Isolated flagellar apparatus of Chlamydomonas: characterization of forward swimming and alteration of waveform and reversal of motion by calcium ions in vitro.
Isolated flagellar apparatus of Chlamydomonas: characterization of forward swimming and alteration of waveform and reversal of motion by calcium ions in vitro.
复制标题
衣藻的分离鞭毛装置：体外钙离子向前游动、波形改变和反向运动的特征。
作者：
J. Hyams;G. Borisy
本文报道了双鞭毛绿色衣藻（Chlamydiumreinhardtii）鞭毛器（2个鞭毛附着在各自的基体和附属结构上）的体外再活化，以研究其鞭毛活性的控制。在ImM三磷酸腺苷（ATP）存在下的分离装置的波形和拍频与活细胞记录的波形和拍频相当。等摩尔浓度的二磷酸腺苷（ADP）可替代ATP，而搏动频率变化不大，波形无明显变化，表明后者由轴丝腺苷酸激酶转化为ATP。腺苷酸（AMP）没有再激活。但胞苷、鸟苷和尿苷三磷酸（CTP、GTP和UTP）的频率约为ATP的10%。在APT和ADP中，在pH 6.4和pH 8.9之间的宽pH范围内，再活化是最佳的。外源钙离子可诱导离体鞭毛器由正向运动转变为反向运动。这两种类型的运动与活细胞的记录反应直接相当。当钙水平低于10（-6）M时，发生向前游泳，当钙水平高于10（-6）M时，分离的装置变为向后运动。浓度高于10（-3）M时，运动受到抑制。当鞭毛膜用去污剂溶解时，钙逆转运动的阈值降低到10（-7）M，表明鞭毛膜参与轴丝内钙水平的调节。钙引起的运动逆转本身是自由可逆的。这些意见的关系，已知的战术反应衣原体进行了讨论。
The control of flagellar activity in the biflagellate green alga, Chlamydomonas reinhardtii was investigated by the in vitro reactivation of the isolated flagellar apparatus (the 2 flagella attached to their respective basal bodies plus accessory structures). The waveform and beat frequency of the isolated apparatus in the presence of 1 mM adenosine triphophate (ATP) were comparable to those recorded for living cells. Equimolar concentrations of adenosine diphosphate (ADP) could be substituted for ATP with little change in beat frequency and no apparent change in waveform, suggesting that the latter is converted to ATP by axonemal adenylate kinase. No reactivation occurred in adenosine monophosphate (AMP). But frequencies in cytidine, guanosine and uridine triphosphates (CTP, GTP and UTP) were approximately 10% that obtained in ATP. Reactivation was optimal over a broad pH range between pH 6.4 and pH 8.9 in both APT and ADP. Isolated flagellar apparatus could be induced to change from forward to reverse motion in vitro by manipulation of exogenous calcium ions. The 2 types of motion were directly comparable to recorded responses of living cells. Forward swimming occurred at levels of calcium below 10(-6)M, the isolated apparatus changing to backward motion above this level. Motility was inhibited at concentrations above 10(-3)M. The threshold for reversal of motion by calcium was lowered to 10(-7)M when the flagellar membranes were solubilized with detergent, indicating that the flagellar membranes are involved in the regulaion of the level of calcium within the axoneme. The reversal of motion by calcium was itself freely reversible. The relationship of these observations to the known tactic responses of Chlamydomonas is discussed.