Martelly I, Molla A, Thomasset M, Le Moigne A
Cell Differ. 1983 Sep;13(1):25-34. doi: 10.1016/0045-6039(83)90073-8.
Regeneration does not occur when planarians are grown in Ca2+-free medium. The possible effect of calcium upon DNA synthesis was therefore studied using cultured planarian cells and regenerating planarian fragments. In the cultures, DNA synthesis was Ca2+-dependent and required a minimum of 10(-6) M Ca2+ in the medium. It was gradually decreased in cells grown in Ca2+-free medium. Addition of Ca2+ to these cultures raised DNA synthesis. The time lag between addition of Ca2+ and stimulation of DNA synthesis varied with culture age. The triggering effect of Ca2+ was amplified by ionophore A 23187. A calcium binding protein, ram testis calmodulin, intensified the stimulatory effect of calcium, but EGTA blocked this effect. In the presence of trifluoperazine (TFP), DNA synthesis was not stimulated by Ca2+. This inhibition by TFP was overcome by adding calmodulin to the medium. Ca2+ therefore triggered DNA synthesis in vitro, and this role might have been potentiated by calmodulin. In vivo, DNA synthesis was shown to be dependent on the Ca2+ concentration in the medium in which intact or regenerating planarians were grown. In 12-h regenerates, the Ca2+ concentration in the medium was no longer critical. Total calcium content decreased just after sectioning until completion of healing (at 6 h) and then rose significantly to a peak at 12 h which coincided with the first peak of DNA synthesis. The calmodulin content gradually diminished during the first 6 h after sectioning. After a transient rise at 12 h, calmodulin content further decreased until 48 h. The results demonstrate the crucial role of Ca2+ in triggering DNA synthesis in planarian cells in vitro and in regenerating fragments. Calmodulin, whose concentration is very low in planarians compared to vertebrates, might help to induce the first peak of DNA synthesis at 12 h after sectioning, but is probably not the main Ca2+-binding protein involved in the regeneration process.
涡虫在无钙培养基中培养时不会发生再生。因此，使用培养的涡虫细胞和再生的涡虫片段研究了钙对DNA合成的可能影响。在培养物中，DNA合成依赖于Ca2+，培养基中至少需要10(-6) M的Ca2+。在无钙培养基中生长的细胞中，DNA合成逐渐减少。向这些培养物中添加Ca2+可提高DNA合成。添加Ca2+与刺激DNA合成之间的时间间隔随培养年龄而变化。离子载体A 23187可增强Ca2+的触发作用。一种钙结合蛋白，公羊睾丸钙调蛋白，增强了钙的刺激作用，但EGTA可阻断这种作用。在三氟拉嗪（TFP）存在的情况下，Ca2+不会刺激DNA合成。向培养基中添加钙调蛋白可克服TFP的这种抑制作用。因此，Ca2+在体外触发DNA合成，钙调蛋白可能增强了这一作用。在体内，DNA合成被证明依赖于完整或再生涡虫生长的培养基中的Ca2+浓度。在12小时的再生过程中，培养基中的Ca2+浓度不再关键。总钙含量在切片后立即下降，直到愈合完成（6小时），然后在12小时显著上升至峰值，这与DNA合成的第一个峰值一致。钙调蛋白含量在切片后的前6小时逐渐减少。在12小时短暂上升后，钙调蛋白含量进一步下降直至48小时。结果表明Ca2+在体外触发涡虫细胞和再生片段中的DNA合成中起关键作用。与脊椎动物相比，涡虫中钙调蛋白的浓度非常低，它可能有助于在切片后12小时诱导DNA合成的第一个峰值，但可能不是参与再生过程的主要Ca2+结合蛋白。
