JGI V. carteri f. nagariensis Home

photo of volvox carterii

Volvox carteri, the 'fierce roller', is a multicellular chlorophyte alga, closely related to the single-celled Chlamydomonas reinhardtii. Volvox normally reproduces as an asexual haploid, but can be induced to undergo sexual differentiation and reproduction. The 48-hour life cycle allows easy laboratory culture and includes an embryogenesis program that features many of the hallmarks of animal and plant development. These features include embryonic axis formation, asymmetric cell division, a gastrulation-like inversion, and differentiation of germ and somatic cells. The ~2000 somatic cells in a Volvox spheroid are biflagellate and adapted for motility, while the ~16 large germ cells contained within the spheroid are non-motile and specialized for growth and reproduction. Volvox embryogensis generates the coordinated arrangement of somatic flagella and photosensing eye spots needed for the organism's characteristic forward rolling motion.

The draft sequence of the Volvox genome will provide fascinating insights into the evolution of multicellularity in the green algal lineage and beyond. Moreover, the Volvocales, the family that includes single-celled Chlamydomonas (whose genome sequence is already available) and Volvox, also includes several multicellular or colonial species with intermediate cell numbers and less complex developmental programming. Comparative genomic studies within this group promises further insights into the origin and evolution of multicellularity in eukaryotes.