Cuticular Plate Research Articles

Proprioceptors involved in stinging response of the honeybee, Apis mellifera

Two types of mechanosensitive proprioceptor organ are present on the stinging apparatus of the honeybee: campaniform sensilla and mechanosensory hairplates. The campaniform sensilla are located on the surface of the tapering sting-shaft, which comprises an unpaired stylet and paired lancets. Each sensillum on the lancet differs from that on the stylet in terms of their topography and external morphology. The sensory afferents of the campaniform sensilla display slow-adapted firing responses to deformation of the cuticle that would be caused by the action of inserting the sting into a substrate, and their afferent signals induce and/or prolong the stinging response. By contrast, the mechanosensory hairplates are located at basal cuticular plates and on the posterior surface of the lancet valves. Two fields of hairplates on the second ramus at the ventral edge of the groove and on the antero-lateral edge of the oblong plate respond synchronously to protraction of the lancet. During the stinging response, these hairplates are likely to detect any sliding movement of the lancet and its position relative to the stylet. Afferent signals produced by them are likely to provide important information to the neuronal circuit for the generation and modulation of the stinging motor pattern.

α‐II‐spectrin as a marker for the striated organelle in inner ear hair cells

Located in the subcuticular zone of vestibular and auditory hair cells, the striated organelle's form, occurrence and function remain largely unknown. Studying its architecture by employing serial section transmission electron microscopy, intermediate voltage electron microscopy and electron microscope tomography, we have come to recognize that the striated organelle (SO) is a cytoskeletal apparatus shaped like an inverted cone that is made up of alternating thin and thick filaments. It is associated with microtubules, endoplasmic reticular and large mitochondria that have polarized, lamellar cristae. It is attached to both stereociliar rootlets and the cell membrane, raising the prospect of an active role in hair cell mechanotransduction. As we attempt to answer questions pertaining to its function, unraveling its protein composition is essential. In this study we examined the development of α‐II‐spectrin immunoreactivity in rats (aged P1 to adult). Our confocal data show cuticular plate labeling in both type I and II hair cells in the cristas, utricules and saccules. More telling is the localization of α‐II‐spectrin in the region where the SO occurs. The staining pattern here is less intense in younger animals and more pronounced in the adult.Grant Funding Source: NIH R01‐DC02521

Analysis of subcellular localization of Myo7a, Pcdh15 and Sans in Ush1c knockout mice

Usher syndrome (USH) is the most frequent cause of combined deaf-blindness in man. An important finding from mouse models and molecular studies is that the USH proteins are integrated into a protein network that regulates inner ear morphogenesis. To understand further the function of harmonin in the pathogenesis of USH1, we have generated a targeted null mutation Ush1c mouse model. Here, we examine the effects of null mutation of the Ush1c gene on subcellular localization of Myo7a, Pcdh15 and Sans in the inner ear. Morphology and proteins distributions were analysed in cochlear sections and whole mount preparations from Ush1c(-/-) and Ush1c(-/+) controls mice. We observed the same distribution of Myo7a throughout the cytoplasm in knockout and control mice. However, we detected Pcdh15 at the base of stereocilia and in the cuticular plate in cochlear hair cells from Ush1c(+/-) controls, whereas in the knockout Ush1c(-/-) mice, Pcdh15 staining was concentrated in the apical region of the outer hair cells and no defined staining was detected at the base of stereocilia nor in the cuticular plate. We showed localization of Sans in the stereocilia of controls mouse cochlear hair cells. However, in cochleae from Ush1c(-/-) mice, strong Sans signals were detected towards the base of stereocilia close to their insertion point into the cuticular plate. Our data indicate that the disassembly of the USH1 network caused by absence of harmonin may have led to the mis-localization of the Protocadherin 15 and Sans proteins in the cochlear hair cells of Ush1c(-/-) knockout mice.

