催产素在脊髓水平对电针镇痛的影响

采用玻璃微电极胞外记录和脊髓表面给药的方法观察了催产素（ＯＴ）、抗催产素血清（ＡＯＴＳ）以及电针穴位对背角神经元伤害性诱发放电的影响。结果表明：电针穴位或脊髓表面施加ＯＴ可部分抑制脊髓背角神经元的伤害性诱发放电;在电针的基础上施加ＯＴ则明显加强电针的抑制效应;相反,用ＡＯＴＳ预处理后,电针的抑制作用放取消。提示ＯＴ在脊髓水平参与了对痛觉信息的调制,并与一定频率的针刺镇痛有关。     

Bovine serum albumin: characterization of a fatty acid binding site on the N-terminal peptic fragment using a new spin-label

A new spin-label, 4-(L-glutamo)-4'-[(1-oxy-2,2,5,5-tetramethyl-3L-pyrrolidinyl )amino]-3, 3'-dinitrodiphenyl sulfone, is shown to bind to one high-affinity binding site on bovine serum albumin (K = 5 X 10(4) M-1, n = 1). Analysis of the binding of the spin-label to the amino-terminal half (peptic fragment PB) and the carboxy-terminal half (peptic fragment PA) of BSA, and their complex (PA-PB), indicates that the spin-label binds to a long-chain fatty acid binding site located on PB. The usefulness of the novel specificity of the spin-label in characterizing this binding site is discussed.     

8—MOP对体外培养人癌细胞的光敏灭活作用

本文根据MTT只能被活的增殖细胞中线粒体切断形成紫色甲(?)的原理,测定了8—甲氧基补骨脂素(8—MOP)对体外培养人癌细胞系HCT、KB和BEL细胞的光敏灭活作用。结果表明,8—MOP和UVA光照对这几种人癌细胞有肯定的灭活作用,该作用与8—MOP剂量和光照时间以及细胞种类有关;MTT法可以作为光敏剂活性检测的一种快捷方法。     

The contrasting role of male relatedness in different mechanisms of sexual selection in red junglefowl

In structured populations, competition for reproductive opportunities should be relaxed among related males. The few tests of this prediction often neglect the fact that sexual selection acts through multiple mechanisms, both before and after mating. We performed experiments to study the role of within‐group male relatedness across pre‐ and postcopulatory mechanisms of sexual selection in social groups of red junglefowl, Gallus gallus, in which two related males and one unrelated male competed over females unrelated to all the males. We confirm theoretical expectations that, after controlling for male social status, competition over mating was reduced among related males. However, this effect was contrasted by other sexual selection mechanisms. First, females biased male mating in favor of the unrelated male, and might also favor his inseminations after mating. Second, males invested more—rather than fewer—sperm in postcopulatory competition with relatives. A number of factors may contribute to explain this counterintuitive pattern of sperm allocation, including trade‐offs between male investment in pre‐ versus postcopulatory competition, differences in the relative relatedness of pre‐ versus postcopulatory competitors, and female bias in sperm utilization in response to male relatedness. Collectively, these results reveal that within‐group male relatedness may have contrasting effects in different mechanisms of sexual selection.     

Surface display of ACC deaminase on endophytic <Emphasis Type="Italic">Enterobacteriaceae</Emphasis> strains to increase saline resistance of host rice sprouts by regulating plant ethylene synthesis

Background

Most endophytic bacteria in consortia, which provide robust and broad metabolic capacity, are attractive for applications in plant metabolic engineering. The aim of this study was to investigate the effects of engineered endophytic bacterial strains on rice sprout ethylene level and growth under saline stress. A protocol was developed to synthesize engineered strains by expressing bacterial 1-aminocyclopropane-1-carboxylate (ACC) deaminase gene on cells of endophytic Enterobacter sp. E5 and Kosakonia sp. S1 (denoted as E5P and S1P, respectively).

