RESUMO
As a typical C4 plant and important crop worldwide, maize is susceptible to drought. In maize, transitory starch (TS) turnover occurs in the vascular bundle sheath of leaves, differing from that in Arabidopsis (a C3 plant). This process, particularly its role in drought tolerance and the key starch-hydrolyzing enzymes involved, is not fully understood. We discovered that the expression of the ß-amylase (BAM) gene ZmBAM8 is highly upregulated in the drought-tolerant inbred line Chang7-2t. Inspired by this finding, we systematically investigated TS degradation in maize lines, including Chang7-2t, Chang7-2, B104, and ZmBAM8 overexpression (OE) and knockout (KO) lines. We found that ZmBAM8 was significantly induced in the vascular bundle sheath by drought, osmotic stress, and abscisic acid. The stress-induced gene expression and chloroplast localization of ZmBAM8 align with the tissue and subcellular sites where TS turnover occurs. The recombinant ZmBAM8 was capable of effectively hydrolyzing leaf starch. Under drought conditions, the leaf starch in ZmBAM8-OE plants substantially decreased under light, while that in ZmBAM8-KO plants did not decrease. Compared with ZmBAM8-KO plants, ZmBAM8-OE plants exhibited increased drought tolerance. Our study provides insights into the significance of leaf starch degradation in C4 crops and contributes to the development of drought-resistant maize.
Assuntos
Secas , Regulação da Expressão Gênica de Plantas , Folhas de Planta , Amido , Zea mays , beta-Amilase , Zea mays/genética , Zea mays/metabolismo , Zea mays/enzimologia , Amido/metabolismo , beta-Amilase/metabolismo , beta-Amilase/genética , Folhas de Planta/metabolismo , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Plantas Geneticamente Modificadas , Ácido Abscísico/metabolismo , Estresse Fisiológico , Pressão Osmótica , Cloroplastos/metabolismo , Resistência à SecaRESUMO
As a consequence of hypoosmotic shock, yeast cells swell rapidly and increase the surface area by â¼20% in 20 s. Approximately, 35% of this surface increase is mediated by the ER-plasma membrane contact sites, specifically the tricalbins, which are required for the delivery of both lipids and the GPI-anchored protein Crh2 from the cortical ER to the plasma membrane. Therefore, we propose a new function for the tricalbins: mediating the fusion of the ER to the plasma membrane at contact sites. This proposed fusion is triggered by calcium influx via the stretch-gated channel Cch1 and is supported by the anoctamin Ist2.
Assuntos
Membrana Celular , Retículo Endoplasmático , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae , Retículo Endoplasmático/metabolismo , Membrana Celular/metabolismo , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Canais de Cálcio/metabolismo , Lipídeos de Membrana/metabolismo , Fusão de Membrana , Cálcio/metabolismo , Proteínas de Membrana/metabolismo , Pressão OsmóticaRESUMO
Background: Aspergillus cristatus was a filamentous fungus that produced sexual spores under hypotonic stress and asexual spores under hypertonic stress. It could be useful for understanding filamentous fungi's sporulation mechanism. Previously, we conducted functional studies on Achog1, which regulated the hyperosmotic glycerol signaling (HOG) pathway and found that SI65_02513 was significantly downregulated in the transcriptomics data of ΔAchog1 knockout strain. This gene was located at multiple locations in the HOG pathway, indicating that it might play an important role in the HOG pathway of A. cristatus. Furthermore, the function of this gene had not been identified in Aspergillus fungi, necessitating further investigation. This gene's conserved domain study revealed that it has the same protein tyrosine phosphatases (PTPs) functional domain as Saccharomyces cerevisiae, hence SI65_02513 was named Acptp2,3. Methods: The function of this gene was mostly validated using gene knockout and gene complementation approaches. Knockout strains exhibited sexual and asexual development, as well as pigments synthesis. Morphological observations of the knockout strain were carried out under several stress conditions (osmotic stress, oxidative stress, Congo Red, and sodium dodecyl sulfate (SDS). Real-time fluorescence polymerase chain reaction (PCR) identified the expression of genes involved in sporulation, stress response, and pigments synthesis. Results: The deletion of Acptp2,3 reduced sexual and asexual spore production by 4.4 and 4.6 times, demonstrating that Acptp2,3 positively regulated the sporulation of A. cristatus. The sensitivity tests to osmotic stress revealed that ΔAcptp2,3 strains did not respond to sorbitol-induced osmotic stress. However, ΔAcptp2.3 strains grew considerably slower than the wild type in high concentration sucrose medium. The ΔAcptp2,3 strains grew slower than the wild type on media containing hydrogen peroxide, Congo red, and SDS. These findings showed that Acptp2,3 favorably controlled osmotic stress, oxidative stress, and cell wall-damaging chemical stress in A. cristatus. Deleting Acptp2,3 resulted in a deeper colony color, demonstrating that Apctp2,3 regulated pigment synthesis in A. cistatus. The expression levels of numerous stress-and pigments-related genes matched the phenotypic data. Conclusion: According to our findings, Acptp2,3 played an important role in the regulation of sporulation, stress response, and pigments synthesis in A. cristatus. This was the first study on the function of PTPs in Aspergillus fungi.
