There are two formation routes of dietary N-nitrosamines:exogenous and endogenous formation.The formation of N-nitrosamines from either source requires precursors with a dialkylamine functional group and a nitrosating...There are two formation routes of dietary N-nitrosamines:exogenous and endogenous formation.The formation of N-nitrosamines from either source requires precursors with a dialkylamine functional group and a nitrosating agent.Precursors are supplied primarily by amine-rich foods and nitrosating agents are nitrite or its reaction products(N_(2)O_(3) and NO^(+)).Unprocessed fresh foods initially contain zero or only trace amounts of N-nitrosamines while significant amounts of N-nitrosamines can be generated during certain types of food processing.Cooking methods,pH,additives,and storage conditions can affect the formation of N-nitrosamines in foods.We analysed the formation mechanisms/pathways of the three most frequently detected N-nitrosamines in processed meats.Formation of endogenous N-nitrosamines is likely to be greater than that of exogenous N-nitrosamines.Nitrosating agents involved in the formation of endogenous N-nitrosamines are formed from nitrate in vegetables via the nitrate-nitrite-NO cycle.N-nitrosamines are produced in the human stomach and intestine but their formation mechanisms differ.We analysed the mechanism/pathway for the formation of N-nitrosotryptophan from tryptophan in the stomach.The formation of N-nitrosamines in the intestine includes both chemical and microbiological mechanisms.In addition to N-nitrosation,S-nitrosation also occurs in the human body.There is a competitive relationship between the two reactions,and S-nitrosation is more likely to occur in the healthy human body.This paper reviews the mechanisms and factors influencing the formation of exogenous and endogenous dietary N-nitrosamines,which illustrate the importance of microbial-mediated N-nitrosamine formation and the production of endogenous N-nitrosamines.展开更多
This article presents an adaptive optimal control method for a semi-active suspension system.The model of the suspension system is built,in which the components of uncertain parameters and exogenous disturbance are de...This article presents an adaptive optimal control method for a semi-active suspension system.The model of the suspension system is built,in which the components of uncertain parameters and exogenous disturbance are described.The adaptive optimal control law consists of the sum of the optimal control component and the adaptive control component.First,the optimal control law is designed for the model of the suspension system after ignoring the components of uncertain parameters and exogenous disturbance caused by the road surface.The optimal control law expresses the desired dynamic characteristics of the suspension system.Next,the adaptive component is designed with the purpose of compensating for the effects caused by uncertain parameters and exogenous disturbance caused by the road surface;the adaptive component has adaptive parameter rules to estimate uncertain parameters and exogenous disturbance.When exogenous disturbances are eliminated,the system responds with an optimal controller designed.By separating theoretically the dynamic of a semi-active suspension system,this solution allows the design of two separate controllers easily and has reduced the computational burden and the use of too many tools,thus allowing for more convenient hardware implementation.The simulation results also show the effectiveness of damping oscillations of the proposed solution in this article.展开更多
BACKGROUND Exogenous insulin may trigger immune-mediated complications,particularly among East Asian populations.Double diabetes,characterized by overlapping features of type 1 diabetes(T1D)and type 2 diabetes(T2D),ma...BACKGROUND Exogenous insulin may trigger immune-mediated complications,particularly among East Asian populations.Double diabetes,characterized by overlapping features of type 1 diabetes(T1D)and type 2 diabetes(T2D),may arise from insulin-induced autoimmunity.This study aimed to explore the association between high-risk human leukocyte antigen(HLA)class Ⅱ genotypes and susceptibility to double diabetes in patients initially diagnosed with T2D.AIM To investigate clinical and immunogenic features of patients who develop double diabetes following exogenous insulin therapy.METHODS We retrospectively analyzed five cases from Peking Union Medical College Hospital and 18 cases identified from published literature.Patients were categorized into two groups:The T2D→T1D group,characterized by autoimmune progression,and the stable T2D(T2D→T2D).Clinical characteristics and HLA class Ⅱ genotypes were compared descriptively between the two groups.RESULTS A total of 23 patients were included in the analysis.Of these,10 progressed from theT2D→T1D with autoimmune features,while 13 remained in the stable T2D→T2D group.There was no statistically significant difference in age at diagnosis between the two groups(57.10±16.11 years vs 60.31±17.41 years).In the T2D→T1D group,70%of patients carried the HLA-DRB104:05 allele and 40%carried DRB109:01,both of which are commonly associated with a high risk of T1D.In contrast,the T2D→T2D group showed greater genetic heterogeneity,with a broader distribution of HLA-DRB1 alleles,including DRB103:02(n=4),DRB109:01(n=4),and several lower frequency alleles such as DRB1*04:05,*08:03,*03:01,*04:06,*14:01,*04:01,*12:02,*15:02 and*02:01.CONCLUSION These findings suggest that patients in the T2D→T1D group exhibit a stronger autoimmune genetic predisposition,characterized by an enrichment of high-risk HLA class II alleles.In contrast,individuals with stable T2D demonstrate greater HLA diversity and lack definitive autoimmune-associated markers.展开更多
Alzheimer’s disease(AD)is a neurodegenerative disease causing the most frequent form of dementia in old age.AD etiology is still uncertain and deposition of abnormal proteins in the brain along with chronic neuroinfl...Alzheimer’s disease(AD)is a neurodegenerative disease causing the most frequent form of dementia in old age.AD etiology is still uncertain and deposition of abnormal proteins in the brain along with chronic neuroinflammation have been suggested as pathogenic mechanisms of neuronal death.Infections by exogenous neurotropic virus,endogenous retrovirus reactivation,infections by other microbes,and air pollutants may either induce neurodegeneration or activate brain inflammation.Up to 8%of the human genome has a retroviral origin.These ancient retroviruses,also called human endogenous retroviruses,are associated with a clinical history of several neurodegenerative diseases.Under persistent stress,such as chronic infections and inflammation,neurons,and microglia cells may enter a state of division inactivation called cell senescence.Senescent cells are resistant to apoptosis and can release pro-inflammatory molecules promoting the functional decline of tissues and organs and also activate silent viruses.Infections andmutations induced by pollutants can lead to the expression of different endogenous retroviruses,which may contribute to several different diseases,including AD-associated neurodegeneration.Here I discuss that infection by exogenous pathogen,activation of endogenous retrovirus or retrotransposons and pollutants might induce neuronal senescence and cause persistent brain neurodegeneration.Therefore,cell senescence appears to be an emerging mechanism that might contribute to AD neurodegeneration.Finally,treatment of AD patients with senolytic drugs,e.g.,compounds able to kill senescent cells,might show a positive effect on AD progression.展开更多
Rice(Oryza sativa L.)root characteristics are closely associated with nitrogen(N)uptake,root growth and development are greatly influenced by ethylene.In this study,a hydroponic experiment was conducted using four ric...Rice(Oryza sativa L.)root characteristics are closely associated with nitrogen(N)uptake,root growth and development are greatly influenced by ethylene.In this study,a hydroponic experiment was conducted using four rice genotypes[Shanyou 63(SY63)and Zhonghua 11(ZH11)with well–developed aerenchyma;Yangdao 6(YD6)and mutant rcn1 from ZH11 with less–developed aerenchyma]to investigate the effects of exogenous ethephon(Eth)on root characteristics,N uptake,dry matter distribution,and clarify the underlying relationship.Compared with YD6 and rcn1,SY63 and ZH11 had higher N accumulation,higher root aerenchyma area to cortex area ratio(ACR),higher NH_(4)^(+)uptake via the apoplasmic pathway and root-to-shoot NH_(4)^(+)translocation under no ethephon application(NEth)and Eth treatment,and elevated expression of the three genes(OsAMT1;2,OsAMT2;2,and OsAMT4;1)for ammonium transporters under Eth treatment.Eth treatment increased shoot N and dry matter accumulation,decreased the total root length and root diameter,and increased ACR and the expression of OsAMT genes in four genotypes.In summary,Eth could increase N accumulation via modifying root characteristics in rice,particularly by enlarging root aerenchyma and thinning the roots.The findings provide implications for development of elite rice varieties and green rice production with higher N efficiency.展开更多
