n hindsight, the training I received as an undergraduate at UNE was classical zoology, by which I mean that much of what I learned in the early 1960s was little different from the teaching of zoology at Cambridge University in the 1870s and 1880s. From my BSc (Hons) research searching for a particular type of cartilage (secondary cartilage) in the skulls of tiger snakes (Notechis scutatus), my PhD research on similar cartilages in chicken embryos, and until around 1974, my research focused on embryonic development, especially development of the skeleton. In the early 70s, I was invited to speak at a symposium on morphological changes in evolution to talk about my embryology research in an evolutionary context. It was the beginning of 35 years of research exploring the evolution and formation of skeletal tissues, particularly those of the face (and skull and gills in fish). It’s research that has, amongst other things, provided key clues to how bone is lost during inactivity or prolonged bed rest. That journey, part of which is outlined in a video clip filmed when I was inducted into the Hall of Fame of the Discovery Centre, has taken me into the embryos of animals as varied as birds, fish, frogs, salamanders, alligators, mammals, skates, squid and marine worms. It has taken me further back into early embryos to investigate the origin of the cells that form the skull and skeleton of the face. These cells — known as neural crest cells (NCCs) — arise at the edge of the developing brain and migrate throughout the developing head to form the skull, jaws, and skeleton supporting the eyes, ears and nose. Research on NCCs also has taken me back to evolutionary studies as we attempt to understand how the earliest vertebrates acquired NCCs from ancestors that did not have them. It has taken us to investigations of the molecular basis of NCC development and skeletal formation; and this for someone who never heard the letters DNA in any undergraduate lecture. Learning is lifelong.
You can see that I remain a comparative zoologist and my education at UNE prepared me for that role beautifully. We established one of the world’s few labs that combines embryologists, palaeontologists, and evolutionary biologists. Most recently, we have been using frog embryos. Why frogs? Because the tadpoles have a skeleton made entirely of cartilage while the adult frogs into which tadpoles transform have mostly a bony skeleton. We want to know how this transformation happens. Do the same cells make the tadpole cartilage as make the bone of the adults? A post-doctoral fellow in my laboratory, Ryan Kerney, generated transgenic frogs in which NCCs and future cartilage or bone cells are labeled. Frogs are slow to breed, so we continue to wait patiently for the next generation of transgenic animals. We are not idle as we wait. A new postdoctoral fellow, Andrew Gillis, is investigating the molecular control of the development of various types of skeletal tissues that form in the lower jaws of Atlantic salmon (Salmon salar) as they migrate upstream to breed. One of those tissues is secondary cartilage. A master’s student, Zabrina Prescott, is investigating fossil salmon to determine when secondary cartilage arose. A collaboration with one of the major dinosaur labs revealed that dinosaurs have secondary cartilage, further confirming the dinosaur origin of birds. Interests acquired in our youth are hard to give up; I have never lost the interest sparked at UNE in my 50-year fascination with skeletal development and evolution.
References available on request. Brian Hall was awarded the first D.Sc. in biological sciences from UNE in 1979. His other UNE qualifications include B.Sc (Hons) and PhD. He is currently University Research Professor Emeritus at Dalhousie University in Halifax Nova Scotia. His wife, June, received the University Medal upon graduation from UNE with her B.Sc (Hons)Zoology. The Nancie Priestley Memorial Prize, open annually to members of Mary White College, is named for her mother.
Secondary cartilage (in blue) formed in a fractured bone (red) in a several week-old chicken. The cartilage will either be replaced by bone and repair the fracture of the soft tissue in the middle or could form a false joint.
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