Assuntos
Aspergillus , Proteínas Fúngicas , Pressão Osmótica , Esporos Fúngicos , Esporos Fúngicos/genética , Esporos Fúngicos/metabolismo , Aspergillus/metabolismo , Aspergillus/genética , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Pigmentos Biológicos/metabolismo , Pigmentos Biológicos/biossíntese , Estresse Fisiológico , Regulação Fúngica da Expressão Gênica , Proteínas Tirosina Fosfatases/metabolismo , Proteínas Tirosina Fosfatases/genética , Técnicas de Inativação de Genes , Estresse Oxidativo , Vermelho Congo/farmacologiaRESUMO
Purpose: This study aims to develop a mathematical model to elucidate fluid circulation in the retina, focusing on the movement of interstitial fluid (comprising water and albumin) to understand the mechanisms underlying exudative macular edema (EME). Methods: The model integrates physiological factors such as retinal pigment epithelium (RPE) pumping, osmotic pressure gradients, and tissue deformation. It accounts for spatial variability in hydraulic conductivity (HC) across the retina and incorporates the structural role of Müller cells (MCs) in maintaining retinal stability. Results: The model predicts that tissue deformation is maximal at the center of the fovea despite fluid exudation from blood capillaries occurring elsewhere, aligning with clinical observations. Additionally, the model suggests that spatial variability in HC across the thickness of the retina plays a protective role against fluid accumulation in the fovea. Conclusions: Despite inherent simplifications and uncertainties in parameter values, this study represents a step toward understanding the pathophysiology of EME. The findings provide insights into the mechanisms underlying fluid dynamics in the retina and fluid accumulation in the foveal region, showing that the specific conformation of Müller cells is likely to play a key role.
Assuntos
Líquido Extracelular , Edema Macular , Epitélio Pigmentado da Retina , Humanos , Edema Macular/fisiopatologia , Edema Macular/metabolismo , Líquido Extracelular/metabolismo , Líquido Extracelular/fisiologia , Epitélio Pigmentado da Retina/patologia , Epitélio Pigmentado da Retina/metabolismo , Epitélio Pigmentado da Retina/fisiopatologia , Células Ependimogliais/metabolismo , Células Ependimogliais/patologia , Modelos Teóricos , Retina/fisiopatologia , Retina/metabolismo , Tomografia de Coerência Óptica , Fóvea Central/patologia , Pressão OsmóticaRESUMO
Plants may encounter abiotic stresses, such as drought, flooding, salinity, and extreme temperatures, thereby negatively affecting their growth, development, and reproduction. In order to enhance their tolerance to such stresses, plants have developed intricate signaling networks that regulate stress-responsive gene expression. For example, Arabidopsis Enhanced Drought Tolerance1/HOMEODOMAIN GLABROUS 11 (AtEDT1/HDG11), one of the transcription factor genes from the group IV of homeodomain-leucine zipper (HD-ZIP) gene family, has been shown to increase drought tolerance in various transgenic plants. However, the underlying molecular mechanisms of enhanced stress tolerance remain unclear. In this study, we identified a homologous gene related to AtEDT1/HDG11, named FaTEDT1L, from the transcriptome sequencing database of cultivated strawberry. Phylogenetic analysis revealed the close relationship of FaTEDT1L with AtEDT1/HDG11, which is one of the group IV members of the HD-ZIP gene family. Yeast one-hybrid analysis showed that FaTEDT1L functions as a transcriptional activator. Transgenic Arabidopsis plants overexpressing FaTEDT1L under the control of the cauliflower mosaic virus (CaMV) 35S promoter exhibited significantly enhanced tolerance to osmotic stress (both drought and salinity) when compared to the wild-type (WT) plants. Under osmotic stress, the average root length was 3.63 ± 0.83 cm, 4.20 ± 1.03 cm, and 4.60 ± 1.14 cm for WT, 35S::FaTEDT1L T2 #3, and 35S:: FaTEDT1L T2 #5, respectively. Substantially increased root length in 35S::FaTEDT1L T2 #3 and 35S::FaTEDT1L T2 #5 was noted when compared to the WT. In addition, the average water loss rates were 64%, 57.1%, and 55.6% for WT, 35S::FaTEDT1L T2 #3, and 35S::FaTEDT1L T2 #5, respectively, after drought treatment, indicating a significant decrease in water loss rate of 35S:: FaTEDT1L T2 #3 and 35S::FaTEDT1L T2 #5 is a critical factor in enhancing plant drought resistance. These findings thus highlight the crucial role of FaTEDT1L in mitigating drought and salt stresses and regulating plant osmotic stress tolerance. Altogether, FaTEDT1L shows its potential usage as a candidate gene for strawberry breeding in improving crop resilience and increasing agricultural productivity under adverse environmental conditions.
