“Cytoplasmic” DNA from primary embryonic cell cultures is not informational

Williamson, Robert; McShane, Theresa; Grunstein, Michael; Flavell, R.A.

doi:10.1016/0014-5793(72)80029-2

Cited by 10 publications

(5 citation statements)

References 19 publications

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“…Similar results are obtained upon examination of the situation in the postribosomal particle fraction. In any event, the present experiments confirm the findings of various authors [4,6,8,9,14,15,36 -411 that the postmitochondria1 supernatants of eukaryotic cells, duck erythroid cells in our case, contain small-molecularweight DNA. We have studied the sedimentation behaviour of the nuclear and cytoplasmic nonmitochondrial DNA fractions as well as their specific activities of labeling with 32P1.…”

Section: Discussionsupporting

confidence: 91%

“…Considering that the fractionation procedures will inevitably result in contamination of the fast-labeled small-molecularweight nuclear DNA by the bulk nuclear DNA, we think that the former are similar to the cytoplasmic nonmitochondrial DNA molecules. Our results, as well as those of others [5,6,8,9,, strongly suggest that the cytoplasmic nonmitochondrial DNA is synthesized in the nucleus. Duck erythroid cytoplasm contains less than 0.5 % of total cellular nonmitochondrial DNA as the fast-labeled small-molecular-weight DNA compared to 0.5-1.00/, in Chang liver cells [39], and 0.5-2.0% in human lymphocytes [36-38,411.…”

Section: Discussionsupporting

confidence: 89%

“…In this hypothesis, the synthesis of informational DNA amounts to amplification of a limited portion of the genome. However, re-association studies, on nuclear and cytoplasmic DNA of human lymphocytes [36,37], HeLa cells [9], chick embryo cells [9], hamster embryo cells [8] and mouse embryo cells [6] given different results. In similar studies [20] (and unpublished), we find that nuclear and cytoplasmic DNA contain almost the same amount of unique DNA with identical renaturation rates.…”

Section: Discussionmentioning

confidence: 99%

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DNA Synthesis in Circulating Erythroblasts of Anemic Duck

Modak

Commelin

Grosset

et al. 1975

European Journal of Biochemistry

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In the circulating blood of anemic ducks, 5 % of all erythroid cells synthesize DNA. Immature erythroblasts, at all stages of differentiation, synthesize DNA although to a varying degree, while reticulocytes and erythrocytes do not. In the erythroid cell population labeled in vitro 2 h with 32Pi, half of the labeled DNA sediments as small-molecular-weight molecules, suggesting that these molecules fail to integrate into the high-molecular-weight components.Labeled DNA is found in the cytoplasmic postmitochondrial fractions and it is in a form of deoxyribonucleoproteins which cosediment with ribosomes as well as subribosomal particles in sucrose gradients. However, fixation with HCHO and centrifugation to equilibrium in CsCl gradient of these particles shows that the deoxyribonucleoprotein bands at the density different than the ribosomes and, thus, not physically linked to them. In EDTA-dissociated ribosomes, the deoxyribonucleoprotein particles cosediment with ribosomal subunits in such a way that the larger the particle, the larger the molecular weight of the DNA cosedimenting with it.The specific radioactivity of the cytoplasmic ribosome-derived and postribosomal-particlederived DNAs and the small molecular-weight nuclear DNA is similar and 10-20-fold higher than that of the bulk nuclear DNA. The former three DNA species sediment between 4-14 S. It is concluded that the cytoplasmic nonmitochondrial DNA species are of the nuclear origin. Less than 0.5 % of the total cellular nonmitochondrial DNA can be purified from the nucleus and the cytoplasm as fast-labeled small-molecular-weight components. All of the cellular nonmitochondrial DNA species band at the same mean buoyant density in Cs2S0,/urea gradients. All behave as native structures in hydroxyapatite and contain less than 5 "/, of their length as single-stranded regions. down product of the nuclear DNA. Furthermore, Fromson and Nemer [7] have attributed the presence of DNA in cytoplasmic nonmitochondrial fractions to contamination by a nuclear leakage. The problem, however, remains unsolved due to recent findings by Koch [8,9] that when compared to the nuclear DNA, the cytoplasmic DNA seems to be relatively enriched in unique sequences.The transfer of the products of transcription from the nucleus to the cytoplasm in the form of mRNA and its translation on ribosomes has been extensively investigated, for instance in avian erythroid cells [lo, 111. The primary transcription product of the globin genes is of the size 5 x lo6 daltons [12,13] and is suggested to be the precursor of the cytoplasmic mRNA (pre-mRNA). Although there is little doubt about the role of this pre-mRNA as intermediary in cellular information transfer, a straightforward scheme of direct