Supporting Cells Eliminate Dying Sensory Hair Cells to Maintain Epithelial Integrity in the Avian Inner Ear

Epithelial homeostasis is essential for sensory transduction in the auditory and vestibular organs of the inner ear, but how it is maintained during trauma is poorly understood. To examine potential repair mechanisms, we expressed β-actin-enhanced green fluorescent protein (EGFP) in the chick inner ear and used live-cell imaging to study how sensory epithelia responded during aminoglycoside-induced hair cell trauma. We found that glial-like supporting cells used two independent mechanisms to rapidly eliminate dying hair cells. Supporting cells assembled an actin cable at the luminal surface that extended around the pericuticular junction and constricted to excise the stereocilia bundle and cuticular plate from the hair cell soma. Hair bundle excision could occur within 3 min of actin-cable formation. After bundle excision, typically with a delay of up to 2-3 h, supporting cells engulfed and phagocytosed the remaining bundle-less hair cell. Dual-channel recordings with β-actin-EGFP and vital dyes revealed phagocytosis was concurrent with loss of hair cell integrity. We conclude that supporting cells repaired the epithelial barrier before hair cell plasmalemmal integrity was lost and that supporting cell activity was closely linked to hair cell death. Treatment with the Rho-kinase inhibitor Y-27632 did not prevent bundle excision but prolonged phagocytic engulfment and resulted in hair cell corpses accumulating within the epithelium. Our data show that supporting cells not only maintain epithelial integrity during trauma but suggest they may also be an integral part of the hair cell death process itself.

Comparative morphology and ultrastructure of the mouthparts in unfed larvae of Platytrombidium fasciatum and Camerotrombidium pexatum (Acariformes: Microtrombidiidae)

The mouthparts of unfed larvae of Platytrombidium fasciatum (C. L. Koch, 1836) and Camerotrombidium pexatum (C. L. Koch, 1837) (Acariformes: Microtrombidiidae) were studied using both light optical (whole-mounted specimens, toluidine blue stained semi-thin sections) and electron microscope (TEM, SEM) methods. The mouth apparatus incorporated within the gnathosoma occupies an axial position and is covered from above by the arched dorsal shield, or scutum. The chelicerae are comparatively long and separated, and the lateral lips form a permanent apomorphic sucker provided with an internal cuticular sclerite. The pharynx is extremely wide and totally fused with the bottom of the infracapitulum. The pharyngeal dilators originate on the posterior portions of the cervix (epistome) and on the capitular apodemes and run nearly parallel to the cervix to the dorsal pharyngeal wall. Comparatively short sigmoid pieces serve as origin of the muscles--cheliceral levators inserting on the posterior wall of the basal cheliceral segments. There are two sets of the extrinsic gnathosomal muscles originating on the posterior portion of the scutum: retractors of chelicerae inserting on the posterior portions of the basal cheliceral segments, and retractors of the gnathosoma inserting on the very posterior parts of the capitular apodemes. The labrum and the cervix delimit the pharynx and the subcheliceral space. The labrum and the cervix for the most part are weakly sclerotized cuticular plates and do not have own muscles. The larval mouth apparatus, in comparison with that of adult microtrombidiid mites, is simply organized and more specialized for ingestion of large masses of liquid food.

The erection of Pelecanema n. g. (Nematoda: Spirurida: Acuariidae), with redescriptions of P. sirry (Khalil, 1931) n. comb. and P. pelecani (Johnston & Mawson, 1942) n. comb.

Pelecanema n. g. is erected for P. sirry (Khalil, 1931) n. comb., syn. Synhimantus sirry Khalil, 1931 (type-species) and P. pelecani (Johnston & Mawson, 1942) n. comb., syn. Dispharynx pelecani Johnston & Mawson, 1942. In the structure of its cordons, consisting of two rows of delicate cuticular plates, the new genus is similar to Synhimantus Railliet, Henry & Sisoff, 1912, Dispharynx Railliet, Henry & Sisoff, 1912, Chordatortilis Machado de Mendonça & Olivera de Rodrigues, 1965 and Parachordatortilis Mutafchiev, Santoro & Georgiev, 2010. Pelecanema sirry, a parasite of Pelecanus onocrotalus L. and P. crispus Bruch (Pelecaniformes, Pelecanidae) in Africa (Egypt and Senegal) and Europe (Ukraine and Bulgaria), is redescribed using light and scanning electron microscopy on the basis of specimens from P. crispus from Bulgaria. Pelecanema pelecani, a parasite of Pelecanus conspicillatus Temminck in Australia, is also redescribed using light microscopy on the basis of specimens from its type-host and type-locality. In contrast to a previous opinion recognising Pelecanema sirry and P. pelecani as synonyms, the two species are considered distinct and P. pelecani is validated.

