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Free and membrane-bound polyribosomes in normal and Rauscher-virus-infected mouse spleen cells
Abstract:
1. Free and membrane-bound polyribosomes and ribosomal monomers were isolated from normal and Rauscher-virus-infected mouse spleens by means of discontinuous sucrose density gradients. 2. The addition of ribonuclease inhibitor from rat liver was essential to protect these polyribosomes from degradation. To separate the smooth and rough membranes from ribosomal monomers an additional centrifugation step through a continuous sucrose density gradient was necessary. 3. After infection a marked increase in rRNA from both membrane-bound and free polyribosomes was observed. Treatment of the membrane-bound polyribosomes with sodium deoxycholate yielded only 80S particles even when ribonuclease inhibitor was added. 4. A striking feature of the infected spleen was the occurrence of large polyribosomes. Up to 40 monomers per polyribosome could be counted on electron micrographs.
Insights
Rauscher virus infection in mice significantly increases ribosomal RNA in spleen polyribosomes, leading to the formation of exceptionally large polyribosomes, up to 40 monomers each.
Area of Science:
- Molecular Biology
- Virology
- Cell Biology
Background:
- Polyribosomes, the active sites of protein synthesis, are crucial cellular components.
- Rauscher virus infection is known to affect cellular processes in mice.
Purpose of the Study:
- To investigate the impact of Rauscher virus infection on polyribosome structure and composition in mouse spleens.
- To characterize the changes in free and membrane-bound polyribosomes post-infection.
Main Methods:
- Isolation of free and membrane-bound polyribosomes and ribosomal monomers from normal and infected mouse spleens using discontinuous sucrose density gradients.
- Utilization of ribonuclease inhibitor to prevent polyribosome degradation.
- Separation of membranes and monomers via continuous sucrose density gradient centrifugation.
- Analysis of polyribosomes using electron microscopy.
Main Results:
- Rauscher virus infection led to a marked increase in ribosomal RNA (rRNA) within both membrane-bound and free polyribosomes.
- Large polyribosomes, containing up to 40 monomers, were a prominent feature in infected spleens.
- Treatment of membrane-bound polyribosomes with sodium deoxycholate resulted in 80S particles, indicating dissociation.
Conclusions:
- Rauscher virus infection profoundly alters polyribosome dynamics in mouse spleens.
- The observed increase in rRNA and formation of large polyribosomes suggest significant changes in protein synthesis regulation during infection.