排序方式: 共有4条查询结果,搜索用时 31 毫秒
1
1.
Antioxidative capacity and enzyme activity in Haematococcus pluvialis cells exposed to superoxide free radicals 总被引:1,自引:1,他引:0
The antioxidative capacity of astaxanthin and enzyme activity of reactive oxygen eliminating enzymes such as superoxide dismutase
(SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) were studied in three cell types of Haematococcus pluvialis exposed to high concentrations of a superoxide anion radical (O2−). The results show that defensive enzymes and astaxanthin-related mechanisms were both active in H. pluvialis during exposure to reactive oxygen species (ROS) such as O2−. Astaxanthin reacted with ROS much faster than did the protective enzymes, and had the strongest antioxidative capacity to
protect against lipid peroxidation. The defensive mechanisms varied significantly between the three cell types and were related
to the level of astaxanthin that had accumulated in those cells. Astaxanthin-enriched red cells had the strongest antioxidative
capacity, followed by brown cells, and astaxanthin-deficient green cells. Although there was no significant increase in expression
of protective enzymes, the malondialdehyde (MDA) content in red cells was sustained at a low level because of the antioxidative
effect of astaxanthin, which quenched O2− before the protective enzymes could act. In green cells, astaxanthin is very low or absent; therefore, scavenging of ROS
is inevitably reliant on antioxidative enzymes. Accordingly, in green cells, these enzymes play the leading role in scavenging
ROS, and the expression of these enzymes is rapidly increased to reduce excessive ROS. However, because ROS were constantly
increased in this study, the enhance enzyme activity in the green cells was not able to repair the ROS damage, leading to
elevated MDA content. Of the four defensive enzymes measured in astaxanthin-deficient green cells, SOD eliminates O2−, POD eliminates H2O2, which is a by-product of SOD activity, and APX and CAT are then initiated to scavenge excessive ROS. 相似文献
2.
目前中国妇女乳腺癌的发病率呈逐年上升趋势,据报已居女性恶性肿瘤的首位。尤其是患 乳癌的年轻妇女逐年上升,应引起诊断医生和社会的重视。早期癌症的发现对其治疗和预后的重要意义。作者自1983年以来,为以乳腺病就诊断的患者行X线摄影9183例,并与有关胸部乳腺CT片相对比,总结其中资料完整均手术病理证实的乳腺518例,(包括2例男性乳癌)进行影像学和临床方面的分析。 相似文献
3.
Two strains H2-410 and H2-419 were obtained from the chemically mutated survivors of wild Haematococcus pluvialis 2 by using ethyl methanesulphonate (EMS). Strains H2-410 and H2-419 showed a fast cell growth with 13% and 20% increase in biomass compared to wild type, respectively. Then H2-419-4, a fast cell growth and high astaxanthin accumulation strain, was obtained by exposing the strain H2-419 to ultraviolet radiation (UV) further. The total biomass, the astaxanthin content per cell, astaxanthin production of H2-419-4 showed 68%, 28%, and 120% increase compared to wild H. pluvialis 2, respectively. HPLC (High Performance Liquid Chromatography) data showed also an obvious proportional variation of different carotenoid compositions in the extracts of H2-419-4 and the wild type, although no peak of carotenoids appeared or disappeared. Therefore, the main compositions in strain H2-419-4, like its wild one, were free of astaxanthin, monoester, and diester of astaxanthin. The asexual reproduction in survivors after exposed to UV was not synchronous, and different from the normal synchronous asexual reproduction as the mother cells were motile instead of non-motile. Interestingly, some survivors from UV irradiation produced many mini-spores (or gamete?), the spores moved away from the mother cell gradually 4 or 5 days later. This is quite similar to sexual reproduction described by Elliot in 1934. However, whether this was sexual reproduction remains questionable, as no mating process has been observed. 相似文献
4.
The antioxidative capacity of astaxanthin and enzyme activity of reactive oxygen eliminating enzymes such as superoxide dismutase (SOD),peroxidase (POD),catalase (CAT) and ascorbate peroxidase (APX) were studied in three cell types of Haematococcus pluvialis exposed to high concentrations of a superoxide anion radical (O2ˉ).The results show that defensive enzymes and astaxanthin-related mechanisms were both active in H.pluvialis during exposure to reactive oxygen species (ROS) such as Oˉ2.Astaxanthin reacte... 相似文献
1