Spatiotemporally exact cDNA libraries from quail embryos: A resource for studying neural crest development and neurocristopathies

The neural crest is of fundamental importance in the development of the head and peripheral nervous system, in the evolution of the vertebrates, and clinically because it gives rise to developmental abnormalities and neoplasms in humans. We have established a resource for studying the development of the neural crest by systematically constructing cDNA libraries from spatiotemporally exact neural crest and related cell populations. Neural crest populations were obtained from vagal and thoracic axial levels and from branchial arches, at premigratery and early and late migratory stages, at localization stages, and after differentiation into dorsal root ganglion cells, Schwann cells, sympathetic neurons, adrenal medullary cells, and melanocytes. Libraries were constructed using several methods developed to approach the issues of making representative libraries from small amounts of tissue. The fidelity and usefulness of the libraries were tested, and this revealed that they expressed a variety of sequences such as integrins, CAMs, growth factors and their receptors, protein- tyrosine kinases, and phosphatases. Differential display also revealed a unique combination of cDNA species. We then selected libraries spatio- temporally appropriate for epithelium-mesenchyme transformation and probed for TGF-β-related sequences. As anticipated, we confirmed the presence of TGF-β2 and dorsalin-1 but could not detect TGF-β1. We also revealed new expression sites, defined by the origin of the libraries, of receptors known to be expressed elsewhere (Tsk 7L; TBRII). We anticipate that this collection of cDNA libraries will be of use in studying normal and abnormal neural crest development, by both homology searches and differential expression approaches, with spatiotemporal expression information being inherent in the initial screen.