Background AFB_(1)-8,9-exo-epoxide(AFBO)is the highly toxic product of Aflatoxin B_(1)(AFB_(1)).Glutathione S-transferases(GSTs)play pivotal roles in detoxifying AFB_(1) by catalyzing the conjugation of AFBO with glut...Background AFB_(1)-8,9-exo-epoxide(AFBO)is the highly toxic product of Aflatoxin B_(1)(AFB_(1)).Glutathione S-transferases(GSTs)play pivotal roles in detoxifying AFB_(1) by catalyzing the conjugation of AFBO with glutathione(GSH).Although there are over 20 GST isozymes that have been identified in chicken,GST isozymes involved in the detoxification process of AFB_(1) have not been identified yet.The objective of this study was to determine which GST isozymes played key role in detoxification of AFB_(1).Results A total of 17 pcDNA3.1(+)-GST isozyme plasmids were constructed and the GST isozyme genes were overexpressed by 80–2,500,000 folds in the chicken Leghorn male hepatoma(LMH)cells.Compared to the AFB_(1) treatment,overexpression of GSTA2X,GSTA3,GSTT1L,GSTZ1-1,and GSTZ1-2 increased the cell viability by 6.5%–17.0%in LMH cells.Moreover,overexpression of five GST isozymes reduced the release of lactate dehydrogenase and reactive oxygen species by 8.8%–64.4%,and 57.2%–77.6%,respectively,as well as enhanced the production AFBO-GSH by 15.8%–19.6%,thus mitigating DNA damage induced by AFB_(1).After comprehensive evaluation of various indicators,GSTA2X displayed the best detoxification effects against AFB_(1).GSTA2X was expressed in Pichia pastoris X-33 and its enzymatic properties for catalyzing the conjugation of AFBO with GSH showed that the optimum temperature and pH were 20–25℃ and 7.6–8.6 as well as the enzymatic kinetic parameter V_(max) was 0.23 nmol/min/mg and the Michaelis constant was 86.05μmol/L with the AFB_(1) as substrate.Conclusions In conclusion,GSTA2X,GSTA3,GSTT1L,GSTZ1-1,and GSTZ1-2 played key roles in AFB_(1) detoxification,which will provide new remediation strategies to prevent aflatoxicosis in chickens.展开更多
Aiming to provide a theoretical basis for possible uses of flaxseed as a food supplement and functional ingredient, the heat treatment of flaxseed was carried out using steaming, roasting, and microwave methods to inv...Aiming to provide a theoretical basis for possible uses of flaxseed as a food supplement and functional ingredient, the heat treatment of flaxseed was carried out using steaming, roasting, and microwave methods to investigate the detoxification effects of these three pretreatment methods on flaxseed, as well as the impact of the three methods on the quality of flaxseed. The results showed that all three pretreatment methods had better detoxification effects on flaxseed, in which, microwave treatment was the most effective method. After 5 min of microwave treatment, the hydrogen cyanide(HCN) content in flaxseed decreased from(94.65±1.68) mg/kg to(7.80±0.57) mg/kg. All three pretreatment methods significantly reduced the water content in flaxseed but had a weaker effect on protein, fat, and ash contents. After pretreatment by the three methods, the polyphenol content, peroxide value(POV), and a*value of flaxseed increased significantly, thiobarbituric acid reactive substances(TBARS) increased, while polyunsaturated fatty acids(PUFA) content, amino acid content, and L*, W*, and b*values decreased, with varying degrees of wrinkles and cracks appearing on the surface of flaxseed, and the overall signal pattern of FTIR spectra did not change much. During the 40℃ accelerated storage process, the quality of flaxseed treated by all three preheating methods generally declined, and correlation analysis revealed that color change was a good indicator of quality changes in flaxseed. Notably, all three pretreatment methods extended the shelf-life of flaxseed. Compared with steaming(120℃ for 20 min) and roasting(100℃ for 40 min), microwave(560 W for 4 min) is recommended to remove cyanogenic glycosides and improve the stability and quality characteristics of flaxseed.展开更多
