An immunoelectron study of karyosphere and nuclear bodies in oocytes of mealworm beetle, Tenebrio molitor (Coleoptera : Polyphaga)

Citation
D. Bogolyubov et al., An immunoelectron study of karyosphere and nuclear bodies in oocytes of mealworm beetle, Tenebrio molitor (Coleoptera : Polyphaga), CHROMOSOMA, 109(6), 2000, pp. 415-425
Citations number
43
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Molecular Biology & Genetics
Journal title
CHROMOSOMA
ISSN journal
0009-5915 → ACNP
Volume
109
Issue
6
Year of publication
2000
Pages
415 - 425
Database
ISI
SICI code
0009-5915(200009)109:6<415:AISOKA>2.0.ZU;2-C
Abstract
The karyosphere and nuclear bodies (NBs) were studied in Tenebrio molitor o ocytes using immunoelectron cytochemistry. During early diplotene (previtel logenic stage), oocyte chromosomes begin to unite in a small nuclear volume forming the karyosphere. In vitellogenic oocyte nuclei, the chromatin unde rgoes condensation, and the karyosphere acquires a ring-shaped structure. T he karyosphere is the only structure containing DNA in the oocyte nucleus. Pre-mRNA splicing factors [small nuclear ribonucleoproteins (snRNPs) and SC 35] are not found in the karyosphere itself. In previtellogenic oocyte nucl ei, these factors are present in NBs and in a fibrogranular substance surro unding the chromosomes in the early stages of karyosphere formation. At thi s stage, larger fibrillar NBs contain the non-snRNP splicing factor SC35. S maller roundish NBs were shown to contain snRNPs. Some NBs with the same mo rphology contain neither snRNPs nor SC35. In the vitellogenic oocyte, there are fibrogranular NBs containing both snRNPs and SC35 splicing factors, fi brillar NBs containing snRNPs only, and complex NBs containing both. Comple x NBs are often connected with the ring-shaped karyosphere. Based on the ob tained immunoelectron data, we suggest that T. molitor oocyte NBs containin g both snRNPs and the non-snRNP splicing factor SC35 are homologs of the we ll-characterized B-snurposomes in amphibian germinal vesicles and clusters of interchromatin granules in mammalian oocyte nuclei. Other NBs containing only snRNPs are suggested to represent a special class of insect oocyte sn urposomes. The nuclear organelles mentioned seem to play a role as storage domains for pre-mRNA splicing factors during T. molitor oogenesis.