Pasquini J M, Najle R, Soto E F
Brain Res. 1979 Aug 3;171(2):295-306. doi: 10.1016/0006-8993(79)90334-2.
Subfractions of fraction A, which floats on top on 0.8 M sucrose in the classical density gradient used for the isolation of brain subcellular fractions (A1 corresponding in adult rats to myelin and A2 which corresponds to the myelin-like fraction), were studied in comparison to other brain subcellular fractions in 5 day old rats and at different stages of development, up to 60 days of age. Variations in the enzymatic activity of acetylcholinesterase, non-specific cholinesterase and 2',3'-Cyclic nucleotide phosphohydrolase, changes in lipid and protein composition and turnover of phosphatidyl choline were investigated. Results indicate that fractions A1 and A2 obtained prior to the beginning of myelination could be composed of fragments of the oligodendroglial cell plasma membranes, and that both fractions undergo substantial changes in chemical composition, enzymatic activity and in turnover of phosphatidyl choline during maturation. In vivo experiments at short times, using radioactive choline as a precursor of phosphatidylcholine suggest that membrane fragments isolated in fraction A2 are precursors of those isolated in fraction A1 at all ages.
在用于分离脑亚细胞组分的经典密度梯度中漂浮在0.8M蔗糖之上的组分A的亚组分（成年大鼠中A1对应于髓磷脂，A2对应于类髓磷脂组分），与5日龄大鼠及直至60日龄不同发育阶段的其他脑亚细胞组分进行了比较研究。研究了乙酰胆碱酯酶、非特异性胆碱酯酶和2',3'-环核苷酸磷酸水解酶的酶活性变化、脂质和蛋白质组成的变化以及磷脂酰胆碱的周转情况。结果表明，在髓鞘形成开始之前获得的组分A1和A2可能由少突胶质细胞质膜的片段组成，并且在成熟过程中，这两个组分在化学成分、酶活性和磷脂酰胆碱周转方面都发生了实质性变化。在短时间内使用放射性胆碱作为磷脂酰胆碱前体的体内实验表明，在所有年龄段，在组分A2中分离的膜片段都是在组分A1中分离的膜片段的前体。
