The MdVQ37-MdWRKY100 complex regulates salicylic acid content and MdRPM1 expression to modulate resistance to Glomerella leaf spot in apples.

Glomerella leaf spot (GLS), caused by the fungus Colletotrichum fructicola, is considered one of the most destructive diseases affecting apples. The VQ-WRKY complex plays a crucial role in the response of plants to biotic stresses. However, our understanding of the defensive role of the VQ-WRKY complex on woody plants, particularly apples, under biotic stress, remains limited. In this study, we elucidated the molecular mechanisms underlying the defensive role of the apple MdVQ37-MdWRKY100 module in response to GLS infection. The overexpression of MdWRKY100 enhanced resistance to C. fructicola, whereas MdWRKY100 RNA interference in apple plants reduced resistance to C. fructicola by affecting salicylic acid (SA) content and the expression level of the CC-NBS-LRR resistance gene MdRPM1. DAP-seq, Y1H, EMSA, and RT-qPCR assays indicated that MdWRKY100 inhibited the expression of MdWRKY17, a positive regulatory factor gene of SA degradation, upregulated the expression of MdPAL1, a key enzyme gene of SA biosynthesis, and promoted MdRPM1 expression by directly binding to their promotors. Transient overexpression and silencing experiments showed that MdPAL1 and MdRPM1 positively regulated GLS resistance in apples. Furthermore, the overexpression of MdVQ37 increased the susceptibility to C. fructicola by reducing the SA content and expression level of MdRPM1. Additionally, MdVQ37 interacted with MdWRKY100, which repressed the transcriptional activity of MdWRKY100. In summary, these results revealed the molecular mechanism through which the apple MdVQ37-MdWRKY100 module responds to GLS infection by regulating SA content and MdRPM1 expression, providing novel insights into the involvement of the VQ-WRKY complex in plant pathogen defence responses.

Identification of Hsp20 gene family in Malus domestica and functional characterization of Hsp20 class I gene MdHsp18.2b.

Heat shock protein 20 (Hsp20) is a small molecule heat shock protein that plays an important role in plant growth, development, and stress resistance. Little is known about the function of Hsp20 family genes in apple (Malus domestica). Here, we performed a genome-wide analysis of the apple Hsp20 gene family, and a total of 49 Hsp20s genes were identified from the apple genome. Phylogenetic analysis revealed that the 49 genes were divided into 11 subfamilies, and MdHsp18.2b, a member located in the CI branch, was selected as a representative member for functional characterization. Treatment with NaCl and Botryosphaeria dothidea (B. dothidea), the causal agent of apple ring rot disease, significantly induced MdHsp18.2b transcription level. Further analysis revealed that overexpressing MdHsp18.2b reduced the resistance to salt stress but enhanced the resistance to B. dothidea infection in apple calli. Moreover, MdHsp18.2b positively regulated anthocyanin accumulation in apple calli. Physiology assays revealed that MdHsp18.2b promoted H2O2 production, even in the absence of stress factors, which might contribute to its functions in response to NaCl and B. dothidea infection. Hsps usually function as homo- or heterooligomers, and we found that MdHsp18.2b could form a heterodimer with MdHsp17.9a and MdHsp17.5, two members from the same branch with MdHsp18.2b in the phylogenetic tree. Therefore, we identified 49 Hsp20s genes from the apple genome and found that MdHsp18.2b was involved in regulating plant resistance to salt stress and B. dothidea infection, as well as in regulating anthocyanin accumulation in apple calli.

Twist-1 is a PPARdelta-inducible, negative-feedback regulator of PGC-1alpha in brown fat metabolism.

Brown fat is specialized for energy expenditure, a process that is principally controlled by the transcriptional coactivator PGC-1alpha. Here, we describe a molecular network important for PGC-1alpha function and brown fat metabolism. We find that twist-1 is selectively expressed in adipose tissue, interacts with PGC-1alpha, and is recruited to the promoters of PGC-1alpha's target genes to suppress mitochondrial metabolism and uncoupling. In vivo, transgenic mice expressing twist-1 in the adipose tissue are prone to high-fat-diet-induced obesity, whereas twist-1 heterozygous knockout mice are obesity resistant. These phenotypes are attributed to their altered mitochondrial metabolism in the brown fat. Interestingly, the nuclear receptor PPARdelta not only mediates the actions of PGC-1alpha but also regulates twist-1 expression, suggesting a negative-feedback regulatory mechanism. These findings reveal an unexpected physiological role for twist-1 in the maintenance of energy homeostasis and have important implications for understanding metabolic control and metabolic diseases.

