KARYOSPHERE CAPSULE IN TRIBOLIUM CASTANEUM OOCYTES
F.M. Batalova, D.S. Bogolyubov 1
Institute of Cytology RAS, St. Petersburg;
1 e-mail: dmitr@mail.cytspb.rssi.ru
Structure and composition of the karyosphere (karyosome) capsule were studied in the oocytes of a laboratory insect, Tribolium castaneum, with the use of electron
microscopy and immunoelectron cytochemistry. Basing on the study of nuclear structure dynamics, we distinguished 8 stages that characterize the period of oocyte growth.
At the diplotene stage, T. castaneum oocyte chromosomes conjoin early into a compact karyosphere, but a significant chromatin condensation does not occur. The process
of karyosphere formation is accompanied by the development of an extensive extrachromosome capsule surrounding chromatin. The capsule consists of a material of different
morphological types. Significant molecular components of the T. castaneum karyosphere capsule are represented by the proteins of nuclear matrix including F-actin and
lamin B. Besides the structural proteins, the Sm proteins of small nuclear (sn) RNPs and mature 2,2,7-trimethyl guanosine (TMG) 5R-capped snRNAs are revealed
immunocytochemically in the karyosphere capsule. The obtained data can form a basis for further expansion of ideas on the functions of the karyosphere capsule as a specialized
extrachromosomal nuclear domain of the oocytes. We believe that the T. castaneum karyosphere capsule plays not only a structural role, but may be involved directly in the
processes related to gene expression.
Key words: Tribolium castaneum, oocyte nucleus, extrachromosomal nuclear domain, karyosphere, karyosphere capsule, electron microscopy
| Back
| Contents
| Main |
