Radial spoke protein 9 is necessary for axoneme assembly in <i>Plasmodium</i> but not in trypanosomatid parasites

Flagella are important for eukaryote cell motility, including in sperm, and are vital for life cycle progression of many unicellular eukaryotic pathogens. The ‘9+2’ axoneme in most motile flagella comprises nine outer doublet and two central-pair singlet microtubules. T-shaped radial spokes protrude from the outer doublets towards the central pair and are necessary for effective beating. We asked whether there were radial spoke adaptations associated with parasite lineage-specific properties in apicomplexans and trypanosomatids. Following an orthologue search for experimentally uncharacterised radial spoke proteins (RSPs), we identified and analysed RSP9. Trypanosoma brucei and Leishmania mexicana have an extensive RSP complement, including two divergent RSP9 orthologues, necessary for flagellar beating and swimming. Detailed structural analysis showed that neither orthologue is needed for axoneme assembly in Leishmania. In contrast, Plasmodium has a reduced set of RSPs including a single RSP9 orthologue, deletion of which in Plasmodium berghei leads to failure of axoneme formation, failed male gamete release, greatly reduced fertilisation and inefficient life cycle progression in the mosquito. This indicates contrasting selection pressures on axoneme complexity, likely linked to the different mode of assembly of trypanosomatid versus Plasmodium flagella

Deux tombes féminines, atypiques et privilégiées, de la nécropole du Bas-Empire d’Arcis-sur-Aube (Champagne-Ardenne)

En 2002, une nécropole a été partiellement fouillée au sud de la commune d’Arcis-sur-Aube (Aube, Champagne-Ardenne). Cette opération a permis d’exhumer vingt-deux tombes datées entre la fin du IIIe et le milieu du IVe siècle. Malgré des pratiques de dépôt partagées par la plupart des défunts, deux tombes se distinguent. Ces deux fosses, aménagées avec un double coffrage, accueillent deux défuntes qui possèdent des dépôts très similaires. La qualité des dépôts, leur disposition dans la fosse, ainsi que la proximité des creusements, signalent une volonté du groupe de mettre en exergue ces deux femmes. De plus, une particularité dentaire encourage à voir entre elles un possible apparentement.In 2002, a necropolis to the south of the commune of Arcis-sur-Aube (Aube, Champagne-Ardenne) was excavated. Twenty-two tombs were exhumed and dated to between the end of the 3rd and middle of the 4th century. While most of the deceased were deposited in the same manner, two tombs differ from the others. These two pits, constructed a double coffering, contained two individuals with very similar grave goods. The quality of these objects, their arrangement in the pits, and the proximity of the pits to each other indicate that the group intended to highlight these two women. Moreover, a shared dental feature could indicate a kinship relationship between them.2002 wurden im Süden der Gemeinde Arcis-sur-Aube (Departement Aube, Champagne-Ardenne) bei der teilweisen Ausgrabung einer Nekropole 22 Bestattungen freigelegt, die zwischen das Ende des 3. und die Mitte des 4. Jh. datierten. Die Beigaben sind in den meisten Gräbern identisch. Nur zwei doppelt verschalte Gräber weisen Unterschiede auf. Hier ruhten zwei weibliche Verstorbene mit sehr ähnlichen Grabbeigaben. Deren Qualität, Anordnung in der Grube sowie die Nähe der beiden Grabstätten zu einander zeugen von dem Sonderstatus der beiden Frauen innerhalb der Gruppe. Eine Eigentümlichkeit der Zähne legt eine verwandtschaftliche Beziehung zwischen den Frauen nah

Bidirectional intraflagellar transport is restricted to two sets of microtubule doublets in the trypanosome flagellum

