. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. DNA IN HYBRID EMBRYOS 31 the early development at least 50 per cent, viz. the DNA in the male chromosomes, be synthesized from rather low-molecular substances. The constancy of DNA during segmentation should not, therefore, be taken to demonstrate that no DNA synthesis occurs. Rather it indicates that DNA is synthesized at the expense of preformed desoxyribosides, and that no total synthesis of DNA occurs. RESULTS The results are shown in Figure 1. The DNA content at the beginning of development is ± //,g (standa
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. DNA IN HYBRID EMBRYOS 31 the early development at least 50 per cent, viz. the DNA in the male chromosomes, be synthesized from rather low-molecular substances. The constancy of DNA during segmentation should not, therefore, be taken to demonstrate that no DNA synthesis occurs. Rather it indicates that DNA is synthesized at the expense of preformed desoxyribosides, and that no total synthesis of DNA occurs. RESULTS The results are shown in Figure 1. The DNA content at the beginning of development is ± //,g (standard deviation: ± /*g). This value is calculated as the average of five determinations (only three of these are shown Time, in- too 150 2OO 30 HubruLs : \pi-f?. £ x f^sulv. cf Controls: l\.pLi>. o o Tamp: 15" C OM-. 8 9 10 18 12 H 15 16 H Staqe- of ControLs ( Skiim FIGURE 1. Desoxyribonucleic acid content of normal and hybrid embryos at various stages of development. in the figure) on eggs from 2 to 4 hours after fertilization (2-8 cells). The content is the same in hybrids (; ) and in controls (; ; ). According to Sze (1953) the DNA content of a diploid nucleus in R. pipicns is X 10~6 ^g. The reserve would thus correspond to about 6000 Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Marine Biological Laboratory (Woods Hole, Mass. ); Marine Biological Laboratory (Woods Hole, Mass. ). Annual report 1907/08-1952; Lillie, Frank Rattray, 1870-1947; Moore, Carl Richard, 1892-; Redfield, Alfred Clarence, 1890-1983. Woods Hole, Mass. : Marine Biological Laboratory
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