アサガオ芽生の日長反応

京都大学0048新制・課程博士農学博士農博第40号新制||農||19(附属図書館)学位論文||S38||N39(農学部図書室)407京都大学大学院農学研究科農林生物学専攻(主査)教授 今村 駿一郎, 教授 塚本 洋太郎, 教授 葛西 善三郎学位規則第5条第1項該当Kyoto UniversityDA

H2A.Bbd: an X-chromosome-encoded histone involved in mammalian spermiogenesis

Despite the identification of H2A.Bbd as a new vertebrate-specific replacement histone variant several years ago, and despite the many in vitro structural characterizations using reconstituted chromatin complexes consisting of this variant, the existence of H2A.Bbd in the cell and its location has remained elusive. Here, we report that the native form of this variant is present in highly advanced spermiogenic fractions of mammalian testis at the time when histones are highly acetylated and being replaced by protamines. It is also present in the nucleosomal chromatin fraction of mature human sperm. The ectopically expressed non-tagged version of the protein is associated with micrococcal nuclease-refractory insoluble fractions of chromatin and in mouse (20T1/2) cell line, H2A.Bbd is enriched at the periphery of chromocenters. The exceedingly rapid evolution of this unique X-chromosome-linked histone variant is shared with other reproductive proteins including those associated with chromatin in the mature sperm (protamines) of many vertebrates. This common rate of evolution provides further support for the functional and structural involvement of this protein in male gametogenesis in mammals

Distribution of the globin gene in active and inactive chromatin fractions from friend erythroleukemia cells

Stimulation of the T3C12 clone of Friend erythroleukemia cells with 1.2% dimethyl sulfoxide (DMSO) results in progressive increase in the concentration of globin mRNA sequences in the total cellular RNA of treated cells, as measured by nucleic acid hybridization employing a globin cDNA probe. The greatest increment in the content of globin RNA occurs between 30 and 40 h after addition of DMSO. Globin cDNA was also used to measure the concentration of globin-specific sequences in the DNA and RNA of transcriptionally active and inactive chromatin fractions prepared from these cells by the DNase II-MgCl2 procedure of Gottesfeld et al. [16]. Essentially equal concentrations of globin sequences are present in the DNA isolated from active and inactive chromatin fractions of cells grown in the presence of 1.2% DMSO for 50 h (the time of initiation of hemoglobin synthesis). Furthermore, there are no significant differences in the globin gene concentrations between the active chromatin fractions from DMSO-treated and control cultures at either 50 or 120 h after initiation of DMSO treatment. However, chromatin-associated RNA isolated from the active chromatin of cells synthesizing maximum amounts of hemoglobin (120 h) contains a higher concentration of globin sequences than RNA from the active chromatin of control cells. Chromatin fractions from untreated cells also contain a significant amount of RNA which hybridizes to the globin cDNA probe. These observations suggest that both transcriptional and post-transcriptional control mechanisms are involved in hemoglobin gene expression in T3C12 erythroleukemia cells.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22672/1/0000225.pd

The Polycomb Protein and E3 Ubiquitin Ligase Ring1B Harbors an IRES in its Highly Conserved 5′ UTR

Ring1B is an essential member of the highly conserved Polycomb group proteins, which orchestrate developmental processes, cell growth and stem cell fate by modifying local chromatin structure. Ring1B was found to be the E3 ligase that monoubiquitinates histone H2A, which adds a new level of chromatin modification to Polycomb group proteins. Here we report that Ring1B belongs to the exclusive group of proteins that for their translation depend on a stable 5′ UTR sequence in their mRNA known as an Internal Ribosome Entry Site (IRES). In cell transfection assays the Ring1B IRES confers significantly higher expression levels of Ring1B than a Ring1B cDNA without the IRES. Also, dual luciferase assays show strong activity of the Ring1B IRES. Although our findings indicate Ring1B can be translated under conditions where cap-dependent translation is impaired, we found the Ring1B IRES to be cap-dependent. This raises the possibility that translational control of Ring1B is a multi-layered process and that translation of Ring1B needs to be maintained under varying conditions, which is in line with its essential role as an E3 ligase for monoubiquitination of histone H2A in the PRC1 Polycomb protein complex

Differential gene expression profiles of gastric cancer cells established from primary tumour and malignant ascites

Advanced gastric cancer is often accompanied by metastasis to the peritoneum, resulting in a high mortality rate. Mechanisms involved in gastric cancer metastasis have not been fully clarified because metastasis involves multiple steps and requires a combination of altered expressions of many different genes. Thus, independent analysis of any single gene would be insufficient to understand all of the aspects of gastric cancer peritoneal dissemination. In this study, we performed a global analysis of the differential gene expression of a gastric cancer cell line established from a primary main tumour (SNU-1) and of other cell lines established from the metastasis to the peritoneal cavity (SNU-5, SNU-16, SNU-620, KATO-III and GT3TKB). The application of a high-density cDNA microarray method made it possible to analyse the expression of approximately 21 168 genes. Our examinations of SNU-5, SNU-16, SNU-620, KATO-III and GT3TKB showed that 24 genes were up-regulated and 17 genes down-regulated besides expression sequence tags. The analysis revealed the following altered expression such as: (a) up-regulation of CD44 (cell adhesion), keratins 7, 8, and 14 (epitherial marker), aldehyde dehydrogenase (drug metabolism), CD9 and IP3 receptor type3 (signal transduction); (b) down-regulation of IL2 receptor γ, IL4-Stat (immune response), p27 (cell cycle) and integrin β4 (adhesion) in gastric cancer cells from malignant ascites. We then analysed eight gastric cancer cell lines with Northern blot and observed preferential up-regulation and down-regulation of these selected genes in cells prone to peritoneal dissemination. Reverse transcriptase–polymerase chain reaction confirmed that several genes selected by DNA microarray were also overexpressed in clinical samples of malignant ascites. It is therefore considered that these genes may be related to the peritoneal dissemination of gastric cancers. The results of this global gene expression analysis of gastric cancer cells with peritoneal dissemination, promise to provide a new insight into the study of human gastric cancer peritoneal dissemination

アサガオの茎と花の生長点の発達過程

京都大学0048新制・課程博士農学博士農博第49号新制||農||34(附属図書館)学位論文||S39||N90(農学部図書室)853京都大学大学院農学研究科農林生物学専攻(主査)教授 今村 駿一郎, 教授 西山 市三, 教授 塚本 洋太郎学位規則第5条第1項該当Kyoto UniversityDA