Terahertz toroidal dipole metamaterial sensors for detection of aflatoxin B1

Terahertz metamaterial biosensors have attracted significant attention in the biological field due to their advantages of label-free,real-time and in situ detection.In this paper,a highly sensitive metamaterial sensor with semi-ring mirror symmetry based on toroidal dipole resonance is designed for a new metamaterial biosensor.It is shown that a refractive index sensitivity of 337.5 GHz per refractive index unit can be achieved under an analyte of saturated thickness near a 1.33 THz transmission dip.For biosensor samples where aflatoxin B1 is dropped on the metamaterial surface in our experiment,dip amplitudes of transmission varying from 0.1904 to 0.203 and 0.2093 are observed as aflatoxin B1 concentrations are altered from 0 to 0.001μg·ml-1 and to 0.01μg·ml-1,respectively.Furthermore,when aflatoxin B1 concentrations are 0.1μg·ml-1,1μg·ml-1,10μg·ml-1 and 100μg·ml-1,dip amplitudes of 0.2179,0.226,0.2384 and 0.2527 and dip redshifts of 10.1 GHz,20.1 GHz,27.7 GHz and 37.6 GHz are respectively observed.These results illustrate high-sensitivity,label-free detection of aflatoxin B1,enriching the applications of sensors in the terahertz domain.

Tissue inhibitor of metalloproteinase-3 expression affects clinicopathological features and prognosis of aflatoxin B1-related hepatocellular carcinoma

BACKGROUND The dysregulation of tissue inhibitor of metalloproteinase-3(TIMP3)was positively correlated with the progression of hepatocellular carcinoma(HCC).However,it is not clear whether TIMP3 expression is associated with the clinico-pathological features and prognosis of aflatoxin B1(AFB1)-related HCC(AHCC).A retrospective study,including 182 patients with AHCC,was conducted to explore the link between TIMP3 expression in cancerous tissues and the clinico-pathological characteristics and prognosis of AHCC.TIMP3 expression was detected by immunohistochemistry and its effects on the clinicopathological features and prognosis of AHCC were evaluated by Kaplan-Meier survival analysis and Cox regression survival analysis.Odds ratio,hazard ratio(HR),median overall survival time(MST),median tumor recurrence-free survival time(MRT),and corresponding 95%confidential interval(CI)was calculated to RESULTS Kaplan-Meier survival analysis showed that compared with high TIMP3 expression,low TIMP3 expression in tumor tissues significantly decreased the MST(36.00 mo vs 18.00 mo)and MRT(32.00 mo vs 16 mo)of patients with AHCC.Multivariate Cox regression survival analysis further proved that decreased expression of TIMP3 increased the risk of death(HR=2.85,95%CI:2.04-4.00)and tumor recurrence(HR=2.26,95%CI:1.57-3.26).Furthermore,decreased expression of TIMP3 protein in tissues with AHCC was significantly correlated with tumor clinicopatho-logical features,such as tumor size,tumor grade and stage,tumor microvessel density,and tumor blood invasion.Additionally,TIMP3 protein expression was also negatively associated with amount of AFB1-DNA adducts in tumor tissues.CONCLUSION These findings indicate that the dysregulation of TIMP3 expression is related to AHCC biological behaviors and affects tumor outcome,suggesting that TIMP3 may act as a prognostic biomarker for AHCC.

Surface-enhanced Raman Scattering of Aflatoxin B1 on Silver by DFT Method

The structure, electrostatic properties, and Raman spectra of aflatoxin B1 （AFB1） and AFB1-Ag complex are studied by density functional theory with B3LYP/6- 311G（d,p）/Lan12dz basis set. The results show that the surface-enhanced Raman scattering （SERS） and pre-resonance Raman spectra of AFB1-Ag complex strongly depend on the adsorption site and the excitation wavelength found to enhance 102-103 order compared to of the incident light. The SERS factors are normal Raman spectrum of AFB1 molecule due to the larger static polarizabilities of the AFB1-Ag complex, which directly results in the stronger chemical enhancement in SERS spectra. The pre-resonance Raman spectra of AFB1-Ag complex are explored at 266, 482, 785, and 1064 nm incident light wavelength, in which the enhancement factors are about 10^2-10^4, mainly caused by the charge-transfer excitation resonance. The vibrational modes are analyzed to explain the relationship between the vibrational direction and the enhanced Raman intensities.

