Maintaining Cell Membrane Integrity Research Articles

Lysophospholipid acyltransferase-mediated formation of saturated glycerophospholipids maintained cell membrane integrity for hypoxic adaptation.

Adaptation to hypoxia has attracted much public interest because of its clinical significance. However, hypoxic adaptation in the body is complicated and difficult to fully explore. To explore previously unknown conserved mechanisms and key proteins involved in hypoxic adaptation in different species, we first used a yeast model for mechanistic screening. Further multi-omics analyses in multiple species including yeast, zebrafish and mice revealed that glycerophospholipid metabolism was significantly involved in hypoxic adaptation with up-regulation of lysophospholipid acyltransferase (ALE1) in yeast, a key protein for the formation of dipalmitoyl phosphatidylcholine [DPPC (16:0/16:0)], which is a saturated phosphatidylcholine. Importantly, a mammalian homolog of ALE1, lysophosphatidylcholine acyltransferase 1 (LPCAT1), enhanced DPPC levels at the cell membrane and exhibited the same protective effect in mammalian cells under hypoxic conditions. DPPC supplementation effectively attenuated growth restriction, maintained cell membrane integrity and increased the expression of epidermal growth factor receptor under hypoxic conditions, but unsaturated phosphatidylcholine did not. In agreement with these findings, DPPC treatment could also repair hypoxic injury of intestinal mucosa in mice. Taken together, ALE1/LPCAT1-mediated DPPC formation, a key pathway of glycerophospholipid metabolism, is crucial for cell viability under hypoxic conditions. Moreover, we found that ALE1 was also involved in glycolysis to maintain sufficient survival conditions for yeast. The present study offers a novel approach to understanding lipid metabolism under hypoxia and provides new insights into treating hypoxia-related diseases.

Physiological Regulation of Photosynthetic-Related Indices, Antioxidant Defense, and Proline Anabolism on Drought Tolerance of Wild Soybean (Glycine soja L.)

Wild soybean (Glycine soja L.), drought-tolerant cultivar Tiefeng 31 (Glycine max L.), and drought-sensitive cultivar Fendou 93 (Glycine max L.) were used as materials to investigate the drought tolerance mechanism after 72 h 2.5 M PEG 8000 (osmotic potential −0.54 MPa)-simulated drought stress at the seedling stage. The results indicated that the leaves of the G. soja did not wilt under drought stress. However, both the drought-tolerant and drought-sensitive cultivated soybean cultivars experienced varying degrees of leaf wilt. Notably, the drought-sensitive cultivated soybean cultivars exhibited severe leaf wilt after the drought stress. Drought stress was determined to have a significant impact on the dry matter of the above-ground part of the drought-sensitive cultivar Fendou 93, followed by the drought-tolerant cultivar Tiefeng 31, with the lowest reduction observed in G. soja. Furthermore, the presence of drought stress resulted in the closure of leaf stomata. G. soja exhibited the highest proportion of stomatal opening per unit area, followed by the drought-tolerant cultivar Tiefeng 31, while the drought-sensitive cultivar Fendou 93 displayed the lowest percentage. Photosynthesis-related indexes, including photosynthetic rate, intercellular CO2, transpiration rate, and stomatal conductance, decreased in Fendou 93 and Tiefeng 31 after drought stress, but increased in G. soja. In terms of the antioxidant scavenging system, lower accumulation of malondialdehyde (MDA) was observed in G. soja and Tiefeng 31, along with higher activities of superoxide dismutase (SOD, EC 1.15.1.1) and catalase (CAT, EC 1.11.1.6) to counteract excess reactive oxygen species and maintain cell membrane integrity. In contrast, the drought-sensitive cultivar Fendou 93 had higher MDA content and higher activities of ascorbate peroxidase (APX, EC 1.11.1.11) and peroxidase (POD, 1.11.1.7). G. soja and Tiefeng 31 also exhibited less accumulation of osmolytes, including soluble sugar, soluble protein, and free proline content. The activities of δ-OAT, ProDH, and P5CS, key enzymes in proline anabolism, showed an initial increase under drought stress, followed by a decrease, and then an increase again at the end of drought stress in G. soja. Before drought stress, Tiefeng 31 had higher activities of ProDH and P5CS, which decreased with prolonged drought stress. Fendou 93 experienced an increase in the activities of δ-OAT, ProDH, and P5CS under drought stress. The δ-OAT gene expression levels were up-regulated in all three germplasms. The expression levels of the P5CS gene in Fendou 93 and Tiefeng 31 were down-regulated, while G. soja showed no significant change. The expression of the P5CR gene and ProDH gene was down-regulated in Fendou 93 and Tiefeng 31, but up-regulated in G. soja. This indicates that proline content is regulated at both the transcription and translation levels.

