4-Hydroxy Pyridones from Heterologous Expression and Cultivation of the Native Host.

4-Hydroxy pyridones are a class of fungi-derived polyketide-nonribosomal peptide products featuring a core of 4-hydroxy-2-pyridone which have a wide range of biological activities. Genome mining of in-house strains using polyketide synthase-nonribosomal peptide synthase as a query identified an endophyte Tolypocladium sp. 49Y, which possesses a potential 4-hydroxy pyridone biosynthetic gene cluster. Heterologous expression in Aspergillus oryzae NSAR1 revealed that this gene cluster is functional and able to produce a rare type of 4-hydroxy pyridones called tolypyridones (compounds 3 and 4). Tolypocladium sp. 49Y was grown in a variety of media which led to the isolation of six 4-hydroxy pyridones (5-10) and one pyrrolidone (11) from a rice culture, and compounds 3 and 9 showed antifungal activity. These latter compounds are different from those obtained by heterologous expression. This study shows that both heterologous expression and cultivation of the native host are complementary approaches to discover new natural products.

New phenylpropanoid allopyranosides from the rhizomes of Cimicifuga dahurica.

Five new phenylpropanoid allopyranosides (1-5), along with five known compounds (6-10) were isolated from the rhizomes of Cimicifuga dahurica. Their structures were established by means of spectroscopic analyses and chemical methods, as well as comparison with literatures. The anti-inflammatory activities of all isolates were evaluated. Compounds 6, 9 and 10 exhibited inhibitory effects on PGE2 production in LPS stimulated RAW 264.7 macrophages with IC50 values of 19.72, 6.33 and 39.90 µM, respectively.

New lignans attenuating cognitive deterioration of Aß transgenic flies discovered in Acorus tatarinowii.

Five new lignan racemates, (±)-tatarinoid D-H (1-5), and three known analogues (6-8) were isolated from the rhizomes of Acorus tatarinowii. Their structures were established by 1D, 2D-NMR, HR-MS, IR and optical spectral data. Among them, 1 and 6-8 can alleviate the cognitive deterioration of Aß transgenic flies.

Two new bisabolane sesquiterpenoids from Curcuma longa.

Two new bisabolane derivatives were isolated from the rhizome of Curcuma longa L., and their structures were characterized by analyzing spectroscopic data especially 1D- and 2D-NMR spectra. Relative configurations of two compounds were determined by NOESY correlations.

Validity and reliability of a wearable blood flow restriction training device for arterial occlusion pressure assessment.

Purpose: The blood flow restriction (BFR) training is an effective approach to promoting muscle strength, muscle hypertrophy, and regulating the peripheral vascular system. It is recommended to use to the percentage of individual arterial occlusion pressure (AOP) to ensure safety and effectiveness. The gold standard method for assessing arterial occlusive disease is typically measured using Doppler ultrasound. However, its high cost and limited accessibility restrict its use in clinical and practical applications. A novel wearable BFR training device (Airbands) with automatic AOP assessment provides an alternative solution. This study aims to examine the reliability and validity of the wearable BFR training device. Methods: Ninety-two participants (46 female and 46 male) were recruited for this study. Participants were positioned in the supine position with the wearable BFR training device placed on the proximal portion of the right thigh. AOP was measured automatically by the software program and manually by gradually increasing the pressure until the pulse was no longer detected by color Doppler ultrasound, respectively. Validity, inter-rater reliability, and test-retest reliability were assessed by intraclass correlation coefficients (ICC) and Bland-Altman analysis. Results: The wearable BFR training device demonstrated good validity (ICC = 0.85, mean difference = 4.1 ± 13.8 mmHg [95% CI: -23.0 to 31.2]), excellent inter-rater reliability (ICC = 0.97, mean difference = -1.4 ± 6.7 mmHg [95% CI: -14.4 to 11.7]), and excellent test-retest reliability (ICC = 0.94, mean difference = 0.6 ± 8.6 mmHg [95% CI: -16.3 to 17.5]) for the assessment of AOP. These results were robust in both male and female subgroups. Conclusion: The wearable BFR training device can be used as a valid and reliable tool to assess the AOP of the lower limb in the supine position during BFR training.

[Carbon footprint of major grain crops in the middle and lower reaches of the Yangtze River during 2011-2020]. / 2011­2020年长江中下游地区主要粮食作物生产碳足迹.

