. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 410 JOHN RUNNSTROM AND BORJE MARKMAN Figure 13 refers again to the elaborate experiment of Table I. An and Veg indicate here the centers of production of the animalizing and vegetalizing agents, and the wedges their concentration gradients towards the opposite poles. These agents, or at least their precursors, are certainly present before the fertilization, as indicated also by the data presented by Giudice and Horstadius (1965). A later replenishment mediated by genes is, however, probable. Figure 13 shows also how the agen
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 410 JOHN RUNNSTROM AND BORJE MARKMAN Figure 13 refers again to the elaborate experiment of Table I. An and Veg indicate here the centers of production of the animalizing and vegetalizing agents, and the wedges their concentration gradients towards the opposite poles. These agents, or at least their precursors, are certainly present before the fertilization, as indicated also by the data presented by Giudice and Horstadius (1965). A later replenishment mediated by genes is, however, probable. Figure 13 shows also how the agents may have a different influence on equal genoms located at two different levels in the double gradient system. The ratio of concentrations of animalizing and vegetalizing agents at the two levels is different and this is supposed to cause the activation or repression of different genes or operons (Jacob and Monod, 1963). An (Gen) (§5) Veg Act v A. Li Act' (55) Veg An (§en) (Gen) Veg V A -act Li, Li act FIGURE 13. Diagrammatic representation of the state of chemo-differentiation in embryos exposed to sea water (C0), to sea water with actinomysin D (Cact), to sea water with lithium (Li0) and to sea water with lithium and actinomycin ('). Each part of the diagram referring to one test (C0, etc.) is divided into two parallel diagrams. The one to the left represents the gradients of animalizing and vegetalizing agents and their action on equal genoms at different levels during the exposure to the added substances. Actinomycin D blocks the transcription of information from the genom and removes thus, at least partially, the effect of the animalizing and vegetalizing agents. To the right, the extents of the animal and vegetal pathways are indicated in the embryos after transfer to normal medium. See, further, text. To the right in each of the schemes Co-Liact in Figure 13, the results of the assumed interactions are symbolized. The wedges indicate here the relation between a
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
