Localization of mitochondrial ribosomal RNA on the chromatoid bodies of marine planarian polyclad embryos

Citation
K. Sato et al., Localization of mitochondrial ribosomal RNA on the chromatoid bodies of marine planarian polyclad embryos, DEVELOP GR, 43(2), 2001, pp. 107-114
Citations number
30
Categorie Soggetti
Cell & Developmental Biology
Journal title
DEVELOPMENT GROWTH & DIFFERENTIATION
ISSN journal
00121592 → ACNP
Volume
43
Issue
2
Year of publication
2001
Pages
107 - 114
Database
ISI
SICI code
0012-1592(200104)43:2<107:LOMRRO>2.0.ZU;2-H
Abstract
Electron-dense cytoplasmic structures, referred to as chromatoid bodies, ar e observed in the somatic stem cells, called neoblasts, and germline cells in adult planarians. Although it has been revealed that the chromatoid bodi es morphologically resemble germline granules in Drosophila and Xenopus emb ryos, what essential role it plays in the planarian has remained unclear. i n the present study, to examine whether chromatoid bodies in planarian embr yos are responsible for germline formation, the presence and behavior of ch romatoid bodies during embryogenesis were examined. Mitochondrial large rib osomal RNA and mitochondrial small ribosomal RNA were used as candidate mar kers for components of the chromatoid body. Starting from the fertilized eg g, extramitochondrial signals of both RNA (mtrRNA) were observed. At the ul trastructural level, mtrRNA were localized on the surface of the chromatoid bodies. At subsequent stages, the signals of mtrRNA were observed in certa in restricted blastomeres that contribute to the formation of larval struct ures. The signals gradually decreased from the gastrula stage. These result s suggest that the chromatoid bodies associated with mtrRNA in embryogenesi s are not germline granules. The chromatoid bodies of blastomeres may be co ncerned with the toti- or pluripotency and cell differentiation as proposed in adult planarian neoblasts.