量子点荧光微球免疫法定量检测小麦中黄曲霉毒素B1

目的建立量子点荧光微球免疫法快速检测小麦中黄曲霉毒素B1的方法。方法采用量子点荧光微球作为荧光标记物,与黄曲霉毒素B1的单克隆抗体偶联,构建量子点荧光微球探针。优化缓冲液pH、抗体最小标记量、荧光探针用量和包被抗原浓度等实验条件,建立检测卡上T线和C线信号峰值面积的比值与样本中黄曲霉毒素B1浓度的关系,构建定量标准曲线。针对小麦样品,将该检测方法与时间分辨荧光定量检测方法进行比较。结果本研究建立的荧光定量免疫层析检测方法最佳反应条件为:pH 7.5磷酸钠缓冲液,抗体标记量为20μg,荧光探针用量为4.0μL,抗原质量浓度使用0.40mg/mL。小麦中黄曲霉毒素B1的定量检测线性范围为0.05~25.00μg/kg,相关系数(r^(2))为0.9994,检出限为0.02μg/kg,定量限为0.05μg/kg。加标回收率为91.50%~115.00%,变异系数为1.88%~5.46%。结论本研究建立的荧光定量免疫层析方法快速、准确、稳定性好、可靠性高,适用于小麦中黄曲霉毒素B1的现场快速检测。

Protective Effect of Procyanidin B2 on Acute Liver Injury Induced by Aflatoxin B1 in Rats

Objective This study aimed to explore the protective effect of procyanidin B2(PCB2)on acute liver injury induced by aflatoxin B1(AFB1)in rats.Methods Forty Sprague Dawley rats were randomly divided into control,AFB1,AFB1+PCB2,and PCB2 groups.The latter two groups were administrated PCB2 intragastrically(30 mg/kg body weight)for 7 d,whereas the control and AFB1 groups were given the same dose of double distilled water intragastrically.On the sixth day of treatment,the AFB1 and AFB1+PCB2 groups were intraperitoneally injected with AFB1(2 mg/kg).The control and PCB2 groups were intraperitoneally administered the same dose of dimethyl sulfoxide(DMSO).On the eighth day,all rats were euthanized:serum and liver tissue were isolated for further examination.Hepatic histological features were assessed by hematoxylin and eosin-stained sections.Weight,organ coefficient(liver,spleen,and kidney),liver function(serum alanine aminotransferase,aspartate aminotransferase,alkaline phosphatase,total bilirubin,and direct bilirubin),oxidative index(catalase,glutathione,superoxide dismutase,malondialdehyde,and 8-hydroxy-2′-deoxyguanosine),inflammation factor[hepatic interleukin-6(IL-6)m RNA expression and serum IL-6],and bcl-2/bax ratio were measured.Results AFB1 significantly caused hepatic histopathological damage,abnormal liver function,oxidative stress,inflammation,and bcl-2/bax ratio reduction compared with DMSO-treated controls.Our results indicate that PCB2 treatment can partially reverse the adverse liver conditions induced by AFB1.Conclusion Our findings indicate that PCB2 exhibits a protective effect on acute liver injury induced by AFB1.

