Department of Computational and Systems Biology, Genome Institute of Singapore, Singapore 138672 and Department of Computer Science, School of Computing, National University of Singapore, Singapore 117417.|Department of Computational and Systems Biology, Genome Institute of Singapore, Singapore 138672 and Department of Computer Science, School of Computing, National University of Singapore, Singapore 117417 Department of Computational and Systems Biology, Genome Institute of Singapore, Singapore 138672 and Department of Computer Science, School of Computing, National University of Singapore, Singapore 117417.