New Motilities and Motors in the Flagella of Chlamydomonas

Abstract

Chlamydomonas is a haploid, unicellular green alga, about 10 µm in diameter. Synchronous cultures can be grown phototrophically in a simple defined medium. In addition to the two 10–12 µm-long flagella that emanate from one end of the cell, Chlamydomonas shares the cytology of typical higher plant and animal cells (e.g., basal bodies/centrioles, microtubules, actin filaments, chloroplasts, mitochondria, en-doplasmic reticulum, and Golgi). The genetics of Chlamydomonas is similar to that of yeast, with plus and minus cells mating to form zygotes, followed by meiosis and tetrad formation. Many mutants are available (Harris 1989) or can be generated by classical mutagenesis procedures. Because Chlamydomonas is easily transformed, with the introduced DNA inserting randomly into the genome (Diener et al. 1990; Kindle et al. 1989), mutants can also be generated by insertional mutagenesis, allowing for the isolation of mutant genes by plasmid rescue (Tam and Lefebvre 1993). In addition, progress is being made on gene cloning by complementation (Purton and Rochaix 1994) and on the selection of homologous recombinants (Sodeinde and Kindle 1993). We are using flagellar regeneration in this green alga as a model system for studying the biogenesis of cell organelles (Johnson and Rosenbaum 1993).