本文選題：甲醛　切入點：甲醛脫氫酶　出處：《華中師范大學》2013年碩士論文　論文類型：學位論文

【摘要】：甲醛是一種常見的室內(nèi)空氣污染物,甲醛污染具有來源廣,毒性大,污染時間長,毒性機理不明確等特點。甲醛化學性質(zhì)活潑,能與脂類,蛋白質(zhì),核酸共價交聯(lián)反應,甲醛也是生物內(nèi)源性的代謝產(chǎn)物,各種RNA和DNA脫甲基化反應都能產(chǎn)生低濃度的甲醛。 2004年國際癌癥研究所(IARC)將甲醛確立人類致癌物,它可引起人類鼻咽癌,但是對于甲醛會導致白血病,世界衛(wèi)生組織認為存在有力的流行病學證據(jù)但分子生物學的證據(jù)不夠充分,需要進一步研究證明。本文旨在從分子生物學的角度研究甲醛在細胞內(nèi)的代謝途徑及其毒性機制。 為研究甲醛暴露對離體細胞毒性的影響是否由其自身基團造成,實驗選用了不同濃度的甲醛及其衍生物甲醇、甲酸以及醛基的同類物乙醛四種物質(zhì)對離體培養(yǎng)Hela細胞進行染毒處理,測定細胞的氧化損傷水平以及細胞內(nèi)甲醛含量以及甲醛脫氫酶表達量變化。實驗結果發(fā)現(xiàn),染毒1小時后,低濃度的甲醛(10μmol/L)對細胞的生長具有促進作用,高濃度甲醛(62.5μmol/L濃度及以上)抑制細胞的生長,在125μmol/L濃度下四種化學物均影響細胞生長,其中甲醛對細胞活性影響最大。甲醛、甲酸、甲醇、乙醛四種物質(zhì)暴露,對于離體培養(yǎng)細胞均能產(chǎn)生氧化損傷且影響細胞內(nèi)源性甲醛含量,引起細胞內(nèi)甲醛含量升高,并誘導細胞內(nèi)甲醛脫氫酶的表達上調(diào),各組甲醛脫氫酶的表達量分別是空白組為1,甲醇組10.6,甲醛組10.4,甲酸組0.9,乙醛組1.1,其中,甲醛和甲醇染毒后,甲醛脫氫酶的表達量與空白組有顯著差異。實驗結果表明,外界甲醛可以通過細胞膜進入細胞,短時間內(nèi)能影響細胞內(nèi)的甲醛含量,且能誘導細胞內(nèi)甲醛脫氫酶高效表達,使進入細胞內(nèi)甲醛被降解,在24h修復后,甲醛恢復到本底濃度,細胞內(nèi)甲醛的含量處于一個穩(wěn)定的水平。甲醛的毒性不僅僅是其中的碳原子,羥基,或羧基基團的降解產(chǎn)生氧化損傷,其毒性可能通過其它機制發(fā)生,甲醛可能作為一種的信號分子,在細胞生長過程中起著重要的生物學作用。
[Abstract]:Formaldehyde is a common indoor air pollutant. Formaldehyde pollution has many characteristics, such as wide source, high toxicity, long time of pollution, unclear toxic mechanism, etc. Formaldehyde is chemically active and can be cross-linked with lipids, proteins and nucleic acids. Formaldehyde is also a biological endogenous metabolite. All kinds of RNA and DNA demethylation reactions can produce low concentration of formaldehyde. In 2004, the International Cancer Institute (IARC) established formaldehyde as a human carcinogen, which can cause human nasopharyngeal carcinoma, but the WHO believes that there is strong epidemiological evidence but not enough molecular biological evidence for formaldehyde to lead to leukemia. The aim of this paper is to study the metabolic pathway of formaldehyde in cells and its toxic mechanism from the point of view of molecular biology. In order to study whether the effect of formaldehyde exposure on in vitro cytotoxicity was caused by its own groups, different concentrations of formaldehyde and its derivative methanol were used in the experiment. In vitro Hela cells were treated with formic acid and aldehyde. The levels of oxidative damage, the content of formaldehyde and the expression of formaldehyde dehydrogenase were measured. One hour after exposure, 10 渭 mol 路L ~ (-1) of formaldehyde at a low concentration could promote the growth of the cells, and a high concentration of 62.5 渭 mol/L and above) inhibited the growth of the cells. At the concentration of 125 渭 mol/L, all the four chemicals affected the growth of the cells. Formaldehyde has the greatest effect on cell activity. Exposure to formaldehyde, formic acid, methanol and acetaldehyde can cause oxidative damage and increase the content of intracellular formaldehyde in cultured cells. The expression of formaldehyde dehydrogenase was up-regulated in the cells. The expression of formaldehyde dehydrogenase was 1 in blank group, 10.6 in methanol group, 10.4 in formaldehyde group, 0.9 in formic acid group and 1.1 in acetaldehyde group. The results showed that formaldehyde could enter the cells through the cell membrane, affect the formaldehyde content in the cells in a short time, and induce the high expression of formaldehyde dehydrogenase in the cells. After 24 hours of repair, formaldehyde is restored to its background concentration, and the content of formaldehyde in cells is at a stable level. The toxicity of formaldehyde is not just carbon atoms, hydroxyl groups, The degradation of carboxyl groups may cause oxidative damage, and its toxicity may occur through other mechanisms. Formaldehyde, as a signaling molecule, may play an important biological role in the process of cell growth.
【學位授予單位】：華中師范大學
【學位級別】：碩士
【學位授予年份】：2013
【分類號】：R114

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