The prevention of fungal proliferation in postharvest grains is critical for maintaining grain quality and reducing mycotoxin contamination. Fumigation with natural gaseous fungicides is a promising ...and sustainable approach to protect grains from fungal spoilage. In this study, the antifungal activities of (
E
)-2-alkenals (C
5
-C
10
) on
Aspergillus flavus
were tested in the vapor phase, and (
E
)-2-heptenal showed the highest antifungal activity against
A. flavus
. (
E
)-2-Heptenal completely inhibited
A. flavus
growth at 0.0125 µL/mL and 0.2 µL/mL in the vapor phase and liquid contact, respectively. (
E
)-2-Heptenal can disrupt the plasma membrane integrity of
A. flavus
via leakage of intracellular electrolytes. Scanning electron microscopy indicated that the mycelial morphology of
A. flavus
was remarkably affected by (
E
)-2-heptenal. Metabolomic analyses indicated that 49 metabolites were significantly differentially expressed in
A. flavus
mycelia exposed to 0.2 µL/mL (
E
)-2-heptenal; these metabolites were mainly involved in galactose metabolism, starch and sucrose metabolism, the phosphotransferase system, and ATP-binding cassette transporters. ATP production was reduced in (
E
)-2-heptenal-treated
A. flavus
, and Janus Green B staining showed reduced cytochrome
c
oxidase activity. (
E
)-2-Heptenal treatment induced oxidative stress in
A. flavus
mycelia with an accumulation of superoxide anions and hydrogen peroxide and increased activities of superoxide dismutase and catalase. Simulated storage experiments showed that fumigation with 400 µL/L of (
E
)-2-heptenal vapor could completely inhibit
A. flavus
growth in wheat grains with 20% moisture; this demonstrates its potential use in preventing grain spoilage. This study provides valuable insights into understanding the antifungal effects of (
E
)-2-heptenal on
A. flavus
.
Key points
•
(E)-2-Heptenal vapor showed the highest antifungal activity against A. flavus among (C
5
-C
10
) (E)-2-alkenals
.
•
The antifungal effects of (E)-2-heptenal against A. flavus were determined
.
•
The antifungal actions of (E)-2-heptenal on A. flavus were revealed by metabolomics and biochemical analyses
.
Monodisperse poly(acrylic acid)‐modified Fe3O4 (PAA@Fe3O4) hybrid microspheres with dual responses (magnetic field and pH) were successfully fabricated. The PAA polymer was encapsulated into the ...inner cavity of Fe3O4 hollow spheres by a vacuum‐casting route and photo‐initiated polymerization. TEM images show that the samples consist of monodisperse porous spheres with a diameter around 200 nm. The Fe3O4 spheres, after modification with the PAA polymer, still possess enough space to hold guest molecules. We selected doxorubicin (DOX) as a model drug to investigate the drug loading and release behavior of as‐prepared composites. The release of DOX molecules was strongly dependent on the pH value due to the unique property of PAA. The HeLa cell‐uptake process of DOX‐loaded PAA@Fe3O4 was observed by confocal laser scanning microscopy (CLSM). After being incubated with HeLa cells under magnet magnetically guided conditions, the cytotoxtic effects of DOX‐loaded PAA@Fe3O4 increased. These results indicate that pH‐responsive magnetic PAA@Fe3O4 spheres have the potential to be used as anticancer drug carriers.
Dual response: Monodisperse poly(acrylic acid)‐modified Fe3O4 (PAA@Fe3O4) hybrid microspheres with dual responses (magnetic field and pH) were successfully fabricated (see figure). The drug release behavior was strongly dependent on pH value due to the unique properties of PAA. Furthermore, doxorubicin (DOX)‐loaded PAA@Fe3O4 composites show an enhanced magnetically guided anticancer effect.