Assuntos
Arabidopsis , Fragaria , Regulação da Expressão Gênica de Plantas , Proteínas de Plantas , Plantas Geneticamente Modificadas , Estresse Fisiológico , Arabidopsis/genética , Plantas Geneticamente Modificadas/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Estresse Fisiológico/genética , Fragaria/genética , Fragaria/metabolismo , Fragaria/crescimento & desenvolvimento , Secas , Filogenia , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Pressão Osmótica , Ativação TranscricionalRESUMO
NAC (NAM, ATAF1/2, and CUC2) transcription factors are unique and essential for plant growth and development. Although the NAC gene family has been identified in a wide variety of plants, its chromosomal location and function in Cannabis sativa are still unknown. In this study, a total of 69 putative CsNACs were obtained, and chromosomal location analysis indicated that the CsNAC genes mapped unevenly to 10 chromosomes. Phylogenetic analyses showed that the 69 CsNACs could be divided into six subfamilies. Additionally, the CsNAC genes in group IV-a are specific to Cannabis sativa and contain a relatively large number of exons. Promoter analysis revealed that most CsNAC promoters contained cis-elements related to plant hormones, the light response, and abiotic stress. Furthermore, transcriptome expression profiling revealed that 24 CsNAC genes in two Cannabis sativa cultivars (YM1 and YM7) were significantly differentially expressed under osmotic stress, and these 12 genes presented differential expression patterns across different cultivars according to quantitative real-time PCR (RT-qPCR) analysis. Among these, the genes homologous to the CsNAC18, CsNAC24, and CsNAC61 genes have been proven to be involved in the response to abiotic stress and might be candidate genes for further exploration to determine their functions. The present study provides a comprehensive insight into the sequence characteristics, structural properties, evolutionary relationships, and expression patterns of NAC family genes under osmotic stress in Cannabis sativa and provides a basis for further functional characterization of CsNAC genes under osmotic stress to improve agricultural traits in Cannabis sativa.
Assuntos
Cannabis , Regulação da Expressão Gênica de Plantas , Família Multigênica , Pressão Osmótica , Filogenia , Proteínas de Plantas , Fatores de Transcrição , Cannabis/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Perfilação da Expressão Gênica , Genoma de Planta , Regiões Promotoras Genéticas , Estresse Fisiológico/genética , Cromossomos de Plantas/genética , Mapeamento CromossômicoRESUMO
The surface pre-reacted glass ionomer (S-PRG) filler is a type of bioactive functional glass that releases six different ions. This study examined the effects of the S-PRG filler eluate on Streptococcus mutans in the presence of sucrose. In a solution containing S. mutans, the concentrations of BO33-, Al3+, Sr2+, and F- were significantly higher in the presence of the S-PRG filler eluate than in its absence (p < 0.001). The concentrations of these ions further increased in the presence of sucrose. Additionally, the S-PRG filler eluate significantly reduced glucan formation by S. mutans (p < 0.001) and significantly increased the pH of the bacterial suspension (p < 0.001). Bioinformatic analyses revealed that the S-PRG filler eluate downregulated genes involved in purine biosynthesis (purC, purF, purL, purM, and purN) and upregulated genes involved in osmotic pressure (opuAa and opuAb). At a low pH (5.0), the S-PRG filler eluate completely inhibited the growth of S. mutans in the presence of sucrose and significantly increased the osmotic pressure of the bacterial suspension compared with the control (p < 0.001). These findings suggest that ions released from the S-PRG filler induce gene expression changes and exert an inhibitory effect on S. mutans in the presence of sucrose.
