In this paper, the stabilization of a class of hybrid stochastic systems whose drift coefficients satisfy high nonlinear growth conditions is studied. A periodically intermittent controller based on discrete time state observations is designed. The core idea of this paper is to derive the stability of the controlled system by constructing Lyapunov function. An example is given to prove the validity of the conclusion.

In this work, we consider a class of switched stochastic reaction-diffusion systems (SSRDSs, in short), where the discrete switching signal is a right continuous, piecewise function and the switching instants are stopping times or deterministic times. Criteria on finite-time stability in the probability of the trivial solution for SSRDSs are derived by means of Lyapunov functional methods. We propose an example to verify the obtained theoretical results.

The main purpose of this paper is to investigate the practical stability in relation to a part of the variables of stochastic reaction–diffusion systems driven by G-Brownian motion (G-SRDSs, in short). With the aid of G-Lyapunov techniques and G-Itô's formula, the criteria of the global practical uniform kth moment exponential stability and the global practical uniform quasi surely exponential stability in relation to a part of variables of G-SRDSs are established. An example is given to illustrate the usefulness and feasibility of the proposed results.

生物化学是高校食品类专业重要的专业基础课程.本文从课程讲授、教学互动、开放式作业和教学评价等方面探讨了我校一流本科专业建设中食品类专业生物化学课程教学改革与实践.

As a signaling molecule, hydrogen sulfide (H2S) plays an indispensable role in the modulation of ripening and senescence in fruits and vegetables. To explore the role of H2S in regulating metabolism of postharvest tomato, ripening-related physiological parameters, activities of antioxidant enzymes and gene expression were analyzed in H2S-fumigated tomato fruits. These results show that H2S significantly delayed the color transition and softening of tomato fruit, and maintained higher level of flavonoids and lower level of anthocyanin during storage. Besides, H2S could maintain higher level of nutritional-related metabolites, such as reducing sugar, ascorbic acid during postharvest storage. Moreover, H2S decreased the rate of O2− production, inhibited the production of H2O2 and malondialdehyde (MDA), enhanced the activities of antioxidant enzymes including ascorbate peroxidase (APX), superoxide dismutase (SOD), catalase (CAT) and guaiacol peroxidase (POD) in tomato fruits, while reduced the activities of phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO) and lipoxygenase (LOX). Besides, the expression of the antioxidant-encoding genes SlCAT2, SlPOD12 was generally upregulated with H2S fumigation. Principal component analysis (PCA) suggests that H2S induced significant discrepancy mainly to the differences in firmness, anthocyanin, flavonoid and the activity of guaiacol peroxidase (POD), and the correlation analysis further shows that H2S affected pigment metabolism and nutritional quality. In conclusion, H2S could maintain better appearance and nutritional quality, and prolong the storage period of postharvest tomato fruits through activating the antioxidative system.

This paper studies the asymptotic behavior of the mild solution for a class of perturbed impulsive neutral stochastic functional differential equations driven by fractional Brownian motion in Hilbert space. We establish the conditions under which the mild solutions of perturbed impulsive neutral stochastic functional differential equation and the unperturbed one are close on finite time interval when the perturbation tends to zero. Moreover, we show the result holds on time interval whose length tends to infinity as the perturbation tends to zero. As an application, the asymptotic behavior of the mild solution for a class of perturbed impulsive neutral stochastic partial differential equations driven by fractional Brownian motion in Hilbert space is proposed to show the feasibility of the obtained result.

