Search Results (8)

In eukaryotes, a lot of proteins are transported across the endoplasmic reticulum by the heterotrimeric Sec61 channel. And post-translational transport needs another Sec62/Sec63 complex. However, functions of these genes are poorly explored in insects. In this study, we first identified five Sec genes, named Sec61α, Sec61β, Sec61γ, Sec62 and Sec63, in Locusta migratoria. Quantitative reverse-transcription polymerase chain reaction (RT-qPCR) analysis showed that these five genes were expressed in muti-tissues, including wing pad, leg, foregut, midgut, gastric cecum, hindgut, and highly expressed in the integument. Knockdown of LmSec61α and LmSec61γ by RNA interference (RNAi) lead to the feeding cessation with a mortality rate of 100%. However, there is only 13.4% of dsLmSec61β-injected nymphs died before molting. All nymphs injected with dsLmSec61α and dsLmSec61γ died before molting with the gut atrophy. Furthermore, hematoxylin–eosin staining indicated that the cells of the midguts and gastric caecum were defective, and the microvilli and peritrophic matrix were destroyed seriously after silencing LmSec61α and LmSec61γ. Knockdown of LmSec62 and LmSec63 resulted in high mortality before and during molting. The hematoxylin–eosin (HE) staining and transmission electron microscopy (TEM) results showed that both the formation of the new cuticle and the degradation of the old cuticle were inhibited in dsLmSec63-injected insects compared to the controls. Especially, there was no obvious plaques on microvillar tips of the epidermal cells after silencing of LmSec63. These results revealed that Sec61s and Sec62/Sec63 genes are required in the gut and cuticle development of locusts. Therefore, these genes are potential targets for the control of locusts. Full article

The ORA (olfactory receptor class A) gene family in teleosts is related to the V1R (vomeronasal 1 receptors) family in mammals and plays a key role in odor detection. Although ORA genes have been identified in several teleosts, their characteristics in mandarin fish (Siniperca chuatsi) have not been explored. In this study, we conducted a comprehensive genomic analysis of the mandarin fish and discovered a complete ORA gene family consisting of five members located on chromosome 2 (ORA1, ORA2, ORA3, ORA4) and chromosome 16 (ORA6). Phylogenetic, synteny, and gene structure analyses revealed typical exon–intron conservation with strong evidence of purifying selection. Tissue expression analysis showed distinct expression profiles for each ORA gene, with some showing sexual dimorphism in specific tissues. The expression of ORA1 and ORA2 in the olfactory epithelium exhibits sexual dimorphism, while ORA3 shows sexual dimorphism in the brain. In situ hybridization confirmed that ORA1, ORA2, ORA3, and ORA6 are expressed in the microvillar sensory neurons of the olfactory epithelium, while ORA4 is expressed in crypt cells. Additionally, molecular docking simulations indicated that the five ORA proteins have a high binding affinity with seven bile acids (LAC, GLAC, CA, TLCA, 3-KLCA, 7-KLCA, and 12-KLCA), with ORAs showing stronger binding affinity with LCA and CA. This study comprehensively characterizes the ORA gene family in mandarin fish, examining its phylogeny, synteny, gene structure, and selection pressure. Furthermore, we found that each ORA displays a distinct expression pattern across multiple tissues, with notable sexual dimorphism, and shows potential binding interactions with specific bile acids and pheromones. Our findings provide valuable insights that enhance the overall understanding of fish ORAs and their potential functions. Full article

Microvilli are bristle-like protuberances of the plasma membrane, which express the vitality of mucous and epithelial cells; their alteration indicates a condition of cellular suffering in a predictive sense, making it possible to establish how much an inflammatory state or toxic conditions affect cellular functionality. In this article, the authors evaluate the applications of scanning electron microscopy (SEM) examination to impression cytology (IC) of the bulbar conjunctiva for the assessment of microvillar alteration as an early ultrastructural indicator of ocular surface health. This method offers several advantages, starting with its simplicity: it involves the non-invasive application of a strip of bibulous paper to the bulbar or tarsal conjunctiva. Unlike conjunctival or corneal biopsies, which are surgical procedures, this technique is far less invasive and more comfortable for the patient. It also provides a more clinically relevant in vivo assessment compared to studies on cultured cell lines, which are mostly limited to scientific research and may not accurately reflect real-world conditions. This makes it an effective, repeatable, and patient-friendly option for detecting early pathological alterations of the ocular surface. It also represents a useful tool for evaluating the efficacy of topical drugs and the toxic effects of external factors and ophthalmic or systemic diseases. Finally, it allows for obtaining accessory information relating to goblet cells, the presence of inflammatory infiltrate, or any pathogens. Full article

