Average Amount Of DNA Research Articles

Pathogenic and Saprophytic Growth Rates of Fusarium oxysporum f. sp. vasinfectum Interact to Affect Variation in Inoculum Density and Interannual Infection Risk.

Fusarium wilt of cotton caused by the soilborne fungal pathogen Fusarium oxysporum f. sp. vasinfectum race 4 (FOV4) is a contemporary epidemic affecting cotton production in Far West Texas. The spatial distribution of soilborne FOV4 can be heterogeneous at small scales, and the factors that lead to this heterogeneity require investigation. Hypothetical causes include dissemination of spores through soils and variable saprophytic growth of the fungus. In the field, FOV4 DNA was quantified from soil during and after the cotton-growing season, and though the average amounts of DNA were not different between these time points, the variances of DNA across space were significantly different. Variability was higher when pathogenic growth of the fungus was expected owing to the presence of live cotton plants and lower when saprophytic growth was expected after cropping. In sterile-environment growth chamber experiments, the abundance of organic matter influenced the fungal vegetative growth rate and maximum amount as measured through quantitative PCR and the timing of the fungus' increasing its rate of spore production as measured through dilution plating. To investigate movement of spores in soils, spore mobility in experimental columns was quantified. Soil composition and organic matter abundance affected spore mobility, indicating that the timing of spore production relative to the availability of growth resources will affect the spatial spread of FOV4 and suggesting that soil properties affect the retention of conidia. The spatial spread of FOV4 through soil varies temporally and is affected by the shift between pathogenic and saprophytic growth modes of the fungus.

Quantification of DNA of Fusarium culmorum and Trichothecene Genotypes 3ADON and NIV in the Grain of Winter Wheat.

Fusarium head blight (FHB) is a wheat disease caused by fungi of the genus Fusarium. The aim of the study was to find relationships between the weather conditions in the experimental years and the locations and the amount of F. culmorum DNA and trichothecene genotypes, as well as the proportions between them. A three-year field experiment (2017, 2018 and 2019) was established in two locations (Poznań, Radzików). The DNA of F. culmorum was detected in all grain samples in an average amount of 20,124 pg per 1 μg of wheat DNA. The average amount of DNA from the 3ADON genotype was 4879 pg/μg and the amount of DNA from the NIV genotype was 3330 pg/μg. Weather conditions strongly affected the amount of DNA of F. culmorum and trichothecene genotypes detected in the grain. In the three experimental years, a high variability was observed in the coefficients of correlation between DNA concentrations and the FHB index, FDK, ergosterol and the corresponding toxins. There were significant correlations between disease incidence, fungal biomass (quantified as the total amount of fungal DNA or DNA trichothecene genotypes) and toxins (DON, 3AcDON and NIV) concentrations. The 3ADON trichothecene genotype dominated over the NIV genotype (ratio 1.5); however, this varied greatly depending on environmental conditions.

Polyploidy does not control all: Lineage‐specific average chromosome length constrains genome size evolution in ferns

AbstractRecent studies investigating the evolution of genome size diversity in ferns have shown that they have a distinctive genome profile compared with other land plants. Ferns are typically characterized by possessing medium‐sized genomes, although a few lineages have evolved very large genomes. Ferns are different from other vascular plant lineages as they are the only group to show evidence for a correlation between genome size and chromosome number. In this study, we aim to explore whether the evolution of fern genome sizes is not only shaped by chromosome number changes arising from polyploidy but also by constraints on the average amount of DNA per chromosome. We selected the genus Asplenium L. as a model genus to study the question because of the unique combination of a highly conserved base chromosome number and a high frequency of polyploidy. New genome size data for Asplenium taxa were combined with existing data and analyzed within a phylogenetic framework. Genome size varied substantially between diploid species, resulting in overlapping genome sizes among diploid and tetraploid spleenworts. The observed additive pattern indicates the absence of genome downsizing following polyploidy. The genome size of diploids varied non‐randomly and we found evidence for clade‐specific trends towards larger or smaller genomes. The 578‐fold range of fern genome sizes have arisen not only from repeated cycles of polyploidy but also through clade‐specific constraints governing accumulation and/or elimination of DNA.

