The authors are grateful to the Council of Scientific and Industrial Research (CSIR), India, for financial support and encouragement, and to the staff of the Centre for Cellular and Molecular Biology (CCMB), Hyderabad, India, for providing instrumentation assistance to this study. We also thank Dr. Sunil K. Verma (CCMB, Hyderabad, India) for reviewing this manuscript. NM gratefully acknowledges the CSIR-JRF/NET Research Fellowship. SKS planned the research theme, designed the methods and experiments, discussed analyses, interpretation and presentation.