Structural changes of dinoflagellate chromosomes by pronase and ribonuclease

Soyer, Marie-Odile; Haapala, O. K.

doi:10.1007/bf00331805

Cited by 49 publications

(16 citation statements)

References 16 publications

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“…Their mitosis, named dinomitosis by Chatton [4], differs considerably from the higher eukaryote mitosis; in particular, the nuclear envelope is present throughout the cell cycle, even during mito. sis; the mitotic microtubular spindle is totally extranuclear [17,24,34], and the segregation of the chromosomes is effected in direct contact with the nuclear envelope [17,37]. One of the most intersting characteristics concerns their chromosomes, which are permanently condensed throughout the cell cycle, with a twisted helicoidal organization of their nucleofilaments [13].…”

Section: Introductionmentioning

confidence: 99%

Immunocytochemical localization of the DNA‐binding protein HCc during the cell cycle of the histone‐less dinoflagellate protoctista Crypthecodinium cohnii B

Géraud

Sala-Rovira

Herzog

et al. 1991

Biology of the Cell

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Summary— The major basic nuclear protein HCc (previously named Histone‐like) of the dinoflagellate Crypthecodinium cohnii B was immunolocalized in light and electron microscopy using an affinity‐purified polyclonal antibody. Complementary conventional and cryo‐techniques were used to study the distribution of the DNA‐binding protein in interphase cells and to follow its behaviour throughout the mitotic cycle. In non‐dividing cells, the HCc protein was found to be located on extra‐chromosomal loops and chromosomal nucleofilaments dispersed in the nucleoplasm. In mitotic cells, from prophase to early telophase, it was homogeneously distributed in the (whole) dividing chromosomes. HCc protein was also detected in two compartments of all the permanently observable nucleoli: the nucleolar organizing region and the fibrillo‐granular region. In this paper we discuss the hypothetical roles, structural and/or functional, of this DNA‐binding protein, which is specific to dinoflagellates, the only eukaryotes whose chromatin is devoid of histones and nucleosomes.

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Section: Introductionmentioning

confidence: 99%

Immunocytochemical localization of the DNA‐binding protein HCc during the cell cycle of the histone‐less dinoflagellate protoctista Crypthecodinium cohnii B

Géraud

Sala-Rovira

Herzog

et al. 1991

Biology of the Cell

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“…The nucleus contains many chromosomes in permanent condensed state (Figs 6-8), as typical for dinophyceans (Dodge & Greuet, 1986 ;Soyer & Haapala, 1974), and a prominent nucleolus, having a homogeneous density. Occasional masses of a non-identified dense material, similar to that of the nucleolus, were noted nearby, partially enclosed by a double membrane (Fig .…”

Section: Resultsmentioning

confidence: 95%

Symbiosis between a pelagic flatworm and a dinoflagellate from a tropical area: structural observations

Lopes

Silveira

1994

Hydrobiologia

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A morphological account on the endosymbiosis between Amphiscolops sp and Amphidinium sp is given, based on scanning and transmission electron microscopy observations . The algal symbionts (15-20 ,um in diameter) are found among cells of the peripheral parenchyma . Amphidinium sp . has a single pyrenoid of the multiple-stalked type, with several chloroplast lobes radiating from it . A comparison with A . klebsii is made. Our observations reinforce the assumption of selectivity of Amphiscolops for the symbiotic genus Amphidinium .

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“…Little is known about their organization of permanently condensed chromatin (43) or the associated histone-like proteins (5,44). Histones are the molecular solution to chromosomal DNA compaction in eukaryotes, and probably enabled the divergence of the eukaryotes from the prokaryotes.…”

Section: Discussionmentioning

confidence: 99%

Concentration-dependent organization of DNA by the dinoflagellate histone-like protein HCc3

Chan¹,

Wong²

2007

Nucleic Acids Research

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The liquid crystalline chromosomes of dinoflagellates are the alternative to the nucleosome-based organization of chromosomes in the eukaryotes. These nucleosome-less chromosomes have to devise novel ways to maintain active parts of the genome. The dinoflagellate histone-like protein HCc3 has significant sequence identity with the bacterial DNA-binding protein HU. HCc3 also has a secondary structure resembling HU in silico. We have examined HCc3 in its recombinant form. Experiments on DNA-cellulose revealed its DNA-binding activity is on the C-terminal domain. The N-terminal domain is responsible for intermolecular oligomerization as demonstrated by cross-linking studies. However, HCc3 could not complement Escherichia coli HU-deficient mutants, suggesting functional differences. In ligation assays, HCc3-induced DNA concatenation but not ring closure as the DNA-bending HU does. The basic HCc3 was an efficient DNA condensing agent, but it did not behave like an ordinary polycationic compound. HCc3 also induced specific structures with DNA in a concentration-dependent manner, as demonstrated by atomic force microscopy (AFM). At moderate concentration of HCc3, DNA bridging and bundling were observed; at high concentrations, the complexes were even more condensed. These results are consistent with a biophysical role for HCc3 in maintaining extended DNA loops at the periphery of liquid crystalline chromosomes.

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Structural changes of dinoflagellate chromosomes by pronase and ribonuclease

Cited by 49 publications

References 16 publications

Immunocytochemical localization of the DNA‐binding protein HCc during the cell cycle of the histone‐less dinoflagellate protoctista Crypthecodinium cohnii B

Immunocytochemical localization of the DNA‐binding protein HCc during the cell cycle of the histone‐less dinoflagellate protoctista Crypthecodinium cohnii B

Symbiosis between a pelagic flatworm and a dinoflagellate from a tropical area: structural observations

Concentration-dependent organization of DNA by the dinoflagellate histone-like protein HCc3

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