Triton X-100-extracted mouse sperm treated with 0.1 mM ATP and 1.0 mM Ca2 exhibit an extremely coiled configuration that has been previously described as a curlicue. Sperm in the curlicue configuration exhibit a monotonically curved flagellum where the shear angle of the flagellum can reach a value as high as 14 radians at the flagellar tip. We utilized this strong reaction to Ca2 to elucidate the mechanism of the calcium response. The disintegration of the axoneme was facilitated by the use of an extraction procedure that removed the mitochondrial sheath without eliminating the calcium response. The order of emergence of the doublet microtubule outer dense fiber complexes was observed in the presence and absence of added Ca2 . The identity of the emergent elements was confirmed by transmission electron microscopy. Ca2 altered the order of emergence of internal axoneme elements to favor the appearance of the elements of the 9-1-2 side of the axoneme. These elements are propelled baseward by the action of dyneins on doublets 1 and 2. It was also possible to establish that the motive force for maintaining the curlicue configuration is dynein-based. The curlicues were relaxed by inhibition with 50 μM NaVO3 and were reestablished by disinhibiting the vanadate with 2.5 mM catechol.
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18 January 2012
The Calcium Response of Mouse Sperm Flagella: Role of Calcium Ions in the Regulation of Dynein Activity
Kathleen A. Lesich,
Courtney B. Kelsch,
Kristen L. Ponichter,
Benjamin J. Dionne,
Loan Dang,
Charles B. Lindemann
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Biology of Reproduction
Vol. 86 • No. 4
April 2012
Vol. 86 • No. 4
April 2012
axoneme
calcium
curlicue
dynein
flagellar motility
hyperactivation
outer dense fibers