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Ear Development (ear + development)

Distribution by Scientific Domains
Life Sciences100%

Kinds of Ear Development

  • inner ear development
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    Selected Abstracts

    Dan is required for normal morphogenesis and patterning in the developing chick inner ear

    DEVELOPMENT GROWTH & DIFFERENTIATION, Issue 1 2007
    Takahiro Yamanishi
    During vertebrate inner ear development, compartmentalization of the auditory and vestibular apparatuses along two axes depends on the patterning of transcription factors expressed in a region-specific manner. Although most of the patterning is regulated by extrinsic signals, it is not known how Nkx5.1 and Msx1 are patterned. We focus on Dan, the founding member of the Cerberus/Dan gene family that encodes BMP antagonists, and describe its function in morphogenesis and patterning. First, we confirmed that Dan is expressed in the dorso-medial region of the otic vesicle that corresponds to the presumptive endolymphatic duct and sac (ed/es). Second, we used siRNA knockdown to demonstrate that depletion of Dan induced both a severe reduction in the size of the ed/es and moderate deformities of the semicircular canals and cochlear duct. Depletion of Dan also caused suppression of Nkx5.1 in the dorso-lateral region, suppression of Msx1 in the dorso-medial region, and ectopic induction of Nkx5.1 and Msx1 in the ventro-medial region. Most of these phenotypes also appeared following misexpression of the constitutively active form of BMP receptor type Ib. Thus, Dan is required for the normal morphogenesis of the inner ear and, by inhibiting BMP signaling, for the patterning of the transcription factors Nkx5.1 and Msx1. [source]

    Chondrocyte-specific Smad4 gene conditional knockout results in hearing loss and inner ear malformation in mice

    DEVELOPMENTAL DYNAMICS, Issue 8 2009
    Shi-Ming Yang
    Abstract Smad4 is the central intracellular mediator of transforming growth factor-, (TGF-,) signaling, which plays crucial roles in tissue regeneration, cell differentiation, embryonic development, and regulation of the immune system. Conventional Smad4 gene knockout results in embryonic lethality, precluding its use in studies of the role of Smad4 in inner ear development. We used chondrocyte-specific Smad4 knockout mice (Smad4Co/Co) to investigate the function of Smad4 in inner ear development. Smad4Co/Co mice were characterized by a smaller cochlear volume, bone malformation, and abnormalities of the osseous spiral lamina and basilar membrane. The development of the hair cells was also abnormal, as evidenced by the disorganized stereocilia and reduced density of the neuronal processes beneath the hair cells. Auditory function tests revealed the homozygous Smad4Co/Co mice suffered from severe sensorineural hearing loss. Our results suggest that Smad4 is required for inner ear development and normal auditory function in mammals. Developmental Dynamics, 2009. © 2009 Wiley-Liss, Inc. [source]

    Diverse expression patterns of LIM-homeodomain transcription factors (LIM-HDs) in mammalian inner ear development

    DEVELOPMENTAL DYNAMICS, Issue 11 2008
    Mingqian Huang
    Abstract LIM-homeodomain transcription factors (LIM-HDs) are essential in tissue patterning and differentiation. But their expression patterns in the inner ear are largely unknown. Here we report on a study of twelve LIM-HDs, by their tempo-spatial patterns that imply distinct yet overlapping roles, in the developing mouse inner ear. Expression of Lmx1a and Isl1 begins in the otocyst stage, with Lmx1a exclusively in the non-sensory and Isl1 in the prosensory epithelia. The second wave of expression at E12.5 includes Lhx3, 5, 9, Isl2, and Lmx1b in the differentiating sensory epithelia with cellular specificities. With the exception of Lmx1a and Lhx3, all LIM-HDs are expressed in ganglion neurons. Expression of multiple LIM-HDs within a cell type suggests their redundant function. Developmental Dynamics 237:3305,3312, 2008. © 2008 Wiley-Liss, Inc. [source]

    Comparative analysis of Gata3 and Gata2 expression during chicken inner ear development

    DEVELOPMENTAL DYNAMICS, Issue 1 2007
    Kersti Lilleväli
    Abstract The inner ear is a complex sensory organ with hearing and balance functions. Gata3 and Gata2 are expressed in the inner ear, and to gain more insight into their roles in otic development, we made a detailed expression analysis in chicken embryos. At early stages, their expression was highly overlapping. At later stages, Gata2 expression became prominent in vestibular and cochlear nonsensory epithelia. In contrast to Gata2, Gata3 was mainly expressed in the developing sensory epithelia, reflecting the importance of this factor in the sensory,neural development of the inner ear. While the later expression patterns of both Gata3 and Gata2 were highly conserved between chicken and mouse, important differences were observed especially with Gata3 during early otic development, providing indications of divergent molecular control during placode invagination in mice and chickens. We also found indications that the regulatory hierarchy observed in mouse, where Gata3 is upstream of Gata2 and Fgf10, could be conserved in chicken. Developmental Dynamics 236:306,313, 2007. © 2006 Wiley-Liss, Inc. [source]