GP-fatty acid axis regulating the adaptive morphogenesis of VBNC bacteria in response to chlorine stress in the process of chlorination disinfection

Investigating the specific metabolic regulatory strategy of viable but non-culturable (VBNC) bacteria is crucial for understanding adaptive morphogenesis, processes of shrinking body size and maintaining cell membrane integrity. Metabolomic studies have revealed an upregulation in the metabolic competence of glycerophospholipids (GP) and fatty acid catabolism in VBNC bacteria. Disruption of the GP-fatty acid axis, as evidenced by scanning electron microscopy, hinders the maintenance of adaptive morphology. VBNC bacteria minimize cell size by consuming fatty acids to sustain intracellular energy metabolism. Concurrently, GP metabolism replenishes fatty acid consumption and upholds cell membrane integrity, preventing HClO intrusion. Regulation of the GP-fatty acid axis also sustains intracellular antioxidants (e.g. glutathione and ubiquinone), preventing lipid peroxidation. Moreover, disruption of the GP-fatty acid axis impedes biofilm formation (reduced by 94.77 %) and reactivation (reduced by 95.73 %) of VBNC bacteria, with negligible effects on culturable bacteria. The study underscores the GP-fatty acid axis regulation to form adaptive morphology is a fundamental survival strategy for VBNC bacteria. Developing an efficient disinfection method targeting the GP-fatty acid axis emerges as a promising strategy to mitigate the health risk of VBNC bacteria.

Enhanced shelf life quality of peaches (Prunus persica L.) using ethylene manipulating active packaging in e-commerce logistics

Ethylene manipulating active packaging can effectively maintain the quality of peaches during storage. To explore the effectiveness of ethylene manipulating active packaging during E-commerce logistics, 1-methylcyclopropene (1-MCP) paper cards and ethylene absorbent (EA) sachets were applied to the peaches. During the logistics process, the ambient temperature and the vibration intensity inside the packaging remain at a high level and fluctuates greatly. In comparison with the control group, 1-MCP and EA significantly reduced the respiration rate, delayed ethylene release, and maintained the firmness and volatile compounds in peaches under high temperature and vibration stress. Five days after storage, the peel firmness, flesh firmness, cohesiveness, and chewiness of 1-MCP treatment decreased by 0.15 N, 6.37 N, 0.10 and 0.78, respectively. The total lactone content of peaches in control group reached 3.79 % at 10th day of storage, which was 2.61 % and 2.44 % higher than 1-MCP and EA group respectively. Furthermore, 1-MCP and EA can inhibited the accumulation of MDA and maintained cell membrane integrity. Among them, 1-MCP was more effective than EA. In conclusion, peaches treated with 1-MCP paper cards during E-commerce logistics can maintain good quality and extend shelf life. Our results confirmed that ethylene manipulating active packaging could effectively prolong the shelf life of peaches during E-commerce logistics.

CHMP4B and VSP4A reverse GSDMD-mediated pyroptosis by cell membrane remodeling in endometrial carcinoma

