基于肠道微生态改善的益生菌抗糖尿病作用机制研究进展

2型糖尿病(type 2 diabetes, T2D)会引起糖脂代谢紊乱,严重危害人类健康,为了防治这一流行病,急需寻找安全和无副作用的抗糖尿病的方法,其中,基于微生物方法治疗T2D最常见的策略是补充益生菌,其可通过对不同组织和代谢通路的调节来实现抗糖尿病的功效。益生菌摄入可通过降低慢性低度炎症,减少氧化应激,调节肠道菌群,增加短链脂肪酸含量来达到调控血糖的目的;通过增加胆固醇与胆盐的共沉淀作用,胆固醇在胃肠道内转化为粪甾醇,降低肝脏中3-羟基-3-甲基戊二酸单酰辅酶A还原酶活性,降低胆固醇转运体的表达及对脂肪细胞的调节来达到降脂的目的。本综述系统总结了益生菌抗糖尿病现状和基于肠道微生态的抗糖尿病分子机制,以期为益生菌作为降糖降脂等保健产品的开发利用提供理论依据。     

鸦胆子抗肿瘤活性成分的化学研究

从苦木科植物鸦胆子[Brucea javanica(L.)Merr]干躁果实的硅胶干柱柱层析所得的活性部位中经层析分离得到7个四环三萜苦木内酯成份(A,B,C,D,E,F,G),经UV,IR,~1H-NMR,~(13)C-NMR等方法鉴定分别为鸦胆苦醇(Brusatol A),双氢鸦胆苦醇(Dihydrobrusatol,B),鸦胆因B(Bruceine B,C),鸦胆因D(Bruceine D,D),鸦胆因H(Bruceine H,E),鸦胆子甙A(Bruceoside A,F)和双氢鸦胆子甙A(Yadanzioside A,G)。据报道,鸦胆苦醇和鸦胆子甙A具有较强的抗肿瘤活性。     

Effect of leaf water extracts of four Asteraceae alien invasive plants on germination performance of Lactuca sativa L. under acid deposition

Plant Ecology - Allelopathy of alien invasive plants (AIP) on plant germination performance is essential for their successful invasion. However, the allelopathy of AIP may be reformed or even...     

Lactobacillus paracasei subsp. paracasei LC01 positively modulates intestinal microflora in healthy young adults

Lactobacillus paracasei subsp. paracasei LC01 (LC01) can tolerate intestinal stresses and has antioxidant activity. To evaluate the effect of the bacterium on human intestinal microflora, a randomized, double-blind, placebo-controlled human trial was carried out. Fifty-two healthy adult volunteers were randomized equally to two groups. One group consumed 12% (wt/vol) skimmed milk supplemented with 10¹⁰ CFU of LC01 each day for the 4-week treatment period, and then consumed placebo in the next treatment period, separated by a 2-week washout. The other group followed the reverse order. Group-specific real-time PCR and biochemical analyses was used to determine the intestinal bacterial composition of fecal samples collected at the end of every period, and the concentration of short-chain fatty acids and ammonia. A significant inhibition in fecal Escherichia coli and increase in Lactobacillus, Bifidobacterium, and Roseburia intestinalis were observed after consumption of LC01. Acetic acid and butyric acid were significantly higher in the probiotic stage and fecal ammonia was significantly lower. The results indicated a modulation effect of LC01 on the intestinal microflora of young adults, suggesting a beneficial effect on bowel health. LC01 may have potential value as a probiotic.     

Synthesis and in vitro antibacterial activity of quinolone/naphthyridone derivatives containing 3-alkoxyimino-4-(methyl)aminopiperidine scaffolds

We report herein the synthesis of a series of 7-[3-alkoxyimino-4-(methyl)aminopiperidin-1-yl]quinolone/naphthyridone derivatives. In vitro antibacterial activity of these derivatives was evaluated against representative strains, and compared with ciprofloxacin (CPFX), levofloxacin (LVFX) and gemifloxacin (GMFX). The results reveal that all of the target compounds 19a–c and 20 have considerable Gram-positive activity, although they are generally less active than the reference drugs against the Gram-negative strains with some exceptions. Especially, novel compounds 19a2, 19a4 and 19a5 were found to show strong antibacterial activity (MICs: <0.008–0.5 μg/mL) against all of the tested 15 Gram-positive strains including MRSA, LVFX- and GMFX-resistant MRSE, and CPFX-, LVFX- and GMFX-resistant MSSA.     

