Overamplification of genes in macronuclei of hypotrichous ciliates

• Published in: Chromosoma Vol. 88; no. 2; pp. 156 - 163
• Main Author: Steinbr ck, G nther
• Format: Journal Article
• Language: English
• Published: 01-07-1983
• Subjects: Euplotes crassus; Euplotes vannus; Freshwater; Stylonychia lemnae
• ISSN: 0009-5915; 1432-0886
• DOI: 10.1007/BF00327337

The macronuclei of hypotrichous ciliates contain gene-sized DNA molecules. The copy number of individual gene-sized pieces is species-specific and different for different genes. Some strains of different hypotrichous ciliate species show an overamplification of one or a few individual gene-sized pieces in the macronucleus. The results of crossing experiments show that this relative overrepresentation of certain sequences in an inherent genetic property of the strain.The copy number increases with the age of the strain. Overamplified sequences may display sequence heterogeneity as revealed by restriction endonuclease digestion. They are transcribed into mRNA and seem, therefore, to code for proteins. However, no function related to these genes could be detected. The sequences that are overamplified in one strain do not crosshybridize with overamplified sequences in another strain. Strains of Stylonychia lemnae Euplotes vannus and Euplotes crassus were studied.