Cloning of tetrahymena genomic sequences whose message abundance is increased during conjugation

Abstract

A molecular and biochemical inquiry into protein regulation during Tetrahymena thermophila conjugation was carried out in two ways: a two-dimensional gel analysis of newly translated proteins and the molecular cloning of genes whose message abundance is increased. The two-dimensional gel analysis indicated that the synthesis of 32 predominantly basic proteins was stimulated in conjugating cells. The induction of these proteins could not be correlated with length of starvation or with mating type. The transcription pattern and molecular organization of three clones of T. thermophila genomic DNA, selected on the basis of differential hybridization to conjugating or control cell RNA, were investigated. Two of the clones, which were homologous to transcripts detected in conjugating cells, showed no rearrangements between micro- and macronuclear DNA. A third clone was divided into three segments. One segment was homologous to sequences limited to the micronucleus. A second segment hybridized to a large number of restriction fragments of micronuclear DNA digested with HindIII but to only two fragments of macronuclear DNA. A third segment, which was complementary to one transcript in conjugating cells and to two different transcripts in control cells, hybridized to two fragments in micronuclear DNA and one fragment in macronuclear DNA.