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Section: Discussionsupporting

confidence: 91%

Section: Discussionsupporting

confidence: 89%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

DNA Synthesis in Circulating Erythroblasts of Anemic Duck

Modak

Commelin

Grosset

et al. 1975

European Journal of Biochemistry

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“…A somewhat higher content (1.5 -2-fold) of transfer and ribosomal RNA sequences has been found in the microsome-associated liver DNA [4]. In contrast, cytDNA from primary embryonic liver cells reassociated at exactly the same rate as nDNA [15].…”

Section: Discussionmentioning

confidence: 99%

“…If any of the cytDNA species described had an informational role, it should have contained only a small proportion of the total nucleotide sequences of the genome. Thus, microsomal DNA does not seem to be informational, since it was shown to resemble nDNA closely in its base composition [8] and reassociation rate [15]. On the other hand, even though the lymphoid cell membrane DNA had the same buoyant density as nDNA it was shown to have quite different reassociation kinetics indicating the presence of different frequencies of certain nucleotide sequences [12].…”

mentioning

confidence: 99%

Characterization of Cytoplasmic DNA of Mouse‐Myeloma Cells

Solage

Laskov

1975

European Journal of Biochemistry

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Cytoplasmic DNA from mouse myeloma cells comprised between 1 % and 2 % of the total cellular DNA. Detergent-prepared cytoplasmic lysate consisted mainly of 8-S and 22-S species. While these DNA species were present in the 13 000 x g pellet of the detergent-prepared cytoplasmic lysate, only the light DNA species was present in the 13000 x g supernatant fraction. In neutral CsCl gradients the DNA of both cytoplasmic fractions had a buoyant density of 1700 g/cm3, which is identical to that of nuclear DNA.The similarity between the cytoplasmic and nuclear DNA was also demonstrated by analysis on alkaline CsCl gradients. A small proportion of closed-circular DNA, presumably of mitochondrial origin, was demonstrated only in cytoplasmic fraction obtained from mechanically disrupted cells and not in detergent-prepared cytoplasmic lysate. It was found that poly(A)-containing mRNA and 28-S ribosomal RNA hybridized to about the same extent to the cytoplasmic DNA as compared to nuclear DNA. The results indicate that most of the cytoplasmic DNA in myeloma cells is similar to nuclear DNA and does not consist of mitochondrial DNA. Several classes of cytDNA, different from mtDNA, have been demonstrated in mammalian cells. Rapidly labeled DNA has been found to be associated with the microsomal subcellular fraction [l-51 and to form DNA protein particles in various cell types [5,6]. Evidence has been presented indicating that this DNA was leaking from nuclei damaged in the course of cell fractionation [4,7]. This possibility, however, was not supported by the finding that microsomal DNA has a higher turnover rate compared to that of nDNA [l-4,8], and that the two DNAs can be differentially inhibited by inhibitors of DNA synthesis [9,10]. A second type of cytDNA has been reported to be associated with the outer cell membrane of a human lymphoid cell line [ll]. In contrast to microsomal DNA this DNA was labeled at a lower rate than nDNA [12,13]. More recently Smith and Vinograd [14] have demonstrated a small polydisperse closed-circular DNA in the cytoplasm of HeLa and other mammalian cells, distinguishable from mtDNA by size and buoyant density. The function of these cyt-DNA species is still obscure. It has been suggested that microsomal DNA has an informational role [5] and that membrane-associated DNA may participate in the transfer of the antigenic signal from the outer membrane of the Abbreviations Cytoplasmic DNA, cytDNA; nuclear DNA, nDNA; mitochondria1 DNA, mtDNA. lymphoid cell to its nucleus [ll]. If any of the cytDNA species described had an informational role, it should have contained only a small proportion of the total nucleotide sequences of the genome. Thus, microsomal DNA does not seem to be informational, since it was shown to resemble nDNA closely in its base composition [8] and reassociation rate [15]. On the other hand, even though the lymphoid cell membrane DNA had the same buoyant density as nDNA it was shown to have quite different reassociation kinetics indicating the presence of different frequencies of c...

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Actinomycin D inhibits hemoglobin synthesis in rabbit reticulocyte lysates and binds to a 15 S cytoplasmic particle involved in the initiation step of translation

Felicetti

Urbani

1977

Biochimica et Biophysica Acta (BBA) - Nucleic Acids and Protein

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“Cytoplasmic” DNA from primary embryonic cell cultures is not informational

Cited by 10 publications

References 19 publications

DNA Synthesis in Circulating Erythroblasts of Anemic Duck

DNA Synthesis in Circulating Erythroblasts of Anemic Duck

Characterization of Cytoplasmic DNA of Mouse‐Myeloma Cells

Actinomycin D inhibits hemoglobin synthesis in rabbit reticulocyte lysates and binds to a 15 S cytoplasmic particle involved in the initiation step of translation

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