The authors performed an ex vivo and in vivo evaluation of the ultrastructural effects on the conjunctival epithelial cells of a new multiple-action tear substitute containing cross-linked hyaluronic acid, lipids and trehalose (Trimix^®), using scanning electron microscopy (SEM) with conjunctival impression cytology. The ex vivo study highlights the persistence and distribution of the product at 5 and 60 min on a monolayer of conjunctival epithelial cells and an increase in microvilli density at the 60 min evaluation. In vivo examination was conducted on three subjects with different grades of ocular surface inflammation, treated with one drop of the product twice daily for thirty days. At the baseline (T₀) and twelve hours after the last administration of the tear drop (T₃₀), impression cytology of the upper bulbar conjunctiva for SEM evaluation of conjunctival epithelial cells was carried out. Slit lamp examination (SLE), corneal and conjunctival Fluotest, tear film break-up time (TBUT), and ocular surface disease index (OSDI) questionnaires were also performed to correlate the ultrastructural results with the clinical findings. After 30 days of treatment, a significant improvement in all clinical and symptomatic parameters and in the condition of the ocular surface was detected, with microvillar regeneration and strengthening in all the patients, and a complete restoration in 2/3 of them. The persistence and distribution of the product on the epithelial cells was also noted 12 h after the last administration. The results, therefore, suggest a marked epitheliotropic effect along with a high residence time of the tear substitute. Full article

In sea urchin, the immediate contact of the acrosome-reacted sperm with the egg surface triggers a series of structural and ionic changes in the egg cortex. Within one minute after sperm fuses with the egg plasma membrane, the cell membrane potential changes with the concurrent increases in intracellular Ca²⁺ levels. The consequent exocytosis of the cortical granules induces separation of the vitelline layer from the egg plasma membrane. While these cortical changes are presumed to prevent the fusion of additional sperm, the subsequent late phase (between 1 and 4 min after fertilization) is characterized by reorganization of the egg cortex and microvilli (elongation) and by the metabolic shift to activate de novo protein and DNA syntheses. The latter biosynthetic events are crucial for embryonic development. Previous studies suggested that the early phase of fertilization was not a prerequisite for these changes in the second phase since the increase in the intracellular pH induced by the exposure of unfertilized sea urchin eggs to ammonia seawater could start metabolic egg activation in the absence of the cortical granule exocytosis. In the present study, we have demonstrated that the incubation of unfertilized eggs in ammonia seawater induced considerable elongations of microvilli (containing actin filaments) as a consequence of the intracellular pH increase, which increased the egg’s receptivity to sperm and made the eggs polyspermic at fertilization despite the elevation of the fertilization envelope (FE). These eggs also displayed compromised Ca²⁺ signals at fertilization, as the amplitude of the cortical flash was significantly reduced and the elevated intracellular Ca²⁺ level declined much faster. These results have also highlighted the importance of the increased internal pH in regulating Ca²⁺ signaling and the microvillar actin cytoskeleton during the late phase of the fertilization process. Full article