BackgroundIn advanced and recurrent endometrial carcinoma (EC), the current state of immuno- or targeted therapy remains in the clinical research phase. Our study aimed to explore the role of the ESCRT machinery in maintaining cell membrane integrity and reversing pyroptotic cell death. MethodsImmunohistochemistry, western blotting, and co-immunoprecipitation were performed to determine the expression and relationship between GSDMD, CHMP4B, and VPS4A. We employed techniques such as FITC Annexin V/propidium iodide staining, Ca2+ fluorescence intensity, IL-1β enzyme-linked immunosorbent assay, and lactate dehydrogenase release assay to detect pyroptosis in endometrial cancer cells. Plasma membrane perforations and CHMP4B/VPS4A puncta were observed through electron and fluorescence confocal microscopy. ResultsWe showed that GSDMD, CHMP4B, and VPS4A were differentially expressed in the pyroptotic EC xenograft mouse model group, as well as high, moderate, and mild expression in EC cells treated with LPS and nigericin compared to endometrial epithelial cells. Co-IP confirmed the interaction between GSDMD, CHMP4B, and VPS4A. We found that GSDMD knockdown reduced PI-positive cells, Ca2+ efflux, IL-1β, and LDH release, while CHMP4B and VPS4A depletion enhanced these indicators in HEC1A and AN3CA cells. Electron microscopy showed membrane perforations correspondingly decreased with inactivated GSDMD and increased or decreased after CHMP4B and VPS4A depletion or overexpression in EC cells. Fluorescence confocal microscopy detected CHMP4B protein puncta associated with VPS4A at the injured plasma membrane in GSDMDNT cells. ConclusionsWe preliminary evidenced that CHMP4B and VPS4A reverses GSDMD-mediated pyroptosis by facilitating cell membrane remodeling in endometrial carcinoma. Targeting CHMP4B related proteins may promote pyroptosis in endometrial tumors.

Development of composite film based on polyvinyl alcohol with binary nanoreinforcements for active packaging of fresh-cut apples

To develop a sustainable and environmentally-friendly preservation packaging for fresh-cut fruits and vegetables (FFV), this study synthesized the nanohybrid LDH@PCA using layered double hydroxide (LDH) loaded with p-coumaric acid (PCA). Subsequently, the nanohybrid and lignin nanoparticles (LPs) were integrated into a polyvinyl alcohol (PVA) matrix to prepare a binary nanocomposite packaging material named PVA-LPs-LDH@PCA. In this case, LDH@PCA and LPs were homogeneously dispersed inside PVA, relying on hydrogen bonding at 3 % (w/w) and 5 % (w/w), respectively, while electrostatic attraction also played a role. The reinforcement of the binary nanomaterials led to a significant increase in the radius of gyration and mass fractal dimension of the microregions within the PVA films. Additionally, the tensile strengths were 66 %, 32 %, and 8 % higher than those of the PVA, PVA-LPs, and PVA-LDH@PCA films, respectively. Moreover, the binary nanocomposite packaging exhibited enhanced water vapor, oxygen, UV barrier, and thermal stability, while synergistically improving its antioxidant activity compared to the aforementioned films. Remarkably, PCA in PVA-LPs-LDH@PCA demonstrated sustained release properties, consistent with Avrami and Arabolic diffusion models, for up to 55 h. Packaging of fresh-cut apples with PVA-LPs-LDH@PCA effectively maintained the texture, appearance, and nutritional quality. Transcriptomic and metabolomic analyses revealed that this packaging inhibited cell wall degradation, maintained cell membrane integrity, stimulated scavenging of reactive oxygen species, and inhibited polyphenol oxidase, attenuating the adverse effects of water loss stress on fresh-cut apples. These findings suggest that PVA binary nanocomposite films hold great potential as a sustainable solution for freshness preservation in FFV packaging.

Lactobacillus plantarum AR113 attenuates liver injury in D-galactose-induced aging mice via the inhibition of oxidative stress and endoplasmic reticulum stress

Probiotics could effectively eliminate excess reactive oxygen species (ROS) generated during aging or lipid metabolism disorders, but their mechanism is unclear. The major purpose of this study was to investigate the mechanism of Lactiplantibacillus plantarun AR113 alleviating oxidative stress injury in the D-galactose induced aging mice. The result showed that pretreatment with L. plantarun AR113 significantly relieving H2O2 induced cytotoxicity in HepG2 cells by maintain cell membrane integrity and increasing antioxidant enzyme activities. In D-galactose induced aging mice, L. plantarun AR113 could significantly attenuate liver damage and inflammatory infiltration by promoting endogenous glutathione (GSH) synthesis and activating the Nrf2/Keap1 signaling pathway in mice, and increasing the expression of regulated phase II detoxification enzymes and antioxidant enzymes. Further analysis shown that gavage of L. plantarun AR113 could significantly reduce the expression of G protein-coupled receptor 78 (GPR78) and C/EBP homologous protein (CHOP) proteins, and promote the restoration of endoplasmic reticulum (ER) homeostasis, thereby activating cell anti-apoptotic pathways. These results were also confirmed in H2O2-treated HepG2 experiments. It indicated that L. plantarun AR113 could inhibit D-galactose-induced liver injury through dual inhibition of ER stress and oxidative stress. L. plantarun AR113 have good application potential in anti-aging and alleviating metabolic disorders.

