Isolation and partial characterization of flagellar tubulin from Marsilea vestita

Very little biochemical work has been done on plant cell tubulin. In this study, tubulin was isolated from sperm cell flagella from the fern Marsilea vestita. Electrophoresis of reduced and carboxymethylated Marsilea tubulin on three different gel systems revealed that Marsilea tubulin consisted of α- and β-bands, as do the better-known animal and protist tubulins. Comparison of the electrophoretic mobilities of Marsilea, Aspergillus, Chlamydomonas and bovine tubulin showed that Marsilea tubulin's behavior is unique but is most like that of Chlamydomonas. The effects in vivo of tubulin-specific drugs were also examined. Mitosis of Marsilea microspores was sensitive to colchicine, podophyllotoxin and vinblastine, at concentrations higher than those necessary to obtain comparable effects in animal cells, but equivalent to those which block mitosis in Chlamydomonas. In addition, all three drugs, depending on the stage at which they were administered, either prevented flagellar growth or caused formation of abnormal flagella. It thus appears that Marsilea has microtubules similar in many ways to the better characterized animal microtubules but also demonstrating unique characteristics.