scholarly journals RIBOSOMAL DNA AMOUNTS IN PISUM SATIVUM

Genetics ◽  
1975 ◽  
Vol 81 (3) ◽  
pp. 485-492
Author(s):  
C A Cullis ◽  
D Roy Davies
Keyword(s):  
Pisum Sativum ◽  
Ribosomal Dna ◽  
Dna Content ◽  
Leaf Size ◽  
Rrna Genes ◽  
Root Tips ◽  
The One ◽  
Cotyledon Cells ◽  
Dna Amounts

ABSTRACT Different varieties of peas have different proportions of rDNA in their genomes; there is no obvious correlation between the proportions and seed or leaf size. The rDNA proportions in root tips, seedlings, leaves and in the cotyledon cells of high DNA content, were compared in four varieties. In three, there was no difference between tissues; the fourth showed an amplification of rRNA genes in the cells of high DNA content of the seed cotyledon, and also in the cells of young but not of older leaves. The fourth variety was the one that had the lowest proportion of rDNA of all those examined. Studies of the tissues of hybrids between genotypes with "low" and "high" proportions of rDNA showed that heterozygotes had the "high" value, showing again the occurrence of an amplification phenomenon.

scholarly journals Chromosome Number, Ploidy Level, and Nuclear DNA Content in 23 Species of Echeveria (Crassulaceae)

Genes ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1950
Author(s):  
Guadalupe Palomino ◽  
Javier Martínez-Ramón ◽  
Verónica Cepeda-Cornejo ◽  
Miriam Ladd-Otero ◽  
Patricia Romero ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Chromosome Number ◽  
Ploidy Level ◽  
Dna Content ◽  
Chromosome Numbers ◽  
Nuclear Dna ◽  
Nuclear Dna Content ◽  
Root Tips ◽  
Ploidy Levels ◽  
Dna Amounts

Echeveria is a polyploid genus with a wide diversity of species and morphologies. The number of species registered for Echeveria is approximately 170; many of them are native to Mexico. This genus is of special interest in cytogenetic research because it has a variety of chromosome numbers and ploidy levels. Additionally, there are no studies concerning nuclear DNA content and the extent of endopolyploidy. This work aims to investigate the cytogenetic characteristics of 23 species of Echeveria collected in 9 states of Mexico, analyzing 2n chromosome numbers, ploidy level, nuclear DNA content, and endopolyploidy levels. Chromosome numbers were obtained from root tips. DNA content was obtained from the leaf parenchyma, which was processed according to the two-step protocol with Otto solutions and propidium iodide as fluorochrome, and then analyzed by flow cytometry. From the 23 species of Echeveria analyzed, 16 species lacked previous reports of 2n chromosome numbers. The 2n chromosome numbers found and analyzed in this research for Echeveria species ranged from 24 to 270. The range of 2C nuclear DNA amounts ranged from 1.26 pg in E. catorce to 7.70 pg in E. roseiflora, while the 1C values were 616 Mbp and 753 Mbp, respectively, for the same species. However, differences in the level of endopolyploidy nuclei were found, corresponding to 4 endocycles (8C, 16C, 32C and 64C) in E. olivacea, E. catorce, E. juarezensis and E. perezcalixii. In contrast, E. longiflora presented 3 endocycles (8C, 16C and 32C) and E. roseiflora presented 2 endocycles (8C and 16C). It has been suggested that polyploidization and diploidization processes, together with the presence of endopolyploidy, allowed Echeveria species to adapt and colonize new adverse environments.

Severely distorted Feulgen-DNA amounts in Pinus (Coniferophytina) after nonadditive fixations as a result of meristematic self-tanning with vacuole contents

1986 ◽  
Vol 28 (3) ◽  
pp. 409-415 ◽  
Author(s):  
Johann Greilhuber
Keyword(s):  
Acetic Acid ◽  
Allium Cepa ◽  
Dna Content ◽  
Nuclear Dna ◽  
Large Fraction ◽  
Internal Standard ◽  
Feulgen Reaction ◽  
Root Tips ◽  
Meristematic Tissue ◽  
Dna Amounts