CRISPR-based tran-scription regulators(CRISPR-TRs)have revolutionized the field of synthetic biol-ogy by enabling tar-geted activation or repression of any de-sired gene.However,the majority of exist-ing inducible CRI...CRISPR-based tran-scription regulators(CRISPR-TRs)have revolutionized the field of synthetic biol-ogy by enabling tar-geted activation or repression of any de-sired gene.However,the majority of exist-ing inducible CRISPR-TRs are limited by their dependence on specific sequences,which restricts their flex-ibility and controllability in genetic engineering applications.In this study,we proposed a novel strategy to construct sequence-independent inducible CRISPR-TRs,which is achieved by the design of stem loop 2 in the single guide RNA(sgRNA).Under this strategy,by utiliz-ing toehold-mediated strand displacement(TMSD)reactions between small endogenous molecules(miR-20a and TK1 mRNA)and bridge RNA(bRNA)to link bRNA with sgRNA,we achieved synergistic transcriptional activation of VP64 and p65-HSF1 in response to en-dogenous molecules.To enable response to exogenous molecules,we added response se-quences and bRNA sequences to the 5'end of sgRNA to block sgRNA activity,and achieved activation of sgRNA by shearing the response sequence,called sequential unlimited interlock-ing(SUI).Compared with conventional sequence-restricted interlocking(spacer-blocking hairpin(SBH)),the transcriptional activation ratio between response and non-response to the Cas6A protein using our approach was increased by 2.28-fold.Our work presents a modular and versatile framework for endogenous and exogenous molecule-responsive CRISPR-TRs in mammalian cells,without limitations imposed by sequence dependence.展开更多
[Objective] The research aimed to map QTL for the sensitivity of the traits related outcrosssing of Japonica rice to exogenous GA3 and provide theoretical basis for breeding and improving the high-sensitivity sterile ...[Objective] The research aimed to map QTL for the sensitivity of the traits related outcrosssing of Japonica rice to exogenous GA3 and provide theoretical basis for breeding and improving the high-sensitivity sterile line.[Method] Taking Japonica rice Xiushui 79 and C bao and their recombinant inbred line population 260 lines as test materials,the sensitivity of 4 traits related outcrossing to Exogenous GA3 and their QTL mapping were studied by using composite interval mapping..[Result]Three QTLs,which cont...展开更多
Objective The purpose of this experiment was to investigate the effects of exogenous hormone factors on subculture multiplication and root induction of tis-suecultured seedlings in mulberry. [Method] The aseptic seedl...Objective The purpose of this experiment was to investigate the effects of exogenous hormone factors on subculture multiplication and root induction of tis-suecultured seedlings in mulberry. [Method] The aseptic seedlings of Guisangyou 12 were used as the materials and the comparative experiment on subculture multi-plication and root induction used different kinds,concentrations and combinations of exogenous hormones. [Result] The hormone combination of 0.1 mg/L IBA＋1.5 mg/L 6-BA＋0.03 mg/L TDZ showed the best effects to bud multiplication, and the multiple of bud multiplication was 5.28. The effects of NAA was better than IBA and IAA on root induction. The hormone combination of 2.0 mg/L NAA＋1.0 mg/L PP333 was most suitable to the root induction, in which the rooting rate arrived to 100%, the root number was 7.01 and the root length was 1.38 cm on average. [Conclusion] The results wil provide some technical reference for large-scale propagation of mul-berry seedlings in vitro.展开更多
The content of total sugar, sucrose, fructose and protein in the leaves of3-yr.-old Betula platyphylla was measured after the treatment by three exogenous sugar solutions(sucrose, fructose, glucose) and three high con...The content of total sugar, sucrose, fructose and protein in the leaves of3-yr.-old Betula platyphylla was measured after the treatment by three exogenous sugar solutions(sucrose, fructose, glucose) and three high concentrations of CO_2 (700, 1 400, 2 100 μL/L·L^(-1))for about a month in 1998. The results showed that spraying three exogenous sugar solutionsincreased markedly the content of sugar and protein of leaves under 700 μL·L^(-1) and 1 400μL·L^(-1) CO_2 The effect of spraying exogenous sucrose solution was the best among the threeexogenous sugars. The treatment of spraying exogenous sugar solution and 2 100 μL·L^(-1) CO_2constrained the accumulation of total sugar and protein of leaves. There was no difference inprotein content of leaves when spraying glucose and fructose solutions under 700 μL·L^(-1) and 1400 μL·L^(-1) CO_2. The treatment of 2 100 μL·L^(-1) CO_2 concentration significantly increasedthe contents of total sugar, sucrose, fructose, and protein of leaves compared with that of the 700μL·L^(-1) and 1 400 μL·L^(-1) CO_2 except the plants spraying fructose solution. There waspositive correlation between the content of sugar of leaves and CO_2 concentration when sprayingsame exogenous sugar solution.展开更多
[Objective] This study was conducted to reveal the effect of exogenous calcium （Ca） in mitigating the damage caused by NaCI stress to watermelon seedlings. [Method] To the liquid medium containing 100 mmol/L NaCI, C...[Objective] This study was conducted to reveal the effect of exogenous calcium （Ca） in mitigating the damage caused by NaCI stress to watermelon seedlings. [Method] To the liquid medium containing 100 mmol/L NaCI, CaSO4 was added to the final concentrations of 4, 6, 10 and 14 mmol/L. The morphological and physiological indices including plant height, stem diameter, number of leaves per plant, maximum leaf length, maximum leaf width, seedling fresh weight and dry weight, malondialdehyde （MDA） content, relative permeability of plasma membrane, ascorbic acid （AsA） content, free proline content, soluble sugar content and soluble protein content in leaves of the seedlings treated with above media for 10 d were measured. [Result] NaCI stress significantly inhibited the growth of watermelon seedlings. The membrane permeability and MDA content in leaves were significantly increased under NaCI stress, and the contents of proline, soluble sugar, soluble protein and AsA were increased to different extents. Exogenous CaSO4 influenced the morphological and physiological indices of seedlings under NaCI stress in a manner. Treated with 6 mmol/L CaSO4, the growth of seedlings under salinity was significantly improved; membrane permeability and MDA content were drastically reduced, the contents of proline, soluble sugar, soluble pro- tein and AsA in leaves were significantly increased. [Conclusion] Exogenous CaSO＋ alleviates lipid peroxidation and inhibition of seedling growth under NaCI stress by improving the abilities of antioxidation and osmotic adjustment, and 6 mmol/L CaSO4 showed the best effect.展开更多
[Objective] The paper was to study the effects of exogenous GA3 on seed germination and seedling growth of Salicornia europaea L.under salt stress.[Method] With the combination of different concentrations of NaCl（50,...[Objective] The paper was to study the effects of exogenous GA3 on seed germination and seedling growth of Salicornia europaea L.under salt stress.[Method] With the combination of different concentrations of NaCl（50,100,150,200,250,300,350,400 mmol/L）with 10 μmol /L GA3 treatments,the effects of exogenous GA3 on seed germination and seedling growth of S.europaea under salt stress were studied.[Result] Exogenous GA3 promoted the seed germination rate,germination capacity,germination index and seed vigor index of S.europaea under salt stress.Under the treatment of exogenous GA3,the root system vigor,the lengths of roots and stems and the salt-tolerance of S.europaea were higher than that of single salt stress treatment.[Conclusion] Within a certain concentration range,exogenous GA3 could alleviate the inhibition effects of salt stress on seed germination and seedling growth of S.europaea.展开更多
