1,721,073 research outputs found
Immunocytochemistry of carbonic anhydrase in the chick embryo membranous labyrinth during development.
No full textAnalysis of otospiralin down-regulation and acoustic damage to organ of Corti in guinea pig.
No full textNoise over-stimulation induces or influences molecular pathways in the cochlea. One approach to the identification of the components of these pathways is to examine genes and proteins that change after the different types and levels of stress. Quantitative RT-PCR was used to understand if there were changes in the expression of proteins not directly involved in perception of sound consequently to white noise administration. We found a downregulation of mRNA level of otospiralin, a protein expressed by fibrocytes in the cochlea of guinea pigs, after white noise over-stimulation at 108 dB SPL. This level of noise caused a temporary threshold shift (TTS) after 2h and a permanent threshold shift (PTS) after 5h. This could indicate that otospiralin is directly involved in ion homeostasis in endolimph. On the other hand one cannot exclude that the down-regulation of otospiralin could alter the fibrocytes themselves and indirectly perturb hair cells metabolism. By using in situ hybridization we have showed that there was not relevant change in cell types expressing otospiralin after noise stress. In order to determine whether there was damage together with TTS, we have examined, by SEM analysis, the hair cells fate in the organ of Corti after exposure to white noise. After 2 h of treatment the damage is mainly evident to the 2nd and 3rd rows of outer hair cells whereas inner hair cells are no compromised. Apical turn outer hair cells are more vulnerable to damage than basal ones. After 1 month from over-stimulation, in agreement with the measure of the TTS, there is a recovery only in the specimens treated for 2 h.
We can conclude that, consequently to the administration of white noise for 2 h, the sensorial epithelium is able to recover the damage because the cells are only weakly damaged. On the contrary white noise over-stimulation for 5h, lead to the death of sensorial cells, probably for ROS induced apoptosis, and the epithelium is no more able to recover the damage
THE AMPULLAE OF THE INNER EAR IN THE LIZARD PODARCIS S. SICULA. ULTRASTRUCTURAL ASPECTS
No full textThe inner ear ampullae of the lizard Podarcis s. sicula were studied to determine better the ultrastructure of ampullar epithelial cells. Our study confirmed that the ampullae of the membranous labyrinth of this lizard are similar to those of other vertebrates in their ultrastructural aspect. Moreover, our observations revealed a special type of dark cells, restricted to a small area of the crista. They appeared similar to type II sensory cells and showed a dark, finely granular cytoplasm, containing numerous mitochondria and ribosomes, extensive Golgi apparatus and abundant glycogen. The morphology of these cells suggests that they may be special sensory cells, or different stages of sensory cells, probably implied in the crista cell turnover described for some vertebrate groups
THE AMPULLAE OF THE INNER EAR IN THE LIZARD PODARCIS S. SICULA. ULTRASTRUCTURAL ASPECTS
No full textThe inner ear ampullae of the lizard Podarcis s. sicula were studied to determine better the ultrastructure of ampullar epithelial cells. Our study confirmed that the ampullae of the membranous labyrinth of this lizard are similar to those of other vertebrates in their ultrastructural aspect. Moreover, our observations revealed a special type of dark cells, restricted to a small area of the crista. They appeared similar to type II sensory cells and showed a dark, finely granular cytoplasm, containing numerous mitochondria and ribosomes, extensive Golgi apparatus and abundant glycogen. The morphology of these cells suggests that they may be special sensory cells, or different stages of sensory cells, probably implied in the crista cell turnover described for some vertebrate groups
Only complete rejoining of DNA strand breaks after UVC allows K562 cell proliferation and DMSO induction of erythropoiesis
Full text linkDNA strand breaks are early intermediates of the repair of UVC-induced DNA damage, however, since they severely impair cellular activities, their presence should be limited in time. In this study, the effects of incomplete repair of UVC-induced DNA strand breaks are investigated on K562 cell growth and the induction of erythroid differentiation by addition of DMSO to the cell culture medium. The kinetics were followed after UV irradiation by single cell gel electrophoresis, and in total cell population by alkaline or neutral agarose gel electrophoresis. Shortly after exposure, an extensive fragmentation occurred in DNA; DNA double strand breaks were negatively correlated with recovery time for DNA integrity. DNA damage induced by UVC 9 J/m2 rapidly triggered necrosis in a large fraction of irradiated K562 cells, and only 40% of treated cells resumed growth at a very low rate within 24 h of culture. The addition of DMSO to the culture medium of cells 15 min after UVC, when DNA strand break repair was not yet complete, produced apoptosis in >70% of surviving cells, as determined by TUNEL assay. Conversely, if DMSO was added when the resealing of DNA strand breaks was complete, surviving K562 cells retained full growth capacity, and their progeny underwent erythroid differentiation with normal levels of erythroid proteins, d-aminolevulinic acid dehydrase and hemoglobin. This study shows that the extent of DNA strand break repair influences cell proliferation and the DMSO induced erythroid program,and the same UVC dose can have opposite effects depending on cellular status
Scanning electron microscopy and X-ray diffraction studies of the macular crystals in the Chondrostean fish Erpetoichthys calabaricus (Smith).