Biochemistry behind firmness retention of jujube fruit by combined treatment of acidic electrolyzed water and high-voltage electrostatic field.

Harvested jujube (Zizyphus jujuba Mill) is prone to softening due to active metabolism. This study investigated the effects of acidic electrolyzed water (AEW), high-voltage electrostatic field (HVEF) and their combination (AEW+HVEF) on softening and associated cell wall degrading enzymes (CWDEs), cell membrane integrity and antioxidant system of 'Huping' jujube during storage at 0±1°C. The results indicated that fruit subjected to AEW+HVEF, AEW or HVEF treatments maintained firmness 15.7%, 10.7%, and 5.3% higher than that of untreated control fruit at the end of 90days cool storage. Fruit treated with AEW+HVEF could better maintain cell membrane integrity and exhibit lower activities of CWDEs and higher antioxidant capacity than that treated with either AEW or HVEF. Correlation analysis suggested that inhibition of softening was associated with reduction of CWDEs activities, and maintenance of membrane integrity and antioxidant system.

CHMP4B and VSP4A reverse GSDMD-mediated pyroptosis by cell membrane remodeling in endometrial carcinoma

BackgroundIn advanced and recurrent endometrial carcinoma (EC), the current state of immuno- or targeted therapy remains in the clinical research phase. Our study aimed to explore the role of the ESCRT machinery in maintaining cell membrane integrity and reversing pyroptotic cell death. MethodsImmunohistochemistry, western blotting, and co-immunoprecipitation were performed to determine the expression and relationship between GSDMD, CHMP4B, and VPS4A. We employed techniques such as FITC Annexin V/propidium iodide staining, Ca2+ fluorescence intensity, IL-1β enzyme-linked immunosorbent assay, and lactate dehydrogenase release assay to detect pyroptosis in endometrial cancer cells. Plasma membrane perforations and CHMP4B/VPS4A puncta were observed through electron and fluorescence confocal microscopy. ResultsWe showed that GSDMD, CHMP4B, and VPS4A were differentially expressed in the pyroptotic EC xenograft mouse model group, as well as high, moderate, and mild expression in EC cells treated with LPS and nigericin compared to endometrial epithelial cells. Co-IP confirmed the interaction between GSDMD, CHMP4B, and VPS4A. We found that GSDMD knockdown reduced PI-positive cells, Ca2+ efflux, IL-1β, and LDH release, while CHMP4B and VPS4A depletion enhanced these indicators in HEC1A and AN3CA cells. Electron microscopy showed membrane perforations correspondingly decreased with inactivated GSDMD and increased or decreased after CHMP4B and VPS4A depletion or overexpression in EC cells. Fluorescence confocal microscopy detected CHMP4B protein puncta associated with VPS4A at the injured plasma membrane in GSDMDNT cells. ConclusionsWe preliminary evidenced that CHMP4B and VPS4A reverses GSDMD-mediated pyroptosis by facilitating cell membrane remodeling in endometrial carcinoma. Targeting CHMP4B related proteins may promote pyroptosis in endometrial tumors.

Temperature-induced lipocalin-mediated membrane integrity: Possible implications for vindoline accumulation in Catharanthus roseus leaves.

Plant lipocalins perform diverse functions. Recently, allene oxide cyclase, a lipocalin family member, has been shown to co-express with vindoline pathway genes in Catharanthus roseus under various biotic/abiotic stresses. This brought focus to another family member, a temperature-induced lipocalin (CrTIL), which was selected for full-length cloning, tissue-specific expression profiling, in silico characterization, and upstream genomic region analysis for cis-regulatory elements. Stress-mediated variations in CrTIL expression were reflected as disturbances in cell membrane integrity, assayed through measurement of electrolyte leakage and lipid peroxidation product, MDA, which implicated the role of CrTIL in maintaining cell membrane integrity. For ascertaining the function of CrTIL in maintaining membrane stability and elucidating the relationship between CrTIL expression and vindoline content, if any, a direct approach was adopted, whereby CrTIL was transiently silenced and overexpressed in C. roseus. CrTIL silencing and overexpression confirmed its role in the maintenance of membrane integrity and indicated an inverse relationship of its expression with vindoline content. GFP fusion-based subcellular localization indicated membrane localization of CrTIL, which was in agreement with its role in maintaining membrane integrity. Altogether, the role of CrTIL in maintaining membrane structure has possible implications for the intracellular sequestration, storage, and viability of vindoline.

