MUTANTS WITH ALTERED Ca2+-CHANNEL PROPERTIES IN PARAMECIUM TETRAURELIA: ISOLATION, CHARACTERIZATION AND GENETIC ANALYSIS

Genetics ◽  
1984 ◽  
Vol 108 (3) ◽  
pp. 545-558
Author(s):  
Robert D Hinrichsen ◽  
Yoshiro Saimi ◽  
Ching Kung
Keyword(s):  
Genetic Analysis ◽  
Complementation Group ◽  
Phenotypic Change ◽  
Paramecium Tetraurelia ◽  
Wild Type ◽  
Cytoplasmic Factor ◽  
Wild Type Phenotype ◽  
Channel Properties ◽  
Ca2 Channels ◽  
F1 Generation

ABSTRACT Dancers are a group of mutants in Paramecium tetraurelia whose Ca2+ current inactivates poorly and are likely to be defective in the structure of their Ca2+ channels. These mutants show prolonged backward swimming in response to K+ and Ba2+ in the medium and were selected by this property in a galvanotactic trough. The dancer mutants are semidominant, and all isolated mutants belong to one complementation group; they are not allelic to any of the previously isolated behavioral mutants of P. tetraurelia. The phenotypic change from the homozygous parent to heterozygous F1 generation takes three to five fissions. There is no evidence of a cytoplasmic factor capable of converting the dancer to the wild-type phenotype, as has been demonstrated in the mutants pawn and cnr. We suggest that the dancer locus is a structural gene for the Ca2+ channel.

scholarly journals Gene expression and phenotypic change in Paramecium tetraurelia exconjugants

1976 ◽  
Vol 27 (2) ◽  
pp. 123-134 ◽  
Author(s):  
James D. Berger
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Phenotypic Change ◽  
Paramecium Tetraurelia ◽  
Wild Type Allele ◽  
Wild Type ◽  
Cytoplasmic Factor ◽  
Cell Cycles ◽  
Type Allele ◽  
Parental Phenotype

SUMMARYA study of the patterns of phenotypic change in exconjugants using the recessive behavioural mutant pawn (pwA) and its wild-type allele shows that both cytoplasmic and nuclear factors contribute to phenomic lag. Following loss of the wild-type allele from the macronucleus, phenomic lag lasts for 6–11 cell cycles in various sublines of a single clone. Inherited cytoplasmic material is estimated to be responsible for phenomic lag of no more than 5–6 cell cycles. Longer persistence of the parental phenotype is due to continued gene activity in macronuclear fragments carrying the wild-type allele. Genes in fragments remain active and can result in maintenance of the parental phenotype as long as fragments are present (up to 11 cell cycles).Phenomic lag in the other direction, from pawn to wild type, varies from 0 to 2 cell cycles. The major cytoplasmic factor involved is the amount of wild-type material acquired from the mate during conjugation. Extensive cytoplasmic exchange often occurs during normal conjugation and can lead to change of phenotype as early as the first meiotic division. Phenotypic change due to gene expression in macronuclear anlagen brings about phenotypic change near the end of the first cell cycle in +/+ cells and about a cell cycle later in heterozygotes.

scholarly journals GENETIC ANALYSIS OF MUTANTS WITH A REDUCED Ca2+-DEPENDENT K+ CURRENT IN PARAMECIUM TETRAURELIA

Genetics ◽  
1985 ◽  
Vol 111 (3) ◽  
pp. 433-445
Author(s):  
Robert D Hinrichsen ◽  
Ed Amberger ◽  
Yoshiro Saimi ◽  
Anthony Burgess-Cassler ◽  
Ching Kung
Keyword(s):  
Genetic Analysis ◽  
High Speed ◽  
Behavioral Responses ◽  
Supernatant Fraction ◽  
Paramecium Tetraurelia ◽  
Wild Type ◽  
Wild Type Phenotype ◽  
K Current ◽  
High Speed Supernatant ◽  
K Currents

ABSTRACT Two mutants of Paramecium tetraurelia with greatly reduced Ca2+-dependent K+ currents have been isolated and genetically analyzed. These mutants, designated pantophobiac, give much stronger behavioral responses to all stimuli than do wild-type cells. Under voltage clamp, the Ca2+-dependent K+ current is almost completely eliminated in these mutants, whereas the Ca2+ current is normal. The two mutants, pntA and pntB, are recessive and unlinked to each other. pntA is not allelic to several other ion-channel mutants of P. tetraurelia. The microinjection of a high-speed supernatant fraction of wild-type cytoplasm into either pantophobiac mutant caused a temporary restoration to the wild-type phenotype.

