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5976868 
Journal Article 
Induction of pseudo selfing and meiosis in Paramecium aurelia by formalin killed animals of opposite mating type 
Metz, CB 
1947 
1 
Journal of Experimental Zoology
ISSN: 0022-104X
EISSN: 1097-010X 
105 
1 
115-139 
English 
20238552 
BCI:BCI19472100023640 
P. aurelia variety 4 killed by appropriate treatment with formalin clump strongly and specifically with living animals of opposite mating type. The clumps of living and dead animals break down in 60 to 90 minutes releasing single living animals and pairs of living animals. These "pseudo selfing" pairs remain united for about 5 hrs. Union of fusion of these structures was never observed. Clones expanded from both members of "pseudo selfing" pairs were always of the same mating type. Pair members invariably underwent nuclear reorganization (presumably autogamy) if they were not separated prematurely. Comparison of "pseudo selfers" and normal conjugants from reaction mixtures made up at the same time showed that identical meiotic stages appeared simultaneously in "selfers" and conjugants. The nuclear reorganization was not dependent upon the "pseudo selfing" reaction, but could be induced specifically in isolated living animals of one type by formalin killed animals of opposite type. The studies suggest that meiosis, macronuclear breakdown, paroral cone formation and possibly other conjugation effects may be induced by interaction of mating type substances at the surface of the animals. The mechanics of "pseudo selfing" have not been investigated.