The “curse of dimensionality” is a major problem in dynamic programming (DP) algorithms for large-scale hydropower systems. This study proposes a parallel DP algorithm based on Spark (PDPoS) to ...alleviate the “curse of dimensionality”. Parallel computing experiments are formulated by varying the number of reservoirs, the number of discrete water levels and the number of CPU cores to analyze the quality and efficiency of PDPoS. The methodologies were applied to a cascade reservoir system made up of eight reservoirs in the Yuanshui River Basin in China. The results are as follows. (1) The number of discrete water levels is the dominant factor in the solution quality, while the number of reservoirs is the dominant factor in the solving efficiency. (2) The runtime of PDPoS is markedly affected by the calculational scale (determined by the number of reservoirs and discrete water levels), and the relationship between the number of CPU cores and the runtime is triphasic with increasing calculational scale. (3) The larger the calculational scale is, the better the parallel performance (i.e., the parallel speedup and parallel efficiency). The proposed PDPoS method has strong generality, high parallel performance, and high practical value.
As an essential part of the hydrological cycle, precipitation directly contributes to surface runoff and river runoff formation. Simulation on precipitation variables can effectively solve the ...adverse effects on hydrological assessment in some areas with insufficient or even no runoff observation. With the widespread use of various weather generators, the traditional stochastic hydrological simulation methods tend to be gradually replaced. To compare these two approaches mentioned above, this paper utilizes the precipitation records from 1958 to 2011 at nine meteorological stations within Huaihe River System in Henan Province to evaluate a stochastic hydrological simulation method, SARIMA model, and two types of weather generators, WeaGETS and LARS-WG, through the comparison of statistical characteristics regarding precipitation variables, such as mean, mean square error, extreme value and coefficient of variation. The results show that (1) on the annual scale, SARIMA has a better performance to reproduce the mean and mean square error as well as the extreme precipitation events than weather generators; (2) regarding the monthly-scale precipitation simulation, SARIMA is good at reproducing the statistical properties of monthly precipitation at the average level, while WeaGETS and LARS-WG work better in simulating monthly precipitation extremes; (3) compared with weather generators, SARIMA is highly constrained by the observed records, and among these two weather generators, WeaGETS scores higher on monthly precipitation simulation under the same sample length conditions. In conclusion, the traditional hydrological simulation method, SARIMA, and weather generators, WeaGETS and LARS-WG, have both benefits and drawbacks. The appropriate choice depends on different research backgrounds and purposes.
Plant volatile organic compounds (PVOCs) have gained increasing attention for their role in preventing fungal spoilage and insect contamination in postharvest agro-products owing to their ...effectiveness and sustainability. In this study, the essential oil was extracted from fresh M. alternifolia (tea tree) leaves, and the fumigation vapor of tea tree oil (TTO) completely inhibited the growth of Aspergillus flavus on agar plates at a concentration of 1.714 μL/mL. Terpinen-4-ol was identified as the major component (40.76 %) of TTO volatiles analyzed using headspace gas chromatography–mass spectrometry. Terpinen-4-ol vapor completely inhibited the A. flavus growth on agar plates and 20 % moisture wheat grain at 0.556 and 1.579 μL/mL, respectively, indicating that terpinen-4-ol serves as the main antifungal constituent in TTO volatiles. The minimum inhibitory concentration of terpinen-4-ol in liquid-contact culture was 1.6 μL/mL. Terpinen-4-ol treatment caused depressed, wrinkled, and punctured mycelial morphology and destroyed the plasma membrane integrity of A. flavus. Metabolomics analysis identified significant alterations in 93 metabolites, with 79 upregulated and 14 downregulated in A. flavus mycelia exposed to 1.6 μL/mL terpinen-4-ol for 6 h, involved in multiple cellular processes including cell membrane permeability and integrity, the ABC transport system, pentose phosphate pathway, and the tricarboxylic acid cycle. Biochemical analysis and 2,7-dichlorofluorescein diacetate staining showed that terpinen-4-ol induced oxidative stress and mitochondrial dysfunction in A. flavus mycelia. This study provides new insights into the antifungal effects of the main TTO volatile compounds terpinen-4-ol on the growth of A. flavus.
•Terpinen-4-ol is the main volatile component of TTO determined by HS-GC–MS.•Terpinen-4-ol effectively inhibited the growth of A. flavus in high-moisture wheat grains.•Terpinen-4-ol inhibited the growth of A. flavus in both vapor phase and liquid contact.•The inhibitory mechanism of terpinen-4-ol on A. flavus was revealed by metabonomics analysis.