Background and Aim: Diarrhea, abdominal pain, and bloating are frequent in irritable bowel syndrome (IBS)-like disorders, although little is known about their intestinal ultrastructural alterations. The aim of the present study was to study duodenal biopsies from IBS-like patients to find ultrastructural alterations. Materials and Methods: Study design: descriptive comparative pilot study. Thirty outpatients (9 male and 21 female; median age 37.7 years; range, 20 to 65 years) complaining of IBS-like symptoms were enrolled between January 2015 to May 2019 and were divided into 6 groups, each equally consisting of 5 patients: (A) untreated celiac disease (uCD); (B) treated celiac disease (tCD); (C) wheat allergy (WA); (D) Non-celiac gluten sensitivity (NCGS); (E) Nickel allergic contact mucositis (Ni ACM); (F) controls affected by GERD. Transmission electron microscopy (TEM) morphological characteristics were: microvilli length, intermicrovillar distance, junctional complexes (JC) gap width, autophagic bodies, apoptosis, altered mitochondria, lipid/chylomicron droplets, and mast cells. Regarding JC, we focused on tight junctions (TJ), adherens junctions (AJ), and desmosomes. Results: Major alterations in microvilli length and intermicrovillar distance have been observed in the subjects affected by uCD. Microvilli of tCD patients showed marked recovery after adequate GFD, although not comparable to controls. Intermediate microvillar alterations were instead observed in NCGS and Ni ACM, while characteristics of WA subjects appeared more similar to tCD. Regarding JC, TJ did not show significant differences between all groups studied, including controls. The AJ were significantly more dilated in all groups compared to controls, while no significant differences were found between the pathological groups. The distance between desmosomes was greater in uCD, NCGS, and Ni ACM than in tCD, WA, and controls. Finally, intracellular alterations have been detected in most of the groups studied although they seemed more unspecific. Conclusions: TEM analysis confirmed damages to the intestinal barrier and defense mechanisms by enterocytes in IBS-like patients, probably linked to low-grade inflammation or adverse reactions triggered by food allergens, heavy metals, or other unknown. On the other hand, our study needs confirmation and further investigations with larger populations to facilitate diagnosis, therapy, and prevention of IBS-like disorders in the future. Full article

Patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 2019, suffer from respiratory and non-respiratory symptoms. Among these symptoms, the loss of smell has attracted considerable attention. The objectives of this study were to determine which cells are infected, what happens in the olfactory system after viral infection, and how these pathologic changes contribute to olfactory loss. For this purpose, Syrian golden hamsters were used. First, we verified the olfactory structures in the nasal cavity of Syrian golden hamsters, namely the main olfactory epithelium, the vomeronasal organ, and their cellular components. Second, we found angiotensin-converting enzyme 2 expression, a receptor protein of SARS-CoV-2, in both structures and infections of supporting, microvillar, and solitary chemosensory cells. Third, we observed pathological changes in the infected epithelium, including reduced thickness of the mucus layer, detached epithelia, indistinct layers of epithelia, infiltration of inflammatory cells, and apoptotic cells in the overall layers. We concluded that a structurally and functionally altered microenvironment influences olfactory function. We observed the regeneration of the damaged epithelium, and found multilayers of basal cells, indicating that they were activated and proliferating to reconstitute the injured epithelium. Full article

(1) Background: The unusual accumulation of Na,K-ATPase complexes in the brush border membrane of choroid plexus epithelial cells have intrigued researchers for decades. However, the full range of the expressed Na,K-ATPase subunits and their relation to the microvillus cytoskeleton remains unknown. (2) Methods: RT-PCR analysis, co-immunoprecipitation, native PAGE, mass spectrometry, and differential centrifugation were combined with high-resolution immunofluorescence histochemistry, proximity ligase assays, and stimulated emission depletion (STED) microscopy on mouse choroid plexus cells or tissues in order to resolve these issues. (3) Results: The choroid plexus epithelium expresses Na,K-ATPase subunits α1, α2, β1, β2, β3, and phospholemman. The α1, α2, β1, and β2, subunits are all localized to the brush border membrane, where they appear to form a complex. The ATPase complexes may stabilize in the brush border membrane via anchoring to microvillar actin indirectly through ankyrin-3 or directly via other co-precipitated proteins. Aquaporin 1 (AQP1) may form part of the proposed multi-protein complexes in contrast to another membrane protein, the Na-K-2Cl cotransporter 1 (NKCC1). NKCC1 expression seems necessary for full brush border membrane accumulation of the Na,K-ATPase in the choroid plexus. (4) Conclusion: A multitude of Na,K-ATPase subunits form molecular complexes in the choroid plexus brush border, which may bind to the cytoskeleton by various alternative actin binding proteins. Full article