| Delayed degradation of parental macronuclear DNA in programmed nuclear death of Paramecium caudatum. | |
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MedLine Citation:
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PMID: 15354289 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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In the ciliated protozoan Paramecium caudatum, a parental macronucleus that is fragmented into some 40-50 pieces during conjugation does not degenerate immediately, but persists until the eighth cell cycle after conjugation. Here we demonstrate that the initiation of the parental macronuclear degeneration occurs at about the fifth cell cycle. The size of parental macronuclear fragments continued to increase between the first and fourth cell cycle, but gradually decreased thereafter. By contrast, a new macronucleus grew and reached a maximum size by the fourth cell cycle, suggesting that the new macronucleus matured by that stage. Southern blot analysis revealed that parental macronuclear DNA was degraded at about the fifth cell cycle. The degradation was supported by acridine orange staining, indicating degeneration of the macronuclear fragments. Prior to the degradation, the fragments once attached to the new macronucleus were subsequently liberated from it. These observations lead us to conclude that once a new macronucleus has been fully formed by the fourth cell cycle, the parental macronuclear fragments are destined to degenerate, probably through direction by new macronucleus. Considering the long persistence of the parental macronucleus during the early cell cycles after conjugation, the macronuclear fragments might function in the maturation of the imperfect new macronucleus. Two possible functions, a gene dosage compensation and adjustment of ploidy level, are discussed. |
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Authors:
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Naomi Kimura; Kazuyuki Mikami; Hiroshi Endoh |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Genesis (New York, N.Y. : 2000) Volume: 40 ISSN: 1526-954X ISO Abbreviation: Genesis Publication Date: 2004 Sep |
Date Detail:
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Created Date: 2004-09-08 Completed Date: 2005-02-22 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 100931242 Medline TA: Genesis Country: United States |
Other Details:
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Languages: eng Pagination: 15-21 Citation Subset: IM |
Copyright Information:
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Copyright 2004 Wiley-Liss, Inc. |
Affiliation:
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Department of Biology, Faculty of Science, Kanazawa University, Kanazawa, Japan. naomi@ge.kanazawa-u.ac.jp |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Apoptosis Conjugation, Genetic DNA, Protozoan / genetics* Humans Macronucleus / genetics, ultrastructure Paramecium caudatum / cytology*, genetics*, physiology |
| Chemical | |
Reg. No./Substance:
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0/DNA, Protozoan |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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