The middle and lower reaches of the Yangtze River is one of main grain production areas in China, which is of great significance to food security. Understanding the carbon footprint of major grain crop production is helpful to develop high-yield and low-carbon agriculture. Based on the data of yield, sown area and farmland production input of main grain crops (rice, wheat and maize) in six provinces (Jiangsu, Anhui, Jiangxi, Hubei, Hunan, and Zhejiang) in the middle and lower reaches of the Yangtze River from 2011 to 2020, we estimated carbon footprint in the production of the three grain crops. The results showed that from 2011 to 2020, yield per unit area, planting area, and total yield of rice, wheat and maize were the highest in Jiangsu Province. In terms of area-scaled carbon footprint, rice in the middle and lower reaches of the Yangtze River had the highest area-scaled carbon footprint, with an average of 2.0 t CE·hm-2, followed by wheat and maize. The area-scaled carbon footprint of the three staple crops was increasing. In terms of yield-scaled carbon footprint, rice was the highest, with an average of 0.8 kg CE·kg-1, followed by wheat and maize. In terms of carbon input structure, irrigation electricity, chemical fertilizers and pesticides accounted for a relatively high proportion. Irrigation electricity accounted for 35.0%, 36.3%, and 33.2% of the total carbon input of rice, wheat and maize, respectively. Chemical fertilizers accounted for 28.8%, 32.5%, and 32.5%, respectively, while pesticides accounted for 24.2%, 13.3% and 11.5%, respectively. In terms of carbon efficiency, maize had the highest (3.9 kg·kg-1 CE), followed by rice and wheat. With the green development of agriculture, carbon emission in the production of major grain crops in the middle and lower reaches of the Yangtze River could be reduced by improving irrigation efficiency, fertilizer utilization efficiency, pesticide utilization efficiency and mechanized operation efficiency, as well as diversification of straw returning, cultivation of new varieties and policy leverage.

Non-invasive Assessment of Axillary Lymph Node Metastasis Risk in Early Invasive Breast Cancer Adopting Automated Breast Volume Scanning-Based Radiomics Nomogram: A Multicenter Study.

OBJECTIVE: The aim of the work described here was to develop a non-invasive tool based on the radiomics and ultrasound features of automated breast volume scanning (ABVS), clinicopathological factors and serological indicators to evaluate axillary lymph node metastasis (ALNM) in patients with early invasive breast cancer (EIBC). METHODS: We retrospectively analyzed 179 ABVS images of patients with EIBC at a single center from January 2016 to April 2022 and divided the patients into training and validation sets (ratio 8:2). Additionally, 97 ABVS images of patients with EIBC from a second center were enrolled as the test set. The radiomics signature was established with the least absolute shrinkage and selection operator. Significant ALNM predictors were screened using univariate logistic regression analysis and further combined to construct a nomogram using the multivariate logistic regression model. The receiver operating characteristic curve assessed the nomogram's predictive performance. DISCUSSION: The constructed radiomics nomogram model, including ABVS radiomics signature, ultrasound assessment of axillary lymph node (ALN) status, convergence sign and erythrocyte distribution width (standard deviation), achieved moderate predictive performance for risk probability evaluation of ALNs in patients with EIBC. Compared with ultrasound, the nomogram model was able to provide a risk probability evaluation tool not only for the ALNs with positive ultrasound features but also for micrometastatic ALNs (generally without positive ultrasound features), which benefited from the radiomics analysis of multi-sourced data of patients with EIBC. CONCLUSION: This ABVS-based radiomics nomogram model is a pre-operative, non-invasive and visualized tool that can help clinicians choose rational diagnostic and therapeutic protocols for ALNM.

Nutrient modification of the innate immune response: a novel mechanism by which saturated fatty acids greatly amplify monocyte inflammation.

