ISSN:
0886-1544
Keywords:
dynein
;
flagella
;
Chlamydomonas mutants
;
viscosity
;
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Medicine
Notes:
The propulsive force generated by Chlamydomonas mutants deficient in flagellar dynein was estimated from their swimming velocities in viscous media. The force produced by wild-type cell increased by 30-40% when viscosity was raised from 0.9 to 2 cP but decreased as viscosity was further raised above 6 cP. The biphasic dependence of force generation on viscosity was also observed in the mutant idal, which lacks the II component of the inner-arm dynein. The mutant ida4, which lacks the inner-arm 12 component, was extremely susceptible to viscosity and stopped swimming at 6 cP, at which other mutants could swim. In contrast, odal, which lacks the entire dynein outer arm, produced a fairly constant force of about one-third of the wild-type value, over a viscosity range of 0.9-11 cP. In demembranated and reactivated cell models of the wild type, the propulsive force decreased monotonically as viscosity increased. Thus the increase in force generation at about 2 cP observed in live cells may be caused by some unknown mechanism that is lost in cell models. The cell models of odal, in contrast, did not show a marked change in force generation with the change in viscosity. These results indicate that the force generation by the outer-arm dynein greatly depends on viscosity or the velocity of movement, whereas the complete set of inner-arm dynein present in the odal axoneme produces a fairly constant force at different viscosities. These different properties of inner and outer dynein arms should be important in the mechanism that produces flagellar beating.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cm.970310205
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