Andrew H A Clayton1, Amitabha Chattopadhyay2. 1. Centre for Microphotonics, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, Victoria, Australia. Electronic address: aclayton@swin.edu.au. 2. CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India. Electronic address: amit@ccmb.res.in.