Segment Membranes Research Articles

Expansion and identification of primary rat aortic vascular stem cells in vitro

To culture and expand primary rat aortic vascular stem cells in vitro and evaluate their characteristics as mesenchymal stem cells. The thoracic and abdominal aortas isolated from 2- to 3-week-old Sprague-Dawley rats were cut into vascular segments 2.0 mm in length and cultured in culture flasks till adhesion and solidification of the outer membranes. The primary cells were further cultured to 80%-90% confluence before passaging. The morphology and growth characteristics of the cells were observed under a microscope, and the expressions of surface marker CD molecules on the cells was analyzed using flow cytometry. Adipogenic and osteogenic differentiation assays were performed to assess the capacity of the cells for multilineage differentiation. After 3 days of culture, a small number of spindle, star-shaped or polygonal cells migrated out from the peripheral of the vascular segments. At 5-6 days, island-like cell clusters occurred and the cells began to proliferate rapidly. The cell clusters expanded radially and showed signs of cell cloning. At 7-8 days, the cells fused into sheets and displayed a vortex-like distribution. The cells in the third passage presented with a uniform morphology, showing a typical fibroblast-like arrangement. Flow cytometry showed that the cells expressed predominantly CD44 (80.3%), CD73 (62.2%) and CD90 (46.8%) with low expressions of CD34 (1.1%), CD45 (0.2%) and CD11b/c (0.2%). Adipogenic and osteogenic differentiation experiments demonstrated that the cells were capable of lipogenic and osteogenic differentiation in vitro. Rat aortic vascular stem cells with mesenchymal stem cell characteristics can be successfully isolated and cultured by adherent culture of the segmented outer membrane.

Investigation of current density and temperature distribution characteristics under transient conditions based on a 108 cm2 segmented proton exchange membrane fuel cell

Visualizing the electrochemical and temperature distribution characteristics inside proton exchange membrane fuel cell (PEMFC) should greatly contribute to the product development and performance optimization. In the study, a customized 27-segment 108 cm2 fuel cell was fabricated based on the printed circuit board methodology to achieve the local current density and local voltage measurement. In addition, 27 thermocouples were embedded in the segmented cathode graphite gas flow plate for local temperature measurement. Detailed information of fuel cell core components, multi-channel data acquisition system, external temperature control system, and uncertainty analysis was presented. According to the test results of 4000 s current rising conditions and 2400 s current decreasing conditions, the measurement deviation of total current between data acquisition system and TOYO test station is 2.4%–3.2%. Meanwhile, the deviation of output voltage ranges from 0.1% to 2.6%. To quantify the degree of distribution non-uniformity, the range and standard deviation of local parameter values as well as contour map are demonstrated. The non-uniformity of local current density and local temperature becomes more significant under higher operating current conditions. Furthermore, the degree of parameter non-uniformity is more noticeable under current rising conditions compared with current decreasing conditions. The transient increase of operating current leads to the sudden overshoot phenomena of local current range, and the change of local current density among all segments is instantaneously finished. However, the range of current demonstrates relatively smooth transition trends when reactant flow rate rises. Higher temperature area appears in the middle of membrane electrode assembly, especially in the position with higher local current density. The parameter distribution and transition characteristics could provide helpful guidance for fuel cell optimization and diagnosis.

Factors affecting the formation of delayed bitterness in sweet orange (Citrus sinensis (L.) Osbeck) juice

Formation of delayed bitterness is an intractable problem in the processing of citrus juice. This study analyzed the distribution of main bitter-causing substances in sweet orange and the effect of heat treatment, storage temperature, clarification, and homogenization on the limonin content in sweet orange juice. The segment membrane accounted for 34–42% of limonin in the fruit and 21–45% of limonoate A-ring lactone (LARL). Heat treatment accelerated the formation of limonin in juice. Pectinase treatment appeared to facilitate the formation of limonin by reducing the pH of juice. In addition, refrigeration at 4 °C was found to restrain the formation of limonin in juice by inhibiting the activity of limonin D-ring lactone hydrolase (LDLH). In conclusion, segment membrane may have a great contribution to the delayed bitterness of sweet orange juice due to its abundant LARL. These results may provide some guidance for citrus processing and bitterness removal.

