Protistology 1 (4) 185–194 (2000)
Serotypes in the ciliate Dileptus anser : a case of non-Mendelian inheritance
Alexander L. Yudin and Zoya I. Uspenskaya
Institute of Cytology, Russian Academy of Sciences, St. Petersburg, Russia
Two Dileptus anser clones, B and D, isolated from natural reservoirs, had different serotypes when cultured under identical conditions in the laboratory (the classical immobilization test of infusoria with rabbit polyclonal antisera). Conjugation between the B cells (the mating type I) and D (the mating type III) resulted in exconjugant F1 clones. It turned out that all the F1 clones react with the both anti-"parental" immune sera, i.e., they have an intermediate, "hybrid" phenotype. Each of five different F1 clones was back-crossed with the both "parent" clones, B and D. Standard testing of F2 (i.e., B1) clones about in 5-10 weeks after the conjugation gave unexpected results: no segregation for "parental" serotypes was observed in this generation, and each of the 51 tested clones had the "hybrid" serotype that seemed to be the same as that of the F1 clones. Such a non-Mendelian inheritance of the studied character is discussed in terms of the epigene hypothesis (Tchuraev, 1975) and considering data on epigenetic control of the serotype expression in the classic objects of ciliate genetics, species of the Paramecium aurelia complex and Tetrahymena thermophila.
Key words: serotypes, i-antigens, regulation of gene expression, ciliates, Dileptus anser, non-Mendelian heredity, epigenetic variation and inheritance
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