纳米二氧化钛对果蝇肠道菌群影响的研究

发布时间：2018-03-12 13:26

  本文选题：纳米二氧化钛　切入点：果蝇　出处：《南京农业大学》2015年硕士论文　论文类型：学位论文

【摘要】：近年来,纳米科技的兴起与快速发展使得纳米材料被广泛应用于人们的日常生活中,目前纳米二氧化钛被认为对人体无毒性,已被应用于空气和水的净化,食品包装,防晒化妆品的生产等诸多方面。纳米二氧化钛的应用之广,使得它很容易随饮食、空气、水进入人体肠道,而人体肠道内共生着大量的肠道菌群,这些正常的共生菌群在宿主能量与代谢平衡中发挥着重要作用,一旦失调有可能影响宿主身体健康,导致疾病的产生。二氧化钛的光催化杀菌作用已被应用于实践,纳米二氧化钛一旦进入人体,在接触不到光照的情况下会对肠道菌产生怎样的作用,以及对人体造成怎样的毒副作用亟需研究。果蝇作为生物实验的模式生物,有着与哺乳动物相同的保守信号通路,且果蝇肠道共生菌种类数量较少,方便研究。实验室喂养的果蝇主要有5种共生菌,本实验主要针对其中的三种,醋酸菌,乳酸菌和肠杆菌来研究纳米二氧化钛对肠道菌的作用。通过分离出果蝇的三种肠道菌,在体外分别对其用10 nm,50 nm,100 nm二氧化钛处理,可以明显的看出高浓度(2 mg/ml)二氧化钛的杀菌作用,这与所报道的二氧化钛具有杀菌作用相吻合。已知的纳米二氧化钛杀菌机理是,纳米二氧化钛在吸收了一定波长的紫外光波后,其表面产生超氧化离子,超氧化离子作用于菌体致使菌体死亡,也有可能是纳米二氧化钛所具有的小尺寸效应,使其更容易穿透细胞膜,进入细胞体内,破坏细胞结构甚至遗传物质,最终致死菌体死亡。因为本实验在操作过程中是避光的,这就排除了光催化杀菌的作用,证明了在体外没有光催化的情况下,纳米二氧化钛也有杀菌作用。接下来,我们把实验转移到了果蝇体内,通过给果蝇幼虫和成虫喂食纳米二氧化钛,解剖肠道,统计三种菌的数量,体内实验得到的结果与体外实验明显不同,体内的结果显示与对照无明显差异,菌群数量没有受到影响。众所周知,菌群失衡能造成宿主身体病变,本实验中喂食纳米二氧化钛后没发现果蝇肠道菌受到影响,所以我们就推想果蝇身体状况应该也不会因为喂食纳米二氧化钛而有所改变。之后,我们的实验进一步看了喂食了纳米二氧化钛的幼虫和成虫的体重,生长发育情况,脂代谢及活力,希望通过这些果蝇身体指标直观的看一下纳米二氧化钛对机体的作用。与推测的一样,结果显示这些指标与对照相比并没有什么不同。本实验证明体内环境比体外更能保护肠道菌免受二氧化钛的毒害。关于纳米二氧化钛的毒性已经在小鼠中得到证实,一定浓度的纳米二氧化钛会造成小鼠肝脏,肺,大脑皮层等组织器官损伤。因为本实验只采取了两个浓度,实验所用果蝇也只喂食了5天的纳米二氧化钛,虽然没有对果蝇造成什么不利影响,但是却不能否认纳米二氧化钛的毒性作用,可能是实验中采用的二氧化钛浓度太低,使得其毒性没有发挥,也可能是因为作用时间太短,对宿主的影响作用还没有表现出来,所以只能说在低浓度和短时间内纳米二氧化钛不会影响肠道菌数量和宿主身体健康。至于加大纳米二氧化钛剂量和长期积累效应还有待进一步研究。
[Abstract]:In recent years, with the rise of the rapid development of nanotechnology makes nano materials have been widely used in people's daily life, the nano titanium dioxide is considered non-toxic to humans, purification, has been applied to air and water, food packaging, cosmetics production and many other aspects. Applications of nano titanium dioxide is wide, making it it's easy with food, air, water enters the human gut, and human gut symbiotic large intestinal flora, these normal symbiotic bacteria play an important role in host metabolism and energy balance, once the disorder may affect host health and cause disease. The photocatalytic bactericidal effect of titanium dioxide has been in practice, nano titanium dioxide once in the body, not in contact with sunlight will produce what kind of effect on the intestinal bacteria, and on the human body caused by the side effects of how to The research of Drosophila as a model organism. The biological experiment, a conserved signaling pathway and mammals, Drosophila and commensal bacteria number, to facilitate the study. Laboratory feeding flies mainly have 5 kinds of symbiotic bacteria, the experiment aimed at three, the acetic acid bacteria, lactic acid bacteria and Enterobacteriaceae to study nano the effect of titanium dioxide on intestinal bacteria. By separating three kinds of intestinal bacteria in Drosophila, in vitro were used on the 10 nm, 50 nm, 100 nm of titanium dioxide, can see the obviously high concentration (2 mg/ml) and the bactericidal effect of titanium dioxide, titanium dioxide has reported the bactericidal effect of nano titanium dioxide dicinfecting coincide. The mechanism is known, nano titanium dioxide absorbs certain wavelengths of ultraviolet light, superoxide ion on the surface, superoxide ions in bacteria resulting in the death of the cell, there may be satisfied The small size effect of titanium dioxide meter, making it easier to penetrate the cell membrane into the cell body, destroy the cellular structure and genetic material, and ultimately lethal bacterial death. Because of this experiment is to avoid light during operation, which precludes the photocatalytic bactericidal effect, proved in vitro without photocatalytic conditions next, nano titanium dioxide also has a bactericidal effect. Then, we put the transfer to the flies, the flies larvae and adults fed nano titanium dioxide, three kinds of intestinal anatomy, counting the number of bacteria, the in vivo experimental results in vitro and in vivo results show significantly different, no significant differences with control, flora the number is not affected. As everyone knows, flora imbalance can cause the host body disease, found no feeding of nano titanium dioxide in this experiment of Drosophila intestinal flora is affected, so we suppose Drosophila health should not be changed because the feeding of nano titanium dioxide. After that, we further see fed nano-TiO2 larvae and adult body weight, growth, lipid metabolism and vitality, hope to watch the effect of nanometer titanium dioxide on the body look through these Drosophila body index intuitive. Like that, the results show that these indexes compared with the control was not different. What this experiment demonstrated that the in vivo environment can protect the intestinal bacteria than in vitro from titanium dioxide poisoning. On the toxicity of nano titanium dioxide has been confirmed in mice, a certain concentration of nano titanium dioxide will cause the liver, lung, brain and other organ damage. Because of this experiment only take the two concentration of the Drosophila feeding only 5 days of nano titanium dioxide, although not on the fly by 浠，

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