Binding of Chlorpromazine to S-100 Protein

Chlorpromazine (CPZ) induces in S-100 conformational changes resulting in the exposure of titratable SH groups of the protein to the solvent. This effect is even greater in the presence of Mg2+ +/- Ca2+. S-100 possesses binding sites for CPZ. The binding of CPZ to 3 microM S-100 is half-saturated by 0.18 microM CPZ in the presence of Mg2+ plus Ca2+ and by 0.24 microM CPZ in the presence of Mg2+ plus EGTA. The extent of the binding is greater in the presence of Ca2+ than in the presence of EGTA, especially at low CPZ concentrations.     

Anti-tumour components of the culture filtrates from Tricholoma sp.

The anti-tumour component (Fraction A) found in the culture filtrates of a local mushroom, Tricholoma sp. (strain STC20-T1), was purified using DEAE-cellulose ion exchange chromatography and Sepharose CL-4B gel filtration. Of its two purified sub-fractions, A-1 and A-2, only the latter showed anti-tumor activity. When Fraction A-2 was treated with cetyltrimethylammonium hydroxide and chloroform/butanol (24:1, v/v), it behaved as a proteinbound polysaccharide, with a molecular mass estimated to be 154 kDa by gel filtration. It contained 40% polysaccharide, which consisted of fucose, galactose, glucose, arabinose and mannose, and 30.5% protein, the amino-acid composition of which was determined. Fraction A-2 could inhibit the growth of Sarcoma-180 implanted in mice intraperitoneally and subcutaneously, with no sign of toxicity, at a dose of 20 mg/kg.day for 10 days.     

Mammary serum factor initiates cell growth in 3T3 cell variants which are non-responsive to EGF

The structural organization of the histone-containing spermatozoa of the goldfish C. auratus is studied. Chemical fractionation shows that the five standard histones are present. Histone H1 subfractions are also similar to those found in other organisms. This is the first organism studied in which no peculiar basic protein is found in spermatozoa, since in all the organisms described up to now, unique protein components are always present, either alone or accompanied by somatic-like histones. Ultrastructural studies show that this chromatin is organized as a bundle of fibers of about 25 nm diameter, which upon spreading give the typical ‘beads-on-a-string’ appearance. Nuclease digestion demonstrates a repeat length of 205 base pairs (bp), slightly longer than in somatic tissues, but shorter than in echinoderm spermatozoa.     

Intercellular communications within the rat anterior pituitary. XVI: Postnatal changes of distribution of S-100 protein positive cells,connexin 43 and LH-RH positive sites in the pars tuberalis of the rat pituitary gland. An immunohistochemical and electron microscopic study

The architecture of luteinizing hormone-releasing hormone (LH-RH) nerve ends and the S-100 protein containing folliculo-stellate cells forming gap junctions in the pars tuberalis is basically important in understanding the regulation of the hormone producing mechanism of anterior pituitary glands. In this study, intact male rats 5–60 days old were prepared for immunohistochemistry and electron microscopy. From immunostained sections, the S-100 containing cells in pars tuberalis were first detected on day 30 and increased in number to day 60; this was parallel to the immunohistochemical staining of gap junction protein, connexin 43. LH-RH positive sites were clearly observed on just behind the optic chiasm and on the root of pituitary stalk on day 30. On day 60, the width of layer increased, while follicles and gap junctions were frequently observed between agranular cells in 10 or more layers of pars tuberalis.     

中国各地不同枣树品种上枣疯病植原体的PCR检测及分子变异分析

摘要：【目的】检测不同地区枣树品种上的枣疯植原体侵染及保守基因序列的变异。【方法】利用植原体16S rDNA的通用引物R16mF2／R16mR1、16S-23S间区序列(SR)的通用引物SR1/SR及secY基因引物FD9f/r,通过PCR检测采自国内7个地区14个枣树品种上的32个枣疯病和4个酸枣丛枝病样品。将PCR产物进行直接或克隆测序,结合已报导的测序数据,进行序列同源性和系统进化分析。【结果】所有枣疯病样品中均检测到植原体;皆属于榆树黄化16S rV-B亚组,与我国重阳木丛枝和樱桃致死黄化遗传关系     

Selenium Pretreatment Enhances the Radioprotective Effect and Reduces the Lethal Toxicity of Wr-2721

