New stands of Paramecium dodecaurelia were found in Russia, Ukraine, Kazahstan, Poland, and Tenerife. Molecular studies (RAPD and sequencing of LSU rRNA and CO1 mtDNA gene fragments) of P. dodecaurelia strains depicted intraspecific polymorphism within the species, revealed as distinct differences between strains from the USA in comparison with strains from different regions of the Palearctic.

Cells of Paramecium caudatum in the immaturity period of the life cycle contain substances which repress the expression of mating ability when introduced into mature cells. When 5 x 10 /tm of immature cytoplasm were injected into mature cells, loss of mating ability occurred and it continued for more than 15 fissions after the injection. The effective substances are contained in the soluble fra...

(Prom the School of Tropical Medicine, Calcutta) In a previous paper it was observed by one ? us (Basu and Bose, 1941) that although the toxicity (LD/50) of 2-chloro-7-methoxy-5 (8c lethyl-amino-butyl) amino-acridine, in mice, Jas only slightly higher than that of 2-chloro~n}ethoxy-5 (8-diethyl-amino-iso-amyl) aminoacndine, the toxic effect of the former on cultures of Paramecium caudatum was f...

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...

positive transformant clones probed with the PcVenus sequence revealed that the injected DNA had become randomly inserted into the chromosome. Free linear monomers or multimers of injected DNA molecules as seen in P. primaurelia and P. tetraurelia were not evident even though the plasmid possessed extant telomeric repeats at its both extremities. We also cloned fragments containing the integrat...

The gram-negative bacterium Holospora obtusa is an endonuclear symbiont of Paramecium caudatum, which is incorporated into the host cells via the food vacuoles and infects their macronucleus exclusively, but never the micronucleus. Since these two kinds of nuclei originate from a fertilization nucleus, it is assumed that the macronucleus acquires a property necessary for it to be recognized by ...