Notas sobre la Flora de la Península de Yucatán IV: Marsilea vestita Hook. et Grev. var. vestita (Marsileaceae), un nuevo registro y comentarios sobre el género en la región

Marsilea vestita Hook. et Grev. var. vestita is reported for the first time from the Yucatan Peninsula Biotic Province. An overview of the family Marsileaceae in the region is presented. A key to the three species known for the area is provided, as well as habitat notes and a full description of the newly reported population of M. vestita var. vestita.

Cell cycle arrest allows centrin translation but not basal body formation during spermiogenesis inMarsilea

Spermiogenesis in the water fern Marsilea vestita is a rapid process that requires the de novo formation of basal bodies in a cytoplasmic particle known as a blepharoplast. Spermiogenesis is activated by placing dry spores into water and is dependent upon the translation of new proteins from stored mRNAs with little, if any, new transcription. We looked at the necessity of cell division cycles in the gametophyte as a prerequisite for the activation of centrin translation and for the consequent formation of blepharoplasts. Cell cycle arrest was induced by treatments of gametophytes with hydroxyurea, with olomoucine, or after RNAi, employing dsRNA derived from Marsilea cyclin A or cyclin B. In all cases, centrin is translated from stored mRNA at the normal time, approximately 4 hours after imbibition, and it accumulates to maximal levels ∼6 hours after imbibition. In spite of the fact that centrin is translated at essentially normal times and accumulates to nearly normal levels, no blepharoplasts form in the gametophytes where division cycles have been disrupted. These results provide a clear demonstration that the new translation of centrin, by itself, is insufficient for blepharoplast formation, the de novo formation of basal bodies, and the assembly of a motile apparatus.