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991.
Kazuki Harada Manao Ozawa Kanako Ishihara Ryoji Koike Tetsuo Asai Hitoshi Ishikawa 《Microbiology and immunology》2009,53(2):107-111
Penner serotypes of C. jejuni in a total of 601 isolates from apparently healthy cattle, layer and broiler chickens in Japan were examined between 2001 and 2006. Predominant serotypes were B (O: 2, 19.1%), D (O: 4, 13.5%), Y (O: 37, 7.3%) and G (O: 8, 5.8%), whereas the remaining serotypes made up less than 5% of the total isolates. The frequency of ampicillin resistance in serotype G (65.6%) was significantly higher than in serotypes D (12.5%), B (11.2%), and Y (0%). Our results suggest that serotype is one factor contributing to the prevalence of ampicillin resistance in C. jejuni isolates. 相似文献
992.
993.
Characterization of the ABA-regulated global responses to dehydration in Arabidopsis by metabolomics 总被引:3,自引:0,他引:3
994.
995.
Shinya Nagashima Takeshi Hondo Hiroshi Nagata Takashi Ogiyama Jun Maeda Hiroaki Hoshii Toru Kontani Sadao Kuromitsu Keiko Ohga Masaya Orita Kazuki Ohno Ayako Moritomo Koichi Shiozuka Masako Furutani Makoto Takeuchi Mitsuaki Ohta Shin-ichi Tsukamoto 《Bioorganic & medicinal chemistry》2009,17(19):6926-6936
996.
Fumio Matsuda Yoko Shinbo Akira Oikawa Masami Yokota Hirai Oliver Fiehn Shigehiko Kanaya Kazuki Saito 《PloS one》2009,4(10)
Background
In metabolomics researches using mass spectrometry (MS), systematic searching of high-resolution mass data against compound databases is often the first step of metabolite annotation to determine elemental compositions possessing similar theoretical mass numbers. However, incorrect hits derived from errors in mass analyses will be included in the results of elemental composition searches. To assess the quality of peak annotation information, a novel methodology for false discovery rates (FDR) evaluation is presented in this study. Based on the FDR analyses, several aspects of an elemental composition search, including setting a threshold, estimating FDR, and the types of elemental composition databases most reliable for searching are discussed.Methodology/Principal Findings
The FDR can be determined from one measured value (i.e., the hit rate for search queries) and four parameters determined by Monte Carlo simulation. The results indicate that relatively high FDR values (30–50%) were obtained when searching time-of-flight (TOF)/MS data using the KNApSAcK and KEGG databases. In addition, searches against large all-in-one databases (e.g., PubChem) always produced unacceptable results (FDR >70%). The estimated FDRs suggest that the quality of search results can be improved not only by performing more accurate mass analysis but also by modifying the properties of the compound database. A theoretical analysis indicates that FDR could be improved by using compound database with smaller but higher completeness entries.Conclusions/Significance
High accuracy mass analysis, such as Fourier transform (FT)-MS, is needed for reliable annotation (FDR <10%). In addition, a small, customized compound database is preferable for high-quality annotation of metabolome data. 相似文献997.
998.
In vitro expansion of mouse primordial germ cell‐like cells recapitulates an epigenetic blank slate
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Hiroshi Ohta Kazuki Kurimoto Ikuhiro Okamoto Tomonori Nakamura Yukihiro Yabuta Hidetaka Miyauchi Takuya Yamamoto Yukiko Okuno Masatoshi Hagiwara Kenjiro Shirane Hiroyuki Sasaki Mitinori Saitou 《The EMBO journal》2017,36(13):1888-1907
The expansion of primordial germ cells (PGCs), the precursors for the oocytes and spermatozoa, is a key challenge in reproductive biology/medicine. Using a chemical screening exploiting PGC‐like cells (PGCLCs) induced from mouse embryonic stem cells (ESCs), we here identify key signaling pathways critical for PGCLC proliferation. We show that the combinatorial application of Forskolin and Rolipram, which stimulate cAMP signaling via different mechanisms, expands PGCLCs up to ~50‐fold in culture. The expanded PGCLCs maintain robust capacity for spermatogenesis, rescuing the fertility of infertile mice. Strikingly, during expansion, PGCLCs comprehensively erase their DNA methylome, including parental imprints, in a manner that precisely recapitulates genome‐wide DNA demethylation in gonadal germ cells, while essentially maintaining their identity as sexually uncommitted PGCs, apparently through appropriate histone modifications. By establishing a paradigm for PGCLC expansion, our system reconstitutes the epigenetic “blank slate” of the germ line, an immediate precursory state for sexually dimorphic differentiation. 相似文献
999.
