The polarisation of hair cells from the ear of the European bass (Dicentrarchus labrax)

The polarisation of ciliary bundles on the macula of the saccule in the European bass (Dicentrarchus labrax L) has been studied using a scanning electron microscope (SEM). These data show that D. labrax possesses ciliary bundles arranged in four dichotomous quadrants with a standard orientation, comparable to hearing generalists from the order Perciformes. The spacing between ciliary bundles was investigated in three size classes of fish, with the results indicating that the addition of receptor cells in the ear of D. labrax continues for at least the first 2 years of development. The lengths of the kinocilia from ciliary bundles in each quadrant of the macula were also studied, and found to be of uniform length. In addition, we look at the internal structure of the afferent using transmission electron microscopy (TEM), revealing the nucleated cell body and peripheral nerve fibres of the saccule consistent with other TEM examinations of saccular ultrastructure. This information is required to gain an insight into the inner ear of D. labrax, as part of a larger study of the morphology and physiology of the hearing systems of both vertebrate and invertebrate marine animals.     

Gross and ultrastructural development of the saccule of the toadfish Opsanus tau

The development of the saccule of the inner ear in the toadfish was studied using light and scanning electron microscopy. Development was studied from the early embryo (2-3 days postfertilization), when the otocyst first forms, to the early-aged juvenile when the development of the inner ear approximates that of the adult (4 weeks postfertilization). The ultrastructural features examined included the morphological sequence of ciliary bundle growth, the development of orientation patterns of the ciliary bundles, and the relation of the ultrastructural development to overall gross development. Gross development may be divided into four distinct morphological stages. Stage I encompasses the time from initial formation of the otocyst until the start of stage II, which is the stage when the pars inferior begins migrating ventrally. In stage III the pars inferior continues to elongate ventrally. Stage IV starts when the pars inferior elongates in a rostral and caudal direction. The ear attains its adult shape in stage IV. The differentiation of the sensory cells begins during stage I. During the early part of stage I, a small cilium is found on the apical surface of each cell throughout the otocyst. In the middle and late periods of stage I, a few microvillous buds add to the surface of the cells that already have a kinocilium. These early ciliary bundles are clustered on the rostral-ventral and caudal walls of the otocyst. There is no clear patterning to the orientation of these ciliary bundles. In stage II the ventral stretching of the labyrinth wall causes a spreading of the clustered bundles along the ventral and medial walls of the pars inferior. The orientation of the ciliary bundles has no distinct pattern. In stage III the orientations of the ciliary bundles appear adultlike, although there are so few ciliary bundles that it is difficult to make a definite determination. During stage IV, hair cells with an adultlike horizontal and vertical orientation pattern are found on the rostral and caudal sections of the saccular macula, respectively. The transition region lying between these areas has ciliary bundles with various orientations.     

Wnt signaling mediates reorientation of outer hair cell stereociliary bundles in the mammalian cochlea

In the mammalian cochlea, stereociliary bundles located on mechanosensory hair cells within the sensory epithelium are unidirectionally oriented. Development of this planar polarity is necessary for normal hearing as stereociliary bundles are only sensitive to vibrations in a single plane; however, the mechanisms governing their orientation are unknown. We report that Wnt signaling regulates the development of unidirectional stereociliary bundle orientation. In vitro application of Wnt7a protein or inhibitors of Wnt signaling, secreted Frizzled-related protein 1 or Wnt inhibitory factor 1, disrupts bundle orientation. Moreover, Wnt7a is expressed in a pattern consistent with a role in the polarization of the developing stereociliary bundles. We propose that Wnt signaling across the region of developing outer hair cells gives rise to planar polarity in the mammalian cochlea.     

