Immunomodulatory effects of four polysaccharides purified from Erythronium sibiricum bulb on macrophages

Four neutral polysaccharides (ESBP1-1, ESBP1-2, ESBP2-1 and ESBP3-1) were successfully purified from the water extracted crude polysaccharides of Erythronium sibiricum bulbs through the combination of DEAE Sepharose CL-6B and Sephadex G-100 chromatography; their average molecular weights were 1.3?×?10⁴, 1.7?×?10⁴, 9.4?×?10⁵ and 4.1?×?10⁵ Da, respectively. Monosaccharide component analysis indicated that ESBP1-1 and ESBP1-2 were mainly composed of glucose (Glc). ESBP2-1 was composed of Glc, galactose (Gal) and arabinose, with a molar ratio of 24.3:1.1:1, whereas ESBP3-1 comprised Glc and Gal at a molar ratio of 14.8:1. In-vitro study showed that all of the four polysaccharides were able to considerably promote the proliferation and neutral red phagocytosis of RAW 264.7 macrophage cell. They could also stimulate the production of the cell lines’ secretory molecules [nitric oxide, tumour necrosis factor-α (TNF-α) and interleukin-1β (IL-1β)] in a dose-dependent manner. However, ESBP1-2 was not included in IL-1β. Overall, these results suggested that polysaccharides from E. sibiricum bulbs can be developed as immunomodulatory ingredients for complementary medicines or functional foods. However, further animal or clinical studies are required.

     

Isoflurane promotes proliferation of squamous cervical cancer cells through mTOR-histone deacetylase 6 pathway

Molecular and Cellular Biochemistry - This study investigated the effect of isoflurane on the proliferation of squamous cervical cancer cells, with focus on histone deacetylase 6 that is closely...     

黄土区不同恢复年限草地群落生物量及根冠比对氮添加的响应

大气氮沉降增加作为全球变化的主要环境问题之一,已引发人们的广泛关注,持续的氮沉降对草地生态系统的组成、结构和功能产生重要影响。为深入了解草地恢复进程中群落生物量和根冠比对氮沉降的响应,以黄土区3个不同恢复年限（初期12a、中期28a和后期37a）的天然草地为研究对象,通过设置6个氮添加水平,CK （0）、N1（2.34g m^-2a^-1）、N2（4.67g m^-2a^-1）、N3（9.34g m^-2a^-1）、N4（18.68g m^-2a^-1）、N5（37.35g m^-2a^-1）来测定草地群落地上生物量、地下生物量和总生物量,并计算根冠比和氮响应效率（NRE）。结果表明：（1）地上生物量在恢复中期最大,随氮添加梯度增加,地上生物量在恢复初期和恢复后期呈不显著上升趋势,对氮添加表现为非线性的正响应（ΔNRE>0）,在恢复中期呈不显著下降趋势,对氮添加表现为非线性的负响应（ΔNRE<0）。（2）群落地下生物量对氮添加无显著响应,总生物量只有在恢复后期的N4添加水平下,与对照存在显著差异。（3）根冠比在恢复初期时,N3添加水平下显著高于对照和其他氮添加水平,其余恢复年限对氮添加无显著响应。综上所述,通过分析比较黄土区不同恢复年限草地群落的地上、地下及总生物量和根冠比对氮添加的响应。建议对该区域开展试点实验,实行适应性草地管理,如进行两年一次刈割或轻度放牧（2只羊/hm²）,来探寻更科学有效的管理措施,使草地实现系统性恢复,进而满足生态系统容量和社会需求的变化。     

趋磁细菌及磁小体在肿瘤治疗中的应用

提高抗肿瘤药物的靶向性是肿瘤治疗、降低药物副作用的重要手段。在肿瘤组织内部由于癌细胞的快速增殖致使其形成低氧区,低氧区会对多种肿瘤治疗方案产生耐受。趋磁细菌 (Magnetotactic bacteria, MTB) 是一类能在细胞内产生外包生物膜、纳米尺寸、单磁畴磁铁矿 (Fe3O4) 或硫铁矿 (Fe3S4) 晶体颗粒-磁小体的微生物的统称。在磁场的作用下,趋磁细菌可凭借鞭毛运动至厌氧区。趋磁细菌在动物体内毒性较低且生物相容性良好,其磁小体与人工合成的磁性纳米材料相比优势显著。文中在介绍趋磁细菌及其磁小体生物学特点、理化性能的基础上,综述了趋磁细菌作为载体偶联药物进入肿瘤内部,并通过感受低氧信号定位于肿瘤低氧区,以及趋磁细菌竞争肿瘤细胞铁源的研究进展,总结了磁小体运载化疗药物、抗体、DNA疫苗靶向结合肿瘤的研究进展,分析了趋磁细菌及磁小体肿瘤治疗中面临的问题,并对趋磁细菌和磁小体在肿瘤治疗中的应用进行了展望。     

