Zebrafish Inner Ear Development and Function

Baxendale, Sarah; Whitfield, Tanya T.

doi:10.1016/b978-0-12-408088-1.00003-8

Cited by 8 publications

(10 citation statements)

References 149 publications

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“…The proportion of immediate response and delayed response for three genotypes were shown in Figure b. As described previously (Baxendale et al, ), the successful C‐startle was identified excluding delayed response, so the probability of C‐startle response for wild‐type and heterozygous larvae was indistinguishable and significantly higher than that of homozygous mutants (Figure c). Overall, the averaged C‐startle response time of homozygous mutant larvae was significantly increased, compared to that of wild‐type and heterozygous larvae, consistent to notion that low cldn7b expression level accounted for otic defects in developing homozygous mutant ears.…”

Section: Resultssupporting

confidence: 53%

“…To see if the observed embryonic ear defects affected ear function of homozygous mutant larvae, C‐startle response experiment was performed (Baxendale, Whitfield, Romand, & Varela‐Nieto, ). At 5 dpf, wild‐type and heterozygous mutant larvae could immediately respond to near‐field pure tone stimulation within 4 ms, but homozygous mutant larvae either had a delayed response at 8 ms or no response at all (Figure a).…”

Section: Resultsmentioning

confidence: 99%

“…Inner ear hair cells are responsible for converting vibration sensation or mechanical stress to electrical/chemical signals that initiate auditory or vestibular circuitry (Baxendale et al, ). Although majority (∼80%) of homozygous cldn7b mutant larvae showed normal otolith number and semicircular canals in the ear at 5 dpf (Figures c and d), suggesting a recovery from early abnormal otic development, some homozygous mutants exerted delayed C‐startle response (Figure ) might point out the possibility that early development of hair cells was affected in the homozygous mutant ears.…”

Section: Resultsmentioning

confidence: 99%

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Claudin7b is required for the formation and function of inner ear in zebrafish

Song

Zhao

et al. 2017

Journal Cellular Physiology

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Zebrafish has become an excellent model for studying the development and function of inner ear. We report here a zebrafish line in which claudin 7b (cldn7b) locus is interrupted by a Tol2 transposon at its first intron. The homozygous mutants have enlarged otocysts, smaller or no otoliths, slowly formed semicircular canals, and insensitiveness to sound stimulation. These abnormal phenotypes and hearing loss of inner ear could be mostly rescued by injection of cldn7b-mRNA into one-cell stage homozygous mutant embryos. Mechanistically, cldn7b-deficiency interrupted the formation of apical junction complexes (AJCs) in otic epithelial cells of inner ear and the ion-homeostasis of endolymph, which then led to the loss of proper contact between otoliths and normally developed hair cells in utricle and saccule or aberrant mechanosensory transduction. Thus, Cldn7b is essential for the formation and proper function of inner ear through its unique role in keeping an initial integrity of otic epithelia during zebrafish embryogenesis.

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Section: Resultssupporting

confidence: 53%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Claudin7b is required for the formation and function of inner ear in zebrafish

Song

Zhao

et al. 2017

Journal Cellular Physiology

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“…The lagena is the last to emerge during ontogeny (e.g. Bever & Fekete, ; Baxendale & Whitfield, ) as an appendix of the saccule (for an overview see illustrations in Retzius, ). The different timing of the formation of saccular and lagenar otoliths might facilitate the mineralization of two different calcium carbonate polymorphs within two interconnected – but to some extent spatially separated – otolith end organs.…”

