Tag: dinoflagellates

Jan 21

Loss of nucleosomal DNA condensation coincides with appearance of a novel nuclear protein in dinoflagellates.

Related Articles

Loss of nucleosomal DNA condensation coincides with appearance of a novel nuclear protein in dinoflagellates.

Curr Biol. 2012 Dec 18;22(24):2303-12

Authors: Gornik SG, Ford KL, Mulhern TD, Bacic A, McFadden GI, Waller RF

Abstract
BACKGROUND: The packaging, expression, and maintenance of nuclear genomes using histone proteins is a ubiquitous and fundamental feature of eukaryotic cells, yet the phylum Dinoflagellata has apparently abandoned this model of nuclear organization. Their nuclei contain permanently condensed, liquid crystalline chromosomes that seemingly lack histone proteins, and contain remarkably large genomes. The molecular basis for this reorganization is poorly understood, as is the sequence of evolutionary events that led to such radical change. We have investigated nuclear organization in the closest relative to dinoflagellates, Perkinsus marinus, and an early-branching dinoflagellate, Hematodinium sp., to identify early changes that occurred during dinoflagellate nuclear evolution.
RESULTS: We show that P. marinus has a typical nuclear organization that is based on the four core histones. By the early divergence of Hematodinium sp., however, dinoflagellate genome size is dramatically enlarged, chromosomes are permanently condensed, and histones are scarcely detectable. In place of histones, we identify a novel, dominant family of nuclear proteins that is only found in dinoflagellates and, surprisingly, in a family of large algal viruses, the Phycodnaviridae. These new proteins, which we call DVNPs (dinoflagellate/viral nucleoproteins), are highly basic, bind DNA with similar affinity to histones, and occur in multiple posttranslationally modified forms. We find these proteins throughout all dinoflagellates, including early- and late-branching taxa, but not in P. marinus.
CONCLUSIONS: Gain of a major novel family of nucleoproteins, apparently from an algal virus, occurred early in dinoflagellate evolution and coincides with rapid and dramatic reorganization of the dinoflagellate nucleus.

PMID: 23159597 [PubMed – in process]

Jan 21

Molecular detection and species identification of Alexandrium (Dinophyceae) causing harmful algal blooms along the Chilean coastline.

Related Articles

Molecular detection and species identification of Alexandrium (Dinophyceae) causing harmful algal blooms along the Chilean coastline.

AoB Plants. 2012;2012:pls033

Authors: Jedlicki A, Fernández G, Astorga M, Oyarzún P, Toro JE, Navarro JM, Martínez V

Abstract
BACKGROUND AND AIMS: On the basis of morphological evidence, the species involved in South American Pacific coast harmful algal blooms (HABs) has been traditionally recognized as Alexandrium catenella (Dinophyceae). However, these observations have not been confirmed using evidence based on genomic sequence variability. Our principal objective was to accurately determine the species of Alexandrium involved in local HABs in order to implement a real-time polymerase chain reaction (PCR) assay for its rapid and easy detection on filter-feeding shellfish, such as mussels.
METHODOLOGY: For species-specific determination, the intergenic spacer 1 (ITS1), 5.8S subunit, ITS2 and the hypervariable genomic regions D1-D5 of the large ribosomal subunit of local strains were sequenced and compared with two data sets of other Alexandrium sequences. Species-specific primers were used to amplify signature sequences within the genomic DNA of the studied species by conventional and real-time PCR.
PRINCIPAL RESULTS: Phylogenetic analysis determined that the Chilean strain falls into Group I of the tamarensis complex. Our results support the allocation of the Chilean Alexandrium species as a toxic Alexandrium tamarense rather than A. catenella, as currently defined. Once local species were determined to belong to Group I of the tamarensis complex, a highly sensitive and accurate real-time PCR procedure was developed to detect dinoflagellate presence in Mytilus spp. (Bivalvia) samples after being fed (challenged) in vitro with the Chilean Alexandrium strain. The results show that real-time PCR is useful to detect Alexandrium intake in filter-feeding molluscs.
CONCLUSIONS: It has been shown that the classification of local Alexandrium using morphological evidence is not very accurate. Molecular methods enabled the HAB dinoflagellate species of the Chilean coast to be assigned as A. tamarense rather than A. catenella. Real-time PCR analysis based on A. tamarense primers allowed the detection of dinoflagellate DNA in Mytilus spp. samples exposed to this alga. Through the specific assignment of dinoflagellate species involved in HABs, more reliable preventive policies can be implemented.

PMID: 23259043 [PubMed]

Dec 30

Chloroplast genomes of photosynthetic eukaryotes.

Chloroplast genomes of photosynthetic eukaryotes.
Plant J. 2011 Apr;66(1):34-44
Authors: Green BR
Abstract
Chloroplast genomes have retained a core set of genes from their cyanobacterial ancestor, most of the…

Dec 30

Rampant gene loss in the underground orchid Rhizanthella gardneri highlights evolutionary constraints on plastid genomes.

Rampant gene loss in the underground orchid Rhizanthella gardneri highlights evolutionary constraints on plastid genomes.
Mol Biol Evol. 2011 Jul;28(7):2077-86
Authors: Delannoy E, Fujii S, Colas des Francs-Small C, Brundre…

Dec 30

Alveolate phylogeny inferred using concatenated ribosomal proteins.

Alveolate phylogeny inferred using concatenated ribosomal proteins.
J Eukaryot Microbiol. 2011 May-Jun;58(3):223-33
Authors: Bachvaroff TR, Handy SM, Place AR, Delwiche CF
Abstract
Dinoflagellates and apicomp…

Dec 30

Genomic understanding of dinoflagellates.

Genomic understanding of dinoflagellates.
Res Microbiol. 2011 Jul-Aug;162(6):551-69
Authors: Lin S
Abstract
The phylum of dinoflagellates is characterized by many unusual and interesting genomic and physiolog…

Dec 30

Genomic and proteomic analyses of the coral pathogen Vibrio coralliilyticus reveal a diverse virulence repertoire.

Genomic and proteomic analyses of the coral pathogen Vibrio coralliilyticus reveal a diverse virulence repertoire.
ISME J. 2011 Sep;5(9):1471-83
Authors: Santos Ede O, Alves N, Dias GM, Mazotto AM, Vermelho A, Vora GJ, Wilso…

Dec 30

Discovery of nuclear-encoded genes for the neurotoxin saxitoxin in dinoflagellates.

Discovery of nuclear-encoded genes for the neurotoxin saxitoxin in dinoflagellates.
PLoS One. 2011;6(5):e20096
Authors: Stüken A, Orr RJ, Kellmann R, Murray SA, Neilan BA, Jakobsen KS
Abstract
Saxitoxin is …

Dec 30

Do red and green make brown?: perspectives on plastid acquisitions within chromalveolates.

Do red and green make brown?: perspectives on plastid acquisitions within chromalveolates.
Eukaryot Cell. 2011 Jul;10(7):856-68
Authors: Dorrell RG, Smith AG
Abstract
The chromalveolate “supergroup” is of key…

Dec 30

Genome evolution of a tertiary dinoflagellate plastid.

Genome evolution of a tertiary dinoflagellate plastid.
PLoS One. 2011;6(4):e19132
Authors: Gabrielsen TM, Minge MA, Espelund M, Tooming-Klunderud A, Patil V, Nederbragt AJ, Otis C, Turmel M, Shalchian-Tabrizi K, Lemieux C, …