Purification and electron microscopic characterization of the membrane subunit (IICB(Glc)) of the Escherichia coli glucose transporter

The glucose transporter of the bacterial phosphotransferase system mediates sugar transport across the cytoplasmic membrane concomitant with sugar phosphorylation. It consists of a cytoplasmic subunit IIA(Glc) and the transmembrane subunit IICB(Glc). IICB(Glc) was purified to homogeneity by urea/alkali washing of membranes and nickel-chelate affinity chromatography. About 1.5 mg highly pure IICB(Glc) representing 77% of the total activity present in the membranes was obtained from 8g (wet weight) of cells. IICB(Glc) was reconstituted into lipid bilayers by temperature-controlled dialysis to yield small 2D crystals and by a rapid detergent-dilution procedure to yield densely packed vesicles. Electron microscopy and digital image processing of the negatively stained 2D crystals revealed a trigonal lattice with a unit cell size of a = b = 14.5 nm. The unit cell morphology exhibited three dimers of IICB(Glc) surrounding the threefold symmetry center. Single particle analysis of IICB(Glc) in proteoliposomes obtained by detergent dialysis also showed predominantly dimeric structures.     

Genomic mapping of chromosomal region 2p15-p21 (D2S378-D2S391): integration of Genemap'98 within a framework of yeast and bacterial artificial chromosomes

The region of chromosome 2 encompassed by the polymorphic markers D2S378 (centromeric) and D2S391 (telomeric) spans an approximately 10-cM distance in cytogenetic bands 2p15-p21. This area is frequently involved in cytogenetic alterations in human cancers. It also harbors the genes for several genetic disorders, including Type I hereditary nonpolyposis colorectal cancer (HNPCC), familial male precocious puberty (FMPP), Carney complex (CNC), Doyne's honeycomb retinal dystrophy (DHRD), and one form of familial dyslexia (DYX-3). Only a handful of known genes have been mapped to 2p16. These include MSH2, which is responsible for HNPCC, FSHR, the gene responsible for FMPP, EFEMP-1, the gene mutated in DHRD, GTBP, a DNA repair gene, and SPTBN1, nonerythryocytic beta-spectrin. The genes for CNC and DYX-3 remain unknown, due to lack of a contig of this region and its underrepresentation in the existing maps. This report presents a yeast- and bacterial-artificial chromosome (YAC and BAC, respectively) resource for the construction of a sequence-ready map of 2p15-p21 between the markers D2S378 and D2S391 at the centromeric and telomeric ends, respectively. The recently published Genemap'98 lists 146 expressed sequence tags (ESTs) in this region; we have used our YAC-BAC map to place each of these ESTs within a framework of 40 known and 3 newly cloned polymorphic markers and 37 new sequence-tagged sites. This map provides an integration of genetic, radiation hybrid, and physical mapping information for the region corresponding to cytogenetic bands 2p15-p21 and is expected to facilitate the identification of disease genes from the area.     

DAZ家族新成员BOULE蛋白的结构与功能

BOULE蛋白是2001年发现的DAZ家族的新成员,是人类精子发生过程中减数分裂的关键调控因子. BOULE基因表达的改变或BOULE蛋白的缺乏可引起减数分裂阻滞和精子生成障碍,从而导致无精子症并产生不育. BOULE蛋白的一级结构中含有DAZ家族的特征结构域,包括DAZ重复和RNA结合域（RBM）,因此,将其列为继DAZ、DAZL之后DAZ家族的第3个成员.本文对BOULE的发现过程、结构和定位进行了总结回顾,并重点介绍了其在精子发生减数分裂中的作用及其作用机制.     

Analysis of fungal community structure in the soil of Zoige Alpine Wetland

To understand the soil fungal community diversity in different zones of the Zoige Alpine Wetland, BIOLOG analysis and traditional culture method were employed in our research. Three sample sites namely the Conservatory Station up-hill slope (CSUS), the Flower Lake side (FLS) and the Conservatory Station down slope (CSDS) with increasing by water content were investigated. The results of BIOLOG showed that fungal catabolic richness index (S) and Shannon diversity index (H) increasingly rose with water content augmented from CSUS to CSDS, while different from the former tendency, the fungal catabolic activity was highest at CSDS and lowest at FLS. Principal component analysis (PCA) results demonstrated the functional diversity of fungal community varied among the three sample sites, showing us more similarity between CSDS and FLS, and considerable difference between CSUS and the former two sites. The outcome of traditional culture method illustrated the number of soil fungi increased from CSUS to CSDS, while the sort of fungal species that could be cultured did not show much difference among the three sample sites.     

