Mechanisms of chromatin-based epigenetic inheritance

Multi-cellular organisms such as humans contain hundreds of cell types that share the same genetic information(DNA sequences), and yet have different cellular traits and functions. While how genetic information is passed through generations has been extensively characterized, it remains largely obscure how epigenetic information encoded by chromatin regulates the passage of certain traits, gene expression states and cell identity during mitotic cell divisions, and even through meiosis. In this r...     

肠道真菌研究进展

真菌菌群是肠道菌群的重要组成部分,在肠道微生态稳态的维持和宿主的免疫调节中发挥重要作用。肠道真菌失调通常和肠道疾病甚至肠道外疾病有关。本文就肠道真菌的定殖与组成、真菌菌群对肠道微生态的调控、菌群失调促进疾病的发展机制、基于肠道真菌的治疗策略和肠道真菌的鉴定分析方法等方面的进展进行了综述和展望,旨在系统认识肠道真菌调节宿主健康和促进疾病发生的机制,为相关疾病的诊断和治疗提供重要参考。     

薄层层析-比色法测定降糖安胶囊中胡芦巴皂苷B的含量

建立薄层层析-比色法测定降糖安胶囊中胡芦巴皂苷B含量的方法。采用硅胶H薄层板,氯仿：甲醇：醋酸：水(25：12：2：2)为展开剂,在碘蒸气中定位,用高氯酸显色,325nm波长处检测,点样量在35ug～385ug范围内呈现良好的线性关系,其回归方程为A=285．6C-1．313,相关系数r=0．9991,平均回收率为96．23％,RSD=1．75％。本法准确,适用于该药的质量控制。     

Complete genome sequence of a bovine viral diarrhea virus 2 from commercial fetal bovine serum

We isolated a bovine viral diarrhea virus (BVDV) from commercial fetal bovine serum and designated it HLJ-10. The complete genome is 12,284 nucleotides (nt); the open reading frame is 11,694 nt, coding 3,898 amino acids. Phylogenetic analysis indicated that this strain belongs to BVDV group 2.     

巨膜长蝽的形态特征和生物学特性

【目的】近年来巨膜长蝽Jakowleffia setulosa(Jakovlev)由以往稳定种群的荒漠昆虫上升为暴发性发生并迁移至农区危害的农业害虫。由于缺乏对巨膜长蝽基础生物学的相关研究,对其开展监测预警和农业防治存在困难。开展巨膜长蝽个体生物学研究,填补研究空白对于有效监测预报和防控提供可靠的依据,同时能为下一步分析巨膜长蝽成灾规律提供基础数据。【方法】本文通过室内观察和野外调查相结合,系统阐明该种形态特征、生活史、习性和行为等生物学特性。【结果】巨膜长蝽在宁夏中部干旱带一年发生2代,5月中旬和10月中下旬是两个发生高峰期,6月中旬至8月中旬以成虫进入滞育状态,11月下旬以成虫越冬;雌成虫的平均寿命为(32.14±2.34)d,雄成虫的平均寿命为(28.00±3.13)d,雌雄性比为1︰1.9,有多次交尾多次产卵的习性,每头雌虫抱卵量10粒左右,平均产卵量10~15粒左右;食性杂,群居危害,喜食白茎盐生草(Halogeton arachnoideus)等沙生草本植物的种子。【结论】该虫具有以成虫形态越冬和滞育、迁移性强等生物学特性。在生态环境发生较大变动后,能够经历逆境后迅速恢复种群并迁移危害。宁夏中南部地区种植结构调整,极大改变了该地区的荒漠生态环境,促使巨膜长蝽在经过夏季高温滞育恢复种群后无法获得足够野生寄主的情况下,大规模迁入农田系统危害。     

Requirement for Lamin B Receptor and Its Regulation by Importin β and Phosphorylation in Nuclear Envelope Assembly during Mitotic Exit

Lamin B receptor (LBR), a chromatin and lamin B-binding protein in the inner nuclear membrane, has been proposed to target the membrane precursor vesicles to chromatin mediated by importin β during the nuclear envelope (NE) assembly. However, the mechanisms for the binding of LBR with importin β and the membrane targeting by LBR in NE assembly remain largely unknown. In this report, we show that the amino acids (aa) 69–90 of LBR sequences are required to bind with importin β at aa 45–462, and the binding is essential for the NE membrane precursor vesicle targeting to the chromatin during the NE assembly at the end of mitosis. We also show that this binding is cell cycle-regulated and dependent on the phosphorylation of LBR Ser-71 by p34^cdc2 kinase. RNAi knockdown of LBR causes the NE assembly failure and abnormal chromatin decondensation of the daughter cell nuclei, leading to the daughter cell death at early G₁ phase by apoptosis. Perturbation of the interaction of LBR with importin β by deleting the LBR N-terminal spanning region or aa 69–73 also induces the NE assembly failure, the abnormal chromatin decondensation, and the daughter cell death. The first transmembrane domain of LBR promotes the NE production and expansion, because overexpressing this domain is sufficient to induce membrane overproduction of the NE. Thus, these results demonstrate that LBR targets the membrane precursor vesicles to chromatin by interacting with importin β in a LBR phosphorylation-dependent manner during the NE assembly at the end of mitosis and that the first transmembrane domain of LBR promotes the LBR-bearing membrane production and the NE expansion in interphase.     

