Artificial induction of autogamy in Paramecium caudatum

Induction of autogamy by treatment with trypsin in Paramecium caudatum.

Firmly united conjugant pairs of P. caudatum were easily separated by treatment with trypsin, 0.025--1.0 mg/ml in 2 mM phosphate buffer at pH 7.2. Cytological observations showed that pairs separated by this means undergo normal meiosis and subsequent prezygotic divisions. Microspectrophotometric comparisons of G1 micronuclei in the parent with those in clones derived from prematurely separated...

Behavioral Mutants in PARAMECIUM CAUDATUM.

Mutants of Paramecium caudatum with abnormal swimming behavior or responses to cations were obtained by mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine. Some of the mutants, like pawn in P. tetraurelia, cannot swim backward and are called CNR. Seven independently obtained CNR mutants belonged to three complementation groups, designated as cnrA, cnrB and cnrC. Some characteristics of doubl...

The structure of trichocysts in Paramecium caudatum.

The structure of undischarged and discharged trichocysts has been examined in Paramecium caudatum, and their light-microscopic appearance compared with their fine-structural organization. In living specimens undischarged trichocysts appear to be of a single type with a unimodal variation in length about a mean of 37 fim. When fixed for electron microscopy or compressed beneath a coverslip many ...

Micronuclear Rna Synthesis in Paramecium Caudatum

In a generation time of 8 hr in Paramecium caudatum, the bulk of DNA synthesis detected by thymidine-(3)H incorporation takes place in the latter part of the cell cycle. The micronuclear cycle includes a G(1) of 3 hr followed by an S period of 3-3(1/2) hr. G(2) and division occupies the remaining period of the cycle. Macronuclear RNA synthesis detected by 5'-uridine-(3)H incorporation is contin...

Studies in the Respiration of Paramecium Caudatum