Axonemal Microtubule Pattern of Cienkowskya Mereschkovskyi and a Revision of Heliozoan Taxonomy

Febvre-Chevalier, Colette; Febvre, Jean

doi:10.1007/978-94-009-6398-6_13

Cited by 5 publications

(10 citation statements)

References 24 publications

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“…Their numerous axopods are thin extensions into the environment that contain two interlocking spiral sheets of microtubules subdivided into 12 sectors ( Figure 6B ; Tilney and Byers, 1969 ). Some heliozoans have triangular or hexagonal microtubule arrangements in their axopods ( Febvre-Chevalier and Febvre, 1984 ). These axonemes emanate from a point known as the centroplast or from trilaminar plaques on the nuclear membrane ( Tilney, 1971 ; Cachon et al.…”

Section: Higher-order Microtubule Assembliesmentioning

confidence: 99%

A microtubule bestiary: structural diversity in tubulin polymers

Chaaban

Brouhard

2017

MBoC

141

112

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Microtubules are long, slender polymers of αβ-tubulin found in all eukaryotic cells. Tubulins associate longitudinally to form protofilaments, and adjacent protofilaments associate laterally to form the microtubule. In the textbook view, microtubules are 1) composed of 13 protofilaments, 2) arranged in a radial array by the centrosome, and 3) built into the 9+2 axoneme. Although these canonical structures predominate in eukaryotes, microtubules with divergent protofilament numbers and higher-order microtubule assemblies have been discovered throughout the last century. Here we survey these noncanonical structures, from the 4-protofilament microtubules of Prosthecobacter to the 40-protofilament accessory microtubules of mantidfly sperm. We review the variety of protofilament numbers observed in different species, in different cells within the same species, and in different stages within the same cell. We describe the determinants of protofilament number, namely nucleation factors, tubulin isoforms, and posttranslational modifications. Finally, we speculate on the functional significance of these diverse polymers. Equipped with novel tubulin-purification tools, the field is now prepared to tackle the long-standing question of the evolutionary basis of microtubule structure.

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Section: Higher-order Microtubule Assembliesmentioning

confidence: 99%

A microtubule bestiary: structural diversity in tubulin polymers

Chaaban

Brouhard

2017

MBoC

141

112

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“…Heliozoa are Actinopoda, ie protists having a radial symmetry resulting from the outsrowth of long thin extensions called axopods stiffened by a cytoskeletal axis which eonsists of patterned arrays of microtubules [17,23]. These axopodia arise from microtubule organizing centers (MTOCs) that are dispersed in the cytoplasm or on the nuclear envelope (order Cryptaxohelida, according to Febvre.Chevalier and Febvre [24]), or are clustered in a central dense body bearing strong similarities to a centrosome, (order Centrohelida). The ultrastructural organization of this MTOC is variable [2-4, 22-24, 45].…”

Section: Introductionmentioning

confidence: 99%

“…The ultrastructural organization of this MTOC is variable [2-4, 22-24, 45]. It is called an axoplast when it is made up simply of a central fibrous and microgranular sphere, and a centroplast when the central sphere is composed of a trilamellar disc sandwiched between two hemispherical caps of fibrillar material [24].…”

Section: Introductionmentioning

confidence: 99%

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Cell division in the heliozoan Dimorpha mutans and evolution of centrosomal organization during the cell cycle

Mignot

Brugerolle

1991

Biology of the Cell

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Summary— The heliozoan Dimorpha mutans possesses a complex centrosome, consisting of an axoplast which anchors radiating axopodia crossing the nucleus, two kinetosomes and different associated fibres, including striated roots. During mitosis, which is an open orthomitosis, the axoplast separates into two, then dissociates, and most of the axopodia disappear. The axoplast therefore does not transform directly into asters at the poles of the mitotic spindle, as previously suggested. The spindle poles are made up of diffuse material which appears to be linked with a pair of kinetosomes by a short striated fibre. No differentiated kinetochore was observed. At the end of telophase, some axopodial axonemes appear to be reconstituted by the juxtaposition of microtubules before the axoplast reappears. The channels followed by the axopodial axonemes crossing the nucleus were formed when the nuclear envelope reconstituted around the chromosomes. From these observations, and those on other protists, it is suggested that the centrosome results from the concentration during the cell cycle of a heterogenous group of microtubule organizing centers (MTOCs), of which the centriole might be only one of the types.

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“…CENTROHELID heliozoans (Centroplasthelida Febvre‐Chevalier et Febvre ) represent a ubiquitous group of unciliated free‐living predatory protists forming cysts (Cavalier‐Smith et al. ; Zlatogursky ).…”

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confidence: 99%

Multiple Euryhaline Lineages of Centrohelids (Haptista: Centroplasthelida) in Inland Saline Waters Revealed with Metabarcoding

Герасимова

Плотников

Khlopko

et al. 2019

J Eukaryotic Microbiology

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The diversity of centrohelids in inland saline waters was studied with metabarcoding for the first time. The fragment of V6–V7 regions of 18S rDNA was sequenced with newly designed primers. Obtained OTUs were identified with molecular phylogenetic analysis and comparison of the signatures in 39es9 hairpin of V7. The obtained data included some OTUs, which could be attributed to four described species, but the majority belonged to previously established or novel environmental clades. Along with some presumably marine/brackish clades and freshwater/low salinity (0–2 ppt) clades, seven presumable species demonstrating broad (from 1–2 up to 78 ppt) salinity tolerance were detected. A number of OTUs belonged to Raphidocystis contractilis, which is known from three independent findings in brackish habitats only. Thus, it was assumed that this species is stenohaline and specifically adapted to salinity 5–15 ppt. The high level of salinity tolerance was suggested for centrohelids before based on morphology, which was used to justify their cosmopolitan distribution. Later these views were criticized based on environmental sequencing, but the results of the current survey indicate, that at least some species are present at salinities from almost freshwater (1–2 ppt) to twice oceanic (78 ppt) and are presumably capable of overcoming oceanic salinity barriers for their distribution.

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Axonemal Microtubule Pattern of Cienkowskya Mereschkovskyi and a Revision of Heliozoan Taxonomy

Cited by 5 publications

References 24 publications

A microtubule bestiary: structural diversity in tubulin polymers

A microtubule bestiary: structural diversity in tubulin polymers

Cell division in the heliozoan Dimorpha mutans and evolution of centrosomal organization during the cell cycle

Multiple Euryhaline Lineages of Centrohelids (Haptista: Centroplasthelida) in Inland Saline Waters Revealed with Metabarcoding

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