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This study thoroughly examines three cetacean monitoring methods and assessing their advantages and limitations, establishing a foundational basis for comprehensive information on composition, distribution, and behavior. While real-time and non-invasive, visual surveys favor surface-active cetaceans and are weather-dependent. Local ecological knowledge supplements insights into group behavior. Environmental DNA (eDNA) analysis efficiently detects species like the narrow-ridged finless porpoise (Neophocaena asiaeorientalis) and common bottlenose dolphin (Tursiops truncatus), offering non-invasive, and spatially adept monitoring. Furthermore, eDNA provides prey species information, revealing the narrow-ridged finless porpoise's winter migration to deeper waters due to prey distribution. The study identifies prevalent prey species, like the Japanese Anchovy (Engraulis japonicus) and Osbeck's grenadier anchovy (Coilia mystus), offering insights into the porpoise's feeding ecology and adaptation to changing prey availability in winter. This study systematically compares diverse methodologies employed in cetacean surveys, thereby yielding a comprehensive understanding of cetacean distribution, behavior, and feeding ecology.
Subject(s)
Cetacea , Conservation of Natural Resources , Environmental Monitoring , Animals , Environmental Monitoring/methods , China , Porpoises , DNA, Environmental , Oceans and Seas , Bottle-Nosed Dolphin/physiologyABSTRACT
With the continuous advancement of urbanization and industrialization, non-grain production on cropland (NGPCL) is gradually becoming more widespread. This phenomenon will compress the space for grain production and trigger a global food crisis. How to scientifically understand and effectively control NGPCL has become a scientific issue. This study, conducted at the plot scale, establishes a measurement index for NGPCL and further explores the characteristics and driving mechanisms of NGPCL in mountainous areas. The results indicate the following: (1) Compared to plots for food-growing, plots for non-grain production tend to be more dispersed, with terraces showing the most significant dispersion, while plains exhibit the highest degree of aggregation. (2) In terms of irrigation conditions, irrigated land and dry land are more likely to undergo NGPCL. In terms of topography, slope croplands have the highest probability of being used for NGPCL. (3) Regions with steeper slopes, higher elevations, greater differences in altitude from the settlement, farther distances from settlements and roads, yet closer proximity to forests, are more likely to engage in NGPCL. (4) Different plot characteristics have varying impacts on NGPCL. Plot characteristics primarily affect the costs and returns of grain production, driving farmers to change their production patterns and triggering NGPCL.
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OBJECTIVE: Accurately predicting knee osteoarthritis (KOA) is essential for early detection and personalized treatment. We aimed to develop and test a magnetic resonance imaging (MRI)-based joint space (JS) radiomic model (RM) to predict radiographic KOA incidence through neural networks by integrating meniscus and femorotibial cartilage radiomic features. METHODS: In the Osteoarthritis Initiative cohort, participants with knees without radiographic KOA at baseline but at high risk for radiographic KOA were included. Patients' knees developed radiographic KOA, whereas control knees did not over four years. We randomly split the participants into development and test cohorts (8:2) and extracted features from baseline three-dimensional double-echo steady-state sequence MRI. Model performance was evaluated using an area under the receiver operating characteristic curve (AUC), sensitivity, and specificity in both cohorts. Nine resident surgeons performed the reader experiment without/with the JS-RM aid. RESULTS: Our study included 549 knees in the development cohort (275 knees of patients with KOA vs 274 knees of controls) and 137 knees in the test cohort (68 knees of patients with KOA vs 69 knees of controls). In the test cohort, JS-RM had a favorable accuracy for predicting the radiographic KOA incidence with an AUC of 0.931 (95% confidence interval [CI] 0.876-0.963), a sensitivity of 84.4% (95% CI 83.9%-84.9%), and a specificity of 85.6% (95% CI 85.2%-86.0%). The mean specificity and sensitivity of resident surgeons through MRI reading in predicting radiographic KOA incidence were increased from 0.474 (95% CI 0.333-0.614) and 0.586 (95% CI 0.429-0.743) without the assistance of JS-RM to 0.874 (95% CI 0.847-0.901) and 0.812 (95% CI 0.742-0.881) with JS-RM assistance, respectively (P < 0.001). CONCLUSION: JS-RM integrating the features of the meniscus and cartilage showed improved predictive values in radiographic KOA incidence.