BHTCM Protects Müller Cells from Diabetic Retinopathy by Reducing Abnormal Changes of Kir4.1 and AQP4, Suppressing VEGF and IL-1β, and Enhancing PEDF Production

Background: In the diabetic condition, damage to the Müller cells contributes to the pathogenesis of diabetic retinopathy. Aims: This study aimed to investigate the protective effect of Bushen Huoxue, Traditional Chinese Medicine (BHTCM), on Müller in diabetic retinopathological conditions. Methods: Primary rat retinal Müller cells (RRMC) were isolated and cultured under high glucose (50 nmol/L). The advanced glycation end products (AGEs) and sodium dithionite were applied to treat highglucose administrated RRMC to mimic diabetic retinopathological conditions. The effects of BHTCM on diabetic retinopathological RRMC were evaluated. The expressions of aquaporin-4 (AQP4) and Kir4.1 were determined by double-labeling immunofluorescence and ELISA. Levels of vascular endothelial growth factor (VEGF), interleukin-1β (IL-1β) and pigment epithelium-derived factor (PEDF) were examined with ELISA. Lactate dehydrogenase (LDH) activity was also evaluated. Results: Retinal Müller cells were successfully isolated and identified. RRMC treated with AGEs and sodium dithionite resulted in the increase of AQP4 and decrease of Kir4.1 in RRMC, increase of VEGF and IL-1β secretion, increase of LDH activity, decrease of PEDF secretion in culture medium, all of which, in a dose-dependent or time-dependent manner. Post treating RRMC with AGEs and dithionite, BHTCM reversed changes in expression of AQP4 and Kir4.1 in RRMC, and reversed VEGF levels, PEDF and IL-1β secretion in the culture medium. Moreover, BHTCM reversed the decrease of RRMC cell membrane integrity after AGEs and dithionite treatment. Conclusions: BHTCM protected Müller cells from diabetic damage by reducing abnormal changes of Kir4.1 and AQP4, inhibiting VEGF and IL-1β, increasing PEDF production, and maintaining cell membrane integrity. Therefore, BHTCM is a potential drug for the treatment of diabetic retinopathy, which can correct the function of Müller cells.

Chitosan and chitooligosaccharide regulated reactive oxygen species homeostasis at wounds of pear fruit during healing

Both chitosan (CTS) and chitooligosaccharide (COS) can promote fruit healing. However, whether the two chemicals regulate reactive oxygen species (ROS) homeostasis during wound healing of pear fruit remains unknown. In this study, the wounded pear fruit (Pyrus bretschneideri cv. Dongguo) was treated with a 1 g L−1 CTS and COS. We found CTS and COS treatments increased NADPH oxidase and superoxide dismutase activities, and promoted O2.- and H2O2 production at wounds. CTS and COS also enhanced the activities of catalase, peroxidase, ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, and glutathione reductase, and elevated the levels of ascorbic acid and glutathione. In addition, the two chemicals improved antioxidant capacity in vitro and maintained cell membrane integrity at fruit wounds during healing. Taken together, CTS and COS can regulate ROS homeostasis at wounds of pear fruit during healing by scavenging excessive H2O2 and improving antioxidant capacity. Overall, the COS demonstrated superior performance over the CTS.

