WDR90 is a centriolar microtubule wall protein important for centriole architecture integrity

Centrioles are characterized by a nine-fold arrangement of microtubule triplets held together by an inner protein scaffold. These structurally robust organelles experience strenuous cellular processes such as cell division or ciliary beating while performing their function. However, the molecular mechanisms underlying the stability of microtubule triplets, as well as centriole architectural integrity remain poorly understood. Here, using ultrastructure expansion microscopy for nanoscale protein mapping, we reveal that POC16 and its human homolog WDR90 are components of the microtubule wall along the central core region of the centriole. We further found that WDR90 is an evolutionary microtubule associated protein. Finally, we demonstrate that WDR90 depletion impairs the localization of inner scaffold components, leading to centriole structural abnormalities in human cells. Altogether, this work highlights that WDR90 is an evolutionary conserved molecular player participating in centriole architecture integrity.</jats:p

Molecular resolution imaging by post-labeling expansion single-molecule localization microscopy (Ex-SMLM)

Previous attempts to combine expansion microscopy (ExM) and single molecule localisation microscopy (SMLM) have proved challenging. Here the authors show that post-labelling Ex-SMLM improves labelling efficiency, reduces linkage error, and preserves ultrastructural details

New immigrant struggles in Italy's logistics industry

The wave of strikes in the logistics sector since 2008 is by far the most important struggle that has developed in Italy in the wake of the global economic crisis. In this article we reflect on its potential for the renewal of the labour movement. We ground our discussion in an analysis of global production transformations and migration as a factor of working class re-composition. We show that in Italy the crisis is determining an acute process of deindustrialisation, while austerity and harshening immigration restrictions are reinforcing the deregulation and racialisation of employment relation. Deindustrialisation, however, is matched by the growth of the logistics sector and its reorganisation along the lines of Just-in-Time production, which actually strengthens workers' bargaining power at the point of production. After describing working conditions in the sector, we present the main characteristics of logistics struggles. The mainly immigrant logistics workers have been able to exercise their power through blockades and strikes, obtaining improved agreements with some of the main logistics companies. In a context of increasingly generalised precarity, these struggles can inspire workers in other sectors and promote a process of international class re-composition

A helical inner scaffold provides a structural basis for centriole cohesion

International audienceThe ninefold radial arrangement of microtubule triplets (MTTs) is the hallmark of the centriole, a conserved organelle crucial for the formation of centrosomes and cilia. Although strong cohesion between MTTs is critical to resist forces applied by ciliary beating and the mitotic spindle, how the centriole maintains its structural integrity is not known. Using cryo-electron tomography and subtomogram averaging of centrioles from four evolutionarily distant species, we found that MTTs are bound together by a helical inner scaffold covering ~70% of the centriole length that maintains MTTs cohesion under compressive forces. Ultrastructure Expansion Microscopy (U-ExM) indicated that POC5, POC1B, FAM161A, and Centrin-2 localize to the scaffold structure along the inner wall of the centriole MTTs. Moreover, we established that these four proteins interact with each other to form a complex that binds microtubules. Together, our results provide a structural and molecular basis for centriole cohesion and geometry

A helical inner scaffold provides a structural basis for centriole cohesion

The ninefold radial arrangement of microtubule triplets (MTTs) is the hallmark of the centriole, a conserved organelle crucial for the formation of centrosomes and cilia. Although strong cohesion between MTTs is critical to resist forces applied by ciliary beating and the mitotic spindle, how the centriole maintains its structural integrity is not known. Using cryo–electron tomography and subtomogram averaging of centrioles from four evolutionarily distant species, we found that MTTs are bound together by a helical inner scaffold covering ~70% of the centriole length that maintains MTTs cohesion under compressive forces. Ultrastructure Expansion Microscopy (U-ExM) indicated that POC5, POC1B, FAM161A, and Centrin-2 localize to the scaffold structure along the inner wall of the centriole MTTs. Moreover, we established that these four proteins interact with each other to form a complex that binds microtubules. Together, our results provide a structural and molecular basis for centriole cohesion and geometry

Homogeneous multifocal excitation for high-throughput super-resolution imaging

Super-resolution microscopies have become an established tool in biological research. However, imaging throughput remains a main bottleneck in acquiring large datasets required for quantitative biology. Here we describe multifocal flat illumination for field-independent imaging (mfFIFI). By integrating mfFIFI into an instant structured illumination microscope (iSIM), we extend the field of view (FOV) to >100 x 100 mu m(2) while maintaining high-speed, multicolor, volumetric imaging at double the diffraction-limited resolution. We further extend the effective FOV by stitching adjacent images for fast live-cell super-resolution imaging of dozens of cells. Finally, we combine our flat-fielded iSIM with ultrastructure expansion microscopy to collect three-dimensional (3D) images of hundreds of centrioles in human cells, or thousands of purified Chlamydomonas reinhardtiic entrioles, per hour at an effective resolution of similar to 35 nm. Classification and particle averaging of these large datasets enables 3D mapping of posttranslational modifications of centriolar microtubules, revealing differences in their coverage and positioning