Specificity and function of monoclonal antibodies directed against Ewing sarcoma cells

A selection of 16 monoclonal antibodies has been produced against a fresh Ewing's sarcoma (ES) tumor mixed with a permanent ES cell line. The majority of antibodies identify an 80-kDa molecule, which is not detected on healthy tissues except on certain cultured monocytes. One antibody recognize the CD2 ligand MIC2 and 2 antibodies (numbers 13 and 16) define a higher-molecular-mass antigen. Antibody 16 is also expressed on mesenchymal fibroblasts of bone marrow or fetal origin. Tumorspecific antigen expression is potentially linked to the chromosome 22 abnormality decribed in Ewing's sarcoma.     

金属螯合亲和层析纯化金属硫蛋白

将二价铜离子螯合在Chelating Sepharose Fast Flow凝胶上制成亲和层析柱,锌诱导兔肝和镉诱导小鼠肝经匀浆、乙醇处理后上柱,用pH4.0的醋酸盐缓冲液平衡,再用pH5.2不同浓度的醋酸盐缓冲液分别洗脱,可得两个金属硫蛋白(MT)洗脱峰,经确定先后为MT-2和MT-1.分离方法比传统的凝胶过滤-离子交换法简单、省时,适于实验室规模分离纯化.     

α-Domain of human metallothionein IA can bind to metals in transgenic tobacco plants

We have introduced a genetically marked Dissociation transposable element (Ds ^HPT ) into tomato (Lycopersicon esculentum) by Agrobacterium tumefaciens-mediated transformation. Probes for the flanking regions of the T-DNA and transposed Ds ^HPT elements were obtained with the inverse polymerase chain reaction (IPCR) technique and used in RFLP linkage analyses. The RFLP map location of 11 T-DNAs carrying Ds ^HPT was determined. The T-DNAs are distributed on 7 of the 12 tomato chromosomes. To explore the feasibility of gene tagging strategies in tomato using Ds ^HPT , we examined the genomic distribution of Ds ^HPT receptor sites relative to the location of two different, but very closely linked, T-DNA insertion sites. After crosses with plants expressing Ac transposase, the hygromycin phosphotransferase (HPT) marker on the Ds element and the excision markers β-glucuronidase (GUS) and Basta resistance (BAR) facilitated the identification of plants bearing germinally transposed Ds ^HPT elements. RFLP mapping of 21 transposed Ds ^HPT elements originating from the two different T-DNA insertions revealed distinct patterns of reintegration sites.     

Bacterioplankton interactions with Daphnia and algae in experimental enclosures

Development of bacterioplankton was studied by manipulation of planktivorous fish and/or nutrients in experimental enclosures in a fish pond. Grazing pressure exerted by large zooplankton (Daphnia galeata and Daphnia pulicaria) strongly influenced the counts and size distribution of bacterial populations. Morphometric analyses by scanning electron microscope revealed a shift in size distribution from larger mainly rod-type bacteria under low grazing pressure towards smaller mainly coccus-type under strong grazing pressure. The metabolic activity of bacteria measured as glucose uptake was higher under strong grazing pressure. After removal of large daphnids, the increase in bacterial density was probably the result of two additive factors: low grazing pressure and high level of dissolved organic matter (DOM) due to photosynthetic activity of more abundant algae. Composition of bacterial populations shifted toward larger, rod-type bacteria, and their metabolic efficiency measured by uptake, was lowered. The basic dimensionality of the system and interactions between variables was describe by R-mode factor analysis. The manipulated enclosures were relate with factor score.     

核酸去甲基酶AlkB在毕赤酵母中的表达纯化及在tRNA相关研究中的应用

[目的]核酸的甲基化修饰是一种常见的化学修饰形式,具有重要的生物学功能,却也在一定程度上给一些核酸研究过程带来了技术难度。tRNA上具有的大量甲基化修饰会阻碍逆转录进程,从而降低荧光定量PCR (real-time fluorescence quantitative polymerase chain reaction,RT-qPCR)和高通量测序对其的检测效率。来自大肠杆菌(Escherichia coli)的AlkB蛋白是一种多功能的脱烷基化酶,可以去除DNA和RNA上多种甲基化为代表的修饰,有望解决以上问题。[方法]针对大肠杆菌来源的AlkB,分别尝试在大肠杆菌和毕赤酵母(Pichia pastoris)表达系统中进行诱导表达和纯化,对纯化获得的AlkB进行酶学性质测定。最后以tRNA_UAU^Ile等两种tRNA为代表,研究AlkB的处理对于荧光定量PCR法检测tRNA表达水平的影响。[结果]AlkB在大肠杆菌中表达时多以包涵体形式存在,但是在毕赤酵母中可以成功分泌表达。使用镍柱分离纯化后获得了纯度高于95%的AlkB蛋白,其酶学性质参数如...     

