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Arabidopsis is well-known to the world's plant research community as a model plant. Many significant resources and innovative research tools, as well as large bodies of genomic information, have been created and shared by the research community, partly explaining why so many researchers use this small plant for their research. The genome sequence of Arabidopsis was fully characterized by the end of the 20th century. Soon afterwards, the Arabidopsis research community began a 10-year international project on the functional genomics of the species. In 2001, at the beginning of the project, the RIKEN BioResource Center (BRC) started its Arabidopsis resource project. The following year, the National BioResource Project was launched, funded by the Japanese government, and the RIKEN BRC was chosen as a core facility for Arabidopsis resource. Seeds of RIKEN Arabidopsis transposon-tagged mutant lines, activation-tagged lines, full-length cDNA over-expresser lines, and natural accessions, as well as RIKEN Arabidopsis full-length cDNA clones and T87 cells, are preserved at RIKEN BRC and distributed around the world. The major resources provided to the research community have been full-length cDNA clones and insertion mutants that are suitable for use in reverse-genetics studies. This paper provides an overview of the Arabidopsis resources made available by RIKEN BRC and examples of research that has been done by users and developers of these resources. [ABSTRACT FROM AUTHOR]

Populations of arctic alpine plants likely disappeared and re-colonised several times at the southern edge of their distributions during glacial and interglacial cycles throughout the Quaternary. Range shift and population fragmentation after a glacial period would affect the genetic structure of such plants in southernmost populations. We aimed to elucidate how climatic oscillations influenced the population subsistence of alpine plants in the Japanese Archipelago as one of the southernmost populations, by inferring the genetic structure of Arabidopsis kamchatica subsp. kamchatica and the intraspecific littoral taxon, subsp. kawasakiana. We identified genotypes based on the haplotypes of five nuclear genes and two chloroplast DNA spacers for 164 individuals from 24 populations. Most populations harboured only one private genotype, whereas few polymorphisms were found in each population. Two genetic genealogies were found, suggesting that northern Japanese populations of alpine subsp. kamchatica, subsp. kawasakiana and the northerly subsp. kamchatica in eastern Russia and Alaska clustered and differentiated from populations in central Honshu, western Japan and Taiwan. During climatic oscillations, the genetic structure of extant southernmost populations would have been shaped by strong genetic drift under population fragmentation and randomly fixed to a single genotype among their ancestral polymorphisms. [ABSTRACT FROM AUTHOR]

Some studies for radiological protection of the environment have been made at the National Institute of Radiological Sciences (NIRS). Transfer of radionuclides and related elements has been investigated for dose estimation of non-human biota. A parameter database and radionuclide transfer models have been also developed for the Japanese environments. Dose (rate)–effect relationships for survival, growth and reproduction have been investigated in conifers, Arabidopsis, fungi, earthworms, springtails, algae, duckweeds, daphnia and medaka. Also genome-wide gene expression analysis has been carried out by high coverage expression profiling (HiCEP). Effects on aquatic microbial communities have been studied in experimental ecosystem models, i.e., microcosms. Some effects were detected at a dose rate of 1 Gy day−1 and were likely to arise from interspecies interactions. The results obtained at NIRS have been used in development of frameworks for environmental protection by some international bodies, and will contribute to environmental protection in Japan and other Asian countries. [ABSTRACT FROM PUBLISHER]

Gentians are herbaceous perennials blooming in summer through autumn. Although they are popular ornamental flowers in Japan, the regulation of their timing of flowering has not been studied. We identified and characterized gentian orthologs of the Arabidopsis FT/TFL1 gene family to elucidate the mechanisms of flowering initiation. We isolated three gentian orthologs of FT and TFL1, denoted GtFT1, GtFT2 and GtTFL1. Since up-regulation of GtFT1 and GtFT2 as well as down-regulation of GtTFL1 promoted floral initiation in gentian plantlets, these genes affected floral initiation in a similar way to Arabidopsis FT and TFL1. The expression levels of GtFT1 and GtFT2 in leaves of late-flowering gentian increased prior to floral initiation, whereas GtTFL1 was highly expressed in shoot apical meristem at the vegetative stage and decreased drastically just before flowering initiation. Comparison of gene expression patterns showed that GtFT1 expression increased earlier in early-flowering than in late-flowering gentian, whereas the timing of the increase in GtFT2 expression was similar in early- and late-flowering plants. The GtTFL1 expression in early-flowering gentian was extremely low throughout the vegetative and reproductive stages. These results indicated that either the up-regulation of GtFT1 or the down-regulation of GtTFL1 may determine flowering time. Furthermore, we found that early-flowering but not late-flowering gentians have a 320 bp insertion in the promoter region of GtTFL1. Thus, the negligible expression of GtTFL1 in early-flowering lines may be due to this insertion, resulting in a shortened vegetative stage. [ABSTRACT FROM PUBLISHER]

The events occurring at the onset of meiosis have not been fully elucidated. In the present study, OsAM1 was identified in rice (Oryza sativa L.) by map-based cloning. OsAM1, a homolog of Arabidopsis SWI1 and maize AM1, encodes a protein with a coiled-coil domain in its central region. In the Osam1 mutant, pollen mother cells are arrested at leptotene, showing that OsAM1 is required for the leptotene-zygotene transition. Immunocytological analysis revealed that OsAM1 exists as foci in early prophase I meiocytes. Very faint OsREC8 foci persisted in the Osam1 mutant, indicating that OsAM1 is not required for the initial meiotic recruitment of OsREC8. In the absence of OsAM1, many other critical meiotic components, including PAIR2, ZEP1 and OsMER3, could not be correctly installed onto chromosomes. In contrast, in pair2, Osmer3 and zep1 mutants, OsAM1 could be loaded normally, suggesting that OsAM1 plays a fundamental role in building the proper chromosome structure at the beginning of meiosis. [ABSTRACT FROM AUTHOR]

Presents abstracts of studies on metabolism and metabolite accumulation of plants, presented at the 68th Annual Meeting of the Botanical Society of Japan held at the Shonan Campus of Nihon University in Japan from September 9 to 12, 2004. "A Novel Protease Involved in Phenylpropanoid Metabolism," by Atsushi Minami, Shinichi Sugihara et al.; "Flavonoids in Centaurea Ruthenica As Yellow Flower Pigments," by Tamaki Mishio and Tsukasa Iwashina; "Regulation of the Blosynthesis of Isoprene Units in Arabidopsis," by Doris Albinsky, Hiroyuki Kasahara et al.

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