Bloodgood R A, Levin E N
J Cell Biol. 1983 Aug;97(2):397-404. doi: 10.1083/jcb.97.2.397.
Mating in Chlamydomonas is a complex process initiated by contact of gametic flagellar surfaces, resulting in transmission of a signal from the flagella to the cell bodies. This signal triggers later events of cell wall loss, mating structure activation, and cell-cell fusion. Little is known about the nature of the signal or the role of Ca in these events. It was found that extracellular Ca is not necessary for successful mating in Chlamydomonas. However, cells will take up Ca from the medium in a linear manner for many hours and will accumulate micromolar concentrations, presumably by sequestering Ca within intracellular storage sites. If gametic cells of one mating type (preloaded with 45Ca) are mated with gametes of the opposite mating type (preloaded with unlabeled calcium), there is a rapid, transient increase in calcium efflux rate (20 times that of the control) that lasts approximately 6 min. This effect is not associated with cell-cell fusion, since the same observation is made if (+) gametes preloaded with 45-Ca are agglutinated by isolated flagella from (-) gametes preloaded with unlabeled Ca. Other experiments have shown that the increased efflux rate is not a simple consequence of cell wall release. Ca efflux in unmated gametes is greatly reduced in deflagellated cells, suggesting that much of the Ca movement is associated with the flagellar membrane. Although signaling itself may involve Ca fluxes across the flagellar membrane, it is also possible that a consequence of signaling is release of Ca from intracellular storage sites (perhaps functional equivalents of the sarcoplasmic reticulum). The observed transient increase in Ca efflux rate may reflect a transient increase in the cytoplasmic free-Ca concentration. This increase in cytoplasmic Ca may regulate the later events in mating (such as cell wall release and mating structure activation).
衣藻的交配是一个复杂的过程，由配子鞭毛表面的接触引发，导致信号从鞭毛传递到细胞体。这个信号触发了随后的细胞壁丢失、交配结构激活和细胞间融合等事件。关于该信号的性质或钙在这些事件中的作用，人们所知甚少。研究发现，细胞外钙对于衣藻成功交配并非必需。然而，细胞会以线性方式从培养基中摄取钙长达数小时，并积累微摩尔浓度的钙，推测是通过将钙螯合在细胞内储存位点来实现的。如果一种交配类型的配子细胞（预先加载了45Ca）与相反交配类型的配子（预先加载了未标记的钙）交配，钙外流速率会迅速短暂增加（是对照的20倍），持续约6分钟。这种效应与细胞间融合无关，因为如果预先加载了45Ca的（+）配子被预先加载了未标记钙的（-）配子的分离鞭毛凝集，也会观察到相同的现象。其他实验表明，增加的外流速率并非细胞壁释放的简单结果。去鞭毛细胞中未交配配子的钙外流大大减少，这表明大部分钙的移动与鞭毛膜有关。虽然信号传导本身可能涉及钙通过鞭毛膜的通量，但信号传导的一个结果也可能是钙从细胞内储存位点释放（可能是肌浆网的功能等效物）。观察到的钙外流速率的短暂增加可能反映了细胞质游离钙浓度的短暂增加。细胞质钙的这种增加可能调节交配后期的事件（如细胞壁释放和交配结构激活）。
