Showing papers on "Nuclear DNA published in 1971"
TL;DR: It is suggested that DNA influences development in two ways, first directly through its informational content, and second indirectly by the physical mechanical effects of its mass independent of its informationalcontent.
Abstract: A survey of work on meiotic duration in diploid plants shows that the duration is positively correlated with the DNA content per nucleus and with the mitotic cycle time. However, meiotic duration is not solely determined by the DNA content per nucleus but is also affected by chromosomal organization, DNA structure and the developmental pattern of the organism. Thus, in three polyploid plant species meiosis is much shorter and in three animal species it is much longer than would be expected in diploid plant species having corresponding DNA contents. Differences in meiotic duration in plant species are usually the result of proportional differences in all the stages of meiosis. Factors affecting the initiation, control and duration of meiosis are discussed. The consequences of changes in nuclear DNA content on developmental processes and the life cycle in plants are considered. It is suggested that DNA influences development in two ways, first directly through its informational content, and second indirectly by the physical mechanical effects of its mass independent of its informational content.
297 citations
TL;DR: Alkali-denatured nuclear DNA of C. aethiops cells elutes as three peaks and nucleolar DNA as one peak from methylated albumin kieselguhr chromatography columns with linear salt and pH elution gradients as well as the restriction in the ability to bind the polyribonucleotides.
143 citations
TL;DR: A denaturation map of 5S DNA analyzed by electron microscopy demonstrates that the repeating pattern is regular and each repeating unit has a mass of about 500,000 daltons, equivalent to about 24,000 repeating units for each haploid complement of DNA.
Abstract: DNA containing the multiple genes for 5S RNA has been isolated from the genome of Xenopus laevis. Whereas 5S RNA is about 57% G + C, the 5S DNA has a base composition of about 33-35% GC and consists of two alternating regions that differ in base composition by at least 20% GC. A denaturation map of 5S DNA analyzed by electron microscopy demonstrates that the repeating pattern is regular and each repeating unit has a mass of about 500,000 daltons. If one gene for 5S RNA (84,000 daltons native) were present in each repeat, it should comprise about 16.8% of 5S DNA. This arrangement is confirmed, since 6.8% of pure 5S DNA (13.6% of its base pairs) hybridized with 5S RNA. The remaining 83% of each repeating unit is considered to be “spacer” DNA. The 5S RNA hybridizes with about 0.05% of the bulk DNA of X. laevis, so that 5S DNA comprises about 0.7% of the total nuclear DNA. This is equivalent to about 24,000 repeating units for each haploid complement of DNA. These repeats are highly clustered; as many as 86 have been visualized along a single DNA molecule.
139 citations
120 citations
TL;DR: It is concluded that the multiplicity of specific repetitive genes varies out of proportion with the DNA content, contrary to expectation based on simple polyteny.
Abstract: The diploid nuclear DNA contents in eight species of fish have been found to differ over a 178-fold range. Among these, lungfish have the highest values, and teleosts have the lowest. Shark and coelacanth have intermediate values, which are close to the highest teleost values. Such great variation in DNA contents among vertebrates indicates that fundamental differences in chromosome structure and DNA function have arisen during evolution.
In order to gain insight into the organization of genes in organisms with different DNA contents, the relative proportion of the genome coding for ribosomal RNA was determined for five species, winter flounder, goldfish, rainbow trout, dogfish shark, and Australian lungfish. The proportion of ribosomal DNA (r-DNA) was found to vary over a six-fold range from flounder to lungfish. In general, species with higher DNA contents have lower proportions of r-DNA. The r-DNA proportion of trout is consistent with the view that salmonids are recent tetraploids. If the goldfish is also considered a tetraploid, then its r-DNA proportion indicates a loss of ribosomal genes subsequent to polyploidization. Measurement of the ribosomal genes in fish DNA's was based on hybridization with yeast ribosomal RNA, which was assumed to be equally homologous with the r-DNA of all species studied.
The activity of multiple copies of genes was studied by measuring the volumes of blood cells in five species. It was found that erythrocyte volume correlated both with ribosomal gene multiplicity and with total DNA content. The size of goldfish and trout erythrocytes suggests that cell volume in these tetraploids has declined to the ancestral diploid level.
It is concluded that the multiplicity of specific repetitive genes varies out of proportion with the DNA content, contrary to expectation based on simple polyteny. This variation in the proportions of specific genes and the large variations in total DNA content among fish are thought to be due to a combination of tetraploidy and extensive linear replication of specific chromosomal regions during evolution.
