Differentiation Inducing Phosphatidyl Choline(s) from the Embryos of Rainbow Trout ( Salmo gairdneri ): Isolation and Structural Elucidation 1

Phospholipid which is able to induce the differentiation of some undifferentiated tumour cells was isolated from the rainbow trout ( Salmo gairdneri ) embryos. As HPLC gave only one peak, the phospholipid seemed to be completely purified. However, the spectra of SIMS and FD‐MS have shown that it was a mixture of two molecular species. By the chemical and enzymic studies their structures were determined as C 16:0 /C 22:6 ‐and C 18:1 /C 22:6 ‐phosphatidyl cholines. The isolated and structurally elucidated phosphatidyl cholines induce haemoglobin synthesis in murine erythroleukemia cells and a rapid decrease in alkaline phosphatase activity in teratocarcinoma cells. Some phosphatidyl cholines which are commercially available have shown no or conspicuously low activities. Recently we isolated another differentiation‐inducing substance(s), which proved to be diglyceride(s) containing the completely same fatty acids as those in the above mentioned phosphatidyl cholines, that is, C 16:0 /C 22:6 ‐and C 18:1 /C 22:6 . These results suggest that the lipids containing C 22:6 fatty acid or this fatty acid itself might play an important part in the differentiation and development.