蒙脱石纳米复合物的制备及其吸附作用研究

对天然蒙脱石(M)矿物进行钠化改型和柱撑复合,制备了蒙脱石纳米复合物(MN),并对其进行表征,同时研究其对黄曲霉毒素的吸附作用。结果表明：与M相比,MN的层间距和比表面积明显增大,d₍₀₀₁₎值增加到1.96 nm,比表面积达到149.68m²/g,而且孔体积增加,孔直径缩小,微孔比例提高。吸附试验表明：复合改性后,MN对黄曲霉毒素的吸附容量和吸附速率均明显优于M。这些结果提示MN可望成为性能优越的黄曲霉毒素吸附剂。     

壳寡糖对黄曲霉毒素B1诱导大鼠肝细胞毒性损伤的干预作用

为了研究壳寡糖（COS）对黄曲霉毒素B1（AFB₁）诱导大鼠肝细胞（BRL 3A细胞）毒性损伤的干预作用。采用CCK-8法分别测定AFB₁对细胞的半数抑制浓度（IC₅₀）和COS对细胞的无损害作用浓度；用试剂盒检测COS预处理细胞6 h后再加入AFB₁继续培养24 h的细胞存活率、活性氧（ROS）水平、丙二醛（MDA）含量、超氧化物歧化酶（SOD）活性、谷胱甘肽S-转移酶（GST）活性和细胞凋亡率；通过Real-time quantitative PCR（RT-qPCR）测定Nrf2、Keap1、Ho-1、Nqo1、Bax和Bcl-2基因的mRNA相对表达量；最后通过RNA-seq研究分析差异表达基因的层次聚类和富集途径。结果：AFB₁对BRL 3A细胞的IC₅₀为15.86 μmol/L，COS浓度小于125 μmol/L时不会对细胞造成毒性损伤；COS可以缓解AFB₁引起的细胞内ROS水平和MDA含量升高，增强SOD和GST酶活性，进而提高细胞自身的抗氧化能力，降低细胞凋亡率；AFB₁可引起促凋亡基因Bax的显著表达（P<0.05），并显著降低Nrf2、Keap1、Ho-1、Nqo1的转录水平（P<0.05），而COS预处理则能显著提高Nrf2、Keap1、Ho-1、Nqo1基因的表达（P<0.05），显著降低Bax的表达水平（P<0.05）；在RNA-seq的富集途径结果中，COS还可能通过细胞色素P450对外源物质的代谢作用、药物代谢-细胞色素P450和p53信号通路途径来缓解AFB₁诱导的细胞毒性损伤（P<0.05）。结果表明：COS预处理对AFB₁诱导大鼠肝细胞的毒性损伤具有干预作用，其机制可能与Nrf2信号通路、细胞色素P450对外源物质的代谢作用、药物代谢-细胞色素P450和p53信号通路有关。     

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.     

黄曲霉毒素B1致病机制及防治研究进展

黄曲霉毒素(aflatoxins, AFs)是一类来自于霉菌中的剧毒物质, 其中以黄曲霉毒素B₁(aflatoxin B₁, AFB₁)的毒性最强、危害性最大。AFB₁是一种具有强致癌性及剧烈毒性的双呋喃环类毒素, 广泛分布于霉变的玉米、花生、大米和大豆等粮油作物中, 由AFB₁引发的人与动物中毒事件给当前食品安全和畜禽养殖等行业的发展造成了严重危害。AFB₁已被证明能够引起机体氧化应激、细胞凋亡、细胞焦亡、基因突变及免疫系统损伤。作者阐述了AFB₁抑制机体免疫系统、破坏机体免疫耐受性的免疫毒性作用; 介绍了AFB₁促进活性氧生成、激活Nrf2-ARE通路、诱导机体氧化应激和炎症反应进而造成器官损伤的器官毒性作用; 分析了AFB₁利用细胞死亡相关受体调控外源性细胞凋亡作用, 以及通过一系列细胞凋亡相关蛋白诱导内源性细胞凋亡作用, 还可利用肝细胞经典焦亡途径引发炎症反应, 继而引发非正常死亡的细胞毒性作用; 回顾了近年来关于AFB₁基因毒性与其去毒措施的作用机制及其研究进展。本综述有望为针对AFB₁致病机制的深入研究及相关防治药物的研发提供参考, 并为发霉粮油作物的去毒措施的选择提供有效依据。     

农产品及食品黄曲霉毒素污染研究

黄曲霉毒素主要由黄曲霉等产毒真菌产生，属生物源危害物，是毒性极强的一类真菌毒素，历史上因食用黄曲霉毒素污染产品造成过多次人及家养动物群体中毒死亡事件。黄曲霉毒素通过污染农产品与动物饲料进入食物链，严重威胁全球食品安全与人类健康。为了减少黄曲霉毒素污染危害，非常有必要掌握黄曲霉毒素污染农产品及食品主要种类。因此，本文通过研究国内外相关文献报道，较为全面地总结了近年来黄曲霉毒素污染农产品及其制品的主要种类，包括：谷物及其制品、调味品、饲料等12个类别，共计143种产品。通过归纳总结黄曲霉毒素污染产品种类，可以为农产品及食品黄曲霉毒素污染防治研究提供重要科学依据，对保障消费安全和产业健康发展具有重要指导意义。