Correlation of the rate of protein synthesis and the third power of the RNA : protein ratio in Escherichia coli and Mycobacterium tuberculosis.

In order to further understand the different physiological states of the tubercle bacillus, a frame of reference was sought by first correlating the macromolecular compositions of Escherichia coli with specific growth rates and also with the rates of protein synthesis. Data for DNA : protein : RNA were converted to the average amounts of DNA [m(DNA(av))], protein [m(p(av))] and RNA [m(RNA(av))] per cell. The specific growth rate micro was found to be directly proportional to m(RNA(av))/m(p(av)). The specific protein synthesis rate per average cell [omega(p(av))] was shown to be directly proportional to the third power of the ratio m(RNA(av))/m(p(av)) which reflects the ribosome concentration. The equations derived were shown apply to both E. coli ( micro =1.73 h(-1)) and Mycobacterium bovis BCG ( micro =0.029 h(-1)).

Physical characteristics of the genome of the phytopathogenic fungus Puccinia graminis.

The physical characteristics of the genome of Puccinia graminis f. sp. tritici, the wheat stem rust fungus, were determined by reassociation kinetics. The results indicate that the haploid genome contains 67 Mb and consists of three classes of DNA sequences: (1) 64% unique; (2) 30% repetitive; and (3) 4% foldback. The repetitive sequences have a total complexity of 390 kb and are repeated an average of 52 times. The base composition was 45.3% G+C based on an analysis of the DNA melting temperature. The average amount of DNA per ungerminated urediniospore by diphenylamine assay, corrected for losses during extraction, was 435 fg. This was three times the expected value (147 fg) for dikaryotic spores with nuclei in the G1 phase of the cell cycle, an indication that the spores were in G2.

Direct procedure for the determination of the number of replication forks and the reinitiation fraction in bacteria.

A direct method for calculating the average number of replication forks per chromosome in an exponentially growing bacterial culture and the fraction of reinitiation after an inductive treatment of the initiation step is presented. This method has allowed the development of REPLICON, a computer program designed for the resolution of the algorithm and simulation of the bacterial chromosome replication. Using REPLICON the following parameters can be obtained: average number of replication forks per chromosome, time required for the complete replication cycle, average amount of DNA per nucleotide, gene frequency of any chromosomal locus and reinitiation fraction. The use of this analysis also permits the determination of the uni- or bidirectionality of replication.

Analysis of DNA size, content and cell cycle in leaves of Napier grass (Pennisetum purpureum Schum.)

Mesophyll cell nuclei isolated from leaves of Pennisetum purpureum were analysed by flow cytometry to determine the nuclear DNA content and the percentage of cells in different phases of the cell cycle. Samples taken from base, middle and tip regions of leaves 2 to 8 (leaf 1, which was adjacent to the meristem, was too small to sample) showed no significant differences in the amount of DNA per G1 nucleus due to either age or position. The average amount of DNA per G1 nucleus was 5.78 pg. Although the majority of cells for each sample were in G1, samples taken from older leaves had higher percentages of cells in G2 and S phases. More specifically, base and middle regions of older leaves had a higher percentage of cells in G2 than all three positions in younger leaves. Electrophoretic analysis of nuclear DNA from leaves 2 to 7 showed no evidence of degradation or difference in fragment size for any sample or position. This study was compared to previous work on the relationship between leaf age and embryogenic competence in Pennisetum purpureum. The results suggest that changes in the cell cycle, and/or a loss or fragmentation of the nuclear DNA, are not responsible for loss of embryogenic competence in mature leaf tissue.

