Sanders E J, Chokka P
Department of Physiology, University of Alberta, Edmonton, Canada.
J Cell Sci. 1987 Apr;87 ( Pt 3):389-98. doi: 10.1242/jcs.87.3.389.
Chick embryos in culture were treated with the secretion-inhibiting ionophore monensin at the gastrulation stage of development. After treatment for 5 h at a concentration of 10(-5) M the embryos showed a drastic reduction in the tissue space between the upper and lower epithelia, and reduced spreading of the mesoderm cells that occupied this space. The basement membrane, to which many mesoderm cells are normally attached, showed varying degrees of disruption, which permitted blebbing of the overlying epithelium. Intracellularly, the treatment caused extensive vacuolization in all tissues. These results were consistent with the effects expected by removal of hyaluronic acid from the extracellular space, and this was confirmed by demonstrating a sharp reduction in glucosamine incorporation in this region. Examination of the effects of monensin on isolated mesoderm cells in culture using interference reflection microscopy indicated that the spreading of these cells was reduced independently of the changes in the extracellular matrix of the embryo. That this was probably due to the inhibition of cell surface fibronectin secretion was shown by demonstrating severe changes in the distribution of this glycoprotein using the immunofluorescent technique. It is concluded that the effects of monensin on this intact, developing system are due primarily to the disruption of hyaluronic acid secretion, but that disrupted fibronectin synthesis contributes to the reduced spreading of mesoderm cells.
在发育的原肠胚形成阶段，用分泌抑制离子载体莫能菌素处理培养中的鸡胚。在10⁻⁵M浓度下处理5小时后，胚胎上下上皮之间的组织间隙显著减小，占据该间隙的中胚层细胞的铺展也减少。许多中胚层细胞通常附着的基底膜显示出不同程度的破坏，这使得覆盖其上的上皮细胞出现泡状形成。在细胞内，这种处理导致所有组织中广泛的空泡化。这些结果与从细胞外空间去除透明质酸所预期的效果一致，并且通过证明该区域中氨基葡萄糖掺入的急剧减少得到了证实。使用干涉反射显微镜检查莫能菌素对培养中的分离中胚层细胞的影响表明，这些细胞的铺展减少，与胚胎细胞外基质的变化无关。使用免疫荧光技术证明这种糖蛋白分布的严重变化表明，这可能是由于细胞表面纤连蛋白分泌受到抑制。得出的结论是，莫能菌素对这个完整的发育系统的影响主要是由于透明质酸分泌的破坏，但纤连蛋白合成的破坏也导致了中胚层细胞铺展的减少。
