As with any substantial application package, the ASPIRE project needed a convenient way to specify configuration settings pertaining to different parts of the computational pipeline.
What follows below are some outlines from our attempts to tackle this configuration issue. Where a supplementary (and hopefully useful) nugget is provided, or a caveat discussed, I shall append a linked numeral, like so: (n)
A brief background of ASPIRE
ASPIRE is a Python (3.6) package under development, which ingests Micrographs, the output of Cryo-Electron Microscopy (images that closely resemble television static), and comes up with a 3D reconstruction of the molecule. Read the excellent writeup on the ASPIRE page for a more comprehensive review of the package.
APPLE-Picker is a submodule of ASPIRE Python package in development for reconstructing a 3D CryoEM map of biomolecule from corresponding 2D particle images, developed by the researchers in Professor Amit Singer’s group. It is an automatic tool to select millions of particles from thousands of micrographs, a critical step in the pipeline of CryoEM image reconstruction. It used to be performed manually but can be very tedious and difficult especially for small particles with low contrast (low signal-noise ratio). The CPU version takes ~80 seconds on average to finish processing one micrograph. To achieve the goal of finishing thousands of micrographs in a few minutes, we need an alternative method, such as GPU accelerating.
2019 Princeton GPU Hackathon
Princeton university held its first GPU hackathon on campus this summer from June 24 to 28, organized and hosted by the Princeton Institute for Computational Science and Engineering (PICSciE), and co-sponsored by NVIDIA and the Oak Ridge Leadership Computing Facility (OLCF). The main goal of this Hackathon was to port research codes to GPUs or optimize them with the help of experts from industry, academia and national labs, as emphasized by Ian Cosden, one of lead organizers and manager of Princeton’s Research Software Engineering Group. This blog reports our attempts and the story behind accelerating APPLE-Picker using GPU and parallel computing in Python.
Background on ASPIRE (Algorithms for Single Particle Reconstruction)
Significant progress on computational algorithms and software is one of the major reasons leading the revolution of resolution in three dimensional structure determination of biomolecules using CryoEM, a technique projecting rapidly frozen and randomly orientated 3D particles into 2D noisy images on micrographs and reconstructing 3D density maps in atomistic resolution through computer software. Due to many crucial roles of 3D biomolecules such as protein enzymes for further study in structural and chemical biology, biophysics, biomedical and other related fields, the 2017 Nobel prize in chemistry was awarded to three scholars for significantly advancing the CryoEM technique as explained in this Youtube video.
During the past 10 years, Professor Amit Singer’s group has proposed many new ideas in various numerical algorithms and developed the ASPIRE Matlab package to tackle many problems involved in reconstructing a 3D CryoEM map of biomolecule from corresponding 2D particle images, including CTF estimation, denoising, particle picking, 2D and 3D classification, and ab initio 3D reconstruction.