Highly divergent nuclear DNA amounts were obtained in Pinus mugo and Pinus cembra when meristematic tissue from root tips was fixed either with neutral formaldehyde or various nonadditive agents as methanol – acetic acid, ethanol – acetic acid, alcohols alone, Carnoy's fluid, acetone, or was directly hydrolyzed with 5 M HCl. After formaldehyde fixation, the 1C values in P. mugo and P. cembra amount to 20.16 and 24.16 pg, respectively, when calibrated against Allium cepa as internal standard, but 1C values after application of nonadditive fixatives are strongly reduced to 25–41% of the former values. This phenomenon is explained by the observation that in Pinus a large fraction of the meristematic cells contains a considerably large vacuome, whose content (probably condensed tannins) becomes immobilized after formaldehyde fixation and further on does not interfere with the Feulgen reaction, whereas after nonadditive fixations the vacuole contents extravasate and strongly tan the whole meristem and especially the nuclei. The Feulgen reaction is impaired. The tint and absorbance spectra are different in pine and Allium cepa nuclei. Pinus Feulgen-DNA values obtained after fixations other than formaldehyde must be regarded as highly distorted from the true genomic DNA content. Self-tanning as a source of methodical error in DNA content determinations by cytochemical techniques may be widespread because of the frequent occurrence of tannins in the plant kingdom.Key words: Feulgen reaction, DNA contents, tannins, Pinus, conifers.

scholarly journals Methylocella Species Are Facultatively Methanotrophic

2005 ◽  
Vol 187 (13) ◽  
pp. 4665-4670 ◽  
Author(s):  
Svetlana N. Dedysh ◽  
Claudia Knief ◽  
Peter F. Dunfield
Keyword(s):  
Methane Oxidation ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Methanotrophic Bacteria ◽  
Soluble Methane Monooxygenase ◽  
Cell Counts ◽  
Carbon Compounds ◽  
Methane Fluxes ◽  
The One ◽  
Pcr Targeting

ABSTRACT All aerobic methanotrophic bacteria described to date are unable to grow on substrates containing carbon-carbon bonds. Here we demonstrate that members of the recently discovered genus Methylocella are an exception to this. These bacteria are able to use as their sole energy source the one-carbon compounds methane and methanol, as well as the multicarbon compounds acetate, pyruvate, succinate, malate, and ethanol. To conclusively verify facultative growth, acetate and methane were used as model substrates in growth experiments with the type strain Methylocella silvestris BL2. Quantitative real-time PCR targeting the mmoX gene, which encodes a subunit of soluble methane monooxygenase, showed that copies of this gene increased in parallel with cell counts during growth on either acetate or methane as the sole substrate. This verified that cells possessing the genetic basis of methane oxidation grew on acetate as well as methane. Cloning of 16S rRNA genes and fluorescence in situ hybridization with strain-specific and genus-specific oligonucleotide probes detected no contaminants in cultures. The growth rate and carbon conversion efficiency were higher on acetate than on methane, and when both substrates were provided in excess, acetate was preferably used and methane oxidation was shut down. Our data demonstrate that not all methanotrophic bacteria are limited to growing on one-carbon compounds. This could have major implications for understanding the factors controlling methane fluxes in the environment.

Preparation of pea (Pisum sativum L.) chromosome and nucleus suspensions from single root tips

1996 ◽  
Vol 92 (6) ◽  
pp. 744-751 ◽  
Author(s):  
G. Gualberti ◽  
J. Doležel ◽  
J. Macas ◽  
S. Lucretti
Keyword(s):  
Pisum Sativum ◽  
Root Tips ◽  
Single Root ◽  
Pisum Sativum L

Excision and replication of extrachromosomal DNA of pea (Pisum sativum)

1983 ◽  
Vol 3 (2) ◽  
pp. 172-181
Author(s):  
J Van't Hof ◽  
C A Bjerknes ◽  
N C Delihas
Keyword(s):  
Cell Cycle ◽  
Pisum Sativum ◽  
S Phase ◽  
Velocity Sedimentation ◽  
Extrachromosomal Dna ◽  
Chromosomal Dna ◽  
Root Tips ◽  
Dividing Cells ◽  
G2 Phase ◽  
Pea Roots

