R-藻红蛋白介导的光敏反应对DNA分子的生物学效应

藻红蛋白(phycoerythrin, PE)是海藻中的重要捕光色素蛋白,具有强荧光性,易溶于水.在藻体内能将捕获的光能传递给光合反应中心; 在体外则能将光能传递给周围环境中的氧分子,产生如单线态氧等活性氧组分,可用来介导光动力效应治疗癌症.将纯化的藻红蛋白加入到瘤细胞培养基中,数小时后,采用488 nm波长的氩离子激光辐照,MTT法检测细胞存活数,计算细胞存活率. ³H-TdR掺入实验观察细胞DNA的合成.结果表明,藻红蛋白介导的光动力反应能够有效地抑制肿瘤细胞DNA合成并杀伤癌细胞.随着藻红蛋白浓度增加,DNA合成下降,瘤细胞存活率降低.将藻红蛋白加入到pUC18质粒溶液中,随之进行激光辐照,琼脂糖电泳结果可见pUC18构象由超螺旋（supercoiled）向带切口的环形构象(relax)转换.结果提示：通过改变或影响DNA构象,抑制细胞DNA合成可能是藻红蛋白介导肿瘤光动力治疗的途径之一.     

两种藻胆蛋白对人喉癌Hep-2细胞的光动力杀伤效果

从条斑紫菜中提取高纯度R-藻红蛋白(R-PE)和R-藻蓝蛋白(c-pc),采用MTT法测定主要研究了不同浓度(10、25、50和100μg/ml)R-PE和C-PC分别介导的光动力效应对人喉癌Hep-2细胞的生存率的影响.实验结果显示,两种藻胆蛋白的光动力作用对Hep-2细胞具有杀伤作用.在浓度为100μg/ml,照射剂量为5OJ/cm2的条件下,藻蓝蛋白对应的细胞存活率为64%.藻红蛋白对应的仅为57%;单用碘钨灯处理,Hep-2细胞的存活率达到86.9%;而单独使用这两种藻胆蛋白处理Hep-2细胞,培养24h后,低浓度藻胆蛋白(10、25μg/ml)对细胞的抑制效果不明显,高浓度对细胞生长具有一定的抑制效果,抑制率为68%.实验证明条斑紫菜R-藻红蛋白和C-藻蓝蛋白具有可开发人喉癌治疗光敏剂应用前景.     

Fe^3＋对雨生红球藻（Haematococcus pluvialis）生长及荧光特性的影响

为探求适宜雨生红球藻CG-06株生长的Fe^3＋浓度和Fe^3＋对藻细胞荧光特性的影响,以BBM为基础培养基,选用EDTA—FeNa（Ⅲ）为Fe^3＋源,设置0、1．79、8．95、17．9、35．8、71．6μmol·L^-1 6种Fe^3＋浓度梯度,实验测定藻的生长并分析不同Fe^3＋对藻细胞叶绿素荧光和77K低温荧光等的影响。结果表明：适合雨生红球藻CG-06株生长的Fe^3＋浓度为8．95μmol·L^-1,Fe^3＋浓度较高时,雨生红球藻的生长受到抑制,Fe^3＋浓度低于1．79μmol·L^-1将产生低铁限制。Walz—PAM测定数据显示,在铁不足或高铁抑制条件下,雨生红球藻光系统Ⅱ活性明显下降,开放态的反应中心数目减少,光合作用受到抑制。77K低温荧光光谱显示,在铁不足或高铁抑制条件下,710nm荧光峰降低,684nm和694nm荧光峰相对增强,说明能量在两个光系统分配上发生变化,能量更多的分配给光系统Ⅱ,限制了光系统Ⅰ的活性。在高铁抑制条件下,CP47蛋白荧光峰降低,CP43蛋白荧光峰增强,推测存在D1蛋白降解。     

Fe3+对雨生红球藻(Haematococcus pluvialis)生长及荧光特性的影响

为探求适宜雨生红球藻CG-06株生长的Fe³⁺浓度和Fe³⁺对藻细胞荧光特性的影响,以BBM为基础培养基,选用EDTA-FeNa(Ⅲ)为Fe³⁺源,设置0、1.79、8.95、17.9、35.8、71.6μmol·L^-16种Fe³⁺浓度梯度,实验测定藻的生长并分析不同Fe³⁺对藻细胞叶绿素荧光和77 K低温荧光等的影响。结果表明:适合雨生红球藻CG-06株生长的Fe³⁺浓度为8.95μmol·L^-1,Fe³⁺浓度较高时,雨生红球藻的生长受到抑制,Fe³⁺浓度低于1·79μmol.L^-1将产生低铁限制。W alz-PAM测定数据显示,在铁不足或高铁抑制条件下,雨生红球藻光系统Ⅱ活性明显下降,开放态的反应中心数目减少,光合作用受到抑制。77 K低温荧光光谱显示,在铁不足或高铁抑制条件下,710 nm荧光峰降低,684 nm和694 nm荧光峰相对增强,说明能量在两个光系统分配上发生变化,能量更多的分配给光系统Ⅱ,限制了光系统Ⅰ的活性。在高铁抑制条件下,CP₄₇蛋白荧光峰降低,CP₄₃蛋白荧光峰增强,推测存在D₁蛋白降解。     