OBJECTIVE: Monocyte/macrophage inflammation is an important contributor to diabetes and cardiovascular disease. Studies have suggested saturated fatty acids (SFA) induce monocyte inflammation in a Toll-like receptor-4-dependent manner, but recent data suggest SFA do not directly interact with Toll-like receptor-4. The present study tests the novel hypothesis that metabolism of SFA cooperatively amplifies Toll-like receptor-4-mediated inflammation. METHODS AND RESULTS: THP-1 monocytes exposed to 100 micromol/L SFA in vitro for 16 hours followed by 1 ng/mL lipopolysaccharide demonstrated enhanced IL-6 and IL-8 mRNA and protein expression (approximately 3-fold higher than the sum of individual responses to SFA and lipopolysaccharide). SFA had similar effects on THP-1 macrophages and primary human monocytes. This amplified lipopolysaccharide response could be blocked by inhibition of SFA metabolism to ceramide and restored by cell-permeable ceramide. Both SFA and ceramide activated PKC-zeta and the mitogen-activated protein kinases Erk, JNK, and p38. Inhibition of these pathways prevented the SFA-induced increase in cytokine expression. CONCLUSIONS: These results provide evidence for potent amplification of monocyte/macrophage innate immune responses by a novel pathway requiring metabolism of SFA to ceramide and activation of PKC-zeta/mitogen-activated protein kinases. These findings demonstrate how nutrient excess may modulate innate immune system activation and possibly contribute to development of diabetes and cardiovascular disease.

[Expression of orphanin in adenomyosis and its relationship with dysmenorrhea].

OBJECTIVE: To study the expression of nociceptin in adenomyosis tissue and understand its relationship with the severity of dysmenorrhea. METHODS: The myometrial specimens were collected from 55 patients undergoing hysterectomy at our hospital during December 2007 and June 2008. Their mean age was 41 - 52 years old. There were 34 adenomyosis patients in case group and 21 other patients in control group. Immunohistochemical staining was employed to detect nociceptin in eutopic endometrium and ectopic endometrial tissues in case group and normal endometrium and myometrial tissues in control group. RESULTS: The expression of nociceptin was significantly higher in the eutopic endometrial tissue (7.1 ± 1.7) of case group than those in endometrial (2.7 ± 2.0) and myometrial tissues of control group (P < 0.05); The expression of nociceptin was higher in the eutopic endometrial tissue (7.4 ± 1.5) of dysmenorrhea group than that of non-dysmenorrhea group (5.0 ± 1.2) in case group (P < 0.05); The expression of nociceptin in eutopic endometrium and myometrium was the highest in severe dysmenorrhea group (8.4 ± 1.3). And the non-dysmenorrhea and mild dysmenorrheal groups had no significant differences [(5.0 ± 1.2) vs (6.8 ± 1.4)]. And it decreased gradually in moderate dysmenorrhea, mild dysmenorrhea and non-dysmenorrhea groups. CONCLUSION: A high expression of nociceptin in adenomyosis may be one of the casual factors of dysmenorrhea. The severity of dysmenorrhea is positively correlated with the expression of nociceptin in eutopic endometrial tissue in case group (r = 0.515, P = 0.034) and ectopic endometrium tissue. And the endometrial expression of nociceptin may be monitored dynamically to track the development of adenomyosis.

MEK1/2 Inhibitor (GDC0623) Promotes Osteogenic Differentiation of Primary Osteoblasts Inhibited by IL-1ß through the MEK-Erk1/2 and Jak/Stat3 Pathways.

OBJECTIVE: We evaluated the effects and mechanisms of GDC0623 on osteogenic differentiation of osteoblasts induced by IL-1ß. Methodology. Osteoblasts were treated with 20 ng/ml IL-1ß and 0.1 µM GDC0623. Cell proliferation levels were evaluated by the cell counting kit 8 (CCK8), EdU assay, and western blotting [proliferating cell nuclear antigen (PCNA) and Cyclin D1]. Osteoblasts were cultured in an osteogenic induction medium for 1-3 weeks after which their differentiations were assessed by alkaline phosphatase (ALP) staining, Alizarin Red staining, calcium concentration, immunocytochemistry staining, real-time quantitative PCR (RT-qPCR), and immunofluorescence staining. The osteogenesis-associated mechanisms were further evaluated by western blotting using appropriate antibodies. RESULTS: Relative to the control group, IL-1ß induced the rapid proliferation of osteoblasts and suppressed their osteogenic differentiations by upregulating the activities of MEK-Erk1/2 as well as Jak-Stat3 pathways and by elevating MMP13 and MMP9 levels. However, blocking of the MEK-Erk1/2 signaling pathway by GDC0623 treatment reversed these effects. CONCLUSION: Inhibition of Jak-Stat3 pathway by C188-9 downregulated the expression levels of MMP9 and MMP13, activated MEK-Erk1/2 pathway, and inhibited osteogenic differentiation.