Parachordatortilis n. g. (Nematoda: Spirurida: Acuariidae), with a redescription of P. mathevossianae (Petrov & Chertkova, 1950) n. comb., a parasite of Falco tinnunculus L. (Aves: Falconiformes)

Parachordatortilis n. g. is proposed as a monotypic genus for Parachordatortilis mathevossianae (Petrov & Chertkova, 1950) n. comb. (Spirurida, Acuariidae), previously Dispharynx mathevossianae Petrov & Chertkova, 1950. The new genus can be distinguished from all other acuariid genera by having cordons with a sinistral torsion. Parachordatortilis possesses cordons consisting of two rows of delicate cuticular plates delimiting a longitudinal canal. This pattern of cordon structure suggests that Parachordatortilis is closely related to Dispharynx Railliet, Henry & Sisoff, 1912, Synhimantus Railliet, Henry & Sisoff, 1912 and Chordatortilis Machado de Mendonça & Olivera de Rodrigues, 1985. P. mathevossianae is redescribed on the basis of light and scanning electron microscopical observations of specimens collected from a common kestrel Falco tinnunculus L. in southern Italy.

Targeted Capture and Next-Generation Sequencing Identifies C9orf75, Encoding Taperin, as the Mutated Gene in Nonsyndromic Deafness DFNB79

Targeted genome capture combined with next-generation sequencing was used to analyze 2.9 Mb of the DFNB79 interval on chromosome 9q34.3, which includes 108 candidate genes. Genomic DNA from an affected member of a consanguineous family segregating recessive, nonsyndromic hearing loss was used to make a library of fragments covering the DFNB79 linkage interval defined by genetic analyses of four pedigrees. Homozygosity for eight previously unreported variants in transcribed sequences was detected by evaluating a library of 402,554 sequencing reads and was later confirmed by Sanger sequencing. Of these variants, six were determined to be polymorphisms in the Pakistani population, and one was in a noncoding gene that was subsequently excluded genetically from the DFNB79 linkage interval. The remaining variant was a nonsense mutation in a predicted gene, C9orf75, renamed TPRN. Evaluation of the other three DFNB79-linked families identified three additional frameshift mutations, for a total of four truncating alleles of this gene. Although TPRN is expressed in many tissues, immunolocalization of the protein product in the mouse cochlea shows prominent expression in the taper region of hair cell stereocilia. Consequently, we named the protein taperin.

Apodopsyllus gabesensis n. sp.: a new species of Paramesochridae (Copepoda: Harpacticoida) from the Gulf of Gabès (south-eastern Tunisia)

Several specimens belonging to a new species of Apodopsyllus were collected during a study on the diversity of meiobenthic communities in the Gulf of Gabes, a Mediterranean shallow-water bay at the south-eastern coast of Tunisia in July 2005. The new species Apodopsyllus gabesensis n. sp. shares the characteristics of the genus such as the lack of endopods from P2 to P4 and the soft and slightly cuticularized body. Apodopsyllus gabesensis n. sp. belongs to the few known species of Apodopsyllus that are described to have comparably distinct patterns of dorsal and lateral cuticular plates and pores. Besides a typical combination of characters that clearly distinguishes the new species from its congeners, the new species shows the following unique single characters: female P5 with a hitherto unknown combination of shape of the exopodal part and shape and setation of the baseoendopodal lobe with two small stout spines; male P6 with a particular shape, and a distinct armature of the exopodal spines in P2–P4 in the male that are pinnate with very short spinules contrary to the female where spines are smooth. The genus Apodopsyllus contains 26 species with the inclusion of the new species.

Mechanisms of rapid sensory hair-cell death following co-administration of gentamicin and ethacrynic acid

Concurrent administration of a high dose of gentamicin (GM; 125 mg/kg IM) and ethacrynic acid (EA; 40 mg/kg IV) results in rapid destruction of virtually all cochlear hair cells; however, the cell death signaling pathways underlying this rapid form of hair-cell degeneration are unclear. To elucidate the mechanisms underlying GM/EA-mediated cell death, several key cell death markers were assessed in the chinchilla cochlea during the early stages of degeneration. In the middle and basal turns of the cochlea, massive hair-cell loss including destruction of the stereocilia and cuticular plate occurred 12 h after GM/EA treatment. Condensation and fragmentation of outer hair-cell nuclei, morphological features of apoptosis, were first observed 5–6 h post-treatment in the basal turn of the cochlea. Metabolic function, reflected by succinate dehydrogenase histochemistry and mitochondrial staining, decreased significantly in the basal turn 4 h following GM/EA treatment; these early changes were accompanied by the release of cytochrome c from the mitochondria into the cytosol and intense expression of initiator caspase-9 and effector caspase-3. GM/EA failed to induce expression of extrinsic initiator caspase-8. These results suggest that the rapid loss of hair cells following GM/EA treatment involves cell death pathways mediated by mitochondrial dysfunction leading to the release of cytochrome c, activation of initiator caspase-9 and effector caspase-3.