Background Anthocyanins, which have important biological functions and have a beneficial effect on human health, notably account for pigmentation in purple-fleshed sweet potato tuberous roots. Individual regulatory factors of anthocyanin biosynthesis have been identified; however, the regulatory network of anthocyanin biosynthesis in purple-fleshed sweet potato is unclear. Results We functionally determined that IbMYB340 cotransformed with IbbHLH2 in tobacco and strawberry receptacles induced anthocyanin accumulation, and the addition of IbNAC56a or IbNAC56b caused increased pigmentation. Furthermore, we confirmed the interaction of IbMYB340 with IbbHLH2 and IbNAC56a or IbNAC56b via yeast two-hybrid and firefly luciferase complementation assays; these proteins could form a MYB340-bHLH2-NAC56a or MYB340-bHLH2-NAC56b transcriptional complex to regulate anthocyanin biosynthesis by binding to the IbANS promoter rather than the IbUFGT promoter. Furthermore, it was found by a transient expression system in tobacco leaves that IbMYB44 could decrease anthocyanin accumulation. Moreover, the interaction of IbMYB44 with IbMYB340 and IbNAC56a or IbNAC56b was verified. This result suggested that IbMYB44 acts as a repressor of anthocyanin in sweet potato. Conclusions The repressor IbMYB44 affected anthocyanin biosynthesis by competitively inhibiting the IbMYB340-IbbHLH2-IbNAC56a or IbMYB340-IbbHLH2-IbNAC56b regulatory complex formation. Overall, the present study proposed a novel regulatory network whereby several vital TFs play key roles in regulating anthocyanin biosynthesis, and it provides strong insight into the potential mechanism underlying anthocyanin biosynthesis in sweet potato tuberous roots with purple color.

Red pear is favored because of its bright appearance and abundant anthocyanins. Anthocyanin biosynthesis is controlled by transcription factors (TFs) forming regulatory complexes. In red-skinned pears, the WRKY TFs have a significant relationship with anthocyanin biosynthesis, but the molecular mechanism of the WRKY TFs involved in regulating color formation in red-skinned pear is unclear. In this study, the TFs PyWRKY31 and PyWRKY26 were screened as candidate genes for controlling anthocyanin biosynthesis by transcriptome data and bioinformatics analysis. The effect of anthocyanin accumulations after cotransformation of PyWRKY31 or PyWRKY26 with its partners PyMYB10, PyMYB114, and PybHLH3 was verified in tobacco leaves and strawberry receptacles by a transient expression system. RT-qPCR analysis and a dual-luciferase reporter system further confirmed that this cotransformation activated the expression of PyDFR, PyANS, and PyUFGT in anthocyanin biosynthesis and PyGST in anthocyanin transport instead of the PyABC transporter and PyAVP. Furthermore, the cotransformed PyWRKY26 and PybHLH3 could bind to the PyMYB114 promoter, and PyWRKY26 directly activated the transcription of PyMYB114. In addition, the TF PyWRKY26 could interact with PybHLH3, as confirmed by firefly luciferase complementation and yeast two-hybrid (Y2H) assays. These results showed that the interaction of PyWRKY26 and PybHLH3 could cotarget the PyMYB114 promoter, which resulted in anthocyanin accumulation in red-skinned pear. This study further strengthened the understanding of the regulatory mechanism of anthocyanin accumulation and contributed to improving the appearance of red-skinned pears.

Anthocyanins, which have important biological functions and have a beneficial effect on human health, notably account for pigmentation in purple-fleshed sweet potato tuberous roots. Individual regulatory factors of anthocyanin biosynthesis have been identified; however, the regulatory network of anthocyanin biosynthesis in purple-fleshed sweet potato is unclear. We functionally determined that IbMYB340 cotransformed with IbbHLH2 in tobacco and strawberry receptacles induced anthocyanin accumulation, and the addition of IbNAC56a or IbNAC56b caused increased pigmentation. Furthermore, we confirmed the interaction of IbMYB340 with IbbHLH2 and IbNAC56a or IbNAC56b via yeast two-hybrid and firefly luciferase complementation assays; these proteins could form a MYB340-bHLH2-NAC56a or MYB340-bHLH2-NAC56b transcriptional complex to regulate anthocyanin biosynthesis by binding to the IbANS promoter rather than the IbUFGT promoter. Furthermore, it was found by a transient expression system in tobacco leaves that IbMYB44 could decrease anthocyanin accumulation. Moreover, the interaction of IbMYB44 with IbMYB340 and IbNAC56a or IbNAC56b was verified. This result suggested that IbMYB44 acts as a repressor of anthocyanin in sweet potato. The repressor IbMYB44 affected anthocyanin biosynthesis by competitively inhibiting the IbMYB340-IbbHLH2-IbNAC56a or IbMYB340-IbbHLH2-IbNAC56b regulatory complex formation. Overall, the present study proposed a novel regulatory network whereby several vital TFs play key roles in regulating anthocyanin biosynthesis, and it provides strong insight into the potential mechanism underlying anthocyanin biosynthesis in sweet potato tuberous roots with purple color.