Adipose tissue of Drosophila melanogaster: VII. Distribution of nuclear DNA amounts along the anterior–posterior axis in the larval fat body

The DNA content of fat body nuclei was measured cytophotometrically as a function of position along an anterior-posterior (A-P) axis of the tissue throughout larval development. There was a dramatic 55-fold increase in the average amount of DNA per nucleus during the first 3 days of this period, but there was no further increase during the final day. However, the rate of increase had regional specificity. The amount of DNA per nucleus correlated significantly with its position along the A-P axis of the tissue: nuclei in a posterior direction contain gradually increasing amounts of DNA. There was up to a seven-fold difference between the smallest anterior and largest posterior nucleus. In addition, for three of the ages studied there was a subgradient in the posterior region with a slope that was considerably steeper than that of the overall tissue gradient. The tissue has three characteristic morphological regions, anterior, medial, and posterior, which can be recognized early in development and which are maintained throughout the larval period. The distribution of nuclear DNA classes determined for cells in each region for the final 2 days of larval life became fixed before the final day of development. The significance of the DNA gradient in terms of a protein storage gradient is discussed.

On an Actinocephalid Gregarine (Apicomplexa: Sporozoea) Odonaticola diplacodi sp. nov., from Odonate Insect, Diplacodes trivialis ( Rambur)

Summary In “polyploid” clones of Amoeba proteus with the nuclear DNA content increased two- and four-fold as compared with the normal level, the average amount of DNA sometimes appears to be reduced after prolonged cultivation. This reduction is due to the appearance of cells with a two-and, accordingly, a four-fold decreased DNA content. The proportion of such cells in “polyploid” clones grows with time. Nevertheless, “polyploid” cultures may be maintained infinitely via supporting selection. Gradual substitution of “polyploid” cells by normal ones occurs also in artificially mixed amoeban cultures. The presence of aberrant (quadrilobate) nuclei in “polyploid” clones allows the suggestion that multipolar mitosis may be the mechanism of “depolyploidization”. A hypothesis is advanced that the processes of spontaneous “polyploidization” and “depolyploidization” in A. proteus take place in nature as well and may be a source of genetical variation in these agamous organisms.

DNA and RNA contents in relation to cell and seed weight in Pisum sativum

The rates of increase in DNA, RNA and fresh weight were determined for a series of stages of cotyledon development in three varieties of Pisum sativum. The average amounts of DNA in the cells of the cotyledon (up to 64C) were directly proportional to the average weights of the cells for the whole of the period of development in the case of two-seeded varieties, and for the first part of the developmental period for the large-seeded variety. Increases in RNA values for all three varieties were proportional to cell weight in the early stages but at later stages RNA values decreased. A hypothesis for the regulation of DNA and RNA synthesis by the cell volume is proposed.

Variability of DNA content in individual cells of Bacillus.

THE average content of DNA in Bacillus spores is unaffected by the growth medium and is constant for each species1. Within the Bacillus group, however, the average amount of DNA per spore varies from species to species1. A cell of B. cereus contains on average twice as much DNA as the spore and during sporulation this DNA is divided equally between the spore and the sporangium2. Estimates3–5 of genome size vary from 1.3 × 109 to 10 × 109 daltons and the number of genomes per cell from 2 to 44–8. Some of these variations may be associated with differences within the cells rather than differences of methodolqgy; spores within a population vary not only in size and shape, but also in their content of stainable chromatin9. Moreover, in ‘Renografm’ density gradients10, spores band within a range of densities. If spores are taken from a narrow part of this range, regrown and rebanded, the original pattern of dispersal occurs, suggesting that spores in the same population normally show variation in density as well as in size (A. I. Aronson, personal communication).

Ratios of protein fractions to DNA and electrophoretic studies of histones of diploid and polyploid nuclei of rat liver

Diploid and polyploid nuclei have been isolated from the livers of 3–4-month-old rats. The extent of contamination of each fraction with the other fraction being probably not above 10%, as shown by microscopic counting and analyses of DNA per nucleus. (The average amount of DNA per diploid nucleus was 5.5 pg and per polyploid nucleus was 12.8 pg.) No differences could be established in the ratios of the globulin fraction, total histone, or residual proteins to DNA for the two classes of nuclei. The disc-gel electrophoretic patterns and analyses of histones for amino acids were also the same for diploid and polyploid nuclei.

DNA, RNA, and Protein in the Pea Shoot Apex in Relation to Leaf Initiation

The average amounts of DNA, RNA, and protein per cell measured histochemically in each region of the shoot apical meristem remained unchanged during the course of a plastochron and during the early development of the leaf primordium. The average content of DNA, RNA, and protein per cell was the same in all regions of the shoot apical meristem.

