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Macronuclear Duplication in the Ciliated Protozoan Euplotes

The ribbon-like macronucleus of Euplotes eurystomus pinches in half amitotically at each cell division. Several hours before the actual division two lightly staining duplication bands (reorganization bands) appear at the ends of the nucleus and approach each other slowly, finally meeting near the mi...

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Detalles Bibliográficos
Autor principal: Gall, Joseph G.
Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 1959
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2224660/
https://www.ncbi.nlm.nih.gov/pubmed/13654451
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author Gall, Joseph G.
author_facet Gall, Joseph G.
author_sort Gall, Joseph G.
collection PubMed
description The ribbon-like macronucleus of Euplotes eurystomus pinches in half amitotically at each cell division. Several hours before the actual division two lightly staining duplication bands (reorganization bands) appear at the ends of the nucleus and approach each other slowly, finally meeting near the middle. Distal to the bands, that is, in regions through which the bands have already passed, the concentration of DNA (Feulgen) and "histone" (alkaline fast green) is greater than in the central zone. These facts suggest the hypothesis that DNA-histone synthesis takes place in a sequential fashion starting at the tips of the nucleus and proceeding to the middle. That this hypothesis is correct is shown by autoradiographic and photometric observations. Tritium-labelled thymidine is incorporated only in a limited region immediately distal to the bands. The average amount of Feulgen dye bound by the nucleus rises as the duplication bands approach each other, and is double the presynthesis value by the time the bands meet. A similar rise in the alkaline fast green dye is seen in duplicating nuclei, although no completely post-synthesis values were obtained in this study. The quantitative data are consistent with the assumption that the macronucleus contains a number of DNA-histone "units," presumably chromosomes, each of which duplicates once and only once.
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spelling pubmed-22246602008-05-01 Macronuclear Duplication in the Ciliated Protozoan Euplotes Gall, Joseph G. J Biophys Biochem Cytol Article The ribbon-like macronucleus of Euplotes eurystomus pinches in half amitotically at each cell division. Several hours before the actual division two lightly staining duplication bands (reorganization bands) appear at the ends of the nucleus and approach each other slowly, finally meeting near the middle. Distal to the bands, that is, in regions through which the bands have already passed, the concentration of DNA (Feulgen) and "histone" (alkaline fast green) is greater than in the central zone. These facts suggest the hypothesis that DNA-histone synthesis takes place in a sequential fashion starting at the tips of the nucleus and proceeding to the middle. That this hypothesis is correct is shown by autoradiographic and photometric observations. Tritium-labelled thymidine is incorporated only in a limited region immediately distal to the bands. The average amount of Feulgen dye bound by the nucleus rises as the duplication bands approach each other, and is double the presynthesis value by the time the bands meet. A similar rise in the alkaline fast green dye is seen in duplicating nuclei, although no completely post-synthesis values were obtained in this study. The quantitative data are consistent with the assumption that the macronucleus contains a number of DNA-histone "units," presumably chromosomes, each of which duplicates once and only once. The Rockefeller University Press 1959-03-25 /pmc/articles/PMC2224660/ /pubmed/13654451 Text en Copyright © Copyright, 1959, by The Rockefeller Institute
spellingShingle Article
Gall, Joseph G.
Macronuclear Duplication in the Ciliated Protozoan Euplotes
title Macronuclear Duplication in the Ciliated Protozoan Euplotes
title_full Macronuclear Duplication in the Ciliated Protozoan Euplotes
title_fullStr Macronuclear Duplication in the Ciliated Protozoan Euplotes
title_full_unstemmed Macronuclear Duplication in the Ciliated Protozoan Euplotes
title_short Macronuclear Duplication in the Ciliated Protozoan Euplotes
title_sort macronuclear duplication in the ciliated protozoan euplotes
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2224660/
https://www.ncbi.nlm.nih.gov/pubmed/13654451
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