Effect of cycloheximide on RNA synthesis inChironomuspolytene chromosomes

✍ Scribed by J. L. Díez; M. C. Santa-Cruz; P. Aller

• Publisher: Springer
• Year: 1977
• Tongue: English
• Weight: 651 KB
• Volume: 61
• Category: Article
• ISSN: 0009-5915
• DOI: 10.1007/bf00288620

✦ Synopsis

Modifications in the synthesis of salivary gland RNA were induced by treatments with 10 microgram/ml cycloheximide (CHM) on 4th instar larvae of Chironomus pallidivitattus. After 3, 6 and 24 h CHM treatment, RNA was labeled "in vitro", by incubating the salivary glands in a medium containing H3-uridine. The electrophoretical analyses corresponding to the 3 and 6 h treatment showed a stimulation of the non-ribosomal components of the newly synthesized RNA, while preribosomal RNA synthesis appeared depressed. This fact was also confirmed at cytological level, since autoradiograms made after 3 h of CHM treatment showed a reduced H3-uridine label over the nucleolus and an increase of diffuse labeling over the chromosomes. Longer treatments (24 h) causes a considerable inhibition of the synthesis of all RNA species. The role played by protein synthesis inhibition in the aforementioned effects is discussed.--Some of the morphological implications of CHM treatment, such as modifications of the nucleolar structure (nucleolar segregation) are also reported. The use of a squash technique based on glutaraldehyde fixation of the salivary glands, considerably facilitates such studies.