title: Ribosomal RNA of Hyacinthus orientalis L. female gametophyte cells before and after fertilization.
abstract: The nucleolar activity of Hyacinthus orientalis L. embryo sac cells was investigated. The distributions of nascent pre-rRNA (ITS1), 26S rRNA and of the 5S rRNA and U3 snoRNA were determined using fluorescence in situ hybridization (FISH). Our results indicated the different rRNA metabolism of the H. orientalis female gametophyte cells before and after fertilization. In the target cells for the male gamete, i.e., the egg cell and the central cell whose activity is silenced in the mature embryo sac (Pięciński et al. in Sex Plant Reprod 21:247-257, 2008; Niedojadło et al. in Planta doi:                            10.1007/s00425-012-1599-9                                                     , 2011), rRNA metabolism is directed at the accumulation of rRNPs in the cytoplasm and immature transcripts in the nucleolus. In both cells, fertilization initiates the maturation of the maternal pre-rRNA and the expression of zygotic rDNA. The resumption of rRNA transcription observed in the hyacinth zygote indicates that in plants, there is a different mechanism for the regulation of RNA Pol I activity than in animals. In synergids and antipodal cells, which have somatic functions, the nucleolar activity is correlated with the metabolic activity of these cells and changes in successive stages of embryo sac development.
authors.affiliation: Department of Cell Biology, Institute of General and Molecular Biology, Nicolaus Copernicus University, Gagarina 9, 87-100, Toruń, Poland. karask@umk.pl
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Niedojadło
authors.forename: Szymon
authors.initials: S
authors.lastname: Pięciński
authors.forename: Dariusz Jan
authors.initials: DJ
authors.lastname: Smoliński
authors.forename: Elżbieta
authors.initials: E
authors.lastname: Bednarska-Kozakiewicz
mesh_terms: D002466:Cell Nucleolus / Q000235:genetics*; D005306:Fertilization / Q000235:genetics*; D018506:Gene Expression Regulation, Plant; D031423:Hyacinthus / Q000235:genetics* / Q000254:growth & development*; D056771:Ovule / Q000166:cytology / Q000254:growth & development*; D012318:RNA Polymerase I / Q000378:metabolism; D012335:RNA, Ribosomal / Q000378:metabolism*; D012639:Seeds / Q000166:cytology / Q000235:genetics*; D014158:Transcription, Genetic; D015533:Transcriptional Activation
chemical_list: D012335:RNA, Ribosomal; D012318:RNA Polymerase I