Electron-Microscope Observation on the Pollen Development of Male Sterility Wheat Induced by Ethrel

The pollen development of male sterility wheat induced by Ethrel was studied in comparison with that of normal wheat by transmission and scanning electron-microscope. The results obtained are summarized as follows: 1. The primary morphological changes of abortive wheat pollen after treatment with Ethrel took place in the vacuole stage. The materials of cytoplasm were rarefied. All kinds of the cell organelles and vacuoles became degenerated and disorganized. Inside a small number of cell nuclei, chromatin granules coagulated irregularly. The number and the activity of the Ubisch bodices became reduced evidently. 2. In the mature stage, the differences between the treated wheat and normal wheat became even more striking. The normal pollens were spherical in sharp, and full of starch granules. The treated pollen were monstrous. There was a large empty vacuole in every abortive pollen cell, in which the starch granules were smaller and fewer than these in the normal ones. The nuclei and cytoplasm in some of the abortive pollens were degenerated, leaving only the cell walls. 3. Under scanning electron microscope, it was discovered that the normal wheat pollen were spherical or oval. The germinated pores jutted. The round-openings of the pores could be clearly seen. The abortive pollen induced by Ethrel looked like some shrunken balls, and became deformed and were blocked up. 4. On discussion of the mechanism of the Ethrel-induced male sterility in wheat, the authors suggest that special attention should be paid to the changes of the Ubisch bodies and the vacuoles.     

A risk signature-based on metastasis-associated genes to predict survival of patients with osteosarcoma

Osteosarcoma (OS) is the most common primary solid malignant bone tumor, and its metastasis is a prominent cause of high mortality in patients. In this study, a prognosis risk signature was constructed based on metastasis-associated genes. Four microarrays datasets with clinical information were downloaded from Gene Expression Omnibus, and 256 metastasis-associated genes were identified by limma package. Further, a protein-protein interaction network was constructed, and survival analysis was performed using data from the Therapeutically Applicable Research to Generate Effective Treatments data matrix, identifying 19 genes correlated with prognosis. Six genes were selected by the least absolute shrinkage and selection operator regression for multivariate cox analysis. Finally, a three-gene (MYC, CPE, and LY86) risk signature was constructed, and datasets GSE21257 and GSE16091 were used to validate the prediction efficiency of the signature. The survival times of low- and high-risk groups were significantly different in the training set and validation set. Additionally, gene set enrichment analysis revealed that the genes in the signature may affect the cell cycle, gap junctions, and interleukin-6 production. Therefore, the three-gene survival risk signature could potentially predict the prognosis of patients with OS. Further, proteins encoded by CPE and LY86 may provide novel insights into the prediction of OS prognosis and therapeutic targets.     

Transformation of trichloroethylene by sulfate-reducing cultures enriched from a contaminated subsurface soil

Summary Trichloroethylene (TCE) was reductively dechlorinated to cis-1,2-dichloroethylene (cDCE) by sulfate-reducing cultures enriched from a contaminated subsurface soil. The highest observed transformation rate of TCE was 213 mol l^–1 per day at 35° C. The predominant biotransformation product was cDCE. However, further dechlorination of cDCE was not observed in most of the cultures. Methane production was insignificant and active sulfate reduction was achieved by maintaining excess sulfate. A comparison of sodium sulfide and sodium dithionite for their effect on the transformation of TCE revealed that the latter is a better reducing agent. The extent of TCE transformation in 25 days was ca. 20% higher in the dithionite-amended cultures. A decrease in the rate and extent of TCE transformation was observed with an increase in the concentration of bromoethanesulfonate up to 50 mabetm. Offprint requests to: S. G. Pavlostathis     

AMPA受体与谷氨酸在大鼠三叉神经尾侧亚核内分布的免疫组织化学研究

本文用免疫组织化学ＡＢＣ法调查了４种ＡＭＰＡ受体亚单位（ＧｌｕＲ１、２／３、４）和谷氨酸（Ｇｌｕ）在大鼠三叉神经尾侧亚核（Ｖｃ）内的分布及其匹配关系。我们发现,ＧｌｕＲ１和２／３免疫阳性胞体和纤维密集分布于Ｖｃ的Ⅱ层和Ⅲ层外侧部,在Ｖｃ的其余各层呈散在性分布。ＧｌｕＲ４免疫阳性胞体和纤维在Ｖｃ各层均无分布。Ｇｌｕ免疫阳性胞体分布于Ｖｃ各层,尤以浅层（Ⅰ、Ⅱ层）密集,Ｇｌｕ免疫阳性纤维及终末结构主要分布于Ｖｃ浅层。结果表明,Ｇｌｕ免疫阳性纤维及终末样结构与ＡＭＰＡ受体免疫阳性胞体和纤维在Ｖｃ浅层的分布总体上是相互匹配的,但ＡＭＰＡ受体各亚单位在Ｖｃ内的分布存在明显的差异。本文提示,Ｖｃ内的Ｇｌｕ可能通过作用于不同的ＡＭＰＡ受体亚单位而发挥其多种生理功能