The DNA content of sperm of Drosophila melanogaster

Rasch, Ellen M.; Barr, Helen; Rasch, Robert W.

doi:10.1007/bf00326379

Cited by 223 publications

(70 citation statements)

References 44 publications

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“…Although the human 2C-value of 7.0 pg was set rather arbitrarily, it provided a solid platform to calibrate a range of secondary standards. The 2C-value of 2.5 pg determined by Tiersch et al (53) for chicken was in a perfect agreement with the value determined by Rasch et al (54) and other authors cited by them and independently confirmed the 2C-value of 7.0 pg for man. This 2C-value is commonly assumed today as a consensual 2C-value of the human (17,(55)(56)(57) and was used to calibrate a set of recommended plant DNA reference standards (58, Table 2).…”

Section: Human As a Primary Reference Standardsupporting

confidence: 89%

Nuclear genome size: Are we getting closer?

2010

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Correct information on genome size is important in many areas of research. For a long time, scientists have been struggling to understand the reason for the huge variation in eukaryotic genome size and its biological significance. More recently, the knowledge on genome size has become important to structure genome sequencing projects as their scale and cost depend on genome size. Despite the fact that the first estimates of genome size in eukaryotes were made more than 50 years ago, we are still not quite sure about the exact genome size in practically all animal and plant species. Moreover, different estimates continue to be published for the same species. These discrepancies compromise data comparison and interpretation and point to methodological problems, which include standardization. This article assesses the current state of DNA reference standards for flow cytometry and the issues related to their calibration. ' 2010 International Society for Advancement of CytometryKey terms cytometric techniques; reference standards; genome sequencing; conversion factor; nuclear DNA content; C-value MOST of the genetic information in eukaryotes is localized in the cell nucleus and numerous attempts have been made to determine the quantity of nuclear DNA, especially after various lines of evidence associated DNA with genes (1). It soon became clear that the amount of DNA per nucleus is relatively constant in somatic cells of a given species and that sperm cells have approximately half the DNA amount found for somatic cells (2,3). These experiments provided independent data to support the hereditary role of DNA and marked the beginning of numerous fruitful lines of research and applications, many of them still important today, all relying on the ability to determine DNA amounts in cell nuclei.The early determinations were made colorimetrically on DNA extracted from a known number of cells although the presence of cells in different cell cycle phases could compromise the accuracy of these estimates. The colorimetric approach made identification of subpopulations of cells with different DNA amounts impossible. However, cytometric methods suitable for measurement of absorbance of light in individual nuclei (either using UV light with non-stained nuclei and/or monochromatic visible light with nuclei stained by the Feulgen reaction) were already available during the 1940s and were used to discover the presence of cells with different classes of DNA amounts. Such cells were observed in a variety of animal tissues and were associated with polyploidy and polyteny (4,5). The presence of nuclei with 2, 4, 8, 16, or 32 times the haploid value was described in plant tissues by Swift (6) who introduced the ''C'' terminology to classify nuclear DNA amounts. In this terminology, DNA classes are labeled as C, 2C, 4C, 8C, etc. to characterize DNA amounts of nuclei by multiples of the DNA amount in a complete chromosome set in a non-replicated haploid nucleus, which has the class C DNA amount.At the beginning of the 1950s, biochem...

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Section: Human As a Primary Reference Standardsupporting

confidence: 89%

Nuclear genome size: Are we getting closer?

2010

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“…(Laird 1971(Laird , 1973Rasch et al 1971;Kavenoff and Zimm 1973;Mulligan and Rasch 1980;Celniker et al 2002;Hoskins et al 2002;Bennett et al 2003). Two best-fit curves (one for PI and another for DAPI) were obtained, which then were used to convert 2C measurements into megabase values.…”