乳酸菌肽聚糖对雏鸭饲粮中黄曲霉毒素B 1的脱毒效果研究

本试验旨在探究乳酸菌肽聚糖对黄曲霉毒素B_(1)(AFB_(1))的吸附作用,为乳酸菌肽聚糖的制备和饲粮中AFB_(1)的脱毒提供科学依据及理论基础。试验以4种乳酸菌(嗜酸乳杆菌、嗜热链球菌、罗伊氏乳杆菌和植物乳杆菌)为原料提取乳酸菌肽聚糖,采用高效液相色谱法比较4种乳酸菌肽聚糖对AFB_(1)的体外吸附率,选取体外吸附效果最好的罗伊氏乳杆菌肽聚糖进行动物试验。选择1日龄健康樱桃谷鸭120只,随机分为5组,每组4个重复,每个重复6只。对照组饲喂基础饲粮,AFB_(1)组在基础饲粮中添加0.10 mg/kg AFB_(1),试验组在AFB_(1)组饲粮中分别添加0.10%(Ⅰ组)、0.15%(Ⅱ组)和0.20%(Ⅲ组)罗伊氏乳杆菌肽聚糖。预试期3 d,正试期21 d。结果表明:1)乳酸菌肽聚糖种类、添加量及二者的交互作用均能够显著影响AFB_(1)的体外吸附率(P<0.05),其中10.0 mg/mL罗伊氏乳杆菌肽聚糖对AFB_(1)的体外吸附率最高,达75.29%。2)与对照组相比,AFB_(1)组的平均日增重、平均日采食量显著降低(P<0.05),料重比显著升高(P<0.05);血浆谷草转氨酶(AST)、谷丙转氨酶(ALT)、碱性磷酸酶(AKP)活性及丙二醛(MDA)含量显著升高(P<0.05),肝脏、脾脏、胸腺和法氏囊指数显著升高(P<0.05),血浆免疫球蛋白G(IgG)、免疫球蛋白M(IgM)、γ-干扰素(IFN-γ)、白细胞介素-2(IL-2)、白细胞介素-4(IL-4)含量和超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)活性及总抗氧化能力(T-AOC)显著降低(P<0.05)。3)与AFB_(1)组相比,Ⅰ、Ⅱ、Ⅲ组的平均日增重显著升高(P<0.05),料重比显著降低(P<0.05);Ⅰ、Ⅱ、Ⅲ组的血浆IgG、IFN-γ、IL-2、IL-4含量和SOD、GSH-Px活性显著升高(P<0.05),血浆AST、AKP、ALT活性及MDA含量显著降低(P<0.05);Ⅱ、Ⅲ组的胸腺和法氏囊指数显著降低(P<0.05)。由此可见,不同乳酸菌肽聚糖对AFB_(1)体外吸附效果不同,饲粮中添加罗伊氏乳杆菌肽聚糖能够部分消除AFB_(1)对雏鸭造成的生长性能下降,改善AFB_(1)所导致的免疫功能降低以及肝脏毒性。

GSTM1 and XRCC3 Polymorphisms:Effects on Levels of Aflatoxin B1-DNA Adducts

Objective： Aflatoxin B1 （AFB1）, which can cause the formation of AFB1-DNA adducts, is a known human carcinogen. AFB1-exposure individuals with inherited susceptible carcinogen-metabolizing or repairing genotypes may experience an increased risk of genotoxicity. This study was designed to investigate whether the polymorphisms of two genes, the metabolic gene Glutathione S-transferase M1 （GSTM1） and DNA repair gene x-ray repair cross-complementing group 3 （XRCC3）, can affect the levels of AFB1-DNA adducts in Guangxi Population （n= 966） from an AFB1-exposure area. Methods： AFB1-DNA adducts were measured by ELISA, and GSTM1 and XRCC3 codon 241 genotypes were identified by PCR-RFLP. Results： The GSTM1-null genotype [adjusted odds ratio （OR） = 2.09; 95% confidence interval （CI） = 1.61-2.71] and XRCC3 genotypes with 241 Met alleles [i.e., XRCC3-TM and -MM, adjusted ORs （95% CI） were 1.43 （1.08-1.89） and 2.42 （1.13-5.22）, respectively] were significantly associated with higher levels of AFB1-DNA adducts. Compared with those individuals who did not express any putative risk genotypes as reference （OR = 1）, individuals featuring all of the putative risk genotypes did experience a significantly higher DNA-adduct levels （adjusted ORs were 2.87 for GSTM1-null and XRCC3-TM; 5.83 for GSTM1-null and XRCC3-MM）. Additionally, there was a positive joint effect between XRCC3 genotypes and long-term AFB1 exposure in the formation of AFB1-DNA adducts. Conclusion： These results suggest that individuals with susceptible genotypes GSTM1-null, XRCC3-TM, or XRCC3-MM may experience an increased risk of DNA damage elicited by AFB1 exposure.

