title: [Karyosphere capsule in Tribolium castaneum oocytes].
abstract: 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) 5'-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.
authors.forename: F M
authors.initials: FM
authors.lastname: Batalova
authors.forename: D S
authors.initials: DS
authors.lastname: Bogoliubov
mesh_terms: D000199:Actins / Q000235:genetics / Q000378:metabolism; D000818:Animals; D002843:Chromatin / Q000378:metabolism / Q000648:ultrastructure*; D059006:Chromosomes, Insect; D015870:Gene Expression; D006151:Guanosine / Q000031:analogs & derivatives / Q000378:metabolism; D034921:Lamin Type B / Q000235:genetics / Q000378:metabolism; D049469:Meiotic Prophase I; D015530:Nuclear Matrix / Q000378:metabolism / Q000648:ultrastructure*; D009865:Oocytes / Q000254:growth & development / Q000378:metabolism / Q000648:ultrastructure*; D009866:Oogenesis / Q000235:genetics; D012342:RNA, Small Nuclear / Q000235:genetics / Q000378:metabolism; D017411:Ribonucleoproteins, Small Nuclear / Q000235:genetics / Q000378:metabolism; D014231:Tribolium / Q000235:genetics / Q000254:growth & development / Q000648:ultrastructure*
chemical_list: D000199:Actins; D002843:Chromatin; D034921:Lamin Type B; D012342:RNA, Small Nuclear; D017411:Ribonucleoproteins, Small Nuclear; D006151:Guanosine; C017778:N(2),N(2),7-trimethylguanosine