Pioglitazone inhibits the expression of inflammatory cytokines from both monocytes and lymphocytes in patients with impaired glucose tolerance.

OBJECTIVE: The current study determines whether pioglitazone (PIO) therapy reduces both monocyte and lymphocyte inflammatory activity and their ability to induce inflammation in other tissues. METHODS AND RESULTS: Monocyte and lymphocyte cytokine gene and protein expression of interleukin (IL)-6 were first shown to be greater in subjects with impaired glucose tolerance (IGT) than in subjects with normal glucose tolerance. Sixty-six IGT subjects were then randomized to 4,5 months of placebo or PIO therapy. After receiving PIO, subjects had lower triglycerides and higher HDL cholesterol (P<0.05) than did subjects receiving placebo. Monocyte gene and protein expression of IL-1 beta, IL-6, and IL-8 (and IL-2, IL-6 and IL-8 from lymphocytes) was significantly lower after PIO therapy in the resting state, as well as after lipopolysaccharide (LPS) stimulation (P<0.05 for all). Moreover, IL-6, IL-8, and MCP-1 gene expression were decreased by nearly 50% in human adipocytes exposed to conditioned media from monocytes or lymphocytes from PIO treated subjects. CONCLUSIONS: These results demonstrate that PIO therapy in IGT can reduce proinflammatory gene and protein expression from both monocytes and lymphocytes. This intervention also reduces the inflammatory cross-talk between these immune cells and adipose tissue, which could in turn contribute to the metabolic improvements resulting from PIO therapy.

Two new ursane-type nortriterpenes from Lonicera macranthoides and their iNOS-inhibitory activities.

The flower buds of Lonicera macranthoides (Shan Yin-Hua), represent an important traditional Chinese medicine and food ingredient. A phytochemical investigation of the 70% EtOH extract of the flower buds of L. macranthoides resulted in the isolation of 12 triterpenoids (1-12), including two new ursane-type nortriterpenes, 2α, 24-dihydroxy-23-nor-ursolic acid (1) and 2α, 4α-dihydroxy-23-nor-ursolic acid (2). Their structures were established by multiple spectroscopic methods and comparison with literature data. All isolated compounds were evaluated for their anti-inflammatory effects in LPS-activated RAW264.7 cells. Compounds 1 and 2 exhibited inhibitory effects on iNOS at the concentration of 30 µmol·L-1.

Discovery of the mechanisms and major bioactive compounds responsible for the protective effects of Gualou Xiebai Decoction on coronary heart disease by network pharmacology analysis.

BACKGROUND: Gualou Xiebai decoction (GLXB), a multi-component herbal formula, has been widely used to treat coronary heart disease (CHD) in China for centuries. Several studies have revealed part of its pharmacological activities, whereas its active compounds and mechanisms of action are still unknown because of its complex composition. PURPOSE: Discover the major active compounds and the pharmacological mechanisms of GLXB by network pharmacology methods. METHODS: The main candidate target network was constructed by predicting targets of absorbable chemical compounds of GLXB, collecting therapeutic targets of cardiovascular drugs, constructing target network and layers of screening. Community detection and edge-betweenness calculation were applied to analyze the main candidate target network. Cell viability test, Western blot and flow cytometry were performed to validate the predicted results in cardiomyocytes hypoxia/reoxygenation model. RESULTS: Five clusters and eight cross-talk targets were found in the main candidate target network. Their functions combined together might explain the multifunctional role of GLXB against CHD. Among the cross-talk targets, ESR1 (Estrogen receptor alpha, ERα) and MAPK14 (Mitogen-activated protein kinase 14, p38) were both drug targets and therapeutic targets whose interaction exhibited the greatest edge-betweenness value, suggesting their crucial role in the protective effect of GLXB. The compounds targeting on ESR1 and MAPK14 were identified as apigenin and 25S-macrostemonoside P respectively which were regard as the major bioactive compounds. The predicted results including the major bioactive compounds, their targets and the synergic effects between them were validated. CONCLUSION: This study screened out major bioactive compounds from GLXB and offered a new understanding of the protection mechanism of GLXB against CHD by network pharmacology method and provides a combination strategy to explore mechanisms of action of multi-component drugs from a holistic perspective.

Phenolic acids and their glycosides from the rhizomes of Cimicifuga dahurica.