A barley stripe mosaic virus-based guide RNA delivery system for targeted mutagenesis in wheat and maize

Plant RNA virus-based guide RNA (gRNA) delivery has substantial advantages compared to that of the conventional constitutive promoter-driven expression due to the rapid and robust amplification of gRNAs during virus replication and movement. To date, virus-induced genome editing tools have not been developed for wheat and maize. In this study, we engineered a barley stripe mosaic virus (BSMV)-based gRNA delivery system for clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9-mediated targeted mutagenesis in wheat and maize. BSMV-based delivery of single gRNAs for targeted mutagenesis was first validated in Nicotiana benthamiana. To extend this work, we transformed wheat and maize with the Cas9 nuclease gene and selected the wheat TaGASR7 and maize ZmTMS5 genes as targets to assess the feasibility and efficiency of BSMV-mediated mutagenesis. Positive targeted mutagenesis of the TaGASR7 and ZmTMS5 genes was achieved for wheat and maize with efficiencies of up to 78% and 48%. Our results provide a useful tool for fast and efficient delivery of gRNAs into economically important crops.     

Drought may be beneficial to the competitive advantage of Amaranthus spinosus

干旱利于刺苋的竞争优势 干旱可以影响入侵植物的生长和土壤酶活性。因此,非常有必要评估干旱背景下入侵植物的竞争优势以及入侵植物和干旱对土壤酶活性的影响。本研究旨在分析干旱背景下起源于热带美洲的入侵植物刺苋(Amaranthus spinosus)与本地植物苋菜(Amaranthus tricolor)共存时的竞争优势和土壤酶活性。通过栽植实验进行刺苋与苋菜的竞争共栽培,并进行不同水平的干旱处理,即：(i)对照;(ii)轻度干旱;(iii)重度干旱。实验结束后测定两种苋属植物的功能性状、渗透调节、抗氧化酶活性以及土壤pH、电导率、土壤微生物生物量碳含量和土壤酶活性。干旱背景下,刺苋的相对竞争强度和相对优势度均高于苋菜。因此,干旱利于刺苋的竞争优势。干旱背景下,刺苋的土壤水溶性盐含量和蔗糖水解能力均大于苋菜。而较高的土壤水溶性盐含量和蔗糖水解能力利于刺苋对养分的获取和利用。     

植物子平台及中国数字植物标本馆(CVH)运维: 做法和经验

该文系统介绍了植物子平台所采取的以数字标本质量为导向的数字化技术规范和管理策略,以及CVH网站数据共享规则, 并指出存在的问题及今后努力方向。     

卫矛科沟瓣属与卫矛属的数量分类学研究

卫矛属(Euonymus L.)和沟瓣属(Glyptopetalum Thw.)的系统关系长期以来备受争议,为理清它们之间的关系,该研究选择沟瓣属12种、卫矛属17种和假卫矛属(Microtropis Wall.ex Meisn.)2种,共计31个分类单元(OTUs),测量并统计了56个形态性状,同时利用聚类分析(UP...     

Effect of Pre-Stressing on the Acid-Stress Response in Bifidobacterium Revealed Using Proteomic and Physiological Approaches

Weak acid resistance limits the application of Bifidobacteria as a probiotic in food. The acid tolerance response (ATR), caused by pre-stressing cells at a sublethal pH, could improve the acid resistance of Bifidobacteria to subsequent acid stress. In this study, we used Bifidobacterium longum sub. longum BBMN68 to investigate the effect of the ATR on the acid stress response (ASR), and compared the difference between the ATR and the ASR by analyzing the two-dimensional-PAGE protein profiles and performing physiological tests. The results revealed that a greater abundance of proteins involved in carbohydrate metabolism and protein protection was present after the ASR than after the ATR in Bifidobacterium. Pre-stressing cells increased the abundance of proteins involved in energy production, amino acid metabolism, and peptidoglycan synthesis during the ASR of Bifidobacterium. Moreover, after the ASR, the content of ATP, NH₃, thiols, and peptidoglycan, the activity of H⁺-ATPase, and the maintenance of the intracellular pH in the pre-stressed Bifidobacterium cells was significantly higher than in the uninduced cells. These results provide the first explanation as to why the resistance of Bifidobacterium to acid stress improved after pre-stressing.