Spatial distribution characteristics in segmented PEM fuel cells: Three-dimensional full-morphology simulation

Segmented proton exchange membrane (PEM) fuel cells are widely implemented in measuring their internal spatially distributed variables (e.g. current density and temperature). However, the difference between the segmented and ordinary fuel cells in spatial distribution characteristics has not been fully understood. In this work, we studied the spatial distribution characteristics in segmented fuel cells (cell area: 366.6 cm2) utilizing a three-dimensional (3D) large-scale fuel cell model that considers the full morphologies of metallic bipolar plates (BPs) and dot-matrix hydrogen, air and coolant flow distribution zones, including the current density, temperature, water content, etc., and compared with those in ordinary fuel cells. It is found that placing a segmented print circuit board (PCB) next to the bipolar plate (BP) component has little influence on fuel cell performance and internal distribution characteristics, whereas the measured current density distribution in the PCB still has inconsistency with that in the ordinary fuel cell, indicating that the influence of segmentation on electron conduction cannot be neglected. In the fuel cell with segmented BP and PCB, the fuel cell performance decreases significantly mainly due to increased electrical and ionic ohmic loss. In addition, the BP's segmentation significantly influences on the water and thermal state inside the whole fuel cell, leading to inconsistency in the measured temperature, relative humidity (RH) and current density distributions with ordinary fuel cells.

Dynamics of morphological changes in the cellular layers of retina in the long-term experimental opioid exposure

Relevance of research. There is enough information in the foreign and domestic specialized literature on the issue of morphological reorganization of cells and tissues during experimental opioid exposure and other types of toxic effects on the body today. At present, the issue of structural reorganization in the layers of the retina and disruption of its blood supply processes during subchronic and chronic periods of experimental opioid exposure remains unclear. That is why we decided to supplement, expand and deepen information about these processes by conducting our own research in this direction. The purpose of the study is to clarify the dynamics of pathomorphological changes in the layers of the retina and the links of its hemomicrocirculatory channel in the long term of experimental opioid exposure.Material and methods. The research material was sexually mature, outbred, white male rats, 56 animals in number, weighing 160-270 g, aged 4.5-7.5 months. The initial dose of nalbuphine during the first 2 weeks was 0.212 mg/kg, the next 2 weeks (III-IV weeks) – 0.225 mg/kg, the next (V-VI weeks) – 0.252 mg/kg, the next (VI-VIII weeks ) – 0.260 mg/kg, the next (VIII – X weeks) – 0.283 mg/kg, the next (X – XII weeks) – 0.3 mg/kg, and during (XII – XIV weeks) – 0.45 mg/ kg. Before taking the material of the experimental site, the animal was removed from the experiment with the help of diethyl ether. Rat eyeballs were used as a material for ultrastructural research, considering the preservation of the topographic ratio of the eye membranes. Ultrastructural preparations were prepared according to the generally accepted method. Research results. At the end of the eighth week and the tenth week, persistent hyperemia of the choroidal vessels, degenerative and necrotic changes in the cells of the pigment layer, degeneration of the outer segments of photoreceptors, shortening and fragmentation of mitochondrial cristae of the inner segments of photoreceptors, necrotic changes in the nuclei of individual photoreceptors, degeneration of axons of the outer and inner reticular layers, as well as degenerative and necrotic changes of bipolar and amacrine cells, hypertrophy of processes of Müller cells, degeneration of ganglion cells, hyperemia and perivascular edema of vessels of the outer and inner reticular layers were revealed. After twelve and fourteen weeks, the initial stages of development with subsequent progression of sclerotic changes of Bruchʹs membrane were first detected. The phenomena of degenerative and necrotic changes in the cells of the pigment layer, destruction of the membrane of the outer segments of photoreceptors, degenerative changes in the axons of the outer and inner reticular layers and the layer of nerve fibers, degenerative and necrotic changes in bipolar and amacrine cells, hypertrophic changes in processes of Muller cells, hyperemia and stasis gradually increased, perivascular swellings in the vessels of the inner reticular layer, ganglionic layer and layer of nerve fibers, reactive changes in Muller cells and protoplasmic astrocytes. Conclusion. In the long-term course of experimental opioid exposure, irreversible pathomorphological changes occurred and subsequently progressed, which were caused by an increase in dyscirculatory manifestations in the superficial and deep vascular networks of the retina, causing the deepening of edema phenomena with further compression and hypoxia in the thickness of the retinal layers.