    Groucho corepressor proteins regulate otic vesicle outgrowth

    DEVELOPMENTAL DYNAMICS, Issue 3 2005
    Baubak Bajoghli
    Abstract The Groucho/Tle family of corepressor proteins is known to regulate multiple developmental pathways. Applying the dominant-negative effect of the short member Aes, we demonstrate here a critical role of this gene family also for ear development. Misexpression of Aes in medaka embryos resulted in reduced size or loss of otic vesicles, whereas overexpression of the full-length Groucho protein Tle4 gave the opposite phenotype. These results are in close agreement with phenotypes observed for eye formation, suggesting a similar role for Groucho/Tle proteins in the developmental pathways of both sensory organs. Furthermore, by using the heat-inducible HSE promoter, we observed reversible branching of the embryonic axis upon Aes misexpression, indicating a transient duplication of the organizer. Groucho proteins, therefore, are critical for organizer maintenance. Developmental Dynamics 233:760,771, 2005 © 2005 Wiley-Liss, Inc. [source]

    Molecular characterization of conditionally immortalized cell lines derived from mouse early embryonic inner ear

    DEVELOPMENTAL DYNAMICS, Issue 4 2004
    John A. Germiller
    Abstract Inner ear sensory hair cells (HCs), supporting cells (SCs), and sensory neurons (SNs) are hypothesized to develop from common progenitors in the early embryonic otocyst. Because little is known about the molecular signals that control this lineage specification, we derived a model system of early otic development: conditionally immortalized otocyst (IMO) cell lines from the embryonic day 9.5 Immortomouse. This age is the earliest stage at which the otocyst can easily be separated from surrounding mesenchymal, nervous system, and epithelial cells. At 9.5 days post coitum, there are still pluripotent cells in the otocyst, allowing for the eventual identification of both SN and HC precursors,and possibly an elusive inner ear stem cell. Cell lines derived from primitive precursor cells can also be used as blank canvases for transfections of genes that can affect lineage decisions as the cells differentiate. It is important, therefore, to characterize the "baseline state" of these cell lines in as much detail as possible. We characterized seven representative "precursor-like" IMO cell populations and the uncloned IMO cells, before cell sorting, at the molecular level by polymerase chain reaction (PCR) and immunocytochemistry (IHC), and one line (IMO-2B1) in detail by real-time quantitative PCR and IHC. Many of the phenotypic markers characteristic of differentiated HCs or SCs were detected in IMO-2B1 proliferating cells, as well as during differentiation for up to 30 days in culture. These IMO cell lines represent a unique model system for studying early stages of inner ear development and determining the consequences of affecting key molecular events in their differentiation. Developmental Dynamics 231:815,827, 2004. © 2004 Wiley-Liss, Inc. [source]

    Differential expression of Na,K-ATPase , and , subunit genes in the developing zebrafish inner ear

    DEVELOPMENTAL DYNAMICS, Issue 3 2003
    Brian Blasiole
    Abstract We have used whole-mount in situ hybridization to analyze Na,K-ATPase , and , subunit gene expression in the developing zebrafish ear. Four ,1-like (,1a.1, ,1a.2, ,1a.4, and ,1a.5) and two , (,1a and ,2b) subunit genes are expressed in ear beginning at mid-somitogenesis. Each gene exhibits a distinct spatial and temporal expression pattern. The ,1a.1 gene was ubiquitously expressed in the otic epithelium from mid-somitogenesis to 24 hr postfertilization (hpf). Expression of this gene was gradually reduced and by 48 hpf, ,1a.1 transcripts were no longer detectable in the ear. The ,1a.2 and ,1a.5 genes were expressed in regions that correspond to the anterior macula, lateral crista, and semicircular canal projections up to 48 hpf. At later stages, expression of these genes was limited to cells in the dorsolateral septum and semicircular canal projections. ,1a.4 and ,1a transcripts were ubiquitously expressed during ear development and were present in most otic tissues at 5 days postfertilization (dpf). Expression of the ,2b gene, on the other hand, was restricted to subsets of cells that form sensory epithelia. These results strongly suggest different functional roles for individual Na,K-ATPase genes in zebrafish ear development. Na,K-ATPase genes are likely to represent useful markers for the analysis of zebrafish otogenesis. Development Dynamics, 2003. © 2003 Wiley-Liss, Inc. [source]

    Neuronal calcium sensor-1 gene ncs-1a is essential for semicircular canal formation in zebrafish inner ear

    DEVELOPMENTAL NEUROBIOLOGY, Issue 3 2005
    Brian Blasiole
    Abstract We have analyzed the functional role of neuronal calcium sensor-1 (Ncs-1) in zebrafish development. We identified two orthologs of the mammalian NCS-1 gene. Full-length cDNAs encoding zebrafish Ncs-1a and Ncs-1b polypeptides were cloned and characterized. Whole-mount in situ hybridization revealed that ncs-1a mRNA was expressed beginning at early somitogenesis. As development progressed, ncs-1a mRNA was present throughout the embryo with expression detected in ventral hematopoietic mesoderm, pronephric tubules, CNS nuclei, and otic vesicle. By 4.5 days post fertilization (dpf), ncs-1a expression was detected primarily in the brain. Expression of ncs-1b mRNA was first detected at 36 hours post fertilization (hpf) and was restricted to the olfactory bulb. By 4.5 dpf, ncs-1b was expressed at low levels throughout the brain. Knockdown of ncs-1a mRNA translation with antisense morpholinos blocked formation of semicircular canals. These studies identify a novel function for ncs-1a in inner ear development and suggest that this calcium sensor plays an important role in vestibular function. © 2005 Wiley Periodicals, Inc. J Neurobiol, 2005 [source]