Simultaneous degradation and detoxification during pharmaceutical and personal care product removal are important for water treatment.In this study,sodium niobate nanocubes decorated with graphitic carbon nitride(NbNC...Simultaneous degradation and detoxification during pharmaceutical and personal care product removal are important for water treatment.In this study,sodium niobate nanocubes decorated with graphitic carbon nitride(NbNC/g-C_(3)N_(4))were fabricated to achieve the efficient photocatalytic degradation and detoxification of ciprofloxacin(CIP)under simulated solar light.NaNbO_(3)nanocubes were in-situ transformed from Na_(2)Nb_(2)O_(6)·H_(2)O via thermal dehydration at the interface of g-C_(3)N_(4).The optimized NbNC/g-C_(3)N_(4)-1 was a type-I heterojunction,which showed a high conduction band(CB)level of−1.68 eV,leading to the efficient transfer of photogenerated electrons to O_(2) to produce primary reactive species,•O_(2)^(-).Density functional theory(DFT)calculations of the density of states indicated that C 2p and Nb 3d contributed to the CB,and 0.37 e^(-)transferred from NaNbO_(3)to g-C_(3)N_(4)in NbNC/g-C_(3)N_(4)based on the Mulliken population analysis of the built-in electric field intensity.NbNC/g-C_(3)N_(4)-1 had 3.3-and 2.3-fold of CIP degradation rate constants(k_(1)=0.173 min^(−1))compared with those of pristine g-C_(3)N_(4)and NaNbO_(3),respectively.In addition,N24,N19,and C5 in CIP with a high Fukui index were reactive sites for electrophilic attack by•O_(2)^(-),resulting in the defluorination and ring-opening of the piperazine moiety of the dominant degradation pathways.Intermediate/product identification,integrated with computational toxicity evaluation,further indicated a substantial detoxification effect during CIP degradation in the photocatalysis system.展开更多
Zearalenone(ZEN)is a non-steroidal estrogenic mycotoxin biosynthesized by the polyketide reaction,which has estrogenic effects and triggers toxic effects,such as reproductive toxicity,hepatotoxicity,genotoxicity,and i...Zearalenone(ZEN)is a non-steroidal estrogenic mycotoxin biosynthesized by the polyketide reaction,which has estrogenic effects and triggers toxic effects,such as reproductive toxicity,hepatotoxicity,genotoxicity,and immunotoxicity in organism.Due to its impact on human and animal health and the economic losses engendered by ZEN,detoxification strategies for contaminated foods and feeds to reduce or eliminate the toxic effects of ZEN by chemical,physical and biological methods are crucial.Detoxification by microbial means has broad application prospects,with the advantages of high efficiency,high specificity,mild conditions of action,no harmful metabolites,and safety.It may help to improve the function of intestinal barriers so that the intestinal epithelial barrier is more resistant to mycotoxins,and other pathogenic microorganisms.This article provided an overview of the metabolic pathways and animal toxicity of ZEN in organism,and summarized the effects of the current research status,detoxification mechanisms and in vivo applications of ZEN biodetoxification,in order to provide a reference for the prevention and control of ZEN.展开更多
Understanding bacterial strategies for coping with heavy metal stress is essential for elucidating their resilience in contaminated environments.However,whether cell wall exfoliation contributes to bacterial tolerance...Understanding bacterial strategies for coping with heavy metal stress is essential for elucidating their resilience in contaminated environments.However,whether cell wall exfoliation contributes to bacterial tolerance under heavy metal stress,such as cadmium(Cd)exposure,remains unclear and requires further investigation.In this study,we reveal a novel self-protective mechanism in Stenotrophomonas sp.H225 isolated from a Cd-contaminated farmland soil,which underwent controlled cell wall exfoliation