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Structure of lampbrush chromosome loops during different states of transcriptional activity as visualized in the presence of physiological salt concentrations

Please always quote using this URN: urn:nbn:de:bvb:20-opus-39304
  • Lampbrush chromosomes of amphibian oocytes were isolated in the presence of near-physiological salt concentrations, to preserve their native state, and studied by electron microscopy of ultrathin s~dions. The transcriptional state of the lampbrush chromosomes was experimentally modulated by incubating the oocytes for various time periods in medium containing actinomycin D. The observations show that the structure of the lateral loops changes rapidly in response to alterations in transcriptional activity. During decreasing transcriptionalLampbrush chromosomes of amphibian oocytes were isolated in the presence of near-physiological salt concentrations, to preserve their native state, and studied by electron microscopy of ultrathin s~dions. The transcriptional state of the lampbrush chromosomes was experimentally modulated by incubating the oocytes for various time periods in medium containing actinomycin D. The observations show that the structure of the lateral loops changes rapidly in response to alterations in transcriptional activity. During decreasing transcriptional activity and reduced packing density of transcripts, the chromatin axis first condensed into nucleosomes and then into an approximately 30 nm thick higher order chromatin fiber. Packaging of the loop axis into supranucleosomal structures may contribute to the foreshortening and retraction of the loops observed during inhibition of transcription and in later stages of meiotic prophase. The increasing packing density of the DNA during the retraction process of the loops could also be visualized by immunofluorescence microscopy using antibodies to DNA. The dependence of the loop chromatin structure on transcriptional activity is discussed in relation to current views of mechanisms involved in gene activation.show moreshow less

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Metadaten
Author: Ulrich Scheer
URN:urn:nbn:de:bvb:20-opus-39304
Document Type:Journal article
Faculties:Medizinische Fakultät / Theodor-Boveri-Institut für Biowissenschaften
Language:English
Year of Completion:1987
Source:In: Biology of the Cell (1987) 59, 33-42.
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 57 Biowissenschaften; Biologie / 570 Biowissenschaften; Biologie
Tag:DNA antibodies; chromatin structure; electron microscopy; immunofluorescence microscopy; lampbrush chromosomes
Release Date:2009/11/20