Regulatory perspective of antibiotic biosynthesis in Streptomyces

<正>Streptomycetes are Gram-positive bacteria with high GC DNA content. They produce the most abundant secondary metabolites including over two-thirds of the clinically used antibiotics of natural origin (Barka et al., 2016), for example,the important broad-spectrum antimicrobials oxytetracycline(OTC) and chlortetracycline, which are the tetracycline antibiotics, produced by Streptomyces rimosus and Strepto-     

结合三代测序与二代测序技术揭示蜜蜂球囊菌孢子转录组的复杂性

【目的】蜜蜂球囊菌(Ascosphaera apis)是一种专性侵染蜜蜂幼虫的致死性真菌病原。本研究旨在利用PacBio单分子实时(singlemoleculereal-time,SMRT)测序技术对蜜蜂球囊菌孢子(AaS)中基因的可变剪切(alternative splicing,AS)和可变多聚腺苷酸化(alternative polyadenylation,APA)以及长链非编码RNA (long non-coding RNA,lncRNA)进行鉴定和分析,进而揭示蜜蜂球囊菌孢子中转录组的复杂性。【方法】采用Suppa软件对蜜蜂球囊菌孢子中基因的AS事件进行鉴定。通过RT-PCR对不同类型的AS事件进行验证。采用TAPIS pipeline对蜜蜂球囊菌孢子基因的APA位点进行鉴定。利用MEME软件分析孢子全长转录本的poly(A)剪接位点上游50bp的序列特征并鉴定motif。联用CPC和CNCI软件和比对Swiss-prot数据库的方法预测lncRNA,取三者的交集作为高可信度的lncRNA集合。进一步比较lncRNA和mRNA的转录本长度,外显子数量与长度,内含子长度,GC含...     

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.     

鸡减蛋综合征病毒(EDSV)基因组右末端结构的分析

从中国发病鸡中分离的鸡减蛋综合征病毒（ＥｇｇＤｒｏｐＳｙｎｄｒｏｍＶｉｒｕｓ,ＥＤＳＶ）弱毒株（ＡＡ－２）,其基因组全长约为３３ｋｂ。用限制性内切酶ＨｉｎｄⅢ水解ＥＤＳＶ全基因组,构建了以ｐＢｌｕｅｓｃｒｉｐｔⅡ（ＫＳ＋）为载体的右末端片段的克隆（约４．２ｋｂ）,对其进行了序列测定和结构分析。该片段全长４１８３个碱基对（ｂｐ）,位于基因组右末端８７．３ｍ．ｕ．－１００ｍ．ｕ．。结果显示,该片段与哺乳动物腺病毒右末端Ｅ４区结构不同,与禽Ⅰ型腺病毒代表株ＣＥＬＯ右末端片段亦无同源性。本文为深入了解ＥＤＳＶ基因组结构特点,ＥＤＳＶ与其他腺病毒基因结构与功能的进化关系和ＥＤＳＶ载体的构建奠定了分子生物学基础     

CTSB promotes porcine preadipocytes differentiation by degrading fibronectin and attenuating the Wnt/β-catenin signaling pathway

The process of preadipocytes differentiation plays a vital role in adipose tissue expansion and many factors are involved in this event. Cathepsin B (CTSB), secreted from lysosome, has been reported in regulating a variety of physiological processes. In this study, we demonstrated CTSB promotes lipid accumulation and adipogenic genes expression in porcine primary preadipocytes by degrading fibronectin (Fn), a key component of extracellular matrix. Lithium chloride (LiCl) is an activator of Wnt/β-catenin signaling through stabilizing β-catenin. We found that CTSB can relieve the anti-adipogenic effects of LiCl, indicating that CTSB could impact Wnt/β-catenin signaling pathway. Interestingly, Fn is an important target gene of Wnt/β-catenin. So we considered that CTSB promote preadipocytes differentiation by suppressing these two pathways.     

