The terrestrial ciliated protozoan Colpoda cucullus inhabits soil. When the habitat conditions become unfavorable, the vegetative cells of C. cucullus quickly transform into resting cysts. C. cucullus culture is established in our laboratory, and encystment is routinely induced by the addition of Ca²⁺ to overpopulated vegetative cells. However, an increase in Ca²⁺ concentration and overpopulation of vegetative cells do not always occur in natural. We investigated the effect of temperature and found that cyst formation was induced by a rapid increase of 5 °C within 2 min but not by a decrease. Moreover, an increase in intracellular Ca²⁺ concentrations is essential, but Ca²⁺ inflow does not necessarily occur during encystment. Ca²⁺ image analysis showed that Ca²⁺ is stored in vesicular structures and released into the cytoplasm within 60 s after temperature stimulation. Multiple signaling pathways are activated after the release of Ca²⁺ from vesicles, and cAMP is a candidate second messenger with a crucial role in the process of temperature-induced encystment. Further studies are needed to clarify the mechanism underlying the sensing of temperature and release of Ca²⁺ from vesicles.

陆生纤毛原生动物Colpoda cucullus栖息于土壤中。当栖息地条件变得不利时，C。cucullus的营养细胞会迅速转化为静止的囊肿。C. cucullus培养已在我们的实验室中建立，并且通过向过度繁殖的营养细胞中添加Ca ²⁺来常规诱导包囊。但是，Ca ²⁺浓度的增加和营养细胞的过剩并不总是自然发生的。我们调查了温度的影响，发现囊肿形成是由2分钟内5°C的快速升高引起的，而不是由降低引起的。此外，必须增加细胞内Ca ^2+的浓度，但Ca包囊期间不一定发生²⁺流入。Ca ²⁺图像分析表明，Ca ²⁺在温度刺激后60 s内以囊泡结构存储并释放到细胞质中。Ca ²⁺从囊泡中释放后，多个信号通路被激活，而cAMP是候选的第二信使，在温度诱导的包囊过程中起着至关重要的作用。需要进一步的研究以阐明温度感测和Ca ²⁺从囊泡释放的机制。