Ultrastructure of the Hair in Genetic Prelingual Deafness Associated with the 35delG Mutation in the Connexin 26 Gene (GJB2)

Ultrastructure of the surface of long hair in 77 subjects with a phenotype of childhood prelingual deafness was evaluated by scanning electron microscopy. The subjects were homozygous or heterozygous carriers of the 35delG mutation in the connexin 26 gene (GJB2). The presence of severe abnormalities in the marginal layer of the cuticular plate (fracture-like defects) is pathognomonic for homozygous carriers of the 35delG mutation. Ultrastructural characteristics of the hair in subjects with connexin-associated deafness significantly differed from those in healthy volunteers (control group of the same age) and deaf people with non-genetic hearing impairment. Analysis of variance revealed no differences in hair thickness between deaf homozygous and heterozygous carriers of the 35delG GJB2 gene mutation and healthy volunteers.

Palaeoscolecid scleritome fragments withHadimopanellaplates from the early Cambrian of South Australia

AbstractPhosphatized articulated palaeoscolecid scleritome fragments with attachedHadimopanellaGedik, 1977 plates are described from the lower Cambrian Mernmerna Formation of South Australia.Hadimopanellais principally known from single, isolated, button-shaped, phosphatic sclerites. The new articulated material from South Australia reveals for the first time the configuration of plates referable toHadimopanellawithin the scleritome. The scleritome fragments represent the main trunk sections of the cuticle with anterior and posterior terminations lacking. Each annulus on the trunk is ornamented by rows of irregularly alternatingHadimopanellaplates. The large majority of plates display a single, centrally located, conical node referable to the form speciesH. apicataWrona, 1982. However, individual plates display considerable morphological variation with plates situated along the flattened trunk margin identical to the form speciesH. antarcticaWrona, 1987. The South Australian material displays the detailed scleritome configuration of cuticular plates and platelets and demonstrates irrefutably that plates of the form speciesH. apicataandH. antarcticaoccur as mineralized cuticular elements on the same palaeoscolecid scleritome.

Analysis of Cochlear Protein Profiles of Wistar, Sprague−Dawley, and Fischer 344 Rats with Normal Hearing Function

Differences in the expression of cochlear proteins are likely to affect the susceptibility of different animal models to specific types of auditory pathology. However, little is currently known about proteins that are abundantly expressed in inner ear. Identification of these proteins may facilitate the search for biomarkers of susceptibility and intervention targets. To begin to address this issue, we analyzed cochlear protein profiles of three strains of rats, Wistar, Sprague-Dawley, and Fischer 344, using a broad spectrum antibody microarray. Normal hearing function of the animals was ascertained using distortion product otoacoustic emissions (DPOAE). Of 725 proteins screened in whole cochlea, more than 80% were detected in all three strains. However, there were striking differences in the levels at which they occur. Among 213 proteins expressed at levels>or=2 fold of actin, only 7.5% were detected at these levels in all three strains. Myosin light chain kinase (MLCK) was immunolocalized in cuticular plate of outer hair cells (OHC) while mitogen activated protein (MAP) kinase-extracellular-signal regulated kinase1/2 (ERK1/2) was detected as foci in OHC, pillar cells, strial marginal cells, and fibroblasts of spiral ligament. A review of literature indicated that the expression of 7 (44%) of these 16 proteins were detected for the first time in the inner ear, although there were implications of the presence of some of these proteins. One of these abundant, but unstudied, proteins, MAP kinase activated protein kinase2 (MAPKAPK2), shows strong immunolabeling in pillar cells and inner hair cells (IHC). There was moderate MAPKAPK2 labeling in OHC, supporting cells, neurons, and marginal, intermediate, and basal cells. The current study provides the first, large cochlear protein profile of multiple rat strains. The diversity in expression of abundant proteins in these strains may contribute to differences in susceptibility of these strains to aging, noise, or ototoxic drugs.

