Abstract
DNA values lower than the lowest value of the vertebrates were found for a urochordate and a cephalochordate. On the assumption that the genomes of surviving primitive chordata reflect the status of the genomes possessed by ancient organisms from which vertebrates eventually evolved, it is suggested that vertebrates started from an organism with a very small amount of DNA. Two cyclostomes, on the other hand, showed relatively high DNA values suggesting that the increase in DNA both by regional duplication of chromosomal segments and by polyploidization began to occur before vertebrates developed the jaw. The DNA values relative to the human female leucocyte value were: Ciona intestinalis: 6%; Amphioxus lanceolatus: 17%; Lampetra planeri: 38%; and Eptatretus stoutii: 78%.
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In Northwood, this work was supported by the British Empire Cancer Campaign for Research, and in Duarte by a grant (CA-05138) from the National Cancer Institute, U.S.Public Health Service, and in part by a research fund established in honor of General James H. Doolittle.
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Atkin, N.B., Ohno, S. DNA values of four primitive chordates. Chromosoma 23, 10–13 (1967). https://doi.org/10.1007/BF00293308
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DOI: https://doi.org/10.1007/BF00293308