Section: Functional Morphologymentioning

confidence: 99%

Enigmatic ear stones: what we know about the functional role and evolution of fish otoliths

et al. 2018

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Otoliths in bony fishes play an important role in the senses of balance and hearing. Otolith mass and shape are, among others, likely to be decisive factors influencing otolith motion and thus ear functioning. Yet our knowledge of how exactly these factors influence otolith motion is incomplete. In addition, experimental studies directly investigating the function of otoliths in the inner ear are scarce and yield partly conflicting results. Herein, we discuss questions and hypotheses on how otolith mass and shape, and the relationship between the sensory epithelium and overlying otolith, influence otolith motion. We discuss (i) the state‐of‐the‐art knowledge regarding otolith function, (ii) gaps in knowledge that remain to be filled, and (iii) future approaches that may improve our understanding of the role of otoliths in ear functioning. We further link these functional questions to the evolution of solid teleost otoliths instead of numerous tiny otoconia as found in most other vertebrates. Until now, the selective forces and/or constraints driving the evolution of solid calcareous otoliths and their diversity in shape in teleosts are largely unknown. Based on a data set on the structure of otoliths and otoconia in more than 160 species covering the main vertebrate groups, we present a hypothetical framework for teleost otolith evolution. We suggest that the advent of solid otoliths may have initially been a selectively neutral ‘by‐product’ of other key innovations during teleost evolution. The teleost‐specific genome duplication event may have paved the way for diversification in otolith shape. Otolith shapes may have evolved along with the considerable diversity of, and improvements in, auditory abilities in teleost fishes. However, phenotypic plasticity may also play an important role in the creation of different otolith types, and different portions of the otolith may show different degrees of phenotypic plasticity. Future studies should thus adopt a phylogenetic perspective and apply comparative and methodologically integrative approaches, including fossil otoliths, when investigating otoconia/otolith evolution and their function in the inner ear.

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“…This hardly covers the tremendous morphological diversity in fishes (see e.g., Baxendale and Whitfield, 2014;Alderks and Sisneros, 2013). Another issue is to unravel the linkage between ear morphology and ear function.…”

Section: Modified Otolith End Organs In Teleostsmentioning

confidence: 99%

Diversity in Fish Auditory Systems: One of the Riddles of Sensory Biology

2016

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An astonishing diversity of inner ears and accessory hearing structures (AHS) that can enhance hearing has evolved in fishes. Inner ears mainly differ in the size of the otolith end organs, the shape and orientation of the sensory epithelia, and the orientation patterns of ciliary bundles of sensory hair cells. Despite our profound morphological knowledge of inner ear variation, two main questions remain widely unanswered. (i) What selective forces and/or constraints led to the evolution of this inner ear diversity? (ii) How is the morphological variability linked to hearing abilities? Improved hearing is mainly based on the ability of many fish species to transmit oscillations of swim bladder walls or other gas-filled bladders to the inner ears. Swim bladders may be linked to the inner ears via a chain of ossicles (in otophysans), anterior extensions (e.g., some cichlids, squirrelfishes), or the gas bladders may touch the inner ears directly (labyrinth fishes). Studies on catfishes and cichlids demonstrate that larger swim bladders and more pronounced linkages to the inner ears positively affect both auditory sensitivities and the detectable frequency range, but lack of a connection does not exclude hearing enhancement. This diversity of auditory structures and hearing abilities is one of the main riddles in fish bioacoustics research. Hearing enhancement might have evolved to facilitate intraspecific acoustic communication. A comparison of sound-producing species, however, indicates that acoustic communication is widespread in taxa lacking AHS. Eco-acoustical constraints are a more likely explanation for the diversity in fish hearing sensitivities. Low ambient noise levels may have facilitated the evolution of AHS, enabling fish to detect low-level abiotic noise and sounds from con-and heterosopecifics, including predators and prey. Aquatic habitats differ in ambient noise regimes, and preliminary data indicate that hearing sensitivities of fishes vary accordingly.

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Zebrafish Inner Ear Development and Function

Cited by 8 publications

References 149 publications

Claudin7b is required for the formation and function of inner ear in zebrafish

Claudin7b is required for the formation and function of inner ear in zebrafish

Enigmatic ear stones: what we know about the functional role and evolution of fish otoliths

Diversity in Fish Auditory Systems: One of the Riddles of Sensory Biology

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