Assuntos
Streptococcus mutans , Sacarose , Streptococcus mutans/efeitos dos fármacos , Streptococcus mutans/crescimento & desenvolvimento , Sacarose/farmacologia , Sacarose/química , Concentração de Íons de Hidrogênio , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Glucanos/farmacologia , Glucanos/química , Propriedades de Superfície , Pressão Osmótica/efeitos dos fármacos , Resinas Acrílicas , Dióxido de SilícioRESUMO
Siberian wildrye (Elymus sibiricus) is a xero-mesophytic forage grass with high nutritional quality and stress tolerance. Among its numerous germplasm resources, some possess superior drought resistance. In this study, we firstly investigated the physiological differences between the leaves of drought-tolerant (DT) and drought-sensitive (DS) genotypes under different field water contents (FWC) in soil culture. The results showed that, under drought stress, DT maintained a lower leaf water potential for water absorption, sustained higher photosynthetic efficiency, and reduced oxidative damage in leaves by efficiently maintaining the ascorbic acid-glutathione (ASA-GSH) cycle to scavenge reactive oxygen species (ROS) compared to DS. Secondly, using RNA sequencing (RNA-seq), we analyzed the gene expression profiles of DT and DS leaves under osmotic stress of hydroponics induced by PEG-6000. Through differential analysis, we identified 1226 candidate unigenes, from which we subsequently screened out 115/212 differentially expressed genes (DEGs) that were more quickly induced/reduced in DT than in DS under osmotic stress. Among them, Unigene0005863 (EsSnRK2), Unigene0053902 (EsLRK10) and Unigene0031985 (EsCIPK5) may be involved in stomatal closure induced by abscisic acid (ABA) signaling pathway. Unigene0047636 (EsCER1) may positively regulates the synthesis of very-long-chain (VLC) alkanes in cuticular wax biosynthesis, influencing plant responses to abiotic stresses. Finally, the contents of wax and cutin were measured by GC-MS under osmotic stress of hydroponics induced by PEG-6000. Corresponding to RNA-seq, contents of wax monomers, especially alkanes and alcohols, showed significant induction by osmotic stress in DT but not in DS. It is suggested that limiting stomatal and cuticle transpiration under drought stress to maintain higher photosynthetic efficiency and water use efficiency (WUE) is one of the critical mechanisms that confer stronger drought resistance to DT. This study provides some insights into the molecular mechanisms underlying drought tolerance in E. sibiricus. The identified genes may provide a foundation for the selection and breeding of drought-tolerant crops.
Assuntos
Secas , Elymus , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Genótipo , Folhas de Planta , Estresse Fisiológico , Folhas de Planta/genética , Folhas de Planta/metabolismo , Estresse Fisiológico/genética , Elymus/genética , Elymus/fisiologia , Elymus/metabolismo , Transcriptoma , Fotossíntese/genética , Pressão OsmóticaRESUMO
Thaumatin-like proteins (TLPs) are conserved proteins involved in the defense and stress responses of plants. Previous studies showed that several TLPs were accumulated in leaf apoplast in Ammopiptanthus mongolicus in winter, indicating that TLPs might be related to the adaptation to winter climate in A. mongolicus. To investigate the roles of TLPs in winter adaptation, we first analyzed the expression pattern of TLP genes in A. mongolicus and then focused on the biological function and regulation pathway of AmTLP25 gene. Several TLP genes, including AmTLP25, were upregulated during winter and in response to both cold and osmotic stress. Overexpression of the AmTLP25 gene led to an increased tolerance of transgenic Arabidopsis to freezing and osmotic stress. Furthermore, the elevated AmWRKY14 transcription factor during winter activated AmTLP25 gene expression by specifically binding to its promoter. It is speculated that the AmWRKY14 - AmTLP25 module contributes to the adaptation to temperate winter climate in A. mongolicus. Our research advances the current understanding of the biological function and regulatory pathway of TLP genes and provides valuable information for understanding the molecular mechanism of temperate evergreen broad-leaved plants adapting to winter climate.
