Abnormal Otoliths Research Articles

An anomalous otolith of Engraulis australis (Clupeiformes, Engraulidae) from the food of the Australasian gannet Morus serrator, New Zealand

ABSTRACT Saccular otoliths are hearing and balance structures in teleost fish and usually consist of the aragonite form of calcium carbonate but may contain varying amounts of the vaterite polymorph in abnormal cases. Environmental impacts, nutritional problems, pollution, stress, and changes in water parameters, or a combination of these factors, may cause deformities in saccular otoliths. In this study, we examined the morphologies and calcium carbonate polymorphs within abnormal and normal saccular otoliths in the anchovies Engraulis australis, retrieved from regurgitated stomach contents of the Australasian gannet Morus serrator, Hauraki Gulf, New Zealand. Scanning electron microscopy (SEM) and Raman microscopy revealed several prominences in numerous areas on the surfaces of abnormal otoliths. This is the first study to report on the morphology and compositional differences in abnormal otoliths retrieved from the food of a piscivorous bird in New Zealand. Abnormalities in the structure and composition of otoliths may impact balance and hearing functions in fish and have implications on their fitness. Further studies should explore whether such fish are preferentially targeted by their avian predators.

The Glutamine Synthetases Are Required for Sensory Hair Cell Formation and Auditory Function in Zebrafish.

The development of sensory hair cells (HCs) is closely linked to hearing loss. There are still many unidentified genes that may play a crucial role in HC development and function. Glutamine synthetase, Glul, is expressed in sensory hair cells and auditory organs. However, the role of the Glul gene family in the auditory system remains largely unexplored. This study aims to investigate the function of the Glul gene family in the auditory system. The expression patterns of the glul gene family were examined via in situ hybridization in zebrafish embryos. It was revealed that the expression of glula occurred in the otic vesicle, while glulb was expressed in the neuromast. In contrast, glulc did not exhibit any discernible signal. glula loss of function caused abnormal otolith formation and reduced hair cell number in otic vesicles, while glulb knockdown caused a decrease in HC number in both neuromasts and otic vesicles and impaired auditory function. Furthermore, we found that the knockdown of glulb induces apoptosis of hair cells. Transcriptomic analysis of zebrafish with glula and glulb knockdown revealed significant alterations in the expression of many genes associated with auditory organs. The current study sheds light on the requirement of glula and glulb in zebrafish hair cell formation and auditory function.

Scanning electron microscopy comparison of an abnormal and normal otoliths of the Anguilla anguilla collected from the Bafa Lake in Western Anatolia

AbstractAberrations in the otolith can harmfully influence the imperative actions of the fish species. The chief drive of the current investigation is to describe the deformities in the otoliths of the European eel Anguilla anguilla. Out of 76 Anguilla anguilla individuals collected from Bafa Lake in Western Anatolia, Türkiye, four female specimens exhibited abnormal otoliths. Scanning electron microscope was used to determine the deformed otoliths examined. The outcomes of the abnormality analyses in A. anguilla otoliths, deformities were noticed such as numerous prominence structures and bumps of different sizes on the surface of the otolith produced by buildup of the different crystal structures in some parts of the otolith. These deformities were found in the left and/or right otoliths of the female individuals of different total lengths. The percentage of individuals with abnormal otoliths of A. anguilla is calculated as 5.3%. The current study presents for the first‐time abnormal otolith information on left and right otoliths in female A. anguilla. Deformities in the otoliths of European eels are believed to result from a combination of genetic predisposition and stress caused by various environmental factors, such as water pollution, changes in salinity, temperature fluctuations and nutritional imbalances.

Presence of abnormal otoliths in hallucinogenic fish and their comparison with normal otoliths using light and scanning electron digital imaging.

