Messenger RNA in the cytoskeletal framework: analysis by in situ hybridization.

Abstract

The possibility of an association of mRNA with the cytoskeletal framework (CF) of ascidian (Styela plicata) follicle cells was examined in this study. The approach was to extract the follicle cells with Triton X-100 and determine whether mRNA persisted in the insoluble residue by 2 methods, in situ hybridization with poly(U) and actin DNA probes and the incorporation of radioactive isotopes into RNA. Triton X-100 extraction of follicle cells yielded a filamentous CF containing .apprx. 70% of the total poly (A) but only 9% of the total lipid, 23% of the total protein and 28% of the total RNA. In situ hybridization with a poly (U) probe indicated that .apprx. 70% of the poly (A) was associated with the CF. In situ hybridization with a cloned actin DNA probe indicated that .apprx. 60% of the actin mRNA was associated with the CF. Autoradiography of detergent-extracted follicle cells, which were labeled with [3H]uridine or [3H]adenosine, indicated that > 90% of the newly synthesized poly (A)+RNA was preserved in the CF. More newly synthesized mRNA than steady-state mRNA may be present in the Triton X-100 insoluble fraction. A significant proportion of the mRNA complement of ascidian follicle cells is associated with the CF.