104 citations
TL;DR: A species of DNA that is apparently associated with the plasma membrane of diploid human lymphocytes that are continously growing is described.
Abstract: A species of DNA that is apparently associated with the plasma membrane of diploid human lymphocytes that are continously growing is described. This DNA differes from nuclear or mitochondrial DNA by virtue of its location in the cell, time of synthesis in the cell cycle, and various physical properties. At present, the role of this DNA is unknown.
90 citations
TL;DR: On the basis of nuclear DNA content, the giant neurons R-2, P-1, and L-6 of adult animals can each be divided into at least two populations and it is suggested that much and perhaps all of the genome replicates repeatedly during the growth and development of these neurons and that each replication is synchronous.
Abstract: The nuclei of the giant neurons of the marine mollusk Aplysia californica can contain more than 0.2 microgram of DNA. This is more than 200,000 times as much DNA as the haploid amount found in Aplysia sperm. On the basis of nuclear DNA content, the giant neurons R-2, P-1, and L-6 of adult animals can each be divided into at least two populations. The mean DNA content of these two populations (0.067 and 0.131 microgram of DNA) are approximately related by a factor of 2. This suggests that much and perhaps all of the genome replicates repeatedly (up to 16 times) during the growth and development of these neurons and that each replication is synchronous. The enormous amount of DNA in these cells opens up the possibility of characterizing the DNA and other constituents of chromatin from individual but phenotypically different neurons.
84 citations
TL;DR: In this article, DNA from calf liver by Cs 2 SO 4 -Ag + density gradient gradient centrifugation revealed a minor heavy peak (7% of the total DNA) at a density of 1.57 g
84 citations
TL;DR: In this paper, the synthesis of mitochondrial and nuclear DNA during the growth of synchronously dividing cultures of Saccharomyces cerevisiae was followed by analytical isopycnic centrifugation in CsCl as well as by pulse labelling with radioactive adenine and determination of the rate of incorporation into each DNA component at different stages of growth.
81 citations
TL;DR: Although circular molecules represent only 1 to 5 % of the total DNA, they can be prepared in sizable and reproducible amounts by a method based on the use of mechanical disruption of yeast cells rather than lysis by snail gut juice.
74 citations
TL;DR: DNA intermediates studied in the synthesis of adenovirus type 2 deoxyribonucleic acid (DNA) were of viral origin and were made at a stage of the cell cycle when host DNA is not synthesized.
Abstract: Intermediates in the synthesis of adenovirus type 2 deoxyribonucleic acid (DNA) were studied in HeLa cells. Pieces of DNA smaller than the viral genome were demonstrated after labeling with (3)H-thymidine for 10 to 240 sec. Intermediates as small as the Okazaki fragments (8 to 10S) do not predominate at any of the above times. No detectable addition of nucleotides to parental genome could be shown, nor was there any breakdown of recently synthesized viral DNA. The DNA intermediates were of viral origin for they hybridized to viral DNA and were made at a stage of the cell cycle (G(2)) when host DNA is not synthesized.
TL;DR: Control of DNA replication by short-lived, newly synthesized proteins could explain the confinement of major nuclear DNA replication to the S period as well as the temporal order of the synthesis of this DNA in Physarum.
TL;DR: The nuclear DNA of D. melanogaster contains DNA sequences that are repeated between ten and a hundred times more often than the next class of redundant DNA, which has been localized by "in situ" hybridization in the chromocenter of the chromosomes of the salivary gland.
Abstract: The nuclear DNA of D. melanogaster contains DNA sequences that are repeated between ten and a hundred times more often than the next class of redundant DNA. This DNA, as a renatured duplex isolated on the basis of its renaturation kinetics, has a buoyant density of 1.691 (g/ml). In its native state it bands within the unique nuclear DNA peak (ρ = 1.701). These sequences have been localized by “in situ“ hybridization in the chromocenter of the chromosomes of the salivary gland. The properties of centromeres are discussed in terms of the occurrence of repeated sequences at this locus.
TL;DR: A large proportion of pseudovirion RNA is complementary to both chloroplast and nuclear DNA, suggesting that chloropstroke DNA has many nucleotide sequences in common with nuclear DNA.
TL;DR: When HeLa cells were exposed to EB at a concentration of 0.1 μg/ml or higher for 48 h, newly synthesized mitochondrial DNA could not be detected by isopycnic centrifugation in CsCl-EB solution.
TL;DR: The association between DNA and plant weight is complete and the effects of some other environments on the amount of nuclear DNA are described here.