AMPK and PPARdelta agonists are exercise mimetics.

The benefits of endurance exercise on general health make it desirable to identify orally active agents that would mimic or potentiate the effects of exercise to treat metabolic diseases. Although certain natural compounds, such as reseveratrol, have endurance-enhancing activities, their exact metabolic targets remain elusive. We therefore tested the effect of pathway-specific drugs on endurance capacities of mice in a treadmill running test. We found that PPARbeta/delta agonist and exercise training synergistically increase oxidative myofibers and running endurance in adult mice. Because training activates AMPK and PGC1alpha, we then tested whether the orally active AMPK agonist AICAR might be sufficient to overcome the exercise requirement. Unexpectedly, even in sedentary mice, 4 weeks of AICAR treatment alone induced metabolic genes and enhanced running endurance by 44%. These results demonstrate that AMPK-PPARdelta pathway can be targeted by orally active drugs to enhance training adaptation or even to increase endurance without exercise.

The R2R3 MYB transcription factor MdMYB30 modulates plant resistance against pathogens by regulating cuticular wax biosynthesis.

BACKGROUND: The MYB transcription factor family is one of the largest transcriptional factor families in plants and plays a multifaceted role in plant growth and development. However, MYB transcription factors involved in pathogen resistance in apple remain poorly understood. RESULTS: We identified a new MYB family member from apple, and named it MdMYB30. MdMYB30 was localized to the nucleus, and was highly expressed in young apple leaves. Transcription of MdMYB30 was induced by abiotic stressors, such as polyethylene glycol and abscisic acid. Scanning electron microscopy and gas chromatograph-mass spectrometry analyses demonstrated that ectopically expressing MdMYB30 in Arabidopsis changed the wax content, the number of wax crystals, and the transcription of wax-related genes. MdMYB30 bound to the MdKCS1 promoter to activate its expression and regulate wax biosynthesis. MdMYB30 also contributed to plant surface properties and increased resistance to the bacterial strain Pst DC3000. Furthermore, a virus-based transformation in apple fruits and transgenic apple calli demonstrated that MdMYB30 increased resistance to Botryosphaeria dothidea. Our findings suggest that MdMYB30 plays a vital role in the accumulation of cuticular wax and enhances disease resistance in apple. CONCLUSIONS: MdMYB30 bound to the MdKCS1 gene promoter to activate its transcription and regulate cuticular wax content and composition, which influenced the surface properties and expression of pathogenesis-related genes to resistance against pathogens. MdMYB30 appears to be a crucial element in the formation of the plant cuticle and confers apple with a tolerance to pathogens.

Apple AP2/EREBP transcription factor MdSHINE2 confers drought resistance by regulating wax biosynthesis.

MAIN CONCLUSION: This study showed that AP2/EREBP transcription factor MdSHINE2 functioned in mediating cuticular permeability, sensitivity to abscisic acid (ABA), and drought resistance by regulating wax biosynthesis. Plant cuticular wax plays crucial roles in protecting plants from environmental stresses, particularly drought stress. Many enzymes and transcription factors involved in wax biosynthesis have been identified in plant species. In this study, we identified an AP2/EREBP transcription factor, MdSHINE2 from apple, which is a homolog of AtSHINE2 in Arabidopsis. MdSHINE2 was constitutively expressed at different levels in various apple tissues, and the transcription level of MdSHINE2 was induced substantially by abiotic stress and hormone treatments. MdSHINE2-overexpressing Arabidopsis exhibited great change in cuticular wax crystal numbers and morphology and wax composition of leaves and stems. Moreover, MdSHINE2 heavily influenced cuticular permeability, sensitivity to abscisic acid, and drought resistance.

miR-133a regulates adipocyte browning in vivo.

