Improvement of pristinamycin production by genome shuffling and medium optimization for Streptomyces pristinaespiralis

To isolate an improved pristinamycin producing strain of Streptomyces pristinaespiralis, the technique of Genome shuffling was used which resulted in a high-yield recombinant G 3-56 strain. Strain G 3-56 yielded 322 ± 17 mg/L of pristinamycin which was 11.4-fold higher than that of the initial strain and 3.7-fold higher than strain UN-78 which previously had the highest yield of pristinamycin. The genetic characteristics of the recombinant G 3-56 strain was stable as revealed by our subculture experiments. The optimal production medium was determined using the orthogonal matrix method. Under the optimal medium conditions, the maximum yield of pristinamycin was 412 mg/L with about 1.24-fold higher than the original medium.     

野油菜黄单胞菌分泌组双向电泳样品制备方法的建立

野油菜黄单胞菌野油菜致病变种(Xanthomonas campestris pv.campestris,Xcc)是十字花科植物黑腐病的病原细菌。我们建立了Xcc的蛋白质组学研究平台,用于分离、鉴定该菌的致病相关蛋白。为了减少胞外多糖(exopolysaccharide,EPS)对蛋白材料质量的影响,我们构建了EPS缺陷的Xcc8004ΔgumB突变体。本研究以Xcc8004ΔgumB出发菌株,用诱导培养液培养,取细胞上清通过超滤浓缩得到蛋白质粗提物,分别采用丙酮沉淀法、试剂盒纯化法和丙酮沉淀-试剂盒联用法来纯化蛋白质粗提物,通过比较双向电泳的结果优选最佳的样品制备方法。结果证明丙酮沉淀-试剂盒联用法较为理想,所得双向电泳图片清晰,分辨率高。因此,此方法可以用于制备野油菜黄单胞菌分泌组双向电泳样品,并可以满足进一步研究的需要。     

Cloning and expression of a pivotal calcium metabolism regulator: calmodulin involved in shell formation from pearl oyster (Pinctada fucata)

The shells of bivalves are mainly composed of calcium carbonate, a product of calcium metabolism. In the process of shell formation, the uptake, transport and recruitment of calcium ion are highly regulated and involved in many factors. Among these regulatory factors, calmodulin (CaM), a pivotal multifunction regulator of calcium metabolism in nearly all organisms, is thought to play an important role in the calcium metabolism involved in shell formation. In this study, a full-length CaM cDNA was isolated from the pearl oyster (Pinctada fucata). The oyster calmodulin encodes a 16.8 kDa protein which shares high similarity with vertebrate calmodulin. The oyster CaM mRNA shows the highest level of expression in the gill, a key organ involved in calcium uptake in oyster calcium metabolism. In situ hybridization results revealed that oyster CaM mRNA is expressed at the folds and the outer epithelial cells of the dorsal region of the mantle, suggesting that CaM is involved in regulation of calcium transport and secretion. Oyster CaM also showed a typical Ca2+ dependent electrophoretic shift characterization and calcium binding activity. Taken together, we have identified and characterized a pivotal calcium metabolism regulator of the oyster that may play an important role in regulation of calcium uptake, transport and secretion in the process of shell formation.     

High-level expression of soluble human β-defensin-2 in Escherichia coli

Human β-defensin-2 (hBD2) is a short cationic peptide with a broad antimicrobial spectrum. The coding sequence of hBD2 was cloned into pET-32a (+) to construct a fusion expression plasmid, pET32–hBD2, which was transformed into E. coli BL21 (DE3) for expression. The cultivation parameters of the expression vector harboring strain were optimized to produce the fusion protein in soluble form efficiently and to avoid the formation of insoluble inclusion bodies. The optimal conditions were determined as following: cultivation at 28 °C in MBL medium, induction at middle stage of exponential growth with 0.8 mM IPTG, and post-induction expression for 8 h. Under the above conditions, a high percentage of the target fusion protein (≥92.3%) was expressed in soluble form and the volumetric productivity of soluble fusion protein reached 1.3 g/l. The culture process was successfully scaled up in a 10 l bench-top fermentor.     

中国菊属一些种的分支分类学研究

运用分支分析方法研究了12种原产中国的野生菊属植物的系统发育关系,并引入了若干栽培品种及部分杂种一代植株作为分析材料。研究结果表明：分支分析方法有效而准确地将分类群分类,并揭示出毛华菊（Dendranthemarestitum）与菊花（Dendranthema×gran-diflorum）同为菊属植物中进化程度较高的种,部分种间杂种也已进入栽培类群。同时还发现不同性状在各品种间平行进化的现象。根据上述结果,作者讨论了中国菊属植物的系统进化及菊花起源问题。     

ScrepYard: An online resource for disulfide‐stabilized tandem repeat peptides

Receptor avidity through multivalency is a highly sought‐after property of ligands. While readily available in nature in the form of bivalent antibodies, this property remains challenging to engineer in synthetic molecules. The discovery of several bivalent venom peptides containing two homologous and independently folded domains (in a tandem repeat arrangement) has provided a unique opportunity to better understand the underpinning design of multivalency in multimeric biomolecules, as well as how naturally occurring multivalent ligands can be identified. In previous work, we classified these molecules as a larger class termed secreted cysteine‐rich repeat‐proteins (SCREPs). Here, we present an online resource; ScrepYard, designed to assist researchers in identification of SCREP sequences of interest and to aid in characterizing this emerging class of biomolecules. Analysis of sequences within the ScrepYard reveals that two‐domain tandem repeats constitute the most abundant SCREP domain architecture, while the interdomain “linker” regions connecting the functional domains are found to be abundant in amino acids with short or polar sidechains and contain an unusually high abundance of proline residues. Finally, we demonstrate the utility of ScrepYard as a virtual screening tool for discovery of putatively multivalent peptides, by using it as a resource to identify a previously uncharacterized serine protease inhibitor and confirm its predicted activity using an enzyme assay.     

