title: Heterochronic protein expression patterns in the developing embryonic chick cerebellum.
abstract: The advantages of the embryonic chick as a model for studying neural development range from the relatively low cost of fertilized eggs to the rapid rate of development. We investigated in ovo cerebellar development in the chick, which has a nearly identical embryonic period as the mouse (19-22 days). We focused on three antigens: Calbindin (CB), Zebrin II (ZII), and Calretinin (CR), and our results demonstrate asynchronous expression patterns during cerebellar development. Presumptive CB+ Purkinje cells are first observed at embryonic day (E)10 in clusters in posterior cerebellum. At E12, corresponding with global expression of CB across the cerebellum, Purkinje cells began to express ZII. By E14-E16, Purkinje cells disperse into a monolayer and develop a pattern of alternating immunopositive and immunonegative ZII stripes. CR is initially expressed by clusters of presumptive Purkinje cells in the nodular zone at E8. However, this expression is transient and at later stages, CR is largely confined to the granule and molecular layers. Before hatch (E18-E20), Purkinje cells adopt a morphologically mature phenotype with complex dendritic arborizations. Comparing this data to that seen in mice, we found that the sequence of Purkinje cell formation, protein expression, and development is similar in both species, but these events consistently begin ∼5-7 days earlier in the precocial chick cerebellum, suggesting an important role for heterochrony in neurodevelopment.
authors.affiliation: Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, 50 Stone Road, Guelph, Ontario, Canada.
authors.forename: E A
authors.initials: EA
authors.lastname: Gilbert
authors.forename: Y H
authors.initials: YH
authors.lastname: Lim
authors.forename: M K
authors.initials: MK
authors.lastname: Vickaryous
authors.forename: C L
authors.initials: CL
authors.lastname: Armstrong
mesh_terms: D000818:Animals; D064032:Calbindin 2; D064026:Calbindins; D002531:Cerebellum / Q000196:embryology* / Q000254:growth & development / Q000378:metabolism*; D002642:Chick Embryo; D018507:Gene Expression Regulation, Developmental; D051379:Mice; D009419:Nerve Tissue Proteins / Q000096:biosynthesis* / Q000235:genetics; D020543:Proteome / Q000235:genetics; D011689:Purkinje Cells / Q000378:metabolism; D064030:S100 Calcium Binding Protein G / Q000096:biosynthesis* / Q000235:genetics; D013045:Species Specificity
chemical_list: C576511:Calb2 protein, mouse; D064032:Calbindin 2; D064026:Calbindins; D009419:Nerve Tissue Proteins; D020543:Proteome; D064030:S100 Calcium Binding Protein G; C071871:zebrin II