The otolith organs located in the inner ear of the fish are responsible for vital activities such as balance and hearing. Abnormalities in these organs can adversely affect the vital activities of the fish species. The main purpose of the study is to analyze the abnormalities in the otoliths of Sarpa salpa, known as the hallucinogenic fish. For that, 372 individuals of S. salpa are collected from the North Aegean Sea. As a result of the abnormality analyses in S. salpa otoliths, anomalies were detected such as various prominence structures on the surface of the otolith caused by accumulation and a more transparent appearance due to the different crystal structures in some parts of the otolith. These abnormalities were found in the left and/or right otoliths of male and female individuals in different total lengths. The percentage of individuals with abnormal otoliths of S. salpa is calculated as 52.42%. It was determined that there are statistical differences between the left and right otolith measurements of male and female individuals with abnormal and normal otoliths(p < 0.05). There is no relationship between the percentage of individuals showing abnormality and total length and sex. The current study presents for the first time abnormal otolith information on left and right otoliths in male and female S. salpa. It is thought that abnormalities in hallucinogenic fish otoliths could be related to genetic predisposition as well as stress due to nutritional preference, pollutants, and environmental factors. RESEARCH HIGHLIGHTS: The presence of abnormalities in the otoliths of Sarpa salpa, a hallucinogenic fish, was revealed for the first time. Abnormalities in the otoliths of S. salpa were identified, such as the presence of various prominence structures on the otolith's surface, loss of parts as well as a more transparent appearance in the outlines or surface of the otolith. Normal and abnormal otoliths of female and male hallucinogenic fish from different size groups were examined using light and scanning electron microscopy. Abnormality detected in the otoliths of hallucinogenic fish is not related to the gender and size of the fish.

Using teacher-student neural networks based on knowledge distillation to detect anomalous samples in the otolith images

Otoliths are small calcium carbonate structures found in the inner ear of fish and they, as one of important information carriers, are applied in diverse ecological fields. Otoliths are usually photographed and used to explore many unsolved biological and ecological questions. However, many anomalies may occur in the large volume of otolith image data due to natural or artificial consequences, which brings a huge bias to the aimed study and even misleading results. In this study, we first propose a specific definition of otolith anomalies and provide a dataset of otolith anomalies with Electrona carlsbergi, one of the most abundant species of lanternfishes, as the study subject. We modify a multiresolution knowledge distillation neural network model, the state-of-the-art anomaly detection model to a multiresolution knowledge distillation network model with asymmetric inputs, which uses grayscale maps to align the features of color maps in the feature space, to help improve otolith anomalies detection. Our fine-tuned anomaly detection network obtains a better anomaly identification performance with a Receiving Operating Characteristic Area Under the Curve value of 0.9843. Our result shown that multiresolution knowledge distillation networks can efficiently identify abnormal otolith image sample, which is of great importance for conducting otolith-based science.

IK is essentially involved in ciliogenesis as an upstream regulator of oral-facial-digital syndrome ciliopathy gene, ofd1

BackgroundThe cilia are microtubule-based organelles that protrude from the cell surface. Abnormalities in cilia result in various ciliopathies, including polycystic kidney disease (PKD), Bardet-Biedl syndrome (BBS), and oral-facial-digital syndrome type I (OFD1), which show genetic defects associated with cilia formation. Although an increasing number of human diseases is attributed to ciliary defects, the functions or regulatory mechanisms of several ciliopathy genes remain unclear. Because multi ciliated cells (MCCs) are especially deep in vivo, studying ciliogenesis is challenging. Here, we demonstrate that ik is essential for ciliogenesis in vivo.ResultsIn the absence of ik, zebrafish embryos showed various ciliopathy phenotypes, such as body curvature, abnormal otoliths, and cyst formation in the kidney. RNA sequencing analysis revealed that ik positively regulated ofd1 expression required for cilium assembly. In fact, depletion of ik resulted in the downregulation of ofd1 expression with ciliary defects, and these ciliary defects in ik mutants were rescued by restoring ofd1 expression. Interestingly, ik affected ciliogenesis particularly in the proximal tubule but not in the distal tubule in the kidney.ConclusionsThis study demonstrates the role of ik in ciliogenesis in vivo for the first time. Loss of ik in zebrafish embryos displays various ciliopathy phenotypes with abnormal ciliary morphology in ciliary tissues. Our findings on the ik–ofd1 axis provide new insights into the biological function of ik in clinical ciliopathy studies in humans.

Expert consensus on the diagnosis of isolated otolith dysfunction

Isolated otolith dysfunction(iOD) involves a group of unexplained vestibular syndromes that manifest clinically as a sense of translation, tilting or floating, and blurred vision with head movement, with normal semicircular canal function but abnormal otolith function on laboratory vestibular testing. As vestibular medicine has gained widespread popularity in recent years, increasing attention has also been paid to iOD and case reports, clinical studies and diagnostic criteria have been published. However, there is no consensus document to guide the diagnosis of this disease in China. In this context, the Special Committee on Vertigo of China Medical Education Association organized a group of domestic experts in vestibular medicine and formulated this diagnostic consensus after thorough discussion based on the latest evidence in China and abroad, in order to promote the best clinical practice for iOD.