Assuntos
Adaptação Fisiológica , Regulação da Expressão Gênica de Plantas , Proteínas de Plantas , Estações do Ano , Fatores de Transcrição , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Fatores de Transcrição/metabolismo , Fatores de Transcrição/genética , Adaptação Fisiológica/genética , Plantas Geneticamente Modificadas , Arabidopsis/genética , Arabidopsis/metabolismo , Pressão Osmótica , Temperatura BaixaRESUMO
KEY MESSAGE: Natural transformation with R. rhizogenes enhances osmotic stress tolerance in oilseed rape through increasing osmoregulation capacity, enhancing maintenance of hydraulic integrity and total antioxidant capacity. Transformation of plants using wild strains of agrobacteria is termed natural transformation and is not covered by GMO legislation in, e.g., European Union and Japan. In this study, offspring lines of Rhizobium rhizogenes naturally transformed oilseed rape (Brassica napus), i.e., A11 and B3 (termed root-inducing (Ri) lines), were investigated for osmotic stress resilience. Under polyethylene glycol 6000 (PEG) 10% (w/v)-induced osmotic stress, the Ri lines, particularly A11, had less severe leaf wilting, higher stomatal conductance (8.2 times more than WT), and a stable leaf transpiration rate (about 2.9 mmol m-2 s-1). Although the leaf relative water content and leaf water potential responded similarly to PEG treatment between the Ri lines and WT, a significant reduction of the turgid weight to dry weight ratio in A11 and B3 indicated a greater capacity of osmoregulation in the Ri lines. Moreover, the upregulation of plasma membrane intrinsic proteins genes (PIPs) in roots and downregulation of these genes in leaves of the Ri lines implied a better maintenance of hydraulic integrity in relation to the WT. Furthermore, the Ri lines had greater total antioxidant capacity (TAC) than the WT under PEG stress. Collectively, the enhanced tolerance of the Ri lines to PEG-induced osmotic stress could be attributed to the greater osmoregulation capacity, better maintenance of hydraulic integrity, and greater TAC than the WT. In addition, Ri-genes (particularly rolA and rolD) play roles in response to osmotic stress in Ri oilseed rape. This study reveals the potential of R. rhizogenes transformation for application in plant drought resilience.
Assuntos
Brassica napus , Pressão Osmótica , Folhas de Planta , Raízes de Plantas , Brassica napus/genética , Brassica napus/fisiologia , Brassica napus/microbiologia , Raízes de Plantas/microbiologia , Raízes de Plantas/genética , Raízes de Plantas/fisiologia , Folhas de Planta/genética , Folhas de Planta/fisiologia , Agrobacterium/genética , Agrobacterium/fisiologia , Plantas Geneticamente Modificadas , Regulação da Expressão Gênica de Plantas , Polietilenoglicóis/farmacologia , Antioxidantes/metabolismo , Osmorregulação/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Transformação Genética , Água/metabolismoRESUMO
Most albumin in blood plasma is thought to be monomeric with some 5% covalently dimerized. However, many reports in the recent biophysics literature find that albumin is reversibly dimerized or even oligomerized. We review data on this from X-ray crystallography and diverse biophysical techniques. The number-average molecular weight of albumin would be increased by dimerization, affecting size-dependent filtration processes of albumin such as at the glycocalyx of the capillary endothelium and the podocyte slit-diaphragm of the renal glomerulus. If correct, and depending on characteristics of the process, such as Kd, reversible dimerization of albumin in plasma would have major implications for normal physiology and medicine. We present quantitative models of the impact of dimerization on albumin molecular forms, on the number-average molecular weight of albumin, and estimate the effect on the colloid osmotic pressure of albumin. Dimerization reduces colloid osmotic pressure as total albumin concentration increases below that expected in the absence of dimerization. Current models of albumin filtration by the renal glomerulus would need revision to account for the dynamic size of albumin molecules filtered. More robust biophysical data are needed to give a definitive answer to the questions posed and we suggest possible approaches to this.
Assuntos
Multimerização Proteica , Humanos , Animais , Albumina Sérica/metabolismo , Dimerização , Pressão Osmótica , Glomérulos Renais/metabolismo , Peso MolecularRESUMO
Turgor is the driving force of plant growth, making it possible for roots to overcome soil resistance or for stems to counteract gravity. Maintaining a constant growth rate while avoiding cell content dilution, which would progressively stop the inward water flux, imposes the production or import of osmolytes in proportion to the increase of volume. We coin this phenomenon stationary osmoregulation. The article explores the quantitative consequences of this hypothesis on the interaction of a cylindrical cell growing axially against an obstacle. An instantaneous axial compression of a pressurized cylindrical cell generates a force and a pressure jump, which both decrease towards a lower value once water has flowed out of the cell to reach the water potential equilibrium. In the first part, the article derives analytical formulae for these forces and over-pressure both before and after relaxation. In the second part, we describe how the coupling of the Lockhart growth law with the stationary osmoregulation hypothesis predicts a transient slowdown in growth due to contact before a re-acceleration in growth. We finally compare these predictions with the output of an elastic growth model which ignores the osmotic origin of growth: models only match in the early phase of contact for a high-stiffness obstacle.