基于肠道微生物组学分析不同比例肠内营养制剂对神经外科重症患者肠道功能、免疫功能的影响

使用肠道微生物组学技术探讨不同比例的肠内营养制剂对于神经外科重症患者肠道功能与免疫功能的影响。

选取2022年7月至2023年6月在我院进行治疗的神经外科重症患者,随机分为观察组、对照组,每组60例。对照组使用2/3标准剂量,观察组使用1/3标准剂量,对比两组患者的营养指标、免疫功能指标、粪便菌群alpha多样性、7 d内血糖水平、胰岛素的使用总量及并发症的发生情况。

在进行治疗后,观察组的总蛋白、白蛋白、前白蛋白及血红蛋白指标均显著高于对照组,差异均有统计学意义（均P＜0.05）;观察组患者的IL-6、IL-10及IL-17指标均显著低于对照组,差异均有统计学意义（均P＜0.05）;观察组患者粪便菌群中的Ace指数、Chao1指数、Shannon指数均显著高于对照组,Simpson指数显著低于对照组,差异均有统计学意义（均P＜0.05）;观察组血糖＞10.0 mmol/L的次数和胰岛素使用总量显著低于对照组,差异均有统计学意义（均P＜0.05）;两组患者在治疗时没有出现比较严重的并发症,观察组发生并发症人数显著低于对照组,差异有统计学意义（χ² = 3.927,P = 0.048）。

对于神经外科重症患者使用1/3标准剂量的营养支持能够改善患者的肠道功能和免疫指标,值得在临床中推广。

     

不同耐性水稻幼苗根系对镉胁迫的形态及生理响应

采用水培试验,以两个耐镉性不同的水稻品种为材料,研究了不同浓度镉胁迫对水稻幼苗根系形态、根系活力、游离脯氨酸含量及抗氧化酶活性的影响。结果表明:低于5 μmol/L Cd胁迫对2个水稻品种总根长、根表面积、根体积、根干重、根系活力无明显影响,在1 μmol/L Cd时,甚至起促进作用。随Cd浓度增加表现出一定的抑制效应,秀水63在10 μmol/L Cd胁迫下根系形态、根系活力明显受到抑制,而秀水09在25 μmol/L Cd胁迫下明显受抑。随Cd胁迫浓度的增加,游离脯氨酸含量、丙二醛(MDA)含量、超氧化物歧化酶(SOD)、过氧化物酶(POD)活性均呈上升趋势,两品种相比,秀水09的游离脯氨酸含量、SOD和POD增幅大于秀水63,而MDA含量增幅小于秀水63;过氧化氢酶(CAT)活性变化表现为先上升后下降,10-100 μmol/L Cd胁迫下秀水63根系中CAT活性明显低于秀水09。总之,水稻对Cd毒害响应存在明显的品种差异,且Cd胁迫下根系生理响应的差异是品种间耐性差异的重要原因之一。     

Gualou Xiebai Banxia decoction ameliorates Poloxamer 407-induced hyperlipidemia

Ethnopharmacological relevance: Gualou Xiebai Banxia (GLXBBX) decoction is a well-known traditional Chinese herbal formula that was first discussed in the Synopsis of the Golden Chamber by Zhang Zhongjing in the Eastern Han Dynasty. In traditional Chinese medicine, GLXBBX is commonly prescribed to treat cardiovascular diseases, such as coronary heart disease and atherosclerosis.Objective: The present study aimed to examine GLXBBX’s preventative capacity and elucidate the potential molecular mechanism of Poloxamer 407 (P407)-induced hyperlipidemia in rats.Materials and methods: Both the control and model groups received pure water, and the test group also received a GLXBBX decoction. For each administration, 3 ml of the solution was administered orally. To establish hyperlipidemia, a solution mixed with 0.25 g/kg P407 dissolved in 0.9% normal saline was injected slowly into the abdominal cavity. At the end of the study, the rats’ plasma lipid levels were calculated using an automatic biochemical analyzer to evaluate the preventative capability of the GLXBBX decoction, and the serum and liver of the rats were collected.Results: The GLXBBX decoction significantly improved P407-induced hyperlipidemia, including increased plasma triglycerides (TGs), aspartate aminotransferase (AST) elevation, and lipid accumulation. Moreover, GLXBBX decoction treatment increased lipoprotein lipase (LPL) activity and mRNA expression of LPL. Furthermore, GLXBBX significantly suppressed the mRNA expression of stearoyl-CoA desaturase (SCD1).Conclusion: GLXBBX significantly improved P407-induced hyperlipidemia, which may have been related to enhanced LPL activity, increased LPL mRNA expression, and decreased mRNA expression of SCD1.