Morphological and morphometric features of the abnormal and normal saccular otoliths in flatfishes.

The fish's inner ear consists of three interconnected semicircular canals and otolith organs located in these canals, which are responsible for balance and hearing. Abnormalities in these organs can affect the vital activities of the fish. The main purpose of this study was to determine the morphological and morphometric characteristics of abnormal and normal sagittal otoliths in the four flatfish species (Lepidorhombus boscii, Platichthys flesus, Solea solea, and Pegusa lascaris) sampled from three seas (Aegean Sea, Mediterranean Sea, and Black Sea). Abnormalities in otoliths are investigated using light microscopy, scanning electron microscopy, and Raman spectroscopy. The otolith morphometric measurements and morphology are recorded for abnormal and normal otoliths for each species. It was determined that the four flatfish species examined in the present study showed differences in the morphological features of normal and abnormal otoliths in the blind and eyed sides. In addition, statistical differences were observed when the weight, length, width, perimeter, and area values of normal and abnormal otoliths of all species were compared (p < .05). The four types of saccular otoliths were defined, one normal (type 0) and three abnormal (type 1, type 2, and type 4) for four flatfish species. The current study presents for the first-time abnormal otolith morphology information on blind and eyed side sagittal otoliths in these flatfish species. Abnormalities in the anatomical structures of bony parts such as otoliths in fish may be caused by pollution, nutritional problems, stress, and environmental factors as well as a combination of these.

First record of Abnormal Otoliths in the Greater Weever Trachinus draco (Trachinidae) in the Black Sea

First record of Abnormal Otoliths in the Greater Weever Trachinus draco (Trachinidae) in the Black Sea

ALKBH3-dependent m1A demethylation of Aurora A mRNA inhibits ciliogenesis

Primary cilia are antenna-like subcellular structures to act as signaling platforms to regulate many cellular processes and embryonic development. m1A RNA modification plays key roles in RNA metabolism and gene expression; however, the physiological function of m1A modification remains largely unknown. Here we find that the m1A demethylase ALKBH3 significantly inhibits ciliogenesis in mammalian cells by its demethylation activity. Mechanistically, ALKBH3 removes m1A sites on mRNA of Aurora A, a master suppressor of ciliogenesis. Depletion of ALKBH3 enhances Aurora A mRNA decay and inhibits its translation. Moreover, alkbh3 morphants exhibit ciliary defects, including curved body, pericardial edema, abnormal otoliths, and dilation in pronephric ducts in zebrafish embryos, which are significantly rescued by wild-type alkbh3, but not by its catalytically inactive mutant. The ciliary defects caused by ALKBH3 depletion in both vertebrate cells and embryos are also significantly reversed by ectopic expression of Aurora A mRNA. Together, our data indicate that ALKBH3-dependent m1A demethylation has a crucial role in the regulation of Aurora A mRNA, which is essential for ciliogenesis and cilia-associated developmental events in vertebrates.

Vestibular evoked myogenic potentials in chronic renal disease

Background There is limited evidence to provide an insight on the VEMP characteristics to explain the association between chronic renal disease (CRD) and its effect on otolith structures. Objective To compare the otolithic function of individuals with CRD and individuals with no known CRD. To investigate the relationship between disease duration and VEMP and creatine level and VEMP among individuals with CRD. Method A cross-sectional study design using convenient sampling method was adapted for the present study. A total of 50 adults aged between 40 and 60 years participated in the study. Group 1 included 25 individuals with CRD undergoing hemodialysis and Group 2 included 25 individuals with no known CRD. cVEMP and oVEMP were recorded from participants in both groups. Results cVEMP and oVEMP was absent in 28% and 44% of individuals with CRD respectively, while, both VEMPs were present among all participants in group 2. Further, peak-to-peak amplitude of VEMP was reduced in individuals with CRD suggesting abnormal otolith function. In addition, a negative correlation was found between disease duration and the peak-to-peak amplitude of VEMP. Conclusion The abnormal VEMP findings in individuals with CRD shows presence of otolithic dysfunction along with amplitude is found to decrease with an increase in the disease duration.

Frequency of vateritic otoliths and potential consequences for marine survival in hatchery-reared Atlantic salmon.