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The mechanism by which brown adipose tissue (BAT) regulates bone metabolism is unclear. Here, we reveal that BAT secretes S100A8/A9, a previously unidentified BAT adipokine (batokine), to impair bone formation. Brown adipocytes-specific knockout of Rheb (RhebBAD KO), the upstream activator of mTOR, causes BAT malfunction to inhibit osteogenesis. Rheb depletion induces NF-κB dependent S100A8/A9 secretion from brown adipocytes, but not from macrophages. In wild-type mice, age-related Rheb downregulation in BAT is associated with enhanced S100A8/A9 secretion. Either batokines from RhebBAD KO mice, or recombinant S100A8/A9, inhibits osteoblast differentiation of mesenchymal stem cells in vitro by targeting toll-like receptor 4 on their surfaces. Conversely, S100A8/A9 neutralization not only rescues the osteogenesis repressed in the RhebBAD KO mice, but also alleviates age-related osteoporosis in wild-type mice. Collectively, our data revealed an unexpected BAT-bone crosstalk driven by Rheb-S100A8/A9, uncovering S100A8/A9 as a promising target for the treatment, and potentially, prevention of osteoporosis.
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Background: Though anterior cruciate ligament (ACL) tear has been widely accepted as an important accelerator for knee osteoarthritis (KOA), the role of intrinsic ACL degeneration in developing KOA has not been fully investigated. Purpose: To determine whether ACL degeneration, in the absence of ACL tear, is associated with incident KOA over 4 years. Study design: Cohort study; Level of evidence, 2. Methods: Participants' knees in this nested case-control study were selected from the Osteoarthritis Initiative (OAI) study, with Kellgren-Lawrence grading (Kellgren-Lawrence grading) of 0 or 1 âat baseline (BL). Case knees which had incident KOA (KLG ≥2) over 4 years, were matched 1:1 with control knees by gender, age and radiographic status. ACL signal intensity alteration (0-3 scale) and volume were assessed as compositional feature and morphology of ACL degeneration, using knee MRI at P0 (time of onset of incident KOA), P-1 (1 year prior to P0) and baseline. Conditional logistic regression was applied to analyze the association between measures of ACL degeneration and incident KOA. Results: 337 case knees with incident KOA were matched to 337 control knees. Participants were mostly female (68.5%), with an average age of 59.9 years old. ACL signal intensity alterations at BL, P-1 and P0 were significantly associated with an increased odds of incident KOA respectively (all P for trend ≤0.001). In contrast, ACL volumes were not significantly associated with incident KOA at any time points. Conclusions: ACL signal intensity alteration is associated with increased incident KOA over 4 years, whereas ACL volume is not.The translational potential of this article: This paper focused on ACL signal intensity alteration which could better reflect ACL degeneration rather than ACL tear during the progression of KOA and explored this topic in a nested case-control study. Utilizing MR images from KOA participants, we extracted the imaging features of ACL. In addition, we established a semi-quantitative score for ACL signal intensity alteration and found a significant correlation between it and KOA incidence. Our findings confirmed that the more severe the ACL signal intensity alteration, the stronger relationship with the occurrence of KOA. This suggests that more emphasis should be placed on ACL degeneration rather than ACL integrity in the future.
