CHARACTERIZATION OF A FAMILY OF REPETITIVE SEQUENCES THAT IS ELIMINATED LATE DURING MACRONUCLEAR DEVELOPMENT OF THE HYPOTRICHOUS CILIATE STYLONYCHIA-LEMNAE

A repetitive element from the hypotrichous ciliate Stylonychia lemnae was characterized by restriction and hybridization analysis. This repe titive element is present in about 5,000-7,000 copies per haploid geno me In the micronucleus and the macronuclear anlagen. Its DNA sequence is very conserved, but the length of the repetitive sequence blocs is variable. In some cases, it is associated with telomeric sequences and macronucleus-homologous sequences. Restriction analysis of genomic mi cronuclear and macronuclear anlagen DNA and in situ hybridization show ed that the repetitive sequences are amplified during the formation of polytene chromosomes. They are localized in many bands of the polyene chromosomes and are eliminated during the degradation of the polytene chromosomes. Possible functions of the repetitive sequences during ma cronuclear differentiation are discussed. (C) 1997 Wiley Liss, Inc.