Pheophorbide a在脂质体介质中的光敏反应特性

Pheophorbidea(PPa)———叶绿素a的一种分解产物 ,是一种光敏剂 .用自旋捕捉和消自旋等ESR技术及激光光解技术研究了PPa在PBS和DPPC脂质体介质中光敏反应的Ⅰ型和Ⅱ型机制 .通过比较发现 ,DPPC脂质体的加入显著增强了PPa光敏反应产生PPa ^- (Ⅰ型 )和¹O₂ (Ⅱ型 )的能力 .这种增强反应源于脂质体对PBS中的PPa聚集态的解聚作用和它对PPa三重激发态的保护作用 .这表明 ,PPa在非均相脂质体体系中的光敏反应有别于均相水体系 ,而表现出更高的光敏效率 .此结果对解释属于非均相生物体系的肿瘤的光动力治疗机理有重要意义 .     

R─藻红蛋白三维结构研究

藻类的捕光系统是由棒状的藻胆体构成的,藻胆体又是由藻红蛋白、藻蓝蛋白和变藻蓝蛋白组成的。光能从藻红蛋白传递到藻蓝蛋白,再传递到变藻蓝蛋白,最后传递到光反应中心,其传递效率接近100％。R─藻红蛋白是藻红蛋白的一种;它是多亚基,超大分子量的蛋白色素复合物。为了阐明光能传递的机理,我们使用X─射线晶体学的方法,对取自多管藻的R─藻红蛋白的三维结构进行了长期的研究并取得了一系列进展。首先,我们使用多对同晶置换法获得了R─藻红蛋白5A分辨率的结构,随后经过努力又获得了R─藻红蛋白2．8A中分辨率和1．9A高分辨率的结构,并首次解析了藻尿胆素的三维结构。我们通过对R─藻红蛋白三维结构的详细分析,对光能传递中的一些重要问题提出了自己的看法。该结构为我国有关藻类捕光蛋白的系列研究和光合作用机制研究打下了非常重要的基础。     

转基因鱼腥藻中hTNF-α基因表达与光合作用间的相关性研究

分析了培养光强对转基因鱼腥藻生长和hTNF-α基因表达的影响,以及转基因鱼腥藻IB02的光合放氧活性、光系统Ⅰ及光系统Ⅱ活性。发现光强对转基因鱼腥藻IB02的生长和hTNF-α基因表达都有促进;hTNF-α基因在鱼腥藻中的表达率与真正光合、光系统Ⅰ和光系统Ⅱ活性存在一定的联系。hTNF-α基因表达同时对宿主的光合放氧特性也产生了显著的影响,与正对照相比转基因藻光呼吸速率增强68%,饱和点降低66%,说明转基因鱼腥藻的代谢负荷增加,并在低光强下生长比野生型快。     

藻蓝蛋白亚基脂质体光动力学抗乳腺癌细胞的实验研究

目的:研究PEG修饰的藻蓝蛋白亚基光敏剂长循环脂质体介导的光动力疗法抗乳腺癌的效果.方法:采用薄膜水合-超声分散法制备PEG修饰的藻蓝蛋白亚基脂质体(PEG-PCS-lip),MTT法检测藻蓝蛋白亚基脂质体对MCF-7(人乳腺癌细胞)、MA-782(鼠乳腺癌细胞)的光动力杀伤效果,流式细胞术(FCM)分析其对肿瘤细胞周期的影响,并对乳腺癌模型鼠做PDT治疗.结果:PEG-PCS-lip介导的PDT作用对乳腺癌细胞有良好的光动力疗效,对MCF-7及MA-782细胞IC_(50)(半数抑制浓度)分别为68 μg/mL、70 μg/mL;FCM的结果显示,当PEG-PCS-lip 浓度为50 μg/mL时,MCF-7凋亡率约为30.5 %; 用10 mg/kg PEG-PCS-lip静脉注射荷瘤小鼠,光照剂量为208.2 J/cm~2时,其抑瘤率可达到72 %;组织切片观察PDT作用后的肿瘤组织,瘤体中间以细胞凋亡为主,瘤体外周以细胞坏死为主,由血管损伤而形成的空腔增多.结论:PEG-PCS-lip在体外对乳腺癌细胞有良好的光动力杀伤效果,肿瘤细胞凋亡及瘤血管破坏是导致肿瘤细胞死亡的主要原因.     

