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Ribosomal DNA Organization Patterns within the Dinoflagellate Genus Alexandrium as Revealed by FISH: Life Cycle and Evolutionary Implications.

Figueroa, Rosa LU ; Cuadrado, Angeles; Stüken, Anke; Rodríguez, Francisco and Fraga, Santiago (2014) In Protist 165(3). p.343-363
Abstract
Dinoflagellates are a group of protists whose genome differs from that of other eukaryotes in terms of size (contains up to 250pg per haploid cell), base composition, chromosomal organization, and gene expression. But rDNA gene mapping of the active nucleolus in this unusual eukaryotic genome has not been carried out thus far. Here we used FISH in dinoflagellate species belonging to the genus Alexandrium (genome sizes ranging from 21 to 170 pg of DNA per haploid genome) to localize the sequences encoding the 18S, 5.8S, and 28S rRNA genes. The results can be summarized as follows: 1) Each dinoflagellate cell contains only one active nucleolus, with no hybridization signals outside it. However, the rDNA organization varies among species,... (More)
Dinoflagellates are a group of protists whose genome differs from that of other eukaryotes in terms of size (contains up to 250pg per haploid cell), base composition, chromosomal organization, and gene expression. But rDNA gene mapping of the active nucleolus in this unusual eukaryotic genome has not been carried out thus far. Here we used FISH in dinoflagellate species belonging to the genus Alexandrium (genome sizes ranging from 21 to 170 pg of DNA per haploid genome) to localize the sequences encoding the 18S, 5.8S, and 28S rRNA genes. The results can be summarized as follows: 1) Each dinoflagellate cell contains only one active nucleolus, with no hybridization signals outside it. However, the rDNA organization varies among species, from repetitive clusters forming discrete nuclear organizer regions (NORs) in some to specialized "ribosomal chromosomes" in other species. The latter chromosomes, never reported before in other eukaryotes, are mainly formed by rDNA genes and appeared in the species with the highest DNA content. 2) Dinoflagellate chromosomes are first characterized by several eukaryotic features, such as structural differentiation (centromere-like constrictions), size differences (dot chromosomes), and SAT (satellite) chromosomes. 3) NOR patterns prove to be useful in discriminating between cryptic species and life cycle stages in protists. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Protist
volume
165
issue
3
pages
343 - 363
publisher
Elsevier
external identifiers
  • pmid:24846057
  • wos:000338826400008
  • scopus:84901049579
ISSN
1434-4610
DOI
10.1016/j.protis.2014.04.001
language
English
LU publication?
yes
id
874c444b-6318-4fe0-90ab-f14b890f40bb (old id 4454015)
date added to LUP
2014-06-09 13:14:32
date last changed
2017-11-05 03:24:34
@article{874c444b-6318-4fe0-90ab-f14b890f40bb,
  abstract     = {Dinoflagellates are a group of protists whose genome differs from that of other eukaryotes in terms of size (contains up to 250pg per haploid cell), base composition, chromosomal organization, and gene expression. But rDNA gene mapping of the active nucleolus in this unusual eukaryotic genome has not been carried out thus far. Here we used FISH in dinoflagellate species belonging to the genus Alexandrium (genome sizes ranging from 21 to 170 pg of DNA per haploid genome) to localize the sequences encoding the 18S, 5.8S, and 28S rRNA genes. The results can be summarized as follows: 1) Each dinoflagellate cell contains only one active nucleolus, with no hybridization signals outside it. However, the rDNA organization varies among species, from repetitive clusters forming discrete nuclear organizer regions (NORs) in some to specialized "ribosomal chromosomes" in other species. The latter chromosomes, never reported before in other eukaryotes, are mainly formed by rDNA genes and appeared in the species with the highest DNA content. 2) Dinoflagellate chromosomes are first characterized by several eukaryotic features, such as structural differentiation (centromere-like constrictions), size differences (dot chromosomes), and SAT (satellite) chromosomes. 3) NOR patterns prove to be useful in discriminating between cryptic species and life cycle stages in protists.},
  author       = {Figueroa, Rosa and Cuadrado, Angeles and Stüken, Anke and Rodríguez, Francisco and Fraga, Santiago},
  issn         = {1434-4610},
  language     = {eng},
  number       = {3},
  pages        = {343--363},
  publisher    = {Elsevier},
  series       = {Protist},
  title        = {Ribosomal DNA Organization Patterns within the Dinoflagellate Genus Alexandrium as Revealed by FISH: Life Cycle and Evolutionary Implications.},
  url          = {http://dx.doi.org/10.1016/j.protis.2014.04.001},
  volume       = {165},
  year         = {2014},
}