Experiments with cultured pea roots were conducted to determine (i) whether extrachromosomal DNA was produced by cells in the late S phase or in the G2 phase of the cell cycle, (ii) whether the maturation of nascent DNA replicated by these cells achieved chromosomal size, (iii) when extrachromosomal DNA was removed from the chromosomal duplex, and (iv) the replication of nascent chains by the extrachromosomal DNA after its release from the chromosomal duplex. Autoradiography and cytophotometry of cells of carbohydrate-starved root tips revealed that extrachromosomal DNA was produced by a small fraction of cells accumulated in the late S phase after they had replicated about 80% of their DNA. Velocity sedimentation of nascent chromosomal DNA in alkaline sucrose gradients indicated that the DNA of cells in the late S phase failed to achieve chromosomal size. After reaching sizes of 70 X 10(6) to 140 X 10(6) daltons, some of the nascent chromosomal molecules were broken, presumably releasing extrachromosomal DNA several hours later. Sedimentation of selectively extracted extrachromosomal DNA either from dividing cells or from those in the late S phase showed that it replicated two nascent chains, one of 3 X 10(6) daltons and another of 7 X 10(6) daltons. Larger molecules of extrachromosomal DNA were detectable after cells were labeled for 24 h. These two observations were compatible with the idea that the extrachromosomal DNA was first replicated as an integral part of the chromosomal duplex, was cut from the duplex, and then, once free of the chromosome, replicated two smaller chains of 3 X 10(6) and 7 X 10(6) daltons.

Initiation and termination of DNA replication in human rRNA genes

1993 ◽  
Vol 13 (10) ◽  
pp. 6600-6613
Author(s):  
R D Little ◽  
T H Platt ◽  
C L Schildkraut
Keyword(s):  
Dna Replication ◽  
Ribosomal Dna ◽  
Regulatory Elements ◽  
Transcription Unit ◽  
Replication Initiation ◽  
Rrna Genes ◽  
Rrna Gene ◽  
Replication Forks ◽  
Nontranscribed Spacer ◽  
Dna Repeat

We have used the multicopy human rRNA genes as a model system to study replication initiation and termination in mammalian chromosomes. Enrichment for replicating molecules was achieved by isolating S-phase enriched populations of cells by centrifugal elutriation, purification of DNA associated with the nuclear matrix, and a chromatographic procedure that enriches for molecules containing single-stranded regions, a characteristic of replication forks. Two-dimensional agarose gel electrophoresis techniques were used to demonstrate that replication appears to initiate at multiple sites throughout most of the 31-kb nontranscribed spacer (NTS) of human ribosomal DNA but not within the 13-kb transcription unit or adjacent regulatory elements. Although initiation events were detected throughout the majority of the NTS, some regions may initiate more frequently than others. Termination of replication, the convergence of opposing replication forks, was found throughout the ribosomal DNA repeat units, and, in some repeats, specifically at the junction of the 3' end of the transcription unit and the NTS. This site-specific termination of replication is the result of pausing of replication forks near the sites of transcription termination. The naturally occurring multicopy rRNA gene family offers a unique system to study mammalian DNA replication without the use of chemical synchronization agents.

Preparation of pea (Pisum sativum? L.) chromosome and nucleus suspensions from single root tips

1996 ◽  
Vol 92 (6) ◽  
pp. 744-751 ◽  
Author(s):  
G. Gualberti ◽  
J. Dolezel ◽  
J. Macas ◽  
J. Macas ◽  
S. Lucretti ◽  
...  
Keyword(s):  
Pisum Sativum ◽  
Root Tips ◽  
Single Root ◽  
Pisum Sativum L

Replication of the rRNA and legumin genes in synchronized root cells of pea (Pisum sativum): evidence for transient EcoR I sites in replicating rRNA genes

1987 ◽  
Vol 8 (2) ◽  
pp. 133-143 ◽  
Author(s):  
J. Van't Hof ◽  
P. Hernandez ◽  
C. A. Bjerknes ◽  
E. K. Kraszewska ◽  
S. S. Lamm
Keyword(s):  
Pisum Sativum ◽  
Rrna Genes ◽  
Root Cells
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