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Monascus pilosus has been used to produce lipid-lowering drugs rich in monacolin K (MK) for a long period. Genome mining reveals there are still many potential genes worth to be explored in this fungus. Thereby, efficient genetic manipulation tools will greatly accelerate this progress. In this study, we firstly developed the protocol to prepare protoplasts for recipient of CRISPR/Cas9 system. Subsequently, the vector and donor DNA were co-transformed into recipients (106 protoplasts/mL) to produce 60-80 transformants for one test. Three genes (mpclr4, mpdot1, and mplig4) related to DNA damage response (DDR) were selected to compare the gene replacement frequencies (GRFs) of Agrobacterium tumefaciens-mediated transformation (ATMT) and CRISPR/Cas9 gene editing system (CGES) in M. pilosus MS-1. The results revealed that GRF of CGES was approximately five times greater than that of ATMT, suggesting that CGES was superior to ATMT as a targeting gene editing tool in M. pilosus MS-1. The inactivation of mpclr4 promoted DDR via the non-homologous end-joining (NHEJ) and increased the tolerances to DNA damaging agents. The inactivation of mpdot1 blocked DDR and led to the reduced tolerances to DNA damaging agents. The inactivation of mplig4 mainly blocked the NHEJ pathway and led to obviously reduced tolerances to DNA damaging agents. The submerged fermentation showed that the ability to produce MK in strain Δmpclr4 was improved by 52.6% compared to the wild type. This study provides an idea for more effective exploration of gene functions in Monascus strains. KEY POINTS: ⢠A protocol of high-quality protoplasts for CGES has been developed in M. pilosus. ⢠The GRF of CGES was about five times that of ATMT in M. pilosus. ⢠The yield of MK for Δmpclr4 was enhanced by 52.6% compared with the wild type.
Subject(s)
Gene Editing , Monascus , Monascus/genetics , Monascus/metabolism , CRISPR-Cas Systems , Gene Targeting/methods , Lovastatin/metabolism , Agrobacterium tumefaciens/genetics , DNA/metabolismABSTRACT
Increasing data suggested that histone methylation modification plays an important role in regulating biosynthesis of secondary metabolites (SMs). Monascus spp. have been applied to produce hypolipidemic drug lovastatin (also called monacolin K, MK) and edible Monascus-type azaphilone pigments (MonAzPs). However, little is known about how histone methylation regulates MK and MonAzPs. In this study, we constructed H3K9 methyltransferase deletion strain ΔMpDot1 and H4K20 methyltransferase deletion strain ΔMpSet9 using Monascus pilosus MS-1 as the parent. The result showed that deletion of MpDot1 reduced the production of MK and MonAzPs, and deletion of MpSet9 increased MonAzPs production. Real-time quantitative PCR (RT-qPCR) showed inactivation of mpdot1 and mpset9 disturbed the expression of genes responsible for the biosynthesis of MK and MonAzPs. Western blot suggested that deletion of MpDot1 reduced H3K79me and H4K16ac, and deletion of MpSet9 decreased H4K20me3 and increased H4pan acetylation. Chromatin immunoprecipitation coupled with quantitative PCR (ChIP-qPCR) showed ΔMpDot1 strain and ΔMpSet9 strain reduced the enrichment of H3K79me2 and H4K20me3 in the promoter regions of key genes for MK and MonAzPs biosynthesis, respectively. These results suggested that MpDot1 and MpSet9 affected the synthesis of SMs by regulating gene transcription and histone crosstalk, providing alternative approach for regulation of lovastatin and MonAzPs.
