Electrophoretic isolation of nucleosomes from <i>Dictyostelium</i> nuclei and nucleoli

Parish, Roger W.; Schmidlin, Sylvia; Fuhrer, Stelia; Widmer, Rosa M.

doi:10.1016/0014-5793(80)80081-0

Cited by 11 publications

(6 citation statements)

References 20 publications

(12 reference statements)

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“…4A) (31). These structures are very similar to ones previously observed by FISH as well as by silver staining, and suggest that multiple copies of the rDNA palindrome associate non-covalently in exponentially growing cells (16). We also treated cells with the microtubule-destabilizing drug nocodazole to examine arrested mitotic nuclei (26).…”

Section: Emery and Weiner (18) Previously Analyzed The Terminalsupporting

confidence: 79%

“…Curiously, the 8 Mb of rDNA within each cell which represents 20% of the nuclear DNA has remained unaccounted for in the microscopic examinations of mitotic nuclei described in the literature. rDNA monomers were assumed to be not detectable above the background staining in any DNA visualization technique using light microscopy, but the fact that the monomers are known to form higher order structures suggests that the rDNA should be visible (16).…”

Section: Discussionmentioning

confidence: 99%

“…The DNA in the palindromes is packaged into nucleosome-like higher order complexes observable under electron microscopy as`beads on a string' (15). Susceptibility of speci®c sites to nuclease digestion changes during different stages of the asexual life cycle, correlated with changes in the rate of rRNA synthesis (16,17). Sequences at the ends of the palindrome have short sequence repeats similar to the telomeres characterized at the ends of chromosomes (18).…”

Section: Introductionmentioning

confidence: 99%

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Sequence and structure of the extrachromosomal palindrome encoding the ribosomal RNA genes in Dictyostelium

Sucgang

Chen²,

Li³

et al. 2003

Nucleic Acids Research

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Ribosomal RNAs (rRNAs) are encoded by multicopy families of identical genes. In Dictyostelium and other protists, the rDNA is carried on extrachromosomal palindromic elements that comprise up to 20% of the nuclear DNA. We present the sequence of the 88 kb Dictyostelium rDNA element, noting that the rRNA genes are likely to be the only transcribed regions. By interrogating a library of ordered YAC clones, we provide evidence for a chromosomal copy of the rDNA on chromosome 4. This locus may provide master copies for the stable transmission of the extrachromosomal elements. The extrachromosomal elements were also found to form chromosome-sized clusters of DNA within nuclei of nocodazole-treated cells arrested in mitosis. These clusters resemble true chromosomes and may allow the efficient segregation of the rDNA during mitosis. These rDNA clusters may also explain the cytological observations of a seventh chromosome in this organism.

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Section: Emery and Weiner (18) Previously Analyzed The Terminalsupporting

confidence: 79%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Sequence and structure of the extrachromosomal palindrome encoding the ribosomal RNA genes in Dictyostelium

Sucgang

Chen²,

Li³

et al. 2003

Nucleic Acids Research

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“…Protein was recovered from the phenol phase and interphase by adding HC1 to 1N and 10 vol acetone. DNA and proteins were separated on gels as previously described (35,36).…”

Section: Siaterials and Methodsmentioning

confidence: 99%

“…The DNA of D.disg ideum is organised into nucleosomes (33)(34)(35)(36)(37)(38)(39)(40) and we wished to discover whether the lysine-rich protein was involved in the structure of the 100 A fiber. We had observed that mononucleosome populations obtained by micrococcal nuclease digestion contained two DNA sizes, one equivalent to the core (146 bp) and the second somewhat larger (166-180 bp) (33, [35][36][37][38]. One interpretation was that the larger sized particles carried a protein resembling Hi in function.…”

Section: Introductionmentioning

confidence: 99%

A lysine-rich protein functions as an H1 histone inDictyostelium discoideumchromatin

Parish

Schmidlin

1985

Nucl Acids Res

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Mononucleosomes released from Dictyostelium discoideum chromatin by micrococcal nuclease contained two distinctive DNA sizes (166-180 and 146 bp). Two dimensional gel electrophoresis suggested a lysine-rich protein protected the larger mononucleosomes from nuclease digestion. This was confirmed by stripping the protein from chromatin with Dowex resin. Subsequently, only the 146 bp mononucleosome was produced by nuclease digestion. Reconstitution of the stripped chromatin with the purified lysine-rich protein resulted in the reappearance of the larger mononucleosomes. Two-dimensional gel electrophoresis showed the protein was associated with mononucleosomes. Hence, the protein functions as an H1 histone in bringing the two DNA strands together at their exit point from the nucleosome. Trypsin digestion of the lysine-rich protein in nuclei resulted in a limiting peptide of approx. 10 kilodaltons. Trypsin concentrations which degraded the protein to peptides of 12-14 kilodaltons and partially degraded the core histones did not change the DNA digestion patterns obtained with micrococcal nuclease. Thus, the trypsin-resistant domain of the lysine-rich protein is able to maintain chromatosome structure.

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The Nucleus — Cytological Methods and Isolation for Biochemical Studies

Jackson¹

1985

Cell Components

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Electrophoretic isolation of nucleosomes from Dictyostelium nuclei and nucleoli

Cited by 11 publications

References 20 publications

Sequence and structure of the extrachromosomal palindrome encoding the ribosomal RNA genes in Dictyostelium

Sequence and structure of the extrachromosomal palindrome encoding the ribosomal RNA genes in Dictyostelium

A lysine-rich protein functions as an H1 histone inDictyostelium discoideumchromatin

The Nucleus — Cytological Methods and Isolation for Biochemical Studies

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