Molecular physiology for the increase of soluble sugar accumulation in citrus fruits under drought stress

To investigate the mechanism for drought promoting soluble sugar accumulation will be conducive to the enhancement of citrus fruit quality as well as stress tolerance. Fruit sucrose mainly derives from source leaves. Its accumulation in citrus fruit cell vacuole involves in two processes of unloading in the fruit segment membrane (SM) and translocating to the vacuole of fruit juice sacs (JS). Here, transcript levels of 47 sugar metabolism- and transport-related genes were compared in fruit SM or JS between drought and control treatments. Results indicated that transcript levels of cell wall invertase genes (CwINV2/6) and sucrose synthase genes (SUS2/6) in the SM were significantly increased by the drought. Moreover, transcript levels of SWEET genes (CsSWEET1/2/4/5/9) and monosaccharide transporter gene (CsPMT3) were significantly increased in SM under drought treatment. On the other hand, SUS1/3 and vacuolar invertase (VINV) transcript levels were significantly increased in JS by drought; CsPMT4, sucrose transporter gene 2 (CsSUT2), tonoplast monosaccharide transporter gene 2 (CsTMT2), sugar transport protein gene 1 (CsSTP1), two citrus type I V-PPase genes (CsVPP1, and CsVPP2) were also significantly increased in drought treated JS. Collectively, the imposition of drought stress resulted in more soluble sugar accumulation through enhancing sucrose download by enhancing sink strength- and transport ability-related genes, such as CwINV2/6, SUS2/6, CsSWEET1/2/4/5/9, and CsPMT3, in fruit SM, and soluble sugar storage ability by increasing transcript levels of genes, such as CsPMT4, VINV, CsSUT2, CsTMT2, CsSTP1, CsVPP1, and CsVPP2, in fruit JS.

Using pectinase enzymatic peeling for obtaining high-quality Huyou (Citrus changshanensis) segments

Huyou (Citrus changshanensis) is a toothsome and nutritious fruit, but its consumption is hindered due to the nonedible segment membranes. The use of pectinase in citrus peel hydrolysis has proven to be an effective strategy for obtaining high-quality citrus segments. In this study, Huyou segments were obtained by three different methods: hand peeling (HP), enzymatic peeling (EP), and chemical peeling (CP). The analysis focused on evaluating the chemical constituents, bitter substances, and color properties of the segments following various treatments. Scanning electron microscopy characterization and molecular docking assays verified the enzyme-substrate interaction during the enzymatic hydrolysis of segment membranes. Notably, the EP treatment maintained the natural color of the segments (∆E ≤ 2) and preserved more than 97% of the total soluble sugars. Furthermore, EP treatment exhibited greater advantages in preserving the major flavonoids without increasing the concentration of the bitter-causing compound, limonin. Conversely, CP treatment resulted in the decline of flavonoids. Hence, EP treatment had little effect on the physicochemical quality of citrus segments, which signifies its potential as a promising alternative to the traditional CP method for producing high-quality citrus segments.

Stabilization of Hydroxy-α-Sanshool by Antioxidants Present in the Genus Zanthoxylum.

Japanese pepper (sansho, Zanthoxylum piperitum) contains several types of sanshools belonging to N-alkylamides. Because of the long-chain unsaturated fatty acids present in their structure, sanshools are prone to oxidative deterioration, which poses problems in processing. In this paper, we evaluated the effects of antioxidants from the genus Zanthoxylum in preventing sanshool degradation using accelerated tests. An ethanolic extract of segment membranes of the sansho fruit pericarp was incubated at 70 °C for 7 days with different antioxidants to determine the residual amount of hydroxy-α-sanshool (HαS) in the extract. α-Tocopherol (α-Toc) showed excellent HαS-stabilizing activity at low concentrations. Among phenolic acids, we noted that the HαS-stabilizing activity increased with the number of hydroxy groups per molecule. For example, gallic acid and its derivatives exhibited excellent sanshool-stabilizing activity. Quercetin was found to be a superior HαS stabilizer compared with hesperetin and naringenin. However, the effective concentration was much higher for phenolic compounds than for α-Toc. These substances are believed to play a role in preventing the decomposition of sanshools in the pericarp of sansho. These sanshool stabilizers should be useful in the development of new beverages, foods, cosmetics, and pharmaceuticals that take advantage of the taste and flavor of sansho.

