To the extent possible under law, AOP-Wiki has waived all copyright and related or neighboring rights to KE:1930
Key Event Title
altered, inner ear development
|Level of Biological Organization|
Key Event Components
|otic vesicle formation||abnormal|
Key Event Overview
AOPs Including This Key Event
|AOP Name||Role of event in AOP||Point of Contact||Author Status||OECD Status|
|GSK3beta inactivation leads to increased mortality||KeyEvent||Cataia Ives (send email)||Open for citation & comment|
Key Event Description
The zebrafish (Danio rerio), a genetically tractable vertebrate, lends itself particularly well as a model system in which to study the ear. Zebrafish do not possess outer or middle ears, but have a fairly typical vertebrate inner ear, the normal development and anatomy of which has been described in a series of atlas-type papers (Haddon and Lewis, 1996; Bang, Sewell and Malicki, 2001). Although the zebrafish ear does not contain a specialized hearing organ—there is no equivalent of the mammalian cochlea—many features are conserved with other vertebrate species (Whitfield, 2002).
Inner ear develops from an ectodermal thickening, the otic placode, visible on either side of the hindbrain from mid-somite stages. In the zebrafish, this placode cavitates to form a hollow ball of epithelium, the otic vesicle, from which all structures of the membranous labyrinth and the neurons of the statoacoustic (VIIIth) ganglion arise (Haddon and Lewis, 1996; Whitfield et al., 2002).
The mature organ, found in all jawed vertebrates, has two functions: it serves as an auditory system, which detects sound waves, and as a vestibular system, which detects linear and angular accelerations, enabling the organism to maintain balance (Whitfield et al., 1996).
How It Is Measured or Detected
- Direct observation of internal anatomic structures of zebrafish embryos. Defects visible under the dissecting microscope (Whitfield, 2002)
- Comparison of swimming patterns with wild-type fish. Dog-eared embryos are less responsive to vibrational stimuli, fail to maintain balance when swimming, and may circle when disturbed, a behavior characteristic of fish with vestibular defects (Nicolson et al., 1998)
- High-throughput behavioral screening method for detecting auditory response defects in zebrafish. Assay monitors a rapid escape reflex in response to a loud sound (Bang et al., 2002).
Domain of Applicability
Evidence was provided for Zebrafish, Chick and Mouse (Whitfield, 2015)
Bang, P. I. et al. (2002) ‘High-throughput behavioral screening method for detecting auditory response defects in zebrafish’, Journal of Neuroscience Methods, 118(2), pp. 177–187. doi: 10.1016/S0165-0270(02)00118-8.
Bang, P. I., Sewell, W. F. and Malicki, J. J. (2001) ‘Morphology and cell type heterogeneities of the inner ear epithelia in adult and juvenile zebrafish (Danio rerio)’, Journal of Comparative Neurology, 438(2), pp. 173–190. doi: 10.1002/cne.1308.
Haddon, C. and Lewis, J. (1996) ‘Early ear development in the embryo of the zebrafish, Danio rerio’, Journal of Comparative Neurology, 365(1), pp. 113–128. doi: 10.1002/(SICI)1096-9861(19960129)365:1<113::AID-CNE9>3.0.CO;2-6.
Nicolson, T. et al. (1998) ‘Genetic analysis of vertebrate sensory hair cell mechanosensation: The zebrafish circler mutants’, Neuron, 20(2), pp. 271–283. doi: 10.1016/S0896-6273(00)80455-9.
Uribe, P. M. et al. (2013) ‘Aminoglycoside-Induced Hair Cell Death of Inner Ear Organs Causes Functional Deficits in Adult Zebrafish (Danio rerio)’, PLoS ONE, 8(3), p. 58755. doi: 10.1371/journal.pone.0058755.
Whitfield, T. T. et al. (1996) ‘Mutations affecting development of the zebrafish inner ear and lateral line’, Development, 123, pp. 241–254. doi: 10.1242/dev.123.1.241.
Whitfield, T. T. et al. (2002) ‘Development of the zebrafish inner ear’, Developmental Dynamics, 223(4), pp. 427–458. doi: 10.1002/dvdy.10073.
Whitfield, T. T. (2002) ‘Zebrafish as a Model for Hearing and Deafness’, J Neurobiol, 53, pp. 157–171. doi: 10.1002/neu.10123.
Whitfield, T. T. (2015) ‘Development of the inner ear’, Current Opinion in Genetics and Development, 32, pp. 112–118. doi: 10.1016/j.gde.2015.02.006.