Abstract: ENVIRONMENTALLY induced changes in plant weight in the flax varieties, Stormont Cirrus and Stormont Motley (Durrant, 1962, 1971), are accompanied by changes in amount of nuclear DNA (Evans, Durrant and Rees, 1966; Evans, 1968). The large genotroph (L) induced by growing plants of the plastic genotroph (P1) in the specific inducing environment of high soil nitrogen has approximately 16 per cent. more nuclear DNA than the small genotroph (5) induced by growing P1 plants in high soil phosphorus. The L genotroph is up to six times the size of the S genotroph depending on the environments in which they are grown, but both L and S breed true in plant weight irrespective of the environments in which subsequent generation are grown. The P1 genotroph is intermediate in plant weight and in amount of nuclear DNA. The induced change in plant weight must occur early in the development of the P1 genotroph when grown in an inducing environment, probably before flower primardia are formed at the sixth week, because plants grown from seed from all capsules, developing over a long period, are identically changed. A week-by-week study of P1 plants grown in the specific inducing environments of high soil nitrogen on the one hand, and high soil phosphorus on the other, showed a gradual divergence in the amounts of nuclear DNA reaching the maximum difference of 16 per cent. at the fifth week, in parallel with the induced changes in plant weight thought to occur during this period. Similarly, the selection of large and small plants from the F2 to F5 of reciprocal crosses between L and S produced a divergence in plant weight and a correlated divergence in amount of nuclear DNA. In these studies, therefore, the association between DNA and plant weight is complete. The effects of some other environments on the amount of nuclear DNA are described here. They are environments which induce non-permanent changes in DNA, and environments which cause reversion of previously induced changes in DNA.
TL;DR: The 4C nuclear DNA content was estimated for 17 wild Hordeum species and five cultivated Hordeum vulgare varieties which were chosen to include examples varying greatly in geographical origin and in morphological and physiological characters, and it is concluded that the DNA content of diploid hordeum species is invariable.
Abstract: The 4C nuclear DNA content was estimated for 17 wild Hordeum species and five cultivated Hordeum vulgare varieties which were chosen to include examples varying greatly in geographical origin and in morphological and physiological characters. Nuclear DNA was measured on an integrating microdensitometer using prophase nuclei in Feulgen stained root-tip squashes. There were no significant differences in DNA content between any or the 15 diploid genotypes measured, and the seven polyploid genotypes all had nuclear DNA contents which were simple multiples of the diploid genotypes. This result, namely that the DNA content of diploid Hordeum species is invariable, differs from results obtained from diploid species in several other plant genera which differed greatly in nuclear DNA content.
TL;DR: Two DNA-dependent RNA polymerases of nuclear origin have been purified from leaves of Zea mays and can be resolved by DEAE-chromatography or glycerol-gradient centrifugation into two components, one of which prefers native DNA, while the other prefers denatured DNA.
Abstract: Two DNA-dependent RNA polymerases of nuclear origin have been purified from leaves of Zea mays The two enzymes can be separated on DEAE-cellulose columns Enzymes I and II are eluted with 008 and 020 M (NH4)2SO4, respectively Both enzymes prefer maize nuclear DNA as a template; they are also more active in the presence of Mg++ than Mn++ and are inhibited by (NH4)2-SO4 or KCl Neither enzyme is inhibited by rifamycin SV Enzyme II is strongly inhibited by α-amanitin, whereas enzyme I is not significantly affected Their ability to use native and denatured DNA as templates varies according to the extent and method of purification of the polymerase Furthermore, enzyme II can be resolved by DEAE-chromatography or glycerol-gradient centrifugation into two components, one of which prefers native DNA, while the other prefers denatured DNA
TL;DR: Evidence is presented to show that the major soluble and the nuclear DNA polymerases of rat liver are, in fact, two distinct entities, and the minor soluble polymerase appears similar in properties to the nuclear enzyme.
TL;DR: Almost 0.5% of exogenous DNA initially available was recovered in a partially degraded but nevertheless high molecular weight state from the nuclear fraction of tobacco cells, and the remainder appeared to be very extensively degraded, andThe breakdown products were largely found within the cells.
