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  • 1
    Publication Date: 2008-04-12
    Description: RNA interference (RNAi) is a mechanism by which double-stranded RNAs (dsRNAs) suppress specific transcripts in a sequence-dependent manner. dsRNAs are processed by Dicer to 21-24-nucleotide small interfering RNAs (siRNAs) and then incorporated into the argonaute (Ago) proteins. Gene regulation by endogenous siRNAs has been observed only in organisms possessing RNA-dependent RNA polymerase (RdRP). In mammals, where no RdRP activity has been found, biogenesis and function of endogenous siRNAs remain largely unknown. Here we show, using mouse oocytes, that endogenous siRNAs are derived from naturally occurring dsRNAs and have roles in the regulation of gene expression. By means of deep sequencing, we identify a large number of both approximately 25-27-nucleotide Piwi-interacting RNAs (piRNAs) and approximately 21-nucleotide siRNAs corresponding to messenger RNAs or retrotransposons in growing oocytes. piRNAs are bound to Mili and have a role in the regulation of retrotransposons. siRNAs are exclusively mapped to retrotransposons or other genomic regions that produce transcripts capable of forming dsRNA structures. Inverted repeat structures, bidirectional transcription and antisense transcripts from various loci are sources of the dsRNAs. Some precursor transcripts of siRNAs are derived from expressed pseudogenes, indicating that one role of pseudogenes is to adjust the level of the founding source mRNA through RNAi. Loss of Dicer or Ago2 results in decreased levels of siRNAs and increased levels of retrotransposon and protein-coding transcripts complementary to the siRNAs. Thus, the RNAi pathway regulates both protein-coding transcripts and retrotransposons in mouse oocytes. Our results reveal a role for endogenous siRNAs in mammalian oocytes and show that organisms lacking RdRP activity can produce functional endogenous siRNAs from naturally occurring dsRNAs.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Watanabe, Toshiaki -- Totoki, Yasushi -- Toyoda, Atsushi -- Kaneda, Masahiro -- Kuramochi-Miyagawa, Satomi -- Obata, Yayoi -- Chiba, Hatsune -- Kohara, Yuji -- Kono, Tomohiro -- Nakano, Toru -- Surani, M Azim -- Sakaki, Yoshiyuki -- Sasaki, Hiroyuki -- England -- Nature. 2008 May 22;453(7194):539-43. doi: 10.1038/nature06908. Epub 2008 Apr 10.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Human Genetics, Department of Integrated Genetics, National Institute of Genetics, Research Organization of Information and Systems, Mishima 411-8540, Japan. toshwata@lab.nig.ac.jp〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18404146" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Argonaute Proteins ; Eukaryotic Initiation Factor-2/deficiency/genetics/metabolism ; Female ; Gene Expression Regulation, Developmental ; Gene Library ; Mice ; Mice, Inbred C57BL ; Molecular Sequence Data ; Oocytes/growth & development/*metabolism ; Polymerase Chain Reaction ; Pseudogenes/genetics ; *RNA Interference ; RNA, Double-Stranded/*genetics/*metabolism ; RNA, Messenger/*genetics/metabolism ; RNA, Small Interfering/*genetics/*metabolism ; Retroelements/genetics ; Ribonuclease III/deficiency/genetics/metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2008-06-20
    Description: Lancelets ('amphioxus') are the modern survivors of an ancient chordate lineage, with a fossil record dating back to the Cambrian period. Here we describe the structure and gene content of the highly polymorphic approximately 520-megabase genome of the Florida lancelet Branchiostoma floridae, and analyse it in the context of chordate evolution. Whole-genome comparisons illuminate the murky relationships among the three chordate groups (tunicates, lancelets and vertebrates), and allow not only reconstruction of the gene complement of the last common chordate ancestor but also partial reconstruction of its genomic organization, as well as a description of two genome-wide duplications and subsequent reorganizations in the vertebrate lineage. These genome-scale events shaped the vertebrate genome and provided additional genetic variation for exploitation during vertebrate evolution.