Evidence for cortical control of macronuclear behavior in Stentor

✍ Scribed by Noël de Terra

• Publisher: John Wiley and Sons
• Year: 1971
• Tongue: English
• Weight: 749 KB
• Volume: 78
• Category: Article
• ISSN: 0021-9541
• DOI: 10.1002/jcp.1040780307

✦ Synopsis

In Stentor, the changes i n macronuclear morphology which occur during oral differentiation are known to be regulated by a corresponding series of cytoplasmic changes. The present experiments were designed to determine whether these changes are transmitted to the nucleus through the endoplasm or through the cortex. When two stentors in different stages of regeneration are grafted together, they normally become synchronized with respect to macronuclear behavior. The experimental results described i n this paper show that the stimulus responsible for synchronizing the nuclei of such graft complexes is transmitted with greatly decreased efficiency when the two graft components are separated by a continuous barrier of reversed cortex but share a common endoplasm. When the cortical barrier is incomplete, nuclear synchronization almost always occurs. These findings indicate that the cytoplasmic signals regulating macronuclear morphology are transmitted to the nucleus from the cortex; they further suggest that the synchronizing stimulus travels through the cell membrane rather than the cortical fibrillar system and that it is not released into the endoplasm but acts on the subcortically located macronucleus a t close range.