The mechanisms of sex determination and the influence of exogenous factors on sex differentiation in crustacean were reviewed in the paper.Most of crustecea have not obviously sex chromosome.Androgenic gland was repor...The mechanisms of sex determination and the influence of exogenous factors on sex differentiation in crustacean were reviewed in the paper.Most of crustecea have not obviously sex chromosome.Androgenic gland was reported as the most important sex differentiation factors,implanting or cuting AG can change the sexal characterization of larval in crustacean.Although sex differentiation of crustacean is determined by gene,it is affected by exogenous factors such as parasite,photoperiod,temperature or hormone.Most cultured species have different body weight and length between male and female,this can be used in aquaculture to produce all male or female crusteceans to improve the production.展开更多
Objective] The aim of this study was to investigate the effects of exoge-nous amylases and Ca2＋, Mn2＋ and K＋ on the amylase specific activities and starch degradation of the upper leaves of ＇KRK26＇ planted in Yun...Objective] The aim of this study was to investigate the effects of exoge-nous amylases and Ca2＋, Mn2＋ and K＋ on the amylase specific activities and starch degradation of the upper leaves of ＇KRK26＇ planted in Yunnan Province during flue-curing. [Method] The amylase specific activities and starch degradation of the leaves were determined by using spectrophotometry. [Result] The 8 U/g exogenous α-amy-lase could improve the specific activity of the leaf α-amylase at yel owing and color-fixing stages, but could not at stem-drying stage, and similarly, the 80 U/g exoge-nous β-amylase could improved the specific activity of the leaf β-amylase at the yel owing stage and the early period of color-fixing stage. The leaf starch could be enhanced to degrade by the exogenous α- or β-amylases and the enhancing effect of the former was stronger than that of the later. 1.50 mg/ml Ca2＋ improved the specific activity of the leaf （α＋β）-amylase mainly due to its enhancing effect on the leaf α-amylase, and increased the starch degradation. 4 mmol/L Mn2＋ inhibited the leaf α-amylase from yel owing to the early period of color-fixing and the β- and （α＋β）-amylases from the yel owing to the later period of color-fixing, but enhanced the leafα-amylase from the later period of color-fixing to the later period of stem-drying and the β- and （α＋β）-amylases at the later period of stem-drying. Meanwhile, Mn2＋ ham-pered the starch degradation during yel owing, but promoted it from the early period of color-fixing to stem-drying. 1 mg/ml K＋ enhanced the leaf α-, β- and （α＋β）-amy-lases during the yel owing stage, but lowered them from the early period of color-fix-ing to the later period of stem-drying, and always inhibited the leaf starch degrada-tion. [Conclusion] The exogenous α-, β- amylases and Ca2＋ of suitable concentra-tions could be used to treat the tobacco leaves before flue-curing to improve the leaf starch degradation during the curing.展开更多
The effects of exogenous growth regulating substance on the fruit weight of peach were reviewed. Paclobutrazol could increase the single fruit weight in dif- ferent degree, and cytokinins could also increase the singl...The effects of exogenous growth regulating substance on the fruit weight of peach were reviewed. Paclobutrazol could increase the single fruit weight in dif- ferent degree, and cytokinins could also increase the single fruit weight. GA3 and B9 had no effect on fruit size or on reducing single fruit weight. Chlorflurenol-methy, ABT and salicylic acid had no effect on fruit size. Suggestions on the future re- search were put forward.展开更多
The growth and yield of peanut are negatively affected by continuous cropping.Arbuscular mycorrhizal fungi(AMF)and calcium ions(Ca^(2+))have been used to improve stress resistance in other plants,but little is known a...The growth and yield of peanut are negatively affected by continuous cropping.Arbuscular mycorrhizal fungi(AMF)and calcium ions(Ca^(2+))have been used to improve stress resistance in other plants,but little is known about their roles in peanut seedling growth under continuous cropping.This study investigated the possible roles of the AMF Glomus mosseae combined with exogenous Ca^(2+)in improving the physiological responses of peanut seedlings under continuous cropping.G.mosseae combined with exogenous Ca^(2+)can enhance plant biomass,Ca^(2+)level,and total chlorophyll content.Under exogenous Ca^(2+)application,the F_v/F_m in arbuscular mycorrhizal(AM)plant leaves was higher than that in the control plants when they were exposed to high irradiance levels.The peroxidase,superoxide dismutase,and catalase activities in AM plant leaves also reached their maximums,and accordingly,the malondialdehyde content was the lowest compared to other treatments.Additionally,root activity,and content of total phenolics and flavonoids were significantly increased in AM plant roots treated by Ca^(2+)compared to either G.mosseae inoculation or Ca^(2+)treatment alone.Transcription levels of AhCaM,AhCDPK,AhRAM1,and AhRAM2 were significantly improved in AM plant roots under exogenous Ca^(2+)treatment.This implied that exogenous Ca^(2+)might be involved in the regulation of G.mosseae colonization of peanut plants,and in turn,AM symbiosis might activate the Ca^(2+)signal transduction pathway.The combination of AMF and Ca^(2+)benefitted plant growth and development under continuous cropping,suggesting that it is a promising method to cope with the stress caused by continuous cropping.展开更多
Drought at the grain filling stage of wheat will cause premature leaf senescence, thus leading to considerable loss of wheat yield. Therefore, this paper aims to establish a cultivation technology for strong drought r...Drought at the grain filling stage of wheat will cause premature leaf senescence, thus leading to considerable loss of wheat yield. Therefore, this paper aims to establish a cultivation technology for strong drought resistance, delayed senescence, and yield improvement based on the analysis of hormones homeostasis obtained by applying chemical control substances. Experiments were conducted with two genotypes of wheat. Four water irrigation treatments were applied to impose the water deficit, including well-watered control treatment(WW), mild water deficit(MiWD), moderate water deficit(MoWD), and severe water deficit(SWD). Exogenous abscisic acid(ABA) was sprayed on the plants at the anthesis stage of the wheat. As a result, exogenous ABA reduced initial senescence rate(r0), total duration of chlorophyll(Chltotal), rapid senescence phase(Chlloss), and the accumulated temperature at an inflection point(M) but improved the persistence phase(Chlper) of flag leaves under all of the four treatments. However, exogenous ABA produced inconsistent effects on photoassimilate relocation and grain weight under different treatments. It produced positive regulatory effects on grain weight under WW, MiWD, and MoWD treatments. On the one hand, spraying ABA during the persistence phase of flag leaves reduced the ratios of zeatin to gibberellin(Z/GA3), spermine to spermidine(Spm/Spd), and salicylic acid to ABA(SA/ABA),which prolonged active photosynthesis by stimulating high level of proline(Pro) and increased the activities of antioxidant enzymes, such as superoxide dismutase(SOD), peroxidase(POD), catalase(CAT), and ascorbate peroxidase(APX). Therefore, drought tolerance was enhanced, and more photosynthetic assimilates were accumulated. On the other hand, the rapid senescence phase and the transport rate of assimilates into grains were accelerated, resulting in higher grain weight, yield, and water use efficiency(WUE). However, under SWD treatment, exogenous ABA improved the ratio of SA/ABA, leading to low Pro content and low antioxidant enzyme activity of flag leaves in the rapid loss phase. Meanwhile,drought resistance declined and the transport duration of assimilates into grains was shortened, thus making photosynthetic assimilates redundant. Therefore, exogenous ABA can lead to the reduction in grain weight, yield, and WUE of wheat under SWD treatment.展开更多
