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Chen PF, Singhal S, Bushyhead D, Broder-Fingert S, Wolfe J. Colchicine-induced degeneration of the micronucleus during conjugation in Tetrahymena. Biol Open 2014; 3:353-61. [PMID: 24728958 PMCID: PMC4021357 DOI: 10.1242/bio.20147708] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
One of the most dramatic examples of nuclear morphogenesis occurs during conjugation in Tetrahymena when the micronucleus elongates to a size longer than the cell itself. After contraction to a spherical shape, the nucleus moves directly to chromosome separation in the first meiotic division. Here we investigate the consequences of interrupting the elongation process. Colchicine, a microtubule inhibitor, caused retraction of elongated structures. With time, cells began to lose their micronuclei, and by five hours more than half of the paired cells had at least one cell missing a micronucleus. After reversing the colchicine block, existing micronuclei did not undergo elongation again, nor did meiosis occur. These observations indicate that micronuclear elongation is critical to subsequent meiotic division. Further, nuclear elimination occurs, which could be due to meiotic failure or possibly a problem downstream from meiosis. An analysis of the process of colchicine-induced micronuclear degeneration indicated that it was regulated by a caspase-dependent mechanism, characteristic of apoptosis, and then resorbed by a lysosome-dependent autophagic mechanism. Amicronucleate cells failed to grow when returned to nutrient medium, likely because of a lesion in the post-conjugation reconstruction of a functioning oral apparatus. The ease by which a large number of nuclei are induced to "self-destruct" may make this system useful in investigating the link between colchicine treatment and nuclear death in Tetrahymena, and in investigating how nuclear death could be regulated in living cells more generally. Finally, we note that this phenomenon might relate to the evolution of amicronucleate species of Tetrahymena.
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Affiliation(s)
- Pin-Fang Chen
- Present address: Department of Genetics and Developmental Biology, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Sita Singhal
- Present address: Internal Medicine Residency Program, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Daniel Bushyhead
- Present address: School of Medicine, University of Washington, Seattle, WA 98195, USA
| | - Sarabeth Broder-Fingert
- Present address: Department of Pediatrics, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Jason Wolfe
- Department of Biology, Wesleyan University, Middletown, CT 06459, USA Present address: Department of Genetics and Developmental Biology, University of Connecticut Health Center, Farmington, CT 06030, USA. Present address: Internal Medicine Residency Program, University of Connecticut Health Center, Farmington, CT 06030, USA. Present address: School of Medicine, University of Washington, Seattle, WA 98195, USA. Present address: Department of Pediatrics, Massachusetts General Hospital, Boston, MA 02114, USA.
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NANNEY DL, COOPER LE, SIMON EM, WHITT GS. Isozymic Characterization of Three Mating Groups of the Tetrahymena pyriformis complex*. ACTA ACUST UNITED AC 2007. [DOI: 10.1111/j.1550-7408.1980.tb05397.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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TAKAHASHI TADAO. Reorganization in Amicronucleates with Defective Mouth of the CiliatePseudourostyla levis1. ACTA ACUST UNITED AC 2007. [DOI: 10.1111/j.1550-7408.1988.tb04094.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Abstract
The author describes the serendipitous discovery, conception, development, and history of Nissenbaum's Fixative while an undergraduate biology major in the early 1950s. The subsequent uses, applications, and modifications over the past forty-seven years are also described. Some of the modifications omitted from his short original paper are mentioned. Highlights of his subsequent career in the field of medicine are noted.
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Affiliation(s)
- G Nissenbaum
- Department of Medicine, Jersey City Medical Center, New Jersey 07304, USA.
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Kaney AR, Speare VJ. A genetic screen for vegetative gene expression in the micronucleus of Tetrahymena thermophila. THE JOURNAL OF PROTOZOOLOGY 1992; 39:323-8. [PMID: 1578407 DOI: 10.1111/j.1550-7408.1992.tb01323.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The presence of a micronucleus with at least a small portion of the micronuclear genome appears to be indispensable for vegetative viability in the ciliate Tetrahymena thermophila. A genetic screen was devised to detect evidence of expression of essential genes in the vegetative micronucleus by identification of thermosensitive-lethal mutations expressed in the absence of nuclear reorganization. Although control experiments demonstrated the efficacy of the method for induction and recovery of thermosensitive lethal mutations in micronuclear genes, no expressed mutations were recovered in the absence of nuclear reorganization. This finding complements the existing lack of convincing biochemical evidence for gene expression in the vegetative micronucleus and suggests that the essential function may involve genomic DNA sequences for which thermosensitive mutant alleles are not recoverable, or perhaps a non-genomic component of the organelle.