Otoliths are inner-ear structures of all teleost fish with functional importance for hearing and balance. The otoliths usually consist of aragonite, a polymorph of calcium carbonate, but may also take the form partly or entirely of vaterite, a different polymorph of calcium carbonate. Vateritic otoliths occur sporadically in wild fish, but with a higher frequency in hatchery-reared fish. Abnormal otoliths have direct consequences for the inner-ear functions of fish and may be a symptom of environmental stress. In this study, the authors assess the differences in the frequency of abnormal otoliths and degree of abnormality (% vaterite) for different groups of hatchery-reared Atlantic salmon (Salmo salar) smolt and adults. The groups differed in parental broodstock origin (number of generations in hatchery) and treatment temperature. Smolt from the same groups were also released to complete their ocean migration. The otoliths of the returning and recaptured adults were subsequently extracted to assess the difference in frequency and degree of abnormality between the adults and the smolt from corresponding groups. Return rate varied among groups (0.2%-2.6%). The frequency of vateritic otoliths was high (11.4%-64.4%) and differed among smolt groups. The lowest return rates corresponded with the highest frequency of abnormal otoliths for the groups, suggesting that abnormal otoliths may have negative consequences for marine survival. Furthermore, indications of an effect of fast growth on the formation of abnormal otoliths were found for only one of the experimental groups, and for none of the groups after correcting for Type 1 error. This contradicts previous reports, suggesting rapid growth as the main cause of abnormal otoliths. Adult return rates were generally low, but abnormal otoliths were common, with high coverage (% vaterite).

Zebrafish stm is involved in the development of otoliths and of the fertilization envelope.

SummaryUsing an in vivo assay, we selected 11 genes that were highly upregulated during the induction of ovulation in zebrafish using microarray analysis and RNA sequencing. The starmaker gene (stm) was one of these genes. Although stm has been previously reported to be involved in otolith formation during the early development of zebrafish, we detected its expression in eggs and showed that stm was related to fertilization by establishing an stm gene knockout strain using the CRISPR/Cas9 system. Further phenotypic analysis of stm knockout fish was conducted in this study. With a higher nonfertilization rate, the stm mutant strain showed an extremely low survival rate. Otoliths of stm homozygous mutant zebrafish showed abnormal morphology in embryos and adult fish. However, fish did not show any abnormalities in swimming behaviour in either embryos or adults. Stm proteins were detected on the chorion of ovulated eggs before spawning. Fibre-supported knob-like structures on the fertilization envelope (FE) also showed abnormal structures in stm mutants. The Stm protein is necessary for otolith formation, and a lack of Stm causes abnormal otolith formation. The partial defect of otolith formation does not cause defects in swimming behaviour. The Stm protein is expressed in the chorion and is responsible for the formation of fibre-supported knob-like structures on the FE. It was suggested that a lack of Stm caused a lower fertilization rate due to inadequate formation of the FE.Lay summaryIn zebrafish, the protein Starmaker (Stm) was identified as having a role in ovulation. Stm is also known to be required for the formation of ear stones (otoliths) which are needed to keep the body in balance. Zebrafish lacking Stm were produced by genome editing. As expected, Stm-deficient fish formed abnormal otoliths. To investigate the role of Stm in ovulation, fertilization and early development, we tried mating of Stm mutants and observed their juveniles. Although no problem found in ovulation, we found low fertilization rate and abnormal structure of knob-like structure (small pit) on the egg membrane. Survival rate of embryos with abnormal egg membrane was extremely low. It was demonstrated that Stm protein is necessary to form the functional egg membrane to protect embryos from the outside environment.

Aberrant otoliths in four marine fishes from the Aegean Sea, Black Sea, and Sea of Marmara (Turkey)

Saccular otoliths are hearing and balance structures in teleosts and normally consist of aragonite, but in some cases may become aberrant vaterite. Environmental factors, nutritional problems, pollution, stress, and changes in water parameters, as well as a combination of these, may cause abnormal saccular otoliths. The aberrant otoliths may cause several problems such as discriminating hyaline and opaque rings, validating and tracing otolith rings, and measuring radii in the fisheries studies. In the present study, the aberrant and normal saccular otoliths morphologies were examined and described in Pagellus acarne, Trachurus mediterraneus, Diplodus puntazzo, and Merlangius merlangus from the Aegean Sea, Black Sea, and Sea of Marmara. The saccular otolith morphologies of the four fish species were classified from normal to completely crystalline as ”Type 0”, ”Type 1”, ”Type 2”, ”Type 4”, and ”Type 5”. ”Type 3” was not detected in the current study. The current study presents for the first time anomalous otolith morphology on the saccular otoliths in the D puntazzo, P. acarne, and T. mediterraneus. The data obtained from this study provide a comparison between populations and habitats for the researchers working in this field. The present study revealed that different fish species represented distinctive and similar morphological otolith characteristics in terms of abnormal otolith morphology.

