Enzymatic synthesis and antitumor evaluation of mono- and diesters of 3-O-β-D-galactopyranosyl-sn-glycerol

Lipase-catalyzed synthesis of mono- and diesters of 3-O-β-D-galactopyranosyl-sn- glycerol (β-GG) with caproic acid was performed in acetone. The simultaneous production of 1(6’)-monoesters and 1,6’-diesters of β-GG was achieved in this reaction. In order to improve the yield of β-GG esters, four process parameters, enzyme concentration (15?～?25?mg/mL), and substrate molar ratio (caproic acid: β-GG=?1.60?～?2.00?mmol: 0.10?mmol), reaction temperature (40?～?60?°C), and reaction time (8?～?12?h), were optimized via response surface methodology (RSM) employing a three-level-four-variable central composite design. Results showed that enzyme concentration had the most significant (p?β-GG esters. The optimal reaction conditions in acetone were given as follows: Novozyme435 concentration 18.65?mg/mL, molar rate of caproic acid to β-GG 19.46:1, reaction temperature 48?°C, and reaction time 9.83?h. The yield of β-GG esters reached 88.08% under above optimized conditions, which was very close to the predicted value 87.95%. The molar ratio of monoester to diesters was 0.39:0.61. β-GG esters with other fatty acyl chains were synthesized based on the optimized conditions. In vitro antitumor activity indicated that the antitumor activity of β-GG esters was dependent on the nature of fatty acids, such as the length of acyl chain, the degree of saturation, as well as the number of acyl chain.     

Assessing the conservation effectiveness of wetland protected areas in Northeast China

The evaluation of conservation effectiveness for wetland protected areas (WPAs) is essential to underpin knowledge-based conservation policies and funding decisions by government and managers. In this paper, the conservation effectiveness for 28 WPAs in Northeast China from 2000 to 2012 was quantitatively evaluated using landsat thematic mapper image data and a maximum entropy model (Maxent). The spatial distribution of conservation effectiveness and the influence of human activities on conservation effectiveness were determined by combining a landscape development intensity (LDI) index and spatial analysis in a geographical information system. The results showed that the natural wetland area of all WPAs in Northeast China declined by 11.5 % and the conservation effectiveness of most of these WPAs decreased between 2000 and 2012. A significant negative correlation between the LDI index and conservation effectiveness (r = ?0.824, p < 0.01) suggested that human activities were responsible for the low conservation effectiveness of WPAs. The WPAs with the high conservation effectiveness were mainly located in the Da-Xing’an and Xiao-Xing’an Mountains, where anthropogenic activities were limited. The reduction in the conservation effectiveness of WPAs in the Songnen and Sanjiang Plains, which showed the most degradation, was due to conversion of wetlands to croplands. This research offers an efficient and effective method to evaluate the conservation effectiveness of WPAs. The results of this study will inform future ecological conservation and management of WPAs in China.     

寡雄腐霉发酵液的动物安全性及其对黄瓜的防病促生效应

【目的】生物农药安全无害,环境友好。为了评价寡雄腐霉发酵液(Pythium oligandrum broth,POB)的动物安全性和防病促生效应,研制高效、无害的生物农药。【方法】试验利用自主分离的寡雄腐霉生防菌株(P.oligandrum CQ2010)制备POB,通过动物试验、拮抗试验、盆栽和生产试验,研究了POB的动物毒性,对黄瓜蔓枯病的防治作用,以及对黄瓜生长、产量和品质的影响。【结果】用大剂量的POB灌胃给药对小鼠体重增长无显著影响,其外观和行为均无异常,组织器官也未见病理改变。POB对甜瓜球腔菌的抑制率为51.95%,药效介于1∶800的百菌清溶液和1∶200的甲基托布津溶液之间。在黄瓜幼苗接种甜瓜球腔菌前后喷施POB,叶片丙二醛含量下降,过氧化物酶和超氧化物歧化酶活性增强,发病率和病情指数均显著降低,相对防治效果达到54.8%–64.1%,故POB能减轻病原菌对细胞膜的伤害,激发防御性生理反应,增强黄瓜植株的抗病能力。此外,POB处理提高叶绿素含量,增强根系活力,增加植株氮、磷、钾吸收量,促进黄瓜植株生长,生物量和果实产量分别提高81.10%和11.58%。POB还使黄瓜果实Vc和可溶性糖提高,硝酸盐含量降低。【结论】寡雄腐霉发酵液对动物安全无毒,能有效防治黄瓜蔓枯病,促进黄瓜生长,提高产量品质。     