Section: Methodsmentioning

confidence: 99%

Analysis of Drosophila Species Genome Size and Satellite DNA Content Reveals Significant Differences Among Strains as Well as Between Species

et al. 2007

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The size of eukaryotic genomes can vary by several orders of magnitude, yet genome size does not correlate with the number of genes nor with the size or complexity of the organism. Although ''whole''-genome sequences, such as those now available for 12 Drosophila species, provide information about euchromatic DNA content, they cannot give an accurate estimate of genome sizes that include heterochromatin or repetitive DNA content. Moreover, genome sequences typically represent only one strain or isolate of a single species that does not reflect intraspecies variation. To more accurately estimate whole-genome DNA content and compare these estimates to newly assembled genomes, we used flow cytometry to measure the 2C genome values, relative to Drosophila melanogaster. We estimated genome sizes for the 12 sequenced Drosophila species as well as 91 different strains of 38 species of Drosophilidae. Significant differences in intra-and interspecific 2C genome values exist within the Drosophilidae. Furthermore, by measuring polyploid 16C ovarian follicle cell underreplication we estimated the amount of satellite DNA in each of these species. We found a strong correlation between genome size and amount of satellite underreplication. Addition and loss of heterochromatin satellite repeat elements appear to have made major contributions to the large differences in genome size observed in the Drosophilidae.

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“…The latter was chosen simply because it is the average absorbancy of chicken erythrocyte nuclei under our experimental conditions. For conversion to picograms of DNA, the coded data are simply reconverted to standardised data (percentage of chicken standard) then multiplied by 25, the generally accepted DNA value of diploid chicken erythrocyte nuclei (Rasch et al, 1971). The coded data were subjected to descriptive statistical analysis which included generation of sample means, variances, ranges, coefficients of variation, and the g1 and g2 indices of distribution normality.…”

Section: And Methodsmentioning

confidence: 99%

Genome size variation among north american minnows (Cyprinidae). I. distribution of the variation in five species

1985

Heredity

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Genome sizes (nuclear DNA contents) were examined spectrophotometrically from ten individuals of each of five species of North American cyprinid fishes (minnows). The distributions of DNA values both within and between the five species were essentially continuous and normal. Differences between individuals within populations were significant and contributed to approximately 16 per cent of the total variation. Variation between individuals within species ranged from 47-135 per cent and averaged ca. 7•4 per cent. Variation between species ranged from O-95 per cent and the averaie difference between any species pair was Ca. 46 per cent. Statistical analyses showed that the methodology used was sufficient to detect significant differences in genome size as small as 2-3 per cent. Consideration of these data lead to the following tentative conclusions: (i) changes in genome size in cyprinids appear small in amount, frequent in occurrence, to involve both gains and losses of DNA, and to be cumulative and independent in effect; (ii) differences within and between cyprinid taxa are likely the result of accumulations of small changes in DNA quantity; and (iii) the primary focus of quantitative DNA variation in cyprinids is between individuals within populations. The extent of DNA quantity variation which occurs within species would appear to preclude any direct relationship between genome size variation and many of the organismal parameters (including speciation) which differentiate the five species. In short, the data suggest that a significant fraction of the cyprinid genome, perhaps more than 10 per cent, is free to vary quantitatively without phenotypic constraint or biological consequence. This fraction is considerably larger than that theoretically needed for the structural gene component. INTRODUCTIONA long-standing problem in evolutionary genetics regards the quantitative variation in genome size or nuclear DNA content (the C-value) among eukaryotic organisms. Abundant data are now accumulated which show that large, often spectacular differences in genome size commonly occur between even closely related taxa, and that increases in genome size are not necessarily associated with evolutionary advancement (Bachmann et a!., 1972;Rees and Jones, 1972; Hinegardner, 1976;Price, 1976). Early suggestions (Kauffman, 1971) were that the variation was related to either the number of genes in an organism, its organismal complexity, or both. The general concensus now, however, is that there are no significant correlations between genome size (the C-value) and organismal or genetic complexity (Cavalier-Smith, 1978). This is called the C-value paradox. Other pertinent findings which have emerged are that: (i) increasing organismal specialization in body form and design may often be associated with The underlying causes of genome size variation are not well understood. Much of the data has been interpreted as supporting the idea that the variation has an adaptive basis and is strongly 298 J R. GOLD AND H. JAMES PRICE influenced...

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The DNA content of sperm of Drosophila melanogaster

Cited by 223 publications

References 44 publications

Nuclear genome size: Are we getting closer?

Nuclear genome size: Are we getting closer?

Analysis of Drosophila Species Genome Size and Satellite DNA Content Reveals Significant Differences Among Strains as Well as Between Species

Genome size variation among north american minnows (Cyprinidae). I. distribution of the variation in five species

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