乙基亚硝基脲诱发转基因小鼠体内基因突变及微核形成

目的 用致突变剂乙基亚硝基脲（ＥＮＵ）验证基于ＰＵＣ１１８质粒的转基因小鼠用于体内诱变研究的可行性。方法 用酶切、环化方法从经过和未经过ＥＮＵ诱变处理的ｘｙｌＥ、Ｃ５７ＢＬ／６Ｊ基因小鼠脾脏组织ＤＮＡ中重新分离ｐＵＣ１１８ＮＸ质粒,使其转化ＤＨ１０Ｂ宿主菌并铺氨苄青霉素抗性平板培养后洒邻苯二酚溶液,通过菌落颜色不同筛选突变体,并对突变靶基因,ｘｙ／Ｅ测序分析以确定突变类型。同时取该转基因小鼠外周血     

Lycopene: An antioxidant and radioprotector against γ-radiation-induced cellular damages in cultured human lymphocytes

The present study aimed to evaluate the radioprotective effect of lycopene, a naturally occurring dietary carotenoid on γ-radiation-induced toxicity. The cellular changes were estimated by using lipid peroxidative indices like thiobarbituric acid reactive substances (TBARS), hydroperoxides (HP), the antioxidants superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and reduced glutathione (GSH). The DNA damage was analyzed by cytokinesis blocked micronucleus assay (CBMN), dicentric aberration (DC) and translocation frequency. The γ-radiation at different doses (1, 2 and 4 Gy) resulted in a significant increase in the number of micronuclei (MN), DC, translocation frequency, TBARS and HP level, whereas the levels of GSH and antioxidant enzymes were significantly decreased when compared with normal control. The maximum damage to lymphocytes was observed at 4 Gy irradiation. Lycopene pretreatment (1, 5 and 10 μg/ml) significantly decreased the frequency of MN, DC and translocation when compared with γ-radiation control. The levels of TBARS, HP were also decreased and activities of SOD, CAT and GPx were significantly increased along with GSH levels when compared with γ-radiation control. The dose of 5 μg/ml of lycopene was found to be more effective than the other two doses. Thus, our result shows that pretreatment with lycopene offers protection to normal lymphocytes against γ-radiation-induced cellular damage.     

Comparative study of β-carotene and microencapsulated β-carotene: Evaluation of their genotoxic and antigenotoxic effects

β-Carotene (BC) is one of the natural pigments that is most commonly added to food; however, the utilization of BC is limited due to its instability. Microencapsulation techniques are commonly used because they can protect the microencapsulated material from oxidization. Nevertheless, the properties of the encapsulated compounds must be studied. We compared the antigenotoxic potential of pure and microencapsulated β-carotene (mBC) in Wistar rats. Two doses of BC or mBC (2.5 or 5.0 mg/kg) were administered by gavage over a period of 14 days. The final gavage was followed by an injection of doxorubicin (DXR). After 24 h the animals were euthanized. The micronucleus test results showed that when both mBC and DXR were given, only the higher dose was antigenotoxic. The results of the comet assay show that when given in association with DXR, mBC had protective effects in the liver. The differences between the results obtained with BC and mBC suggest that possibly the carotenoid biodisponibility was modified by the process of microencapsulation. In conclusion, mBC does not lose its protective properties, but higher doses must be used to observe antigenotoxic effects. This is the first time that the genotoxicity and antigenotoxicity of a microencapsulated compound was evaluated in vivo.