Expression,purification and characterization of a vascular endothelial growth factor fusion protein

Objectives

To prepare recombinant tPep-(vascular endothelial growth factor) VEGF-B and assess its biological activity.

Results

This new VEGF fusion protein was constructed using a targeting peptide and prepared using E.coli. The tPep-VEGF-B was refolded from inclusion bodies and purified using affinity chromatography. Its bioactivity was determined in vitro using proliferation assay and wounding healing assay, and in vivo in zebrafish. By using the optimized downstream process, recombinant tPep-VEGF-B can be obtained with a purity of >90 % and a yield of 80 mg protein/l culture medium. The refolded protein is highly effective in promoting cell migration in vitro and in enhancing angiogenesis in vivo.

Conclusion

We have constructed a new VEGF fusion protein with potential therapeutic application in treating metabolic diseases.

     

Optimal secretion of alkali-tolerant xylanase in <Emphasis Type="Italic">Bacillus subtilis</Emphasis> by signal peptide screening

Xylanases are industrially important enzymes for xylan digestion. We experimentally screened over 114 Sec and 24 Tat pathway signal peptides, with two different promoters, for optimal production of an alkaline active xylanase (XynBYG) from Bacillus pumilus BYG in a Bacillus subtilis host. Though both promoters yielded highly consistent secretion levels (0.97 Pearson correlation coefficient), the Sec pathway was found to be more efficient than the Tat pathway for XynBYG secretion. Furthermore, the optimal signal peptide (phoB) for XynBYG secretion was found to be different from the optimal peptides for cutinase and esterase reported in previous studies. A partial least squares regression analysis further identified several statistically important variables: helical properties, amino acid composition bias, and the discrimination score in Signal P. These variables explain the observed 23 % variance in the secretion yield of XynBYG by the different signal peptides. The results also suggest that the helical propensity of a signal peptide plays a significant role in the beta-rich xylanase, but not in the helix-rich cutinase, suggesting a coupling of the conformations between the signal peptide and its cargo protein for optimal secretion.     

城乡交错带土壤氮素空间分布及其影响因素

城乡交错带土壤氮素是城乡生态系统中最重要的氮源与氮汇,但是城市化下的土壤氮素分布及其影响机制还不清楚,基于3S平台研究了土壤氮素在成都西郊城乡交错带的空间分布特征及城市化对土壤氮素的影响。结果表明,研究区内土壤全氮(STN)、硝态氮(NO_3~--N)和铵态氮(NH_4~+-N)含量均值分别为(1.46±0.06)g/kg、(50.04±3.59)mg/kg和(6.72±0.53)mg/kg。区内土壤氮素含量从近郊向远郊逐渐增高,STN和NO_3~--N含量为中部高于南北部,NH_4~+-N含量则由西北部和东南部向中部递增。方差分析表明,区内不同土地利用方式下STN、NO_3~--N和NH_4~+-N含量差异显著(P0.05)。回归分析显示STN含量与建筑密度(BD)、道路密度(RD)均呈现显著线性负相关(P0.05),NO_3~--N含量与道路密度呈极显著线性负相关(P=0.001),与建筑密度关系不明显(P=0.217)。土壤NH_4~+-N与建筑密度呈显著负线性相关(P=0.001),与道路密度呈显著指数相关关系(P=0.021)。研究结果显示城市发展使得城乡交错带土壤氮素含量降低,这种影响伴随着建筑面积的增加,道路长度的增加而加强。     

The N170 component is sensitive to face-like stimuli: a study of Chinese Peking opera makeup