Results

Results showed that ACC deaminase activities of the engineered strains E5P and S1P were significantly higher than those of the wild strains E5 and S1. About 32–41% deaminase was expressed on the surface of the engineered strains. Compared with the controls without inoculation, inoculation with the wild and engineered strains increased the deaminase activities of sprouts. Inoculation with the engineered strains increased 15–21% more deaminase activities of sprouts than with the wild strains, and reduced the ethylene concentrations of sprouts more significantly than with wild strains (P < 0.05). Inoculation with the wild and engineered strains promoted the growth of sprouts, while the promoting effects were more profound with the engineered strains than with the wild strains. The engineered strains improved saline resistance of sprouts under salt concentrations from 10 to 25 g L^?1. The engineered strains promoted longer roots and shoots than the wild strains under the salt stresses, indicating that the ACC deaminases on the endophytic bacterial cells could result in plant-produced ACC degradation and inhibit plant ethylene formation.

Conclusions

The protocols of expressing enzymes on endophytic bacterial cells showed greater potentials than those of plant over-expressed enzymes to increase the efficiency of plant metabolic pathways.

     

Distinguishing the effects of vegetation restoration on runoff and sediment generation on simulated rainfall on the hillslopes of the loess plateau of China

Aims

Since the 1970s, extensive croplands were converted to forest and pasture lands to control severe soil erosion on the Loess Plateau of China. We quantify the direct and indirect effects of vegetation restoration on runoff and sediment yield on hillslopes in the field to improve environmental governance.

Methods

An artificial rainfall experiment at a rainfall intensity of 120 mm h⁻¹ and a slope gradient of 22° were used to distinguish the effects of vegetation restoration on runoff and sediment yield.

Results

Compared to the farmland slopes, vegetation restoration directly prolonged the time-to-runoff by 140%, reduced the runoff rate by 20%, and increased the soil infiltration capacity by 15%. Vegetation restoration indirectly delayed the time-to-runoff by 120%, reduced the runoff rate and sediment yield rate by 50% and 94%, respectively, and increased the soil infiltration capacity by 58% on the hillslopes with vegetation restoration.

Conclusions

The direct effects of vegetation restoration on runoff and sediment yield were lower than its indirect impacts. Vegetation cover, decreases in soil bulk density, and increases in belowground root biomasses and > 0.25 mm aggregate stability were the primary causes of runoff and sediment yield reduction on the slopes with vegetation restoration.

     

microRNA-95 knockdown inhibits epithelial–mesenchymal transition and cancer stem cell phenotype in gastric cancer cells through MAPK pathway by upregulating DUSP5

This study investigated the role of microRNA-95 (miR-95) in gastric cancer (GC) and to elucidate the underlying mechanism. Initially, bioinformatic prediction was used to predict the differentially expressed genes and related miRNAs in GC. miR-95 and DUSP5 expression was altered in GC cell line (MGC803) to evaluate their respective effects on the epithelial–mesenchymal transition (EMT) process, cellular processes (cell proliferation, migration, invasion, cell cycle, and apoptosis), cancer stem cell (CSC) phenotype, as well as tumor growth ability. It was further predicted in bioinformatic prediction and verified in GC tissue and cell line experiments that miR-95 was highly expressed in GC. miR-95 negatively regulated DUSP5, which resulted in the MAPK pathway activation. Inhibited miR-95 or overexpressed DUSP5 was observed to inhibit the levels of CSC markers (CD133, CD44, ALDH1, and Lgr5), highlighting the inhibitory role in the CSC phenotype. More important, evidence was obtained demonstrating that miR-95 knockdown or DUSP5 upregulation exerted an inhibitory effect on the EMT process, cellular processes, and tumor growth. Together these results, miR-95 knockdown inhibited GC development via DUSP5-dependent MAPK pathway.     

