Computational identification of obligatorily autocatalytic replicators embedded in metabolic networks

Background  

If chemical A is necessary for the synthesis of more chemical A, then A has the power of replication (such systems are known as autocatalytic systems). We provide the first systems-level analysis searching for small-molecular autocatalytic components in the metabolisms of diverse organisms, including an inferred minimal metabolism.     

贵州小型猪肠菌群失调模型的制备

目的 探索小型猪肠菌群失调模型的制备方法.方法 分别采用大黄和氨苄青霉素灌服,通过检测贵州小型猪新鲜粪便中双歧杆菌、乳酸杆菌、肠杆菌、肠球菌的数量,了解其肠菌群变化情况.结果 两种方法都可导致贵州小型猪肠菌群改变.两组相比,大黄组菌群变化速度较快、持续时间较短;氨苄青霉素组菌群变化速度较慢、持续时间较长.结论 两种方法均可制备比较稳定的贵州小型猪肠菌群失调模型,但具体表现不尽相同,应用时可根据需要选择.     

Synthesis of variously coupled conjugates of D-glucose, 1,3,4-oxadiazole, and 1,2,3-triazole for inhibition of glycogen phosphorylase

5-(O-Perbenzoylated-β-D-glucopyranosyl)tetrazole was obtained from O-perbenzoylated-β-D-glucopyranosyl cyanide by Bu(3)SnN(3) or Me(3)SiN(3)-Bu(2)SnO. This tetrazole was transformed into 5-ethynyl- as well as 5-chloromethyl-2-(O-perbenzoylated-β-D-glucopyranosyl)-1,3,4-oxadiazoles by acylation with propiolic acid-DCC or chloroacetyl chloride, respectively. The chloromethyl oxadiazole gave the corresponding azidomethyl derivative on treatment with NaN(3). These compounds were reacted with several alkynes and azides under Cu(I) catalysed cycloaddition conditions to give, after removal of the protecting groups by the Zemplén protocol, β-D-glucopyranosyl-1,3,4-oxadiazolyl-1,2,3-triazole, β-D-glucopyranosyl-1,2,3-triazolyl-1,3,4-oxadiazole, and β-D-glucopyranosyl-1,3,4-oxadiazolylmethyl-1,2,3-triazole type compounds. 5-Phenyltetrazole was also transformed under the above conditions into a series of aryl-1,3,4-oxadiazolyl-1,2,3-triazoles, aryl-1,2,3-triazolyl-1,3,4-oxadiazoles, and aryl-1,3,4-oxadiazolylmethyl-1,2,3-triazoles. The new compounds were assayed against rabbit muscle glycogen phosphorylase b and the best inhibitors had inhibition constants in the upper micromolar range (2-phenyl-5-[1-(β-D-glucopyranosyl)-1,2,3-triazol-4-yl]-1,3,4-oxadiazole 36: K(i)=854μM, 2-(β-D-glucopyranosyl)-5-[1-(naphthalen-2-yl)-1,2,3-triazol-4-yl]-1,3,4-oxadiazole 47: K(i)=745μM).     

Fungistatic Intensity of Agricultural Soil Against Fungal Agents and Phylogenetic Analysis on the Actinobacteria Involved

A total of 287 agricultural soil samples collected from 26 provinces or autonomous regions of China were tested on their ability to suppress the conidial germination of nine biocontrol fungal agents. These soil samples showed great differences in the degree to inhibit the germination of conidia (22.8% < mean inhibition rate < 97.5%), but all exhibited fungistatic activities above the moderate levels (mean inhibition rate > 50%) to most of tested fungi. Ten soil samples that have stronger fungistatic intensity (germination inhibition rate > 68.3%) to the target fungi, Trichoderma viride and Paecilomyces lilacinus, were selected to evaluate their soil actinobacteria involved fungistasis in soil. Of the 1,000 isolates from those soil samples, 345 actinobacteria exhibited fungistatic activity to conidial germination of T. viride and P. lilacinus with germination inhibition rates higher than 10%. Sequences encoding 16S rRNA gene of the 345 actinobacteria were analyzed by ARDRA and resulted 44 different ARDRA types. Fifty-six isolates, at least one from each unique ARDRA type, were selected for 16S rDNA sequencing and phylogenetic analysis. Results indicated that the actinobacteria involved in the soil fungistasis had close phylogenetic relationship with the members of Sterptomycetaceae, Microbacteriaceae, Micrococcaceae, and Nocardiacea.     

Effects of a moderate-intensity static magnetic field and adriamycin on K562 cells

The aim of this study was to investigate whether a moderate‐intensity static magnetic field (SMF) can enhance the killing effect of adriamycin (ADM) on K562 cells, and to explore the effects of SMF combined with ADM on K562 cells. We analyzed the metabolic activity of cells, cell cycle distribution, DNA damage, change in cell ultrastructure, and P‐glycoprotein (P‐gp) expression after K562 cells were exposed continuously to a uniform 8.8 mT SMF for 12 h, with or without ADM. Our results showed that the SMF combined with ADM (25 ng/ml) significantly inhibited the metabolic activity of K562 cells (P < 0.05), while neither ADM nor the SMF alone affected the metabolic activity of these cells. Cell ultrastructure was altered in the SMF + ADM group. For example, cell membrane was depressed, some protuberances were observable, and vacuoles in the cytoplasm became larger. Cells were arrested at the G2/M phase and DNA damage increased after cells were treated with the SMF plus ADM. ADM also induced the P‐gp expression. In contrast, in the SMF group and SMF + ADM group, the P‐gp expression was decreased compared with the ADM group. Taken together, our results showed that the 8.8 mT SMF enhanced the cytotoxity potency of ADM on K562 cells, and the decrease in P‐gp expression may be one reason underlying this effect. Bioelectromagnetics 32:191–199, 2011. © 2010 Wiley‐Liss, Inc.     

