CAJAL BODIES IN INSECT OOCYTES. I. IDENTIFICATION AND IMMUNOCYTOCHEMICAL CHARACTERIZATION OF CAJAL BODIES IN VITELLOGENIC OOCYTES OF THE YELLOW MEALWORM BEETLE, TENEBRIO MOLITOR

D. S. Bogolyubov

Institute of Cytology RAS, St. Petersburg, Russia;
e-mail: dmitr@link.cytspb.rssi.ru

In vitellogenic oocytes of Tenebrio molitor (inactive stage), numerous fibrogranular nuclear bodies (NBs) are present. Using immunofluorescent microscopy, these NBs were shown to contain pre-mRNA splicing factors (small nuclear [sn] RNPs and SR-protein, SC35) as well as RNA polymerase II. A limited set of NBs also contained coilin, a marker protein for Cajal bodies (CBs). We suggest that in T. molitor oocytes, coilin-containing NBs, which also contain splicing factors and RNA polymerase II, seem to represent CBs. In the species studied, no morphological features of CBs were established as compared with other NBs, which do not contain coilin. Microinjectons in oocytes of myc-tagged coilin mRNA, followed by revealing newly translated protein with antibody specific for this tag, have shown targeting of myc-coilin with CBs. The own and literary data on the morphology and molecular composition of CBs are discussed in terms of searching for critera for CB identification in cells of different origin, and at active and inactive stages.

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