Translocation of 14Carbon in Tobacco following Assimilation of 14Carbon Dioxide by a Single Leaf

¹⁴CO₂ was assimilated by single leaves (presentation leaves)of tobacco plants for periods of 2–3 hours. The plantswere then kept in air in continuous light and the redistributionof radioactivity determined at various times up to 96 hours.There was a complete turnover of sucrose in the presentationleaf in about 24 hours without change in amount. Starch turnedover more slowly and simultaneously increased in amount. 20–30per cent. of the radioactivity appeared to be irreversibly incorporatedinto the presentation leaf. Of the material exported from thepresentation leaf some 3 per cent. reached the upper leavesand stem apex. Import into leaves above the presentation leafwas completed in about 6 hours. No activity appeared in leavesbelow the presentation leaf, therefore the balance of the exportedactivity was retained in the stem and roots. The distribution of radioactivity in the leaves followed a well-definedpattern determined by the vascular interconnexions. Radioautographs of stem sections provided some information concerningdistribution of radioactivity in the stem.     

Comparison of Amino-acid Sequences of Hypothalamic Peptide,Brain-specific Histone and Myelin Basic Protein

SEVERAL studies have described the basic proteins of porcine central nervous tissue. Shome and Saffran¹ have isolated and purified a large peptide (or small protein) of molecular weight about 14,000 from acetone-dried hog hypothalamic powder. Sixteen of the approximately twenty-six tryptic digest fragments of this protein have been sequenced. The protein has no pressor or ACTH-releasing activity. Tomasi-and Kornguth² purified and partially characterized a basic protein from pig brain and, on the basis of fluorescent antibody studies, they concluded that this protein is a brain-specific histone, found in neurone nuclei (or nucleoli) of several animals^3–5.