Ultrastructure and Function of Heterochromatin and Euchromatin

Frenster, John H.

doi:10.1016/b978-0-12-147601-4.50020-8

Cited by 47 publications

(21 citation statements)

References 35 publications

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“…TEM studies revealed that the nucleus of mature lymphocytes shows large domains of highly condensed and inactive heterochromatin. 25 Naturally, a high DNA and protein concentration can thus be expected in areas of the lymphocyte nucleus. This is directly evidenced in the Raman spectra.…”

Section: Resultsmentioning

confidence: 99%

Nonresonant Raman imaging of protein distribution in single human cells

et al. 2002

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A confocal Raman microscope is used to study the protein distribution inside biological cells. It is shown that high quality Raman imaging of the protein distribution can be obtained using confocal nonresonant Raman imaging ( exc ϭ 647.1 nm). The results are shown for two different human cell types. Perpheral blood lymphocytes are used as an example of the fully maturated cells with a low level of nuclear transcription. Human eye lens epithelial cells are used as an example of cells with a high level of nuclear activity. The protein distribution in both cell types is completely different. The nuclear distribution of the protein largely varies in the peripheral blood lymphocyte cells, while proteins are more homogenously distributed over the nuclear space in the eye lens epithelial cells. The imaging time is ϳ20 min for a field of view of 10 ϫ 10 m 2 . The size of the sampling volume is 1.4 fL using a full width at halfmaximum criterion along the z axis and a 1/e 2 criterion in the xy plane. The results presented here indicate that Raman imaging is particularly of interest in the study of cellular processes, like phagocytosis, apoptosis, chromatin compaction, and cellular differentiation, which are accompanied by relatively large-scale redistributions of the materials.

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Section: Resultsmentioning

confidence: 99%

Nonresonant Raman imaging of protein distribution in single human cells

et al. 2002

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“…Heterochromatic regions are thought to contain fewer genes and generally are less transcriptionally active than euchromatin (Muller and Painter 1932;Cooper 1959;Ananiev and Gvozdev 1974;Frenster 1974;Lakhotia and Jacob 1974;Hilliker et al 1980). Classical genetic analyses have indicated that there may be a functional basis to the conservation of NO location.…”

Section: Rdna Function and Chromosomal Locationmentioning

confidence: 99%

A Drosophila rRNA gene located in euchromatin is active in transcription and nucleolus formation.

Karpen¹,

Schaefer²,

Laird³

1988

Genes & Development

159

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P-element transformants of a single rRNA gene (rDNA) were used to investigate the relationship between the organization of the nucleolus organizer (NO) and rDNA function in Drosophila melanogaster. In situ hybridization to rRNA in polytene nuclei of salivary glands demonstrated that an rRNA gene can be transcribed at a high rate when inserted into chromosomal sites other than the NO. Structures that resemble morphologically the endogenous nucleoli ('mininucleoli') were associated with four different euchromatic sites of rDNA insertion. Molecular analyses revealed that these mininucleoli contained both rRNA and an antigen specific to nucleoli. Phenotypes resulting from rDNA deficiencies were rescued partially by the presence of the transformed rDNA, indicating that the transcripts and mininucleoli associated with the rDNA insertion sites were functional. Thus, two conserved features of rDNA organization in eukaryotes, namely tandem repetition and heterochromatic localization, are not required for rRNA gene function. We conclude that 'nucleolar organizing activity' is an intrinsic property of the rDNA or its RNA products.

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“…The methods used in this study were chosen because of their simplicity and the fact that they provided us with a heavily transcribed and weakly transcribed form of chromatin . Although both types of chromatin have a similar basic structure, nucleosomes and linkers, subtle differences exist between the two types of chromatin, differences in configuration (Frenster 1974, Baserga and Nicolini 1976, Gottesfeld and Bonner 1977, presence of acidic proteins, RNA polymerases, etc . ; these differences between transcribable and nontranscribable chromatin could be associated with differences in the incidence of the formation of thymine dimers .…”

Section: Discussionmentioning

confidence: 99%