Prdm16 determines the bidirectional fate switch of skeletal muscle/brown adipose tissue (BAT) and regulates the thermogenic gene program of subcutaneous white adipose tissue (SAT) in mice. Here we show that miR-133a, a microRNA that is expressed in both BAT and SATs, directly targets the 3' UTR of Prdm16. The expression of miR-133a dramatically decreases along the commitment and differentiation of brown preadipocytes, accompanied by the upregulation of Prdm16. Overexpression of miR-133a in BAT and SAT cells significantly inhibits, and conversely inhibition of miR-133a upregulates, Prdm16 and brown adipogenesis. More importantly, double knockout of miR-133a1 and miR-133a2 in mice leads to elevations of the brown and thermogenic gene programs in SAT. Even 75% deletion of miR-133a (a1(-/-)a2(+/-) ) genes results in browning of SAT, manifested by the appearance of numerous multilocular UCP1-expressing adipocytes within SAT. Additionally, compared to wildtype mice, miR-133a1(-/-)a2(+/-) mice exhibit increased insulin sensitivity and glucose tolerance, and activate the thermogenic gene program more robustly upon cold exposure. These results together elucidate a crucial role of miR-133a in the regulation of adipocyte browning in vivo.

The histone demethylase Jhdm1a regulates hepatic gluconeogenesis.

Hepatic gluconeogenesis is required for maintaining blood glucose homeostasis; yet, in diabetes mellitus, this process is unrestrained and is a major contributor to fasting hyperglycemia. To date, the impacts of chromatin modifying enzymes and chromatin landscape on gluconeogenesis are poorly understood. Through catalyzing the removal of methyl groups from specific lysine residues in the histone tail, histone demethylases modulate chromatin structure and, hence, gene expression. Here we perform an RNA interference screen against the known histone demethylases and identify a histone H3 lysine 36 (H3K36) demethylase, Jhdm1a, as a key negative regulator of gluconeogenic gene expression. In vivo, silencing of Jhdm1a promotes liver glucose synthesis, while its exogenous expression reduces blood glucose level. Importantly, the regulation of gluconeogenesis by Jhdm1a requires its demethylation activity. Mechanistically, we find that Jhdm1a regulates the expression of a major gluconeogenic regulator, C/EBPα. This is achieved, at least in part, by its USF1-dependent association with the C/EBPα promoter and its subsequent demethylation of dimethylated H3K36 on the C/EBPα locus. Our work provides compelling evidence that links histone demethylation to transcriptional regulation of gluconeogenesis and has important implications for the treatment of diabetes.

Post-Harvest Application of Nanoparticles of Titanium Dioxide (NPs-TiO2) and Ethylene to Improve the Coloration of Detached Apple Fruit.

In this study, we analyzed the effects of treatments with titanium dioxide nanoparticles (NPs-TiO2) and ethylene on anthocyanin biosynthesis and reactive oxygen species (ROS) metabolism during light exposure in ripe 'red delicious' apples. Both treatments led to improved anthocyanins biosynthesis in detached mature apples, while the NPs-TiO2 had less impact on the fruit firmness, TSS, TA, and TSS/TA ratio. Furthermore, the effects of both treatments on the expression of anthocyanin-related enzymes and transcription factors in the apple peel were evaluated at the gene level. The differentially expressed genes induced by the two treatments were highly enriched in the photosynthesis and flavonoid biosynthesis pathways. The expression of structural genes involved in anthocyanin biosynthesis and ethylene biosynthesis was more significantly upregulated in the ethylene treatment group than in the NPs-TiO2 treatment group, and the opposite pattern was observed for the expression of genes encoding transcription factors involved in plant photomorphogenesis pathways. In addition, the ROS levels and antioxidant capacity were higher and the membrane lipid peroxidation level was lower in fruit in the NPs-TiO2 treatment group than in the ethylene treatment group. The results of this study reveal differences in the coloration mechanisms induced by NPs-TiO2 and ethylene in apples, providing new insights into improving the color and quality of fruits.

A brown fat-enriched adipokine, ASRA, is a leptin receptor antagonist that stimulates appetite.