Abstract: 1. (1) The uptake of Pseudomonas aeruginosa DNA by pea seedlings, and uptake of tobacco DNA or P. aeruginosa DNA by tobacco cells in shake cultures has been investigated. The fate of the DNA has been followed by CsCl density gradient equilibrium centrifugation, using radiolabeled donor DNA of high density. 2. (2) Pea seedlings can take up P. aeruginosa DNA through their roots, but the P. aeruginosa DNA recovered by direct extraction of whole plants is partially degraded. When nuclear and nonnuclear fractions were prepared prior to DNA extraction, no P. aeruginosa DNA was found in either fraction, although both fractions contained nuclear DNA of pea. This is taken as evidence that P. aeruginosa DNA had not become sequestered in nucleoprotein of the pea nucleus, and was therefore exposed to nuclease action during preparation. 3. (3) Tobacco cells in shake cultures can take up tobacco DNA or P. aeruginosa DNA, provided that the cells are first washed and treated with pronase to eliminate DNAase secreted into the medium by the cells. Approx. 0.5% of exogenous DNA initially available was recovered in a partially degraded but nevertheless high molecular weight state from the nuclear fraction of tobacco cells. The remainder appeared to be very extensively degraded, and the breakdown products were largely found within the cells. 4. (4) In the course of this work a heavy satellite DNA of tobacco was encountered which was more rapidly labeled than general nuclear DNA.
TL;DR: With inhibitors of DNA synthesis used in the presence of ethidium bromide, it has been possible to distinguish between synthesis of informational DNA (I-DNA) and that of nuclear DNA.
Abstract: With inhibitors of DNA synthesis used in the presence of ethidium bromide, it has been possible to distinguish between synthesis of informational DNA (I-DNA) and that of nuclear DNA. Hydroxyurea depresses I-DNA synthesis preferentially but does not affect DNA transport between cell compartments. 5-Fluorodeoxyuridine and cytosine arabinoside reduce synthesis of I-DNA to a much lesser degree than that of nuclear DNA.
TL;DR: A study of variance in [ 3 H]thymidine incorporation by S nuclei sharing the same cytoplasm - using binucleate, trinucleate and multinucleates homokaryons - showed that nuclei through the peak-S period synthesized DNA at approximately similar rates as discussed by the authors.
Abstract: By means of the nuclear transfer technique for amoeba, combinations of nuclei and cytoplasma from all parts of the cell cycle were available for examining the individual roles of the nucleus and cytoplasm in nuclear DNA replication. Neither S-phase nor division sphere cytoplasm proved capable of initiating a new round of nuclear DNA synthesis in the G 2 nucleus. There was some indication that G 2 nuclei which were transferred into early prophase cells, i.e. before the formation of a regular division sphere, did incorporate more [ 3 H]thymidine than control G 2 nuclei. Positive proof of the induction of DNA synthesis in ‘immature’ nuclei was observed in only two cases. When young G 2 nuclei were transplanted into late G 2 amoebae, the addition of the donor nucleus generally resulted in the older nucleus being held in a late G 2 phase until the younger nucleus passed through its G 2 . Division of 90% of heterophasic homokaryons was synchronous, with a subsequent synchrony of DNA synthesis. A study of variance in [ 3 H]thymidine incorporation by S nuclei sharing the same cytoplasm - using binucleate, trinucleate and multinucleate homokaryons - showed that nuclei through the peak- S period synthesized DNA at approximately similar rates. The large differences in [ 3 H]thymidine incorporation by nuclei of amoebae of equal age appear due to differences in endogenous precursor pools. These would vary both with differences in food intake and with the draining of remote precursor pools for simultaneous cellular activities, particularly RNA synthesis. When sharing the same cytoplasm nuclei in peak S incorporated similar amounts of [ 3 H]thymidine. Though cytoplasm did not influence the progress of DNA replication by a nucleus, it did influence the use of exogenous [ 3 H]thymidine by the cell, and in so doing caused much of the variation observed in the labelling of nuclei during S . Nuclei sharing the same cytoplasm, and so subject to the same precursor pool changes, incorporated similar amounts of exogenous thymidine. Once DNA synthesis had been initiated it continued to completion regardless of the cytoplasm which surrounded it. Thus neither the maintenance nor termination of DNA synthesis required a special cytoplasmic state.
TL;DR: A MAJOR episode of DNA synthesis occurs during the interphase preceding meiosis1–4, and additional periods of synthesis have been detected by autoradiography during leptotene, zygotene or pachytene in newt, man and mouse.
Abstract: A MAJOR episode of DNA synthesis occurs during the interphase preceding meiosis1–4. Additional periods of synthesis have been detected by autoradiography during leptotene, zygotene or pachytene in newt5, man6 and mouse7. In Lilium and Trillium separate periods of synthesis have been demonstrated at zygotene and pachytene by 32P-phosphate labelling followed by DNA extraction8. Others have failed to detect prophase synthesis autoradiographically3,4, presumably because of the low level of label incorporation during synthesis of amounts of DNA estimated to represent 0.3–2.0% of the total nuclear DNA content5,9.