#3271 EXPRESSION OF THE COLLAGEN IV α345 MOLECULE ALONG THE RENAL TUBULE IN HEALTH AND DISEASE

Abstract Background and Aims Patients suffering from Alport Syndrome (AS) have a high life time risk of kidney failure and hearing loss. The underlying molecular cause is a germline mutation in one of the COL4A3/4/5 genes, whose gene products collectively form an important component of the glomerular basement membrane and the inner ear. Recent genetic studies have shown that the AS is much more prevalent than clinically recognized, suggesting that atypical clinical cases are frequent. Thus, patients with AS may phenocopy other kidney diseases. To date, pathomechanistic studies of the AS have focused exclusively on the glomerular membrane, yet equally strong expression of collagen IV can be found along the distal renal tubule. Structural disintegration of the distal tubular membrane may induce inflammation and fibrosis, thus progression of kidney disease. We hypothesize that genetic loss of the tubular collagen IV molecule contributes to kidney failure and may drive atypical phenotypes. Method Immunohistochemistry (IHC) and in situ hybridization (ISH, RNAscope) for COL IV α5, where IHC was performed on healthy human tissues as well as biopsies from patients with AS. Tubular marker staining for localization of COL IV α5 expression as well as spatial changes on consecutive sections. Human urinary primary tubular cells (huPTC) from healthy probands and patients with AS were generated and cultivated in cell culture, with analysis of COL IV mRNA by qPCR and detection of specifically expressed proteins by immunoblotting. Results COL IV α5 was detected within the tubular basement membrane (TBM) of the distal segments of renal tubules by IHC, including the thick ascending limb (TAL) of Henle (Tamm-Horsfall Protein), the distal convoluted tubule (11ß-Hydroxysteroid-Dehydrogenase) and the collecting duct (aquaporin 2). Spacial vicinity of these areas showed a predominance of interstitial fibrosis and inflammation in patient samples with AS, but not control samples with primary proteinuric diseases. Collagen IV protein is lost along the TBM of patients with AS, even in the hemizygous male and heterozygous female carriers of the hypomorphic but frequent COL4A5 mutation G624D. By ISH, COL4A5 expression was mainly observed in the glomerulus (most likely podocytes) and broadly in tubular epithelial cells, with only few tubulointerstitial cells showing mRNA expression. Likewise, the huPTC showed COL IV expression in qPCR, as well as COL IV α5 protein in immunoblotting. Conclusion Our studies show that the COL IV molecule is situated within the TBM of the complete distal tubule, starting from the TAL throughout the distant collecting duct. Although the epithelial cells have no detectable protein, in situ hybridization and primary cell cultures clearly suggest that tubular cells are a major source of the COL IV α345 molecule within the TBM. Renal biopsies of AS patients with diagnostic genetic COL IV variants indicate that tubulointerstitial fibrosis and inflammation starts in the vicinity of the distal tubule. Therefore, we postulate that the pathogenesis of AS may in part stem from the (distal) tubular apparatus, which is already known from other diseases such as ADTKD and nephronophthisis.

Identification of hub genes correlated with diabetic retinopathy via bioinformatics methods.

The aim of this study was to identify the hub genes and uncover the molecular mechanisms of diabetic retinopathy (DR). We used the Gene Expression Omnibus (GEO) dataset GSE60436 in our study. After screening for differentially expressed genes (DEGs), we performed gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) functional enrichment analysis. Subsequently, a protein-protein interaction (PPI) network was constructed using the Search Tool for Retrieval of Interacting Genes (STRING) database and visualized using the Cytoscape software. Finally, we identified 10 hub genes by cytoHubba plugin. A total of 592 DEGs were identified, including 203 up-regulated genes and 389 downregulated genes. The DEGs were mainly enriched in visual perception, photoreceptor outer segment membrane, retinal binding, and PI3K-Akt signaling pathway. By constructing a protein-protein interaction (PPI) network, 10 central genes were finally identified, including CNGA1, PDE6G, RHO, ABCA4, PDE6A, PDE6B, NRL, RPE65, GUCA1B and AIPL1. CNGA1, PDE6G, RHO, ABCA4, PDE6A, PDE6B, NRL, RPE65, GUCA1B, and AIPL1 may be potential biomarkers and therapeutic targets for DR.