Phytochemical study on rhizomes of Cimicifuga dahurica resulted in the isolation of nine new neolignan and phenylpropanoid glycosides, cimicifugasides A-E (1, 2, 7-9), cimicifugamides B-D (3-5), shomaside G (6) along with four known compounds (10-13). Their structures were identified by extensive spectroscopic analyses (1D-, 2D-NMR, MS, CD, IR, UV) and chemical methods. Their anti-inflammatory potentials were evaluated by measuring their effects on PGE2 production of LPS-stimulated RAW264.7 cells, and compounds 12 and 13 showed moderate anti-inflammatory activities.

Discovery of cardio-protective constituents of Gualou Xiebai Decoction, a classical traditional Chinese medicinal formula.

BACKGROUD: Finding effective compounds of TCMs has always been the basis for achieving marker-based quality control which is currently most widely used quality control strategy. Gualou Xiebai Decoction (GLXB), a classical TCM formula, is recorded and proven as a therapy for curing coronary heart disease but the effective constituents are unidentified and the substantial basis of the therapeutic effects is not clear. PURPOSE: The present research is an investigation on the chemistry of this formula aiming at finding and precisely identifying effective compounds. STUDY DESIGN AND METHODS: This research started with screening for effective fractions of GLXB by rat myocardial infarction model and H9c2 cell hypoxia/reoxygenation model, then compounds in effective fractions were isolated and identified by phytochemical and spectroscopic methods. The cardio-protective activities of the compounds were tested in vitro and one of the effective compounds was taken as example to investigate the mechanisms. RESULTS: The water-insoluble parts of GLXB were identified as effective parts in both in vitro and in vivo experiments. Systematic isolation of compounds in the effective fractions resulted in the isolation of 34 compounds including 7 new compounds, whereas 8 compounds were effective in protecting H9c2 cells against hypoxia/reoxygenation injury. One of the effective compounds, macrostemonoside P (MP) possibly exerted its effect by activating RISK pathway and attenuating apoptosis. CONCLUSION: An array of effective constituents of GLXB were discovered, and discovery of these compounds contributed to elucidating the substantial basis for the therapeutic effects of this formula, and provides fundaments for establishing Q-markers for further reliable quality control of GLXB.

Gualou Xiebai Decoction, a Traditional Chinese Medicine, Prevents Cardiac Reperfusion Injury of Hyperlipidemia Rat via Energy Modulation.

Background: Gualou Xiebai Decoction (GLXB) is a classic prescription of Chinese medicine used for the treatment of cardiac problems. The present study was designed to explore the effect and mechanism of GLXB on ischemia/reperfusion (I/R) induced disorders in myocardial structure and function, focusing on the regulation of energy metabolism and the RhoA/ROCK pathway. Methods: After hyperlipidemic rat model was established by oral administration of high fat diet, the rats were treated with GLXB for 6 weeks and subjected to 30 min occlusion of the left anterior descending coronary artery (LADCA) followed by 90 min reperfusion to elicit I/R challenge. Myocardial infarct size was assessed by Evans blue-TTC staining. Myocardial blood flow (MBF) and cardiac function were evaluated. Enzyme-linked immunosorbent assay was performed to examine the content of ATP, ADP, AMP, CK, CK-MB, LDH, cTnT, cTnI, and IL-6. Double staining of F-actin and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling was conducted to assess myocardial apoptosis. Expressions of ATP synthase subunit δ (ATP 5D), and RhoA and ROCK were determined by Western blotting. Results: Administration with GLXB at high dose for 6 weeks protected heart against I/R-induced MBF decrease, myocardial infarction and apoptosis, ameliorated I/R-caused impairment of cardiac function and myocardial structure, restored the decrease in the ratio of ADP/ATP and AMP/ATP, and the expression of ATP 5D with inhibiting the expression of RhoA and ROCK. Conclusions: Treatment with GLXB effectively protects myocardial structure and function from I/R challenge, possibly via regulating energy metabolism involving inactivation of RhoA/ROCK signaling pathway.

Elevated concentrations of nonesterified fatty acids increase monocyte expression of CD11b and adhesion to endothelial cells.