海南潜在世界自然遗产地的突出普遍价值初探

世界自然遗产地是全球最具有保护价值的自然保护地,强调全球突出普遍价值的完整性和在全球的唯一性。世界自然遗产有助于更好地保护生态系统的完整性和原真性,促进人类与自然的可持续发展。该研究在大量文献资料的基础上,以海南潜在世界自然遗产地(海南热带雨林国家公园)原生动植物及植被群落(亚洲北缘热带雨林)为研究对象,从植被类型、物种多样性、区系组成、特有种等生物生态过程方面,评估海南潜在世界自然遗产地的全球突出普遍价值。结果表明:(1)海南潜在世界自然遗产地分布有3 653种野生维管植物,资源植物种类丰富。陆栖脊椎动物有540种,各类野生动物占全国的比例高达10%～30%,生物多样性极高。(2)植物区系独特,海南岛的热带雨林植被区划属于印度-马来雨林群系,属马来区的部分呈现出热带性和与中国华南大陆的共源性显示出明显的热带边缘性质,为中国华南植物区系与亚洲热带雨林的过渡类型。(3)植物区系中的植物物种特有性较低,特有属仅有7个,特有种仅约占岛内植物的1/10,较低的特有性表明了其大陆起源特征,是生物多样性不可替代的元素,具有鲜明的环境指示特色。该研究明确了海南潜在世界自然遗产地在全球背景下的突出普遍价值,为海南未来申遗提供科学依据和技术支撑。     

pH对生物合成超声分子影像探针气囊充放气的调控

气囊（gas vesicles,GVs）是一种存在于蓝藻及古菌等微生物中调节浮力的类细胞器纳米结构,由蛋白质外壳包裹气体组成。近年来的研究表明,气囊具有作为超声分子影像探针的潜力。然而,气囊的充放气机制并不明确,限制了生物合成超声分子影像探针的保存和气体更换。本研究发现环境pH值是调节气囊充放气的一个重要因素。其不仅可以调节藻细胞内的气囊充放气进而使微囊藻呈现不同的漂浮状态,还可对提纯的气囊充放气进行体外调节,且该调节过程可逆。该机制的阐明为生物合成超声分子影像探针的大规模生产和保存,特别对气囊中的气体进行更换以满足不同的诊疗需求提供了技术支持,助力生物合成超声造影剂在疾病诊疗中的应用。     

靶向蛋白质泛素修饰及降解在前列腺癌治疗中的机遇与挑战

前列腺癌是中国发病率增长最快的男性肿瘤,抗雄激素治疗耐药是导致前列腺癌患者预后差的主要原因。因此,解决耐药性难题是前列腺癌转化研究的关键问题。哺乳动物细胞利用泛素-蛋白酶体系统实现蛋白质的靶向降解。因此,前列腺癌中关键的癌基因如雄激素受体（AR）的上游泛素化调控因子（如去泛素化酶）是潜在的治疗靶点。然而,这些酶具有较广的底物谱系,存在脱靶的可能性。近来,基于泛素-蛋白酶体系统开发的蛋白质降解靶向嵌合体（proteolysis-targeting chimeras,PROTAC）技术是最具前景和革命性的新型抗癌药物研发技术,能够利用特定E3泛素连接酶对靶蛋白进行降解而不影响其他底物。与传统小分子抑制剂相比,PROTAC分子在克服耐药性以及针对不可成药的靶点方面拥有巨大优势。目前,针对AR的PROTAC降解剂已在II期临床取得了成功,靶向蛋白质泛素化及降解途径的新技术将有望为前列腺癌的临床治疗带来新的突破。     

A chromosome-level genome assembly enables the identification of the follicule stimulating hormone receptor as the master sex-determining gene in the flatfish Solea senegalensis

Sex determination (SD) shows huge variation among fish and a high evolutionary rate, as illustrated by the Pleuronectiformes (flatfishes). This order is characterized by its adaptation to demersal life, compact genomes and diversity of SD mechanisms. Here, we assembled the Solea senegalensis genome, a flatfish of great commercial value, into 82 contigs (614 Mb) combining long- and short-read sequencing, which were next scaffolded using a highly dense genetic map (28,838 markers, 21 linkage groups), representing 98.9% of the assembly. Further, we established the correspondence between the assembly and the 21 chromosomes by using BAC-FISH. Whole genome resequencing of six males and six females enabled the identification of 41 single nucleotide polymorphism variants in the follicle stimulating hormone receptor (fshr) consistent with an XX/XY SD system. The observed sex association was validated in a broader independent sample, providing a novel molecular sexing tool. The fshr gene displayed differential expression between male and female gonads from 86 days post-fertilization, when the gonad is still an undifferentiated primordium, concomitant with the activation of amh and cyp19a1a, testis and ovary marker genes, respectively, in males and females. The Y-linked fshr allele, which included 24 nonsynonymous variants and showed a highly divergent 3D protein structure, was overexpressed in males compared to the X-linked allele at all stages of gonadal differentiation. We hypothesize a mechanism hampering the action of the follicle stimulating hormone driving the undifferentiated gonad toward testis.     

Low genetic diversity and population connectivity fuel vulnerability to climate change for the Tertiary relict pine Pinus bungeana

Endemic species are important components of regional biodiversity and hold the key to understanding local adaptation and evolutionary processes that shape species distributions. This study investigated the biogeographic history of a relict conifer Pinus bungeana Zucc. ex Endl. confined to central China. We examined genetic diversity in P. bungeana using genotyping-by-sequencing and chloroplast and mitochondrial DNA markers. We performed spatial and temporal inference of recent genetic and demographic changes, and dissected the impacts of geography and environmental gradients on population differentiation. We then projected P. bungeana's risk of decline under future climates. We found extremely low nucleotide diversity (average π 0.0014), and strong population structure (global F_ST 0.234) even at regional scales, reflecting long-term isolation in small populations. The species experienced severe bottlenecks in the early Pliocene and continued to decline in the Pleistocene in the western distribution, whereas the east expanded recently. Local adaptation played a small (8%) but significant role in population diversity. Low genetic diversity in fragmented populations makes the species highly vulnerable to climate change, particularly in marginal and relict populations. We suggest that conservation efforts should focus on enhancing gene pool and population growth through assisted migration within each genetic cluster to reduce the risk of further genetic drift and extinction.