Redescription of Desportesius brevicaudatus (Spirurida, Acuariidae) based on nematodes from Ixobrychus minutus (Aves, Ciconiiformes) from Bulgaria

Abstract Desportesius brevicaudatus (Dujardin, 1845) is redescribed on the basis of light-microscopy and SEM observations on specimens collected from the oesophagus and under the lining of the gizzard of Ixobrychus minutus (Ardeidae) from Bulgaria. New metrical data expand the known ranges of variation of the measurements of the body, tail, cordons, oesophagus and spicules. New information is provided on the variation of the shape of the deirids, the structure of the vagina, the complexity of the cordons, the pattern of the cuticular striation and the shape of the postdeirids. Cordons are described as consisting of a single row of serrate cuticular plates and a longitudinal cuticular ridge along the outer rims of the cuticular plates. The cuticular ridge is interpreted as homologous to the outer row of plates in the cordons of the genera Acuaria, Cheilospirura and Echinuria.

Streptomycin-induced apoptosis of rat cochlear hair cell cultured in vitro

To evaluate if caspase pathway was involved in streptomycin-induced cell apoptosis in cochlear hair cells. F344 rats at postnatal day 3 or 4 were used for the study in cochlear organotypic cultures. The cochlear basilar membrane was micro-dissected out and cultured overnight, and then treated with 1 mmol/L streptomycin for 24 hours. Before the termination, the activity of caspase-8, 9 or 6 were detected with FAM-peptide-FMK labeled caspase-8, 9 or 6, respectively. The stereocilia and cuticular plate of hair cells were stained with TRITC conjugated phalloidin, and the nuclei were stained with Topro-3 DNA probe. The specimens were observed and photographed under confocal fluorescent microscope. Streptomycin with 1 mmol/L causes about 80% cochlear hair cells missing in the basal turn and 10% hair cell loss in the apex. After streptomycin treatment, the nuclear shrinkage and fragmentation were found in most cochlear hair cells, and the caspase-8, caspase-9 and caspase-6 were greatly activated. Apoptosis is involved in the cochlear hair cells death induced by Streptomycin in vitro. The caspase activities in upstream and downstream are maybe the major apoptotic pathway.

A re‐examination of the striated organelle in vestibular endorgans

The striated organelle (STO) is a structure located in the subcuticular region of hair cells, consisting of alternating thick and thin bands. Although present in all cochlear and vestibular hair cells, the STO is particularly well‐developed in type I hair cells, where it is shaped like an inverted open ended cone that contacts the cell membrane along its entire circumference and is separated from the cuticular plate by a layer of mitochondria. In other hair cells, it is a much smaller structure and appears to be free‐floating. We studied its structure in EM tomography of the type I hair cell. In three‐dimensional reconstructions, we found that it is connected to at least some actin rootlets. It may also be associated with microtubules, mitochondria and smooth ER. Confocal immunohistochemistry places Yotiao (an AKAP protein) in the same area as the STO and the actin‐binding protein, alpha fodrin (non‐erythroid spectrin), where the STO contacts the cell membrane. The contact with the rootlets suggests that the STO might regulate hair‐bundle stiffness. Its association with the cell membrane suggests that the STO may help in the formation of the constricted neck characteristic of type I hair cells.Supported by NIH DC‐02521 and the 2008 Tallu Rosen Grant in Auditory Science (from the National Organization for Hearing Research Foundation)Grant Funding SourceNIH DC‐02521; 2008 Tallu Rosen Grant in Auditory Science (NOHR)

Cell proliferation follows acoustically-induced hair cell bundle loss in the zebrafish saccule

Fishes are capable of regenerating sensory hair cells in the inner ear after acoustic trauma. However, a time course of auditory hair cell regeneration has not been established for zebrafish. Adult zebrafish ( Danio rerio) were exposed to a 100 Hz pure tone at 179 dB re 1 μPa RMS for 36 h and then allowed to recover for 0–14 days before morphological analysis. Hair cell bundle loss and recovery were determined using phalloidin to visualize hair bundles. Cell proliferation was quantified through bromodeoxyuridine (BrdU) labeling. Immediately following sound exposure, zebrafish saccules exhibited significant hair bundle damage (e.g., splayed, broken, and missing stereocilia) and loss (i.e., missing bundles and lesions in the epithelia) in the caudal region. Hair bundle counts increased over the course of the experiment, reaching pre-treatment levels at 14 days post-sound exposure (dpse). Low levels of proliferation were observed in untreated controls, indicating that some cells of the zebrafish saccule are mitotically active in the absence of a damaging event. In sound-exposed fish, cell proliferation peaked two dpse in the caudal region, and to a lesser extent in the rostral region. This proliferation was followed by an increase in numbers of cuticular plates with rudimentary stereocilia and immature-like hair bundles at 7 and 14 dpse, suggesting that at least some of the saccular cell proliferation resulted in newly formed hair cells. This study establishes a time course of hair cell bundle regeneration in the zebrafish inner ear and demonstrates that cell proliferation is associated with the regenerative process.

