Evidence of germline precursors in asexually reproducing Aeolosoma hemprichi and Aeolosoma viride (Annelida, Aeolosomatidae)

ABSTRACT Germline precursors that can be present in asexual animals have never been characterized in aeolosomatids, minute meiofaunal Annelida usually reproducing by paratomic fission with pygidial budding. We investigated if Aeolosoma hemprichi and Aeolosoma viride still have the ability to naturally produce germ cells using an antibody raised against Vasa protein, which is a conserved germline marker. In A. hemprichi the anti-Vasa antibody recognized groups of cells floating in the coelom of the first zooid in subgroups that produce only a few eggs sporadically and also in those reproducing exclusively by paratomic fission. The presence of Vasa was also detected in the asexually formed second zooid. In A. viride, devoid of natural sexuality, the antibody evidenced randomly distributed cells in the coelomic cavity of the first zooid. Western blots of total protein extracts of adult animals of both species detected the presence of Vasa as a single band with a molecular weight corresponding to that observed in other polychaetes. The positive response of Vasa in western blots, along with the presence of labelled cells in the coelom of A. viride and in the growing zooid of A. hemprichi, suggest the ability to transmit the germline precursors asexually.