D1, a nonhistone chromosomal protein rich in both basic and acidic amino acids, has been localized at a limited number of specific loci in polytene chromosomes of Drosophila melanogaster. H2B, a nucleosomal histone, and H1, a nonnucleosomal histone, are both found throughout most chromosomal regions.
The Philadelphia chromosome, characteristic of chronic granulocytic leukemia, contained 61+/-1 percent as much DNA as a number 21 (or 22) chromosome from which it is believed to be derived. The remaining 39 percent represents 0.5 percent of a diploid chromosome complement, approximately 2 x 10(7) nucleotide pairs; the method used was not sensitive enough to detect whether it had been translocated to other chromosomes.
inducing materials of the endosperm exhibit identical behavior. On the other hand, gibberellins are the only substances which cause normal growth in the maize dwarfs and bolting and flowering in cold-requiring and long-day plants. In view of these facts, it seems safe to conclude that the substances in the Echinocystis endosperm which promote growth in the maize dwarfs and which induce bolting and flowering in Hyoscyamus and Samolus are identical. This means that the gibberellinlike materials which exist in seed plants are capable of regulating bolting and flower formation, and it may be assumed that they play a crucial part in the normal regulation of these processes in the plant and may be involved in their control by low temperature and day length. The details of the function of these materials in bolting and flower formation as well as their chemical nature must await further work on the part of plant physiologists and chemists.Summary.-Application of endosperm of E. macrocarpa (Cucurbitaceae) caused prompt bolting and flowering in biennial H. niger and in the long-day plant S. parviflorus grown under non-inductive conditions. The effect can be attributed to the gibberellin-like materials which are present in this endosperm. It is concluded that gibberellin-like materials participate in the processes of flower formation in plants and their control by low temperature and photoperiod.
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