cAMP-induced changes in the cytosolic free Ca2+ concentration in Dictyostelium discoideum are light sensitive
cAMP-induced changes in the cytosolic free Ca2+ concentration in Dictyostelium discoideum are light sensitive
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DOI：
10.1016/s0143-4160(97)90090-7
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发表时间：
1997-07-01
期刊：
影响因子：
4
通讯作者：
Schlatterer, C
中科院分区：
文献类型：
--
作者：
Sonnemann, J;Knoll, G;Schlatterer, C
用化学诱导剂cAMP攻击盘基盘阿米巴，分析其胞内游离钙浓度([Ca~(2+)](I))。用数字成像法测定钙指示剂Fura-2-葡聚糖对单个细胞内[Ca~(2+)](I)的影响。低浓度cAMP(0.1-1微米)的整体刺激可引起整体一过性[Ca~(2+)](I)升高。当细胞受到高剂量的光照射时，这种增加被消除。然而，在短短几分钟的恢复期后，细胞再次显示出正常的反应。[Ca~(2+)]~(2+)升高的抑制作用依赖于光照波长。我们比较了340、380、405、450或490 nm在规定强度下照射细胞所需的恢复期。405 nm的光有明显的作用，340 nm单独或与380 nm联合使用也有效，但影响较小，450 nm和490 nm都不能抑制[Ca~(2+)](I)的增加，即使在很高的照度下也是如此。这种波长依赖关系与在黑暗中生长的阿米巴的吸收光谱相匹配，这种吸收光谱含有一种似乎负责单个细胞趋光性的感光色素。与光照培养的细胞相比，黑暗中生长的细胞表现出对cAMP诱导的瞬间[Ca~(2+)](I)对光的敏感性增加。根据这些数据，我们得出结论，趋光信号可以在[Ca~(2+)](I)变化的水平上干扰趋化信号。
The cytosolic free calcium concentration ([Ca2+](i)) of the social amoeba Dictyostelium discoideum was analyzed after challenge with the chemoattractant cAMP. [Ca2+](i) was measured by digital imaging in single cells loaded with the Ca2+ indicator Fura-2-dextran. Global stimulation with low concentrations of cAMP (0.1-1 mu M) led to a global transient [Ca2+](i) increase. This increase was abolished when cells were illuminated with high doses of light. However, after a short recovery period of several minutes, the cells again displayed the normal response. Inhibition of the [Ca2+](i) elevation depended on the wavelength of illumination light. We compared the required recovery period of cells irradiated with either 340, 380, 405, 450 or 490 nm at defined intensities. Light of 405 nm had a pronounced effect; 340 nm alone or in combination with 380 nm was also effective, but to a lesser extent, whereas neither 450 nm nor 490 nm inhibited the [Ca2+](i) increase, even at very high irradiance. The wavelength dependence matched the absorption spectrum of amoebae grown in darkness that contain a photopigment which seems to be responsible for phototaxis of single cells. Cells grown in darkness exhibited an increased sensitivity of the cAMP-induced [Ca2+](i) transient towards light compared to light-grown cells. From these data we conclude that phototactic signaling could interfere with chemotactic signaling at the level of [Ca2+](i) changes.