Sub-nuclear components of Physarum polycephalum

Bradbury, E. Morton; Matthews, Harry R.; McNaughton, J.; Molgaard, H. V.

doi:10.1016/0005-2787(74)90236-6

Cited by 24 publications

(7 citation statements)

References 15 publications

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“…Preparation of rDNA. Nuclei of Physarum (strain a x i) microplasmodia, grown in 3 to 5 5L flasks (10) were isolated as previously described (3,11). Nuclei were then disrupted by passage through a French pressure cell at 8000 psi (12), and nucleoli prepared essentially as described by Mohberg and Rusch (11).…”

Section: Methodsmentioning

confidence: 99%

Unique sequence arrangement of ribosomal genes in the palindromic rDNA molecule of Physarum polycephalum

et al. 1979

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R-loop and restriction mapping procedures reveal the organization of coding regions at each end of the giant rDNA palindrome of Physarum polycephalum. A 19S coding region of 2.10 +/- 0.21 kb is located at each end of a very long central spacer (35.64 +/- 2.08 kb). An internal spacer of 1.66 +/- 0.12 kb lies distal to the 19S gene. The 5.8S rRNA coding region is located in this spacer. The 26S gene lies distal to the internal spacer. The 26S gene is unusual among those of eukaryotes in that it consists of 3 coding regions (alpha, beta and gamma) interrupted by 2 intervening sequences. The 26S alpha (most central) coding segment of 2.41 +/- 0.33 kb is separated from the 26S beta segment by an intervening sequence of 0.68 +/- 0.13 kb. The 26S beta segment (0.70 +/- 0.11 kb) is separated from the most distal 26S gamma segment (0.59 +/- 0.14 kb) by an intervening sequence of 1.21 +/- 0.14 kb. The 2 intervening sequences are present in at least 88% of ribsomal genes from active plasmodia, indicating that genes containing these sequences are transcribed. The rDNA termini contain a heterogeneous region which varies in length by +/- 300 base pairs.

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Section: Methodsmentioning

confidence: 99%

Unique sequence arrangement of ribosomal genes in the palindromic rDNA molecule of Physarum polycephalum

et al. 1979

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“…e ribosomal genes of Physarum polycephalum are located on an extrachromosomal, nucleolar satellite DNA molecule of ~61 kilobase pairs (kb)1 of DNA (Braun & Evans, 1969; Newlon et al, 1973;Bradbury et al, 1973;Molgaard et al, 1976;Vogt & Braun, 1976; Grainger & Ogle, 1978). The rDNA molecule is a palindrome with the rRNA coding regions arranged symmetrically about a large central spacer (Molgaard et al, 1976;Campbell et al, 1979).…”

Section: Initiation Of Transcription Of Ribosomal Deoxyribonucleic Acidmentioning

confidence: 99%

“…Fragments. Nuclei were isolated from microplasmodia according to the procedure of Mohberg & Rusch (1971) as modified by Bradbury et al (1973). Nucleoli were isolated by centrifugation through a cushion of 1.0 M sucrose, 1 mM CaCl2, and 10 mM Tris-HCl, pH 7.4 (Mohberg & Rusch, 1971), following disruption of nuclei by passing through a French pressure cell at 8000 psi at a concentration of 2.5 X 108 nuclei/mL in 0.25 M sucrose, 2.0 mM EDTA, and 10 mM Tris-HCl, pH 7.4, at 4 °C.…”

Section: Purification Of Rdna and Separation Of Restrictionmentioning

confidence: 99%

Initiation of transcription of ribosomal deoxyribonucleic acid sequences in isolated nuclei of Physarum polycephalum: studies using nucleoside 5'-[.gamma.-S]triphosphates and labeled precursors

Sun¹,

Johnson²,

Allfrey³

1979

Biochemistry

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“…Chromosome counts (Mohberg et al 1973) showed that plasmodia of CL (and other Colonia isolates) have 35-40 chromosomes whereas axi plasmodia have predominantly nuclei with 45-50 or 75-80 chromosomes. Bradbury et al (1973), however, reported a chromosome number of 22 for axi plasmodia.…”

Section: Discussionmentioning

confidence: 86%

Plasmodium formation without change in nuclear DNA content inPhysarum polycephalum

Cooke

Dee

1974

Genet. Res.

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The Colonia isolate of Physarum polycephalum produces plasmodia within amoebal clones. Wheals demonstrated genetically that amoebae of the C50 strain of this isolate, when crossed with heterothallic amoebae, yielded recombinant progeny. He concluded that nuclear fusion and meiosis occurred in these crosses and suggested that nuclear fusion was also involved in plasmodia formation in clones. He thus designated the strain 'homothallic'.In the present work genetic evidence is presented which indicates that the Colonia strain CL, when crossed with heterothallic strains, also yields recombinant progeny and thus undergoes nuclear fusion and meiosis. Microdensitometric measurements of nuclear DNA content are reported which indicate that CL amoebae are haploid like heterothallic amoebae, and crossed plasmodia are diploid. However, clonally formed CL plasmodia were found to have the same G 2 nuclear DNA content as CL amoebae. This observation excludes the possibility of nuclear fusion when plasmodia form within clones of CL amoebae and therefore the strain cannot be homothallic. Two alternatives, apogamy and coalescence, are proposed as the most likely mechanisms for clonal plasmodium formation in strain CL.

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Sub-nuclear components of Physarum polycephalum

Cited by 24 publications

References 15 publications

Unique sequence arrangement of ribosomal genes in the palindromic rDNA molecule of Physarum polycephalum

Unique sequence arrangement of ribosomal genes in the palindromic rDNA molecule of Physarum polycephalum

Initiation of transcription of ribosomal deoxyribonucleic acid sequences in isolated nuclei of Physarum polycephalum: studies using nucleoside 5'-[.gamma.-S]triphosphates and labeled precursors

Plasmodium formation without change in nuclear DNA content inPhysarum polycephalum

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