链格孢菌毒素对莱茵藻光系统Ⅱ的多重影响

链格孢菌毒素是从杂草紫茎泽兰中分离的天然致病真菌产生的植物毒素。以莱茵藻为实验材料,采用氧电极法和快速叶绿素荧光诱导动力学方法,研究链格孢菌毒素的作用位点。结果表明,该毒素对莱茵藻光系统Ⅱ有多重影响:(1)阻断受体侧QA到QB的电子传递;(2)使反应中心失活;(3)降低光能转化效率;(4)破坏(或迁移)反应中心的部分天线色素;(5)降低活性与非活性反应中心的天线色素之间能量传递的协调性。研究证实链格孢菌毒素在莱茵藻光系统Ⅱ中存在多个作用位点。     

R-藻红蛋白的结构、功能及其应用

R-藻红蛋白是最重要类型的藻红蛋白,为许多藻类的前级捕光色素蛋白,在光的激发下,能发出桔红色荧光。现对R-藻红蛋白的三维结构与功能的关系、R-藻红蛋白离体的光学活性在肿瘤光动力学治疗(PDT)中作为光敏剂和荧光免疫检测等领域作为荧光探针分子的应用进行综述。     

Photosensitized formation of singlet oxygen by phycobiliproteins in neutral aqueous solutions

Phycobiliproteins (PBPs) are a type of promising sensitizers for photodynamic therapy (PDT). Upon irradiation (lambda>500nm) of an oxygen-saturated aqueous solution of phycobiliproteins, particularly, C-phycocyanin (C-PC), allophycocyanin (APC) or R-phycoerythrin (R-PE), the formation of singlet oxygen (1O2) was detected by using imidazole in the presence of p-nitrosodimethylaniline (RNO). The bleaching of RNO caused by the presence of imidazole in our system showed typical concentration dependence with a maximum at about 8mM imidazole, which is in agreement with the formation of 1O2. In addition, the generation of 1O2 was verified further in the presence of D2O and specific singlet oxygen quencher 1,4-diazabicyclo [2,2,2] octane (DABCO) and sodium azide (NaN3). Our experimental results indicated that APC possesses high ability to generate reactive oxygen species and the relative quantum yields of photogeneration of 1O2 by PBPs are as follows: APC > C-PC > R-PE.     

Photosensitized formation of singlet oxygen by phycobiliproteins in neutral aqueous solutions

Phycobiliproteins (PBPs) are a type of promising sensitizers for photodynamic therapy (PDT). Upon irradiation (λ>500nm) of an oxygen-saturated aqueous solution of phycobiliproteins, particularly, C-phycocyanin (C-PC), allophycocyanin (APC) or R-phycoerythrin (R-PE), the formation of singlet oxygen (¹O₂) was detected by using imidazole in the presence of p-nitrosodimethylaniline (RNO). The bleaching of RNO caused by the presence of imidazole in our system showed typical concentration dependence with a maximum at about 8mM imidazole, which is in agreement with the formation of ¹O₂. In addition, the generation of ¹O₂ was verified further in the presence of D₂O and specific singlet oxygen quencher — 1,4-diazabicyclo [2,2,2] octane (DABCO) and sodium azide (NaN₃). Our experimental results indicated that APC possesses high ability to generate reactive oxygen species and the relative quantum yields of photogeneration of ¹O₂ by PBPs are as follows: APC > C-PC > R-PE.     

Toward a molecular understanding of the photosensitizer–copper interaction for tumor destruction

The aim of this study was to shown that the photosensitizer in photodynamic therapy (PDT) can contribute to the dark toxicity and phototoxicity of the tumor by binding with copper. This binding process can remove the copper from the body, stopping angiogenesis as well as activating the mechanisms of cell death, such as apoptosis and necrosis. In PDT, this coupling may be considered a new route for fighting cancer in addition to those already known which involve reactive oxygen species.     

Regulatory pathways in photodynamic therapy induced apoptosis.