Aflatoxin B1, zearalenone and deoxynivalenol in feed ingredients and complete feed from different Province in China

Background： The current study was carried out to provide a reference for monitory of aflatoxin B_1（AFB_1）,zearalenone（ZEN） and deoxynivalenol（DON） contamination in feed ingredients and complete feeds were collected from different Province in China from 2013 to 2015.Methods： A total of 443 feed ingredients, including 220 corn, 24 wheat, 24 domestic distillers dried grains with soluble（DDGS）, 55 bran, 20 wheat shorts and red dog, 37 imported DDGS, 34 corn germ meal and 29 soybean meal as well as 127 complete feeds including 25 pig complete feed（powder）, 90 pig complete feed（pellet）, six duck complete feed and six cattle complete feed were randomly collected from different Province in China,respectively, by high-performance chromatography in combined with UV or fluorescence analysis.Results： The incidence rates of AFB_1, ZEN and DON contamination of feed ingredients and complete feeds were80.8, 92.3 and 93.9 %, respectively. The percentage of positive samples for DON ranged from 66.7 to 100 %.Domestic DDGS and imported DDGS presented the most serious contamination AFB_1, ZEN and DON contamination levels of feeds ranged from 61.5 to 100 %, indicated that serious contamination over the studied 3-year period.Conclusion： The current data provide clear evidence that AFB_1, ZEN and DON contamination of feed ingredients and complete feeds in different Province in China is serious and differs over past 3-year. The use of corn, domestic DDGS, imported DDGS and corn germ meal, which may be contaminated with these three mycotoxins, as animal feed may triggered a health risk for animal. Feeds are most contaminated with DON followed by ZEN and AFB_1.Mycotoxins contamination in feed ingredients and complete feeds should be monitored routinely in China.

Isolation and Characterization of Recombinant Variable Domain of Heavy Chain Anti-idiotypic Antibodies Specific to Aflatoxin B_1

Some unique subclasses of Camelidae antibodies are devoid of the light chain, and the antigen binding site is comprised exclusively of the variable domain of the heavy chain （VHH）. The recombinant VHHs have a high potential as alternative reagents for the next generation of immunoassay. In particular, they might be very useful for molecular mimicry. The present study demonstrated an alpaca immunized with the F（ab＇）z fragment of anti-aflatoxin B1 mAb and developed an important anti-idiotypic （anti-ld） responses. Antigen-specific elution method was used for panning private anti-ld VHHs from the constructed alpaca VHH library. The selected VHHs were expressed, renatured, purified, and then identified by a competitive enzyme-linked immunosorbent assay （ELISA）. Our findings indicated that the VHH would be an alternative tool for haptens mimicry studies.

Effects of Ginkgo biloba extract on expression of biomarkers during aflatoxin B_1-induced hepatocarcinogenesis in Wistar rats

Objective： The aim of this study was to study the effect of Ginkgo biloba extract （EGb761） on metabolism of afiatoxin B1 （AFB1） in Wistar rats. Methods： Seventy one Wistar rats were assigned at random to groups A, B and C. Rats in groups A, B were injected with AFB1 （intraperitoneal, 100-200 ug/kg body weight, 1-3 times/week）. Group C was normal control. Rats in group B were fed in food with EGb761, while rats in groups A, C were given normal food. Blood samples were collected and liver biopsies were performed on the 14th, 28th and 42nd week. All the rats were sacrificed on the 64th week. The incidence of hepatocarcinoma was investigated. The hepatic phase I drug-metabolizing enzyme Cytochrome-P450 （CYP450） and phase II metabolizing enzyme glutathione S-transferase （GST） were analyzed with spectrometry. Serum AFB1- lysine adduct levels were assessed with high performance liquid chromatography （HPLC）. The expression of 8-hydroxydeoxy- guanosine （8-OHdG） was measured with immunohistochemistry. Results： The incidence of hepatocellular carcinoma （HCC） in group B was significantly lower than that in group A （26.92% vs 76.00%, P 〈 0.001）. No HCC developed in group C. EGb761 showed no effects on the activities of CYP450 and GST in rat liver tissues. The level of AFB1-lysine adduct reached the peak （4356.01 pg/mg albumin） at the 14th week in group A. EGb761 significantly inhibited the formation of AFB1-lysine adduct in serum by 13.07% at the 14th week （P = 0.033）, and 73.63% at the 42nd week （P = 0.002）. The expression of 8-OHdG protein in rat liver tissues in group B was significantly lower than that in group A at the 28th, 42nd, and 64th week （P 〈 0.05）. Conclusion： The main mechanism underlying the effect of EGb761 in blocking hepatocarcinogenesis induced by AFB1 may not be fully attributable to its influence on the activity of liver phase I and phase II metabolizing enzymes. EGb761 inhibits the production of AFB1-lysine adducts, decreases the expression of 8-OHdG protein, and finally alleviates the DNA oxidative injury, which may be one of the mechanisms for the effects of EGb761 in inhibiting or delaying AFB1-induced hepatocarcinogenesis.

