May 2, 2013

If cells had their own soundtracks, I think any flagella-wielding cells would take home the prize.  Maybe the soundtrack begins on a high note with Devo’s “Whip It!”, continues on to the more crass Clarence Carter, plateaus with some headbanging death metal, and finally pays homage to Flock of Seagulls simply due to their flagellar waveform hair.  Today’s image is from a paper describing an outer-inner dynein link in flagella.

Flagella are whip-like organelles protruding from cells, and function to move fluid past the cell to generate motility.  In flagella, nine doublets of microtubules are bundled around a central microtubule pair (the 9+2 structure).  Outer dynein arms (ODAs) and inner dynein arms (IDAs) drive movement of the microtubule doublets past each other, generating the flagellar beating motion.  The ODA and IDA play distinct roles in flagellar function, but a recent paper finds a link between them.  Oda and colleagues found that intermediate chain 2 (IC2) of ODAs functions as part of the outer-inner dynein linker.  IC2 is a hub between ODAs and IDAs to regulate flagellar beating, based on the beating motion of IC2 mutants in the green algae Chlamydomonas.  The images above show the waveforms and image sequences of swimming Chlamydomonas cells.  The bending of flagella in wild-type cells (top row) is different from that of ic2 mutant cells (bottom row).  The principle bend at the flagellar tip in the forward stroke persists in the mutant (arrowhead); this altered bending results in slower swimming for the mutants.

Oda, T., Yagi, T., Yanagisawa, H., & Kikkawa, M. (2013). Identification of the Outer-Inner Dynein Linker as a Hub Controller for Axonemal Dynein Activities Current Biology, 23 (8), 656-664 DOI: 10.1016/j.cub.2013.03.028
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