Phospholipid and nucleic acid gradients in the developing amphibian embryo.
Rana pipiens embryos at the end of the blastula stage were dissociated and the cell suspension was separated into presumptive ectoderm, mesoderm, light endoderm, and heavy endoderm cells by a discontinuous density gradient centrifugation technique. The isolated germ layers were analyzed for total lipid, lipid phosphorus, plasmalogen, RNA, and DNA. Per gram dry weight, DNA showed a threefold decrease from ectoderm to heavy endoderm. On the same basis, the RNA content of the mesoderm was 34 per cent higher than that of ectoderm, and 320 and 570 per cent higher than that of light and heavy endoderm, respectively. In addition to the RNA and DNA gradients, there were at least two superimposed lipid gradients: a neutral lipid gradient decreasing from ectoderm to endoderm, and a total phospholipid gradient increasing from ectoderm to endoderm. In contrast to total phospholipid, a specific phospholipid class, ethanolamine plasmalogen, decreased from ectoderm to endoderm. The total lipid content per gram dry weight was the same in all the germ layers. Total phospholipids were analyzed quantitatively by thin layer chromatography. Phosphatidylcholine, phosphatidylethanolamine, sphingomyelin, and inositol phospholipid constituted 34, 13, 12, and 34 per cent, respectively, of the total lipid phosphorus. The phospholipid composition was different in each germ layer. The possible role of specific lipids in embryonic induction and differentiation is discussed.
D000818:Animals; D001001:Anura; D002498:Centrifugation; D055598:Chemical Phenomena; D002621:Chemistry; D002623:Chemistry Techniques, Analytical; D004247:DNA; D004475:Ectoderm; D004625:Embryo, Nonmammalian; D004707:Endoderm; D066298:In Vitro Techniques; D008648:Mesoderm; D010743:Phospholipids; D012313:RNA
D010743:Phospholipids; D012313:RNA; D004247:DNA
J Mol Biol. 1961 Jun;3:318-56
13718526
Can J Res. 1949 Jun;Sect E 27(3):159-63
18151260
J Biol Chem. 1956 Mar;219(1):39-47
13295254
J Biol Chem. 1955 Nov;217(1):199-204
13271383
Proc Natl Acad Sci U S A. 1951 Oct;37(10):650-65
16578397
Nature. 1956 Sep 15;178(4533):582-3
13369467
J Biol Chem. 1957 Nov;229(1):131-8
13491566
J Biol Chem. 1951 Aug;191(2):833-41
14861228
Hoppe Seylers Z Physiol Chem. 1954;298(3-5):110-20
14353437
Cancer Res. 1960 Nov;20:1508-13
13702819
Fed Proc. 1963 Jan-Feb;22:8-18
13961251
J Biol Chem. 1964 Mar;239:740-2
14154447
J Embryol Exp Morphol. 1958 Mar;6(1):117-23
13539274
J Biol Chem. 1958 Oct;233(4):814-7
13587498
Dev Biol. 1962 Dec;5:412-34
14015922