Although WR-2721, S-2-(3-aminopropylamino)ethylphosphorothioic acid, is an effective radioprotector, its use is limited by its toxicity. Combining WR-2721 with other agents might decrease its toxicity and/or increase its effectiveness. The effect of selenium (Se) pretreatment on the acute toxicity and radioprotective effect of WR-2721 was studied in male CD2F1 mice. Injection of 1.6mg/kg Se 24 hr before WR-2721 (800-1200 mg/kg, IP) decreased the lethality of WR-2721 significantly. Lower doses of Se were also effective, but simultaneous administration was not effective. Se injection alone (1.6 mg/kg) 24 hr before cobalt-60 irradiation increased the survival (dose reduction factor, DRF = 1.1) significantly. A synergistic effect on post-irradiation survival was observed when Se was injected 24 hr before WR-2721 (200-600 mg/ kg IP before irradiation). For example, after exposure to 22 Gy (1 Gy/min), 30-day survival was 100% when mice were treated with both Se and 600mg/kg WR-2721, and was 13% with WR-2721 alone. The DRF after 400 mg/kg WR-2721 was 2.6 with Se compared to 2.2 without Se pretreatment. Alkaline phosphatase activity in bone marrow cells and serum was significantly depressed after treatment with 1.6 mg/kg Se, suggesting that a retardation of conversion of WR-2721 to its active free sulfhydryl form through the action of alkaline phosphatase might be partly responsible for the effects of Se. Other possible mechanisms related to the antioxidant properties of Se are under investigation.     

基于16S-23S rDNA 间隔区序列（ITS）、REP序列的基因指纹图谱及UPGMA聚类法的拟诺卡菌属分类方法

拟诺卡菌属（Nocardiopsis）是拟诺卡菌科（Nocardiopsaceae） 的唯一属．该属内进行物种鉴别时通常是在多相分类方法基础上,以全基 因组杂交同源性在70%以下的为不同物种,此为国际公认的定种标准;但在 进行大量菌株的比对时操作比较复杂,于是多种基于DNA的基因图谱技术发 展起来．本实验利用适宜引物,对拟诺卡菌属15株基准株基因组DNA的16S -23S rDNA 间隔区序列（ITS）和REP序列进行了扩增,获得了两种基因指 纹图谱,同时根据UPGMA聚类法构建了相应的进化距离树图．结果表明,对 于拟诺卡菌属中不同物种的区分,两种基因图谱技术的分辨力相当,均可 以较好的呈现物种间差异,可以作为拟诺卡菌属菌株多相分类的组成部分 ,应用于物种水平的分类与鉴定．     

Novel lineages of Prochlorococcus and Synechococcus in the global oceans

Picocyanobacteria represented by Prochlorococcus and Synechococcus have an important role in oceanic carbon fixation and nutrient cycling. In this study, we compared the community composition of picocyanobacteria from diverse marine ecosystems ranging from estuary to open oceans, tropical to polar oceans and surface to deep water, based on the sequences of 16S-23S rRNA internal transcribed spacer (ITS). A total of 1339 ITS sequences recovered from 20 samples unveiled diverse and several previously unknown clades of Prochlorococcus and Synechococcus. Six high-light (HL)-adapted Prochlorococcus clades were identified, among which clade HLVI had not been described previously. Prochlorococcus clades HLIII, HLIV and HLV, detected in the Equatorial Pacific samples, could be related to the HNLC clades recently found in the high-nutrient, low-chlorophyll (HNLC), iron-depleted tropical oceans. At least four novel Synechococcus clades (out of six clades in total) in subcluster 5.3 were found in subtropical open oceans and the South China Sea. A niche partitioning with depth was observed in the Synechococcus subcluster 5.3. Members of Synechococcus subcluster 5.2 were dominant in the high-latitude waters (northern Bering Sea and Chukchi Sea), suggesting a possible cold-adaptation of some marine Synechococcus in this subcluster. A distinct shift of the picocyanobacterial community was observed from the Bering Sea to the Chukchi Sea, which reflected the change of water temperature. Our study demonstrates that oceanic systems contain a large pool of diverse picocyanobacteria, and further suggest that new genotypes or ecotypes of picocyanobacteria will continue to emerge, as microbial consortia are explored with advanced sequencing technology.     

Catalytic promiscuity of a bacterial α-N-methyltransferase

The posttranslational methylation of N-terminal α-amino groups (α-N-methylation) is a ubiquitous reaction found in all domains of life. Although this modification usually occurs on protein substrates, recent studies have shown that it also takes place on ribosomally synthesized natural products. Here we report an investigation of the bacterial α-N-methyltransferase CypM involved in the biosynthesis of the peptide antibiotic cypemycin. We demonstrate that CypM has low substrate selectivity and methylates a variety of oligopeptides, cyclic peptides such as nisin and haloduracin, and the ε-amino group of lysine. Hence it may have potential for enzyme engineering and combinatorial biosynthesis. Bayesian phylogenetic inference of bacterial α-N-methyltransferases suggests that they have not evolved as a specific group based on the chemical transformations they catalyze, but that they have been acquired from various other methyltransferase classes during evolution.