Dietary aflatoxin B1 induces abnormal deposition of melanin in the corium layer of the chicken shank possibly via promoting the expression of melanin synthesis-related genes

San-Huang chicken is a high-quality breed in China with yellow feather, claw and break. However, the abnormal phenomenon of the yellow shank turning into green shank of San-Huang chicken has been a concern, as it seriously reduces the carcass quality and economic benefit of yellow-feathered broilers. In this study, the cause of this abnormal green skin in shank was systematically investigated. Physiological anatomy revealed that the abnormal skin in shank was primarily due to the deposition of melanin under the dermis. After analyzing multiple potential causes such as heredity(pedigree and genetic markers), environment(water quality monitoring) and feed composition(mycotoxin detection), excessive aflatoxin B1(AFB1) in feed was screened, accompanied with a higher L-dihydroxy-phenylalanine(L-DOPA)(P<0.05) and melanin content(P<0.01). So it was speculated that excessive AFB1 might be the main cause of abnormal green skin in shank. Subsequently, the further results showed that a high concentration of AFB1(>170 μg kg–1)indeed induced the abnormal green skin in shank compared to the normal AFB1 content(<10 μg kg–1), and the mRNA levels of TYR, TYRP1, MITE, MC1R and EDN3 genes related to melanin deposition would significantly up-regulate(P<0.01) and the content and activity of tyrosinase(TyR) significantly increased(P<0.05). At the same time, the content of L-DOPA and melanin deposition also increased significantly(P<0.01), which also confirmed the effect of excessive AFB1 on melanin deposition in skin of shank. Results of additional experiments revealed that the AFB1's negative effect on melanin deposition in skin of shank could last for a longer time. Taken together, the results of this study explained the occurrence and possible mechanisms of the abnormal AFB1-related green skin in shank of chickens. Excessive AFB1 in diets increased the L-DOPA content and melanin abnormal deposition in the chicken shank possibly via promoting TyR content and activity, and the expression of melanin synthesis-related genes. Furthermore, our findings once again raised the alarm of the danger of AFB1 in the broiler production.

A MOLECULAR EPIDEMIOLOGIC MARKER OF HEPATOCELLULAR CARCINOMA FROM AFLATOXIN B1 CONTAMINATED AREA IN THE SOUTHWEST OF GUANGXI

HCC specimens from high and low AFB1 risk areas in Guangxi showed different frequency of p53 mutational hot spot, which were 20/35 (57%) and 1/10 by DNA sequencing and 36/52 (69%) and 2/10 by RFLP analysis respectively. Their differences were significant (P<0.01). Mutational points of p53 gene induced by AFB1 mutagen almost exclusively clustered at codon 249 third nucleotide and by the form of G to T transversion only. We call it 'AFB1 mutational hot spot'. It turns out to be a significant marker for molecular epidemio logic survey to decide how many HCC and which individuals are induced by AFB1 mutagen, and if emergence of this marker in HCC is frequent in certain region it indicated that there is heavy contamination by AFB1.

