Search bioRxiv⌕ Search

bioRxiv · 10.1101/2020.06.16.155275

TranSPHIRE: Automated and feedback-optimized on-the-fly processing for cryo-EM

Abstract

Single particle electron cryomicroscopy (cryo-EM) requires full automation to allow high-throughput structure determination which is especially important for drug discovery research. Although several software packages exist where parts of the cryo-EM pipeline are automated, a complete solution that offers reliable, quality-optimized on-the-fly processing, resulting in a high-resolution three-dimensional reconstruction does not exist. Here we present TranSPHIRE: A software package for fully automated processing of cryo-EM data sets during data acquisition. TranSPHIRE transfers data from the microscope, automatically applies the common pre-processing steps, picks particles, performs 2D clustering, and 3D refinement parallel to image recording. Importantly, TranSPHIRE introduces a machine learning-based feedback loop to re-train its internally used picking model to adapt to any given data set live during processing. This elegant approach enables TranSPHIRE to process data more effectively, producing high-quality particle stacks. TranSPHIRE collects, and displays all microscope settings and metrics generated by its individual tools, in order to allow users to quickly evaluate data during acquisition. TranSPHIRE can run on a single work station and also includes the automated processing of filaments.

Source connections

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Stabrin, M., Schoenfeld, F., Wagner, T., Pospich, S., Gatsogiannis, C., Raunser, S.. 2020-06-17. TranSPHIRE: Automated and feedback-optimized on-the-fly processing for cryo-EM. https://doi.org/10.1101/2020.06.16.155275

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

Nanomechanical phenotyping uncovers a non-canonical smooth muscle-like hypercontractility program in lung squamous cell carcinoma myofibroblasts

Myofibroblast-like cancer-associated fibroblasts (myCAFs) drive the stiff, tumor-promoting microenvironment, yet their mechanical phenotype in non-small cell lung cancer (NSCLC) remains undefined. myCAFs from major NSCLC subtypes (lung adenocarcinoma (LUAD) and squamous cell carcinoma (LUSC)) were examined combining atomic force microscopy and traction force microscopy with molecular and signaling analyses. LUAD-myCAFs displayed canonical myofibroblast features, including elevated stiffness, traction forces, ROCK-MYPT1 signaling, and -SMA-rich stress fibers. Unexpectedly, LUSC-myCAFs amplified these nanomechanical features despite reduced ROCK-MYPT1 signaling and comparable -SMA levels. Instead, they exhibited a smooth muscle cell (SMC)-like contractile program characterized by enhanced SM-MHC(MYH11) expression colocalized with -SMA, ERK1/2-RLC hyperactivation, and DNA methylation reprogramming including SMC-contractility regulators. LUSC-myCAF hypercontractility was linked with reduced proliferative capacity and smaller intratumoral vessel lumens, consistent with the low CAF density and enhanced hypoxia patterns reported in LUSC. SMC markers were enriched and associated with adverse outcomes selectively in LUSC, highlighting the relevance of SMC-like myCAFs in LUSC progression. These findings unveil subtype-specific myCAF programs in NSCLC, and identify -SMA/SM-MHC(MYH11) myCAFs as key determinants of tumor mechanics, providing a rationale for the survival benefits of antihypertensive drugs targeting SMC hypercontractility. Moreover, they demonstrate that nanomechanical phenotyping can uncover translationally relevant myCAF phenotypes invisible to molecular profiling.

biophysics↗

Frequency-Dependent Structural Responses of Amyloid-β Fibrils to Terahertz Pulses: A Nonequilibrium Molecular Dynamics Study

The abnormal aggregation of amyloid proteins into fibrils is closely associated with several neurodegenerative diseases, highlighting the importance of developing effective strategies to modulate fibril structural stability. Here, we employed nonequilibrium molecular dynamics(NEMD) simulations to examine the effects of intense terahertz-to-mid-infrared pulses on three amyloid fibrils (2LMP, 2MXU, and 5OQV), focusing on the combined effects of pulse frequency and electric-field strength. Frequency scans from 0.5 to 60 THz in 0.5 THz steps revealed frequency-dependent losses of {beta}-sheet content, with several common response patterns in these fibrils. Comparisons at 2, 23, 33, and 50 THz showed that pulse-induced changes in secondary structure differed from those in high-temperature controls. Hydrogen-bond analysis showed that total hydrogen-bond counts could partially recover even as interchain hydrogen bonds continued to decrease, with distinct responses among representative chain pairs. We therefore propose a two-threshold electric-field framework for fibril disruption: Eth1 describes the onset of structural perturbation, whereas Eth2 indicates persistent structural loss after the pulse. This framework offers a testable approach for characterizing amyloid structural responses to external fields, although the underlying energy-coupling mechanisms, quantitative thresholds, and long-term recovery require further validation. These findings may provide a theoretical basis for exploring external-field-based strategies to modulate protein aggregation.

biophysics↗

Organised streaming of cerebrospinal fluid in the human third ventricle

Quasi-periodic pressure pulses associated with cardiac and respiratory activity generate reciprocating cerebrospinal fluid (CSF) motion in the human ventricles. Regular waves dominated by the cardiac cycle are overlaid with cycles of low-frequency respiratory waves, the latter to become stronger in forced breathing or even dominated by large successive flushes in NREM sleep. The present study investigates how such waves contribute to residual streaming within the human ventricles. Transient CFD simulations were performed in the third ventricle at varying parameters of frequency, stroke volume and wave-form asymmetry. Increasing the aqueduct peak Reynolds-number, either by small stroke volume and high frequency or large stroke volume at low frequency, transfers the flow from a reversible flow pattern to the formation of clear preferential pathways, alternating between the in- and outflow cycle. The resulting permanent streaming flux across the aqueduct relative to the mean oscillatory flow-rate, i.e. the dimensionless streaming ratio SR follows a rational saturation relation, SR [~] ReAq,peak/(C + ReAq,peak), demonstrating that increasing the peak aqueduct Reynolds number yields diminishing returns and bounds the relative contribution of residual inter-ventricular streaming. These findings demonstrate differences in hydrodynamic organisation in the third ventricle and highlight the importance of this organisation for intraventricular fluid exchange.

biophysics↗