Characterizing Animal Development with Genetic Regulatory Mechanisms
Although developmental biology is an institutionalized discipline, no unambiguous account of what development is and when it stops has so far been provided. In this article, I focus on two sets of developmental molecular mechanisms, namely those underlying the heterochronic pathway in C. elegans and those involving Hox genes in vertebrates, to suggest a conceptual account of animal development. I point out that, in these animals, the early stages of life exhibit salient mechanistic features, in particular in the way mechanisms of genetic regulation occur in the organism. Indeed, these stages are characterized by sequential and irreversible changes in gene expression taking place throughout the organism. A general definition of animal development based on these distinctive features implies that, at least for some animal species, development does not go on throughout the life of the animal, contrary to what has recently been claimed by some biologists and philosophers. Instead, in such species, development encompasses various events occurring sequentially at the beginning of life.
KeywordsCaenorhabditis elegans Development Genetic regulatory mechanisms Heterochronic pathway Hox genes Vertebrates
I am grateful to Lucie Laplane, Michel Morange, Valérie Ngo-Muller, Antonine Nicoglou, Thomas Pradeu, and Michel Vervoort for fruitful discussions and critical reading of my manuscript.
- Davidson EH (2006) The regulatory genome. Academic Press, San DiegoGoogle Scholar
- Duboule D, Dollé P (1989) The structural and functional organization of the murine HOX gene family resembles that of Drosophila homeotic genes. EMBO J 8:1497–1505Google Scholar
- Gardiner DM, Blumberg B, Komine Y, Bryant SV (1995) Regulation of HoxA expression in developing and regenerating axolotl limbs. Development 121:1731–1741Google Scholar
- Gilbert SF (2010) Developmental biology. Sinauer Associates, SunderlandGoogle Scholar
- Laplane L (2011) Stem cells and the temporal boundaries of development: toward a species-dependent view. Biol Theory. doi: 10.1007/s13752-011-0009-z
- Morange M (2011) Development and aging. Biol Theory. doi: 10.1007/s13752-011-0010-6
- Oyama S, Griffiths PE, Gray RD (eds) (2001) Cycles of contingency: developmental systems and evolution. MIT Press, Cambridge, MAGoogle Scholar
- Pasquinelli AE, Reinhart BJ, Slack F, Martindale MQ, Kuroda MI, Maller B, Hayward DC, Ball EE, Degnan B, Müller P, Spring J, Srinivasan A, Fishman M, Finnerty J, Corbo J, Levine M, Leahy P, Davidson E, Ruvkun G (2000) Conservation of the sequence and temporal expression of let-7 heterochronic regulatory RNA. Nature 408:86–89CrossRefGoogle Scholar
- Vervoort M (2011) Regeneration and development in animals. Biol Theory. doi: 10.1007/s13752-011-0005-3