Novel Properties of Satellite DNA from Muskmelon

Bendich, Arnold J.; Anderson, Robert S.

doi:10.1073/pnas.71.4.1511

Cited by 40 publications

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References 44 publications

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“…Additional washes showed no further elution of radioactivity. After diluting to correct for salt differences, radioactivity was measured by using 4 …”

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Chloroplast DNA Sequence Homologies among Vascular Plants

Lamppa¹,

Bendich²

1979

Plant Physiol.

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The extent of sequence conservation in the chloroplast genome of higher plants has been investigated. Supercoiled chloroplast DNA, prepared from pea seedlings, was labeled in vitro and used as a probe in reassociation experiments with a high concentration of total DNAs extracted from several angiosperms, gymnosperms, and lower vascular plants. In each case the probe reassociation was accelerated, demonstrating that some chloroplast sequences have been highly conserved throughout the evolution of vascular plants. Only among the flowering plants were distinct levels of cross-reaction with the pea chloroplast probe evident; broad bean and barley exhibited the highest and lowest levels, respectively. With the hydroxylapatite assay these levels decreased with a decrease in probe fragment length (from 1,860 to 735 bases), indicating that many conserved sequences in the chloroplast genome are separated by divergent sequences on a rather fine scale. Despite differences observed in levels of homology with the hydroxylapatite assay, SI nuclease analysis of heteroduplexes showed that outside of the pea family the extent of sequence relatedness between the probe and various heterologous DNAs is approximately the same: 30%. In our interpretation, the fundamental changes in the chloroplast genome during angiosperm evolution involved the rearrangement of this 30% with respect to the more rapidly changing sequences of the genome. These rearrangements may have been more extensive in dicotyledons than in monocotyledons. We have estimated the amount of conserved and divergent DNA interspersed between one another.From the reassociation experiments, determinations were made of the percentage of chloroplast DNA in total DNA extracts from different higher plants; this value remained relatively constant when compared with the large variation in the diploid genome size of the plants.Analysis by restriction endonucleases has shown differences in the fine structure of the chloroplast genome in a variety of higher plants (1). However, restriction enzyme maps can be altered by a single nucleotide substitution (29)

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“…Additional washes showed no further elution of radioactivity. After diluting to correct for salt differences, radioactivity was measured by using 4 …”

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confidence: 99%

Chloroplast DNA Sequence Homologies among Vascular Plants

Lamppa¹,

Bendich²

1979

Plant Physiol.

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“…Indeed, in some plants, sequences complementary to ribosomal RNA appear to be concentrated in the satellite band (4,10). These have been estimated to account for perhaps 15%o of the satellite in muskmelon (8), and to contain cistrons for both cytoplasmic and chloroplastic rRNAs in pumpkin (11). Other rapidly reannealing and repetitive satellite DNA sequences whose functions were not determined have also been described (7,8).…”

Section: Discussionmentioning

confidence: 99%

“…8). Indeed, in some plants, sequences complementary to ribosomal RNA appear to be concentrated in the satellite band (4,10).…”

Section: Discussionmentioning

confidence: 99%

“…In this regard, several higher plants, including cucumber, have previously been shown to contain particularly large amounts (up to 44%) of satellite DNAs in neutral CsCl (4)(5)(6)(7)(8). These large plant satellites-in analogy with the satellite DNAs of animal cells (9)-have variously been reported to be rapidly renaturing (4,7,8,10), associated with the genes for rRNA (4,11) and of nuclear origin (7,10,12). The relationship between cytoplasmic organelle DNA and the large plant satellites, however, was not seriously investigated.…”

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Satellite-Rich DNA in Cucumber: Hormonal Enhancement of Synthesis and Subcellular Identification

Kadouri¹,

Atsmon²,

Edelman³

1975

Proc. Natl. Acad. Sci. U.S.A.