Unexpected High Genetic Diversity at the Extreme Northern Geographic Limit of Taurulus bubalis (Euphrasen, 1786)

The longspined bullhead (Taurulus bubalis, Euphrasen 1786) belongs to the family Cottidae and is a rocky shore species that inhabits the intertidal zones of the Eastern Atlantic since Iceland, southward to Portugal and also the North Sea and Baltic, northward to the Gulf of Finland, with some occurrences in the northern Mediterranean coasts eastward to the Gulf of Genoa. We analysed the phylogeographic patterns of this species using mitochondrial and nuclear markers in populations throughout most of its distributional range in west Europe. We found that T. bubalis has a relatively shallow genealogy with some differentiation between Atlantic and North Sea. Genetic diversity was homogeneous across all populations studied. The possibility of a glacial refugium near the North Sea is discussed. In many, but not all, marine temperate organisms, patterns of diversity are similar across the species range. If this phenomenon proves to be most common in cold adapted species, it may reflect the availability of glacial refugia not far from their present-day northern limits.     

Comparative features of the surface morphology of the basilar papilla in five families of salamanders (Amphibia; Caudata)

The surface morphology of the basilar recess and papilla was examined in 14 species of newts and salamanders selected from the five families of urodeles (Ambystomatidae, Salamandridae, Hynobiidae, Cryptobranchidae, and Amphiumidae) known to have this end-organ. In this sampling, the general organization of basilar structures is essentially similar across species investigated. The recess forms a tubular diverticulum of the proximal part of the lagena. One wall of the recess is associated with a diverticulum of the intracapsular periotic sac, and an adjacent wall is occupied by the basilar papilla. The papilla contained from as few as five hair cells in specimens of Taricha torosa to over 200 hair cells in Cryptobranchus allegheniensis. In most species, the papilla showed a morphological continuum between tall centrally or distally placed ciliary bundles and short ciliary bundles near the papillar margins. In certain species examined, tall bundles had kinocilia with swellings near their tips. Most forms showed a tendency to have groups of ciliary bundles morphologically polarized either toward or away from the saccule. In Cryptobranchus and Dicamptodon, many bundles had a random orientation. The gross and fine structural features of the basilar complex are compared in urodeles and anurans, and "generalized" features for the amphibian basilar complex are suggested. The basilar complex of Cryptobranchus is interpreted as being most generalized, representing a structural form from which most features of the basilar complex in other urodeles and anurans can be derived.     

Anti-tubulin labeling reveals ampullary neuron ciliary bundles in opisthobranch larvae and a new putative neural structure associated with the apical ganglion

This investigation examines tubulin labeling associated with the apical ganglion in a variety of planktotrophic and lecithotrophic opisthobranch larvae. Emphasis is on the ampullary neurons, in which ciliary bundles within the ampulla are strongly labeled. The larvae of all but one species have five ampullary neurons and their associated ciliary bundles. The anaspid Phyllaplysia taylori, a species with direct development and an encapsulated veliger stage, has only four ampullary neurons. The cilia-containing ampulla extends to the pretrochal surface via a long, narrow canal that opens to the external environment through a very small pore (0.1 microm diameter). Cilia within the canal were never observed to project beyond the opening of the apical pore. The ampullary canals extend toward and are grouped with the ciliary tuft cells and remain in this location as planktotrophic larvae feed and grow. If, as has been reported, the ciliary tuft is motile, the pores may be continually bathed in fresh seawater. Such an arrangement would increase sensitivity to environmental chemical stimuli if the suggested chemosensory function of these neurons is correct. In general, ciliary bundles of newly hatched veligers are smaller in planktotrophic larvae than in lecithotrophic larvae. In planktotrophic larvae of Melibe leonina, the ciliary bundles increase in length and width as the veligers feed and grow. This may be related to an increase in sensitivity for whatever sensory function these neurons fulfill. An unexpected tubulin-labeled structure, tentatively called the apical nerve, was also found to be associated with the apical ganglion. This putative nerve extends from the region of the visceral organs to a position either within or adjacent to the apical ganglion. One function of the apical nerve might be to convey the stimulus resulting from metamorphic induction to the visceral organs.     