P-Synephrine Indicates Internal Maturity of Citrus grandis (L.) Osbeck cv. Mato Peiyu-Reclaiming Functional Constituents from Nonedible Parts.

The processing of Citrus grandis Osbeck cv. Mato Peiyu (CGMP) fruits generates a considerable amount of waste, mainly the flavedo, albedo, and segment membrane; the generated waste yields severe environmental and economic challenges. In this study, we tried to reclaim some functional chemicals from the waste. Our data indicated that the essential oil content in the flavedo was 0.76-1.34%, with the major component being monoterpenes (93.75% in August, declining to 85.56% in November, including mainly limonene (87.08% to 81.12%) and others such as β-myrcene). p-Synephrine (mg/100 g dry weight) declined accordingly (flavedo, 10.40 to 2.00; albedo, 1.80 to 0.25; segment membrane, 0.3 in August, 0.2 in September, and none since October). Polyphenols (in μg/g) included gallic acid (70.32-110.25, 99.27-252.89, and 105.78-187.36, respectively); protocatechuic acid (65.32-204.94, 26.35-72.35, and 214.98-302.65, respectively), p-coumaric acid (30.63-169.13, 4.32-17.00, and 6.68-34.32, respectively), ferulic acid (12.36-39.36, 1.21-10.25, and 17.07-39.63, respectively), and chlorogenic acid (59.19-199.36, 33.08-108.57, and 65.32-150.14, respectively). Flavonoids (in μg/g) included naringin (flavedo, 89.32-283.19), quercetin (181.05-248.51), nobiletin (259.75-563.7), hesperidin, and diosmin. The phytosterol content (mg/100 g) was 12.50-44.00 in the flavedo. The total dietary fiber in the segment membrane was 57 g/100 g. The antioxidant activity against the DPPH• and ABTS+• free radicals was moderately high. In conclusion, the waste of CGMP fruits is worth reclaiming for essential oil, p-synephrine, polyphenolics, and dietary fiber. Notably, p-synephrine content (flavedo: <8 mg/100 g dry weight, albedo: <2.0, or segment membrane: <0.4 mg) can serve as a marker of the internal maturation of CGMP fruits.

ClC-K2 in the collecting duct intercalated cells contributes to blood pressure regulation during variations in dietary Cl-intake

Hypertension is the major clinically relevant problem affecting millions of people in the US. The renal collecting duct is known to play a critical role in setting salt-sensitivity of blood pressure. Originally, the majority of clinical and basic effort has been devoted to defining the detrimental roles of elevated dietary Na + in pathophysiology of hypertension. However, emerging evidence indicates that the dietary Cl - is as important for blood pressure control. The collecting duct has two independent types of cells: principal and intercalated having different functions and physiological roles. Principal cells regulate Na + reabsorption, whereas intercalated cells are responsible for transport of Cl - . ClC-K2 is a Cl - permeable channel abundantly expressed on the basolateral membrane of several distal nephron segments from the thick ascending limb to the collecting duct. Loss-of-function mutations in ClC-Kb (human orthologue of ClC-K2) cause Bartter’s syndrome type 3, which is associated with urinary salt wasting and hypotension. While the function of ClC-Kb in the thick ascending limb and distal convoluted tubule are thought to be responsible for the salt-wasting phenotype in patients with Bartter’s syndrome, the role of the channel in the collecting duct intercalated cells is not known. To address this critical gap, we compared the blood pressure phenotype and systemic Cl - balance in newly created mice with deletion of ClC-K2 in the renal nephron (RN-KO) and selectively in intercalated cells (IC-KO) using cre-loxP strategy. Since the commonly used Na + deficient diet only partially reduces chloride content and does not lead to appreciable reduction in blood pressure in rodents, we used the diet lacking both Na + and Cl - . As anticipated, RN-KO ClC-K2 mice had lower blood pressure on both regular and NaCl deficient diets when compared to the respective genetic controls (WT). In addition, the mutants exhibited larger urinary volume and Cl - wasting in response to dietary Cl - restriction. Importantly, IC-KO ClC-K2 mice had comparable blood pressure on regular diet, but became more hypotonic when compared to WT in response to dietary NaCl deficiency. Moreover, patch clamp studies in freshly isolated collecting ducts from WT mice revealed that ClC-K2 activity is proportionally increased to the amount of Cl - reduction in a diet suggesting that ClC-K2 is instrumental in augmenting Cl - reabsorption during Cl - deficiency.In conclusion, our results demonstrate, for the first time, the significance of ClC-K2 function in the collecting duct intercalated cells in setting salt sensitivity of blood pressure. This research was supported by NIH-NIDDK DK117865, DK119170, AHA EIA35260097 (to O. Pochynyuk) and AHA-19CDA34660148 (to V. N. Tomilin). This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Safety evaluation and whole genome sequencing for revealing the ability of Penicillium oxalicum WX-209 to safely and effectively degrade citrus segments

