{"created":"2023-06-20T13:21:17.779285+00:00","id":1442,"links":{},"metadata":{"_buckets":{"deposit":"473aa852-3d2a-4785-bfdd-b33598c3666a"},"_deposit":{"created_by":21,"id":"1442","owners":[21],"pid":{"revision_id":0,"type":"depid","value":"1442"},"status":"published"},"_oai":{"id":"oai:ir.soken.ac.jp:00001442","sets":["2:430:20"]},"author_link":["0","0","0"],"item_1_creator_2":{"attribute_name":"著者名","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"上田, 弥生"}],"nameIdentifiers":[{}]}]},"item_1_creator_3":{"attribute_name":"フリガナ","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"ウエダ, ヤヨイ"}],"nameIdentifiers":[{}]}]},"item_1_date_granted_11":{"attribute_name":"学位授与年月日","attribute_value_mlt":[{"subitem_dategranted":"2009-03-24"}]},"item_1_degree_grantor_5":{"attribute_name":"学位授与機関","attribute_value_mlt":[{"subitem_degreegrantor":[{"subitem_degreegrantor_name":"総合研究大学院大学"}]}]},"item_1_degree_name_6":{"attribute_name":"学位名","attribute_value_mlt":[{"subitem_degreename":"博士（理学）"}]},"item_1_description_12":{"attribute_name":"要旨","attribute_value_mlt":[{"subitem_description":"　In flowering plants, after the transition from vegetative growth to reproductive development, primordial germ cell initials differentiate from somatic cells in flowers. Several genes that control the early stages of germ-cell development have been identified, however, little is known about the molecular mechanism determining the germ cell fate during sexual reproduction in plants. The <i>MEL1  (MEIOSIS ARRESIED ATLEPTOTENE1)</i> is the only plant ARGONAUTE (AGO) gene specifically expressing at the primordial germ cells. AGO proteins are known to be a key player in gene-silencing pathways guided by small RNAs. PlWl-domain containing subfamily has important roles in maintaining germ stem cells in animal. In plant, however, there is no <i>AGO</i> gene which belonging to PIWI subfamily. Therefore, a specific AGO gene system in plant germ cell development would be suggested.<br />　In this study, I focused on the characterization gene expressed at early stages of germ cells development specifically in relation to the MEL1 function. MEL1 is well-characterized ARGONAUTE family that has essential functions in germ cell development. To date the rice <i>MEL1</i> is the only gene available for investigating a genetic system conducting plant germ cell initiation and maintenance. A large portion of the genes identified specific in very early stages in germ cell development had unknown function However, comparison of gene expression profiles between wild-type and <i>mell-1</i> mutant down- or  up-regulated in<i>mell-1</i> mutant revealed many possible causal genes for <i>mell-1</i> dysfunction, i.e. most of which are not characterized previously. Of these genes, the <i>OsSPLl4</i>, one of<i> SQUAMOSA(SQUA)</i> promoter-binding-like(<i>SPL</i>) family genes, encoding a putative transcription factor, revealed to up-regulated in the <i>mell-l</i> mutant in both Affymetrix (Fold change=4.37) and Agilent (=3.01) microarray. Sequence and experimental analyses indicated that eleven <i>OsSPL</i> genes including <i>OsSPL14</i> were putative targets of <i>OsmiR156</i>, suggesting a possibility that the <i>OsSPL14</i> should be directly targeted by the rice MEL1 AGO with <i>miR156</i> microRNA as a guide molecule. Moreover, the volume of <i>miR156</i> RNA detected in the co-IP fraction with the anti-MEL1antibody 3.2-fold more than in that with the pre-immune serum. The detection level of <i>miRl56</i> depended on that of the MEL1 protein, as the <i>miR156</i> co-IP with the MEL1 immune complex protein, but few or not with precipitates recovered using <i>mell-1</i> mutant or preimmune serum. These data strongly suggest that the MEL1forms a complex with the <i>miR156</i> microRNA <i>in vivo</i>. These results strongly suggested that the <i>miR156</i>microRNA was one of good candidates of guide RNA molecules of the MEL1 AGO.<br />　Analysis performed in each section and results obtained from the  analysis are summarized as follows.<br />　In the Section 1, the whole transcriptome profiles of plant reproductive process, including early stages that are difficult to be dissected in <i>Arabidopsis</i>, was obtained by using the Affymetrix rice genome array analysis and provided as a dataset of rice reproductive expression atlas. In addition, using the atlas data, the gene expression patterns of several genes that the are highly expressed in early development stage were investigated. A large part of genes that are expressed in early reproductive development remains uncharacterized because most of pre-meiotic stage specific genes were not categorized to any functions by GO analysis. However, the expression patterns of other meiosis-related genes were well corresponded previous reports. The specific genes that were found in this study may have the crucial function at early germ cells development stages.