Hydrogen sulfide (H2S) could act as a versatile signaling molecule in delaying fruit ripening and senescence. Ethylene (C2H4) also plays a key role in climacteric fruit ripening, but little attention has been given to its interaction with H2S in modulating fruit ripening and senescence. To study the role of H2S treatment on the fruit quality and nutrient metabolism, tomato fruits at white mature stage were treated with ethylene and ethylene plus H2S. By comparing to C2H4 treatment, we found that additional H2S significantly delayed the color change of tomato fruit, and maintained higher chlorophyll and lower flavonoids during storage. Moreover, H2S could inhibit the activity of protease, maintained higher levels of nutritional-related metabolites, such as anthocyanin, starch, soluble protein, ascorbic acid by comparing to C2H4 treatment. Gene expression analysis showed that additional H2S attenuated the expression of beta-amylase encoding gene BAM3, UDP-glycosyltransferase encoding genes, ethylene-responsive transcription factor ERF003 and DOF22. Furthermore, principal component analysis suggested that starch, titratable acids, and ascorbic acid were important factors for affecting the tomato storage quality, and the correlation analysis further showed that H2S affected pigments metabolism and the transformation of macromolecular to small molecular metabolites. These results showed that additional H2S could maintain the better appearance and nutritional quality than C2H4 treatment alone, and prolong the storage period of post-harvest tomato fruits.

Hydrogen sulfide (H 2 S) is a gaseous signaling molecule that plays multiple roles in plant development. However, whether endogenous H 2 S plays a role in fruit ripening in tomato is still unknown. In this study, we show that the H 2 S-producing enzyme l -cysteine desulfhydrase SlLCD1 localizes to the nucleus. By constructing mutated forms of SlLCD1, we show that the amino acid residue K24 of SlLCD1 is the key amino acid that determines nuclear localization. Silencing of SlLCD1 by TRV-SlLCD1 accelerated fruit ripening and reduced H 2 S production compared with the control. A SlLCD1 gene-edited mutant obtained through CRISPR/Cas9 modification displayed a slightly dwarfed phenotype and accelerated fruit ripening. This mutant also showed increased cysteine content and produced less H 2 S, suggesting a role of SlLCD1 in H 2 S generation. Chlorophyll degradation and carotenoid accumulation were enhanced in the SlLCD1 mutant. Other ripening-related genes that play roles in chlorophyll degradation, carotenoid biosynthesis, cell wall degradation, ethylene biosynthesis, and the ethylene signaling pathway were enhanced at the transcriptional level in the lcd1 mutant. Total RNA was sequenced from unripe tomato fruit treated with exogenous H 2 S, and transcriptome analysis showed that ripening-related gene expression was suppressed. Based on the results for a SlLCD1 gene-edited mutant and exogenous H 2 S application, we propose that the nuclear-localized cysteine desulfhydrase SlLCD1 is required for endogenous H 2 S generation and participates in the regulation of tomato fruit ripening.

As one of the important hybrid models, stochastic fluid models (SFMs, in short) have many applications. In this work, we discuss a class of SFMs modulated by Markovian chain with lower and upper jumps, where the fluid level has a positive upper bound and a lower bound zero. The joint limiting distribution of the buffer level and the environment state is expressed by a series of differential equations. An example is give to illustrate the theory obtained.

In this paper, we introduce a class of Sobolev-type stochastic differential equations driven by G-Brownian motion (G-SSDEs, in short). We prove the existence and uniqueness of the mild solution for G-SSDEs. By means of two integral inequalities, the attracting and quasi-invariant sets of the equations are obtained. As a byproduct, the exponentially stability of the solution in mean-square sense is derived. An example is given to illustrate the obtained theoretical results.