The microbial potential of Penicillium has received critical attention. The present research aimed to elucidate the efficacy of crude enzyme secreted from Penicillium oxalicum WX-209 in degrading citrus segments and evaluate the safety of the process. Results showed that citrus segment membranes gradually dissolved after treatment with the crude enzyme solution, indicating good degradation capability. No significant differences in body weight, food ingestion rate, hematology, blood biochemistry, and weight changes of different organs were found between the enzyme intake and control groups. Serial experiments showed that the crude enzyme had high biological safety. Moreover, the whole genome of P. oxalicum WX-209 was sequenced by PacBio and Illumina platforms. Twenty-five scaffolds were assembled to generate 36 Mbp size of genome sequence comprising 11 369 predicted genes modeled with a GC content of 48.33 %. A total of 592 genes were annotated to encode enzymes related to carbohydrates, and some degradation enzyme genes were identified in strain P. oxalicum WX-209. Data availabilityThe whole genome sequencing data in this study can be found in GenBank database of NCBI website with the accession number PRJNA 715321. The link: http://www.ncbi.nlm.nih.gov/bioproject/715321.

Agronomic Practices Alter Regulated Effects of Easily Extractable Glomalin-Related Soil Protein on Fruit Quality and Soil Properties of Satsuma Mandarin

Easily extractable glomalin-related soil protein (EEG) released from arbuscular mycorrhizal fungi exhibits many roles in soil and plants, while it is not clear whether the biostimulator alone or in combination with agronomic practices can improve soil characteristics and fruit quality in citrus. The objective of this study was to analyze the effects of foliar sprays of EEG, singly or in combination with fruit bagging (FB), reflective film mulching (RF), and grass-proof cloth mulching (GPC) on root mycorrhizal colonization rate, fruit internal and external quality, and soil structure and fertility on an early-ripening Satsuma mandarin “Oita 4” (Citrus unshiu cv. Oita 4). Exogenous EEG application increased root mycorrhizal colonization, while agronomic practices dramatically inhibited root mycorrhizal colonization in EEG-treated trees. Foliar EEG application significantly improved the internal and external quality of fruits, but the combination of three agronomic practices with EEG did not further enlarge the improved effect on the external quality of fruit and even produced an inhibitory effect. Also, the addition of RF further amplified the improved effect of EEG on the contents of fruit vitamin C and soluble solids. EEG application also significantly elevated sucrose in the fruit pith and juice sac, fructose in the fruit peel, fruit pith, segment membrane, and juice sac, and glucose in the fruit pith, segment membrane, and juice sac. Additional RF treatment could increase sucrose in the fruit peel and juice sac as well as glucose in the fruit peel to varying degrees in EEG-treated trees. EEG application also significantly increased soil organic carbon, mean weight diameter, nitrate nitrogen, ammonium nitrogen, available phosphorus, and available potassium levels, with additional agronomic practices almost reducing the promoting effect of EEG on these soil variables. It has been summarized that a single EEG application had positive effects on fruit quality and soil fertility, while the additional agronomic practices resulted in little change or even suppressed the positive effects of EEG.

Spatiotemporal Live-Cell Analysis of Photoreceptor Outer Segment Membrane Ingestion by the Retinal Pigment Epithelium Reveals Actin-Regulated Scission.