Proposal on the Diagnostic Criteria of Definite Isolated Otolith Dysfunction.

Background and ObjectivesDizzy patients with abnormal otolith function tests, despite a normal caloric response, are defined as having specific (isolated) otolith organ dysfunction. This study was performed to compare the differences in clinical presentation between isolated otolith dysfunction (iOD) patients with lab- and Sx-based iOD group and lab-based iOD symptoms.Subjects and MethodsThe medical records of 23 iOD patients with normal caloric response but abnormal cervical vestibular evoked myogenic potential (VEMP), ocular VEMP, or subjective visual vertical were reviewed. Non-spinning vertigo was considered as otolith-related symptoms. The patients’ age, onset of dizziness, Numeric Rating Scale on the severity of dizziness, and concomitant vestibular disorders were analyzed.ResultsPatients in the lab-based iOD group were significantly older than those in the lab- and Sx-based iOD group. Known vestibular disorders were significantly more common in the lab-based iOD group (83.3%) compared to the lab- and Sx-based iOD group (18.2%). Despite the normal caloric response, catch-up saccade was found in the video head impulse test in more than half (54.5%) of the lab-based iOD group patients. There was no catch-up saccade in the lab- and Sx-based iOD group. There were no significant differences in gender ratio, frequency of dizziness attacks, and duration of illness.ConclusionsWe propose new definitions of definite iOD (lab- and Sx-based iOD) and probable iOD (lab- or Sx-based iOD). These new definitions may help researchers to identify patients who are more likely to have true iOD, and facilitate comparisons of results between different studies.

Vertebrate Dynein-f depends on Wdr78 for axonemal localization and is essential for ciliary beat.

Motile cilia and flagella are microtubule-based organelles important for cell locomotion and extracellular liquid flow through beating. Although axonenal dyneins that drive ciliary beat have been extensively studied in unicellular Chlamydomonas, to what extent such knowledge can be applied to vertebrate is poorly known. In Chlamydomonas, Dynein-f controls flagellar waveforms but is dispensable for beating. The flagellar assembly of its heavy chains (HCs) requires its intermediate chain (IC) IC140 but not IC138. Here we show that, unlike its Chlamydomonas counterpart, vertebrate Dynein-f is essential for ciliary beat. We confirmed that Wdr78 is the vertebrate orthologue of IC138. Wdr78 associated with Dynein-f subunits such as Dnah2 (a HC) and Wdr63 (IC140 orthologue). It was expressed as a motile cilium-specific protein in mammalian cells. Depletion of Wdr78 or Dnah2 by RNAi paralyzed mouse ependymal cilia. Zebrafish Wdr78 morphants displayed ciliopathy-related phenotypes, such as curved bodies, hydrocephalus, abnormal otolith, randomized left–right asymmetry, and pronephric cysts, accompanied with paralyzed pronephric cilia. Furthermore, all the HCs and ICs of Dynein-f failed to localize in the Wdr78-depleted mouse ependymal cilia. Therefore, both the functions and subunit dependency of Dynein-f are altered in evolution, probably to comply with ciliary roles in higher organisms.

Abnormal otoliths in the marine fishes collected from the Persian Gulf and the Gulf of Oman

Background. Although several researchers have examined otoliths of marine fishes from the Persian Gulf and the Gulf of Oman, none has reported abnormalities. A recent effort to identify stocks of marine fishes of the Persian Gulf and the Gulf of Oman revealed that several species have abnormal otoliths. This is the first study reporting and describing the occurrence of abnormal otoliths from the fishes collected from the Persian Gulf and the Gulf of Oman. Materials and methods. A total of 225 fish specimens belong to 83 species and 33 families were randomly sampled from the Persian Gulf and the Gulf of Oman. The standard lengths (SL) were measured to the nearest 0.5 mm. The otoliths were extracted, cleaned, and described following available literature. The specimens and their otoliths were deposited in the Zoological Museum at Shahid Bahonar University of Kerman (ZM-SBUK). Results. Among the studied 83 species, we found six species having abnormal otoliths (4.8% of the studied specimens). They belong to six families; Carangidae, Chanidae, Chirocentridae, Leiognathidae, Paralichthyidae, and Sparidae. The number of specimens with abnormal otoliths only in one side (either right or left side) was six, and those with abnormal otoliths in both sides was five. The left otoliths presented more extreme changes than the right. The observed abnormalities can be classified into three types; asteriscus attached to sagittal (the most common); otoliths with a more translucent or crystalline appearance in surface or outlines; and those with an abnormality in their sulcus region. Conclusion. Ecologically, the Persian Gulf is an environment having various kinds of stresses such as salinity fluctuation, acidification, and the water temperature. Such stressors probably affect otolith formation during the larval stages of these fishes and are responsible for the observed abnormalities.