Decreased expression of brain-derived neurotrophic factor（BDNF） plays an important role in the pathogenesis of Alzheimer＇s disease, and a typical pathological change in Alzheimer＇s disease is neurofibrillary tangl...Decreased expression of brain-derived neurotrophic factor（BDNF） plays an important role in the pathogenesis of Alzheimer＇s disease, and a typical pathological change in Alzheimer＇s disease is neurofibrillary tangles caused by hyperphosphorylation of tau. An in vivo model of Alzheimer＇s disease was developed by injecting okadaic acid（2 μL） and exogenous BDNF（2 μL） into the hippocampi of adult male Wister rats. Spatial learning and memory abilities were assessed using the Morris water maze. The expression levels of protein phosphatase 2 A（PP2 A）, PP2 Ac-Yp307, p-tau（Thr231）, and p-tau（Ser396/404） were detected by western blot assay. The expression levels of BDNF, TrkB, and synaptophysin mRNA were measured by quantitative real-time polymerase chain reaction. Our results indicated that BDNF expression was suppressed in the hippocampus of OA-treated rats, which resulted in learning and memory deficits. Intra-hippocampal injection of BDNF attenuated this OA-induced cognitive impairment. Finally, our findings indicated an involvement of the PI3 K/GSK-3β/AKT pathway in the mechanism of BDNF in regulating cognitive function. These results indicate that BDNF has beneficial effect on Alzheimer＇s disease, and highlight the potential of BDNF as a drug target for treatment of Alzheimer＇s disease.展开更多
Objective Nan'ao County in Guandong Province is a high-risk area of esophageal cancer in Southern China. Of the suspected etiological factors in the environment, N-nitrosamines and their precursors have received t...Objective Nan'ao County in Guandong Province is a high-risk area of esophageal cancer in Southern China. Of the suspected etiological factors in the environment, N-nitrosamines and their precursors have received the greatest attention. Methods Sixty samples of the diet ingested by the inhabitants were collected and detected for volatile N-nitrosamines and their precursors. Five N-nitrosamines detected by Gas Chromatography-Thermal Energy Analyzer were N-nitrosodimethylamine, N-nitrosodiethylamine, N-nitrosopyrrolidine, N-nitrosopiperidine and N-nitrosomethyl-benzylamine. Results The average content of 5 volatile N-nitrosamines in the diet was 312.0 μg/kg (median). The daily intake of the nitrosamines was 286.5 μg/head/day. Only the ability to exogenously synthesize N-nitrosopiperidine was powerful among 5 volatile N-nitrosamines. By a computerized stepwise regression analysis and curve fitting, we studied the correlation among the nitrosamines, the precursors and the major food items in the samples. Conclusion It demonstrated that a relatively high content of volatile N-nitrosamines was present in the diet collected in the area.展开更多
The aim of this study was to evaluate the effect of Lactobacillus acidophilus（LAC）, exogenous enzymes of ZAD（exogenous enzyme preparation） or their combination on feed conversion, and dressing of rabbits fed diffe...The aim of this study was to evaluate the effect of Lactobacillus acidophilus（LAC）, exogenous enzymes of ZAD（exogenous enzyme preparation） or their combination on feed conversion, and dressing of rabbits fed different treatments of sugarcane bagasse（SCB）. Five rations were allotted randomly to five groups of New-Zealand White（NZW） rabbits（n=10） with initial live body weight of（838±42.4） g and 5 weeks of age. Rabbits were fed on diets with different sources of fiber as follows,（i） a control diet composed of 100% berseem hay and 0% SCB,（ii） 50% berseem hay and 50% untreated SCB（USCB）,（iii） 50% berseem hay and 50% SCB treated with L. acidophilus（LAC）,（iv） 50% berseem hay and 50% SCB treated with ZAD（ZAD）, and（v） 50% berseem hay and 50% SCB treated with a combination of LAC＋ZAD（LZ）. Treatments of SCB with L. acidophilus, ZAD and LAC＋ZAD had the highest feed conversion ratio than both USCB and control. The dressing percentage of rabbits that fed the LAC and LZ diets was higher（P〈0.05） compared with that in the other groups. Performance index（PI） for LAC group was improved（P〈0.05） compared to that for the other groups; however, PI for USCB group was the lowest（P〈0.05）. It could be concluded that treating SCB with L. acidophilus, exogenous enzymes of ZAD or their combination improved feed conversion and performance with more positive effects with L. acidophilus than the other treatments.展开更多
Background Sustainable strategies for enteric methane(CH_(4))mitigation of dairy cows have been extensively explored to improve production performance and alleviate environmental pressure.The present study aimed to in...Background Sustainable strategies for enteric methane(CH_(4))mitigation of dairy cows have been extensively explored to improve production performance and alleviate environmental pressure.The present study aimed to investigate the effects of dietary xylooligosaccharides(XOS)and exogenous enzyme(EXE)supplementation on milk production,nutrient digestibility,enteric CH_(4) emissions,energy utilization efficiency of lactating Jersey dairy cows.Forty-eight lactating cows were randomly assigned to one of 4 treatments:(1)control diet(CON),(2)CON with 25 g/d XOS(XOS),(3)CON with 15 g/d EXE(EXE),and(4)CON with 25 g/d XOS and 15 g/d EXE(XOS+EXE).The 60-d experimental period consisted of a 14-d adaptation period and a 46-d sampling period.The enteric CO_(2)and CH_(4) emissions and O2 consumption were measured using two GreenFeed units,which were further used to determine the energy utilization efficiency of cows.Results Compared with CON,cows fed XOS,EXE or XOS+EXE significantly(P<0.05)increased milk yield,true protein and fat concentration,and energy-corrected milk yield(ECM)/DM intake,which could be reflected by the significant improvement(P<0.05)of dietary NDF and ADF digestibility.The results showed that dietary supplementation of XOS,EXE or XOS+EXE significantly(P<0.05)reduced CH_(4) emission,CH_(4)/milk yield,and CH_(4)/ECM.Furthermore,cows fed XOS demonstrated highest(P<0.05)metabolizable energy intake,milk energy output but lowest(P<0.05)of CH_(4) energy output and CH_(4) energy output as a proportion of gross energy intake compared with the remaining treatments.Conclusions Dietary supplementary of XOS,EXE or combination of XOS and EXE contributed to the improvement of lactation performance,nutrient digestibility,and energy utilization efficiency,as well as reduction of enteric CH_(4) emissions of lactating Jersey cows.This promising mitigation method may need further research to validate its long-term effect and mode of action for dairy cows.展开更多
基金supported by the National Natural Science Foundation of China(Nos.22376114 and 22076091)the State Key Joint Laboratory of Environment Simulation and Pollution Control,China(No.21L01ESPC)the Youth Science and Technology Innovation Program of Xiamen Ocean and Fisheries Development Special Funds(No.23YYST062QCB29)。
文摘There are two formation routes of dietary N-nitrosamines:exogenous and endogenous formation.The formation of N-nitrosamines from either source requires precursors with a dialkylamine functional group and a nitrosating agent.Precursors are supplied primarily by amine-rich foods and nitrosating agents are nitrite or its reaction products(N_(2)O_(3) and NO^(+)).Unprocessed fresh foods initially contain zero or only trace amounts of N-nitrosamines while significant amounts of N-nitrosamines can be generated during certain types of food processing.Cooking methods,pH,additives,and storage conditions can affect the formation of N-nitrosamines in foods.We analysed the formation mechanisms/pathways of the three most frequently detected N-nitrosamines in processed meats.Formation of endogenous N-nitrosamines is likely to be greater than that of exogenous N-nitrosamines.Nitrosating agents involved in the formation of endogenous N-nitrosamines are formed from nitrate in vegetables via the nitrate-nitrite-NO cycle.N-nitrosamines are produced in the human stomach and intestine but their formation mechanisms differ.We analysed the mechanism/pathway for the formation of N-nitrosotryptophan from tryptophan in the stomach.The formation of N-nitrosamines in the intestine includes both chemical and microbiological mechanisms.In addition to N-nitrosation,S-nitrosation also occurs in the human body.There is a competitive relationship between the two reactions,and S-nitrosation is more likely to occur in the healthy human body.This paper reviews the mechanisms and factors influencing the formation of exogenous and endogenous dietary N-nitrosamines,which illustrate the importance of microbial-mediated N-nitrosamine formation and the production of endogenous N-nitrosamines.