The photoreceptor outer segment (OS) is the phototransductive organelle in the vertebrate retina. OS tips are regularly ingested and degraded by the adjacent retinal pigment epithelium (RPE), offsetting the addition of new disk membrane at the base of the OS. This catabolic role of the RPE is essential for photoreceptor health, with defects in ingestion or degradation underlying different forms of retinal degeneration and blindness. Although proteins required for OS tip ingestion have been identified, spatiotemporal analysis of the ingestion process in live RPE cells is lacking; hence, the literature reflects no common understanding of the cellular mechanisms that affect ingestion. We imaged live RPE cells from mice (both sexes) to elucidate the ingestion events in real time. Our imaging revealed roles for f-actin dynamics and specific dynamic localizations of two BAR (Bin-Amphiphysin-Rvs) proteins, FBP17 and AMPH1-BAR, in shaping the RPE apical membrane as it surrounds the OS tip. Completion of ingestion was observed to occur by scission of the OS tip from the remainder of the OS, with a transient concentration of f-actin forming around the site of imminent scission. Actin dynamics were also required for regulating the size of the ingested OS tip, and the time course of the overall ingestion process. The size of the ingested tip is consistent with the term "phagocytosis." However, phagocytosis usually refers to engulfment of an entire particle or cell, whereas our observations of OS tip scission indicate a process that is more specifically described as "trogocytosis," in which one cell "nibbles" another cell.SIGNIFICANCE STATEMENT The ingestion of the photoreceptor outer segment (OS) tips by the retinal pigment epithelium (RPE) is a dynamic cellular process that has fascinated scientists for 60 years. Yet its molecular mechanisms had not been addressed in living cells. We developed a live-cell imaging approach to investigate OS tip ingestion, and focused on the dynamic participation of actin filaments and membrane-shaping BAR proteins. We observed scission of OS tips for the first time, and were able to monitor local changes in protein concentration preceding, during, and following scission. Our approach revealed that actin filaments were concentrated at the site of OS scission and were required for regulating the size of the ingested OS tip and the time course of the ingestion process.

Citrus × paradisi L. Fruit Waste: The Impact of Eco-Friendly Extraction Techniques on the Phytochemical and Antioxidant Potential

Citrus fruits have been the subject of extensive research over the years due to their impressive antioxidant properties, the health benefits of flavanones, and their potential use in the prevention and treatment of chronic diseases. Grapefruit have been shown in studies to improve overall health, with numerous potential benefits, including improved heart health, reduced risk of certain cancers, improved digestive health, and improved immune system function. The development of cyclodextrin complexes is an exciting approach to increasing the content of flavanones such as naringin and naringenin in the extraction medium while improving the profile of beneficial phenolic compounds and the antioxidant profile. This research aims to optimize the extraction conditions of the flavanones naringin and naringenin with additional compounds to increase their yield from different parts of grapefruit (Citrus × paradisi L.) fruits, such as albedo and segmental membranes. In addition, the total content of phenolic compounds, flavonoids, and the antioxidant activity of ethanolic extracts produced conventionally and with -cyclodextrin was examined and compared. In addition, antioxidant activity was measured using the radical scavenging activity assay (ABTS), radical scavenging activity assay (DPPH), and ferric reducing antioxidant power (FRAP) methods. The yield of naringin increased from 10.53 ± 0.52 mg/g to 45.56 ± 5.06 mg/g to 51.11 ± 7.63 mg/g of the segmental membrane when cyclodextrins (α, β-CD) were used; naringenin increased from 65.85 ± 10.96 μg/g to 91.19 ± 15.19 μg/g of the segmental membrane when cyclodextrins (α, β-CD) were used. Furthermore, the results showed that cyclodextrin-assisted extraction had a significant impact in significantly increasing the yield of flavanones from grapefruit. In addition, the process was more efficient and less expensive, resulting in higher yields of flavanones with a lower concentration of ethanol and effort. This shows that cyclodextrin-assisted extraction is an excellent method for extracting valuable compounds from grapefruit.

Fan-noise reduction of data centre telecommunications’ server racks, with an acoustic metamaterial broadband, low-frequency sound-absorbing liner

