Even though chondrichthyans (cartilaginous fish like sharks and rays) are crucial to understanding vertebrate evolution, studying their genetics has been difficult because they are large, slow growing, and take a long time to reproduce compared to common laboratory models like mice.
However, recent technological advances have made it possible to generate high-quality genomic data even for these ‘non-model’ species, enabling the exploration of new areas of genetics, developmental biology, physiology, neuroscience, and evolutionary biology. And as Bangor is located by the Menai Strait, and has easy access to the shore, staff in the School of Environmental & Natural Sciences have ready access to a type of shark called the lesser spotted catshark (Scyliorhinus canicula).
The lesser spotted catshark (sometimes called the dogfish) is a great model for studying how different cell types and organs evolved in vertebrates due to its relatively small size, easy accessibility, and evolutionary significance. Since sharks have large organs, often comparable in size to those of humans, these findings can be more applicable to our understanding of human development and disease than those from many other species. Sharks also have several interesting unique features, like the ability to replace their teeth throughout their life, an unusual way of coping with the stresses of an aquatic lifestyle through high levels of urea in their tissues, and slow rates of mutation.
New techniques like single-cell sequencing approaches are transforming our understanding of how cells develop and function in humans, mice, and other model species, but until now have been impossible to apply to sharks because of the lack of high-quality genomic resources. Dr John Mulley and Dr Owen Osborne from the School of Environmental & Natural Sciences were both involved in an international effort to sequence, assemble, and analyse the catshark genome, which was completed as part of the ‘Darwin Tree of Life Project’ – an effort to sequence the complete genome of every species in the UK. The catshark was chosen as one of the initial 25 species that represented key areas of biodiversity in Britain to start the project in the ‘25 Genomes for 25 Years’ aspect of the Wellcome Sanger Institute's wider 25th Anniversary celebrations.
Dr John Mulley, Senior Lecturer in Zoology, said: “The catshark is one of the best model species for studying sharks,and this new genome sequence has already provided insight into shark genomes, the evolution of vertebrate sensory structures, and the population genetics of the species through comparison of DNA sequences from North Wales, the English Channel, and the Mediterranean. We’re now looking forward to using it as we study a range of interesting aspects of shark biology of relevance to human health, such as pancreas development and function; response to cardiac damage; and nervous system function and spinal cord injury.”
