Application of Xenopus laevis in ecotoxicology (I)—Introduction and quality control of laboratory animal

The aim of the series of papers is to discuss the application of Xenopus laevis, as model animal in biology, in ecotoxicology. X. laevis as model animal is wildly used in biological study and has provided a lot of relating data because of many advantages, such as living in water and being easily maintained, laying eggs in the whole year, and externally fertilizing and developing. Embryos and larvae of X. laevis like other amphibians are directly exposed in the aquatic environment and sensitive to pollutants. In addition, sex differentiation and sex organ development of X. laevis are sensitive to sex hormones and endocrine disruptors with sex hormone activities, which enable X. laevis to be used in studies on sex hormone disruption and reproductive toxicity of endocrine disruptors. Metamorphic development of X. laevis is very sensitive to thyroid hormones and thyroid disruptors, which enables X. laevis to be used for evaluating thyroid disruptors. Also, X. laevis ecotoxicology can be linked with amphibian population declines and malformed frog occurrence, being one of the hotspots in ecology. Thus, more and more laboratories have introduced X. laevis to ecotoxicological study. The quality of laboratory animals correlates with scientificity and reliability of results from animal experiments. It is especially important for toxicology. Quality control of X. laevis involving several factors such as water and food is discussed in this paper.     

全氟辛磺酸对于爪蟾的甲状腺激素干扰效应

运用两栖类变态实验(AMA)研究了全氟辛磺酸(PFOS)对于非洲爪蟾(Xenopus laevis)蝌蚪的生长、变态和甲状腺组织结构的影响.结果显示,与对照组相比,7d后,10,50和250μg.L-1PFOS暴露组蝌蚪的后肢长分别减小了17%,11%和18%,蝌蚪的发育延缓了1~2个阶段;19d后,10,50和250μg.L-1PFOS组蝌蚪的体重分别增加了17%,10%和20%,体长分别增加了5%,4%和6%,而10μg.L-1和250μg.L-1PFOS组蝌蚪的后肢长分别减小了12%和13%;暴露组甲状腺组织结构出现滤泡数目减少、上皮细胞增生、胶质减少甚至滤泡溶通等现象.结论是,在本实验浓度下,PFOS对于非洲爪蟾的蝌蚪生长有促进作用,对于变态发育过程却有抑制作用.参照AMA的方法,可以判断PFOS为抗甲状腺激素干扰物.     

海链藻属一新种和二新变种

本文报道了厦门港微型硅藻分类研究中观察到的海链藻属1新种和2新变种:平滑海链藻(Thalassiosira laevis)与其它海链藻的最主要区别在于孔纹只分布于壳缝,其内为平滑无纹区,成对海链藻小型变种(T.binata var.minor)和成对海链藻双对变种(T.bisata var.bibinata)与典型种的主要区别分别是壳缘支持突紧靠壳缘和完缘有2对成对突起。     

非洲爪蟾蜍变态期变态异常个体的性腺发育

作者对16只变态期变态异常的非洲爪蟾幼体的性腺进行了解剖及细胞学的观察.实验结果表明,变态异常个体的性腺发育与同龄正常发育者完全一致,而与其身体的外形,即个体的大小及完全变态与否没有密切关系.     

两种硝酸盐浓度下威氏海链藻和盐生杜氏藻硝酸还原酶活力研究

把盐生杜氏藻(Dunaliella salina)和威氏海链藻(Thalassiosira weissfilgii)培养在两种硝酸盐浓度下(800μmol／L和200μmol／L),比较研究了它们在培养液中硝酸盐及亚硝酸盐的变化及细胞硝酸还原酶活力变动情况．结果表明,在两种硝酸盐浓度下,两种微藻培养液中硝酸盐及亚硝酸盐的变化基本相同．在高硝酸盐浓度下,两种微藻培养液中的硝酸盐减少并维持较高的浓度,且细胞叶绿素a含量较高;而在低硝酸盐浓度下,培养液中的硝酸盐在培养的第二天即被耗尽,且细胞叶绿素a含量很低．培养液中亚硝酸盐的变化在高浓度呈现逐渐增加的趋势,而在低浓度则呈现先增加后减少的趋势;两种微藻的硝酸还原酶活力在培养的第二天即达到最大值,随后迅速下降并维持一低值,但威氏海链藻的硝酸还原酶活力要略高于盐生杜氏藻．本研究结果表明,在不同硝酸盐浓度下藻类细胞内部的硝酸盐的吸收同化机制不同,从而导致营养盐的变化也各不相同．     

Identification of inhibitor of apoptosis specific DNase in Xenopus egg extract

When added with cytochrome c, Xenopus laevis egg extract XS-150 can induce exogenous nuclei undergoing apoptosis. Apoptosis specific DNase XAD was activated during this process, and cut chromatin between nucleosome, leading to DNA Ladder in electrophoresis. Our results showed that an inhibitor of XAD, IXAD, exists abundantly in normal egg extract, its molecular weight is about 40 ku. Normally, IXAD exists either in the form of dimmer or in complex with XAD. It was degraded during apoptosis, releasing active XAD. The results of Western assay and cross-inhibition showed that IXAD was likely homologous to DFF45 in structure and function. At the same time, these results also indicated that the pathway in apoptosis was conserved in evolution.     

卵母细胞在离子通道研究中的应用

由于非洲爪蟾卵母细胞体积较大，故其蛋白质和RNA合成活性很高，、同时，卵母细胞本身仅有很少几种内源性通道和受体，因此可以忠实、高效地表达多种类型的外源性通道和受体、非洲爪蟾卵母细胞现已成为一种研究外源性离子通道基因的工具，在分析多亚基通道翻译后的加工和组装、检测突变通道特性、比较不同组织来源的通道特性、检测第二信使系统对通道功能的调制、分析和鉴定编码通道蛋白的克隆基因等方面有暑广泛的应用。     

爪蟾胚胎发生中角蛋白的表达

本文应用二株抗角蛋白单克隆抗体(MAb D10为抗爪蟾角蛋白,MAb AF5为抗人角蛋白)对爪蟾卵母细胞、受精卵、不同发育期胚胎作免疫转移印迹观察,研究其角蛋白多肽亚单位的组成。发现不同发育期胚胎角蛋白表达有变化。同时应用免疫组织化学染色技术研究角蛋白在胚胎中的分布。发现角蛋白分布于表皮、脊索、嗅板、垂体原基、粘腺、咽上皮、神经管内表面等部位。     

基于USB的卵母细胞电压钳同步数据采集和分析软件设计

介绍了基于USB接口的卵母细胞电压钳系统的数据采集分析系统,应用Delphi语言开发了系统的人机操作实验界面,探讨了电压钳的USB同步传输、数据采集和和显示的实现方法.在细胞模型测试中,电压钳放大器的跨膜电流分辨达到了0.01nA,噪声测试低于10pA.在非洲爪蟾卵母细胞表达Kv4.2钾通道实验中,记录跨膜电流波形清晰,数据分析可靠.与国外同类仪器相比:该系统操作简单,价格低,数据采集和分析方便,适用于卵母细胞表达实验.