Study of development of ciliary folds and Zinn's zonules in Rana temporaria L. by means of scanning electron microscopy]

The development of ciliary folds and zonul of Zinn has been studied in the eyes of the common frog Rana temporaria L. by means of scanning electron microscopy. The development of ciliary folds begins at the stage 45 by the flexure of the external layer in the ciliary zone. At the stage 46 this process involves the internal layer and the folds become two-layered. The zonules of Zinn form before the folds of internal layer of the ciliary epithelium begin to form as separate bundles of fibers. At the stage 45 they are already distinct. Later the ciliary filaments fold in 2 felt-like layers -- zonula which pass from the equatorial lens zone and attach near orbiculum ciliaris. In the place of attachment the margin of zonul repeats the relief of folds, thus attaching to their whole surface, and individual filaments go farther, to orbiculum ciliaris. All these processes take place in they eye prior to the beginning of metamorphosis.     

Scanning Electron Microscopy of the Adoral Ciliary Zone of Entodinium Stein (Ciliophora,Entodiniomorphida)1

The adoral ciliary zone of the rumen ciliates, Entodinium spp., was observed topographically in the SEM. The upper side of the anterior end of the body was indented by the vestibulum, which had cilia arranged on its right wall and ribs along the left wall. The adoral ciliary zone could be divided into at least two arrangements. The outer ciliary zone had many membranelle-like structures, which consisted of cilia arranged radially from the body axis. Each membranelle-like structure consisted of two rows of about eight cilia each lining up in a single file. It was, however, different from a typical membranelle, because its cilia were connected with the vestibular cilia and were arranged not spirally but on a plane. These cilia extended toward the outside because of the projecting cytoplasm from which they originated. In contrast, the cilia of the inner ciliary zone were aggregated to form relatively unsystematic bundles. Since the vestibular opening was slanted on the upper side of the body, the ciliary bundles were thick on the lower side and sparse on the upper side of the body. Neither outer nor inner ciliary zones completely surrounded the vestibular opening. The ciliature started from the left side of the vestibular opening, encircled the lower side of the body, and entered the vestibulum from its right side. The functions of these two types of ciliary arrangements are discussed.     

Ultrastructure of the copulatory stylet and accessory spines in Haplopharynx quadristimulus (Turbellaria)

The copulatory organ of Haplopharynx quadristimulus Ax, 1971 (Carolina form, Rieger, 1977) consists of a proximal prostatic vesicle and a distal stylet apparatus comprising a central tubular stylet and four to five peripheral accessory spines. By electron microscopy it could be seen that the stylet and spines were intracellular specializations. The copulatory organ can be interpreted as a specialization of an epithelial canal extending from the testes to the body wall. In the complex stylet apparatus, the epithelium was differentiated into six cell types. The stylet, which was formed in a matrix syncytium next to the prostatic vesicle, extended into the lumen of the stylet canal. The interior of the stylet apparatus contained one group of cells that had thick ciliary rootlets and another that had rootlet-like ribbons.The cells that contain the rootlets enveloped bundles of longitudinally arranged muscles. The accessory spines were formed in cells which lay peripheral to the muscle bundles. The spines, stylet, rootlet-like ribbons, and rootlets had similar patterns of periodic cross striations. The similarity in striation patterns suggests that the accessory spines and stylet are composed of modified ciliary rootlets.     

Scanning Electron Microscopy of the Adoral Ciliary Zone of Cycloposthium Bundle (Ciliophora,Entodiniomorphida)1

The adoral ciliary zone of Cycloposthium spp., inhabiting the large intestine of the horse, was studied by scanning electron microscopy. It could be divided into four parts: outer, inner, left, and right zones. The outer zone, extending on the anterior periphery of the apical cone of the body, had 20 tuft-like syncilia arranged radially around the longitudinal axis. Each ciliary tuft consisted of about 170 cilia, and in cross section it had a rectangular shape. The cilia of the inner zone, situated at the top of the apical cone, were aggregated irregularly to form shorter bundles than the tufts of the outer zone. The innermost cilia of this zone were shorter than the outermost. There was a distinct non-ciliated border between the outer and inner zones. A horseshoe-like operculum having no cilia was present at the center of the adoral ciliary zone, and the opening of the vestibulum was situated as a cleft crossing from the center to the right periphery of this zone. No cilia extended onto the vestibular wall. The left ciliary zone was situated beneath the outer zone and consisted of five short rows of barren kinetosomes of which only the central row possessed very short cilia. The right ciliary zone, consisting of a few rows of cilia situated at the bottom of the inner adoral lip, was also easily distinguished from the other ciliary zones. This zone was interpreted as an extension of the outer adoral zone passing along the right side of the apical cone. These ciliary zones were considered to be highly differentiated and useful for both movement of and ingestion of food.     

