Sudipto Roy obtained his Ph.D. from the National Centre for Biological Sciences in India, where he studied the cellular and genetic basis of muscle and neuronal development in the fruit fly, Drosophila. In 1998, he moved to the Centre for Developmental Genetics at the University of Sheffield, England, where he extended his studies to the analysis of induction and differentiation of muscle cell-types in the zebrafish embryo. Dr. Roy has been the recipient of several awards and fellowships from organizations that include the Company of Biologists, the Wellcome Trust, the Human Frontiers Science Program (HFSP) and the European Molecular Biology Organization (EMBO). In 2002, he was honoured with a Young Scientist Medal from the Indian National Science Academy. In the same year, he joined the IMCB as a Young Investigator, and has been an Assistant Professor and Principal Investigator since June 2003.

Among the most intriguing of questions that have attracted the attention of generations of biologists is how the fertilized egg, a single cell, is able to give rise to a complex organism with many well-differentiated tissues and organ systems. It is now clear that the development of plants and animals are guided by the activity of genes, whose protein products function in driving cells of the embryo to differentiate into distinct tissues. Although the genomes of several invertebrates, vertebrates and plants have now been completely sequenced, we have not fully understood what the function of each gene is, and how many genes can work together in networks to program development.

In our laboratory, we are interested in understanding the genetic basis of vertebrate development. For this, we are using the zebrafish embryo as it is uniquely amenable to many kinds of experimental manipulations. First, zebrafish embryos are optically transparent which allows direct visualization of embryogenesis under the microscope. Secondly, zebrafish have a relatively short life-cycle and produce eggs in large numbers. This allows us to perform large-scale genetic screens for mutations in genes that have essential roles in development. Most importantly, homologs of many zebrafish genes have now been shown to play conserved roles in humans, thus, making the zebrafish a highly suitable model organism for the study of the general principles that guide vertebrate development.

To highlight some of our achievements so far, we have discovered a gene called blimp1 that is required for the specification of a distinct lineage of muscle cells in the zebrafish embryo. These muscle cells, called the slow-twitch muscle cells, are present in all vertebrates, and allow sustained muscular activity through aerobic metabolism. Our studies have shown that blimp1 is not just necessary for slow muscle formation, but its activity is also sufficient for inducing naïve muscle cells to adopt the slow muscle fiber fate. To begin to uncover the cell biological and genetic basis of vertebrate myoblast fusion in vivo, we have analysed the fusion behaviour of myoblasts within the developing somites of the zebrafish embryo. Our study has provided evidence that the activity of Kirrel, a vertebrate homolog of immunoglobulin (Ig) domain-containing membrane receptors that organize myoblast fusion in Drosophila, is necessary for muscle precursor fusion in the zebrafish, thus, establishing an unexpected evolutionary conservation in the genetic control of myoblast fusion. In a separate line of investigation, we have identified the mechanism by which certain cells are able to differentiate specialized organelles called cilia. For example, in our own bodies, cells of the respiratory tract, the lining of the brain cavities and the spinal cord bear cilia. These cilia are motile and their movement is essential for the transport of fluid – like mucus in the respiratory tract and cerebrospinal fluid in the central nervous system. Our studies have shown that a forkhead domain containing transcription factor called Foxj1 both necessary as well as sufficient for controlling the expression of ciliary genes and for the biogenesis of motile cilia.

Besides normal development, we are also quite keen to understand the processes by which certain tissues are able to regenerate themselves in response to injury. In mammals, regenerative capacity is quite limited. By contrast, lower vertebrates like the zebrafish can regenerate many structures such as the heart, retina, fins as well as the spinal cord. Using regeneration of the zebrafish tail fin as a paradigm, we are making a systematic attempt to discover genes that are important for the initiation and progression of the regenerative process. We believe that our findings may have implications for regenerative medicine in the treatment of degenerative diseases and injuries in humans.