TL;DR: In this paper, it was shown that between 10% and 70% of the nuclear DNA of all higher organisms consists of repeating sequences, which comprise families of identical or similar base sequences repeated from several hundred to more than a million times.
Abstract: BETWEEN 10% and 70% of the nuclear DNA of all higher organisms consists of repeating sequences1,2 (in some organisms only 6–13 base pairs long3) which comprise families of identical or similar base sequences repeated from several hundred to more than a million times. Much of this is not transcribed4 and the most repetitive sequences are located in the centromeric heterochromatin5. If repetitive DNA occurs in all eukaryotic cells, however, it is surprising that in renaturation studies it has not been found in yeast2,6. In Saccharomyces cerevisiae,a large number of the AT base pairs of the mitochondrial DNA probably occur in poly AT sequences7,8. This may result in unusual renaturation kinetics.
TL;DR: There are significant differences in nuclear DNA amount between Eu-Sorghum species and it is suggested that the lower DNA concentration may reflect a lower proportion of heterochromatin relative to euchromatin in the wild as compared with the cultivated forms.
Abstract: There are significant differences in nuclear DNA amount between Eu-Sorghum species. The DNA variation is considerable. For example Sorghum durra has 63 per cent more DNA than Sorghum roxburghii. Increase in nuclear DNA is accompanied by increase in the mass of the nucleolus and of non-nucleolar material including the chromosomes. The ratio of DNA to non-DNA material is constant between species. The DNA concentration per unit volume at interphase in somatic nuclei and per unit of chromosome length is significantly lower in the wild species S. sudanense and S. virgatum than in the cultivated species S. caudatum, S. conspicuum, S. durra and S. roxburghii. It is suggested that the lower DNA concentration may reflect a lower proportion of heterochromatin relative to euchromatin in the wild as compared with the cultivated forms.
TL;DR: Synthesis of chloroplast and mitochondrial DNA must continue after synthesis of nuclear DNA has been virtually stopped by cycloheximide, suggesting that all unstable proteins essential for synthesis ofchloroplast DNA are made on cytoplasmic ribosomes, or all proteins required for this synthesis turn over slowly.
TL;DR: The results indicate that DNA synthesis in a high proportion of cells in the lactating gland may not represent premitotic DNA replication and suggest a partial replication of the cellular genome during early lactogenesis and suggests the significance of “gene amplification” has been discussed.
Journal Article•
TL;DR: It is suggested that bleomycin prevents cells from entering visible mitosis but does not inhibit DNA synthesis at this dosage and that DNA replication without cell cleavage probably results in a higher DNA content in a significant proportion of the cell population.
Abstract: Summary The nuclear DNA content of the VX-2 carcinoma of rabbits was measured by microspectrophotometry in 22 animals before, during, and after multiple i.m. injections of bleomycin given over a prolonged time period. Striking changes were noted in the distribution pattern of the nuclear DNA content of VX-2 carcinoma cells with higher levels of bleomycin administration. The population of stemline cells, which was dominant in the controls, decreased after the treatment, and the population of cells with twice the stemline DNA content increased. In addition, a few cells containing four times the stemline DNA content also appeared. The mitotic index decreased immediately after the initiation of bleomycin therapy and was maintained at a low level during the extended period of drug administration. These findings suggest that bleomycin prevents cells from entering visible mitosis but does not inhibit DNA synthesis at this dosage and that DNA replication without cell cleavage probably results in a higher DNA content in a significant proportion of the cell population.
TL;DR: Infection of confluent monolayer cultures of African green monkey kidney cells with simian virus 40 results in an enhanced synthesis of nuclear and mitochondrial DNA.
Abstract: Infection of confluent monolayer cultures of African green monkey kidney cells with simian virus 40 results in an enhanced synthesis of nuclear and mitochondrial DNA. This is demonstrated both by an increased rate of incorporation of [3H]thymidine into mitochondrial DNA and by detection of increased amounts of mitochondrial DNA in infected cells. With monkey BSC-1 cells, where SV40 infection does not result in a stimulation of nuclear DNA synthesis, no stimulation of mitochondrial DNA synthesis is observed. SV40 infection of mouse 3T3 cells also stimulates nuclear and mitochondrial DNA synthesis.