Search results for "Flagellum"

The Chlamydomonas genome reveals the evolution of key animal and plant functions

2007

Chlamydomonas reinhardtii is a unicellular green alga whose lineage diverged from land plants over 1 billion years ago. It is a model system for studying chloroplast-based photosynthesis, as well as the structure, assembly, and function of eukaryotic flagella (cilia), which were inherited from the common ancestor of plants and animals, but lost in land plants. We sequenced the ∼120-megabase nuclear genome of Chlamydomonas and performed comparative phylogenomic analyses, identifying genes encoding uncharacterized proteins that are likely associated with the function and biogenesis of chloroplasts or eukaryotic flagella. Analyses of the Chlamydomonas genome advance our understanding of the a…

2017

AbstractBy moving essential body fluids and molecules, motile cilia and flagella govern respiratory mucociliary clearance, laterality determination and the transport of gametes and cerebrospinal fluid. Primary ciliary dyskinesia (PCD) is an autosomal recessive disorder frequently caused by non-assembly of dynein arm motors into cilia and flagella axonemes. Before their import into cilia and flagella, multi-subunit axonemal dynein arms are thought to be stabilized and pre-assembled in the cytoplasm through a DNAAF2–DNAAF4–HSP90 complex akin to the HSP90 co-chaperone R2TP complex. Here, we demonstrate that large genomic deletions as well as point mutations involving PIH1D3 are responsible for…

Silicateins, silicatein interactors and cellular interplay in sponge skeletogenesis: formation of glass fiber-like spicules

2012

Biomineralization processes are characterized by controlled deposition of inorganic polymers/minerals mediated by functional groups linked to organic templates. One metazoan taxon, the siliceous sponges, has utilized these principles and even gained the ability to form these polymers/minerals by an enzymatic mechanism using silicateins. Silicateins are the dominant protein species present in the axial canal of the skeletal elements of the siliceous sponges, the spicules, where they form the axial filament. Silicateins also represent a major part of the organic components of the silica lamellae, which are cylindrically arranged around the axial canal. With the demosponge Suberites domuncula …

Septins 2, 7 and 9 and MAP4 colocalize along the axoneme in the primary cilium and control ciliary length

2013

International audience; Septins are a large, evolutionarily conserved family of GTPases that form hetero-oligomers and interact with the actin-based cytoskeleton and microtubules. They are involved in scaffolding functions, and form diffusion barriers in budding yeast, the sperm flagellum and the base of primary cilia of kidney epithelial cells. We investigated the role of septins in the primary cilium of retinal pigmented epithelial (RPE) cells, and found that SEPT2 forms a 1:1:1 complex with SEPT7 and SEPT9 and that the three members of this complex colocalize along the length of the axoneme. Similar to observations in kidney epithelial cells, depletion of cilium-localized septins by siRN…

Movement dependent position changes of the antennular flagellum ofPalaemon xiphias (Risso)

1977

The angular positions of the outer flagellum ofPalaemon xiphias were obtained by cinematographic measurements during different phases of locomotion. Contrary to the upright resting position the flagella are stretched forward into a distinct starting position preliminary to any forward movement, and then pushed down with acceleration of swimming speed. These phenomena are discussed in context with comparable behaviour in other decapods and in insects.

Terricaulis silvestris gen. nov., sp. nov., a novel prosthecate, budding member of the family Caulobacteraceae isolated from forest soil

2020

The family Caulobacteraceae comprises prosthecate bacteria with a dimorphic cell cycle and also non-prosthecate bacteria. Cells of all described species divide by binary fission. Strain 0127_4T was isolated from forest soil in Baden Württemberg (Germany) and determined to be the first representative of the family Caulobacteraceae which divided by budding. Cells of strain 0127_4T were Gram-negative, rod-shaped, prosthecate, motile by means of a polar flagellum, non-spore-forming and non-capsulated. The strain formed small white colonies and grew aerobically and chemo-organotrophically utilizing organic acids, amino acids and proteinaceous substrates. 16S rRNA gene sequence analysis indicated…

Analysis of the axial filament in spicules of the demosponge Geodia cydonium: different silicatein composition in microscleres (asters) and megascler…

2007

The skeleton of the siliceous sponges (Porifera: Hexactinellida and Demospongiae) is supported by spicules composed of bio-silica. In the axial canals of megascleres, harboring the axial filaments, three isoforms of the enzyme silicatein (-alpha, -beta and -gamma) have been identified until now, using the demosponges Tethya aurantium and Suberites domuncula. Here we describe the composition of the proteinaceous components of the axial filament from small spicules, the microscleres, in the demosponge Geodia cydonium that possesses megascleres and microscleres. The morphology of the different spicule types is described. Also in G. cydonium the synthesis of the spicules starts intracellularly …

Pachyjoenia howa, a new symbiotic parabasalid joeniid flagellate of the termite Postelectrotermes howa

2005

The Joenia-like lophomonad of Postelectrotermes howa is identified by light and electron microscopy as a new genus and species Pachyjoenia howa. Its flagellar area of about 1800 flagella is dome shaped. Basal bodies bear a composite root oriented counterclockwise in addition to the clockwise hook-shaped lamina present in other joeniids. There are four parallel privileged basal bodies. The main parabasal fibre is twisted around the axostyle and splits into several branches bearing Golgi bodies. The axostyle trunk is conspicuous and composed of a bundle of ∼90 small axostyles. There are sausage-shaped bacterial endosymbionts mixed with hydrogenosomes in the cytoplasm and coccoid bacterial end…

Histochemical and electron microscopic analysis of spiculogenesis in the demosponge Suberites domuncula.

2006

The skeleton of demosponges is built of spicules consisting of biosilica. Using the primmorph system from Suberites domuncula, we demonstrate that silicatein, the biosilica-synthesizing enzyme, and silicase, the catabolic enzyme, are colocalized at the surface of growing spicules as well as in the axial filament located in the axial canal. It is assumed that these two enzymes are responsible for the deposition of biosilica. In search of additional potential structural molecules that might guide the mineralization process during spiculogenesis to species-specific spicules, electron microscopic studies with antibodies against galectin and silicatein were performed. These studies showed that …

Expression and compartmentalisation of the glycolytic enzymes GAPDH and pyruvate kinase in boar spermatogenesis

2008

Boar spermatozoa contain isoforms of both glyceraldehyde 3-phosphate dehydrogenase (GAPDH, EC 1.2.1.12) and pyruvate kinase (PK, EC 2.7.1.40). The sperm-specific forms, GAPDH-S and PK-S, are tightly bound to cell structures. By immunofluorescence microscopy GAPDH-S and PK-S were localised in the principal piece of the boar sperm flagellum as well as in the acrosomal region of the sperm head and at the head–midpiece junction. The midpiece of the flagellum, however, contains isoforms of GAPDH and PK that were only recognised by antibodies against somatic GAPDH and PK, respectively, but not by the antibodies against GAPDH-S and PK-S. In sections of boar testis, GAPDH-S and PK-S were first dete…