Automated system for capture and detection of nucleic acids.

A fully automated nucleic acid analysis system is described, which offers positive sample identification, improved sensitivity and reduced user interaction compared to conventional techniques. The system relies on the sequence-specific capture of DNA onto solid-phase particles, confirming product identity without the problems of interpretation and lack of sequence information inherent in gel-based analyses. The system can be used for sequence confirmation, mutation analysis and semiquantitative detection of PCR products.     

免疫毒素的抗肿瘤研究

免疫毒素是由具有导向能力的载体（抗体或细胞因子）和具有细胞毒性的分子（毒素）偶联而成的具有特异性细胞杀伤能力的杂合分子,是一种靶向药物。免疫毒素首先利用肿瘤细胞上导向分子的受体与细胞结合,然后进入细胞,再由毒素发挥蛋白质合成抑制作用,最终导致靶细胞死亡。与其他抗肿瘤药物相比,免疫毒素具有毒性强和特异性高的优点,在肿瘤治疗中显示出巨大的应用前景。简要概述了免疫毒素的作用机理、制备及其抗肿瘤研究进展。     

Identification of quantitative trait loci controlling winter hardiness in an annual × perennial ryegrass interspecific hybrid population

Winter hardiness is a quantitative trait and the lack of it limits geographic distribution of ryegrass. Improving winter hardiness is an important breeding goal in ryegrass breeding programs. An understanding of the genetic basis for the component traits of winter hardiness would allow more efficient selection. A three-generation interspecific population of an annual × perennial ryegrass consisting of 152 progenies was used to map quantitative trait loci (QTL) that control winter hardiness-related traits including fall growth (FG), freezing tolerance (FT), and winter survival (WS) over 2 years. A total of 39 QTL were identified for the three traits from both the female parental (MFA) and the male parental (MFB) maps, of which 13 were for FG, 6 for FT, and 20 for WS. The proportion of phenotypic variation explained by individual QTL ranged from 10.4 to 22.1%. Both FG and FT were positively correlated with WS. Common QTL were detected between FG, FT, and WS. The QTL associated with WS on linkage groups (LGs) 4 and 5, and the QTL for FT on LG 5 were consistently identified over years and maps. These consistent QTL might serve as potential tools for marker-assisted selection to improve ryegrass winter hardiness.     

Nucleotide sequence of the maize transposable element Mul

A cloned DNA fragment from the maize allele Adhl-S3034 contains all of Mul, an insertion element involved in Robertson's Mutator activity. The element is 1367 base pairs (bp) long and is flanked by nine bp direct repeats of insertion site DNA. It has inverted terminal repeats of 215 and 213 bp showing 95% homology. Within the element are two direct repeats of 104 bp showing 96% homology. Four open reading frames (ORFs) were found, two in each DNA strand. Mul can be divided into two halves, each containing one terminal inverted repeat, an internal direct repeat, and two overlapping ORFs. The GC content of each half is high (70%), while that of a central 60 base portion of the element is low (26%). The central region contains the only sequence resembling the TAATA Goldberg and Hogness eukaryotic promoter signal. Multiple copies of DNA sequences related to Mul found in Mutator maize plants are generally similar in organization to the cloned element. A larger version containing a discrete 300 to 400 base pair insertion was found in some Mutator lines.     

Semiconductor nanocrystal probes for human metaphase chromosomes

To improve signal stability and quantitation, an optically stable, novel class of fluorophore for hybridization analysis of human metaphase chromosomes is demonstrated. Detection of hybridization sites in situ was based on fluorescence from streptavidin-linked inorganic crystals of cadmium selenide [(CdSe)ZnS]. Fluorescence of nanocrystal fluorophores was significantly brighter and more photostable than organic fluorophores Texas Red and fluorescein. Thus, semiconductor nanocrystal fluorophores offer a more stable and quantitative mode of fluorescence in situ hybridization (FISH) for research and clinical applications.     

Sequence of human eosinophil-derived neurotoxin cDNA: identity of deduced amino acid sequence with human nonsecretory ribonucleases

Several clones of human eosinophil-derived neurotoxin (EDN) cDNA have been isolated from a lambda gt10 cDNA library prepared from mRNA derived from noninduced HL-60 cells. The amino acid (aa) sequence deduced from the coding sequence of the EDN cDNA is identical to the aa sequence of urinary nonsecretory RNase. Comparison of the aa and/or nucleotide (nt) sequences of EDN and other proteins possessing ribonucleolytic activity, namely bovine seminal RNase, human and rat pancreatic RNases, eosinophil cationic protein (ECP), and human angiogenin, shows extensive identity at half-cystine residues and at aa of active sites. Differences in aa sequences at the active sites are often the result of single nt changes in the codons. The data presented here support the concept of a RNase gene superfamily containing secretory and nonsecretory RNases, angiogenin, EDN and ECP.     

DNA diagnosis of human leishmaniasis

Early identification of the causal agent of human leishmaniasis is difficult even in a well-equipped hospital. This makes early treatment of cases more difficult, and also adds to the problem of accurately assessing the prevalence and incidence of the disease. Incrimination of vector species of sandfies and reservoir hosts is also complicated by difficulties in detecting and identifying the infective organisms. Although the importance of leishmantasis is now well-recognized, improved methods of diagnosis have been much in demand (Box 1). In this article. Douglas Barker reviews progress in developing diagnostic DNA probes for the parasites, that are suitable for use even in field areas.     

Sequential gel electrophoretic analysis of esterase-2 in two populations of Drosophila buzzatii

Sequential electrophoresis, using three different buffer systems on cellulose acetate gels, was used to characterize the allelic variation for esterase-2 in two populations of D. buzzatii in Australia that are separated by 550 km. Twenty-five alleles were detected, of which nine were unique to one population, eight unique to the other, and only eight were common to both populations. Allele frequencies within each population were significantly different between the two major chromosome sequences (standard and j inversion), and for each chromosome sequence allele frequencies were significantly different between populations. Observed allelic frequency distributions were not significantly different from those predicted for selective neutrality using the homozygosity test statistic. However, estimates of the effective sizes of the populations derived from their observed differentiation, together with the history of the species in Australia, provide support for some form of balancing selection affecting at least some of the alleles.     

利用伴刀豆球蛋白检测O-甘露糖基化

目的:基于伴刀豆球蛋白A(ConA)特异性识别并结合甘露糖的特性,建立一种检测O-甘露糖基化的方法,为酵母等宿主表达蛋白的O-糖基化提供一种高效筛选和分析的方法。方法:利用糖苷酶F(PNGF)切除检测蛋白的N-糖链,排除N-糖基化的干扰;通过Q阴离子交换柱和ConA Sepharose 4B柱纯化Western印迹膜封闭蛋白牛血清白蛋白(BSA),除去BSA中甘露糖修饰的蛋白的干扰,优化膜封闭条件;利用辣根过氧化物酶标记的ConA检测具有低甘露糖型N-糖基化修饰能力的毕赤酵母GJK01-HL(Δoch1)表达的抗Her-2抗体是否存在O-甘露糖基化现象。结果:通过PNGF酶切处理,可以完全去除糖蛋白的N-糖链的干扰;BSA经过Q阴离子交换柱和ConASepharose 4B柱纯化后,除去了大部分甘露糖蛋白,可作为封闭蛋白;用建立的方法检测,发现毕赤酵母工程菌GJK01-HL(Δoch1)表达的抗Her-2抗体存在O-甘露糖基化现象。结论:本方法是研究糖蛋白是否发生O-甘露糖基化的有效检测手段,可用于酵母等表达蛋白的O-糖基化的高效筛选和分析。