MicroRNA-194 Regulates the Development and Differentiation of Sensory Patches and Statoacoustic Ganglion of Inner Ear by Fgf4.

BackgroundMicroRNA 194 is involved in the differentiation of various types of cells, such as adipose derived stem cells, human embryonic stem cells, and bone marrow mesenchymal stem cells. Previously, we found that miR-194 was highly expressed in the inner ear sensory patch and neurons in mice embryos. However, the role of miR-194 in the development of the inner ear and its underlying mechanism have not been elucidated yet.Material/MethodsThe expression level of miR-194 has been altered by using antisense morpholino oligonucleotides (MO) and synthesized miRNAs in zebrafish.ResultsWe found that miR-194 was vastly expressed in the inner ear and central nervous system (CNS) in zebrafish. Loss of function of miR-194 could strongly affected the development of zebrafish embryos, including delayed embryonic development, edema of the pericardium, small head, axial deviation, delayed development of inner ear, closer location of two otoliths, delayed fusion of the semicircular canals, and abnormal otolith number in some cases. In addition, the behavior of zebrafish was also adversely affected with impaired balance and biased swimming route. Misexpression of miR-194 could strongly affected the development and differentiation of spiral ganglion neuron (SGN) in inner ear through Fgf4 in vitro. Similar results have also been observed that the overexpression and knockdown of miR-194 strongly disturbed the development and differentiation of the sensory patches and Statoacoustic ganglion (SAG) through Fgf4 in zebrafish in vivo. Our results indicated that miR-194 may regulate the development and differentiation of sensory patches and SAG through Fgf4.ConclusionsOur data revealed a vital role of miR-194 in regulating the development and differentiation of the inner ear.

High incidence of otolith abnormality in juvenile European flounder Platichthys flesus from a tidal freshwater area

ABSTRACTOtolith abnormality has been reported for a wide range of freshwater and marine fish species. In this study, the sagittal otolith morphology and mineralogy of juvenile European flounder, Platichthys flesus, were examined to describe the incidence and types of structural deformities in this species. Juvenile flounder were collected over the years 2013–2015 in the tidal freshwater section of an estuarine nursery (Minho estuary, NW Portugal). Otolith abnormality was found in 43% of the individuals and, in most cases, occurred in both otoliths. Despite an abnormal mineralogy confirmed by scanning electron microscopy, the morphometry and the mineral polymorph composition of abnormal otoliths did not differ from normal ones (i.e. aragonite). This contrasts with other studies where vaterite and/or calcite were found to replace aragonite in abnormal otoliths. Further studies are needed to elucidate whether abrupt salinity changes associated with habitat transitions may have played a role in the abnormal otolith biomineralization in this species.

Vitamin D receptor deficiency impairs inner ear development in zebrafish

The biological actions of vitamin D are largely mediated through binding to the vitamin D receptor (VDR), a member of the nuclear hormone receptor family, which regulates gene expression in a wide variety of tissues and cells. Mutations in VDR gene have been implicated in ear disorders (hearing loss and balance disorder) but the mechanisms are not well established. In this study, to investigate the role of VDR in inner ear development, morpholino-mediated gene knockdown approaches were used in zebrafish model system. Two paralogs for VDR, vdra and vdrb, have been identified in zebrafish. Knockdown of vdra had no effect on ear development, whereas knockdown of vdrb displayed morphological ear defects including smaller otic vesicles with malformed semicircular canals and abnormal otoliths. Loss-of-vdrb resulted in down-regulation of pre-otic markers, pax8 and pax2a, indicating impairment of otic induction. Furthermore, zebrafish embryos lacking vdrb produced fewer sensory hair cells in the ears and showed disruption of balance and motor coordination. These data reveal that VDR signaling plays an important role in ear development.