and regeneration in response to Cd stress up to 200 mg L^(-1).Transmission electron microscopy and energy-dispersive X-ray spectroscopy analyses revealed that the exfoliated cell wall fragments served as extracellular Cd sinks,thereby reducing intracellular Cd accumulation.Fourier-transform infrared spectroscopy and enzyme-linked immunosorbent assay indicated progressive peptidoglycan(PG)degradation,with exfoliated PG concentration in solution increasing from 148 ng mL^(-1) at 0 mg L^(-1) Cd to 240 ng mL^(-1) at 200 mg L^(-1) Cd.This degradation was counteracted by the compensatory upregulation of PG biosynthesis genes,with the enrichment ratio reaching up to 0.83,facilitating cell wall reconstruction.Transcriptomic analysis and gene knockout experiments identified mtgA(encoding a monofunctional transglycosylase)as a key determinant in cell wall repair and Cd resistance.To our knowledge,this is the first mechanistic evidence that bacteria can mitigate heavy metal toxicity through dynamic cell wall remodeling involving exfoliation and regeneration.This finding enhances our understanding of microbial survival strategies under environmental stress and highlights potential targets for engineering metal-tolerant strains for bioremediation applications.展开更多
RNA contains diverse post-transcriptional modifications,and its catabolic breakdown yields numerous modified nucleosides requiring correct processing,but the mechanisms remain unknown.Here,we demonstrate that three RN...RNA contains diverse post-transcriptional modifications,and its catabolic breakdown yields numerous modified nucleosides requiring correct processing,but the mechanisms remain unknown.Here,we demonstrate that three RNA-derived modified adenosines,N6-methyladenosine(m6A),N6,N6-dimethyladenosine(m6,6A),and N6-isopentenyladenosine(i6A),are sequentially metabolized into inosine monophosphate(IMP)to mitigate their intrinsic cytotoxicity.展开更多
基金supported by the Chinese Natural Science Foundation Projects 32072775,32272915 and 32472949the National Key Research and Development Programs of China(2023YFD1301003 and 2023YFD1301005)the Fundamental Research Funds for the Central Universities(2662023DKPY002)。
文摘Background AFB_(1)-8,9-exo-epoxide(AFBO)is the highly toxic product of Aflatoxin B_(1)(AFB_(1)).Glutathione S-transferases(GSTs)play pivotal roles in detoxifying AFB_(1) by catalyzing the conjugation of AFBO with glutathione(GSH).Although there are over 20 GST isozymes that have been identified in chicken,GST isozymes involved in the detoxification process of AFB_(1) have not been identified yet.The objective of this study was to determine which GST isozymes played key role in detoxification of AFB_(1).Results A total of 17 pcDNA3.1(+)-GST isozyme plasmids were constructed and the GST isozyme genes were overexpressed by 80–2,500,000 folds in the chicken Leghorn male hepatoma(LMH)cells.Compared to the AFB_(1) treatment,overexpression of GSTA2X,GSTA3,GSTT1L,GSTZ1-1,and GSTZ1-2 increased the cell viability by 6.5%–17.0%in LMH cells.Moreover,overexpression of five GST isozymes reduced the release of lactate dehydrogenase and reactive oxygen species by 8.8%–64.4%,and 57.2%–77.6%,respectively,as well as enhanced the production AFBO-GSH by 15.8%–19.6%,thus mitigating DNA damage induced by AFB_(1).After comprehensive evaluation of various indicators,GSTA2X displayed the best detoxification effects against AFB_(1).GSTA2X was expressed in Pichia pastoris X-33 and its enzymatic properties for catalyzing the conjugation of AFBO with GSH showed that the optimum temperature and pH were 20–25℃ and 7.6–8.6 as well as the enzymatic kinetic parameter V_(max) was 0.23 nmol/min/mg and the Michaelis constant was 86.05μmol/L with the AFB_(1) as substrate.Conclusions In conclusion,GSTA2X,GSTA3,GSTT1L,GSTZ1-1,and GSTZ1-2 played key roles in AFB_(1) detoxification,which will provide new remediation strategies to prevent aflatoxicosis in chickens.