肠道菌群对耐碳青霉烯类肠杆菌科细菌定殖抗性的研究进展

耐碳青霉烯类肠杆菌科细菌(carbapenem-resistant Enterobacteriaceae,CRE)在肠腔中定殖通常先于或并存于CRE的感染。正常情况下,定殖的CRE、肠道菌群和宿主相互作用,处于稳定平衡的状态,当肠道菌群出现失调时,肠道正常菌群失去对定殖CRE的抵抗力,增加CRE感染的风险。大量研究表明通过肠道共生菌群对CRE的定殖抗性不仅可以预防感染,而且也可以降低医疗环境中患者间相互传播的风险。本文就CRE的流行现状、肠杆菌科细菌定殖机制以及肠道共生菌群对CRE定殖抗性机制作一综述,以期为CRE感染的防控工作提供新思路和新方法。     

SUMOylation stabilizes sister kinetochore biorientation to allow timely anaphase

During mitosis, sister chromatids attach to microtubules from opposite poles, called biorientation. Sister chromatid cohesion resists microtubule forces, generating tension, which provides the signal that biorientation has occurred. How tension silences the surveillance pathways that prevent cell cycle progression and correct erroneous kinetochore–microtubule attachments remains unclear. Here we show that SUMOylation dampens error correction to allow stable sister kinetochore biorientation and timely anaphase onset. The Siz1/Siz2 SUMO ligases modify the pericentromere-localized shugoshin (Sgo1) protein before its tension-dependent release from chromatin. Sgo1 SUMOylation reduces its binding to protein phosphatase 2A (PP2A), and weakening of this interaction is important for stable biorientation. Unstable biorientation in SUMO-deficient cells is associated with persistence of the chromosome passenger complex (CPC) at centromeres, and SUMOylation of CPC subunit Bir1 also contributes to timely anaphase onset. We propose that SUMOylation acts in a combinatorial manner to facilitate dismantling of the error correction machinery within pericentromeres and thereby sharpen the metaphase–anaphase transition.     

The intact parasympathetic nerve promotes submandibular gland regeneration through ductal cell proliferation

ObjectivesSalivary gland regeneration is closely related to the parasympathetic nerve; however, the mechanism behind this relationship is still unclear. The aim of this study was to evaluate the relationship between the parasympathetic nerve and morphological differences during salivary gland regeneration.Materials and MethodsWe used a duct ligation/deligation‐induced submandibular gland regeneration model of Sprague‐Dawley (SD) rats. The regenerated submandibular gland with or without chorda lingual (CL) innervation was detected by haematoxylin–eosin staining, real‐time PCR (RT‐PCR), immunohistochemistry and Western blotting. We counted the number of Ki67‐positive cells to reveal the proliferation process that occurs during gland regeneration. Finally, we examined the expression of the following markers: aquaporin 5, cytokeratin 7, neural cell adhesion molecule (NCAM) and polysialyltransferases.ResultsIntact parasympathetic innervation promoted submandibular gland regeneration. The process of gland regeneration was significantly repressed by cutting off the CL nerve. During gland regeneration, Ki67‐positive cells were mainly found in the ductal structures. Moreover, the expression of NCAM and polysialyltransferases‐1 (PST) expression in the innervation group was significantly increased during early regeneration and decreased in the late stages. In the denervated submandibular glands, the expression of NCAM decreased during regeneration.ConclusionsOur findings revealed that the regeneration of submandibular glands with intact parasympathetic innervation was associated with duct cell proliferation and the increased expression of PST and NCAM.     

The ScCas9++ variant expands the CRISPR toolbox for genome editing in plants

The development of clustered regularly interspaced palindromic repeats (CRISPR)-associated protein (Cas) variants with a broader recognition scope is critical for further improvement of CRISPR/Cas systems. The original Cas9 protein from Streptococcus canis (ScCas9) can recognize simple NNG-protospacer adjacent motif (PAM) targets, and therefore possesses a broader range relative to current CRISPR/Cas systems, but its editing efficiency is low in plants. Evolved ScCas9⁺ and ScCas9⁺⁺ variants have been shown to possess higher editing efficiencies in human cells, but their activities in plants are currently unknown. Here, we utilized codon-optimized ScCas9, ScCas9⁺ and ScCas9⁺⁺ and a nickase variant ScCas9n⁺⁺ to systematically investigate genome cleavage activity and cytidine base editing efficiency in rice (Oryza sativa L.). This analysis revealed that ScCas9⁺⁺ has higher editing efficiency than ScCas9 and ScCas9⁺ in rice. Furthermore, we fused the evolved cytidine deaminase PmCDA1 with ScCas9n⁺⁺ to generate a new evoBE4max-type cytidine base editor, termed PevoCDA1-ScCas9n⁺⁺. This base editor achieved stable and efficient multiplex-site base editing at NNG-PAM sites with wider editing windows (C₋₁–C₁₇) and without target sequence context preference. Multiplex-site base editing of the rice genes OsWx (three targets) and OsEui1 (two targets) achieved simultaneous editing and produced new rice germplasm. Taken together, these results demonstrate that ScCas9⁺⁺ represents a crucial new tool for improving plant editing.