基金supported in part by the Thai Nguyen University of Technology,Vietnam.
文摘This article presents an adaptive optimal control method for a semi-active suspension system.The model of the suspension system is built,in which the components of uncertain parameters and exogenous disturbance are described.The adaptive optimal control law consists of the sum of the optimal control component and the adaptive control component.First,the optimal control law is designed for the model of the suspension system after ignoring the components of uncertain parameters and exogenous disturbance caused by the road surface.The optimal control law expresses the desired dynamic characteristics of the suspension system.Next,the adaptive component is designed with the purpose of compensating for the effects caused by uncertain parameters and exogenous disturbance caused by the road surface;the adaptive component has adaptive parameter rules to estimate uncertain parameters and exogenous disturbance.When exogenous disturbances are eliminated,the system responds with an optimal controller designed.By separating theoretically the dynamic of a semi-active suspension system,this solution allows the design of two separate controllers easily and has reduced the computational burden and the use of too many tools,thus allowing for more convenient hardware implementation.The simulation results also show the effectiveness of damping oscillations of the proposed solution in this article.
基金Supported by CAMS Innovation Fund for Medical Sciences,No.2021-I2M-1-002Healthcare Quality and Safety Incubation Programme of the Peking Union Medical Foundation,No.XHFY 2406the National High-Level Hospital Clinical Research Funding,No.2022-PUMCH-B-015.
文摘BACKGROUND Exogenous insulin may trigger immune-mediated complications,particularly among East Asian populations.Double diabetes,characterized by overlapping features of type 1 diabetes(T1D)and type 2 diabetes(T2D),may arise from insulin-induced autoimmunity.This study aimed to explore the association between high-risk human leukocyte antigen(HLA)class Ⅱ genotypes and susceptibility to double diabetes in patients initially diagnosed with T2D.AIM To investigate clinical and immunogenic features of patients who develop double diabetes following exogenous insulin therapy.METHODS We retrospectively analyzed five cases from Peking Union Medical College Hospital and 18 cases identified from published literature.Patients were categorized into two groups:The T2D→T1D group,characterized by autoimmune progression,and the stable T2D(T2D→T2D).Clinical characteristics and HLA class Ⅱ genotypes were compared descriptively between the two groups.RESULTS A total of 23 patients were included in the analysis.Of these,10 progressed from theT2D→T1D with autoimmune features,while 13 remained in the stable T2D→T2D group.There was no statistically significant difference in age at diagnosis between the two groups(57.10±16.11 years vs 60.31±17.41 years).In the T2D→T1D group,70%of patients carried the HLA-DRB104:05 allele and 40%carried DRB109:01,both of which are commonly associated with a high risk of T1D.In contrast,the T2D→T2D group showed greater genetic heterogeneity,with a broader distribution of HLA-DRB1 alleles,including DRB103:02(n=4),DRB109:01(n=4),and several lower frequency alleles such as DRB1*04:05,*08:03,*03:01,*04:06,*14:01,*04:01,*12:02,*15:02 and*02:01.CONCLUSION These findings suggest that patients in the T2D→T1D group exhibit a stronger autoimmune genetic predisposition,characterized by an enrichment of high-risk HLA class II alleles.In contrast,individuals with stable T2D demonstrate greater HLA diversity and lack definitive autoimmune-associated markers.
文摘Alzheimer’s disease(AD)is a neurodegenerative disease causing the most frequent form of dementia in old age.AD etiology is still uncertain and deposition of abnormal proteins in the brain along with chronic neuroinflammation have been suggested as pathogenic mechanisms of neuronal death.Infections by exogenous neurotropic virus,endogenous retrovirus reactivation,infections by other microbes,and air pollutants may either induce neurodegeneration or activate brain inflammation.Up to 8%of the human genome has a retroviral origin.These ancient retroviruses,also called human endogenous retroviruses,are associated with a clinical history of several neurodegenerative diseases.Under persistent stress,such as chronic infections and inflammation,neurons,and microglia cells may enter a state of division inactivation called cell senescence.Senescent cells are resistant to apoptosis and can release pro-inflammatory molecules promoting the functional decline of tissues and organs and also activate silent viruses.Infections andmutations induced by pollutants can lead to the expression of different endogenous retroviruses,which may contribute to several different diseases,including AD-associated neurodegeneration.Here I discuss that infection by exogenous pathogen,activation of endogenous retrovirus or retrotransposons and pollutants might induce neuronal senescence and cause persistent brain neurodegeneration.Therefore,cell senescence appears to be an emerging mechanism that might contribute to AD neurodegeneration.Finally,treatment of AD patients with senolytic drugs,e.g.,compounds able to kill senescent cells,might show a positive effect on AD progression.
基金supported by the National Natural Science Foundation of China(31671598).