Distribution of catecholamine-containing,serotonin-like and neuropeptide FMRFamide-like immunoreactive neurons and processes in the nervous system of the actinotroch larva ofPhoronis muelleri (Phoronida)

Summary Glyoxylic-acid-induced fluorescence of catecholamines and antibodies against serotonin and FMRFamide were used to study the distribution of putative neurotransmitters in the actinotroch larva ofPhoronis muelleri Selys-Longchamps, 1903. Catecholamines occur in the neuropile of the apical ganglion, in the longitudinal median epistome nerves, in the epistome marginal nerves, and in the nerve along the bases of the tentacles. The tentacles have laterofrontal and latero-abfrontal bundles of processes that form two minor nerves along the lateral ciliary band of the tentacles, and a medio-frontal bundle of processes. Monopolar cells are located on the ventro-lateral part of the mesosome. Processes are located along the posterior ciliary band and as a reticulum in the epidermis. Serotonin-like immunoreactive cells and processes are located in the apical ganglion, in the longitudinal median epistome nerves, and as a dorsal and ventral pair of bundles along the tentacle bases. Processes from the latter extend into the tentacles as the medioabfrontal processes. The latero-abfrontal processes form a minor nerve along the ciliary band. The dorsal bundles forms the major nerve ring along the tentacles and processes extend from it to the metasome. Processes are located along the posterior ciliary band. FMRFamide-like immunoreactive cells and processes are found in the apical ganglion, in the longitudinal median epistome nerves and as a pair of lateral epistome processes projecting towards the ring of tentacles. In the tentacles, a pair of latero-frontal processes are found; these form a minor nerve along the ciliary band. A band of cells can be seen along the tentacle ring.     

Scanning electron microscopy of the adoral ciliary zone of Cycloposthium bundle (Ciliophora, Entodiniomorphida)

The adoral ciliary zone of Cycloposthium spp., inhabiting the large intestine of the horse, was studied by scanning electron microscopy. It could be divided into four parts: outer, inner, left, and right zones. The outer zone, extending on the anterior periphery of the apical cone of the body, had 20 tuft-like syncilia arranged radially around the longitudinal axis. Each ciliary tuft consisted of about 170 cilia, and in cross section it had a rectangular shape. The cilia of the inner zone, situated at the top of the apical cone, were aggregated irregularly to form shorter bundles than the tufts of the outer zone. The innermost ciliar of this zone were shorter than the outermost. There was a distinct non-ciliated border between the outer and inner zones. A horseshoe-like operculum having no cilia was present at the center of the adoral ciliary zone, and the opening of the vestibulum was situated as a cleft crossing from the center to the right periphery of this zone. No cilia extended onto the vestibular wall. The left ciliary zone was situated beneath the outer zone and consisted of five short rows of barren kinetosomes of which only the central row possessed very short cilia. The right ciliary zone, consisting of a few rows of cilia situated at the bottom of the inner adoral lip, was also easily distinguished from the other ciliary zones. This zone was interpreted as an extension of the outer adoral zone passing along the right side of the apical cone.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparative and functional studies on the suspensory apparatus of the lens (Mammalia)