Ram sperm cryopreservation disrupts metabolism of unsaturated fatty acids

In ram sperm, metabolites are important components of the plasma membrane, energy metabolism cycle, and precursors for other membrane lipids, and they may have important roles in maintaining plasma membrane integrity, energy metabolism, and regulation of cryotolerance. In this study, the ejaculates from 6 Dorper rams were pooled and sperm were systematically investigated by metabolomics at various steps of cryopreservation (37 °C, fresh [F]; from 37 to 4 °C, cooling [C]; and from 4 to −196 to 37 °C, frozen-thawed [FT]) to identify differential metabolites (DM). There were 310 metabolites identified, of which 86 were considered DMs. Regarding the DMs, there were 23 (0 up and 23 down), 25 (12 up and 13 down), and 38 (7 up and 31 down) identified during cooling (C vs F), freezing (FT vs C), and cryopreservation (FT vs F), respectively. Furthermore, some key polyunsaturated fatty acids (FAs), particularly, linoleic acid (LA), docosahexaenoic acid (DHA), and arachidonic acid (AA) were down-regulated during cooling and cryopreservation. Significant DMs were enriched in several metabolic pathways including biosynthesis of unsaturated FAs, LA metabolism, mammalian target of rapamycin (mTOR), forkhead box transcription factors (FoxO), adenosine monophosphate-activated protein kinase (AMPK), phosphatidylinositol 3-kinase/protein kinase B (PI3K-Akt) signaling pathways, regulation of lipolysis in adipocytes, and FA biosynthesis. This was apparently the first report to compare metabolomics profiles of ram sperm during cryopreservation and provided new knowledge to improve this process.

UV-C irradiation maintains cell membrane integrity at wounds of potato tubers during healing by regulating ROS homeostasis and increasing antioxidant activity

Ultraviolet-C (UV-C), a short-wave ultraviolet light, has been extensively proved to regulate reactive oxygen species (ROS) homeostasis and increase antioxidant activity in fruit and vegetables. However, whether UV-C may regulate ROS homeostasis, antioxidant activity and cell membrane integrity at potato tubers wounds during healing has not been reported. In this study, UV-C irradiation activated calcium-dependent protein kinase (CDPK), NADPH oxidase (NOX) and superoxide dismutase (SOD), and promoted superoxide anion (O2.-) and hydrogen peroxide (H2O2) production at tuber wounds. Meanwhile, UV-C activated catalase (CAT), peroxidase (POD), ascorbate peroxidase (APX) and glutathione reductase (GR), and elevated the levels of ascorbic acid (AsA), reduced glutathione (GSH), total phenolic and flavonoid at tuber wounds. Furthermore, UV-C decreased malondialdehyde (MDA) content and cell membrane permeability at tuber wounds by enhancing the scavenging capacities of DPPH, ABTS+ and FRAP. Taken together, UV-C irradiation could maintain cell membrane integrity at potato tubers wounds during healing by regulating ROS homeostasis and increasing antioxidant activity.

Castor bean cake increases osmoprotection and oil production in basil (Ocimum basilicum) under saline stress

Water salinity is a major abiotic stress that impacts plant growth and metabolism, reducing crop production. However, the adequate use of organic fertilizers rich in nitrogen (N) can attenuate the damages caused by saline stress. In this context, the castor bean cake (CBC), a co-product of the castor oil production chain, has shown great potential as organic fertilizer and stress mitigator, however, the mechanisms involved in these responses remain unclear. Thus, this study aimed to investigate the effects of different doses of CBC and electrical conductivities of irrigation water (EC) on the photochemical efficiency of photosystem II, the accumulation of organic solutes, and the oil production in basil. The experimental design was randomized blocks in a 5 × 5 factorial scheme, combining levels of EC (0.5, 1.2, 3.0, 4.7, 5.5 dS m−1) with doses of CBC (0.0, 1.4, 5.0, 8.5 and 10 t ha−1), in a matrix generated by the Box Central Compound. The contents of proline, glycine-betaine, proteins, amino acids, reducing sugars, non-reducing sugars, total sugars, photosynthetic pigments, electrolyte leakage, chlorophyll a fluorescence, and oil production were evaluated. The highest photochemical efficiency and oil content was found in basil irrigated with EC up to 3 dS m−1 and supplemented with 5 t ha−1 of CBC, which was followed by lower electrolyte leakage. In addition, CBC induced osmoregulation under saline conditions, as shown by the increase in free amino acids, proteins, proline, glycine-betaine, and sugars. However, high doses of CBC combined with high EC reduced photosynthetic pigment content, chlorophyll a fluorescence, and oil content. In conclusion, CBC induced osmoprotection, maintaining cell membrane integrity and increasing photochemical efficiency of basil. In addition, the use of 5 t ha−1 of CBC combined with low levels of water salinity can be employed to enhance oil production in basil.