scholarly journals Phenotypic and Genetic Analysis of “Chameleon,” a Paramecium Mutant With an Enhanced Sensitivity to Magnesium

Genetics ◽  
1997 ◽  
Vol 146 (3) ◽  
pp. 871-880
Author(s):  
Robin R Preston ◽  
Jocelyn A Hammond
Keyword(s):  
Genetic Analysis ◽  
Single Locus ◽  
Behavioral Analysis ◽  
Paramecium Tetraurelia ◽  
Wild Type ◽  
Ion Conductance ◽  
Membrane Excitation ◽  
Enhanced Sensitivity ◽  
Electrophysiological Analysis ◽  
Mutant Strains

Three mutant strains of Paramecium tetraurelia with an enhanced sensitivity to magnesium have been isolated. These new “Chameleon” mutants result from partial- or codominant mutations at a single locus, Cha. Whereas the wild type responded to 5 mm Mg2+ by swimming backward for 10–15 sec, Cha mutants responded with ∼30 sec backward swimming. Electrophysiological analysis suggested that this behavior may be caused by slowing in the rate at which a Mg2+-specific ion conductance deactivates following membrane excitation. This would be consistent with an observed increase in the sensitivity of Cha mutants to nickel poisoning, since Ni2+ is also able to enter the cell via this pathway. More extensive behavioral analysis showed that Cha cells also overresponded to Na+, but there was no evidence for a defect in intracellular Ca2+ homeostasis that might account for a simultaneous enhancement of both the Mg2+ and Na+ conductances. The possibility that the Cha locus may encode a specific regulator of the Mg2+- and Na+-permeabilities is considered.

scholarly journals Macronuclear transformation with specific DNA fragments controls the content of the new macronuclear genome in Paramecium tetraurelia.

1991 ◽  
Vol 11 (2) ◽  
pp. 1133-1137 ◽  
Author(s):  
Y You ◽  
K Aufderheide ◽  
J Morand ◽  
K Rodkey ◽  
J Forney
Keyword(s):  
Cell Line ◽  
Dna Sequences ◽  
Mutant Cell ◽  
Restriction Pattern ◽  
Paramecium Tetraurelia ◽  
Wild Type ◽  
Coding Region ◽  
Cytoplasmic Factor ◽  
In The Wild ◽  
Dna Restriction

A previously isolated mutant cell line called d48 contains a complete copy of the A surface antigen gene in the micronuclear genome, but the gene is not incorporated into the macronucleus. Previous experiments have shown that a cytoplasmic factor made in the wild-type macronucleus can rescue the mutant. Recently, S. Koizumi and S. Kobayashi (Mol. Cell. Biol. 9:4398-4401, 1989) observed that injection of a plasmid containing the A gene into the d48 macronucleus rescued the cell line after autogamy. It is shown here that an 8.8-kb EcoRI fragment containing only a portion of the A gene coding region is sufficient for the rescue of d48. The inability of other A gene fragments to rescue the mutant shows that this effect is dependent upon specific Paramecium DNA sequences. Rescue results in restoration of the wild-type DNA restriction pattern in the macronucleus. These results are consistent with a model in which the macronuclear A locus normally makes an additional gene product that is required for correct processing of the micronuclear copy of the A gene.

scholarly journals Macronuclear transformation with specific DNA fragments controls the content of the new macronuclear genome in Paramecium tetraurelia

1991 ◽  
Vol 11 (2) ◽  
pp. 1133-1137
Author(s):  
Y You ◽  
K Aufderheide ◽  
J Morand ◽  
K Rodkey ◽  
J Forney
Keyword(s):  
Cell Line ◽  
Dna Sequences ◽  
Mutant Cell ◽  
Restriction Pattern ◽  
Paramecium Tetraurelia ◽  
Wild Type ◽  
Coding Region ◽  
Cytoplasmic Factor ◽  
In The Wild ◽  
Dna Restriction

