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DNA Content of Monotremes

Abstract

INTEREST has recently been focused on the DNA content of the different classes of vertebrates. Although the number and size of chromosomes in placental mammals vary considerably, biochemical determinations have shown that the DNA content is relatively constant1. Atkin et al.2, using the microdensitometer method, found that the placental mammals constitute a fairly uniform group with regard to the total genetic content, as do birds which have a DNA content about half (44–59 per cent) that of eutherians. Reptiles, however, fall into two distinct categories2: the order Squamata has a DNA value 60–67 per cent that of placental mammals, while Crocodylia and Chelonia have 80–89 per cent. These percentages agree with those obtained by Ohno3, who measured chromosomal areas of colchicinized metaphases.

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BICK, Y., JACKSON, W. DNA Content of Monotremes. Nature 215, 192–193 (1967). https://doi.org/10.1038/215192a0

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