Assuntos
Modelos Biológicos , Osmorregulação/fisiologia , Água/metabolismo , Pressão OsmóticaRESUMO
Diurnal floret opening time (DFOT) is a pivotal trait for successful fertilization and hybrid breeding in rice. However, the molecular mechanism underlying this trait is poorly understood in rice. In this study, we combined the cytological, genetic and molecular studies to demonstrate that jasmonic acid (JA) regulates DFOT in rice through modulating the turgor and osmotic pressure of the lodicules. We show that lodicules undergo dramatic morphologic changes, accompanied by changes in water and sugar contents during the process of floret opening. Consistently, a large set of genes associated with cell osmolality and cell wall remodeling exhibits distinct expression profiles at different time points in our time-course transcriptomes of lodicules. Notably, a group of JA biosynthesis and signaling genes is continuously upregulated, accompanied by a gradual increase in JA accumulation as floret opening approaching. Furthermore, we demonstrate that the JA biosynthesis gene OsAOS1 is required for endogenous JA biosynthesis in lodicules and promoting rice DFOT. Moreover, OsMYC2, a master regulator of JA signaling, regulates rice DFOT by directly activating OsAOS1, OsSWEET4, OsPIP2;2 and OsXTH9. Collectively, our findings establish a core regulatory network mediated by JA for modulating rice DFOT and provide effective gene targets for the genetic improvement of DFOT in rice.
Assuntos
Ritmo Circadiano , Ciclopentanos , Regulação da Expressão Gênica de Plantas , Redes Reguladoras de Genes , Oryza , Oxilipinas , Proteínas de Plantas , Oryza/genética , Oryza/fisiologia , Oryza/metabolismo , Ciclopentanos/metabolismo , Oxilipinas/metabolismo , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Ritmo Circadiano/genética , Ritmo Circadiano/fisiologia , Flores/fisiologia , Flores/genética , Transdução de Sinais , Genes de Plantas , Pressão Osmótica , Fatores de Tempo , Água/metabolismo , Transcriptoma/genéticaRESUMO
Cell size is a crucial physical property that significantly impacts cellular physiology and function. However, the influence of cell size on stem cell specification remains largely unknown. Here, we investigated the dynamic changes in cell size during the differentiation of human pluripotent stem cells into definitive endoderm (DE). Interestingly, cell size exhibited a gradual decrease as DE differentiation progressed with higher stiffness. Furthermore, the application of hypertonic pressure or chemical to accelerate the reduction in cell size significantly and specifically enhanced DE differentiation. By functionally intervening in mechanosensitive elements, we have identified actomyosin activity as a crucial mediator of both DE differentiation and cell size reduction. Mechanistically, the reduction in cell size induces actomyosin-dependent angiomotin (AMOT) nuclear translocation, which suppresses Yes-associated protein (YAP) activity and thus facilitates DE differentiation. Together, our study has established a novel connection between cell size diminution and DE differentiation, which is mediated by AMOT nuclear translocation. Additionally, our findings suggest that the application of osmotic pressure can effectively promote human endodermal lineage differentiation.
