Thermal down-regulation of exportable rRNA in nuclei

✍ Scribed by Frank Wunderlich; Günter Giese; Gerhard Herlan

• Publisher: John Wiley and Sons
• Year: 1984
• Tongue: English
• Weight: 1016 KB
• Volume: 120
• Category: Article
• ISSN: 0021-9541
• DOI: 10.1002/jcp.1041200215

✦ Synopsis

Abstract

The export of rRNP particles from nuclei isolated from Tetrahymena was investigated after preincubating the nuclei at different temperatures under nonpermissive export‐conditions. We observed a new phenomenon: Temperature elevation from the sublethal cells' growth temperature, 8°C, to the optimal temperature, 28°C, lead to a gradual down‐regulation in the maximal proportion of rRNP particles subsequently exported from nuclei at 28°C. This thermal down‐regulation is apparently not due to qualitative changes in the exported rRNP particles, a derangement in the gross nuclear organization, a degradation and/or nicking of the nuclear rRNA, a gross decomposition of the major nuclear proteins, a random cross‐linking of nuclear components by disulfide bonds, or an elution of nuclear factors possibly required for rRNP export. Moreover, there is a corresponding thermal down‐regulation in nuclear envelope‐free nuclei. Our data indicate that nuclei possess a mechanism that regulates the number of potentially exportable rRNP particles at a level preceding the rRNP passage through the nuclear envelope.