Hydrogen sulfide (H 2 S) has been proven to be a multifunctional signaling molecule in plants. In this study, we attempted to explore the effects of H 2 S on the climacteric fruit tomato during postharvest storage. H 2 S fumigation for 1 d was found to delay the peel color transition from green to red and decreased fruit firmness induced by ethylene. Further investigation showed that H 2 S fumigation downregulated the activities and gene expressions of cell wall–degrading enzymes pectin lyase (PL), polygalacturonase (PG), and cellulase. Furthermore, H 2 S fumigation downregulated the expression of ethylene biosynthesis genes SlACS2 and SlACS3. Ethylene treatment for 1 d was found to induce the expression of SlACO1, SlACO3 , and SlACO4 genes, whereas the increase was significantly inhibited by H 2 S combined with ethylene. Furthermore, H 2 S decreased the transcript accumulation of ethylene receptor genes SlETR5 and SlETR6 and ethylene transcription factors SlCRF2 and SlERF2 . The correlation analysis suggested that the fruit firmness was negatively correlated with ethylene biosynthesis and signaling pathway. The current study showed that exogenous H 2 S could inhibit the synthesis of endogenous ethylene and regulate ethylene signal transduction, thereby delaying fruit softening and the ripening process of tomato fruit during postharvest storage.

The activities and gene expression of antioxidative enzymes and the ROS content were analyzed in two typical storage-tolerant cultivars (Xushu 32 and Shangshu 19) and another two storage-sensitive cultivars (Yanshu 25 and Sushu 16) to explore the association between the storage capacity of sweetpotato (Ipomoea batatas (L.) Lam) and ROS scavenging capability. The storage roots of the storage-tolerant cultivars maintained higher activities and expression levels of antioxidative enzymes, including ascorbate peroxidase (APX), peroxidase (POD), catalase (CAT), and superoxide dismutase (SOD); lower activity and expression of lipoxygenase (LOX); and lower accumulation of ROS metabolites compared with the storage-sensitive cultivars. The antioxidative capability and ROS parameters of leaves were positively correlated with those of storage roots. Our results provide valuable insight for evaluating the storability of sweetpotato cultivars by analyzing the capabilities of the antioxidative system and the contents of ROS metabolites.

This paper investigates the problem of stochastic Cohen–Grossberg neural networks driven by G-Brownian motion (G-SCGNNs, in short). We establish the exponential synchronization of G-SCGNNs by applying inequality technique, kth vertex-G-Lyapunov functions, graph-theory and state feedback control technique. A concrete example is given to verify the obtained theory.

In this work, we discuss a kind of pantograph stochastic functional differential equations driven by G-Brownian motion (G-PSDEs, in short). When the coefficients satisfy local Lipschitz and generalized Lyapunov conditions, we establish existence, uniqueness, asymptotic boundedness and exponential stability of the solution for G-PSDEs.

BACKGROUND:Sweet potato is susceptible to chilling injury during low-temperature storage. To explore the correlation between chilling injury and reactive oxygen species (ROS) metabolism, the content of ROS and the activities and gene expression of antioxidant enzymes were analyzed in the typical storage-tolerant cultivar Xushu 32 and storage-sensitive cultivar Yanshu 25.RESULTS:The activities of antioxidant enzymes including ascorbate peroxidase (APX), superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GR) were enhanced rapidly in the early period of storage in response to chilling stress. Thereafter, the content of ROS metabolites increased consistently due to gradual decrease in ROS scavenging enzymes. Storage-tolerant cultivar Xushu 32 had higher antioxidant enzyme activities and gene expressions as well as higher content of antioxidant metabolites and lower content of ROS metabolites compared with storage-sensitive cultivar Yanshu 25, suggesting that the capacity of ROS scavenging by antioxidant enzymes and antioxidants is highly associated with the tolerance of sweet potato to chilling stress.CONCLUSION:These results indicated that the antioxidative system is activated in the storage root of sweet potato and the antioxidative capacity is positively associated with better storage performance in the storage-tolerant cultivar. © 2019 Society of Chemical Industry.

Aspergillus niger, which is a fungal pathogen, causes rot in a variety of fruits. In this study, the cystathionine β-synthase cbsA gene was deleted by homologous recombination to study its role in sulfur metabolism and pathogenicity of A. niger. The results showed that Δ cbsA strain maintained normal mycelia growth and sporulation compared with the control strain A. niger MA 70.15, whereas the contents of cysteine and glutathione (GSH) increased significantly after cbsA deletion. However, Δ cbsA strain showed reduced endogenous H2S production. Further results showed that cbsA gene deletion induced higher resistance to cadmium stress and stronger infectivity to pears. It was also found that a stronger response of reactive oxygen species (ROS) production was induced in Δ cbsA mutant-infected pear compared with the control strain. In all, the present research suggested the important role of cbsA in sulfur metabolism and pathogenicity of A. niger in pear fruit.