Assuntos
Actomiosina , Angiomotinas , Diferenciação Celular , Tamanho Celular , Endoderma , Transdução de Sinais , Fatores de Transcrição , Proteínas de Sinalização YAP , Humanos , Endoderma/citologia , Endoderma/metabolismo , Actomiosina/metabolismo , Proteínas de Sinalização YAP/metabolismo , Fatores de Transcrição/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/genética , Pressão Osmótica , Células-Tronco Pluripotentes/metabolismo , Células-Tronco Pluripotentes/citologia , Núcleo Celular/metabolismoRESUMO
Water scarcity is a major environmental constraint on plant growth in arid regions. Soluble sugars and amino acids are essential osmolytes for plants to cope with osmotic stresses. Sweet sorghum is an important bioenergy crop and forage with strong adaptabilities to adverse environments; however, the accumulation pattern and biosynthesis basis of soluble sugars and amino acids in this species under osmotic stresses remain elusive. Here, we investigated the physiological responses of a sweet sorghum cultivar to PEG-induced osmotic stresses, analyzed differentially accumulated soluble sugars and amino acids after 20% PEG treatment using metabolome profiling, and identified key genes involved in the biosynthesis pathways of soluble sugars and amino acids using transcriptome sequencing. The results showed that the growth and photosynthesis of sweet sorghum seedlings were significantly inhibited by more than 20% PEG. After PEG treatments, the leaf osmotic adjustment ability was strengthened, while the contents of major inorganic osmolytes, including K+ and NO3-, remained stable. After 20% PEG treatment, a total of 119 and 188 differentially accumulated metabolites were identified in the stems and leaves, respectively, and the accumulations of soluble sugars such as raffinose, trehalose, glucose, sucrose, and melibiose, as well as amino acids such as proline, leucine, valine, serine, and arginine were significantly increased, suggesting that these metabolites should play key roles in osmotic adjustment of sweet sorghum. The transcriptome sequencing identified 1711 and 4978 DEGs in the stems, as well as 2061 and 6596 DEGs in the leaves after 20% PEG treatment for 6 and 48 h, respectively, among which the expressions of genes involved in biosynthesis pathways of sucrose (such as SUS1, SUS2, etc.), trehalose (including TPS6), raffinose (such as RAFS2 and GOLS2, etc.), proline (such as P5CS2 and P5CR), leucine and valine (including BCAT2), and arginine (such as ASS and ASL) were significantly upregulated. These genes should be responsible for the large accumulation of soluble sugars and amino acids under osmotic stresses. This study deepens our understanding of the important roles of individual soluble sugars and amino acids in the adaptation of sweet sorghum to water scarcity.
Assuntos
Aminoácidos , Regulação da Expressão Gênica de Plantas , Metaboloma , Pressão Osmótica , Sorghum , Sorghum/metabolismo , Sorghum/genética , Aminoácidos/metabolismo , Açúcares/metabolismo , Perfilação da Expressão Gênica/métodos , Folhas de Planta/metabolismo , Folhas de Planta/genética , Transcriptoma , Vias Biossintéticas , FotossínteseRESUMO
Cataracts are the world's leading cause of blindness, and diabetes is the second leading risk factor for cataracts after old age. Despite this, no preventative treatment exists for cataracts. The altered metabolism of excess glucose during hyperglycaemia is known to be the underlying cause of diabetic cataractogenesis, resulting in localised disruptions to fibre cell morphology and cell swelling in the outer cortex of the lens. In rat models of diabetic cataracts, this damage has been shown to result from osmotic stress and oxidative stress due to the accumulation of intracellular sorbitol, the depletion of NADPH which is used to regenerate glutathione, and the generation of fructose metabolites via the polyol pathway. However, differences in lens physiology and the metabolism of glucose in the lenses of different species have prevented the translation of successful treatments in animal models into effective treatments in humans. Here, we review the stresses that arise from hyperglycaemic glucose metabolism and link these to the regionally distinct metabolic and physiological adaptations in the lens that are vulnerable to these stressors, highlighting the evidence that chronic oxidative stress together with osmotic stress underlies the aetiology of human diabetic cortical cataracts. With this information, we also highlight fundamental gaps in the knowledge that could help to inform new avenues of research if effective anti-diabetic cataract therapies are to be developed in the future.
Assuntos
Catarata , Complicações do Diabetes , Pressão Osmótica , Estresse Oxidativo , Polímeros , Catarata/metabolismo , Catarata/etiologia , Catarata/patologia , Humanos , Animais , Complicações do Diabetes/metabolismo , Polímeros/metabolismo , Cristalino/metabolismo , Cristalino/patologia , Sorbitol/metabolismo , Hiperglicemia/metabolismo , Hiperglicemia/complicações , Glucose/metabolismoRESUMO
The choline-glycine betaine pathway plays an important role in bacterial survival in hyperosmotic environments. Osmotic activation of the choline transporter BetT promotes the uptake of external choline for synthesizing the osmoprotective glycine betaine. Here, we report the cryo-electron microscopy structures of Pseudomonas syringae BetT in the apo and choline-bound states. Our structure shows that BetT forms a domain-swapped trimer with the C-terminal domain (CTD) of one protomer interacting with the transmembrane domain (TMD) of a neighboring protomer. The substrate choline is bound within a tryptophan prism at the central part of TMD. Together with functional characterization, our results suggest that in Pseudomonas species, including the plant pathogen P. syringae and the human pathogen Pseudomonas aeruginosa, BetT is locked at a low-activity state through CTD-mediated autoinhibition in the absence of osmotic stress, and its hyperosmotic activation involves the release of this autoinhibition.
