. The mutations have been confirmed by sequence analysis. The detection results were completely consistent with the sequence analysis. In the present study, four mutations could be detected, but only 60% of RR-TB could be detected with these four. It is expected that the detection rate will increase by adding more mutant primers. The combined LAMP and STH chromatographic PAS method is a simple and rapid method for detecting point mutations in clinical isolates as a point-of-care testing (POCT) technique. In addition, it does not require special equipment and can meet the demand in areas where drug-resistant bacteria are endemic, such as developing countries