文摘Rice(Oryza sativa L.)root characteristics are closely associated with nitrogen(N)uptake,root growth and development are greatly influenced by ethylene.In this study,a hydroponic experiment was conducted using four rice genotypes[Shanyou 63(SY63)and Zhonghua 11(ZH11)with well–developed aerenchyma;Yangdao 6(YD6)and mutant rcn1 from ZH11 with less–developed aerenchyma]to investigate the effects of exogenous ethephon(Eth)on root characteristics,N uptake,dry matter distribution,and clarify the underlying relationship.Compared with YD6 and rcn1,SY63 and ZH11 had higher N accumulation,higher root aerenchyma area to cortex area ratio(ACR),higher NH_(4)^(+)uptake via the apoplasmic pathway and root-to-shoot NH_(4)^(+)translocation under no ethephon application(NEth)and Eth treatment,and elevated expression of the three genes(OsAMT1;2,OsAMT2;2,and OsAMT4;1)for ammonium transporters under Eth treatment.Eth treatment increased shoot N and dry matter accumulation,decreased the total root length and root diameter,and increased ACR and the expression of OsAMT genes in four genotypes.In summary,Eth could increase N accumulation via modifying root characteristics in rice,particularly by enlarging root aerenchyma and thinning the roots.The findings provide implications for development of elite rice varieties and green rice production with higher N efficiency.
基金supported by the National Natural Science Foundation of China(No.22073090,No.21991132,No.52021002)the National Key R&D Program of China(No.2020YFA0710700)the Funds of Youth Innovation Promotion Association,and the Fundamental Research Funds for the Central Universities(WK3450000009).
文摘CRISPR-based tran-scription regulators(CRISPR-TRs)have revolutionized the field of synthetic biol-ogy by enabling tar-geted activation or repression of any de-sired gene.However,the majority of exist-ing inducible CRISPR-TRs are limited by their dependence on specific sequences,which restricts their flex-ibility and controllability in genetic engineering applications.In this study,we proposed a novel strategy to construct sequence-independent inducible CRISPR-TRs,which is achieved by the design of stem loop 2 in the single guide RNA(sgRNA).Under this strategy,by utiliz-ing toehold-mediated strand displacement(TMSD)reactions between small endogenous molecules(miR-20a and TK1 mRNA)and bridge RNA(bRNA)to link bRNA with sgRNA,we achieved synergistic transcriptional activation of VP64 and p65-HSF1 in response to en-dogenous molecules.To enable response to exogenous molecules,we added response se-quences and bRNA sequences to the 5'end of sgRNA to block sgRNA activity,and achieved activation of sgRNA by shearing the response sequence,called sequential unlimited interlock-ing(SUI).Compared with conventional sequence-restricted interlocking(spacer-blocking hairpin(SBH)),the transcriptional activation ratio between response and non-response to the Cas6A protein using our approach was increased by 2.28-fold.Our work presents a modular and versatile framework for endogenous and exogenous molecule-responsive CRISPR-TRs in mammalian cells,without limitations imposed by sequence dependence.
基金Supported by Universities Discipline Innovation and Intellectual Introduction Program Funded Projects(B08025)Key Projects of Basic Scienceand Technology Platform of Ministry of Education(505005)Ministry ofAgriculture Project"948"(2006-G8(4)-31-1)~~
文摘[Objective] The research aimed to map QTL for the sensitivity of the traits related outcrosssing of Japonica rice to exogenous GA3 and provide theoretical basis for breeding and improving the high-sensitivity sterile line.[Method] Taking Japonica rice Xiushui 79 and C bao and their recombinant inbred line population 260 lines as test materials,the sensitivity of 4 traits related outcrossing to Exogenous GA3 and their QTL mapping were studied by using composite interval mapping..[Result]Three QTLs,which cont...
基金Supported by Post-graduate Innovation Program of Guangxi(YCSZ2013007)~~
文摘Objective The purpose of this experiment was to investigate the effects of exogenous hormone factors on subculture multiplication and root induction of tis-suecultured seedlings in mulberry. [Method] The aseptic seedlings of Guisangyou 12 were used as the materials and the comparative experiment on subculture multi-plication and root induction used different kinds,concentrations and combinations of exogenous hormones. [Result] The hormone combination of 0.1 mg/L IBA＋1.5 mg/L 6-BA＋0.03 mg/L TDZ showed the best effects to bud multiplication, and the multiple of bud multiplication was 5.28. The effects of NAA was better than IBA and IAA on root induction. The hormone combination of 2.0 mg/L NAA＋1.0 mg/L PP333 was most suitable to the root induction, in which the rooting rate arrived to 100%, the root number was 7.01 and the root length was 1.38 cm on average. [Conclusion] The results wil provide some technical reference for large-scale propagation of mul-berry seedlings in vitro.
基金This paper was supported by the National Natural Science Foundation of China (No. 39970627) and the Key Project of State Department of Science Technology (2002BA515B05).
文摘The content of total sugar, sucrose, fructose and protein in the leaves of3-yr.-old Betula platyphylla was measured after the treatment by three exogenous sugar solutions(sucrose, fructose, glucose) and three high concentrations of CO_2 (700, 1 400, 2 100 μL/L·L^(-1))for about a month in 1998. The results showed that spraying three exogenous sugar solutionsincreased markedly the content of sugar and protein of leaves under 700 μL·L^(-1) and 1 400μL·L^(-1) CO_2 The effect of spraying exogenous sucrose solution was the best among the threeexogenous sugars. The treatment of spraying exogenous sugar solution and 2 100 μL·L^(-1) CO_2constrained the accumulation of total sugar and protein of leaves. There was no difference inprotein content of leaves when spraying glucose and fructose solutions under 700 μL·L^(-1) and 1400 μL·L^(-1) CO_2. The treatment of 2 100 μL·L^(-1) CO_2 concentration significantly increasedthe contents of total sugar, sucrose, fructose, and protein of leaves compared with that of the 700μL·L^(-1) and 1 400 μL·L^(-1) CO_2 except the plants spraying fructose solution. There waspositive correlation between the content of sugar of leaves and CO_2 concentration when sprayingsame exogenous sugar solution.
基金Supported by Agricultral Science and Technology Development Program of Shanxi Pvince(20150311010-1)Agricultral Science and Technology Development Program of Datong City(201468-2,2015099)~~
文摘[Objective] This study was conducted to reveal the effect of exogenous calcium （Ca） in mitigating the damage caused by NaCI stress to watermelon seedlings. [Method] To the liquid medium containing 100 mmol/L NaCI, CaSO4 was added to the final concentrations of 4, 6, 10 and 14 mmol/L. The morphological and physiological indices including plant height, stem diameter, number of leaves per plant, maximum leaf length, maximum leaf width, seedling fresh weight and dry weight, malondialdehyde （MDA） content, relative permeability of plasma membrane, ascorbic acid （AsA） content, free proline content, soluble sugar content and soluble protein content in leaves of the seedlings treated with above media for 10 d were measured. [Result] NaCI stress significantly inhibited the growth of watermelon seedlings. The membrane permeability and MDA content in leaves were significantly increased under NaCI stress, and the contents of proline, soluble sugar, soluble protein and AsA were increased to different extents. Exogenous CaSO4 influenced the morphological and physiological indices of seedlings under NaCI stress in a manner. Treated with 6 mmol/L CaSO4, the growth of seedlings under salinity was significantly improved; membrane permeability and MDA content were drastically reduced, the contents of proline, soluble sugar, soluble pro- tein and AsA in leaves were significantly increased. [Conclusion] Exogenous CaSO＋ alleviates lipid peroxidation and inhibition of seedling growth under NaCI stress by improving the abilities of antioxidation and osmotic adjustment, and 6 mmol/L CaSO4 showed the best effect.