Subject(s)
Lovastatin , Monascus , Lovastatin/pharmacology , Histones/metabolism , Histone-Lysine N-Methyltransferase/genetics , Histone-Lysine N-Methyltransferase/metabolism , Monascus/genetics , Monascus/metabolismABSTRACT
Accurately modeling the distribution of keystone species is of utmost importance to gain a comprehensive understanding of their complex ecological dynamics and to develop effective strategies for sustainable scientific management. In the coastal China ecosystem, the swordtip squid (Uroteuthis edulis) stands out as a keystone species with significant commercial and ecological value. Despite its importance, research on the ecological dynamics of this species remains limited and requires further investigation. To investigate the spatial and temporal variability in the distribution of U. edulis and identify the key environmental drivers in the East China Sea (ECS) and southern Yellow Sea across different seasons, we generated ensemble models using oceanographic variables and fishery-independent scientific survey data collected from 2016 to 2018. Our results revealed that U. edulis predominantly inhabited the central and southern regions of the ECS throughout the year. The primary environmental variables driving its distribution varied by season, with the sea surface temperature being the most important in spring, sea surface height in summer and autumn, and depth in winter. During summer and autumn, the suitable habitats of U. edulis were found to be largest and extended northwards towards the coastline. However, they migrated southwards to the waters near the edge of the ECS continental shelf with smaller suitable areas in the spring and winter. These results suggested that U. edulis exhibited season-specific habitat preferences and responded to changing environmental conditions throughout the year. The observed seasonal distribution patterns were likely influenced by the fluctuating mixture of waters (ocean currents) from different sources, with varying physical and chemical characteristics throughout the year. Our study provides baseline data for comprehending the population dynamics of U. edulis and highlights the significance of considering species' habitat preferences in a dynamic environment.
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OBJECTIVES: This study aims to identify circulating proteins that are causally associated with osteoarthritis (OA)-related traits through Mendelian randomisation (MR)-based analytical framework. METHODS: Large-scale two-sample MR was employed to estimate the effects of thousands of plasma proteins on 12 OA-related traits. Additional analyses including Bayesian colocalisation, Steiger filtering analysis, assessment of protein-altering variants and mapping expression quantitative trait loci to protein quantitative trait loci were performed to investigate the reliability of the MR findings; protein-protein interaction, pathway enrichment analysis and evaluation of drug targets were conducted to deepen the understanding and identify potential therapeutic targets of OA. RESULTS: Dozens of circulating proteins were identified to have putatively causal effects on OA-related traits, and a majority of these proteins were either drug targets or considered druggable. CONCLUSIONS: Through MR analysis, we have identified numerous plasma proteins associated with OA-related traits, shedding light on protein-mediated mechanisms and offering promising therapeutic targets for OA.
Subject(s)
Osteoarthritis , Proteome , Humans , Bayes Theorem , Reproducibility of Results , Osteoarthritis/genetics , Blood Proteins/geneticsABSTRACT
Osteoarthritis (OA) is a prevalent and severely debilitating disease with an unmet medical need. In order to alleviate OA symptoms or prevent structural progression of OA, new drugs, particularly disease-modifying osteoarthritis drugs (DMOADs), are required. Several drugs have been reported to attenuate cartilage loss or reduce subchondral bone lesions in OA and thus potentially be DMOADs. Most biologics (including interleukin-1 (IL-1) and tumor necrosis factor (TNF) inhibitors), sprifermin, and bisphosphonates failed to yield satisfactory results when treating OA. OA clinical heterogeneity is one of the primary reasons for the failure of these clinical trials, which can require different therapeutic approaches based on different phenotypes. This review describes the latest insights into the development of DMOADs. We summarize in this review the efficacy and safety profiles of various DMOADs targeting cartilage, synovitis, and subchondral bone endotypes in phase 2 and 3 clinical trials. To conclude, we summarize the reasons for clinical trial failures in OA and suggest possible solutions.