Structural and functional analysis of genome-based large-scale metabolic networks is important for understanding the design principles and regulation of the metabolism at a system level. The ...metabolic network is conventionally considered to be highly integrated and very complex. A rational reduction of the metabolic network to its core structure and a deeper understanding of its functional modules are important.
In this work, we show that the metabolites in a metabolic network are far from fully connected. A connectivity structure consisting of four major subsets of metabolites and reactions, i.e. a fully connected sub-network, a substrate subset, a product subset and an isolated subset is found to exist in metabolic networks of 65 fully sequenced organisms. The largest fully connected part of a metabolic network, called 'the giant strong component (GSC)', represents the most complicated part and the core of the network and has the feature of scale-free networks. The average path length of the whole network is primarily determined by that of the GSC. For most of the organisms, GSC normally contains less than one-third of the nodes of the network. This connectivity structure is very similar to the 'bow-tie' structure of World Wide Web. Our results indicate that the bow-tie structure may be common for large-scale directed networks. More importantly, the uncovered structure feature makes a structural and functional analysis of large-scale metabolic network more amenable. As shown in this work, comparing the closeness centrality of the nodes in the GSC can identify the most central metabolites of a metabolic network. To quantitatively characterize the overall connection structure of the GSC we introduced the term 'overall closeness centralization index (OCCI)'. OCCI correlates well with the average path length of the GSC and is a useful parameter for a system-level comparison of metabolic networks of different organisms.
http://genome.gbf.de/bioinformatics/
Plant volatile compounds have great potential for preventing and controlling fungal spoilage in post-harvest grains. Recently, we have reported the antifungal effects of
trans
-anethole, the main ...volatile constituent of the
Illicium verum
fruit, on
Aspergillus flavus
. In this study, the inhibitory mechanisms of
trans
-anethole against the growth of
A. flavus
mycelia were investigated using transcriptomic and biochemical analyses. Biochemical and transcriptomic changes in
A. flavus
mycelia were evaluated after exposure to 0.2 μL/mL
trans
-anethole. Scanning electron microscopy showed that
trans
-anethole treatment resulted in the surface wrinkling of
A. flavus
mycelia, and calcofluor white staining confirmed that
trans
-anethole treatment disrupted the mycelial cell wall structure. Annexin V-fluorescein isothiocyanate/propidium iodide double staining suggested that
trans
-anethole induced apoptosis in
A. flavus
mycelia. Reduced mitochondrial membrane potential and DNA damage were observed in
trans
-anethole-treated
A. flavus
mycelia using 5,5′,6,6′-tetrachloro-1,1′,3,3′-tetraethyl-imidacarbocyanine and 4′,6-diamidino-2-phenylindole staining, respectively. 2′,7′- Dichloro-dihydro-fluorescein diacetate staining and biochemical assays demonstrated that
trans
-anethole treatment cause the accumulation of reactive oxygen species in the
A. flavus
mycelia. Transcriptome results showed that 1673 genes were differentially expressed in
A. flavus
mycelia exposed to
trans
-anethole, which were mainly associated with multidrug transport, oxidative phosphorylation, citric acid cycle, ribosomes, and cyclic adenosine monophosphate signaling. We propose that
trans
-anethole can inhibit the growth of
A. flavus
mycelia by disrupting the cell wall structure, blocking the multidrug transport process, disturbing the citric acid cycle, and inducing apoptosis. This study provides new insights into the inhibitory mechanism of
trans
-anethole on
A. flavus
mycelia and will be helpful for the development of natural fungicides.
