Research Area

Our experimental search for rules that govern the initiation and propagation of bends by flagella proceeds in parallel with computer simulation studies using programs that solve the partial differential equation for the balance of active and resistive bending moments on a flagellum. This "black box biophysics" type of approach is made possible by the many variant bending patterns that can be obtained by manipulating the in vitro conditions for motility of the flagella. Since bending is generated by sliding between microtubules, measuring this sliding is important. Recent work has used gold beads as markers on exposed outer doublet microtubules in order to make direct measurements of microtubule sliding. A second theme is analysis of the signal transduction steps involved in activation of the motility of Ciona spermatozoa. The first step is triggered by transfer from a high potassium ion environment to a low potassium environment, and results in an increase in cAMP concentration within the intact spermatozoa. Subsequent steps are blocked by inhibitors of protein phosphorylation, and can be carried out in vitro after sperm demembranation, by incubating the demembranated spermatozoa in the presence of cAMP and ATP. The initial steps of in vitro activation are blocked by specific inhibitors of cAMP-dependent kinase, but the final steps are carried out by a kinase (or more than one) that is not sensitive to these inhibitors. The flagellar axoneme carries several different tightly-bound kinases, with as yet unknown function.

Current Members

Brokaw, Charles J (Principal Investigator/Director)

Contact

Institution: Caltech

Address:
Caltech - The Division of Biology and Biological Engineering
188 Alles Laboratory
1200 E California Blvd
Pasadena, CA
91125, USA

Web Page: http://www.its.caltech.edu/~brokawc/home.html

General/Lab Fax: 626-395-4927