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Objective: To assess the causal effect of systemic iron status by using four biomarkers (serum iron; transferrin saturation; ferritin; total iron-binding capacity) on knee osteoarthritis (OA), hip OA, total knee replacement, and total hip replacement using 2-sample Mendelian randomization (MR) design. Methods: Three instrument sets were used to construct the genetic instruments for the iron status: Liberal instruments (variants associated with one of the iron biomarkers), sensitivity instruments (liberal instruments exclude variants associated with potential confounders), and conservative instruments (variants associated with all four iron biomarkers). Summary-level data for four OA phenotypes, including knee OA, hip OA, total knee replacement, and total hip replacement were obtained from the largest genome-wide meta-analysis with 826,690 individuals. Inverse-variance weighted based on the random-effect model as the main approach was conducted. Weighted median, MR-Egger, and Mendelian randomization pleiotropy residual sum and outlier methods were used as sensitivity MR approaches. Results: Based on liberal instruments, genetically predicted serum iron and transferrin saturation were significantly associated with hip OA and total hip replacement, but not with knee OA and total knee replacement. Statistical evidence of heterogeneity across the MR estimates indicated that mutation rs1800562 was the SNP significantly associated with hip OA in serum iron (odds ratio, OR = 1.48), transferrin saturation (OR = 1.57), ferritin (OR = 2.24), and total-iron binding capacity (OR = 0.79), and hip replacement in serum iron (OR = 1.45), transferrin saturation (OR = 1.25), ferritin (OR = 1.37), and total-iron binding capacity (OR = 0.80). Conclusion: Our study suggests that high iron status might be a causal factor of hip OA and total hip replacement where rs1800562 is the main contributor.
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OBJECTIVE: The aim of this study was to explore the association between quadriceps strength and synovitis in knee osteoarthritis (KOA). METHODS: This study was derived from the Osteoarthritis Initiative (OAI), which recruited adults from the OAI cohort with or at risk of KOA. Knees with complete records of isometric quadriceps strength and effusion-synovitis and Hoffa-synovitis assessments were included. Quadriceps strength was measured isometrically at baseline. Effusion-synovitis and Hoffa-synovitis were measured using the Magnetic Resonance Imaging Osteoarthritis Knee Score at baseline and at 1-year and 2-year follow-ups. Generalized estimating equations were used to analyze the associations of baseline quadriceps strength with changes in effusion-synovitis and Hoffa-synovitis in multivariable analyses. Additionally, analyses were stratified by synovitis-driven inflammatory phenotypes. RESULTS: A total of 1513 knees were included in this study. In total, 61% of the subjects were female; subjects had an average age of 61.9 (SD 8.8) years and a mean BMI of 29.4 (SD 4.7). Regarding the whole population, baseline quadriceps strength was negatively associated with baseline effusion-synovitis and follow-up changes in effusion-synovitis (odds ratio [OR] 0.77-0.86), but no significant association was observed in terms of Hoffa-synovitis. Stratified by synovitis-driven inflammatory phenotype, baseline quadriceps strength was significantly associated with follow-up changes in effusion-synovitis-but not in Hoffa-synovitis-in the population with existing effusion-synovitis (OR 0.75-0.79). CONCLUSION: Higher baseline quadriceps strength was negatively associated with changes in effusion-synovitis-but not in Hoffa-synovitis-especially in the population with existing effusion-synovitis. Our findings suggested a potential protective role of the quadriceps in effusion-synovitis.
Subject(s)
Osteoarthritis, Knee , Synovitis , Humans , Female , Male , Osteoarthritis, Knee/complications , Osteoarthritis, Knee/diagnostic imaging , Osteoarthritis, Knee/epidemiology , Knee Joint/diagnostic imaging , Knee Joint/pathology , Synovitis/pathology , Magnetic Resonance Imaging/methods , Quadriceps Muscle/diagnostic imaging , Quadriceps Muscle/pathologyABSTRACT
Following the publication of the above article, an interested reader drew to the authors' attention that Figs. 1C and 2 in the paper appeared to contain instances of duplicated data. The authors were able to consult their original data files, and realized that these figures had indeed been assembled incorrectly. Moreover, they identified further errors with a number of the other figures in their published formats (specifically, Figs. 3, 4, 6 and 7), and requested that a corrigendum be published to take account of all the errors that were made during the compilation of these figures. The Editor of International Journal of Molecular Medicine has considered the authors' request to publish a corrigendum, but has declined this request on account of the large number of errors that have been identified, and subsequently determined that this article should be retracted from the Journal on the basis of an overall lack of confidence in the presented data. Upon receiving this decision from the Editor, the authors were in agreement that the article should be retracted. The Editor apologizes to the readership of the Journal for any inconvenience caused. [International Journal of Molecular Medicine 39: 527538, 2017; DOI: 10.3892/ijmm.2017.2880].