Assuntos
Proteínas de Bactérias , Colina , Microscopia Crioeletrônica , Proteínas de Membrana Transportadoras , Proteínas de Membrana Transportadoras/metabolismo , Proteínas de Membrana Transportadoras/química , Colina/metabolismo , Colina/química , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/química , Pseudomonas syringae/metabolismo , Modelos Moleculares , Osmorregulação , Pressão Osmótica , Betaína/metabolismo , Conformação Proteica , Ligação Proteica , Relação Estrutura-Atividade , Domínios ProteicosRESUMO
Most studies on anesthesia focus on the nervous system of mammals due to their interest in medicine. The fact that any life form can be anaesthetised is often overlooked although anesthesia targets ion channel activities that exist in all living beings. This study examines the impact of lidocaine on rice (Oryza sativa). It reveals that the cellular responses observed in rice are analogous to those documented in animals, encompassing direct effects, the inhibition of cellular responses, and the long-distance transmission of electrical signals. We show that in rice cells, lidocaine has a cytotoxic effect at a concentration of 1%, since it induces programmed reactive oxygen species (ROS) and caspase-like-dependent cell death, as already demonstrated in animal cells. Additionally, lidocaine causes changes in membrane ion conductance and induces a sharp reduction in electrical long-distance signaling following seedlings leaves burning. Finally, lidocaine was shown to inhibit osmotic stress-induced cell death and the regulation of Ca2+ homeostasis. Thus, lidocaine treatment in rice and tobacco (Nicotiana benthamiana) seedlings induces not only cellular but also systemic effects similar to those induced in mammals.
Assuntos
Lidocaína , Oryza , Espécies Reativas de Oxigênio , Oryza/efeitos dos fármacos , Oryza/metabolismo , Lidocaína/farmacologia , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais/efeitos dos fármacos , Cálcio/metabolismo , Morte Celular/efeitos dos fármacos , Células Cultivadas , Pressão Osmótica/efeitos dos fármacos , Anestésicos/farmacologiaRESUMO
The interior of cellular nuclei, the nucleoplasm, is a crowded fluid that is pervaded by protein-decorated DNA polymers, the chromatin. Due to the complex architecture of chromatin and a multitude of associated nonequilibrium processes, e.g., DNA repair, the nucleoplasm can be expected to feature nontrivial material properties and hence anomalous transport phenomena. Here, we have used single-particle tracking on nuclear actin rods to probe such transport phenomena. Our analysis reveals that short actin rods in the nucleus show an intermittent, antipersistent subdiffusion with clear signatures of fractional Brownian motion. Moreover, the diffusive motion is heterogeneous with clear signatures of an intermittent switching of trajectories between at least two different mobilities, most likely due to transient associations with chromatin. In line with this interpretation, hyperosmotic stress is seen to stall the motion of nuclear actin rods, whereas hypo-osmotic conditions yield a reptationlike motion. Our data highlights the heterogeneity of transport in the nucleoplasm that needs to be taken into account for an understanding of nucleoplasmic organization and the mechanobiology of nuclei.
Assuntos
Actinas , Núcleo Celular , Cromatina , Difusão , Actinas/metabolismo , Cromatina/metabolismo , Núcleo Celular/metabolismo , Animais , Modelos Biológicos , Pressão OsmóticaRESUMO
MicroRNAs play crucial regulatory roles in various aspects of development and physiology, including environmental adaptation and stress responses in teleosts. RT-qPCR is the most commonly used method for studying microRNA expression, with the accuracy and reliability of results depending on the use of an appropriate reference gene for normalization. This study aimed to evaluate seven miRNAs (U6, Let-7a, miR-23a, miR-25-3, miR-103, miR-99-5, and miR-455) expression stability in different tissues of Nile tilapia subjected to osmotic stress. Fish were divided into two groups: a control and an experimental group, raised in 0 and 12 ppt salinity water respectively. After 21 days, brain, gills, liver, and posterior intestine were collected for analysis. Different mathematical algorithms (geNorm, NormFinder, BestKeeper, and the comparative ΔCt method) were employed to identify the most suitable reference miRNAs. The results indicate that the miR-455/miR-23a combination is a robust reference for normalizing miRNA expression levels in studies of osmotic stress responses in Nile tilapia. The stability of miRNA expression can vary depending on specific stress conditions and biological processes, underscoring the necessity of selecting appropriate normalizing miRNAs for each experimental context. This study identifies reliable reference genes for future RT-qPCR analyses of miRNA expression, thereby enhancing our understanding of molecular responses in fish to environmental challenges. These insights are fundamental to the development of new technologies for the improved management and sustainability of aquaculture practices.