Summary The suspensory apparatus of the lens has been studied in two species of placental mammals (dog and horse) and in two species of marsupials (phalanger and wallaby). Particular attention has been paid to the suspensory apparatus of the dog and the phalanger. It has been found that the suspensory apparatus of the lens shows great morphological variability, although some features generally are more common in one species than in the others. For instance, in the dog there is a tendency to form fibrous bundles, an uneven distribution of fibres around the lens, and a fan-like arrangement of these fibres at their attachment to the lens. In the phalanger the fibres are evenly distributed around most of the circumference of the lens and the bundles, if formed, are slender. An area devoid of fibres, described as a diastema,is also present.The morphology of ciliary folds, and of the fibrous bundles and the various types of interconnections between them, have been described and illustrated, and the comparative morphology of the suspensory apparatus of the lens discussed. The reduction of the accommodative mechanism from that situated on both horizontal and vertical planes to that on a horizontal plane only has been discussed. The latter type is found in mammals. The mechanics of the suspensory apparatus of the lens has also been considered and attention given to the rotation of the ciliary folds and the twisting of the fibrous bundles, as observed in the dry specimens. A possible relationship of this finding to the adaptation of the lens has also been discussed. The suggestion has been put forward that the suspensory apparatus of the lens is not only suspensory but also regulatory in function, the regulation depending on its ability to disperse stresses between the ciliary muscle and the lens. The formation of bundles, the existence of interconnecting fibres and interconnecting nets, and the spreading of the fibres of a bundle at its attachment to the lens, are the main factors contributing to the regulation of stresses.The morphology of the suspensory apparatus of the dog and the phalanger was compared with that of man.     

Specific features of centriole formation and ciliogenesis in ciliary epithelium cells of respiratory tracts in patients with Kartagener syndrome

An electron microscopic study of the ciliary epithelium of respiratory tracts was carried out in children (members of the same family) with Kartagener syndrome, which is a variant of ciliary dyskinesia. It was shown that in the case of both mobile cilia and ciliary dyskinesia in man, centrioles are formed during formation of the ciliary basal bodies predominantly de novo, involving deuterosomes. A wide spectrum of pathological changes was described in literature, such as the absence of dynein arms in the axoneme and disorganization of axoneme structure. In addition to these changes in the ciliary system, we found integration of several ciliary axonemes by the same plasma membrane, running of microtubules from the plasma membrane as bundles, different orientation of basal legs, etc.     

Meiotic peculiarities in hybrid buffalo

The two varieties of the Water buffalo (Bubalis bubalis var. bubalis and Bubalis bubalis var. carabao) have 2n = 50 and 2n = 48 karyotypes, respectively. The F1 hybrids are thought to exhibit a karyotype of 2n = 49 and are known to be fertile. Meiosis was studied in 10 hybrid water buffalo bulls. Karyotypes of the bulls were prepared from leukocyte cultures and testicular biopsy samples in a routine manner and examined. Phenotypically the bulls showed characteristics of the hybrid buffalo. Five of the bulls carried 2n = 50 and 5 had 2n = 49. Multivalent chromosomes were found in diakinesis (metaphase I) cells of bulls with 2n = 49 karyotypes. Synapses were found in bulls of both karyotypes.     

Specific Features of Centriole Formation and Ciliogenesis in Ciliary Epithelium Cells of Respiratory Tracts in Patients with Kartagener Syndrome

An electron microscopic study of the ciliary epithelium of respiratory tracts was carried out in children (members of the same family) with Kartagener syndrome, which is a variant of ciliary dyskinesia. It was shown that in the case of both mobile cilia and ciliary dyskinesia in man, centrioles are formed during formation of the ciliary basal bodies predominantly de novo, involving deuterosomes. A wide spectrum of pathological changes was described in literature, such as the absence of dynein arms in the axoneme and disorganization of axoneme structure. In addition to these changes in the ciliary system, we found integration of several ciliary axonemes by the same plasma membrane, running of microtubules from the plasma membrane as bundles, different orientation of basal legs, etc.__________Translated from Ontogenez, Vol. 36, No. 3, 2005, pp. 190–198.Original Russian Text Copyright © 2005 by Domaratskii, Uvakina, Volkov, Onishchenko.     

The molecular basis of mechanisms underlying polarization vision

The underlying mechanisms of polarization sensitivity (PS) have long remained elusive. For rhabdomeric photoreceptors, questions remain over the high levels of PS measured experimentally. In ciliary photoreceptors, and specifically cones, little direct evidence supports any type of mechanism. In order to promote a greater interest in these fundamental aspects of polarization vision, we examined a varied collection of studies linking membrane biochemistry, protein-protein interactions, molecular ordering and membrane phase behaviour. While initially these studies may seem unrelated to polarization vision, a common narrative emerges. A surprising amount of evidence exists demonstrating the importance of protein-protein interactions in both rhabdomeric and ciliary photoreceptors, indicating the possible long-range ordering of the opsin protein for increased PS. Moreover, we extend this direction by considering how such protein paracrystalline organization arises in all cell types from controlled membrane phase behaviour and propose a universal pathway for PS to occur in both rhabdomeric and cone photoreceptors.     