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BACKGROUND: Osteoarthritis (OA), the most common joint disease in the elderly, has no cure. Macroelements are vital in human health and their relationships with OA are not clear. Clarifying the relationships between macroelements and OA may assist knee OA management. METHODS: This study was a post-hoc analysis using data from a two-year randomized controlled trial among 392 participants with knee OA. Dietary macroelements, including calcium, magnesium, potassium, and phosphorus were computed-based on a semi-quantitative food frequency questionnaire at baseline. Knee joint structures (including cartilage volume, cartilage defect, bone marrow lesions, and effusion-synovitis volume), OA symptoms, quality of life, and OA comorbid conditions (including lower limb muscle strength and depressive symptoms) were assessed at baseline and month 24. Western Ontario and McMaster Universities (WOMAC) Index and depressive symptoms were assessed at baseline and months 3, 6, 12, and 24. Quality of life and lower limb muscle strength were assessed at baseline and months 6, 12, and 24. All analyses were conducted using mixed-effects models. RESULTS: Higher dietary magnesium and potassium were associated with fewer OA symptoms, higher quality of life, greater lower limb muscle strength, and fewer depressive symptoms, but not with knee joint structures. Higher dietary calcium and phosphorus was not associated with any of the OA-related outcomes, except that dietary phosphorus was associated with greater lower limb muscle strength. CONCLUSIONS: In the longitudinal analyses, higher dietary magnesium and potassium intake are associated with fewer OA symptoms, higher quality of life, and milder comorbid conditions in patients with knee OA, suggesting dietary magnesium and potassium may have beneficial effects on OA and could be used for knee OA management.
Subject(s)
Osteoarthritis, Knee , Aged , Humans , Knee Joint/pathology , Magnesium , Magnetic Resonance Imaging , Osteoarthritis, Knee/complications , Osteoarthritis, Knee/diagnosis , Osteoarthritis, Knee/epidemiology , Potassium , Quality of LifeABSTRACT
Objectives: We aimed to examine whether metformin (MET) use is associated with a reduced risk of total knee arthroplasty (TKA) and low severity of knee pain in patients with knee osteoarthritis (OA) and diabetes and/or obesity. Methods: Participants diagnosed with knee OA and diabetes and/or obesity from June 2000 to July 2019 were selected from the information system of a local hospital. Regular MET users were defined as those with recorded prescriptions of MET or self-reported regular MET use for at least 6 months. TKA information was extracted from patients' surgical records. Knee pain was assessed using the numeric rating scale. Log-binomial regression, linear regression, and propensity score weighting (PSW) were performed for statistical analyses. Results: A total of 862 participants were included in the analyses. After excluding missing data, there were 346 MET non-users and 362 MET users. MET use was significantly associated with a reduced risk of TKA (prevalence ratio: 0.26, 95% CI: 0.15 to 0.45, p < 0.001), after adjustment for age, gender, body mass index, various analgesics, and insurance status. MET use was significantly associated with a reduced degree of knee pain after being adjusted for the above covariates (ß: −0.48, 95% CI: −0.91 to −0.05, p = 0.029). There was a significantly accumulative effect of MET use on the reduced risk of TKA. Conclusion: MET can be a potential therapeutic option for OA. Further clinical trials are needed to determine if MET can reduce the risk of TKA and the severity of knee pain in metabolic-associated OA patients.