The endocrine control of food intake remains incompletely understood, and whether the leptin receptor-mediated anorexigenic pathway in the hypothalamus is negatively regulated by a humoral factor is unknown. Here we identify an appetite-stimulating factor - ASRA - that acts as a leptin receptor antagonist. ASRA encodes an 8 kD protein that is abundantly and selectively expressed in adipose tissue and to a lesser extent, in liver, and is upregulated during fasting and cold. ASRA protein associates with autophagosomes and its secretion is induced by energy deficiency. Overexpression of ASRA in mice attenuates leptin receptor signaling leading to elevated blood glucose and development of severe hyperphagic obesity, whereas either adipose- or liver-specific ASRA knockout mice display increased leptin sensitivity, improved glucose homeostasis, reduced food intake, and resistance to high fat diet-induced obesity. Furthermore, ASRA is indispensable for cold-evoked feeding response. Recombinant ASRA (rASRA) protein binds to leptin receptor and suppresses leptin receptor signaling in cultured cells. In vivo, rASRA promotes food intake and increases blood glucose in a leptin receptor signaling-dependent manner. Our studies collectively show that ASRA, acting as a peripheral signal of energy deficit, stimulates appetite and regulates glucose metabolism by antagonizing leptin receptor signaling, thus revealing a previously unknown endocrine mechanism that has important implications for our understanding of leptin resistance.

Effects of cellulose nanofibrils treatment on antioxidant properties and aroma of fresh-cut apples.

Horticultural products tend to deteriorate during postharvest storage and processing. In this study, cellulose nanofibers (CNFs) were prepared from wood to investigate the effects of CNF treatment on the storage quality, aroma composition, and antioxidant system of fresh-cut apple (Malus domestica) wedges. Compared with control treatment, CNF coating treatment significantly improved the appearance of apple wedges; reduced the decay rate of apple wedges; and delayed the decline in weight loss, firmness, and titratable acid during storage. Gas chromatography-mass spectrometry showed that CNF treatment could maintain the aroma components of apple wedges (stored for 4 days). Further investigations showed that CNF treatment increased the antioxidant system level and decreased reactive oxygen species content and membrane lipid peroxidation level of apple wedges. Overall, this study showed that CNF coating could effectively maintain the quality of fresh-cut apples during cold storage.

The KRAB Domain-Containing Protein ZFP961 Represses Adipose Thermogenesis and Energy Expenditure through Interaction with PPARα.

Adipose thermogenesis plays a pivotal role in whole-body metabolic homeostasis. Although transcriptional mechanisms that promote thermogenesis are extensively studied, the negative regulatory network is still poorly understood. Here, a Krüppel-associated box (KRAB) domain-containing zinc finger protein, ZFP961, as a potent repressor of the thermogenic program is identified. ZFP961 expression is induced by cold and ß3-adrenergic agonist in adipose tissue. ZFP961 represses brown fat-selective gene expression and mitochondrial respiration without any effect on general adipogenesis in cultured adipocytes. Adipose-specific knockdown and overexpression of ZFP961 produce remarkable and opposite phenotypes of white fat remodeling. ZFP961 knockout mice display robust inguinal white adipose tissue browning, which is abolished by reexpression of full-length ZFP961, but not by KRAB domain-deleted ZFP961 mutant. ZFP961-deficient mice are cold tolerant and resistant to high-fat diet-induced obesity, hyperglycemia, and hepatic steatosis. ZFP961 suppresses thermogenic gene expression by directly interacting with PPARα and blocking its transcriptional activity, which can be completely negated by the PPARα agonist. The findings uncover ZFP961 as a critical physiological brake that limits adipose thermogenesis and provides insights into the regulatory mechanisms that maintain energy balance and tissue homeostasis.

Study on Forming Law and Penetration of a Spherical Cone Composite Structure Liner Based on the Explosion Pressure-Coupling Constraint Principle.