OBJECTIVE: Monocyte proinflammatory activity has been demonstrated in obesity, insulin resistance, and type 2 diabetes, metabolic conditions that are frequently associated with elevated levels of nonesterified fatty acids (NEFA). We therefore tested the hypothesis that NEFA may induce monocyte inflammation. METHODS AND RESULTS: Monocytes exposed to NEFA for 2 days demonstrated a dose-related increase in intracellular reactive oxygen species (ROS) formation and adhesion to endothelial cells. All of these effects were inhibited by the coaddition of antioxidants such as glutathione or butylated hydroxytoluene, by inhibition of ROS generation by NADPH oxidase inhibitors, and by inhibition of protein kinase C, a recognized stimulator of NAPDH oxidase. Monocytes exposed to NEFA also demonstrated a significant increase in CD11b message expression. Stimulation of monocyte adhesion to endothelial cells by NEFA was inhibited by addition of neutralizing antibodies to either CD11b or CD18. Finally, surface expression of CD11b increased significantly on monocytes as measured by flow cytometry, after their incubation with NEFA. CONCLUSIONS: These studies indicate that elevated concentrations of NEFA may enhance integrin facilitated monocyte adhesion to endothelial cells and these effects appear mediated, in part, through activation of NADPH oxidase and oxidative stress.

HDL inhibits saturated fatty acid mediated augmentation of innate immune responses in endothelial cells by a novel pathway.

BACKGROUND AND AIMS: Peripheral insulin resistance is associated with several metabolic abnormalities, including elevated serum fatty acids that contribute to vascular injury and atherogenesis. Our goals were to examine whether saturated fatty acids can modify innate immune responses to subclinical concentrations of lipopolysaccharide (LPS) in endothelial cells, and to explore the underlying pathway and determine whether it is modified by high density lipoprotein (HDL) and other factors commonly altered in insulin resistance. METHODS: Physiologic concentrations of palmitic acid were added to human aortic endothelial cells with and without a variety of inhibitors or HDL and measures of cell inflammation and function assessed. RESULTS: Palmitic acid significantly amplified human aortic endothelial cell inflammatory responses to LPS. Similar results were obtained from lipolysis products of triglyceride rich lipoproteins. Metabolism of palmitic acid to ceramide and subsequent activation of PKC-ζ, MAPK and ATF3 appeared critical in amplifying LPS induced inflammation. The amplified response to palmitic acid/LPS was decreased by HDL, dose dependently, and this inhibition was dependent on activation of PI3K/AKT and reduction in ATF3. CONCLUSIONS: These results indicate that endothelial cell innate immune responses are modified by metabolic abnormalities commonly present in insulin resistance and provide evidence for a novel mechanism by which HDL may reduce vascular inflammation.

Transcriptional analyses of natural leaf senescence in maize.

Leaf senescence is an important biological process that contributes to grain yield in crops. To study the molecular mechanisms underlying natural leaf senescence, we harvested three different developmental ear leaves of maize, mature leaves (ML), early senescent leaves (ESL), and later senescent leaves (LSL), and analyzed transcriptional changes using RNA-sequencing. Three sets of data, ESL vs. ML, LSL vs. ML, and LSL vs. ESL, were compared, respectively. In total, 4,552 genes were identified as differentially expressed. Functional classification placed these genes into 18 categories including protein metabolism, transporters, and signal transduction. At the early stage of leaf senescence, genes involved in aromatic amino acids (AAAs) biosynthetic process and transport, cellular polysaccharide biosynthetic process, and the cell wall macromolecule catabolic process, were up-regulated. Whereas, genes involved in amino acid metabolism, transport, apoptosis, and response to stimulus were up-regulated at the late stage of leaf senescence. Further analyses reveals that the transport-related genes at the early stage of leaf senescence potentially take part in enzyme and amino acid transport and the genes upregulated at the late stage are involved in sugar transport, indicating nutrient recycling mainly takes place at the late stage of leaf senescence. Comparison between the data of natural leaf senescence in this study and previously reported data for Arabidopsis implies that the mechanisms of leaf senescence in maize are basically similar to those in Arabidopsis. A comparison of natural and induced leaf senescence in maize was performed. Athough many basic biological processes involved in senescence occur in both types of leaf senescence, 78.07% of differentially expressed genes in natural leaf senescence were not identifiable in induced leaf senescence, suggesting that differences in gene regulatory network may exist between these two leaf senescence programs. Thus, this study provides important information for understanding the mechanism of leaf senescence in maize.