No full textMorphologic and crystallographic studies of the otoliths of the reed‐fish Erpetoichthys calabaricus showed (1) aragonite statoliths with a serrated surface, and (2) two populations of statoconia: one of numerous discoid biconvex crystals of vaterite, the other of pseudohexagonal crystals of aragonite. We suggest that the presence of two calcium carbonate polymorphs in the statoacoustic organs of this archaic fish may have an evolutionary, as well as a systematic and functional significance. 1992 The Royal Swedish Academy of Science
Ruolo della proteina ORY nella spermiogenesi in Drosophilamelanogaster
No full textUnlike humans and other placental mammals, in which masculinity is due to a dominant effect of the Y chromosome, this chromosome in Drosophila melanogaster does not play any role in sex determination, which is determined by the ratio of X chromosomes and autosomal arrangements. An X0 individual is, in fact, male but sterile demonstrating that the Y chromosome contains genes important for male fertility. Among these has been identified and mapped the gene Ory (AB Carvalho et al., 2001), characterized by a series of coiled-coil motifs contained in molecules such as those of the heavy chains of myosin, with which, however, there is no orthology.
After gene Ory silencing, males of Drosophila m. have infertility as a primary phenotype. In this work we also examined the role that the protein ORY might have in the sperm formation. TEM analysis of the mutant testes showed a series of morphological changes during spermiogenesis in varying degrees, in particular changes are evident in the development stages of spermatids after post-elongation; these spermatids, in fact, came to the stage of individualization but did not differentiate in mature sperm. The following CLSM analysis has also highlighted that the investment cones, individualization actinic-based structures, were not moving correctly along the axonemes of spermatids, remaining associated with the base of the nuclei of cells in elongation.
So it appears that the protein ORY is involved in proper progress of the individualization complex during spermiogenesis. It remain to be clarified the proteins and the manner in which ORY interacts in individualization complex and understand the molecular mechanism that allows it to intervene in the advancement of the cones
Immunocytochemistry of carbonic anhydrase and non-radioactive detection of its RNA by in situ hybridization in the chick embryo membranous labyrinth
No full textAn immunocytochemical study was carried out with the aim to localize carbonic anhydrase isozymes (CA I and CA II) in the chick membranous labyrinth. CA I and CA II were localized in the same cells and, during the early developmental stages, were diffusely present in the labyrinthine epithelium. At later stages, the sensorial epithelium of the maculae acusticae, crista ampullaris and papilla basilaris, as well as labyrinthine dark cells and the epithelium of the endolymphatic sac strongly stained by the immunocytochemical procedure. In 1-day and 1-week old chicks, CA was present in the same sites as at advanced embryonal stages. In order to detect mRNA for carbonic anhydrase II, in situ hybridization was also used. Strong hybridization signals were observed in the sensorial epithelium of the saccule, utricle and crista ampullaris, in the tegmentum vasculosum, the endolymphatic sac, the erythrocytes and the choroid plexus in embryos older than 10 days. This positivity persisted until the day after hatching
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