A previously isolated mutant cell line called d48 contains a complete copy of the A surface antigen gene in the micronuclear genome, but the gene is not incorporated into the macronucleus. Previous experiments have shown that a cytoplasmic factor made in the wild-type macronucleus can rescue the mutant. Recently, S. Koizumi and S. Kobayashi (Mol. Cell. Biol. 9:4398-4401, 1989) observed that injection of a plasmid containing the A gene into the d48 macronucleus rescued the cell line after autogamy. It is shown here that an 8.8-kb EcoRI fragment containing only a portion of the A gene coding region is sufficient for the rescue of d48. The inability of other A gene fragments to rescue the mutant shows that this effect is dependent upon specific Paramecium DNA sequences. Rescue results in restoration of the wild-type DNA restriction pattern in the macronucleus. These results are consistent with a model in which the macronuclear A locus normally makes an additional gene product that is required for correct processing of the micronuclear copy of the A gene.

scholarly journals An unusual complementation in non-excitable mutants in Paramecium

2000 ◽  
Vol 76 (2) ◽  
pp. 125-133 ◽  
Author(s):  
ATSUSHI MATSUDA ◽  
YOSHIRO SAIMI ◽  
MIHOKO TAKAHASHI
Keyword(s):  
Genetic Relationship ◽  
The Other ◽  
Unusual Feature ◽  
Marker Genes ◽  
Paramecium Tetraurelia ◽  
Wild Type ◽  
Other Hand ◽  
Wild Type Phenotype ◽  
Allelic Interaction

A non-excitable behavioural mutant, d4-662, was previously characterized as the fourth pawn locus mutant pwD in Paramecium tetraurelia. We now provide data demonstrating that d4-662 is in fact controlled by a pwB allele that has the unusual feature of complementing other pwB alleles in heterozygous F1 progeny. Neither the cytoplasm nor the nucleoplasm of d4-662 cured the mutational defects of pwB and in the reverse combination of d4-662 and pwB, the result was the same. On the other hand, pwA, another non-excitable mutant, was cured upon cross-injection with d4-662 and mutants carrying trichocyst non-discharge marker genes were also cured. This evidence suggests that d4-662 is a new mutant belonging to pwB, and would be better designated as pwB662. Extensive crossbreeding analyses, however, showed an unusual genetic relationship between d4-662 and pwB (pwB95 or pwB96). When d4-662 was crossed with pwB mutants, many progeny expressing wild-type phenotype or mixed clones of wild-type and pawn cells were obtained in the F1. Less than 12·5% expressed the pawn phenotype. The appearance of wild-type progeny in this F1 strongly suggests that an inter-allelic interaction between pwB662 and other pwB alleles may occur during development of the macronucleus.

scholarly journals Genetic analysis of axonemal mutants in Paramecium tetraurelia defective in their response to calcium

1984 ◽  
Vol 43 (1) ◽  
pp. 11-20 ◽  
Author(s):  
Robert D. Hinrichsen ◽  
Ching Kung
Keyword(s):  
Genetic Analysis ◽  
Elevated Temperatures ◽  
Complementation Group ◽  
Paramecium Tetraurelia ◽  
Genetic Analyses ◽  
Complementation Groups

SUMMARYSix axonemal mutants of Paramecium tetraurelia have been isolated that are unable to respond properly to calcium. The mutants, designated atalantas, cannot swim backward when stimulated by ions or heat. Genetic analyses reveal that all six mutants are recessive and fall into four complementation groups. Three of the mutants in one complementation group are phenotypically non-leaky, one is leaky and two are extremely leaky, only displaying their phenotypes at elevated temperatures. The complete mutants, ataA, are also abnormal in their forward swimming. This abnormality co-segregates with the inability to swim backward. ataA1 is not allelic to several membrane mutants of P. tetraurelia.

scholarly journals Restoration of membrane excitability in a behavioral mutant of Paramecium caudatum during conjugation and by microinjection of wild-type cytoplasm.

1980 ◽  
Vol 84 (2) ◽  
pp. 476-480 ◽  
Author(s):  
K Hiwatashi ◽  
N Haga ◽  
M Takahashi
Keyword(s):  
Membrane Fluidity ◽  
Phenotypic Change ◽  
Paramecium Caudatum ◽  
Wild Type ◽  
Membrane Excitability ◽  
Wild Type Phenotype ◽  
In Cells