基金Supported by General Projects of Basic Research of Natural Sciencein Jiangsu Universities(KJD180118)Excellent Course Construction Project of Plant Physiology in Jiangsu Province(2010)+1 种基金Innovative Team Building and Personnel Training Programs in Zhejiang Science and Technology Department(2010F20007)Outstanding Teaching Team Project in Nanjing Xiaozhuang College(4085024)~~
文摘[Objective] The paper was to study the effects of exogenous GA3 on seed germination and seedling growth of Salicornia europaea L.under salt stress.[Method] With the combination of different concentrations of NaCl（50,100,150,200,250,300,350,400 mmol/L）with 10 μmol /L GA3 treatments,the effects of exogenous GA3 on seed germination and seedling growth of S.europaea under salt stress were studied.[Result] Exogenous GA3 promoted the seed germination rate,germination capacity,germination index and seed vigor index of S.europaea under salt stress.Under the treatment of exogenous GA3,the root system vigor,the lengths of roots and stems and the salt-tolerance of S.europaea were higher than that of single salt stress treatment.[Conclusion] Within a certain concentration range,exogenous GA3 could alleviate the inhibition effects of salt stress on seed germination and seedling growth of S.europaea.
文摘The mechanisms of sex determination and the influence of exogenous factors on sex differentiation in crustacean were reviewed in the paper.Most of crustecea have not obviously sex chromosome.Androgenic gland was reported as the most important sex differentiation factors,implanting or cuting AG can change the sexal characterization of larval in crustacean.Although sex differentiation of crustacean is determined by gene,it is affected by exogenous factors such as parasite,photoperiod,temperature or hormone.Most cultured species have different body weight and length between male and female,this can be used in aquaculture to produce all male or female crusteceans to improve the production.
基金Supported by Fund from Yunnan Academy of Tobacco Agricultural Sciences for Comparative Study of the Flue-cured Tobaccos of the New Tobacco-growing Areas in Yunnan Province and Those of Zimbabwe(09YN001)~~
文摘Objective] The aim of this study was to investigate the effects of exoge-nous amylases and Ca2＋, Mn2＋ and K＋ on the amylase specific activities and starch degradation of the upper leaves of ＇KRK26＇ planted in Yunnan Province during flue-curing. [Method] The amylase specific activities and starch degradation of the leaves were determined by using spectrophotometry. [Result] The 8 U/g exogenous α-amy-lase could improve the specific activity of the leaf α-amylase at yel owing and color-fixing stages, but could not at stem-drying stage, and similarly, the 80 U/g exoge-nous β-amylase could improved the specific activity of the leaf β-amylase at the yel owing stage and the early period of color-fixing stage. The leaf starch could be enhanced to degrade by the exogenous α- or β-amylases and the enhancing effect of the former was stronger than that of the later. 1.50 mg/ml Ca2＋ improved the specific activity of the leaf （α＋β）-amylase mainly due to its enhancing effect on the leaf α-amylase, and increased the starch degradation. 4 mmol/L Mn2＋ inhibited the leaf α-amylase from yel owing to the early period of color-fixing and the β- and （α＋β）-amylases from the yel owing to the later period of color-fixing, but enhanced the leafα-amylase from the later period of color-fixing to the later period of stem-drying and the β- and （α＋β）-amylases at the later period of stem-drying. Meanwhile, Mn2＋ ham-pered the starch degradation during yel owing, but promoted it from the early period of color-fixing to stem-drying. 1 mg/ml K＋ enhanced the leaf α-, β- and （α＋β）-amy-lases during the yel owing stage, but lowered them from the early period of color-fix-ing to the later period of stem-drying, and always inhibited the leaf starch degrada-tion. [Conclusion] The exogenous α-, β- amylases and Ca2＋ of suitable concentra-tions could be used to treat the tobacco leaves before flue-curing to improve the leaf starch degradation during the curing.
基金Supported by the Planning Subject of"the Twelfth Five-year-plan"in National Science and Technology for the Rural Development in China(2013BAD02B03-1-03-1)the China Agricultural Research System for Peach Industry(CARS-31-Z-2)+1 种基金the Key Technology R&D Program of Hebei Province(14226301D)the Special Financial Program of Hebei Province(494-0402-JBN-J42L)~~
文摘The effects of exogenous growth regulating substance on the fruit weight of peach were reviewed. Paclobutrazol could increase the single fruit weight in dif- ferent degree, and cytokinins could also increase the single fruit weight. GA3 and B9 had no effect on fruit size or on reducing single fruit weight. Chlorflurenol-methy, ABT and salicylic acid had no effect on fruit size. Suggestions on the future re- search were put forward.
基金supported by the National Natural Science Foundation of China (31601261, 31601252, 31571581 and 31571605)the China Postdoctoral Science Foundation (2016M592236)
文摘The growth and yield of peanut are negatively affected by continuous cropping.Arbuscular mycorrhizal fungi(AMF)and calcium ions(Ca^(2+))have been used to improve stress resistance in other plants,but little is known about their roles in peanut seedling growth under continuous cropping.This study investigated the possible roles of the AMF Glomus mosseae combined with exogenous Ca^(2+)in improving the physiological responses of peanut seedlings under continuous cropping.G.mosseae combined with exogenous Ca^(2+)can enhance plant biomass,Ca^(2+)level,and total chlorophyll content.Under exogenous Ca^(2+)application,the F_v/F_m in arbuscular mycorrhizal(AM)plant leaves was higher than that in the control plants when they were exposed to high irradiance levels.The peroxidase,superoxide dismutase,and catalase activities in AM plant leaves also reached their maximums,and accordingly,the malondialdehyde content was the lowest compared to other treatments.Additionally,root activity,and content of total phenolics and flavonoids were significantly increased in AM plant roots treated by Ca^(2+)compared to either G.mosseae inoculation or Ca^(2+)treatment alone.Transcription levels of AhCaM,AhCDPK,AhRAM1,and AhRAM2 were significantly improved in AM plant roots under exogenous Ca^(2+)treatment.This implied that exogenous Ca^(2+)might be involved in the regulation of G.mosseae colonization of peanut plants,and in turn,AM symbiosis might activate the Ca^(2+)signal transduction pathway.The combination of AMF and Ca^(2+)benefitted plant growth and development under continuous cropping,suggesting that it is a promising method to cope with the stress caused by continuous cropping.