Metabolic switching of astringent and beneficial triterpenoid saponins in soybean is achieved by a loss‐of‐function mutation in cytochrome P450 72A69
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Ryoichi Yano Kyoko Takagi Yoshitake Takada Kyosuke Mukaiyama Chigen Tsukamoto Takashi Sayama Akito Kaga Toyoaki Anai Satoru Sawai Kiyoshi Ohyama Kazuki Saito Masao Ishimoto 《The Plant journal : for cell and molecular biology》2017,89(3):527-539
Triterpenoid saponins are major components of secondary metabolites in soybean seeds and are divided into two groups: group A saponins, and 2,3‐dihydro‐2,5‐dihydroxy‐6‐methyl‐4H‐pyran‐4‐one (DDMP) saponins. The aglycone moiety of group A saponins consists of soyasapogenol A (SA), which is an oxidized β‐amyrin product, and the aglycone moiety of the DDMP saponins consists of soyasapogenol B (SB). Group A saponins produce a bitter and astringent aftertaste in soy products, whereas DDMP saponins have known health benefits for humans. We completed map‐based cloning and characterization of the gene Sg‐5, which is responsible for SA biosynthesis. The naturally occurring sg‐5 mutant lacks group A saponins and has a loss‐of‐function mutation (L164*) in Glyma15g39090, which encodes the cytochrome P450 enzyme, CYP72A69. An enzyme assay indicated the hydroxylase activity of recombinant CYP72A69 against SB, which also suggested the production of SA. Additionally, induced Glyma15g39090 mutants (R44* or S348P) lacked group A saponins similar to the sg‐5 mutant, indicating that Glyma15g39090 corresponds to Sg‐5. Endogenous levels of DDMP saponins were higher in the sg‐5 mutant than in the wild‐type lines due to the loss of the enzyme activity that converts SB to SA. Interestingly, the genomes of palaeopolyploid soybean and the closely related common bean carry multiple Sg‐5 paralogs in a genomic region syntenic to the soybean Sg‐5 region. However, SA did not accumulate in common bean samples, suggesting that Sg‐5 activity evolved after gene duplication event(s). Our results demonstrate that metabolic switching of undesirable saponins with beneficial saponins can be achieved in soybean by disabling Sg‐5. 相似文献
1000.
Toshiyuki Kohara Kazuki Nakayama Kazutoshi Watanabe Shin-ichi Kusaka Daiki Sakai Hiroshi Tanaka Kenji Fukunaga Shinji Sunada Mika Nabeno Ken-Ichi Saito Jun-ichi Eguchi Akiko Mori Shinji Tanaka Tomoko Bessho Keiko Takiguchi-Hayashi Takashi Horikawa 《Bioorganic & medicinal chemistry letters》2017,27(16):3733-3738
We herein describe the results of further evolution of glycogen synthase kinase (GSK)-3β inhibitors from our promising compounds containing a 3-methylmorpholine moiety. Transformation of the morpholine moiety into a piperazine moiety resulted in potent GSK-3β inhibitors. SAR studies focused on the nitrogen atom of the piperazine moiety revealed that a phenyl group afforded potent inhibitory activity toward GSK-3β. Docking studies indicated that the phenyl group on the piperazine nitrogen atom and the methyl group on the piperazine make cation-π and CH-π interactions with GSK-3β respectively. 4-Methoxyphenyl analogue 29 showed most potent inhibitory activity toward GSK-3β with good in vitro and in vivo pharmacokinetic profiles, and 29 demonstrated a significant decrease in tau phosphorylation after oral administration in mice. 相似文献