McFadden G I, Schulze D, Surek B, Salisbury J L, Melkonian M
J Cell Biol. 1987 Aug;105(2):903-12. doi: 10.1083/jcb.105.2.903.
A rapid, Ca2+-dependent change in the angle between basal bodies (up to 180 degrees) is associated with light-induced reversal of swimming direction (the "photophobic" response) in a number of flagellated green algae. In isolated, detergent-extracted, reactivated flagellar apparatus complexes of Spermatozopsis similis, axonemal beat form conversion to the symmetrical/undulating flagellar pattern and basal body reorientation (from the antiparallel to the parallel configuration) are simultaneously induced at greater than or equal to 10(-7) M Ca2+. Basal body reorientation, however, is independent of flagellar beating since it is induced at greater than or equal to 10(-7) M Ca2+ when flagellar beating is inhibited (i.e., in the presence of 1 microM orthovanadate in reactivation solutions; in the absence of ATP or dithiothreitol in isolation and reactivation solutions), or when axonemes are mechanically removed from flagellar apparatuses. Although frequent axonemal beat form reversals were induced by varying the Ca2+ concentration, antiparallel basal body configuration could not be restored in isolated flagellar apparatuses. Observations of the photophobic response in vivo indicate that even though the flagella resume the asymmetric, breaststroke beat form 1-2 s after photostimulation, antiparallel basal body configuration is not restored until a few minutes later. Using an antibody generated against the 20-kD Ca2+-modulated contractile protein of striated flagellar roots of Tetraselmis striata (Salisbury, J. L., A. Baron, B. Surek, and M. Melkonian, 1984, J. Cell Biol., 99:962-970), we have found the distal connecting fiber of Spermatozopsis similis to be immunoreactive by indirect immunofluorescence and immunogold electron microscopy. Electrophoretic and immunoblot analysis indicates that the antigen of S. similis flagellar apparatuses consists, like the Tetraselmis protein, of two acidic isoforms of 20 kD. We conclude that the distal basal body connecting fiber is a contractile organelle and reorients basal bodies during the photophobic response in certain flagellated green algae.
在许多具鞭毛的绿藻中，基体之间角度的快速、钙离子依赖性变化（可达180度）与光诱导的游动方向反转（“畏光”反应）相关。在分离的、经去污剂处理后再激活的相似精子藻鞭毛装置复合体中，当钙离子浓度大于或等于10⁻⁷ M时，轴丝搏动形式会转变为对称/波动的鞭毛模式，同时基体重新定向（从反平行构型变为平行构型）。然而，基体重新定向与鞭毛搏动无关，因为当鞭毛搏动被抑制时（即在再激活溶液中存在1 μM原钒酸盐；在分离和再激活溶液中不存在ATP或二硫苏糖醇），或者当轴丝从鞭毛装置中机械移除时，在大于或等于10⁻⁷ M的钙离子浓度下仍会诱导基体重新定向。尽管通过改变钙离子浓度可频繁诱导轴丝搏动形式反转，但在分离的鞭毛装置中无法恢复反平行的基体构型。对体内畏光反应的观察表明，即使鞭毛在光刺激后1 - 2秒恢复不对称的蛙泳搏动形式，但反平行的基体构型直到几分钟后才恢复。利用针对条纹鞭毛藻有条纹鞭毛根部20-kD钙离子调节收缩蛋白产生的抗体（索尔兹伯里，J. L.，A. 巴伦，B. 苏雷克，和M. 梅尔科尼安，1984，《细胞生物学杂志》，99:962 - 970），我们通过间接免疫荧光和免疫金电子显微镜发现相似精子藻的远端连接纤维具有免疫反应性。电泳和免疫印迹分析表明，相似精子藻鞭毛装置的抗原与条纹鞭毛藻蛋白一样，由两种20 kD的酸性同工型组成。我们得出结论，远端基体连接纤维是一种收缩细胞器，在某些具鞭毛的绿藻的畏光反应中使基体重新定向。