Simazine application inhibits nitrification and changes the ammonia-oxidizing bacterial communities in a fertilized agricultural soil

s-Triazine herbicides are widely used for weed control, and are persistent in soils. Nitrification is an essential process in the global nitrogen cycle in soil, and involves ammonia-oxidizing Bacteria (AOB) and ammonia-oxidizing Archaea (AOA). In this study, we evaluated the effect of the s-triazine herbicide simazine on the nitrification and on the structure of ammonia-oxidizing microbial communities in a fertilized agricultural soil. The effect of simazine on AOB and AOA were studied by PCR-amplification of amoA genes of nitrifying Bacteria and Archaea in soil microcosms and denaturing gradient gel electrophoresis (DGGE) analyses. Simazine [50?μg g(-1) dry weight soil (d.w.s)] completely inhibited the nitrification processes in the fertilized agricultural soil. The inhibition by simazine of ammonia oxidation observed was similar to the reduction of ammonia oxidation by the nitrification inhibitor acetylene. The application of simazine-affected AOB community DGGE patterns in the agricultural soil amended with ammonium, whereas no significant changes in the AOA community were observed. The DGGE analyses strongly suggest that simazine inhibited Nitrosobacteria and specifically Nitrosospira species. In conclusion, our results suggest that the s-triazine herbicide not only inhibits the target susceptible plants but also inhibits the ammonia oxidation and the AOB in fertilized soils.     

Enhanced chemiluminescence enzyme‐linked immunoassay for the determination of DNA methyltransferase 1 in human serum

The occurrence of many diseases is closely related to the high expression of DNA methyltransferase 1 (DNMT1). However, most studies are focused on the detection of DNMT1 activity, a few are concerned with the detection of DNMT1 content. In this study, we developed a simple and highly sensitive chemiluminescence (CL) assay for the detection of DNMT1 content. In this method, anti‐DNMT1 monoclonal antibody was coated on a polystyrene microplate to capture DNMT1. Then anti‐DNMT1 polyclonal antibody and goat anti‐rabbit immunoglobulin G with horseradish peroxidase (IgG‐HRP) were respectively added to combine with captured DNMT1 to form a sandwich structure. Finally, the HRP could catalyze CL substrate and achieve CL signal response. Based on this novel sensitive strategy, the recovery percents were in the ranges from 71.5% to 91.0%. The precision of intra‐assays and inter‐assays were 5.45%–11.29% and 7.03%–11.25%, respectively. The method was successfully applied for the determination of DNMT1 in human serum. The detection results of serum samples showed that the proposed assay had a high correlation with enzyme‐linked immunosorbent assay (ELISA) kit. Compared with the ELISA kit (limit of detection = 0.1 ng/mL), the method has a lower limit of detection of 0.042 ng/mL. Therefore, our method has the potential for the detection of DNMT1 content in clinical diagnosis.     

Crystallization and preliminary X-ray crystallographic analysis of spruce budworm antifreeze protein.

Antifreeze proteins have the ability to bind to ice with high affinity and inhibit further crystal growth. The insect antifreeze protein from spruce budworm exhibits very high thermal hysteresis activity and is implicated in the protection of overwintering larvae from freezing. This protein has been crystallized in 20-25% polyethylene glycol (Mr 6000), 0.4 M NaCl, 0.1 M Tris-HCl, pH 8.5, by vapor diffusion using the hanging drop method. The resulting crystals are very thin (typically <0.01 mm in the shortest dimension), and only after repeated seeding could crystals be grown large enough for data collection using synchrotron radiation. The crystals belong to the monoclinic space group C2, with cell dimensions a = 82.28 A, b = 62.29 A, c = 63.63 A, and beta = 113.7 degrees. Molecules in the asymmetric unit are related by a twofold axis of symmetry with two molecules present. Native data to a resolution of 2.6 A have been collected with 90.3% completeness and a Rsym of 6.9%.     

The role of GSK3beta in the development of the central nervous system

Glycogen synthase kinase 3β (GSK3β) is a multifunctional serine/threonine kinase.It is particularly abundant in the developing central nervous system (CNS).Since GSK3β has diverse substrates ranging fr...