QUANTITATIVE CHANGES IN NUCLEAR DNA ACCOMPANYING POSTGERMINATION EMBRYONIC DEVELOPMENT IN VANDA (ORCHIDACEAE)

Nuclear DNA was measured cytophotometrically in sections and isolated nuclei of the developing embryo of Vanda. The data were interpreted in terms of developmental stage and spatial relationships of the nuclei within the embryo. An equal amount of DNA was found in all meristematic nuclei regardless of the developmental stage of the embryo and was taken as the 2C value. Most of the nuclei in the parenchymatous region fell into the discrete DNA classes, 2C, 4C, and 8C. A significant number, however, had DNA contents above 8C but could not be grouped into classes based on a whole‐number multiple of 2C. Nuclear size was found to vary in direct proportion to DNA content through 8C. Above 8C, correlation between nuclear size and DNA content was poor. The amount of DNA in the nuclei of the parenchymatous region was shown to increase in direct proportion to the distance of the nucleus from the meristem. The average amount of DNA in parenchymal nuclei above 8C was found to increase with the developmental stage of the embryo. Mechanisms which might account for the observed changes in DNA per nucleus are discussed.

Effect of acriflavin on the kinetoplast of Leishmania tarentolae. Mode of action and physiological correlates of the loss of kinetoplast DNA.

The loss of kinetoplast DNA in Leishmania tarentolae, which occurs in the presence of low concentrations of acriflavin, was found to be a result of selective inhibition of replication of this DNA. Nuclear DNA synthesis was relatively unaffected and cell and kinetoplast division proceeded normally for several generations. An approximately equal distribution of parental kinetoplast DNA between daughter kinetoplasts resulted in a decrease in the average amount of DNA per kinetoplast. The final disappearance of the stainable kinetoplast DNA occurred at a cell division in which all the remaining visible kinetoplast DNA was retained by one of the daughter cells. The selective inhibition of kinetoplast DNA synthesis was caused by a selective localization of acriflavin in the kinetoplast. The apparent intracellular localization of dye and the extent of uptake at a low dye concentration could be manipulated, respectively, by varying the hemin (or protoporphyrin IX) concentration in the medium and by adding red blood cell extract (or hemoglobin). Hemin and protoporphyrin IX were found to form a complex with acriflavin. During growth in acriflavin, cells exhibited an increasing impairment of colony-forming ability and rate of respiration. No change in the electrophoretic pattern of total cell soluble proteins was apparent. The data fit the working hypothesis that the loss of kinetoplast DNA leads to a respiratory defect which then leads to a decrease in biosynthetic reactions and eventual cell death. A possible use of the selective localization of acriflavin in the kinetoplast to photooxidize selectively the kinetoplast DNA is suggested.

The content of deoxyribonucleic acid in individual polytene chromosomes of Chironomus tentans.

The DNA content was measured in individual polytene chromosomes of <i>Chironomus tentans</i> belonging to the two last classes of replication. The following results were obtained: (1) The DNA contents of the chromosomes of the higher size class were about twice that of the lower class, which indicates that most or all of the chromatids carry out one replication between these two stages. (2) The DNA contents were found to be correlated to chromosome length, and the average amount of DNA per band was similar in the four chromosome pairs. (3) The probable DNA value per chromatid set was determined, from which the average DNA value per chromomere could be estimated to 10<sup>-16</sup> g. This value corresponds to about 10<sup>5</sup> base pairs, suggesting either that the bands represent operational units of great complexity or that a large part of DNA is non-functional in an informational sense.

DNA in the heart of male and female house-flies of different ages

1. 1. The amount of deoxyribonucleic acid was determined in the heart and the associated tissues of adult Musca domestica L. 2. 2. The DNA analyses were performed by a microbiological method using Lactobacillus acidophilus ATCC 11506 and by the Burton modification of the Dische diphenylamine reaction. 3. 3. The average amount of DNA was found to be 0·367 μg/100 μg fresh tissues in the males, and 0·384 μg/100 μg fresh tissue in the females. These values were also expressed on a per heart and dry weight basis. 4. 4. The quantity of DNA in the hearts of the males and females of the same age group or of different age groups is similar. 5. 5. If DNA is considered an index to cell number, the cell number remains approximately constant for insects of different ages regardless of sex.