ABSTRACT
Methods of controlling Aspergillus flavus contamination in agro-products have attracted attention because of its impact on global food security. We previously reported that the natural cereal volatile heptanal could effectively inhibit A. flavus growth and showed great potential as a bio-preservative agent. In this study, the minimum inhibitory concentration and minimum fungicide concentration of heptanal could change the surface morphology of A. flavus spores, causing them to wrinkle and collapse. Transcriptomic analysis showed that heptanal treatment significantly changed the expression of several genes involved in cell wall and plasma damage, reactive oxygen species (ROS) accumulation, energy metabolism, AMPK-activated protein kinase, biosynthesis of unsaturated fatty acids, RNA degradation, and DNA replication. Heptanal-induced early apoptosis of A. flavus spores was characterized by decreased mitochondrial membrane potential, increased intracellular ROS production, and DNA fragmentation. This study provides new insight into the inhibitory mechanism of heptanal against A. flavus and points to its potential application as a bio-preservative. KEY POINTS: ⢠Heptanal can effectively inhibit A. flavus growth in cereal grains. ⢠The transcriptional changes in A. flavus spores exposed to heptanal were analyzed. ⢠The antifungal mechanism of heptanal against A. flavus was elucidated.
Subject(s)
Aldehydes , Aspergillus flavus , Antifungal Agents , Aspergillus flavus/genetics , Gene Expression Profiling , Spores, FungalABSTRACT
Chemical control of fungal spoilage of postharvest cereal grains is an important strategy for the management of grain storage. Here, the potential antifungal activity of 1-nonanol, a main component of cereal volatiles, against Aspergillus flavus was studied. The growth of A. flavus was completely inhibited by 0.11 and 0.20 µL/mL 1-nonanol at vapor and liquid contact phases, respectively. Metabolomic analysis identified 135 metabolites whose expression was significantly different between 1-nonanol-treated and untreated A. flavus. These metabolites were involved in the tricarboxylic acid cycle, amino acid biosynthesis, protein degradation and absorption, aminoacyl-tRNA biosynthesis, mineral absorption, and in interactions with ABC transporters. Biochemical validation confirmed the disruptive effect of 1-nonanol on A. flavus growth, as indicated by the leakage of intracellular electrolytes, decreased succinate dehydrogenase, mitochondrial dehydrogenase, and ATPase activity, and the accumulation of reactive oxygen species. We speculated that 1-nonanol could disrupt cell membrane integrity and mitochondrial function and might induce apoptosis of A. flavus mycelia. Simulated grain storage experiments showed that 1-nonanol vapor, at a concentration of 264 µL/L, completely inhibited A. flavus growth in wheat, corn, and paddy grain with an 18% moisture content. This study provides new insights into the antifungal mechanism of 1-nonanol against A. flavus, indicating that it has a promising potential as a bio-preservative to prevent fungal spoilage of postharvest grains. KEY POINTS: ⢠1-Nonanol showed higher antifungal activity against A. flavus. ⢠The antifungal mechanisms of 1-nonanol against A. flavus were revealed. ⢠1-Nonanol could damage cell membrane integrity and mitochondrial function.
Subject(s)
Antifungal Agents , Aspergillus flavus , Antifungal Agents/pharmacology , Fatty Alcohols , MetabolomicsABSTRACT
Aspergillus flavus is a notorious saprophytic fungus that compromises the quantity and quality of postharvest grains and produces carcinogenic aflatoxins. The natural compound hexanal disrupts cell membrane synthesis and mitochondrial function and induces apoptosis in A. flavus; here, we investigated the molecular mechanisms underlying these effects. The minimum inhibition and fungicidal concentration (MIC and MFC) of hexanal against A. flavus spores were 3.2 and 9.6 µL/mL, respectively. Hexanal exposure resulted in abnormal spore morphology and early spore apoptosis. These changes were accompanied by increased reactive oxygen species production, reduced mitochondrial membrane potential, and DNA fragmentation. Transcriptomic analysis revealed that hexanal treatment greatly altered the metabolism of A. flavus spores, including membrane permeability, mitochondrial function, energy metabolism, DNA replication, oxidative stress, and autophagy. This study provides novel insights into the mechanism underlying the antifungal activity of hexanal, suggesting that hexanal can be used an anti-A. flavus agent for agricultural applications. KEY POINTS: ⢠Hexanal exposure resulted in abnormal spore morphology. ⢠The apoptotic characteristics of A. flavus were induced after hexanal treatment. ⢠Hexanal could change the expression of key A. flavus growth-related genes.