基金Dalian Science and Technology Innovation Fund Project (2022JJ11CG008)。
文摘Aiming to provide a theoretical basis for possible uses of flaxseed as a food supplement and functional ingredient, the heat treatment of flaxseed was carried out using steaming, roasting, and microwave methods to investigate the detoxification effects of these three pretreatment methods on flaxseed, as well as the impact of the three methods on the quality of flaxseed. The results showed that all three pretreatment methods had better detoxification effects on flaxseed, in which, microwave treatment was the most effective method. After 5 min of microwave treatment, the hydrogen cyanide(HCN) content in flaxseed decreased from(94.65±1.68) mg/kg to(7.80±0.57) mg/kg. All three pretreatment methods significantly reduced the water content in flaxseed but had a weaker effect on protein, fat, and ash contents. After pretreatment by the three methods, the polyphenol content, peroxide value(POV), and a*value of flaxseed increased significantly, thiobarbituric acid reactive substances(TBARS) increased, while polyunsaturated fatty acids(PUFA) content, amino acid content, and L*, W*, and b*values decreased, with varying degrees of wrinkles and cracks appearing on the surface of flaxseed, and the overall signal pattern of FTIR spectra did not change much. During the 40℃ accelerated storage process, the quality of flaxseed treated by all three preheating methods generally declined, and correlation analysis revealed that color change was a good indicator of quality changes in flaxseed. Notably, all three pretreatment methods extended the shelf-life of flaxseed. Compared with steaming(120℃ for 20 min) and roasting(100℃ for 40 min), microwave(560 W for 4 min) is recommended to remove cyanogenic glycosides and improve the stability and quality characteristics of flaxseed.
基金the National Key Research and Development Program of China(Nos.2021YFA1202500 and 2022YFF1303004)Shenzhen Science and Technology Program(No.JCYJ20220531093205013)+6 种基金the National Natural Science Foundation of China(NSFC)(Nos.52100069,52270053 and 52200084)the Beijing Natural Science Foundation(No.8232035),the Beijing Nova Program(No.20220484215)the Beijing National Laboratory for Molecular Sciences(No.BNLMS2023011)Emerging Engineering Interdisciplinary-Young Scholars Project(Peking University),the Fundamental Research Funds for the Central Universities are greatly acknowledgedsupported by the High-Performance Computing Platform of Peking Universitythe National Key Scientific and Technological Infrastructure project“Earth System Numerical Simulation Facility”(EarthLab)are also acknowledgedsupported by the program of“Research on Advanced Treatment Technology of New Pollutants in Domestic Sewage of Residential District”.
文摘Simultaneous degradation and detoxification during pharmaceutical and personal care product removal are important for water treatment.In this study,sodium niobate nanocubes decorated with graphitic carbon nitride(NbNC/g-C_(3)N_(4))were fabricated to achieve the efficient photocatalytic degradation and detoxification of ciprofloxacin(CIP)under simulated solar light.NaNbO_(3)nanocubes were in-situ transformed from Na_(2)Nb_(2)O_(6)·H_(2)O via thermal dehydration at the interface of g-C_(3)N_(4).The optimized NbNC/g-C_(3)N_(4)-1 was a type-I heterojunction,which showed a high conduction band(CB)level of−1.68 eV,leading to the efficient transfer of photogenerated electrons to O_(2) to produce primary reactive species,•O_(2)^(-).Density functional theory(DFT)calculations of the density of states indicated that C 2p and Nb 3d contributed to the CB,and 0.37 e^(-)transferred from NaNbO_(3)to g-C_(3)N_(4)in NbNC/g-C_(3)N_(4)based on the Mulliken population analysis of the built-in electric field intensity.NbNC/g-C_(3)N_(4)-1 had 3.3-and 2.3-fold of CIP degradation rate constants(k_(1)=0.173 min^(−1))compared with those of pristine g-C_(3)N_(4)and NaNbO_(3),respectively.In addition,N24,N19,and C5 in CIP with a high Fukui index were reactive sites for electrophilic attack by•O_(2)^(-),resulting in the defluorination and ring-opening of the piperazine moiety of the dominant degradation pathways.Intermediate/product identification,integrated with computational toxicity evaluation,further indicated a substantial detoxification effect during CIP degradation in the photocatalysis system.