Enhancement of the Expression of ZmBZR1 and ZmBES1 Regulatory Genes and Antioxidant Defense Genes Triggers Water Stress Mitigation in Maize (Zea mays L.) Plants Treated with 24-Epibrassinolide in Combination with Spermine

Water shortages greatly threaten global food security and limit crop production. Hence, increasing crop water stress tolerance is a critical way to secure agricultural production. 24-Epibrassinolide (EBL) and spermine (Spm) are closely involved in plant growth and development, as well as stress tolerance. In this study, the potential role of 0.1 mg L−1 EBL and/or 25 mg L−1 Spm foliage applications in improving the tolerance of maize to water-deficit conditions (50% and 75% field capacity) was investigated. We found that EBL, either alone or in combination with Spm, plays a major role in maize drought tolerance through upregulating the expression of both regulatory genes (ZmBZR1 and ZmBES1) of the brassinosteroid signal transduction pathway and gene-encoding antioxidant defense enzymes ZmSOD, ZmCAT, ZmAPX, ZmMDHAR, ZmDHAR, and ZmGR. Moreover, exogenous treatments alleviated the inhibition of maize plant growth and productivity and mitigated drought-induced oxidative stress by improving antioxidant enzyme (superoxide dismutase, catalase, ascorbate peroxidase, dehydroascorbate reductase, monodehydroascorbate reductase, glutathione reductase) activity, enhancing antioxidant molecule (ascorbate, glutathione) content, preventing reactive oxygen species accumulation, and maintaining cell membrane integrity. These findings reveal that the application of EBL, either individually or in combination with Spm, can be a good strategy for ameliorating water stress in sustainable agricultural systems.

Rootstock effects on bitter pit incidence in 'Honeycrisp' apples are associated with changes in fruit's cell wall chemical properties.

Bitter pit (BP) is a physiological disorder of apples that often appears during or after cold storage. Despite being defined as a calcium deficiency disorder, BP is a complex process that is not only affected by the total Ca2+ content in the fruit but also by the proper cellular Ca2+ homeostasis and partitioning. Early investigations have also suggested that rootstocks could affect BP development and severity. In the present study, rootstock effects on BP development were assessed on ‘Honeycrisp’ trees that were grafted on 14 different rootstocks (B.10, G.11, G.202, G.214, G.30, G.41, G.935, G.969, M.26 EMLA, M.9, V.1, V.5, V.6, and V.7). We evaluated BP incidence at harvest, and three months after cold storage for four, and three growing seasons, respectively. BP incidence was significantly reduced in ‘Honeycrisp’ trees on B.10 compared to other rootstocks, whereas trees on V.6 showed the highest percentage of BP at harvest and after cold storage. ‘Honeycrisp’ apples were collected from three different rootstocks (B.10, G.41, and V.6) two months after cold storage and evaluated for mineral nutrient composition, Ca2+ homeostasis, and cell wall properties, e.g., pectin content, pectin de-esterification rate and pectin methylesterase (PME) activity. Water-soluble and insoluble pectin content was markedly higher in fruits from B.10 than in G.41 and V.6. We also observed increased PME enzyme activity and a greater degree of water-insoluble pectin de-esterification in ‘Honeycrisp’ apples from V.6 compared to those from B.10. A significantly higher Ca2+ was found in the fruits from B.10 than G.41 and V.6. Higher Ca2+ and lower Mg2+ levels were also observed in the cell wall and water-insoluble pectin fractions of the fruits from B.10 compared to G.41 and V.6. However, the ratio of cell wall-bound Ca2+ to total Ca2+ was lower in B.10 compared to G.41 and V.6. Together, our results indicate that the tolerance of B.10 to BP could be attributed to a reduced PME activity and lower pectin de-esterification level, which in turn reduced the amount of Ca2+ cross-linked with pectin, and probably increased the apoplastic free calcium concentrations that is essential for maintaining cell membrane integrity and reducing BP development.