降解三硝基甲苯的酵母和类酵母菌的研究

从受三硝基甲苯（TNT）严重污染的土壤和废水中分离筛选到17株可降解TNT的酵母菌和白地霉。其中6株为克鲁斯假丝酵母（Candidakrusei）,4株为橡树假丝酵母（C.quercitrusa）,一株为无名假丝酵母（C.famata）,一株为伯杰汉逊酵母（Hansenulabeijerinckii）,一株为亚膜汉逊酵母（H.subpelliculosa）,4株为白地霉（Geotrichumcandidum）。对其中6株菌进行了降解TNT的条件实验,发现降解TNT的适宜pH为7,温度为37～40℃。在含75～80mg／LTNT的培养基中,40h内能降解TNT56～74mg／L,去除率达71％～93％。在培养基中加入0．01％～0．05％的葡萄糖作碳源,或加入0.01％～0．1％的酵母膏对6株菌降解TNT的能力略有促进作用。加入铵盐作为氮源则明显抑制这些菌对TNT的降解。     

薄层色谱-分光光度法测定樟芝菌粉中的总三萜含量

采用薄层色谱(TLC)-分光光度法测定樟芝菌粉中的总三萜含量.结果表明,适宜的展开剂组成为氯仿:甲醇＝9:1.该方法排除了樟芝菌粉中含有的脂肪等物质对测定总三萜含量的干扰,其准确度明显高于直接分光光度法和重量法,同时该方法具有较好的精密度,准确度及稳定性.     

Enhanced production of (+)-terrein in fed-batch cultivation of Aspergillus terreus strain PF26 with sodium citrate

(+)-Terrein is a fungal metabolite with multiple biological activities, especially with great value in medicine. However, the mass production of single configuration terrein is still a big challenge. In this study, the effects of acetic acid, sodium acetate, citric acid and sodium citrate on the (+)-terrein production by Aspergillus terreus strain PF26 derived from marine sponge Phakellia fusca were investigated. Sodium citrate was selected for fed-batch cultivation because it showed the best effect on (+)-terrein production among the four regulators tested. As a result, 5.38 g/L (+)-terrein production was achieved by feeding 10 mM sodium citrate on the 3rd day in shake flask, which was 33.8 % higher than the control and represented the highest yield of (+)-terrein. In a 7.5-L stirred bioreactor, 2.58 g/L of (+)-terrein production was achieved by the feeding of 10 mM sodium citrate on the 8th day. The results from this study lay a basis for the high-yield production of (+)-terrein by fermentation.     

Effect of TLR4/MyD88/NF‐kB axis in paraventricular nucleus on ventricular arrhythmias induced by sympathetic hyperexcitation in post‐myocardial infarction rats

Sympathetic activation after myocardial infarction (MI) leads to ventricular arrhythmias (VAs), which can result in sudden cardiac death (SCD). The toll‐like receptor 4 (TLR4)/myeloid differentiation primary response 88 (MyD88)/nuclear factor‐kappa B (NF‐kB) axis within the hypothalamic paraventricular nucleus (PVN), a cardiac‐neural sympathetic nerve centre, plays an important role in causing VAs. An MI rat model and a PVN‐TLR4 knockdown model were constructed. The levels of protein were detected by Western blotting and immunofluorescence, and localizations were visualized by multiple immunofluorescence staining. Central and peripheral sympathetic activation was visualized by immunohistochemistry for c‐fos protein, renal sympathetic nerve activity (RSNA) measurement, heart rate variability (HRV) analysis and norepinephrine (NE) level detection in serum and myocardial tissue measured by ELISA. The arrhythmia scores were measured by programmed electrical stimulation (PES), and cardiac function was detected by the pressure–volume loop (P‐V loop). The levels of TLR4 and MyD88 and the nuclear translocation of NF‐kB within the PVN were increased after MI, while sympathetic activation and arrhythmia scores were increased and cardiac function was decreased. However, inhibition of TLR4 significantly reversed these conditions. PVN‐mediated sympathetic activation via the TLR4/MyD88/NF‐kB axis ultimately leads to the development of VAs after MI.