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Evolution and development of the vertebrate earThis review outlines major aspects of development and evolution of the ear, specifically addressing issues of cell fate commitment and the emerging molecular governance of these decisions. Available data support the notion of homology of subsets of mechanosensors across phyla (proprioreceptive mechanosensory neurons in insects, hair cells in vertebrates). It is argued that this conservation is primarily related to the specific transducing environment needed to achieve mechanosensation. Achieving this requires highly conserved transcription factors that regulate the expression of the relevant structural genes for mechanosensory transduction. While conserved at the level of some cell fate assignment genes (atonal and its mammalian homologue), the ear has also radically reorganized its development by implementing genes used for cell fate assignment in other parts of the developing nervous systems (e.g., neurogenin 1) and by evolving novel sets of genes specifically associated with the novel formation of sensory neurons that contact hair cells (neurotrophins and their receptors). Numerous genes have been identified that regulate morphogenesis, but there is only one common feature that emerges at the moment: the ear appears to have co-opted genes from a large variety of other parts of the developing body (forebrain, limbs, kidneys) and establishes, in combination with existing transcription factors, an environment in which those genes govern novel, ear-related morphogenetic aspects. The ear thus represents a unique mix of highly conserved developmental elements combined with co-opted and newly evolved developmental elements.
Document ID
20040088735
Document Type
Reprint (Version printed in journal)
Authors
Fritzsch, B. (Creighton University Omaha, NE 68178, United States)
Beisel, K. W.
Date Acquired
August 21, 2013
Publication Date
August 1, 2001
Publication Information
Publication: Brain research bulletin
Volume: 55
Issue: 6
ISSN: 0361-9230
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: R01 DC04279
CONTRACT_GRANT: P01 DC00215
Distribution Limits
Public
Copyright
Other
Keywords
Review
Non-NASA Center
NASA Discipline Developmental Biology
Review, Tutorial