| Volvox carteri is a multicellular green alga comprised of two distinct cell types: ~16 large reproductive cells called gonidia and ~ 2000 small motile somatic cells. The cells of a V. carteri individual are arranged spherically, with the somatic cells distributed at the surface of the spheroid, and the gonidia positioned slightly below. Since V. carteri possesses a basic 3-dimensional morphology and exhibits the simplest type of complete division of labor, it is an ideal system to study fundamental developmental mechanisms. Commonly found developmental mutants are caused by defects in members of the gls, inv and reg gene families, which disrupt asymmetric division, spheroid morphology, and somatic cell fate, respectively. Previously Jordan and Idaten, two cold-inducible transposons, were used to tag and clone several genes from these developmental mutant classes. Unfortunately, however, extensive efforts to tag and clone certain types of developmental genes with these transposons have failed. Therefore it is imperative that we find additional active transposons to improve our transposon tagging system. To this end, we retrieved the sequences of 14 putative transposons of the cut-and-paste (class II) type from the JGI database and have used bioinformatic tools and Southern analysis to characterize these families and test them for their level of transposition. From this work, we classified six of the fourteen transposon families as being highly active and the remaining eight as relatively inactive. The identification of these active class II families should greatly improve our transposon tagging approaches to find, clone, and characterize novel genes.
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