基金Supported by China Agriculture Research System(CARS-35)the Natural Science Foundation of Heilongjiang Province of China(LH2021C038)。
文摘Zearalenone(ZEN)is a non-steroidal estrogenic mycotoxin biosynthesized by the polyketide reaction,which has estrogenic effects and triggers toxic effects,such as reproductive toxicity,hepatotoxicity,genotoxicity,and immunotoxicity in organism.Due to its impact on human and animal health and the economic losses engendered by ZEN,detoxification strategies for contaminated foods and feeds to reduce or eliminate the toxic effects of ZEN by chemical,physical and biological methods are crucial.Detoxification by microbial means has broad application prospects,with the advantages of high efficiency,high specificity,mild conditions of action,no harmful metabolites,and safety.It may help to improve the function of intestinal barriers so that the intestinal epithelial barrier is more resistant to mycotoxins,and other pathogenic microorganisms.This article provided an overview of the metabolic pathways and animal toxicity of ZEN in organism,and summarized the effects of the current research status,detoxification mechanisms and in vivo applications of ZEN biodetoxification,in order to provide a reference for the prevention and control of ZEN.
基金partially supported by the National Natural Science Foundation of China (Nos. 42377004 and 41991334)the Fundamental Research Funds for the Central Universities (No. 226-2025-0004)+1 种基金the China Agriculture Research System (No. CARS-01)the opportunity granted by the China Scholarship Council (No. 202406320448)
文摘Understanding bacterial strategies for coping with heavy metal stress is essential for elucidating their resilience in contaminated environments.However,whether cell wall exfoliation contributes to bacterial tolerance under heavy metal stress,such as cadmium(Cd)exposure,remains unclear and requires further investigation.In this study,we reveal a novel self-protective mechanism in Stenotrophomonas sp.H225 isolated from a Cd-contaminated farmland soil,which underwent controlled cell wall exfoliation and regeneration in response to Cd stress up to 200 mg L^(-1).Transmission electron microscopy and energy-dispersive X-ray spectroscopy analyses revealed that the exfoliated cell wall fragments served as extracellular Cd sinks,thereby reducing intracellular Cd accumulation.Fourier-transform infrared spectroscopy and enzyme-linked immunosorbent assay indicated progressive peptidoglycan(PG)degradation,with exfoliated PG concentration in solution increasing from 148 ng mL^(-1) at 0 mg L^(-1) Cd to 240 ng mL^(-1) at 200 mg L^(-1) Cd.This degradation was counteracted by the compensatory upregulation of PG biosynthesis genes,with the enrichment ratio reaching up to 0.83,facilitating cell wall reconstruction.Transcriptomic analysis and gene knockout experiments identified mtgA(encoding a monofunctional transglycosylase)as a key determinant in cell wall repair and Cd resistance.To our knowledge,this is the first mechanistic evidence that bacteria can mitigate heavy metal toxicity through dynamic cell wall remodeling involving exfoliation and regeneration.This finding enhances our understanding of microbial survival strategies under environmental stress and highlights potential targets for engineering metal-tolerant strains for bioremediation applications.
文摘RNA contains diverse post-transcriptional modifications,and its catabolic breakdown yields numerous modified nucleosides requiring correct processing,but the mechanisms remain unknown.Here,we demonstrate that three RNA-derived modified adenosines,N6-methyladenosine(m6A),N6,N6-dimethyladenosine(m6,6A),and N6-isopentenyladenosine(i6A),are sequentially metabolized into inosine monophosphate(IMP)to mitigate their intrinsic cytotoxicity.