基金supported by the National Key Research and Development Program of China(grant Nos.:2017YFD0301001 and 2016YFD0300403)the Shandong Province Mount Tai Industrial Talents Programthe National Natural Science Foundation of China(grant No.:31801295)。
文摘Drought at the grain filling stage of wheat will cause premature leaf senescence, thus leading to considerable loss of wheat yield. Therefore, this paper aims to establish a cultivation technology for strong drought resistance, delayed senescence, and yield improvement based on the analysis of hormones homeostasis obtained by applying chemical control substances. Experiments were conducted with two genotypes of wheat. Four water irrigation treatments were applied to impose the water deficit, including well-watered control treatment(WW), mild water deficit(MiWD), moderate water deficit(MoWD), and severe water deficit(SWD). Exogenous abscisic acid(ABA) was sprayed on the plants at the anthesis stage of the wheat. As a result, exogenous ABA reduced initial senescence rate(r0), total duration of chlorophyll(Chltotal), rapid senescence phase(Chlloss), and the accumulated temperature at an inflection point(M) but improved the persistence phase(Chlper) of flag leaves under all of the four treatments. However, exogenous ABA produced inconsistent effects on photoassimilate relocation and grain weight under different treatments. It produced positive regulatory effects on grain weight under WW, MiWD, and MoWD treatments. On the one hand, spraying ABA during the persistence phase of flag leaves reduced the ratios of zeatin to gibberellin(Z/GA3), spermine to spermidine(Spm/Spd), and salicylic acid to ABA(SA/ABA),which prolonged active photosynthesis by stimulating high level of proline(Pro) and increased the activities of antioxidant enzymes, such as superoxide dismutase(SOD), peroxidase(POD), catalase(CAT), and ascorbate peroxidase(APX). Therefore, drought tolerance was enhanced, and more photosynthetic assimilates were accumulated. On the other hand, the rapid senescence phase and the transport rate of assimilates into grains were accelerated, resulting in higher grain weight, yield, and water use efficiency(WUE). However, under SWD treatment, exogenous ABA improved the ratio of SA/ABA, leading to low Pro content and low antioxidant enzyme activity of flag leaves in the rapid loss phase. Meanwhile,drought resistance declined and the transport duration of assimilates into grains was shortened, thus making photosynthetic assimilates redundant. Therefore, exogenous ABA can lead to the reduction in grain weight, yield, and WUE of wheat under SWD treatment.
文摘Decreased expression of brain-derived neurotrophic factor（BDNF） plays an important role in the pathogenesis of Alzheimer＇s disease, and a typical pathological change in Alzheimer＇s disease is neurofibrillary tangles caused by hyperphosphorylation of tau. An in vivo model of Alzheimer＇s disease was developed by injecting okadaic acid（2 μL） and exogenous BDNF（2 μL） into the hippocampi of adult male Wister rats. Spatial learning and memory abilities were assessed using the Morris water maze. The expression levels of protein phosphatase 2 A（PP2 A）, PP2 Ac-Yp307, p-tau（Thr231）, and p-tau（Ser396/404） were detected by western blot assay. The expression levels of BDNF, TrkB, and synaptophysin mRNA were measured by quantitative real-time polymerase chain reaction. Our results indicated that BDNF expression was suppressed in the hippocampus of OA-treated rats, which resulted in learning and memory deficits. Intra-hippocampal injection of BDNF attenuated this OA-induced cognitive impairment. Finally, our findings indicated an involvement of the PI3 K/GSK-3β/AKT pathway in the mechanism of BDNF in regulating cognitive function. These results indicate that BDNF has beneficial effect on Alzheimer＇s disease, and highlight the potential of BDNF as a drug target for treatment of Alzheimer＇s disease.
基金The study was supported by grant of the research project of science and technology of the Provincial Higher Education Office, the Provincial Health Office and Li Ka-shing's endowment.
文摘Objective Nan'ao County in Guandong Province is a high-risk area of esophageal cancer in Southern China. Of the suspected etiological factors in the environment, N-nitrosamines and their precursors have received the greatest attention. Methods Sixty samples of the diet ingested by the inhabitants were collected and detected for volatile N-nitrosamines and their precursors. Five N-nitrosamines detected by Gas Chromatography-Thermal Energy Analyzer were N-nitrosodimethylamine, N-nitrosodiethylamine, N-nitrosopyrrolidine, N-nitrosopiperidine and N-nitrosomethyl-benzylamine. Results The average content of 5 volatile N-nitrosamines in the diet was 312.0 μg/kg (median). The daily intake of the nitrosamines was 286.5 μg/head/day. Only the ability to exogenously synthesize N-nitrosopiperidine was powerful among 5 volatile N-nitrosamines. By a computerized stepwise regression analysis and curve fitting, we studied the correlation among the nitrosamines, the precursors and the major food items in the samples. Conclusion It demonstrated that a relatively high content of volatile N-nitrosamines was present in the diet collected in the area.
文摘The aim of this study was to evaluate the effect of Lactobacillus acidophilus（LAC）, exogenous enzymes of ZAD（exogenous enzyme preparation） or their combination on feed conversion, and dressing of rabbits fed different treatments of sugarcane bagasse（SCB）. Five rations were allotted randomly to five groups of New-Zealand White（NZW） rabbits（n=10） with initial live body weight of（838±42.4） g and 5 weeks of age. Rabbits were fed on diets with different sources of fiber as follows,（i） a control diet composed of 100% berseem hay and 0% SCB,（ii） 50% berseem hay and 50% untreated SCB（USCB）,（iii） 50% berseem hay and 50% SCB treated with L. acidophilus（LAC）,（iv） 50% berseem hay and 50% SCB treated with ZAD（ZAD）, and（v） 50% berseem hay and 50% SCB treated with a combination of LAC＋ZAD（LZ）. Treatments of SCB with L. acidophilus, ZAD and LAC＋ZAD had the highest feed conversion ratio than both USCB and control. The dressing percentage of rabbits that fed the LAC and LZ diets was higher（P〈0.05） compared with that in the other groups. Performance index（PI） for LAC group was improved（P〈0.05） compared to that for the other groups; however, PI for USCB group was the lowest（P〈0.05）. It could be concluded that treating SCB with L. acidophilus, exogenous enzymes of ZAD or their combination improved feed conversion and performance with more positive effects with L. acidophilus than the other treatments.
基金the Key Program for International S&T Cooperation Projects of China(2022YFE0130100)Central Public-interest Scientific Institution Basal Research Fund of Chinese Academy of Agricultural Sciences(Y2022GH12).
文摘Background Sustainable strategies for enteric methane(CH_(4))mitigation of dairy cows have been extensively explored to improve production performance and alleviate environmental pressure.The present study aimed to investigate the effects of dietary xylooligosaccharides(XOS)and exogenous enzyme(EXE)supplementation on milk production,nutrient digestibility,enteric CH_(4) emissions,energy utilization efficiency of lactating Jersey dairy cows.Forty-eight lactating cows were randomly assigned to one of 4 treatments:(1)control diet(CON),(2)CON with 25 g/d XOS(XOS),(3)CON with 15 g/d EXE(EXE),and(4)CON with 25 g/d XOS and 15 g/d EXE(XOS+EXE).The 60-d experimental period consisted of a 14-d adaptation period and a 46-d sampling period.The enteric CO_(2)and CH_(4) emissions and O2 consumption were measured using two GreenFeed units,which were further used to determine the energy utilization efficiency of cows.Results Compared with CON,cows fed XOS,EXE or XOS+EXE significantly(P<0.05)increased milk yield,true protein and fat concentration,and energy-corrected milk yield(ECM)/DM intake,which could be reflected by the significant improvement(P<0.05)of dietary NDF and ADF digestibility.The results showed that dietary supplementation of XOS,EXE or XOS+EXE significantly(P<0.05)reduced CH_(4) emission,CH_(4)/milk yield,and CH_(4)/ECM.Furthermore,cows fed XOS demonstrated highest(P<0.05)metabolizable energy intake,milk energy output but lowest(P<0.05)of CH_(4) energy output and CH_(4) energy output as a proportion of gross energy intake compared with the remaining treatments.Conclusions Dietary supplementary of XOS,EXE or combination of XOS and EXE contributed to the improvement of lactation performance,nutrient digestibility,and energy utilization efficiency,as well as reduction of enteric CH_(4) emissions of lactating Jersey cows.This promising mitigation method may need further research to validate its long-term effect and mode of action for dairy cows.