Functional correlates of degeneration and renewal of cilia and knobs of olfactory receptor neurons in the frog

Changes in surface structures of the olfactory epithelium, olfactorynerve and olfactory nerve layer in the olfactory bulb followingolfactory nerve section were studied, by scanning electron microscopy,in the frog. Correlative neurophysiological responses were recordedfrom the olfactory epithelium in response to odor stimulation.Examination of the epithelial surface showed degeneration andloss of the dense ciliary matrix and olfactory knobs by day10, which exposed the microvillar surface of the sustentacularcells. The amplitude of slow voltage transients recorded fromthe epithelial surface systematically decreased through day10. By day 40, the olfactory epithelium became responsive toodor stimulation. At this time partial renewal of the ciliarymatrix on the epithelial surface and bundles of receptor cellaxons in the olfactory nerve layer of the olfactory bulb wereobserved. There was substantial replacement of the ciliary matrixby day 100; in contrast, considerably less recovery of the slowvoltage transient was evident. Recovery of odor-evoked responsivity lagged behind recovery of the ciliary matrix. Therefore,these data imply that the reappearance of olfactory knobs andcilia is causally related to the recovery of the slow voltagetransients.     

Polymorphism and gene organization of water buffalo MHC-DQB genes show homology to the BoLA DQB region

In cattle (Bos taurus), there is evidence of more than 50 alleles of BoLA-DQB (bovine lymphocyte antigen DQB) that are distributed across at least five DQB loci, making this region one of the most complex in the BoLA gene family. In this study, DQB alleles were analysed for the water buffalo (Bubalus bubalis), another economically important bovine species. Twelve alleles for Bubu-DQB (Bubalis bubalis DQB) were determined by nucleotide sequence analysis. A phylogenetic analysis revealed numerous trans-species polymorphisms, with alleles from water buffalo assigned to at least three different loci (BoLA-DQB1, BoLA-DQB3 and BoLA-DQB4) that are also found in cattle. These presumptive loci were analysed for patterns of synonymous (d(S)) and non-synonymous (d(N)) substitution. Like BoLA-DQB1, Bubu-DQB1 was observed to be under strong positive selection for polymorphism. We conclude that water buffalo and cattle share the current arrangement of their DQB region because of their common ancestry.     

Cytoskeletal elements in arthropod sensilla and mammalian photoreceptors.

Ciliary receptor cells, typified by cilia or modified cilia, are very common in the animal kingdom. In addition to the cytoskeleton of their ciliary processes these receptors possess other specific prominent cytoskeletal elements. Two representative systems are presented: i) scolopidia, mechanosensitive sensilla of various arthropod species; and ii) photoreceptor cells of the retina of the bovine eye. Two cytoskeletal structures are characteristic for arthropod scolopidia: a scolopale typifies the innermost auxiliary cell, and long ciliary rootlets are extending well into the sensory cells. The latter element is also characteristic for the inner segment of the photoreceptor cells in bovine. The scolopale of scolopidia is mainly composed of actin filaments. In the absence of myosin, the uniform polarity of the actin filaments and their association with tropomyosin all indicate a stabilizing role of the filament bundles within the scolopale. This function and a certain elasticity of actin filament bundles may be important during stimulation of the sensilla. The ciliary rootlets of both systems originate at the basal bodies at the ciliary base of the sensory cells and project proximally. These rootlets are composed of longitudinally oriented, fine filaments forming a characteristic regular cross-striation. An alpha-actinin immunoreactivity was detected within the ciliary rootlets of scolopidia. In addition, antibodies to centrin react with the rootlets of both types of receptors. Since centrin is largely responsible for the contraction of the flagellar rootlets in green algae, contraction may also occur in the ciliary rootlets of insect sensilla and vertebrate photoreceptors. In both systems, contraction or relaxation of the ciliary rootlets could serve in sensory transduction or adaptation.