rDNA amplification in previtellogenic and vitellogenic oocytes of symphylans (Arthropoda, Myriapoda).
Tube-shaped ovaries of symphylans house numerous developing oocytes that are accompanied by somatic follicular cells. Oocyte nuclei (germinal vesicles) are relatively large and ovoid. During early previtellogenesis they contain compact spherical bodies and lampbrush chromosomes immersed in a translucent karyoplasm. Fluorescent labeling with DAPI and propidium iodide has revealed the presence of both DNA and RNA in the spherical bodies. As previtellogenesis advances, small RNA- and AgNOR-positive nucleoli bud off from these bodies. Full-grown nucleoli consist of coarse-granular material and comprise electron-transparent vacuoles. Our results suggest that in symphylan germinal vesicles amplification of rDNA genes takes place, and that the spherical bodies represent accumulations of extrachromosomal rDNA (rDNA bodies) after commencement of transcriptional activity.
Jabłońska
A
A
Department of Systematic Zoology, Institute of Zoology, Jagiellonian University, Cracow, Poland.
Szklarzewicz
T
T
Jankowska
W
W
Kukiełka
M
M
Biliński
S M
SM
D000818:Animals; D001181:Arthropods / Q000235:genetics* / Q000254:growth & development* / Q000648:ultrastructure; D002466:Cell Nucleolus / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D022003:Cell Nucleus Structures / Q000235:genetics* / Q000378:metabolism / Q000648:ultrastructure; D002875:Chromosomes / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D004275:DNA, Ribosomal / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D005260:Female; D005784:Gene Amplification / Q000235:genetics*; D002479:Inclusion Bodies / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D008854:Microscopy, Electron; D009865:Oocytes / Q000378:metabolism* / Q000648:ultrastructure; D010053:Ovary / Q000254:growth & development / Q000378:metabolism / Q000648:ultrastructure; D012335:RNA, Ribosomal / Q000378:metabolism; D014158:Transcription, Genetic / Q000502:physiology; D014818:Vitellogenesis / Q000235:genetics*
D004275:DNA, Ribosomal; D012335:RNA, Ribosomal