title: Changes in the regulation of cortical neurogenesis contribute to encephalization during amniote brain evolution.
abstract: The emergence of larger brains with large numbers of neurons is an evolutionary innovation in mammals and birds. However, the corresponding changes in cortical developmental programmes during amniote evolution are poorly understood. Here we examine the cortical development of Madagascar ground geckos, and report unique characteristics of their reptilian cortical progenitors. The rates of proliferation and neuronal differentiation in the gecko cortex are much lower than those in other amniotes. Notch signalling is highly activated in the gecko cortical progenitors, which provides a molecular basis for the low rate of cortical neurogenesis. Interestingly, multiple neuron subtypes are sequentially generated in the gecko cortex, similar to other amniotes. These results suggest that changes in the regulation of cortical neural progenitors have accelerated neurogenesis and provided encephalization in mammalian and archosaurian lineages. In addition, the temporal regulation for making cortical neuronal subtypes has evolved in a common ancestor(s) of amniotes.
authors.affiliation: Department of Developmental Neurobiology, Kyoto Prefectural University of Medicine, Nishitakatsukasa-cho 13, Taisyogun, Kita-ku, Kyoto 603-8334, Japan. tadnom@koto.kpu-m.ac.jp
authors.forename: Tadashi
authors.initials: T
authors.lastname: Nomura
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Gotoh
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Ono
mesh_terms: D000818:Animals; D005075:Biological Evolution; D002453:Cell Cycle / Q000235:genetics; D002454:Cell Differentiation; D049109:Cell Proliferation; D002540:Cerebral Cortex / Q000166:cytology / Q000378:metabolism*; D002642:Chick Embryo / Q000196:embryology / Q000378:metabolism; D005260:Female; D018507:Gene Expression Regulation, Developmental; D008116:Lizards / Q000196:embryology / Q000378:metabolism*; D008297:Male; D051379:Mice / Q000196:embryology / Q000378:metabolism; D058953:Neural Stem Cells / Q000166:cytology / Q000378:metabolism*; D055495:Neurogenesis; D009474:Neurons / Q000145:classification / Q000166:cytology / Q000378:metabolism*; D051880:Receptors, Notch / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D014426:Turtles / Q000196:embryology / Q000378:metabolism
chemical_list: D051880:Receptors, Notch