Comparative evaluation of different cell disruption methods for the release of recombinant hepatitis B core antigen from <Emphasis Type="Italic">Escherichia coli</Emphasis>

A comparative evaluation of five different cell-disruption methods for the release of recombinant hepatitis B core antigen (HBcAg) from Escherichia coli was investigated. The cell disruption techniques evaluated in this study were high-pressure homogenization, batch-mode bead milling, continuous-recycling bead milling, ultrasonication, and enzymatic lysis. Continuous-recycling bead milling was found to be the most effective method in terms of operating cost and time. However, the highest degree of cell disruption and amounts of HBcAg were obtained from the high-pressure homogenization process. The direct purification of HBcAg from the unclarified cell disruptate derived from high-pressure homogenization and bead milling techniques, using batch anion-exchange adsorption methods, showed that the conditions of cell disruption have a substantial effect on subsequent protein recovery steps.     

Efficient expression of human soluble guanylate cyclase in Escherichia coli and its signaling-related interaction with nitric oxide

Soluble guanylate cyclase (sGC), as a nitric oxide (NO) sensor, is a critical heme-containing enzyme in NO-signaling pathway of eukaryotes. Human sGC is a heterodimeric hemoprotein, composed of a α-subunit (690 AA) and a heme-binding β-subunit (619 AA). Upon NO binding, sGC catalyzes the conversion of guanosine 5′-triphosphate (GTP) to 3′,5′-cyclic guanosine monophosphate (cGMP). cGMP is a second messenger and initiates the nitric oxide signaling, triggering vasodilatation, smooth muscle relaxation, platelet aggregation, and neuronal transmission etc. The breakthrough of the bottle neck problem for sGC-mediated NO singling was made in this study. The recombinant human sGC β1 subunit (HsGCβ619) and its truncated N-terminal fragments (HsGCβ195 and HsGCβ384) were efficiently expressed in Escherichia coli and purified successfully in quantities. The three proteins in different forms (ferric, ferrous, NO-bound, CO-bound) were characterized by UV–vis and EPR spectroscopy. The homology structure model of the human sGC heme domain was constructed, and the mechanism for NO binding to sGC was proposed. The EPR spectra showed a characteristic of five-coordinated heme-nitrosyl species with triplet hyperfine splitting of NO. The interaction between NO and sGC was investigated and the schematic mechanism was proposed. This study provides new insights into the structure and NO-binding of human sGC. Furthermore, the efficient expression system of E. coli will be beneficial to the further studies on structure and activation mechanism of human sGC.     

CCL5/CCR5 axis promotes the motility of human oral cancer cells

CCL5 (previously called RANTES) is in the CC‐chemokine family and plays a crucial role in the migration and metastasis of human cancer cells. On the other hand, the effect of CCL5 is mediated via CCR receptor. RT‐PCR and flow cytometry studies demonstrated CCR5 but not CCR1 and CCR3 mRNA in oral cancer cell lines, especially higher in those with high invasiveness (SCC4) as compared with lower levels in HSC3 cells and SCC9 cells. Stimulation of oral cancer cells with CCL5 directly increased the migration and metalloproteinase‐9 (MMP‐9) production. MMP‐9 small interfering RNA inhibited the CCL5‐induced MMP‐9 expression and thereby significantly inhibited the CCL5‐induced cell migration. Activations of phospholipase C (PLC), protein kinase Cδ (PKCδ), and NF‐κB pathways after CCL5 treatment was demonstrated, and CCL5‐induced expression of MMP‐9 and migration activity was inhibited by the specific inhibitor of PLC, PKCδ, and NF‐κB cascades. In addition, migration‐prone sublines demonstrate that cells with increasing migration ability had more expression of MMP‐9, CCL5, and CCR5. Taken together, these results indicate that CCL5/CCR5 axis enhanced migration of oral cancer cells through the increase of MMP‐9 production. J. Cell. Physiol. 220: 418–426, 2009. © 2009 Wiley‐Liss, Inc.