The Striated Organelle: A Molecular Motor In Vestibular Type I Hair Cells

The striated organelle (STO) is a structure located in the subcuticular region of hair cells, consisting of alternating thick and thin bands (Friedman, 1965; Ross and Bourne, 1983). Although present in all cochlear and vestibular hair cells, the STO is particularly well-developed in type I hair cells, where it is shaped like an inverted open cone that contacts the cell membrane along its entire circumference. It is separated from the cuticular plate by a layer of mitochondria. In other hair cells, it is a much smaller structure and appears to be free-floating. We studied its structure using electron microscopic (EM) tomography in type I hair cells. In three-dimensional reconstructions, we found that it is connected to at least some actin rootlets. It may also be associated with microtubules, mitochondria and smooth endoplasmic reticulum. Confocal immunohistochemistry places yotiao (an AKAP protein) in the same area as the STO, and the actin-binding protein, alpha-fodrin (non-erythroid spectrin), where the STO contacts the cell membrane. The contact with the rootlets suggests that the STO might regulate hair-bundle stiffness. Its association with the cell membrane suggests that the STO may help in the formation of the constricted neck characteristic of type I hair cells.Supported by NIH DC-02521 and the 2008 Tallu Rosen Grant in Auditory Science from the National Organization for Hearing Research Foundation.

Distribution of Prestin on Outer Hair Cell Basolateral Surface

Prestin has been identified as a motor protein responsible for outer hair cell (OHC) electromotility and is expressed on the OHC surface. Previous studies revealed that OHC electromotility and its associated nonlinear capacitance were mainly located at the OHC lateral wall and absent at the apical cuticular plate and the basal nucleus region. Immunofluorescent staining for prestin also failed to demonstrate prestin expression at the OHC basal ends in whole–mount preparation of the organ of Corti. However, there lacks a definitive demonstration of the pattern of prestin distribution. The OHC lateral wall has a trilaminate organization and is composed of the plasma membrane, cortical lattice, and subsurface cisternae. In this study, the location of prestin proteins in dissociated OHCs was examined using immunofluorescent staining and confocal microscopy. We found that prestin was uniformly expressed on the basolateral surface, including the basal pole. No staining was seen on the cuticular plate and stereocilia. When co–stained with a membrane marker di–8–ANEPPS, prestin–labeling was found to be in the outer layer of the OHC lateral wall. After separating the plasma membrane from the underlying subsurface cisternae using a hypotonic extracellular solution, prestin–labeling was found to be in the plasma membrane, not the subsurface cisternae. The data show that prestin is expressed in the plasma membrane on the entire OHC basolateral surface.

αII-βV spectrin bridges the plasma membrane and cortical lattice in the lateral wall of the auditory outer hair cells

The sensitivity and frequency selectivity of the mammalian cochlea involves a mechanical amplification process called electromotility, which requires prestin-dependent length changes of the outer hair cell (OHC) lateral wall in response to changes in membrane electric potential. The cortical lattice, the highly organized cytoskeleton underlying the OHC lateral plasma membrane, is made up of F-actin and spectrin. Here, we show that alphaII and two of the five beta-spectrin subunits, betaII and betaV, are present in OHCs. betaII spectrin is restricted to the cuticular plate, a dense apical network of actin filaments, whereas betaV spectrin is concentrated at the cortical lattice. Moreover, we show that alphaII-betaV spectrin directly interacts with F-actin and band 4.1, two components of the OHC cortical lattice. betaV spectrin is progressively recruited into the cortical lattice between postnatal day 2 (P2) and P10 in the mouse, in parallel with prestin membrane insertion, which itself parallels the maturation of cell electromotility. Although betaV spectrin does not directly interact with prestin, we found that addition of lysates derived from mature auditory organs, but not from the brain or liver, enables betaV spectrin-prestin interaction. Using this assay, betaV spectrin, via its PH domain, indirectly interacts with the C-terminal cytodomain of prestin. We conclude that the cortical network involved in the sound-induced electromotility of OHCs contains alphaII-betaV spectrin, and not the conventional alphaII-betaII spectrin.