Type II topoisomerase activities in both the G1 and G2/M phases of the dinoflagellate cell cycle

Mak, Carmen K.M.; Hung, Vivian Wing‐Yin; Wong, Joseph T.Y.

doi:10.1007/s00412-006-0054-8

Cited by 4 publications

(5 citation statements)

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“…Topoisomerases have been detected in various dinoflagellates (Mínguez et al, 1994;Mak et al, 2005) and it was suggested that C. cohnii type II topoisomerase unwinds condensed chromosomes of the G1 phase of the cell cycle for transcription (Mak et al, 2006). Our results also raise the possibility that these topoisomerases may be important for exposing regions of the chromosomal DNA during replication and transcription in the Symbiodiniaceae.…”

Section: Massive Changes In Abundances Of Transcripts For Enzymes Invsupporting

confidence: 62%

Transcriptome Reprogramming of Symbiodiniaceae Breviolum minutum in Response to Casein Amino Acids Supplementation

et al. 2020

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Dinoflagellates in the family Symbiodiniaceae can live freely in ocean waters or form a symbiosis with a variety of cnidarians including corals, sea anemones, and jellyfish. Trophic plasticity of Symbiodiniaceae is critical to its ecological success as it moves between environments. However, the molecular mechanisms underlying these trophic shifts in Symbiodiniaceae are still largely unknown. Using Breviolum minutum strain SSB01 (designated SSB01) as a model, we showed that Symbiodiniaceae go through a physiological and transcriptome reprogramming when the alga is grown with the organic nitrogen containing nutrients in hydrolyzed casein, but not with inorganic nutrients. SSB01 grows at a much faster rate and maintains stable photosynthetic efficiency when supplemented with casein amino acids compared to only inorganic nutrients or seawater. These physiological changes are driven by massive transcriptome changes in SSB01 supplemented with casein amino acids. The levels of transcripts encoding proteins involved in altering DNA conformation such as DNA topoisomerases, histones, and chromosome structural components were all significantly changed. Functional enrichment analysis also revealed processes involved in translation, ion transport, generation of second messengers, and phosphorylation. The physiological and molecular changes that underlie in vitro trophic transitions in Symbiodiniaceae can serve as an orthogonal platform to further understand the factors that impact the Symbiodiniaceae lifestyle.

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Section: Massive Changes In Abundances Of Transcripts For Enzymes Invsupporting

confidence: 62%

Transcriptome Reprogramming of Symbiodiniaceae Breviolum minutum in Response to Casein Amino Acids Supplementation

et al. 2020

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“…These results correspond to some extent to our previous observations ( _ Zabka et al, 2014) showing that the prolonged treatment with other topoisomerase II inhibitors, ICRF-193 and doxorubicin, brings about almost complete decline in the G2-phase population and a significant accumulation of G1 cells. However, our present data clearly differ from those in animals, where ETO and EPC arrested cells in G2/M phase (Mak et al, 2005;Rello-Varona et al, 2006;Chiu et al, 2005;Litwiniec et al, 2013;Poljakov a et al, 2013). Thus, it cannot be excluded that the cell cycle checkpoints in plants are considerably less sensitive or much more refractory to DNA lesions and allow cells (after some adaptation time) to continue interphase and to enter mitotic division regardless of the persistence of DNA breaks or other types of topological abnormalities ( _ Zabka et al, 2012;Cools and De Veylder, 2009).…”

Section: Discussioncontrasting

confidence: 80%

“…Type II topoisomerase (Topo II) is involved in DNA replication, transcription, chromatin remodeling, condensation and chromosome segregation (Mak et al, 2005;Nitiss, 2009a). In an ATP-dependent reaction, by relaxation of positively and negatively supercoiled DNA, Topo II enables the removal of knots, supercoils and catenates (Champoux, 2001;Vos et al, 2011;Lane et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

The effects of anti-DNA topoisomerase II drugs, etoposide and ellipticine, are modified in root meristem cells of Allium cepa by MG132, an inhibitor of 26S proteasomes