Key points
•
Biochemical analyses of A. flavus mycelia exposed to trans-anethole were performed
•
Transcriptomic changes in trans-anethole-treated A. flavus mycelia were analyzed
•
An inhibitory mechanism of trans-anethole on the growth of A. flavus mycelia was proposed
The joint optimal operation of cascade reservoir system can greatly improve the utilization of water resources. However, the complex high-dimensional and non-linear features and calculated costs ...often hinder the refined operation and management of reservoirs. Recently, the local parallel computing has become an effective way to alleviate the "curse of dimensionality". Current local parallel computing has hardware limitations, which is difficult to adapt to large-scale computing. This study proposes a novel parallel dynamic programming algorithm based on Spark (PDPoS) via cloud computing. The simulation experiments are carried out for a comparative analysis of the solution efficiency, influence factors and stability of cloud computing. The results are as follows: (1) The efficiency of the cloud-based PDPoS is related to some factors; the number of CPU cores is the main influencing factor, followed by the operator, and the architecture has the least influence. (2) The runtime variance of cloud computing is 2.03, indicating cloud computing has high stability. (3) Under the same configuration (i.e., CPU and memory), the runtime of cloud computing is 41.5% ~ 110.3% longer than that of physical machines. However, cloud computing has rich resources, good scalability, and good portability of online operations, which is an attractive alternative for optimal operation of large-scale reservoir system.
Cellular functions are coordinately carried out by groups of genes forming functional modules. Identifying such modules in the transcriptional regulatory network (TRN) of organisms is important for ...understanding the structure and function of these fundamental cellular networks and essential for the emerging modular biology. So far, the global connectivity structure of TRN has not been well studied and consequently not applied for the identification of functional modules. Moreover, network motifs such as feed forward loop are recently proposed to be basic building blocks of TRN. However, their relationship to functional modules is not clear.
In this work we proposed a top-down approach to identify modules in the TRN of E. coli. By studying the global connectivity structure of the regulatory network, we first revealed a five-layer hierarchical structure in which all the regulatory relationships are downward. Based on this regulatory hierarchy, we developed a new method to decompose the regulatory network into functional modules and to identify global regulators governing multiple modules. As a result, 10 global regulators and 39 modules were identified and shown to have well defined functions. We then investigated the distribution and composition of the two basic network motifs (feed forward loop and bi-fan motif) in the hierarchical structure of TRN. We found that most of these network motifs include global regulators, indicating that these motifs are not basic building blocks of modules since modules should not contain global regulators.
The transcriptional regulatory network of E. coli possesses a multi-layer hierarchical modular structure without feedback regulation at transcription level. This hierarchical structure builds the basis for a new and simple decomposition method which is suitable for the identification of functional modules and global regulators in the transcriptional regulatory network of E. coli. Analysis of the distribution of feed forward loops and bi-fan motifs in the hierarchical structure suggests that these network motifs are not elementary building blocks of functional modules in the transcriptional regulatory network of E. coli.
Given the institutional limitations of multi-stakeholders, exploring the synergistic revenue from the joint reservoir operations of a multi-stakeholder multi-reservoir system requires a synergistic ...revenue allocation mechanism to ensure a beneficial solution for multi stakeholders. This study established a synergistic revenue allocation model using bargaining game theory under the principles of equity, rationality, and efficiency. For the maximization the Nash product of gains in the utility of stakeholders and constraints on the feasibility of allocation plans considering all the possible formations of sub-coalitions, the analytic optimal solution of the bargaining model was derived using the first-order optimality condition. The optimal revenue allocation plan meets the conditions of the equal quasi-marginal utility function among stakeholders. The methodologies were applied to a hypothetical cascade reservoir system operated by multiple stakeholders. Compared with the revenue allocation plans obtained by a proportional rule method and the Shapley value method, the results corroborate that (1) the allocation plan of the bargaining model is jointly determined by the interval of the revenue range of each reservoir and the effectiveness of the sub-coalition constraints, indicating that the allocated synergistic revenue is positively correlated with the singleton contribution and team contribution on the total revenue of the grand coalition; (2) the difference in the plans obtained by the three methods is generally determined by the difference in equity definition; and (3) the synergistic revenue allocation plan obtained from the bargaining model is the highest homogenized among all reservoirs (stakeholders), which demonstrates that the revenue of those dominated stakeholders can be improved compared with other plans. The proposed methodologies provide new insights to guide benefit share decisions in multi-stakeholder reservoirs system.
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