软体动物胚胎中质膜脂质侧向流动性的区域差异。

Regional differences in the lateral mobility of plasma membrane lipids in a molluscan embryo.

作者信息

Speksnijder J E, Dohmen M R, Tertoolen L G, de Laat S W

出版信息

Dev Biol. 1985 Jul;110(1):207-16. doi: 10.1016/0012-1606(85)90077-6.

Abstract

Regional and temporal differences in plasma membrane lipid mobility have been analyzed during the first three cleavage cycles of the embryo of the polar-lobe-forming mollusc Nassarius reticulatus by the fluorescence photobleaching recovery (FPR) method, using 1,1'-ditetradecyl 3,3,3',3'-tetramethylindocarbocyanine iodide (C14diI) as a fluorescent lipid probe. During this period of development the lateral diffusion coefficient of membrane lipids is consistently greater in the vegetal polar lobe area as compared to the animal plasma membrane area (on average 30%), demonstrating the existence of an animal-vegetal polarity in plasma membrane properties. At third cleavage, the differences between animal and vegetal plasma membrane region become even more pronounced; in the four animal micromeres the diffusion coefficient (D) and mobile fraction (MF) are 2.9 +/- 0.2 X 10(-9) cm2/sec and 51 +/- 2%, respectively, while in the four vegetal macromeres D = 5.0 +/- 0.3 X 10(-9) cm2/sec and MF = 78 +/- 2%. Superimposed upon the observed animal-vegetal polarity, the lateral diffusion in the polar lobe membrane area shows a cell-cycle-dependent modulation. The highest mean values for D are reached during the S phase (ranging from 7.0 to 7.8 X 10(-9) cm2/sec in the three cycles measured), while at the end of G2 phase and during early mitosis mean values for D have decreased significantly (ranging from 5.0 to 5.9 X 10(-9) cm2/sec). Diffusion rates in the animal membranes of the embryo are constant during the three successive cell cycles (D = 4.3-5.0 X 10(-9) cm2/sec), except for a peak at the S phase of the first cell cycle (D = 6.0 X 10(-9) cm2/sec). These results are discussed in relation with previously observed ultrastructural heterogeneities in the Nassarius egg plasma membrane. It is speculated that the observed animal-vegetal polarity in the organization of the egg membrane might play an important role in the process of cell diversification during early development.

摘要

利用1,1'-二肉豆蔻基-3,3,3',3'-四甲基吲哚羰花青碘化物（C14diI）作为荧光脂质探针，通过荧光漂白恢复（FPR）方法，分析了形成极叶的软体动物网状织纹螺胚胎前三个卵裂周期中质膜脂质流动性的区域和时间差异。在这一发育阶段，与动物质膜区域相比，植物极叶区域质膜脂质的侧向扩散系数始终更大（平均大30%），这表明质膜特性中存在动物 - 植物极性。在第三次卵裂时，动物和植物质膜区域之间的差异变得更加明显；在四个动物小分裂球中，扩散系数（D）和可移动部分（MF）分别为2.9±0.2×10⁻⁹ cm²/秒和51±2%，而在四个植物大分裂球中，D = 5.0±0.3×10⁻⁹ cm²/秒，MF = 78±2%。叠加在观察到的动物 - 植物极性之上，极叶膜区域的侧向扩散表现出细胞周期依赖性调节。在S期达到D的最高平均值（在所测量的三个周期中，范围为7.0至7.8×10⁻⁹ cm²/秒），而在G2期结束时和有丝分裂早期，D的平均值显著下降（范围为5.0至5.9×10⁻⁹ cm²/秒）。胚胎动物膜中的扩散速率在连续三个细胞周期中保持恒定（D = 4.3 - 5.0×10⁻⁹ cm²/秒），除了在第一个细胞周期的S期出现一个峰值（D = 6.0×10⁻⁹ cm²/秒）。结合之前在织纹螺卵质膜中观察到的超微结构异质性对这些结果进行了讨论。推测在卵膜组织中观察到的动物 - 植物极性可能在早期发育过程中的细胞分化过程中起重要作用。