The liner is an important part of shaped charge. In this paper, the spherical cone composite structure liner composed of a spherical missing body and truncated cone (hereinafter referred to as the SCS liner) is studied. The SCS liner is made of copper. Based on this, a shaped charge structure based on the explosion pressure-coupling constraint principle is designed, filling an 8701 explosive (RDX-based explosive). Through pulse X-ray tests, numerical simulation, and static explosion tests, the significance of the detonation pressure-coupling constraint principle, as well as the forming law and penetration efficiency of the SCS liner are studied. The results show that in the pulsed X-ray test, a split jet with high velocity is formed in the SCS liner. The explosion pressure-coupling constraint principle delays the attenuation of the internal explosion pressure and improves the shape of jet. After the SCS liner is selected, the penetration depth is increased by 70.38%. The average head velocity of the explosive charge jet is 7594.81 m/s. The diameter of the hole formed by the jet of the explosive charge is 20.33 mm. The hole expands inside, and the perforation depth is 178.87 mm. The numerical simulation is in good agreement with the test.

Cellulose Nanofibers Extracted From Natural Wood Improve the Postharvest Appearance Quality of Apples.

To prolong the shelf life of perishable food with a simple and environmentally friendly postharvest preservation technology is one of the global concerns. This study aimed to explore the application value of biological macromolecule natural cellulose nanofibers (CNFs) in extending the postharvest fruit shelf life. In this study, 0.5% (wt%) CNFs were prepared from natural wood and coated on the surface of early-ripening apple fruits. After 10 days of storage at room temperature, the results revealed that the shelf life of apple fruits with CNF coating was significantly prolonged, and the fruit appearance quality improved. The invisible network structure of CNFs in the fruit epidermis was observed under an atomic force microscope (AFM). The gas chromatography and mass spectrometry (GC-MS) analysis showed that CNFs significantly promoted the formation of epidermal wax, especially fatty alcohols, during storage. In addition, the CNFs remarkably promoted the upregulation of genes related to the synthesis of cuticular wax of apple. In conclusion, this study provides an environmentally sustainable nanomaterial for post-harvest preservation of horticultural products, and also provides a new insight into the effect of CNFs on postharvest storage of apple fruits.

A brown fat-enriched adipokine Adissp controls adipose thermogenesis and glucose homeostasis.

The signaling mechanisms underlying adipose thermogenesis have not been fully elucidated. Particularly, the involvement of adipokines that are selectively expressed in brown adipose tissue (BAT) and beige adipocytes remains to be investigated. Here we show that a previously uncharacterized adipokine (UPF0687 protein / human C20orf27 homolog) we named as Adissp (Adipose-secreted signaling protein) is a key regulator for white adipose tissue (WAT) thermogenesis and glucose homeostasis. Adissp expression is adipose-specific and highly BAT-enriched, and its secretion is stimulated by ß3-adrenergic activation. Gain-of-functional studies collectively showed that secreted Adissp promotes WAT thermogenesis, improves glucose homeostasis, and protects against obesity. Adipose-specific Adissp knockout mice are defective in WAT browning, and are susceptible to high fat diet-induced obesity and hyperglycemia. Mechanistically, Adissp binds to a putative receptor on adipocyte surface and activates protein kinase A independently of ß-adrenergic signaling. These results establish BAT-enriched Adissp as a major upstream signaling component in thermogenesis and offer a potential avenue for the treatment of obesity and diabetes.

PPARs and the complex journey to obesity.

Obesity and the related disorders of dyslipidemia and diabetes (components of syndrome X) have become global health epidemics. Over the past decade, the elucidation of key regulators of energy balance and insulin signaling have revolutionized our understanding of fat and sugar metabolism and their intimate link. The three 'lipid-sensing' peroxisome proliferator-activated receptors (PPAR-alpha, PPAR-gamma and PPAR-delta) exemplify this connection, regulating diverse aspects of lipid and glucose homeostasis, and serving as bona fide therapeutic targets. With molecular underpinnings now in place, new pharmacologic approaches to metabolic disease and new questions are emerging.

Study on the effect of simulated nuclear industry working conditions on the explosion severity parameters of zirconium powder and the explosion mechanism.

