Interaction between chromatoid bodies and mitochondria in neoblasts and gonial cells of the asexual and spontaneously sexualized planarian,Girardia (Dugesia) tigrina

Pluripotent Gametogenic Stem Cells of Asexually Reproducing Invertebrates

“…The export of the ribosomal RNAs from mitochondria to the germinal granules is no longer questioned, but the mechanism underlying a transport is considered unprecedented and enigmatic (Kashikawa et al, 1999;Ding & Lipshitz, 1993;Amikura et al, 2001). Our ultrastructural data indicating the disruption of the outer mitochondrial membrane and the transformation of the mitochondrial matrix with inner membrane cristae into material of germinal granules in representatives of various animal taxa may clarify the mechanism of the export of mitochondrial components into germinal granules (Reunov et al, 2000;Reunov et al, 2004;Isaeva et al, 2005. This phenomenon enables us to suppose the participation of mitochondria in the biogenesis of the germinal granules (Isaeva & Reunov, 2001;Isaeva et al, 2005.…”

“…We suggest that the structural frame of germinal granules derives from mitochondria and is filled with transcription products of the nuclear genome. The release of the mitochondrial matrix material in the germ plasm is the way to incorporate the mitochondrial derivatives into germinal granules, mediating the involvement of mitochondrial genome products in the biogenesis of the macromolecular complex of germinal determinants (Isaeva & Reunov, 2001;Isaeva et al, 2005. We propose also flows of molecular information connecting the nucleus, mitochondria, and germinal granules and involving in pluri/totipotency maintenance .…”

“…The presence of mitochondrial rRNAs outside of the mitochondria in association with germinal granules has been generally accepted; it becomes apparent that mitochondrial rRNAs and other products of the mitochondrial genome are involved in the formation of germline cells in diverse multicellular animals (Ikenishi, 1998;Kloc et al, 2000;Mahowald, 2001;Amikura et al, 2001;Matova & Cooley, 2001;Leatherman & Jongens, 2003;Seydoux & Braun, 2006). It has been suggested that products of both the nuclear and mitochondrial genomes are essential for the structural organization and functioning of the germinal granules of germ plasm (Kobayashi et al, 1998(Kobayashi et al, , 2005Ding & Lipshitz, 1993;Isaeva & Reunov, 2001;Isaeva et al, 2005. The export of mitochondrial rRNA from mitochondria to the polar granules in Drosophila depends on the activity of nuclear genes oskar, vasa, and tudor (Amikura et al, 2001;Matova & Cooley, 2001).…”

“…Our ultrastructural data indicating the disruption of the outer mitochondrial membrane and the transformation of the mitochondrial matrix with inner membrane cristae into material of germinal granules in representatives of various animal taxa may clarify the mechanism of the export of mitochondrial components into germinal granules (Reunov et al, 2000;Reunov et al, 2004;Isaeva et al, 2005. This phenomenon enables us to suppose the participation of mitochondria in the biogenesis of the germinal granules (Isaeva & Reunov, 2001;Isaeva et al, 2005. Destruction of the outer mitochondrial membrane and transformation of the mitochondrial matrix to the material of germinal granules or nuage have been revealed in the gonial cells of echinoderms and vertebrates (Reunov et al, 2000(Reunov et al, , 2004, planarian , sponge and hydroids .…”

“…The ability to differentiate into gametogenic and somatic cells was shown for archaeocytes and choanocytes in sponges (Simpson, 1984;Müller, 2006;Funayama, 2008;Funayama et al, 2010), interstitial cells in hydra and other cnidarians (Thomas & Edwards, 1991;Bode, 1996;, turbellarian neoblasts (Shibata et al, 1999;Peter et al, 2001;Isaeva et al, 2005), stem cells of colonial rhizocephalans , ascidian stem cells (Pancer et al, 1995;Stoner & Weissman, 1996;Stoner et al, 1999;Weissman, 2000). So, pluripotent stem cells in invertebrates with asexual reproduction are potentially gametogenic cells.…”