Search bioRxiv⌕ Search

Biology subjects

Theveny, L.

Publications and source records attributed to Theveny, L..

2 recordsLinked to original sources

CryoSamba: self-supervised deep volumetric denoising for cryo-electron tomography data

Cryogenic electron tomography (cryo-ET) has rapidly advanced as a high-resolution imaging tool for visualizing subcellular structures in 3D with molecular detail. Direct image inspection remains challenging due to inherent low signal-to-noise ratios (SNR). We introduce CryoSamba, a self-supervised deep learning-based model designed for denoising cryo-ET images. CryoSamba enhances single consecutive 2D planes in tomograms by averaging motion-compensated nearby planes through deep learning interpolation, effectively mimicking increased exposure. This approach amplifies coherent signals and reduces high-frequency noise, substantially improving tomogram contrast and SNR. CryoSamba operates on 3D volumes without needing pre-recorded images, synthetic data, labels or annotations, noise models, or paired volumes. CryoSamba suppresses high-frequency information less aggressively than do existing cryo-ET denoising methods, while retaining real information, as shown both by visual inspection and by Fourier shell correlation analysis of icosahedrally symmetric virus particles. Thus, CryoSamba enhances the analytical pipeline for direct 3D tomogram visual interpretation.

bioinformatics↗

An apical membrane complex controls rhoptry exocytosis and invasion in Toxoplasma

Apicomplexan parasites possess secretory organelles called rhoptries that undergo regulated exocytosis upon contact with the host. This process is essential for the parasitic lifestyle of these pathogens and relies on an exocytic machinery sharing structural features and molecular components with free-living ciliates. Here, we performed a Tetrahymena-based transcriptomic screen to uncover novel exocytic factors in Ciliata and Apicomplexa. We identified membrane-bound proteins, named CRMPs, forming part of a large complex essential for rhoptry secretion and invasion in Toxoplasma. In contrast to previously described rhoptry exocytic factors, TgCRMPs are not required for the assembly of the rhoptry secretion machinery and only transiently associated with the exocytic site - prior to invasion. CRMPs and their partners contain putative host cell-binding domains, and CRMPa shares similarity to GPCR proteins. We propose that the CRMP complex acts as host-molecular sensor to ensure that rhoptry exocytosis occurs when the parasite contacts the host cell.

cell biology↗