DNA CONTENT AND AREA OF SEX CHROMATIN IN SUBJECTS WITH STRUCTURAL AND NUMERICAL ABERRATIONS OF THE X CHROMOSOME.

Sex chromatin deoxyribonucleic acid (SC/DNA) content (determined by Feulgen-photometry) was higher in cultured cell nuclei derived from five women with presumptive iso-chromosomes for the long arm of the X than from five normal women. The mean SC/DNA values from subjects with deleted long arm or short arm iso-chromosome X; deletion of the short arm of X and from lymph node cultures of a subject with a ring X were significantly lower than the control values. SC/DNA from subjects with XY/XXY, XXXY and XXXXY sex chromosome constitutions did not differ from control values. In oral mucosa nuclei the mean SC/DNA and sex chromatin area from the subjects with structurally abnormal X’s also showed a correlation between X chromosome size and SC/DNA or SC/area but in this technically less suitable tissue variability was greater and the differences not statistically significant. These findings indicate that: 1. Only one X chromosome forms sex chromatin. 2. When a structural abnormality of the X is present it is always the abnormal one which becomes positively heteropycnotic. 3. It is probably all, or at least the major portion of the X which forms sex chromatin. 4. The multiple sex chromatin bodies formed in cells with supernumerary X’s contain average amounts of DNA. 5. Visual impression of sex chromatin “size” (staining intensity and area integrated) can be confirmed objectively.

Role of the thyroid gland in the control of polyploid cell formation in the rat liver.

The relationship of the thyroid gland to the control of polyploid cell formation in the rat liver was investigated in immature and in sexually mature male rats. The measurement of nuclear size and the counting of binucleated cells served as measures of polyploidy, and the presence of a polyploid DNA content was verified in one experiment by the chemical determination of the average amount of DNA per nucleus. In immature animals (50 and 68 g body weight), thyroidectomy interrupted body and liver growth, prevented the progressive accumulation of new polyploid nuclei and caused a pronounced reduction of the absolute and the relative numbers of polyploid nuclei present at the time of gland extirpation. These results were observed at postoperative intervals ranging up to 147 days. Thyroid lack also prevented the formation of binucleated cells from mononucleated diploid cells, but those already present were not reduced in numbers. Thyroidectomy in sexually mature animals (180 g body weight) prevented the accumu...

Nucleic acid content and concentration in root cells of higher plants

The absolute amounts and concentrations of RNA and DNA per cell in root apices (0–2 mm) of eleven species of higher plants were measured. There was a 57-fold variation between species in the average amount of DNA per cell and an 80-fold variation in the average amount of DNA per chromosome. There was only a sevenfold variation in the average amount of RNA per cell. There was a twofold variation in the concentration of RNA per cell and a sixfold variation in the concentration of DNA per nucleus. As the RNA content per cell increased, the RNA concentration decreased, but as the DNA content per nucleus increased, the DNA concentration also increased. The largest cells and nuclei, the highest amounts of RNA and DNA per cell and the highest concentrations of DNA in the nuclei were found in the monocotyledons studied. The highest concentrations of RNA per cell, however, were found in the dicotyledons. Measurements were also made on segments 2–4, 4–6 and 6–8 mm from the root apices of six of the species. The progress of cell expansion from the first to the fourth segments was accompanied, in five species, by increases in the average amounts of both RNA and DNA per cell. In the sixth species, the amount of RNA per cell increased but the amount of DNA decreased slightly. The increase in the amount of RNA per cell, which varied from about 50 to 70 per cent, exceeded the increase in the amount of DNA per cell in several species. The concentration of RNA per cell fell markedly during cess growth in all species. The concentration of DNA, however, remained constant in most of the nuclei, but fell in a few nuclei situated in the vascular and outer cortical tissues.