The N170 component is considered a neural marker of face-sensitive processing. In the present study, the face-sensitive N170 component of event-related potentials (ERPs) was investigated with a modified oddball paradigm using a natural face (the standard stimulus), human- and animal-like makeup stimuli, scrambled control images that mixed human- and animal-like makeup pieces, and a grey control image. Nineteen participants were instructed to respond within 1000 ms by pressing the ‘F’ or ‘J’ key in response to the standard or deviant stimuli, respectively. We simultaneously recorded ERPs, response accuracy, and reaction times. The behavioral results showed that the main effect of stimulus type was significant for reaction time, whereas there were no significant differences in response accuracies among stimulus types. In relation to the ERPs, N170 amplitudes elicited by human-like makeup stimuli, animal-like makeup stimuli, scrambled control images, and a grey control image progressively decreased. A right hemisphere advantage was observed in the N170 amplitudes for human-like makeup stimuli, animal-like makeup stimuli, and scrambled control images but not for grey control image. These results indicate that the N170 component is sensitive to face-like stimuli and reflect configural processing in face recognition.     

Molecular Analysis of Atypical Family 18 Chitinase from Fujian Oyster Crassostrea angulata and Its Physiological Role in the Digestive System

Chitinolytic enzymes have an important physiological significance in immune and digestive systems in plants and animals, but chitinase has not been identified as having a role in the digestive system in molluscan. In our study, a novel chitinase homologue, named Ca-Chit, has been cloned and characterized as the oyster Crassostrea angulate. The 3998bp full-length cDNA of Ca-Chit consisted of 23bp 5-UTR, 3288 ORF and 688bp 3-UTR. The deduced amino acids sequence shares homologue with the chitinase of family 18. The molecular weight of the protein was predicted to be 119.389 kDa, with a pI of 6.74. The Ca-Chit protein was a modular enzyme composed of a glycosyl hydrolase family 18 domain, threonine-rich region profile and a putative membrane anchor domain. Gene expression profiles monitored by quantitative RT-PCR in different adult tissues showed that the mRNA of Ca-Chit expressed markedly higher visceral mass than any other tissues. The results of the whole mount in-situ hybridization displayed that Ca-Chit starts to express the visceral mass of D-veliger larvae and then the digestive gland forms a crystalline structure during larval development. Furthermore, the adult oysters challenged by starvation indicated that the Ca-Chit expression would be regulated by feed. All the observations made suggest that Ca-Chit plays an important role in the digestive system of the oyster, Crassostrea angulate.     

砾石对红壤工程堆积体边坡径流产沙的影响

为探究砾石对红壤工程堆积体边坡降雨侵蚀的影响,基于室内模拟降雨试验,在1.0、1.5、2.0、2.5 mm/min雨强条件下,以土质边坡为对照,研究了10%、20%和30%的砾石质量分数红壤工程堆积体边坡的径流特征、产沙过程及侵蚀动力机制。结果表明：1）砾石质量分数对稳定径流强度的影响存在阈值,在雨强 > 1.0 mm/min时稳定径流强度随砾石质量分数的增加先减小后增大,在1.0 mm/min雨强时则表现为先增大后减小,且均在10%砾石质量分数下达到极值;2）雨强1.0 mm/min时,径流为缓流,砾石促进径流流动,使弗汝德数增大24.5%-87.8%,雨强2.0、2.5 mm/min时,径流为急流,砾石延缓径流流动,使弗汝德数降低4.2%-13.0%;3）侵蚀速率随产流历时变化过程受砾石质量分数和雨强的影响,雨强越大,砾石质量分数越低,边坡越易发生细沟侵蚀且伴随重力崩塌现象,侵蚀速率呈多峰多谷变化趋势;4）1.0 mm/min雨强时,砾石存在加剧了土壤侵蚀,产沙增幅达28.7%-50.5%;雨强 > 1.0 mm/min时,砾石减沙效益为5.0%-64.4%;5）径流功率是描述红壤工程堆积体侵蚀动力机制最优参数,其可蚀性参数及发生侵蚀临界径流功率从大到小对应的砾石质量分数均为10%、0、20%和30%。研究成果可为红壤区开发建设项目水土流失治理及侵蚀预测模型提供科学依据。