Scanning electron microscopic study of chylomicrons incubated with lipoprotein lipase
Scanning electron microscopic study of chylomicrons incubated with lipoprotein lipase
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脂蛋白脂肪酶孵育乳糜微粒的扫描电子显微镜研究
DOI：
10.1002/ar.1091840402
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发表时间：
1976
期刊：
影响因子：
--
通讯作者：
R. Scow
中科院分区：
文献类型：
--
作者：
E. Blanchette‐Mackie;R. Scow
利用大鼠乳糜微粒与纯化的牛乳脂蛋白脂肪酶在pH 8.1下孵育20分钟，通过扫描电镜观察脂解对乳糜微粒结构的影响。由于添加到培养基中的白蛋白量有限，一些游离脂肪酸和脂解形成的部分甘油酯积聚在乳糜微粒中。在扫描电子显微镜下，pH值为7.4的OsO4固定的脂解乳糜微粒表面呈多凹痕不规则球形，而pH值为5.5的固定乳糜微粒以及两种pH固定的对照乳糜微粒表面呈光滑球形。用透射电子显微镜观察OsO4固定标本的切片，发现固定在pH 7.4的脂解乳糜微粒的核心在外围含有许多圆形的电子发光区，从而解释了上面观察到的凹痕表面，而其他标本的核心表面是圆形和光滑的。这些发现证实了先前的报道，即当培养基中的白蛋白有限时，在脂解过程中乳糜微粒中形成水空间，并且当pH为5.5的样品制备用于显微镜时，水空间消失。扫描电镜样品的薄片显示，金钯涂层直接沉积在pH 7.4固定的脂解乳糜微粒脂质核的凹陷表面。我们得出结论，在样品制备过程中，真空脱水使脂解乳糜微粒的水空间外壁破裂，从而使空间内部暴露于金钯涂层和扫描电子显微镜下观察。
The effects of lipolysis on the structure of chylomicrons were studied with the scanning electron microscope using rat chylomicrons incubated with purified bovine milk lipoprotein lipase for 20 minutes at pH 8.1. Since the amount of albumin added to the medium was limited, some of the free fatty acids and partial glycerides formed by lipolysis accumulated in the chylomicrons. Lipolyzed chylomicrons fixed with OsO4 at pH 7.4 appeared in scanning electron micrographs as spheres with multiply indented irregular surfaces, while those fixed at pH 5.5, as well as control chylomicrons fixed at both pHs, appeared as spheres with smooth surfaces. Sections of OsO4‐fixed specimens, viewed with the transmission electron microscope, showed that the core of lipolyzed chylomicrons fixed at pH 7.4 contained numerous circular electron‐lucent areas at the periphery, thus accounting for the indented surfaces observed above, while the core surfaces of the other specimens were circular and smooth. These findings confirm an earlier report that aqueous spaces form in chylomicrons during lipolysis when albumin in the medium is limited, and that the aqueous spaces disappear when specimens are prepared at pH 5.5 for microscopy. Thin sections of specimens that had been prepared for scanning electron microscopy showed that the gold‐palladium coating was deposited directly on the indented surface of the lipid core of lipolyzed chylomicrons fixed at pH 7.4. It is concluded that vacuum dehydration during specimen preparation ruptures the outer wall of the aqueous spaces in lipolyzed chylomicrons and thereby exposes the interior of the spaces to gold‐palladium coating and viewing with the scanning electron microscope.