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Affiliation(s)
- A R Kaney
- Department of Biology, Bryn Mawr College, Pennsylvania 19010
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Takahashi T, Suhama M. Regeneration of amicronucleate fragments in the hypotrichous ciliate Pseudourostyla levis. Eur J Protistol 1991. [DOI: 10.1016/s0932-4739(11)80152-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Mikami K, Kuhlmann HW, Heckmann K. Is the initiation of macronuclear DNA synthesis in Euplotes dependent on micronuclear functions? Exp Cell Res 1985; 161:445-59. [PMID: 3933990 DOI: 10.1016/0014-4827(85)90100-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
To determine whether the micronucleus makes essential contributions during asexual reproduction, observations were made on cells of Euplotes octocarinatus from which the micronucleus had been removed with a micropipette. Most cells underwent one postenucleation division, then became arrested in macronuclear G1, slowed down in food uptake, developed macronuclear deformations, and finally died. Such cells could be rescued if a micronucleus was reimplanted before macronuclear deformations had developed. When provided with a new micronucleus, cells initiated macronuclear DNA synthesis about 12-16 h later. The data suggest that the micronucleus is involved in the control of the cell's transition from macronuclear G1 to S, and a model is proposed which postulates that in Euplotes macronuclear DNA synthesis is initiated when a micronucleus-encoded "initiator protein" has accumulated to a critical amount.
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Karrer K, Stein-Gavens S, Allitto BA. Micronucleus-specific DNA sequences in an amicronucleate mutant of Tetrahymena. Dev Biol 1984; 105:121-9. [PMID: 6468755 DOI: 10.1016/0012-1606(84)90267-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
DNA from the amicronucleate Tetrahymena cell line BI3840 was probed for DNA sequences which are limited to the micronucleus in wild-type cells. Four micronucleus-specific DNA sequences were not detectable in DNA from the amicronucleate cell line. Two of the six micronucleus-specific DNA sequences tested hybridized to DNA from amicronucleate cells. Both the number of fragments homologous to these sequences and the intensity of hybridization were reduced in the DNA from the amicronucleate cells relative to DNA from a wild-type cell line, indicating that less than one micronucleus equivalent of the micronucleus-specific DNA sequences was retained in the amicronucleate cell line. Thus many micronucleus-specific DNA sequences were eliminated from the developing macronucleus of BI3840 as they are in wild-type cells, but in at least two cases the elimination was incomplete. In situ hybridization suggested that the DNA sequences which are limited to the micronucleus in wild-type cells are present in the macronucleus of the amicronucleate cell line. Southern blots of DNA from the amicronucleate cell line were also probed with DNA sequences which are retained in the macronucleus. At least two types of genome rearrangements occurred in the BI3840 macronucleus as they do in wild-type cells. No spurious rearrangements were observed.
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Abstract
A stable amicronucleate strain of Tetrahymena thermophila was isolated following nitrosoguanidine mutagenesis. The mutant has the same growth rate and viability as the micronucleate parent strain, and has no micronucleus detectable by chromatin-specific staining in vegetative growth or during conjugation. The mutant pairs with normal efficiency with cells of complementary mating type. Matings of the mutant with aneuploid strains which lose their micronucleus during meiosis produced cell pairs yielding one viable and one inviable cell. The mutant receives a micronucleus from a normal mating partner, but this micronucleus is lost by the mutant cells within two hundred generations.
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Zur funktion der ciliaten-riesenchromosomen: Nachweis von RNS-polymerase in den polytänen chromosomen der makronukleusanlage von Stylonychia mytilus. ACTA ACUST UNITED AC 1981. [DOI: 10.1016/s0003-9365(81)80017-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Mikami K. Stomatogenesis during sexual and asexual reproduction in an amicronucleate strain of Paramecium caudatum. THE JOURNAL OF EXPERIMENTAL ZOOLOGY 1979; 208:121-8. [PMID: 469476 DOI: 10.1002/jez.1402080113] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Amicronucleate cells of Paramecium caudatum, whose micronuclei have been artifically removed by micropipetting, are characterized by the appearance of a deciliated area at the posterior part of the buccal opening. These cells form food vacuoles at a slightly lower rate than micronucleate cells. Their mean interfission time is longer than that in micronucleates. The exconjugants of amicronucleate cells can not form food vacuoles and eventually die witout fission, though conjugation proceeds normally in them as well as in their micronucleate mate. The oral apparatus of amicronucleate exconjugants seems to be shallower than that of micronucleates. The membranellar cilia, therefore, can be seen through the buccal overture by scanning electron microscope. The results obtained from the cross of micronucleate and amicronucleate strains and from the induction of autogamy in amicronucleate strains suggest that the micronucleus has a primary role in developing the normal oral apparatus after nuclear reorganization.
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Allen SL. Genomic exclusion: a rapid means for inducing homozygous diploid lines in Tetrahymena pyriformis, syngen 1. Science 1967; 155:575-7. [PMID: 6015874 DOI: 10.1126/science.155.3762.575] [Citation(s) in RCA: 94] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Genomic exclusion is an abnormal form of conjugation occurring between cells with defective micronuclei and normal cells with diploid micronuclei. The progeny are heterocaryons; each cell has an old macronucleus but a new diploid micronucleus derived from one meiotic product of the normal mate. Such cells express genes found in the old macronucleus, are sexually mature, and can be specifically selected. When inbred, they give rise to lines genetically homozygous at all known loci.
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