Changes in the Distribution of Phosphorus in the Developing Grasshopper (Melanoplus differentialis) Embryo

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Abstract
The distr. of various P compounds was analyzed in the grasshopper egg, embryo and cell constituents, i.e., nucleus and cytoplasm. Lipid P (LP) in the egg declines rapidly in the prediapause period and remains at a fairly constant level in the diapause and postdiapause phases. Acid soluble P (ASP), on the other hand, shows only a slight decrease in earlier development but undergoes a rapid fall in the later stages. Both ribonucleic acid phosphorus (RNAP) and desoxyribonucleic acid phosphorus (DNAP) increase during development. The increase of DNAP parallels growth, while the increase of RNAP is slightly irregular. It appears that DNAP is closely related to RNAP in their syntheses. The precursors and the immediate phosphorus pool for the synthesis of nucleic acids have been discussed and the mechanism of the syntheses has been diagrammatically postulated. DNAP is almost entirely confined within the nucleus while RNAP is chiefly located in the cytoplasm. In the cytoplasm, ASP and RNAP seem to be interrelated while in the nucleus, LP and DNAP are interrelated. During diapause, the amount of LP in the nucleus is much lower than in the active developmental phases. Evidence suggests that LP may play a part in mitotic activity. The number of nuclei of an embryo in different developmental stages has been counted and the DNAP content has been measured. Each nucleus has, on an average, 1.27 x 10-6 [um]g. DNAP or 12.8 x 10-6 [um]g. DNA.