Eshel D, Brokaw C J
Cell Motil Cytoskeleton. 1987;7(2):160-8. doi: 10.1002/cm.970070208.
Time-averaged data covering six to ten beat cycles for ATP-reactivated spermatozoa of a sea urchin and Ciona, and from a uniflagellate mutant of Chlamydomonas, were analyzed to obtain parameters of oscillation and mean shear angle at each point along the flagellum. The mean shear angles usually show a sharp change near the base of the flagellum. This sharp basal change in angle is correlated with perceived asymmetry in the development times of principal and reverse bends when these bends are measured directly from the asymmetric bending patterns, without subtracting out the mean shear angle. The asymmetry in development times was previously considered to be evidence against a "biased baseline" mechanism for asymmetric bending waves, in which completely symmetric bending waves develop and propagate on a curved flagellum. Our analysis now shows that the asymmetry in development times can be fully explained by the presence of a sharp static bend near the base of the flagellum, which can confuse the determination of the times of initiation of new bends at the base of the flagellum. Our reinterpretation of these data removes previous objections to the "biased baseline" mechanism for the regulation of bending wave asymmetry by calcium, and supports other evidence favoring a biased baseline mechanism, rather than a "biased switching" mechanism.
对海胆、玻璃海鞘经ATP激活的精子以及衣藻单鞭毛突变体的六到十个搏动周期的时间平均数据进行了分析，以获取沿鞭毛各点的振荡参数和平均剪切角。平均剪切角通常在鞭毛基部附近呈现急剧变化。当直接从不对称弯曲模式测量主弯曲和反向弯曲的发育时间，而不减去平均剪切角时，这种基部角度的急剧变化与主弯曲和反向弯曲发育时间的感知不对称相关。发育时间的不对称性以前被认为是反对不对称弯曲波“偏向基线”机制的证据，在该机制中，完全对称的弯曲波在弯曲的鞭毛上形成并传播。我们现在的分析表明，发育时间的不对称性可以完全由鞭毛基部附近存在的急剧静态弯曲来解释，这会混淆对鞭毛基部新弯曲起始时间的确定。我们对这些数据的重新解释消除了以前对钙调节弯曲波不对称性的“偏向基线”机制的反对意见，并支持了其他有利于偏向基线机制而非“偏向切换”机制的证据。