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Putnam, Nicholas H -- Butts, Thomas -- Ferrier, David E K -- Furlong, Rebecca F -- Hellsten, Uffe -- Kawashima, Takeshi -- Robinson-Rechavi, Marc -- Shoguchi, Eiichi -- Terry, Astrid -- Yu, Jr-Kai -- Benito-Gutierrez, E Lia -- Dubchak, Inna -- Garcia-Fernandez, Jordi -- Gibson-Brown, Jeremy J -- Grigoriev, Igor V -- Horton, Amy C -- de Jong, Pieter J -- Jurka, Jerzy -- Kapitonov, Vladimir V -- Kohara, Yuji -- Kuroki, Yoko -- Lindquist, Erika -- Lucas, Susan -- Osoegawa, Kazutoyo -- Pennacchio, Len A -- Salamov, Asaf A -- Satou, Yutaka -- Sauka-Spengler, Tatjana -- Schmutz, Jeremy -- Shin-I, Tadasu -- Toyoda, Atsushi -- Bronner-Fraser, Marianne -- Fujiyama, Asao -- Holland, Linda Z -- Holland, Peter W H -- Satoh, Nori -- Rokhsar, Daniel S -- BBS/B/12067/Biotechnology and Biological Sciences Research Council/United Kingdom -- BBS/B/12067/2/Biotechnology and Biological Sciences Research Council/United Kingdom -- Biotechnology and Biological Sciences Research Council/United Kingdom -- Wellcome Trust/United Kingdom -- England -- Nature. 2008 Jun 19;453(7198):1064-71. doi: 10.1038/nature06967.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Energy Joint Genome Institute, Walnut Creek, California 94598, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18563158" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Chordata/classification/*genetics ; Conserved Sequence ; DNA Transposable Elements/genetics ; *Evolution, Molecular ; Gene Duplication ; Genes/genetics ; Genetic Linkage ; Genome/*genetics ; Humans ; Introns/genetics ; Karyotyping ; Multigene Family ; Phylogeny ; Polymorphism, Genetic/genetics ; Proteins/genetics ; Synteny ; Time Factors ; Vertebrates/classification/genetics
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 2016-03-22
    Description: We developed a resistive-pulse sensor with a solid-state pore and measured the latex agglutination of submicron particles induced by antigen-antibody interaction for single-molecule detection of proteins. We fabricated the pore based on numerical simulation to clearly distinguish between monomer and dimer latex particles. By measuring single dimers agglutinated in the single-molecule regime, we detected single human alpha-fetoprotein molecules. Adjusting the initial particle concentration improves the limit of detection (LOD) to 95 fmol/l. We established a theoretical model of the LOD by combining the reaction kinetics and the counting statistics to explain the effect of initial particle concentration on the LOD. The theoretical model shows how to improve the LOD quantitatively. The single-molecule detection studied here indicates the feasibility of implementing a highly sensitive immunoassay by a simple measurement method using resistive-pulse sensing.
    Print ISSN: 0003-6951
    Electronic ISSN: 1077-3118
    Topics: Physics
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 7127-7129 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Polycrystalline iron oxide films, 0.1–1.1 μm in thickness, are synthesized on glass substrates at room temperature directly from an aqueous solution of FeCl2 by ferrite plating. The films have a single phase spinel structure of mixed solution (Fe3O4)1−x–(γ-Fe2O3)x, as revealed by x-ray diffractometer and conversion electron 57Fe Mössbauer spectroscopy. At room temperature the films exhibit negative magnetoresistance (MR) of ratio ΔR/R=−3.3% to −7.4%, which is ascribed to intergranular tunneling of spin polarized electrons of Fe3O4. The resistivity R of the films is 2.2×100–1.3×103 Ω cm, much higher than that (∼10−2 Ω cm) reported for bulk samples of Fe3O4; R and ΔR/R depend on the plating conditions and, therefore, the composition x in (Fe3O4)1−x–(γ-Fe2O3)x of the samples. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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