Optimization of Extraction Process of Aflatoxin B_1 from Tartary Buckwheat Bran

In this study, the extraction process of aflatoxin B~ from tartary buckwheat bran was optimized with ELISA detection method to determine the optimal conditions for extracting aflatoxin B1 from tartary buckwheat bran. The results of standard recovery test of blank solvent and sample confirmed the feasibility of ELISA detection method. Orthogonal experiment was performed to optimize the solid-liquid ratio, ultrasonic extraction time and ultrasonic amplitude. The results show that it is feasible to detect aflatoxin B1 content with ELISA method. The optimal ultrasonic extraction conditions were ： methanol-water ratio 6： 4, solld-liquid ratio 1 g： 5 ml, ultrasonic extraction time 15 min, ultrasonic amplitude 15 ~. Under the optimized conditions, 1 065.1 ng/L aflatoxin B1 was extracted from tartary buckwheat bran.

Preparation of Immunomagnetic Beads Enrichment Kit for Detection of Aflatoxin B1

Immunomagnetic beads enrichment kit for detection of aflatoxin B1(AFB1) was prepared through reaction of AFB1 and p-phenylenediamine. The catches of AFB1 by the kit were 25 ng/mg. Furthermore, AFB1 was conducted specific reaction with competitive drugs with similar structure or function to AFB1, including aflatoxin M1, T-2 toxin, ochratoxin A, zearalenone and patulin, and no cross reaction was observed.

The Effects of Dietary Restriction and Aging on in Vivo and in Vitro Binding of Aflatoxin B_1 to Cellular DNA

Laboratory animals maintained on a reduced calorie but nutritionally adequate diet have extended life spans and lowered incidences of spontaneous and chemically induced cancers compared to ad libitum- fed counterparts. Many of the effects of dietary restriction on laboratory animals have been suggested to be related to a deceleration of the aging process. The inhibition of age-related changes in xenobiotic metabolizing enzyme activities by dietary restriction has previously been reported. Alterations of these enzyme activities may cause changes in metabolic activation of carcinogens and, therefore, carcinogen-DNA binding. DNA-repair capability has also been reported to be enhanced in diet-restricted rats. Using AFB1 as a model carcinogen, we have studied in vivo and in vitro hepatic AFB1 -DNA binding, demonstrating that dietary restriction (60% of ad libitum consumption) may decrease the metabolic activation of AFB1, and subsequently reduce AFB 1-DNA binding. Our preliminary results obtained from the AFB 1-DNA binding experiments in isolated hepatocytes suggest that the observed age-dependent reduction in AFB 1-DNA binding which may be attributed to a loss of metabolic activating capability was delayed in the diet-restricted rats.

An ultrasensitive time-resolved fluorescent immunoassay method for determination aflatoxins B1 in edible oil

Edible oil is one major nutritional ingredient to human and widely consumed directly. The contamination of aflatoxin B1 （AFB1） in edible oils has been attracted exten-sive efforts due to its hazard to human health and life. To avoid the digestion of edible oils contaminated by AFB1 the development of rapid and sensitive sensing method for AFB1 is required. Herein, a quantitative, sensitive and rapid method for AFB1 detection in edible oils was proposed by using ultrasensitive time-resolved fluorescent immunosensing （TRFIS） method. This method poses unique advantages from both time-resolved fluorescent sens-ing method and immunochromatographic assay format. The nanospheres were modified with fluorescent europium and then captured the home-made monoclonal antibody against AFB1 （3G1）. After optimization, by using a competitive immunosensing manner, this TRFIS method has a detectable linear range of 0.54-20.0 μg/kg with minimum detectable concen-tration of 0.18μg/kg. It can be completed merely within 10 min with recovery from 87.0% to 121.9%. The agreement was observed between the results by TRFIS and high perfor-mance liquid chromatography （HPLC） methods. This research provides a promising sens-ing method for sensitive and rapid determining AFB1 in edible oils.