Explosion caused by zirconium powder was revealed as one of main reasons in accidents happened in reprocessing of spent fuel in nuclear industry. It is urgent to study the explosion severity characteristic of zirconium dust cloud due to the great harm of its explosion. According to the equipment used in the actual post-treatment process in nuclear industry, the 20L cylindrical explosion equipment as a scale model was manufactured as the experimental device. The experimental results showed that Pmax and (dp/dt)max increased at first and then decreased with the increase of concentration. Small zirconium particles produced larger value of explosion severity parameters. Interestingly, initial temperature had no significant effect on Pmax of zirconium powder. However, the value of (dp/dt)max was strongly dependent on the initial temperature. Additionally, the oxidation degree of zirconium dust and temperature generated during explosion were studied by means of oxygen content and crystal form of explosion products. The study found that the particles develop toward spheroidization and its size became smaller, indicating that zirconium particles combustion is a heterogeneous shrinking core process. Under the condition of constant mass, increased number of ZrO2 particles leads to enlarged particle total surface area, increasing the amount of radioactive material released.

MdCER2 conferred to wax accumulation and increased drought tolerance in plants.

Drought can activate many stress responses in plant growth and development, including the synthesis of epidermal wax and the induction of abscisic acid (ABA), and increased wax accumulation will improve plant drought resistance. Therefore, an examination of wax biosynthesis genes could help to better understand the molecular mechanism of environmental factors regulating wax biosynthesis and the wax associated stress response. Here, we identified the MdCER2 gene from the 'Gala' (Malus× domestica Borkh.) variety of domestic apple, which is a homolog of Arabidopsis AtCER2. It possesses a transferase domain and the protein localizes on the cell membrane. The MdCER2 gene was constitutively expressed in apple tissues and was induced by drought treatment. Finally, we transformed the MdCER2 gene into Arabidopsis to identify its function, and found ectopic expression of MdCER2 promoted accumulation of cuticular wax in both leaves and stems, decreased water loss and permeability in leaves, increased lateral root number, changed plant ABA sensitivity, and increased drought resistance.

Chemical and microbiological responses of heavy metal contaminated sediment subject to washing using humic substances.

Washing of contaminated soils or sediments using humic substances (HS) extracted either from source-rich materials or compost has been tested effective to remove various heavy metals. Nevertheless, the remaining chemical fractionation of metals and post-washing biological responses were not discussed in previous research. In this study, we used a HS extracted from green waste compost to wash off Cd, As, and Ni from a contaminated sediment, and evaluated the washing effect on sediment microbes by measuring a series of indexes with regard to microbial biomass and enzyme activities. Results showed that HS washing was more effective in removing the cationic metals Cd and Ni than the anionic metal As. The highest HS dose of 2000 mg L-1 resulted in 24.5-, 33.1-, and 12-fold increases of removal for Cd, Ni, and As, respectively. The remaining Cd and As were found to migrate to less stable fractions, whereas the remaining Ni was dominantly found in the residual fraction. Increases of metal removal efficiency, microbial biomass, and dehydrogenase activity were found to correlate with the increase of HS concentrations. Increasing doses of HS slightly altered sediment pH to the lower range but did not cause any significant effect on microbial activities. The study proves that HS washing is indeed a more environmental-friendly strategy than many existing washing agents which have exerted various side effects on soil properties.

STOML2 as a novel prognostic biomarker modulates cell proliferation, motility and chemo-sensitivity via IL6-Stat3 pathway in head and neck squamous cell carcinoma.

STOML2 (Stomatin-like protein 2) is up-regulated and acts as an oncogenic protein in multiple cancers. However, the role and regulatory mechanism of STOML2 in head and neck squamous cell carcinoma remain unclear. Here, we found that STOML2 is overexpressed and indicates poor outcomes in HNSCC. In addition, the expression of STOML2 correlates positively with T stage, lymph node metastasis and recurrence. Reduced STOML2 dramatically inhibits cell proliferation, colony formation and motility of HNSCC cells in vitro. Furthermore, the sensitivity of HNSCC cells towards cisplatin is obviously improved in STOML2-silencing cells. Subsequent studies suggest that STOML2 could regulate the expression of IL6 transcriptionally and then further induce the phosphorylation of Tyr705 residue of Stat3, whose activation plays a critical role in HNSCC. Taken together, these results for the first time demonstrate that STOML2 promotes HNSCC progression through activating IL6-Stat3 pathway and provide a promise for diagnosis and treatment for HNSCC.