Intraflagellar transport (IFT) is the rapid bidirectional movement of large protein complexes driven by kinesin and dynein motors along microtubule doublets of cilia and flagella. In this study, we used a combination of high-resolution electron and light microscopy to investigate how and where these IFT trains move within the flagellum of the protist Trypanosoma brucei. Focused ion beam scanning electron microscopy (FIB-SEM) analysis of trypanosomes showed that trains are found almost exclusively along two sets of doublets (3–4 and 7–8) and distribute in two categories according to their length. High-resolution live imaging of cells expressing mNeonGreen::IFT81 or GFP::IFT52 revealed for the first time IFT trafficking on two parallel lines within the flagellum. Anterograde and retrograde IFT occurs on each of these lines. At the distal end, a large individual anterograde IFT train is converted in several smaller retrograde trains in the space of 3–4 s while remaining on the same side of the axoneme

Effects of Genotypes and Treatment on Oxygenscan Parameters in Sickle Cell Disease

(1) Background: The aim of the present study was to compare oxygen gradient ektacytometry parameters between sickle cell patients of different genotypes (SS, SC, and S/β+) or under different treatments (hydroxyurea or chronic red blood cell exchange). (2) Methods: Oxygen gradient ektacytometry was performed in 167 adults and children at steady state. In addition, five SS patients had oxygenscan measurements at steady state and during an acute complication requiring hospitalization. (3) Results: Red blood cell (RBC) deformability upon deoxygenation (EImin) and in normoxia (EImax) was increased, and the susceptibility of RBC to sickle upon deoxygenation was decreased in SC patients when compared to untreated SS patients older than 5 years old. SS patients under chronic red blood cell exchange had higher EImin and EImax and lower susceptibility of RBC to sickle upon deoxygenation compared to untreated SS patients, SS patients younger than 5 years old, and hydroxyurea-treated SS and SC patients. The susceptibility of RBC to sickle upon deoxygenation was increased in the five SS patients during acute complication compared to steady state, although the difference between steady state and acute complication was variable from one patient to another. (4) Conclusions: The present study demonstrates that oxygen gradient ektacytometry parameters are affected by sickle cell disease (SCD) genotype and treatment

Elongation of the axoneme and dynamics of intraflagellar transport

International audienceCilia and flagella are essential organelles in most eukaryotes including human beings. In this review, we will discuss the mode of assembly of these complex organelles that depends on a dynamic process called intraflagellar transport or IFT. IFT delivers structural elements at the distal end of the cilium where assembly takes place, thereby allowing the growth of the organelle. We next discuss the different models for control of cilium length and their alterations in ciliopathies, genetic diseases associated to ciliary defects.Les cils et flagelles sont des organites essentiels chez la plupart des eucaryotes, y compris chez l’humain. Dans cette revue, nous abordons le mode d’assemblage de ces organites complexes, qui fait intervenir un processus dynamique dénommé transport intraflagellaire. Le transport intraflagellaire apporte les éléments structuraux au bout distal du cil où a lieu l’assemblage, permettant ainsi la croissance de l’organite. Nous exposons ensuite trois modèles différents de contrôle de la longueur du cil avant de discuter de leur altération lors des ciliopathies, maladies génétiques associées aux défauts ciliaires

Host species dominates over landscape structure in shaping foliar fungal communities

Host species dominates over landscape structure in shaping foliar fungal communities. 10. International symposium on phyllosphere microbiolog

Host species dominates over landscape structure in shaping foliar fungal communities

Host species dominates over landscape structure in shaping foliar fungal communities. 10. International symposium on phyllosphere microbiolog

Ces objets venus d'ailleurs... Images des échanges dans les tombes champenoises de La Tène ancienne au Bas-Empire

International audienceThe recurring presence of original objects in graves from all periods is a fact and evidence that some have been imported can be determined by archaeologists from the decoration on these objects, and by how and from what they were made. In funerary contexts, these objects can distinguish certain burial rites from others as they are markers of exchanges between different communities often established and controlled by the elite. In this paper, we will present some examples illustrating this link between power and the exchange of these objects