<br />　In the section 2, to confirm the spatial and temporal expression of the <i>MEL1</i> gene, mRNA <i>in situ</i> hybridization was performed on the anther sections with the <i>MSP1</i> gene as cellular marker of young anther tissues. Expression of the <i>MEL1</i> was earlier than that of the <i>MSP1</i>, which clearly indicates that the <i>MEL1</i>mRNA expression start at the archesporial initials. The <i>MEL1</i> expression is not required for the germ-cell initiation, but for the maintenance of germ cells. In the Section 2, <i>in situ</i> hybridization of the <i>OsNOZZLE(OsNZZ)</i>, a putative rice ortholog of <i>Arabidopsis</i> <i>SPOLOCYTELESS|NOZZLE</i> was also performed.  Different from the <i>MEL1</i> and the, <i>MSP1</i>,the <i>OsNZZ</i> mRNA was expressed both in developing anther wall layers and sporogenous cells similar that of <i>Arabidopsis</i> <i>SPL/NZZ</i>, but it was not detected in archesporial cells. Although their function is not the same as <i>Arabidopsis</i> SPL/NZZ, OsNZZ</i> may have function in early germ cell development.<br />　In the Section 3, the microarray at 1-cm young panicle, several genes responsive for environmental stresses and/or hormone-responsive genes up-regulated. It suggests that absence of the MEL1 may cause stressful condition, thus many stress-response genes and ethylene signaling-related gene are induced. TheMEL1 may inhibits stress responses in germ cells to accomplish precise germ cell division and meiosis. In addition, some transposable element-like transcripts were also up-regulated in <i>mel-1</i> mutant. It was demonstrated that <i>Drosophila piwi </i> mutations impact retrotransposon mobility. MEL1 may also suppress the activity of transposable elements during rice germ-cell development. On the other hand, many genes related to cell structure and cycle were down-regulated in the <i>mell-1</i> mutant. These results may indicated that in<i>mell-1</i> mutant, the failure of pre-meiotic mitosis of sporogenous cells in the <i>mell-1</i> mutant anther (Nonomura et al. 2007) was caused by down-regulation of these genes. At pre-meiotic S/G2 stage of young anthers, few genes were affected by the <i>mell-1</i> mutation. Most of up- and down-regulation of genes in the later stages of pre-meiotic germ-cell development might be secondary effects of <i>mell-1</i> mutation.<br />　Finally, the Section 4 suggested a possibility that the rice MEL1 AGO directly regulated the <i>OsSPL14</i>gene with the plant specific microRNA, <i>miR156</i> as described above.<br /><br />　Results obtained in this thesis will provide new and useful information to understand the gene functions in initiation of germ cells development and maintenance of germ cell identity in rice.","subitem_description_type":"Other"}]},"item_1_description_18":{"attribute_name":"フォーマット","attribute_value_mlt":[{"subitem_description":"application/pdf","subitem_description_type":"Other"}]},"item_1_description_7":{"attribute_name":"学位記番号","attribute_value_mlt":[{"subitem_description":"総研大甲第1249号","subitem_description_type":"Other"}]},"item_1_select_14":{"attribute_name":"所蔵","attribute_value_mlt":[{"subitem_select_item":"有"}]},"item_1_select_8":{"attribute_name":"研究科","attribute_value_mlt":[{"subitem_select_item":"生命科学研究科"}]},"item_1_select_9":{"attribute_name":"専攻","attribute_value_mlt":[{"subitem_select_item":"18 遺伝学専攻"}]},"item_1_text_10":{"attribute_name":"学位授与年度","attribute_value_mlt":[{"subitem_text_value":"2008"}]},"item_creator":{"attribute_name":"著者","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"UEDA, Yayoi","creatorNameLang":"en"}],"nameIdentifiers":[{}]}]},"item_files":{"attribute_name":"ファイル情報","attribute_type":"file","attribute_value_mlt":[{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2016-02-17"}],"displaytype":"simple","filename":"甲1249_要旨.pdf","filesize":[{"value":"305.9 kB"}],"format":"application/pdf","licensetype":"license_11","mimetype":"application/pdf","url":{"label":"要旨・審査要旨","url":"https://ir.soken.ac.jp/record/1442/files/甲1249_要旨.pdf"},"version_id":"c646c88b-853e-41c7-903b-e204830f0f74"},{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2016-02-17"}],"displaytype":"simple","filename":"甲1249_本文.pdf","filesize":[{"value":"13.9 MB"}],"format":"application/pdf","licensetype":"license_11","mimetype":"application/pdf","url":{"label":"本文","url":"https://ir.soken.ac.jp/record/1442/files/甲1249_本文.pdf"},"version_id":"e5e9abac-941c-4842-9390-3b7a7cbc607a"}]},"item_language":{"attribute_name":"言語","attribute_value_mlt":[{"subitem_language":"eng"}]},"item_resource_type":{"attribute_name":"資源タイプ","attribute_value_mlt":[{"resourcetype":"thesis","resourceuri":"http://purl.org/coar/resource_type/c_46ec"}]},"item_title":"Molecular characterization of genes essential for early development of germ cells in rice","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"Molecular characterization of genes essential for early development of germ cells in rice"},{"subitem_title":"Molecular characterization of genes essential for early development of germ cells in rice","subitem_title_language":"en"}]},"item_type_id":"1","owner":"21","path":["20"],"pubdate":{"attribute_name":"公開日","attribute_value":"2010-03-24"},"publish_date":"2010-03-24","publish_status":"0","recid":"1442","relation_version_is_last":true,"title":["Molecular characterization of genes essential for early development of germ cells in rice"],"weko_creator_id":"21","weko_shared_id":-1},"updated":"2023-06-20T16:03:27.272963+00:00"}