The Desoxyribonucleic Acid Content of Animal Cells and Its Evolutionary Significance

Abstract

The DNA (desoxyribonucleic acid) content per cell, according to some recent investigations, is a constant for the various somatic cells of an organism, and sperm cells contain one-hail this amount per ceU (1, 2). The quantity of DNA per cell is a characteristic of each organism. In this work, done independentiy by two groups of investigators, the DNA per ceLl was found by determining the quantity of DNA in a suspension containing a known number of ceUs and then dividing the total DNA by the number of cells. For sperm and erythrocytes the cells themselves were counted; for tissue cells isolated nuclei were prepared, analyzed, and counted.Knowledge concerning the DNA content per cell has been extended along two lines. On the one hand, more examples have been brought forward. In the original work, for example, the DNA contents of erythrocytes, liver ceUs, and sperm of fowl were determined and DNA determinations for cells of fowl kidney, spleen, heart, and pancreas have now been added by Davidson and his colleagues (3). These results are given in Table I. In a series of careful measurements by Davison and Osgood on human granulocytes and lymphocytes (from leukemic blood), two quite different cell types, the DNA per cell of the former was found to be 6.25 X 10 -0 rag. and that of the latter 5.84 × 10 -0 rag. (4). Our own determinations on human sperm gave 2.72 X 10 -9 mg. per cell, approximately one-half the value for the somatic cells.Another line of investigation has been to determine by a cytochemical procedure the DNA content per nucleus (5). In this procedure it is possible to make determinations on single nuclei, either as isolated cells and nuclei or in tissue sections. It has been found that the Feulgen nucleal reaction gives reproducible results and that a microphotometric observation serves as a measure of DNA content. The essential requirement in this procedure is a standard of known DNA content and heretofore none was available. A whole series of standards was provided by the work mentioned above in which DNA per nucleus was determined chemically. One set of standards consisted of nucleated * Dr. Ris' present address is:

DNA content in eurasian sturgeon species determined by flow cytometry

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A Bird's-Eye View of the C-Value Enigma: Genome Size, Cell Size, and Metabolic Rate in the Class Aves

“…throughout the class of birds'' (Gulliver 1875, p. 475), and moreover that avian ''erythrocyte size appears to be related to the general metabolic activity of the species'' (Hartman and Lessler 1963, p. 467). For more than half a century it has been known that birds have genomes smaller than those of most other vertebrates Vendrely 1949, 1950;Mandel et al 1951;Mirsky and Ris 1951), and it was similarly shown very early that ''in the nucleated red cells of vertebrates . .…”

Cytophotometric Study of Deoxyribonucleic Acid in Cortisone-Treated Rat Hepatocytes

“…It should be emphasized that explanations for the present cytophotometric observations can be advanced which do not necessarily contradict the generally accepted concept of DNA constancy (12,13). From each class of nuclei, 19 per cent of the DNA, a portion apparently not essential for cell life, has been dissociated from the chromatin under the influence of cortisone.…”