The eisosomes contribute to acid tolerance of yeast by maintaining cell membrane integrity

Microbes have evolved multiple mechanisms to resist environmental stresses, which are regulated in complex and delicate ways. Though the role of cell membranes in acid resistance from the perspective of physicochemical properties and membrane proteins has been deeply studied, the function of eisosomes is still in its infancy. In this study, we firstly reported the dynamic changes of eisosomes under acid stress and the decreased acid tolerance of yeasts caused by eisosome disruption. Physiological indicators and non-targeted lipid profiling revealed that eisosome disruption caused changes in multiple lipids and imbalances in lipid homeostasis, which are responsible for membrane integrity damage. Thus the increased infiltration of carboxylic acids and the raised ROS levels were detected in strains with disrupted eisosome assembly, resulting in decreased cellular tolerance. The results here provide novel insights into the acid-resistant mechanism of yeasts from the perspective of the cell membrane subdomain, which has practical impacts on green biological manufacturing and food preservation.

Origin and evolution of fatty acid desaturase genes in oil crop Brassica napus

Fatty acid (FA) desaturases, as the key enzymes in lipid metabolism, are responsible for biosynthesis of the unsaturated fatty FAs, which play important roles in maintaining cell membrane integrity and multiple stress responses. Although attention has been drawn to some plant FA desaturase genes, their global landscape in oil crops is still lacking. Here, we performed systematic characterization and phylogenomic synteny network analyses of the FA desaturase gene family in polyploid oil crop B. napus and other 54 species covering major streptophyte lineages. A total of 1653 FA desaturase genes were identified from these plant genomes. Based on the broad-scale family phylogeny and functional domains, we proposed a unified eight-group classification system for angiosperm FA desaturases, and found that the origin of genes responsible for FA desaturation evolved early and some genes were absent in different species. Phylogenomic analyses revealed deeply conserved syntenic relationships within each of the eight FA desaturase groups. B. napus contains up to 93 FA desaturase genes from the eight groups. Recurrent duplication events in Brassicaceae contributed to the expansion of FA desaturase genes in B. napus, leading to further functional diversification. These FA desaturase genes exhibited spatio-temporal specific expression patterns in different tissues of B. napus, and a set of FA desaturase genes seem to be orchestrated by key transcriptional factors during seed development, such as zf-HD, B3, GATA3, PEI1, NFYA7, YAB1 and YAB2. Altogether, our data have inferred the evolutionary trajectory of this important gene family across distinct plant lineages, providing theoretical basis for future manipulation of FA desaturase genes to improve the seed oil quality of B. napus.

Biochemical, transcriptomic and metabolomic responses to total dissolved gas supersaturation and their underlying molecular mechanisms in Yangtze sturgeon (Acipenser dabryanus)

With the rapid development of hydropower facility construction, the total dissolved gas (TDG) generated by dam discharge is seriously threatening the survival of fish and has become an ecological environmental issue of global concern. However, how TDG affects fish physiology and the underlying molecular mechanism remain poorly known. In this study, Acipenser dabryanus, an ancient living fossil that is a flagship species of the Yangtze River, was exposed to water supersaturated with TDG at a level of 116% for 48 h. A comprehensive analysis was performed to study the effect of TDG supersaturation stress on A. dabryanus, including histopathological, biochemical, transcriptomic and metabolomic analyses. The histopathological results showed that mucosal-associated lymphoid tissues were seriously damaged after TDG supersaturation stress. Plasma catalase levels increased significantly under TDG supersaturation stress, while superoxide dismutase levels decreased significantly. Transcriptomic analysis revealed 289 upregulated genes and 162 downregulated genes in gill tissue and 535 upregulated and 104 downregulated genes in liver tissue. Metabolomic analysis revealed 63 and 164 differentially abundant metabolites between the control group and TDG group in gill and liver, respectively. The majority of heat shock proteins and genes related to ubiquitin and various immune-related pathways were significantly upregulated by TDG supersaturation stress. Integrated transcriptomic and metabolomic analyses revealed the upregulation of amino acid metabolism and glycometabolism pathways under TDG supersaturation stress. Glycerophospholipid metabolism was increased which might be associated with maintaining cell membrane integrity. This is the first study revealing the underlying molecular mechanisms of effects of TDG supersaturation on fish. Our results suggested that acute TDG supersaturation stress could enhance immune and antioxidative functions and activate energy metabolic pathways as an adaptive mechanism in A. dabryanus.