TFK1, a basal body transition fibre protein that is essential for cytokinesis in Trypanosoma brucei

In Trypanosoma brucei, transition fibres (TFs) form a nine-bladed pattern-like structure connecting the base of the flagellum to the flagellar pocket membrane. Despite the characterization of two TF proteins, CEP164C and T. brucei (Tb)RP2, little is known about the organization of these fibres. Here, we report the identification and characterization of the first kinetoplastid-specific TF protein, named TFK1 (Tb927.6.1180). Bioinformatics and functional domain analysis identified three distinct domains in TFK1 – an N-terminal domain of an unpredicted function, a coiled-coil domain involved in TFK1–TFK1 interaction and a C-terminal intrinsically disordered region potentially involved in protein interaction. Cellular immunolocalization showed that TFK1 is a newly identified basal body maturation marker. Furthermore, using ultrastructure expansion and immuno-electron microscopies we localized CEP164C and TbRP2 at the TF, and TFK1 on the distal appendage matrix of the TF. Importantly, RNAi-mediated knockdown of TFK1 in bloodstream form cells induced misplacement of basal bodies, a defect in the furrow or fold generation, and eventually cell death. We hypothesize that TFK1 is a basal body positioning-specific actor and a key regulator of cytokinesis in the bloodstream form Trypanosoma brucei

Murine Models for Trypanosoma brucei gambiense Disease Progression—From Silent to Chronic Infections and Early Brain Tropism

Trypanosoma brucei gambiense is responsible for more than 90% of reported cases of human African trypanosomosis (HAT). Infection can last for months or even years without major signs or symptoms of infection, but if left untreated, sleeping sickness is always fatal. In the present study, different T. b. gambiense field isolates from the cerebrospinal fluid of patients with HAT were adapted to growth in vitro. These isolates belong to the homogeneous Group 1 of T. b. gambiense, which is known to induce a chronic infection in humans. In spite of this, these isolates induced infections ranging from chronic to silent in mice, with variations in parasitaemia, mouse lifespan, their ability to invade the CNS and to elicit specific immune responses. In addition, during infection, an unexpected early tropism for the brain as well as the spleen and lungs was observed using bioluminescence analysis. The murine models presented in this work provide new insights into our understanding of HAT and allow further studies of parasite tropism during infection, which will be very useful for the treatment and the diagnosis of the disease

A MAP6-Related Protein Is Present in Protozoa and Is Involved in Flagellum Motility

In vertebrates the microtubule-associated proteins MAP6 and MAP6d1 stabilize cold-resistant microtubules. Cilia and flagella have cold-stable microtubules but MAP6 proteins have not been identified in these organelles. Here, we describe TbSAXO as the first MAP6-related protein to be identified in a protozoan, Trypanosoma brucei. Using a heterologous expression system, we show that TbSAXO is a microtubule stabilizing protein. Furthermore we identify the domains of the protein responsible for microtubule binding and stabilizing and show that they share homologies with the microtubule-stabilizing Mn domains of the MAP6 proteins. We demonstrate, in the flagellated parasite, that TbSAXO is an axonemal protein that plays a role in flagellum motility. Lastly we provide evidence that TbSAXO belongs to a group of MAP6-related proteins (SAXO proteins) present only in ciliated or flagellated organisms ranging from protozoa to mammals. We discuss the potential roles of the SAXO proteins in cilia and flagella function

Nouveau polymères sorbant pour la récupération des lanthanides pour leurs mises en œuvre dans des procédés de séparation assisté par complexation sur polymères (PEUF/PAUF)

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Kinetics of Structural and Microstructural Changes at the Solid/Solution Interface during Dissolution of Cerium(IV)–Neodymium(III) Oxides

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The first report on phosphonate-based homopolymers combining both chelating and thermosensitive properties of gadolinium: synthesis and evaluation

International audienceAn original phosphonate-based acrylamide was first prepared in four steps including the incorporation of a valuable carbamoylmethylphosphonate moiety. This monomer was then polymerized, thus leading to poly(diethyl-6-(acrylamido)hexylcarbamoylmethylphosphonate) (P(CPAAm6C)), combining both thermosensitivity and chelating properties. The influence of different parameters (polymer concentration, salt, and acidity) on the P(CPAAm6C) cloud point was determined, mainly considering the salting-out and salting-in effect related to the Hofmeister series. Finally, it was proved that thermosensitive P(CPAAm6C) was efficient for the complexation of gadolinium below and above the cloud point. The latter logically depended on the Gd sorption. To our knowledge, the P(CPAAm6C) polymer represents the only example reported in the literature where only one monomeric unit can allow, on the one hand, the complexation of rare earth elements, in particular gadolinium, and, on the other hand, thermo-responsive properties. The poly(diethyl-6-(acrylamido)hexylcarbamoylmethylphosphonate) polymers open the way to new materials that could be used for the treatment of rare earth elements containing effluents, allowing their recovery while possibly recycling the homopolymer

Dilatometric study of U1−xAmxO2±δ and U1−xCexO2±δ reactive sintering

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Sorption properties of carbamoylmethylphosphonated-based polymer combining both sorption and thermosensitive properties: New valuable hydrosoluble materials for rare earth elements sorption

International audienceThe sorption properties of gadolinium (Gd) by an original carbamoylmethylphosphonate (cmp)-based acrylamide polymer combining both chelating and thermosensitive properties namely poly(diethyl-6-(acrylamido)hexylcarbamoyl-methylphosphonate) (P(CPAAm6C)) are presented for the first time. For pH = 1 and at 20 °C, the maximum sorption capacity reached 0.6 mmol·g−1 for the highest Gd concentrations. Different parameters influencing the sorption of Gd were studied as pH, ionic strenght and temperature. The temperature was shown to influence both the sorption and the stability of the complex cmp-Gd formed by coordination mode with CO and PO functions. The selectivity of the cmp group for Gd was demonstrated in Gd/Ni mixture and shows its thermosensitive polymer is very promising for the development of selective sorption processes