Subject(s)
Aflatoxins , Aspergillus flavus , Aflatoxins/metabolism , Aldehydes , Antifungal Agents/metabolism , Antifungal Agents/pharmacology , Apoptosis , Mitochondria , Spores, Fungal/metabolismABSTRACT
Hexanal, a natural volatile organic compound, exerts antifungal activity against Aspergillus flavus; however, the mechanisms underlying these effects are unclear. In this study, we found that the growth of A. flavus mycelium was completely inhibited following exposure to 0.4 µL/mL hexanal (minimal inhibitory concentration). A detailed metabolomics survey was performed to identify changes in metabolite production by A. flavus cells after exposure to 1/2 the minimal inhibitory concentration of hexanal for 6 h, which revealed significant differences in 70 metabolites, including 20 upregulated and 50 downregulated metabolites. Among them, levels of L-malic acid, α-linolenic acid, phosphatidylcholine, D-ribose, riboflavin, D-mannitol, D-sorbitol, and deoxyinosine were significantly reduced. The metabolomics results suggest that the metabolites are mainly involved in the tricarboxylic acid cycle (TCA), ABC transport system, and membrane synthesis in A. flavus cells. Hexanal treatment reduced succinate dehydrogenase and mitochondrial dehydrogenase activity and stimulated superoxide anion and hydrogen peroxide accumulation in A. flavus mycelia. Increases in the electric conductivity and A260nm of the culture supernatant indicated cell membrane leakage. Therefore, hexanal appears to disrupt cell membrane synthesis, induce mitochondrial dysfunction, and increase oxidative stress in A. flavus mycelia. KEY POINTS: ⢠Metabolite changes of A. flavus mycelia were identified after hexanal treatment. ⢠Most differential metabolites were downregulated in hexanal-treated A. flavus. ⢠An antifungal model of hexanal against A. flavus was proposed.
Subject(s)
Aldehydes , Aspergillus flavus , Antifungal Agents/pharmacology , MetabolomicsABSTRACT
Non-structural carbohydrates (NSC) are essential substances for the tree growth and metabolism, and play an important role in environmental adaptation of trees. At temporal scale, NSC contents in trees have limited inter-annual variation, which could be attributed to the strategy of tree growth and carbon storage. Different factors influence NSC contents of trees in various climatic regions, which change substantially at the seasonal scale. At spatial scale, the variations of NSC content in trees show an insignificantly decreasing trend with the decreases of latitude at global and continental scales, which are mainly related to the hydrothermal gradients. The trend at regional scale is opposite because of the decrease of hydrothermal gradients and lower sample frequency. More sophisticated relations exist between the variations of NSC content in trees and altitudes, which are caused by species-specific characteristics and the variations of micro-habitat conditions. The variations of NSC content in trees at multiple spatial-temporal scales are generally determined by both biotic and abiotic factors, which are mainly dependent on the tradeoff among photosynthate production, respiratory depletion, and tree growth. Furthermore, the methods used for the determination of NSC content are different, which results in great uncertainties in comparing conclusions from different studies. The methods used for sample collection and measurement of NSC should be improved and unified to enhance the comparison among different studies. The NSC contents of trees in different age classes should be measured with all organs collected at multiple spatial-temporal scales. The underlying mechanisms, significance of NSC storage, transformation and allocation on tree growth and survival should be further discussed.