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Cucumber hypocotyl DNA in neutral CsCl distributes into a mainband comprising 59% of the total, and two large satellite bands which contribute 41%to the DNA pattern. Organelle enrichment studies show that the densities of mitochondrial and chloroplast DNA coincide with those of the satellite bands. At least 12-19% of total cucumber DNA is associated with the cytoplasmic organelles. These In prior studies, gibberellin-induced elongation of the cucumber hypocotyl was correlated with an increased incorporation of [3H]thymidine into DNA (1). Autoradiographic and fractionation experiments (2) further suggested that much of this synthesis might be extranuclear, reflecting a hormoneenhanced multiplication of chloroplasts in the elongating zone (3). This possibility has now been investigated at the level of different DNA density peaks by CsCl gradient centrifugation. In this regard, several higher plants, including cucumber, have previously been shown to contain particularly large amounts (up to 44%) of satellite DNAs in neutral CsCl (4-8). These large plant satellites-in analogy with the satellite DNAs of animal cells (9)-have variously been reported to be rapidly renaturing (4,7,8,10), associated with the genes for rRNA (4, 11) and of nuclear origin (7,10,12). The relationship between cytoplasmic organelle DNA and the large plant satellites, however, was not seriously investigated.In the present report we demonstrate that a considerable fraction of the large satellite DNAs in cucumber are associated with chloroplasts and mitochondria. We further show that in elongating hypocotyl tissue the rates of synthesis of organelle-rich satellite DNA and mainband DNA respond in vivo to hormone treatments by increasing markedly. Alternatively (method 2), hypocotyl sections were processed as described by Tautvydas (17) except that steeping was carried out at 0-2°in 4% gum arabic, 0.4 M sucrose, 6 mM Mg acetate, 0.3 mM dithiothreitol, and 5 mM morpholinoethane sulfonate, pH 6.4. Resuspension buffer was without gum arabic and contained 0.15% 2-ethyl-1-hexanol. Method 3 was identical to method 2 except that 0.1% Triton X-100 was included during the steeping procedure. For the isolation of chloroplasts the filtered homogenate was centrifuged at 1000 X g, and the pellet was dispersed in modified Honda medium supplemented with 40 mM Mg+2 and incubated with DNase (70 ug/ml) at 0°for 15-20 min. After addition of 0.1 M EDTA, discontinuous sucrose gradient centrifugation was carried out (2). For the isolation of mitochondria filtered homogenate was centrifuged at 5000 X g for 5 min and the supernatant was recentrifuged at 23,500 X g for 20 min.The 23,500 X g pellet was treated with DNase as described for chloroplasts and then rinsed in Tris-saline-EDTA.

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“…copies of about 450 base-pairs complexity, and a thermolabile heterogeneous component which reassociates almost 10000-times more slowly, indicating a few hundred copies with a sequence complexity of 3 x 106 base-pairs (Bendich & Anderson, 1974;Sinclair et al, 1975 , 1977). It remained unresolved, however, whether interspersion could account for the anomalous physical properties of these fractions.…”

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Divergence, differential methylation and interspersion of melon satellite DNA sequences

Reis¹,

Timmis²,

Ingle³

1981

Biochemical Journal

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Melon (Cucumis melo) satellite DNA consists of two components, Q and S, each with a buoyant density in CsCl of 1.707g/ml, but differing by 90C in 'melting' temperature. These physical properties appear to be in contradiction, since both depend on G + C content. In order to resolve this anomaly, base compositions were directly determined for isolated fractions. The low-'melting' component S contains 41.8% G + C, with 6% of C present as 5-methylcytosine, whereas Q DNA contains 54% G + C, with 41% of C methylated. Analyses of restriction-site loss agreed well with the direct determinations of methylation and divergence, and indicated some clustering of methylated sites in Q DNA. Analysis of restricted main-band DNA by hybridization with RNA complementary to Q satellite DNA ('Southern transfer') showed satellite Q tandem arrays interspersed in DNA of main-band density. Sequence divergence and extent of methylation did not appear to depend on whether a repeat array was present as satellite or interspersed in main-band DNA. Hybridization in situ indicated considerable heterpgeneity in the genomic proportion of the Q-DNA sequences in melon fruit nuclei, implying over-and under-representation consistent with extensive unequal recombination in satellite Q tandem arrays. The cucumber, Cucumis sativus, contains less than 8% as much Q-homologous DNA per genome as the melon, suggesting rapid evolutionary gain or loss of these tandem repeat sequences.Melon (Cucumis melo) DNA contains a symmetrical DNA satellite peak at 1.707g/ml in CsCl isopycnic gradients, well-resolved from main-band DNA at 1.693g/ml (Sinclair et al., 1975). The quantity of this satellite fraction varies between varieties of melon, melon tissues and during development (Pearson et al., 1974

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Novel Properties of Satellite DNA from Muskmelon

Cited by 40 publications

References 44 publications

Chloroplast DNA Sequence Homologies among Vascular Plants

Chloroplast DNA Sequence Homologies among Vascular Plants

Satellite-Rich DNA in Cucumber: Hormonal Enhancement of Synthesis and Subcellular Identification

Divergence, differential methylation and interspersion of melon satellite DNA sequences

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