一肾一包型高血压大鼠动脉压力反射敏感性的变化

本文用苯肾上腺素和硝普钠改变血压,同步记录心动周期,用平均动脉血压-心动周期关系为指标,研究了 Grollman一肾一包型肾性高血压大鼠动脉压力感受性反射敏感性(Ar-terial baroreflex sensitivity,ABS)的变化。实验分为三组:Grollman 高血压组,假手术组和正常组,手术后三周进行实验,结果如下:Grollman 高血压组的 ABS 明显低于假手术组(P<0.01);侧脑室注射150μg Captopril 后,Grollman 高血压组和假手术组的 MAP都下降,但 Grollman 组更明显(注射35 min 时,P<0.01 Fig.1),注射后35到60 min时,假手术组的 MAP 已趋稳定水平,而 Grollman 组仍有下降趋势。注射后60 min 时高血压组的 ABS 比注射前60 min 值明显增加,而假手术组的增加不明显(Fig.2)。此外向正常动物 i.v.c.注射8μg 血管紧张素Ⅱ,MAP 显著增加但 ABS 则显著下降。上述结果提示在Grollman 肾性高血压形成期,ABS 下降,这可能与中枢血管紧张素Ⅱ含量的增加有关。     

Landscape patterns and their changes in Sichuan Ruoergai Wetland National Nature Reserve

In Sichuan Ruoergai Wetland National Nature Reserve, the changes in landscape patterns over a period of 17 years – from 1990 to 2007 – have been studied by means of RS, GIS technologies and field validation. In the reserve, the seven landscape patterns – river, lake, swamp, seasonal swamp, meadow, shrub and desert – were subject to the current study. The results show that the swamp, seasonal swamp, and meadow are the dominant landscape types occupying over 90% of the reserve’s total area. Over the past 17 years, the distribution area of swamp has been decreased by 3.81%, while that of seasonal swamp and meadow has been increased by 2.58% and 2.09%, respectively. In addition, the desert area has expanded by 1.19% since 2000. The nature reserve can be characterized by patch diversity, causing landscape fragmentation over the years; the total number of patches increased to 585 from 544 and the average area of the patches decreased to 283.49 h m² from 304.29 h m² – to the detriment of the wetland functions such as carbon sink and habitats for wild animals. In the study, the causes of the alternations are discussed as mainly resulting from climate change and human disturbances such as overgrazing, drainage, and unmanaged tourism. The study results provide a scientific basis at a strategic scale for the efficient conservation and management implementation of nature reserve zoning and assessment of landscape ecological functions and conservation values.     

Molecular cloning and expression of nitric oxide synthase gene in chick embryonic muscle cells

The chick skeletal muscle nitric oxide synthase (NOS) gene was cloned in order to further define the involvement of NOS in the differentiation of skeletal muscle cells. The respective cDNA had an open reading frame of 1136 amino acid residues, predicting a protein of 129,709.85 Da, and recognition sites for FAD, FMN, NADPH, and a calmodulin-binding site like those of other mammalian NOS's. Alignment of the deduced amino acid sequence revealed high homology with mammalian inducible NOS (iNOS), but not other NOS isoforms, suggesting chick skeletal muscle NOS may be an iNOS isoform. Immunoblots showed that NOS expression was highly restricted in embryonic muscle, but not in adult skeletal muscle: NOS expression markedly increased from embryonic day 9, reached a maximum by embryonic day 13, and then gradually declined until it was no longer detectable on embryonic day 19. When muscle cells obtained on embryonic day 12 were cultured, NOS expression increased transiently prior to the onset of differentiation and decreased thereafter. Inhibition of NOS expression by PDTC completely prevented muscle cell differentiation, as indicated by the inhibition of expression of myosin heavy chain and creatine kinase. The inhibitory effect of PDTC was completely reversed by addition of sodium nitroprusside, a compound that produces NO. These results clearly indicate that NOS is significantly involved in the differentiation of chick skeletal muscle cells.     

Coenzymatic activity of randomly broken or intact double-stranded DNAs in auto and histone H1 trans-poly(ADP-ribosylation), catalyzed by poly(ADP-ribose) polymerase (PARP I)

The enzymatic transfer of ADP-ribose from NAD to histone H1 (defined as trans-poly(ADP-ribosylation)) or to PARP I (defined as auto-poly(ADP-ribosylation)) was studied with respect to the nature of the DNA required as a coenzyme. Linear double-stranded DNA (dsDNA) containing the MCAT core motif was compared with DNA containing random nicks (discontinuous or dcDNA). The dsDNAs activated trans-poly(ADP-ribosylation) about 5 times more effectively than dcDNA as measured by V(max). Activation of auto-poly(ADP-ribosylation) by dcDNA was 10 times greater than by dsDNA. The affinity of PARP I toward dcDNA or dsDNA in the auto-poly(ADP-ribosylation) was at least 100-fold lower than in trans-poly(ADP-ribosylation) (K(a) = 1400 versus 3-15, respectively). Mg2+ inhibited trans-poly(ADP-ribosylation) and so did dcDNA at concentrations required to maximally activate auto-poly(ADP-ribosylation). Mg2+ activated auto-poly(ADP-ribosylation) of PARP I. These results for the first time demonstrate that physiologically occurring dsDNAs can serve as coenzymes for PARP I and catalyze preferentially trans-poly(ADP- ribosylation), thereby opening the possibility to study the physiologic function of PARP I.