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Winnicki

Polit

et al. 2015

Plant Physiology and Biochemistry

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“…The standard glutaraldehyde-osmium tetroxide protocol that was used previously for other dinoflagellate chromosomes (34) was employed for all cell fixation and TEM specimen preparation. Dinoflagellate cells for each species were harvested, fixed in 4% glutaraldehyde-0.1 M PIPES (1,4-piperazinediethanesulfonic) buffer overnight at 4°C, and then subjected to a secondary fixative of 1% osmium tetroxide-0.1 M PIPES buffer for 1 h at 4°C in the dark.…”

Section: Methodsmentioning

confidence: 99%

Birefringence and DNA Condensation of Liquid Crystalline Chromosomes

et al. 2010

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DNA can self-assemble in vitro into several liquid crystalline phases at high concentrations. The largest known genomes are encoded by the cholesteric liquid crystalline chromosomes (LCCs) of the dinoflagellates, a diverse group of protists related to the malarial parasites. Very little is known about how the liquid crystalline packaging strategy is employed to organize these genomes, the largest among living eukaryotes-up to 80 times the size of the human genome. Comparative measurements using a semiautomatic polarizing microscope demonstrated that there is a large variation in the birefringence, an optical property of anisotropic materials, of the chromosomes from different dinoflagellate species, despite their apparently similar ultrastructural patterns of bands and arches. There is a large variation in the chromosomal arrangements in the nuclei and individual karyotypes. Our data suggest that both macroscopic and ultrastructural arrangements affect the apparent birefringence of the liquid crystalline chromosomes. Positive correlations are demonstrated for the first time between the level of absolute retardance and both the DNA content and the observed helical pitch measured from transmission electron microscopy (TEM) photomicrographs. Experiments that induced disassembly of the chromosomes revealed multiple orders of organization in the dinoflagellate chromosomes. With the low protein-to-DNA ratio, we propose that a highly regulated use of entropy-driven force must be involved in the assembly of these LCCs. Knowledge of the mechanism of packaging and arranging these largest known DNAs into different shapes and different formats in the nuclei would be of great value in the use of DNA as nanostructural material.DNA molecules are the indispensable genetic material of every organism. Apart from having the encoding power of a 4-base double-stranded polymer, DNA also has an enormous capacity to be condensed. It is probably this ability that allowed the evolution of increasing genome sizes in the eukaryotes. Histone-mediated nucleosome-based chromatin is the prevailing method for DNA packaging, but it is not the only way that DNA is condensed in the eukaryotes. Highly compact liquid crystalline DNA has been reported in several animal sperm nuclei (11, 28) and was also found in the nucleosomeless liquid crystalline chromosomes (LCCs) of dinoflagellates. Neither animal sperm nuclei nor dinoflagellate nuclei employ histones. In fact, the histone core octamer may hinder the attainment of ultrahigh levels of condensation due to its restrictive volume. In the sperm model, protamine is a sperm-specific DNA-binding protein (ϳ7 kDa) that is an order of magnitude smaller than the histone core octamer, and it adopts a structural role in the organization of the male gametic genome (1, 3). It is this very reduction in the protein-to-DNA ratio that may well enable the high DNA compaction into a liquid crystalline state. The dinoflagellate chromosomes are known to have a proteinto-DNA ratio even smaller than those of the prokaryo...

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Type II topoisomerase activities in both the G1 and G2/M phases of the dinoflagellate cell cycle

Cited by 4 publications

References 0 publications

Transcriptome Reprogramming of Symbiodiniaceae Breviolum minutum in Response to Casein Amino Acids Supplementation

Transcriptome Reprogramming of Symbiodiniaceae Breviolum minutum in Response to Casein Amino Acids Supplementation

The effects of anti-DNA topoisomerase II drugs, etoposide and ellipticine, are modified in root meristem cells of Allium cepa by MG132, an inhibitor of 26S proteasomes

Birefringence and DNA Condensation of Liquid Crystalline Chromosomes

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