Cargando…

Characterization of cytoplasmic and nuclear genomes in the colorless alga Polytoma. I. Ultrastructural analysis of organelles

Electron microscope studies have been made on the fine structure of the colorless biflagellate, Polytoma obtusum, with main emphasis on the structural organization of the mitochondria and the leucoplast. Both organelles have been demonstrated to contain DNA aggregates as well as ribosomal particles...

Descripción completa

Detalles Bibliográficos
Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 1976
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2109689/
https://www.ncbi.nlm.nih.gov/pubmed/177431
_version_ 1782139370682187776
collection PubMed
description Electron microscope studies have been made on the fine structure of the colorless biflagellate, Polytoma obtusum, with main emphasis on the structural organization of the mitochondria and the leucoplast. Both organelles have been demonstrated to contain DNA aggregates as well as ribosomal particles within their matrix material. Reconstructions from serial showed that (a) the mitochondria were highly convoluted and irregular in shape and size, and (b) the leucoplast was a single cup- shaped entity, with large starch grains, localized at the posterior end, and multiple sites of DNA aggregates. The starch-containing compartments appeared to be interconnected by narrow tubular or sheetlike bridges. Cytoplasmic invaginations into the plastid, often containing mitochondria, were of frequent occurrence, and membranes of mitochondria and the leucoplast appeared to be closely apposed. Membranes elements, both sheetlike and vesicular, were also present in the matrix. The Polytoma leucoplast was, in certain respects, morphologically similar to the plastids of various photosynthetic mutants of Chlamydomonas, most of which show Menedelian segregation. It is suggested that Polytoma arose from a Chlamydomonas-like ancestor, possibly through combined mutational processess of both chloroplast and nuclear genomes. Since Polytoma leucoplasts contain both DNA and ribosomal particles, it is probable that these organelles still possess semiautonomy and limited ability for protein synthesis.
format Text
id pubmed-2109689
institution National Center for Biotechnology Information
language English
publishDate 1976
publisher The Rockefeller University Press
record_format MEDLINE/PubMed
spelling pubmed-21096892008-05-01 Characterization of cytoplasmic and nuclear genomes in the colorless alga Polytoma. I. Ultrastructural analysis of organelles J Cell Biol Articles Electron microscope studies have been made on the fine structure of the colorless biflagellate, Polytoma obtusum, with main emphasis on the structural organization of the mitochondria and the leucoplast. Both organelles have been demonstrated to contain DNA aggregates as well as ribosomal particles within their matrix material. Reconstructions from serial showed that (a) the mitochondria were highly convoluted and irregular in shape and size, and (b) the leucoplast was a single cup- shaped entity, with large starch grains, localized at the posterior end, and multiple sites of DNA aggregates. The starch-containing compartments appeared to be interconnected by narrow tubular or sheetlike bridges. Cytoplasmic invaginations into the plastid, often containing mitochondria, were of frequent occurrence, and membranes of mitochondria and the leucoplast appeared to be closely apposed. Membranes elements, both sheetlike and vesicular, were also present in the matrix. The Polytoma leucoplast was, in certain respects, morphologically similar to the plastids of various photosynthetic mutants of Chlamydomonas, most of which show Menedelian segregation. It is suggested that Polytoma arose from a Chlamydomonas-like ancestor, possibly through combined mutational processess of both chloroplast and nuclear genomes. Since Polytoma leucoplasts contain both DNA and ribosomal particles, it is probable that these organelles still possess semiautonomy and limited ability for protein synthesis. The Rockefeller University Press 1976-05-01 /pmc/articles/PMC2109689/ /pubmed/177431 Text en This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/4.0/).
spellingShingle Articles
Characterization of cytoplasmic and nuclear genomes in the colorless alga Polytoma. I. Ultrastructural analysis of organelles
title Characterization of cytoplasmic and nuclear genomes in the colorless alga Polytoma. I. Ultrastructural analysis of organelles
title_full Characterization of cytoplasmic and nuclear genomes in the colorless alga Polytoma. I. Ultrastructural analysis of organelles
title_fullStr Characterization of cytoplasmic and nuclear genomes in the colorless alga Polytoma. I. Ultrastructural analysis of organelles
title_full_unstemmed Characterization of cytoplasmic and nuclear genomes in the colorless alga Polytoma. I. Ultrastructural analysis of organelles
title_short Characterization of cytoplasmic and nuclear genomes in the colorless alga Polytoma. I. Ultrastructural analysis of organelles
title_sort characterization of cytoplasmic and nuclear genomes in the colorless alga polytoma. i. ultrastructural analysis of organelles
topic Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2109689/
https://www.ncbi.nlm.nih.gov/pubmed/177431