Phenotypic conversion of mating type specificity induced by transplantation of macronucleoplasm in<i>Paramecium caudatum</i>

Hori, Manabu; Takahashi, Mihoko

doi:10.1017/s0016672300032201

Cited by 10 publications

(6 citation statements)

References 16 publications

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“…Microinjection was performed by the method described by Hori & Takahashi (1994). Cells for the transplantation of cytoplasm or macronucleoplasm were deciliated with 5 % ethanol (Ogura, 1981) and embedded in mineral oil (Squibb & Sons).…”

Section: (Ii) Microinjectionmentioning

confidence: 99%

An unusual complementation in non-excitable mutants in Paramecium

2000

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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.

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Section: (Ii) Microinjectionmentioning

confidence: 99%

An unusual complementation in non-excitable mutants in Paramecium

2000

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“…All injected genome DNA were extracted according to the method of Blin and Stafford (1976) and dissolved with injection buffer (Koizumi and Kobayashi 1989). Microinjection was performed as previously described (Hori and Takahashi 1994). Cells were deciliated with 5% (v/v) ethanol (Ogura 1981) and embedded in mineral oil (Squibb & Sons, Inc., Princeton, NJ).…”

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confidence: 99%

Micronucleus‐Specific Bacterium Holospora elegans Irreversibly Enhances Stress Gene Expression of the Host Paramecium caudatum

Hori

Fujii

Fujishima

2008

J Eukaryotic Microbiology

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The bacterium Holospora is an endonuclear symbiont of the ciliate Paramecium. Previously, we reported that paramecia bearing the macronuclear-specific symbiont Holospora obtusa survived better than symbiont-free paramecia, even under high temperatures unsuitable for growth. The paramecia with symbionts expressed high levels of hsp70 mRNAs even at 25 degrees C, a usual growth temperature. We report herein that paramecia bearing the micronuclear-specific symbiont Holospora elegans also acquire the heat-shock resistance. Even after the removal of the bacteria from the hosts by treatment with penicillin, the resulting aposymbiotic paramecia nevertheless maintained their heat shock-resistant nature for over 1 yr. Like symbiotic paramecia, these aposymbiotic paramecia also expressed high levels of both hsp60 and hsp70 mRNAs even at 25 degrees C. Moreover, analysis by fluorescent in situ hybridization with a probe specific for Holospora 16S rRNA revealed that the 16S rRNA of H. elegans was expressed around the nucleoli of the macronucleus in the aposymbiotic cells. This result suggests the possible transfer of Holospora genomic DNA from the micronucleus into the macronucleus in symbiotic paramecia. Perhaps this exogenous DNA could trigger the aposymbiotic paramecia to induce a stress response, inducing higher expression of Hsp60 and Hsp70, and thus conferring heat-shock resistance.

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“…The GFP fusion constructs of each gene were injected into the macronuclei of immature cells immediately after autogamy. Microinjection was performed as described in an earlier report (Hori and Takahashi 1994). The transformants were cultivated at 25°C for at least 2 wk.…”

Section: Expression Vector For Gfp Fusion Proteins and Transformationmentioning

confidence: 99%

Roles of Adenylate Cyclases in Ciliary Responses of Paramecium to Mechanical Stimulation

Kawano

Tominaga

Ishida

et al. 2020

J Eukaryotic Microbiology

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Paramecium shows rapid forward swimming due to increased beat frequency of cilia in normal (forward swimming) direction in response to various kinds of stimuli applied to the cell surface that cause K+‐outflow accompanied by a membrane hyperpolarization. Some adenylate cyclases are known to be functional K+ channels in the membrane. Using gene‐specific knockdown methods, we examined nine paralogues of adenylate cyclases in P. tetraurelia to ascertain whether and how they are involved in the mechanical stimulus‐induced hyperpolarization‐coupled acceleration of forward swimming. Results demonstrated that knockdown of the adenylate cyclase 1 (ac1)‐gene and 2 (ac2)‐gene inhibited the acceleration of forward swimming in response to mechanical stimulation of the cell, whereas that spared the acceleration response to external application of 8‐Br‐cAMP and dilution of extracellular [K+] induced hyperpolarization. Electrophysiological examination of the knockdown cells revealed that the hyperpolarization‐activated inward K+ current is smaller than that of a normal cell. Our results suggest that AC1 and AC2 are involved in the mechanical stimulus‐induced acceleration of ciliary beat in Paramecium.

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Phenotypic conversion of mating type specificity induced by transplantation of macronucleoplasm inParamecium caudatum

Cited by 10 publications

References 16 publications

An unusual complementation in non-excitable mutants in Paramecium

An unusual complementation in non-excitable mutants in Paramecium

Micronucleus‐Specific Bacterium Holospora elegans Irreversibly Enhances Stress Gene Expression of the Host Paramecium caudatum

Roles of Adenylate Cyclases in Ciliary Responses of Paramecium to Mechanical Stimulation

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