An acoustic metamaterial is evaluated successfully as a means to reduce axial fan noise in an IT server rack application. The continuing growth in demand for cloud-based memory storage is outpacing sustainable energy management which still requires the axial fan as a fundamental component in temperature control technologies. As chip temperatures increase, additional numbers of more powerful fans are required to run faster with the result that data centres have become unsafe working environments due to the acoustic output exceeding prescribed occupational noise level limits. Noise isolation using soundproof cabinets is expensive and impractical in data centres which seek to reduce floor space and communication losses. Instead, in this work, a 15 mm deep acoustic liner solution is proposed being the approach taken in the aeronautics sector to reduce aeroengine noise which, similarly, is a flow duct problem. The acoustic metamaterial adopted here is the recently developed Segmented Membrane Sound Absorber (SeMSA) which can be tailored for low frequency, broadband and tonal noise in a thin form-factor and which can be used in a grazing flow configuration. An equivalent circuit model developed for the SeMSA allows its design to be optimised to attenuate a typical server fan’s frequency spectrum. An array of manufactured rectangular SeMSA cells was embedded in a “deflector plate”, which is an existing component in a server rack. The deflector plate was implemented in a custom-built fan sound power rig, tested in an hemi-anechoic chamber and compared to a hardwall case and to PU foam. A relative overall decrease of 2.5 dBA was achieved for the SeMSA deflector plate liner which corresponds to a 43.9% decrease in overall sound emissions, which using a material thickness of only 15 mm, signifies an almost twofold increase in the time required for hearing damage to occur. A 3 dBA drop was achieved at the blade passing frequency of 620 Hz, while relative drops of 1–2.5 dBA were achieved from 2000–8000 Hz.

Modus operandi of ClC-K2 Cl- Channel in the Collecting Duct Intercalated Cells.

The renal collecting duct is known to play a critical role in many physiological processes, including systemic water-electrolyte homeostasis, acid-base balance, and the salt sensitivity of blood pressure. ClC-K2 (ClC-Kb in humans) is a Cl--permeable channel expressed on the basolateral membrane of several segments of the renal tubule, including the collecting duct intercalated cells. ClC-Kb mutations are causative for Bartters' syndrome type 3 manifested as hypotension, urinary salt wasting, and metabolic alkalosis. However, little is known about the significance of the channel in the collecting duct with respect to the normal physiology and pathology of Bartters' syndrome. In this review, we summarize the available experimental evidence about the signaling determinants of ClC-K2 function and the regulation by systemic and local factors as well as critically discuss the recent advances in understanding the collecting-duct-specific roles of ClC-K2 in adaptations to changes in dietary Cl- intake and maintaining systemic acid-base homeostasis.

Molecular insights into endolysosomal microcompartment formation and maintenance.

The endolysosomal system of eukaryotic cellshas a key role in the homeostasis of the plasma membrane, in signaling and nutrient uptake, and is abused by viruses and pathogens for entry. Endocytosis ofplasma membrane proteins results in vesicles, which fuse with the early endosome. If destined for lysosomal degradation, these proteins are packaged into intraluminal vesicles, converting an early endosome to a late endosome, which finally fuses with the lysosome. Each ofthese organelles has a unique membrane surface composition, which can form segmented membrane microcompartments by membrane contact sites or fission proteins. Furthermore, these organelles are in continuous exchange due to fission and fusion events. The underlying machinery, which maintains organelle identity along thepathway, is regulated by signaling processes. Here, we will focus on the Rab5 and Rab7 GTPases of early and late endosomes. As molecular switches, Rabs depend on activating guanine nucleotide exchange factors (GEFs). Over the last years, we characterized the Rab7 GEF, the Mon1-Ccz1 (MC1) complex, and key Rab7 effectors, the HOPS complex and retromer. Structural and functional analyses of these complexes lead to a molecular understanding of their function in the context of organelle biogenesis.

Naringinase Biosynthesis by Aspergillus niger on an Optimized Medium Containing Red Grapefruit Albedo.

This study aimed to develop a method of naringinase biosynthesis by Aspergillus niger KMS on an optimized culture medium. The concentration of the six medium components in shake flasks was optimized by the Box and Wilson factor gradient method. Naringinase's substrate, naringin, powdered albedo, flavedo, and red grapefruit segment membranes were used to stimulate naringinase biosynthesis. Rhamnose was chosen as the carbon source, while the nitrogen source was yeast extract and sodium nitrate. Naringinase biosynthesis was most favorable in the culture medium with the following composition (g 100 mL): 3.332-NaNO3; 3.427-yeast extract; 0.184-KH2PO4; 0.855-red grapefruit albedo; 0.168-naringin; 2.789-rhamnose. The obtained Aspergillus niger KMS culture fluid was concentrated, thereby precipitating the protein. As a result, a naringinase preparation with high activity, equal to 816 µmol × min-1 × g-1, was obtained.