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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/7793

Title: Wavelets filtering for classification of very noisy electron microscopic single particles images- application on structure determination of VP5-VP19C recombinant
Authors: Saad, Ali Samir
Keywords: Images
Electron microscope
Frozen hydrated
Medical Sciences
Issue Date: Dec-2003
Publisher: BioMed Central Ltd.
Citation: BMC Structural Biology: 3(9)
Abstract: Background: Images of frozen hydrated [vitrified] virus particles were taken close-to-focus in an electron microscope containing structural signals at high spatial frequencies. These images had very low contrast due to the high levels of noise present in the image. The low contrast made particle selection, classification and orientation determination very difficult. The final purpose of the classification is to improve the signal-to-noise ratio of the particle representing the class, which is usually the average. In this paper, the proposed method is based on wavelet filtering and multiresolution processing for the classification and reconstruction of this very noisy data. A multivariate statistical analysis (MSA) is used for this classification. Results: The MSA classification method is noise dependant. A set of 2600 projections from a 3D map of a herpes simplex virus -to which noise was added- was classified by MSA. The classification shows the power of wavelet filtering in enhancing the quality of class averages (used in 3D reconstruction) compared to Fourier band pass filtering. A 3D reconstruction of a recombinant virus (VP5-VP19C) is presented as an application of multi-resolution processing for classification and reconstruction. Conclusion: The wavelet filtering and multi-resolution processing method proposed in this paper offers a new way for processing very noisy images obtained from electron cryo-microscopes. The multi-resolution and filtering improves the speed and accuracy of classification, which is vital for the 3D reconstruction of biological objects. The VP5-VP19C recombinant virus reconstruction presented here is an example, which demonstrates the power of this method. Without this processing, it is not possible to get the correct 3D map of this virus.
URI: 10.1186/1472-6807-3-9
ISSN: 1472-6807
Appears in Collections:College of Applied Medical Sciences

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