Photodynamic therapy is an approved treatment for several types of tumors and certain benign diseases, based on the use of a light-absorbing compound (photosensitizer) and light irradiation. In the presence of molecular oxygen, light-activation of the photosensitizer, which accumulates in cancer tissues, leads to the local production of reactive oxygen species that kill the tumor cells. Mitochondria are central coordinators of the mechanisms by which PDT induces apoptosis in the target cells. Recent studies indicate that concomitant to the permeabilization of the outer mitochondrial membrane (which leads to the release of several apoptogenic factors in the cytosol and to the activation of effector caspases), regulatory signaling pathways are activated in a photosensitizer, PDT dose and cell-dependent fashion. Signaling pathways regulated by members of mitogen activated protein kinases and their downstream targets, such as cyclooxygenase-2, appear to critically modulate cancer cell sensitivity to PDT. Understanding the molecular events that contribute to PDT-induced apoptosis, and how cancer cells can evade apoptotic death, should enable a more rationale approach to drug design and therapy.     

Study on the Isolation,Purification and Antioxidation Properties of Polysaccharides from Spirulina maxima

The emde polysaccharide was extracted from Spirulina maxima with hot water, and precipitated by ethanol after depmteinization. Two portions of refined polysaccharides (SPS I and SPS H ) were prepared after further purification on DEAE-Sephadex A-25 column chromatography, and their homogeneity was examined with Sephadex G-150 column chromatography. The ultraviolet spectm showed their characteristic absorption at 195.00 mn. In order to estimate the antioxidation activity of SPS Ⅰ and SPS Ⅱ, three systems of generating superoxide radical (O2-), lipid radical (R') and hydroxyl radical (OH') respectively in vitro were designed. The results showed that both SPS Ⅰ and SPS Ⅱ from S. maxima had significant capacity of scavenging OH' ( P < 0.05), but no effect on O2 ( P > 0.1 ); and that SPS Ⅰ could scavenge R' under lower concentration of polysaccharides (P < 0.05), while the capacity of scavenging R' of both SPS Ⅰ and SPS Ⅱ decreased in higher concentration ( P > 0.2). These results demonstrated that the significant antioxidation activity of polysaccharides from S. maxima was focused on scavenging OH', the most highly reactive one of the oxygen radicals.     

Photodynamic therapy of cancer: Search for ideal photosensitizer

Photodynamic therapy (PDT) is a minimally invasive and promising new modality to combat cancer. The method is based on selective accumulation of sensitizers in tumor cells. The high degree of selectivity offered by this modality has been applied for fluorescent diagnostics of cancer. Photosensitization of a tissue-localized sensitizer in the presence of oxygen generates cytotoxic reactive oxygen species results in the selective destruction of tumor. The PDT’s major advantages compared to traditional methods of cancer treatment are better selectivity, and low toxicity of administered drugs. This review highlights basic principles of this method, mechanisms underlying damage of tumor tissue and first and second generations of sensitizers. Future developments in PDT will include the development of new methods of treatment and diagnostics of tumor diseases.     

豆柄瘤蚜茧蜂触角感受器的扫描电镜观察(英文)

利用扫描电镜对豆柄瘤蚜茧蜂Lysiphlebus fabarum的触角感受器进行了观察, 发现有7 种感受器, 分别为毛形感受器、刺形感受器Ⅰ型、刺形感受器Ⅱ型、锥形感受器、腔锥形感受器Ⅰ型、腔锥形感受器Ⅱ型和板形感受器。毛形感受器是数量最多的感器; 除了腔锥形感受器Ⅱ型只在雌虫触角发现外, 雌、雄触角感受器的类型和结构没有较大的差别, 并且腔锥形感受器Ⅱ是数量最少的感器。     

光合作用光抑制的研究进展

概述了植物光合作用光抑制的研究进展,包括造成光抑制和光氧化的活性氧的产生和作用机理,光抑制的作用部位,以及光保护机制等,着重从三个方面讨论了植物抗光抑制的保护机理：与光系统Ⅱ天线以及叶黄素循环相关的热耗散途径,包括光呼吸、H2O-H2O循环和环式电子传递在内的电子传递途径,以及活性氧清除机制等。     

Synthesis and biological evaluation of glucose conjugated phthalocyanine as a second-generation photosensitizer

Photodynamic therapy (PDT) is a treatment method using light and photosensitizers (PSs), which is categorized as a non-invasive surgery treatment for cancers. When the tumor is exposed to a specific light, the PSs become active and generate reactive oxygen species (ROS), mainly singlet oxygen which kills nearby cancer cells. PDT is becoming more widely recognized as a valuable treatment option for localized cancers and pre-cancers of skin as it has no long-term effects on the patient. But, due to the limited penetration rate of light into the skin and other organs, PDT can’t be used to treat large cancer cells or cancer cells that have grown deeply into the skin or other organs. Hence, in this study, our focus centers on synthesizing glucose-conjugated phthalocyanine (Pc) compatible with near-infrared (NIR) irradiation as second-generation photosensitizer, so that PDT can be used in a wider range to treat cancers without obstacles.