scholarly journals Induction of autogamy by treatment with trypsin in Paramecium caudatum

1979 ◽  
Vol 35 (1) ◽  
pp. 177-184
Author(s):  
K. Mikami ◽  
S. Koizumi

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 conjugants indicate usually the same DNA content in both. The stock dm −13, heterozygous for mating type gene loci, showed the definite ratio of segregation to 2 mating types in clones derived from prematurely separated conjugants. Those results suggest that the prematurely separated cells usually undergo autogamy.

Genetics ◽  
1996 ◽  
Vol 144 (4) ◽  
pp. 1437-1444
Author(s):  
C Ian Robertson ◽  
Kirk A Bartholomew ◽  
Charles P Novotny ◽  
Robert C Ullrich

The Aα locus is one of four master regulatory loci that determine mating type and regulate sexual development in Schizophyllum commune. We have made a plasmid containing a URA1 gene disruption of the Aα Y1 gene. Y1 is the sole Aα gene in Aα1 strains. We used the plasmid construction to produce an Aα null (i.e., AαΔ) strain by replacing the genomic Y1 gene with URA1 in an Aα1 strain. To characterize the role of the Aα genes in the regulation of sexual development, we transformed various Aα Y and Z alleles into AαΔ strains and examined the acquired mating types and mating abilities of the transformants. These experiments demonstrate that the Aα Y gene is not essential for fungal viability and growth, that a solitary Z Aα mating-type gene does not itself activate development, that Aβ proteins are sufficient to activate the A developmental pathway in the absence of Aα proteins and confirm that Y and Z genes are the sole determinants of Aα mating type. The data from these experiments support and refine our model of the regulation of A-pathway events by Y and Z proteins.


1990 ◽  
Vol 10 (1) ◽  
pp. 409-412 ◽  
Author(s):  
G P Livi ◽  
J B Hicks ◽  
A J Klar

The silent mating-type genes (HML and HMR) of Saccharomyces cerevisiae are kept under negative transcriptional control by the trans-acting products of the four MAR/SIR loci. MAR/SIR gene mutations result in the simultaneous derepression of HML and HMR gene expression. The sum1-1 mutation was previously identified as an extragenic suppressor of mutations in MAR1 (SIR2) and MAR2 (SIR3). As assayed genetically, sum1-1 is capable of restoring repression of silent mating-type information in cells containing mar1 or mar2 null mutations. We show here that the mating-type phenotype associated with sum1-1 results from a dramatic reduction in the steady-state level of HML and HMR gene transcripts. At the same time, the sum1-1 mutation has no significant effect on the level of each of the four MAR/SIR mRNAs.


1979 ◽  
Vol 34 (2) ◽  
pp. 163-172 ◽  
Author(s):  
Yuuji Tsukii ◽  
Koichi Hiwatashi

SUMMARYThree methods of artificial induction of autogamy in Paramecium caudatum were described: (1) treatment with KCl+papain, (2) treatment with KCl and then with KCl + papain and (3) ordinary mating reaction and then treatment with papain. As expected, one-to-one segregation ratios were obtained in the progeny from the parents heterozygous for the two loci: mating type and lactate dehydrogenase. A high rate of autogamy is induced by method (1), but its use is restricted to only a few clones. Autogamy is also induced at a high rate by method (2), by which the induction is more stable. Autogamy is induced at a lower rate by method (3), but this method can be widely applied to every species of Paramecium which has complementary mating types. Some exautogamous progeny become completely sterile through successive autogamy. The cause of this sterility is discussed.


2015 ◽  
Vol 40 (1) ◽  
pp. 65-69
Author(s):  
Li-Shyang Chen ◽  
Chii-Dong Liu ◽  
Jwu-Guh Tsay ◽  
Ruey-Shayang Chen

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