Delaye M, Danford-Kaplan M E, Clark J I, Krop B, Gulik-Krzywicki T, Tardieu A
Exp Eye Res. 1987 May;44(5):601-16. doi: 10.1016/s0014-4835(87)80132-x.
Opacification was induced in calf lens cytoplasmic extracts by addition of calcium. The sample turbidity was shown to increase with calcium molarity, incubation time and temperature and to decrease with the protein cytoplasmic concentration. Although this turbidity was enhanced when membrane fragments were left over in the cytoplasmic extracts, it did show up in the absence of any detectable vesicular fragment. Scattering techniques (X-ray and light) showed that the calcium-induced opacification is linked to enhanced light scattering, which results from the formation of additional scatterers, a few tens of nm in diameter. Additional structures were indeed visualized by freeze-fracture electron microscopy (FFEM): they appear as molecular clusters with diameters ranging from 20 to 90 nm, made of densely packed particles, with heterogeneous sizes. The turbidity expected from these clusters, as well as the expected variation of turbidity with cytoplasmic concentration, was calculated to be in agreement with the measurements. When compared with cold cataract, these results illustrate that similar opacities may result from completely different biophysical mechanisms.
通过添加钙诱导小牛晶状体细胞质提取物发生浑浊。结果表明，样品浊度随钙摩尔浓度、孵育时间和温度的增加而增加，随细胞质蛋白浓度的降低而降低。尽管当细胞质提取物中残留膜碎片时这种浊度会增强，但在没有任何可检测到的囊泡碎片的情况下也会出现这种情况。散射技术（X射线和光）表明，钙诱导的浑浊与光散射增强有关，这是由直径几十纳米的额外散射体的形成引起的。通过冷冻断裂电子显微镜（FFEM）确实观察到了额外的结构：它们表现为直径范围从20到90纳米的分子簇，由紧密堆积的颗粒组成，颗粒大小不一。计算得出这些簇预期的浊度以及浊度随细胞质浓度的预期变化与测量结果一致。与冷冻性白内障相比，这些结果表明，完全不同的生物物理机制可能导致相似的浑浊。