黄曲霉毒素B1降解菌株的筛选及鉴定

【目的】筛选能降解黄曲霉毒素B1(AFB1)的细菌,以期在该毒素的生物脱毒中得到应用。【方法】以香豆素为惟一碳源和能源进行AFB1降解菌株的初筛,之后将初筛的10株菌分别降解浓度为100μg·kg-1的AFB1。【结果】筛选出的NMO-3菌株降解AFB1能力达85.7%,显著高于其它菌株(P<0.01)。从形态、生理生化反应以及16SrDNA序列比对等方面分析,最终确定NMO-3菌株为嗜麦芽窄食单胞菌(Stenotrophomonas sp.)。【结论】利用香豆素作为惟一碳源和能源筛选出了黄曲霉毒素降解菌株,后期试验证明活菌制剂在2.56×1010CFU/ml剂量以下不会引起急性毒性反应,用65%硫酸铵提取的蛋白(酶)具有AFB1降解能力。

一株黄曲霉毒素B_1降解菌的筛选及鉴定

以香豆素为唯一碳源进行AFB1降解菌的初筛,从青岛土壤中筛选出高效降解AFB1的菌株A6,分离该菌的上清液、菌悬液、胞内液并分析各组分降解AFB_1特征,通过形态学、生理生化和16S rRNA基因对该菌株进行鉴定。研究结果表明,菌株A6能高效降解AFB1,其胞外上清液、菌悬液和胞内液能分别降解90.6%、19.6%和12.8%的AFB_1,表明起降解的活性物质主要位于胞外液。在平板上该菌落呈现乳白色,具有皱褶,革兰氏染色呈阳性;能利用葡萄糖、阿拉伯糖、乳糖等碳源; 16S rRNA基因分析表明该菌与贝莱斯芽孢杆菌CR-502~T(Bacillus velezensis)相似度为99.64%。综合形态学特征、生理生化特征和16S rRNA基因分析结果,鉴定菌株A6为贝莱斯芽孢杆菌(Bacillus velezensis),命名为Bacillus velezensis A6。本研究结果为深入研究该菌的降解机理奠定了基础。

富硒麦芽对黄曲霉毒素B_1致肝肿瘤大鼠抗氧化作用及γ-GT酶活性的影响

刚断奶SD大鼠60只,体重50～60 g,随机均分成4组,每组雌性7只,雄性8只.在组Ⅰ(正常对照组)、组Ⅱ(试验对照组)和组Ⅲ(高亚硒酸钠组)的基础饲料中分别添加亚硒酸钠,使饲料硒含量分别为0.1、0.1和0.3 mg·kg-1;组Ⅳ(富硒麦芽组)在基础饲料中添加富硒麦芽,使硒含量达0.3 mg·kg-1.各组饲喂基础料,至体重增长到150～200 g(第32天)时,除组Ⅰ外,其余3组大鼠实施'黄曲霉毒素B1(aflatoxin B1,AFB1)致肝癌短期实验模型程序',并测定肝、肾组织和血中硒含量及谷胱甘肽过氧化物酶(GSH-Px)、超氧化物歧化酶(SOD)和γ-GT酶活性、丙二醛(MDA)和一氧化氮(NO)含量.实验结果显示:富硒麦芽较亚硒酸钠能更明显地提升全血和组织中GSH-Px活性,提高SOD水平,有效清除肾脏MDA,减少γ-GT灶.表明:富硒麦芽比亚硒酸钠能更有效地提高大鼠抗氧化能力,抑制肝细胞增生,从而抵抗AFB1所致肝肿瘤.

用cDNA微阵列技术研究HBV X基因与AFB_1对HBVx转基因小鼠药物代谢酶基因表达谱的影响

目的 研究乙型肝炎病毒X基因和黄曲霉毒素诱发小鼠肝癌过程中药物代谢酶基因表达谱的变化,探讨两因素协同致肝癌的机制。方法 用BiostarM 40s微阵列芯片比较研究HBVx组、AFB1 组和(AFB1+HBVx)组的肝组织基因表达谱与对照组的差异。结果 各实验组分别与对照组相比基因表达谱发生了明显的改变,各实验组上调与下调的基因数目分别为(AFB1+HBVx)组69项;AFB1 组101项;HBVx组35 项;其中与代谢酶相关的基因有18 项表达发生改变,分别为(AFB1 +HBVx)组13项(13/18,72%);HBVx组4项(4/18,22%);AFB1 组8项(8/18,44%)。结论 小鼠受到HBV X基因和AFB1双重攻击后,其体内的GST、EPHX和UDPGT等药物代谢酶基因表达水平明显低于HBVx组和AFB1 组。HBV与AFB1 协同致癌的分子机制很可能与两者引起药物代谢酶基因表达水平下调有关。