The people involved in chicken embryology at The Roslin Institute and a brief history of their research.
The Balic group produced the first transgenic chicken lines which allow specific sub-population of chicken immune cells to be visualised. The initial CSF1R-eGFP/RFP reporter lines enabled visualisation of cells of the chicken mononuclear phagocyte system, and more recently a RUNX1-eGFP which allows for visualisation of the majority of chicken immune cells, has been produced.
The Clinton group’s findings overturned a long-standing dogma and demonstrated that a system of sex chromosome dosage compensation operated in birds. They were also the first group to demonstrate that gynandromorph birds were composed of normal diploid male and female cells. This helped to establish that the mechanisms and factors that regulate gonadal development and the development of the sexual phenotype differ between mammals and birds. They have now shown that, unlike mammals, avian somatic cells possess a cell-autonomous sex identity (CASI), and that CASI is the major determinant in defining the sexual phenotype. They have identified a set of genes that are likely to represent the molecular signature underlying key differences between male and female birds in the function of the immune system and in the development of muscle mass. This group has also developed an in-ovo sexing assay that can identify the sex of chick embryos from nanolitre volumes of whole blood in under five minutes.
The Davey group’s research explores the embryonic events which create a patterned hand. Using naturally occurring avian mutants with abnormal limb formation, the Davey group has explored the fundament processes that contribute to the normal embryonic development of many organ systems including the limb, central nervous system, lung, liver and gut. This work includes the genetic mapping of the TALPID3 locus in both chickens and humans- an embryonic lethal ciliopathy, as well as determining the function of the TALPID3 protein. The genetic mapping and functional analysis of SHH enhancers to understand the genetic control of SHH expression and the anatomical (fate) mapping the developmental origin of the limb tissues. In particular the Davey Lab uses in ovo embryonic manipulations of avian embryos combined with gene expression analysis, comparative genomics and proteomics to study the regulation of the Hedgehog pathway- from initiation of expression through to pathway feedback and patterning consequences.
The Headon group identified the genetic basis for reduced feather coverage in the Naked neck and scaleless chicken breeds and defined how the products of these genes modulate cell behaviour in the embryonic skin. Using time-lapse imaging of cultured skin and modification of intercellular signalling this group has progressed understanding of how this tissue partitions itself into a periodic array of feathers over two days of incubation.
The McGrew group defined the minimum signals needed for the self-renewal of chicken germ cells and are applying these results to the propagation of germ cells from other avian species. They have used these cells to produce genetically modified chicken using DNA transposons and recently using gene editing vectors to investigate gene function during avian embryonic development. A knockout of the avian DDX4 gene showed that this gene was needed for oogenesis in birds. These sterile knockout chicken are being used as surrogate hosts for germ cells from poultry species with the goal of developing technologies for avian breed conservation.
The Rainger group has successfully revealed multiple novel genes that are required for normal eye development and growth, and has expanded our knowledge of what makes an eye. They use the chick eye as a model system as it possesses many unique advantages that are perfect for understanding the genetic, and molecular requirements of a developing and functioning eye, including size, accessibility, ease of manipulation and the well-annotated genome.
The Sang group has a broad focus on the development and application of technologies for genome engineering of the chicken. Lentiviral vectors have been used as the basis of an efficient method for transgene addition, including the production of lines in which green fluorescent protein and membrane-localised GFP are expressed ubiquitously in embryos that have been invaluable for transplantation/lineage tracing studies and in vivo imaging. Additional fluorescent protein reporter lines are being developed, including use of tissue-specific reporters (with the Balic group) and future plans will use gene editing approaches (with the McGrew group).