When cells of the behavioral mutant cnrC of Paramecium caudatum were mated with the wild type, phenotype change from CNR (no backward swinning) to wild type in the cnrC mate occurred immediately after the formation of tight pairs. No change of phenotype occurred when cells of cnrA or cnrB were mated with wild type. Phenotypic change from CNR to wild type in cells of cnrC was also induced by microinjection of wild-type cytoplasm. Microinjection of wild-type cytoplasm induced no change in cells of cnrA or cnrB. Phenotypic change in the cnrC mate during conjugation can be explained by cytoplasmic exchange during conjugation, though transfer of membrane sites for excitability through membrane fluidity cannot be ruled out.

scholarly journals Loss of a Fragile Chromosome Region leads to the Screwy Phenotype in Paramecium tetraurelia

Genes ◽  
2019 ◽  
Vol 10 (7) ◽  
pp. 513
Author(s):  
Irina Nekrasova ◽  
Vera Nikitashina ◽  
Simran Bhullar ◽  
Olivier Arnaiz ◽  
Deepankar P. Singh ◽  
...  
Keyword(s):  
Zinc Finger ◽  
Cell Shape ◽  
Reference Strain ◽  
Chromosome Region ◽  
Single Gene ◽  
Paramecium Tetraurelia ◽  
Wild Type ◽  
Wild Type Phenotype ◽  
Phenotype Switch ◽  
Spinning Top

A conspicuous cell-shape phenotype known as “screwy” was reported to result from mutations at two or three uncharacterized loci in the ciliate Paramecium tetraurelia. Here, we describe a new screwy mutation, Spinning Top, which appeared spontaneously in the cross of an unrelated mutant with reference strain 51. The macronuclear (MAC) genome of the Spinning Top mutant is shown to lack a ~28.5-kb segment containing 18 genes at the end of one chromosome, which appears to result from a collinear deletion in the micronuclear (MIC) genome. We tested several candidate genes from the deleted locus by dsRNA-induced silencing in wild-type cells, and identified a single gene responsible for the phenotype. This gene, named Spade, encodes a 566-aa glutamine-rich protein with a C2HC zinc finger. Its silencing leads to a fast phenotype switch during vegetative growth, but cells recover a wild-type phenotype only 5–6 divisions after silencing is stopped. We analyzed 5 independently-obtained mutant alleles of the Sc1 locus, and concluded that all of them also lack the Spade gene and a number of neighboring genes in the MAC and MIC genomes. Mapping of the MAC deletion breakpoints revealed two different positions among the 5 alleles, both of which differ from the Spinning Top breakpoint. These results suggest that this MIC chromosome region is intrinsically unstable in strain 51.

scholarly journals Permanent rescue of a non-Mendelian mutation of Paramecium by microinjection of specific DNA sequences.

Genetics ◽  
1991 ◽  
Vol 129 (3) ◽  
pp. 727-734
Author(s):  
H Jessop-Murray ◽  
L D Martin ◽  
D Gilley ◽  
J R Preer ◽  
B Polisky
Keyword(s):  
Dna Sequences ◽  
Transcriptional Control ◽  
Molecular Mechanisms ◽  
Large Deletion ◽  
Paramecium Tetraurelia ◽  
Wild Type ◽  
Cytoplasmic Factor ◽  
Gene Copies ◽  
Unusual Phenomenon ◽  
Small Stable Rna

Abstract The mutant Paramecium tetraurelia cell line d48 is unable to express the serotype A protein on its surface. Although the A gene is intact in the micronuclei of d48, the A gene copies in the macronucleus contain a large deletion eliminating virtually the entire coding sequence. Previous studies showed that microinjection of a plasmid containing the entire A gene into the macronucleus of d48 permanently restored A expression after autogamy. Together with other data, this result suggests that in wild type cells the A gene in the old macronucleus ensures the presence of a cytoplasmic factor that prevents A gene deletions at autogamy. In d48, where there are few, if any copies of the intact A gene in the old macronucleus, deletions occur during macronuclear formation. To elucidate the specific molecular mechanisms involved in this unusual phenomenon, we attempted to define the region(s) of the A gene necessary for rescuing d48. We show that microinjection of a 4.5-kb internal A gene fragment is sufficient for proper processing at autogamy and leads to permanent rescue of d48; i.e., the rescued strain is indistinguishable from wild type. Thus, rescue of d48 does not require upstream transcriptional control sequences, intact A mRNA or A serotype protein. We also show that various fragments of the A gene have the ability to rescue d48 to different extents, some being more efficient than others. We find no evidence to suggest that the A gene gives rise to a small stable RNA that might act as or encode a cytoplasmic factor. Molecular mechanisms that may be involved in the rescue of d48 are discussed.

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