组织工程支架制备中超临界CO2技术的应用*

作为组织工程研究中三大要素之一,组织工程支架可为细胞的附着、迁移和增殖提供理想的环境。传统的组织工程支架制备方法,如粒子沥滤法、相分离法及静电纺丝法等在理论和技术上已较为成熟,但由于大多需要有机溶剂的参与,在制备过程中仍存在有机溶剂难以去除,以及支架孔洞难以控制、连通性较差等问题。超临界二氧化碳(supercritical carbon dioxide,SC-CO₂)密度近似液体,黏度和扩散系数近似气体,具有流动性强、溶解能力大、传热效率高等特殊的理化性质,与传统工艺相结合,可在绿色温和的反应体系中有效规避上述问题,在组织工程支架制备及药物负载方面具有广阔前景。     

功能性新型冠状病毒RBD结构域在毕赤酵母表面的展示*

目的:设计并构建新型冠状病毒(SARS-CoV-2)受体结合结构域(receptor binding domain,RBD)在毕赤酵母表面的展示体系,并对表面展示的RBD进行功能性评价,从而为以RBD为靶点的高通量药物筛选平台奠定基础。方法:将四种锚定分子与新冠病毒RBD融合,电转化至毕赤酵母中;通过细胞免疫荧光分析,筛选能够成功展示RBD的锚定系统;进一步分析其与血管紧张素转化酶2(angiotensin-converting enzyme 2,ACE2)受体的亲和力,证明展示在细胞表面RBD分子的功能。结果:仅Sed1p锚定分子能够有效呈递RBD至毕赤酵母细胞表面,展示效率约为70%;亲和力分析结果表明,ACE2受体和表面展示RBD的亲和力(K_D = 30.42 nmol/L)与溶液中RBD的亲和力(K_D = 16.00 nmol/L)较为接近。结论:这一体系能够在毕赤酵母表面高效地展示具有生物学功能的RBD,可用于抗新冠病毒RBD药物的高通量筛选和评价。     

MDP25 mediates the fine-tuning of microtubule organization in response to salt stress

Microtubules are dynamic cytoskeleton structures playing fundamental roles in plant responses to salt stress. The precise mechanisms by which microtubule organization is regulated under salt stress are largely unknown. Here, we report that Arabidopsis thaliana MICROTUBULE-DESTABILIZING PROTEIN 25 (MDP25; also known as PLASMA MEMBRANE-ASSOCIATED CATION-BINDING PROTEIN 1 (PCaP1)) helps regulate microtubule organization. Under salt treatment, elevated cytosolic Ca²⁺ concentration caused MDP25 to partially dissociate from the plasma membrane, promoting microtubule depolymerization. When Ca²⁺ signaling was blocked by BAPTA-AM or LaCl₃, microtubule depolymerization in wild-type and MDP25-overexpressing cells was slower, while there was no obvious change in mdp25 cells. Knockout of MDP25 improved microtubule reassembly and was conducive to microtubule integrity under long-term salt treatment and microtubule recovery after salt stress. Moreover, mdp25 seedlings exhibited a higher survival rate under salt stress. The presence microtubule-disrupting reagent oryzalin or microtubule-stabilizing reagent paclitaxel differentially affected the survival rates of different genotypes under salt stress. MDP25 promoted microtubule instability by affecting the catastrophe and rescue frequencies, shrinkage rate and time in pause phase at the microtubule plus-end and the depolymerization rate at the microtubule minus-end. These findings reveal a role for MDP25 in regulating microtubule organization under salt treatment by affecting microtubule dynamics.     

昆虫多样性三十年研究进展

当前, 全球昆虫数量和多样性均处于下降趋势, 而导致这一趋势的原因主要包括人为干扰及气候变化。本文基于森林、草地、农业、水生和土壤生态系统, 以植食性、访花、捕食性、寄生性、食果以及食腐昆虫为重点功能昆虫群, 综述了近三十年来国内外昆虫多样性研究领域的主要进展, 并分析了发展趋势。近年来, 昆虫多样性的研究维度不断拓展, 形态多样性研究不断深入, 系统发生多样性、功能多样性和遗传多样性等研究也显著加强。此外, 昆虫多样性研究的空间尺度也逐步扩大, 大尺度区域性研究甚至全球范围的调查持续增长。昆虫进化历史也被引入多样性格局研究中, 并随着系统发生信息学方法的普及而被整合到生态系统建成和生物多样性形成机制研究中。未来需要加强关键昆虫类群整合分类学研究、功能性状多样性、林冠昆虫多样性、互作网络结构等方向的研究。     

Natural Diversity and Phylogeny of Asian Red-Cheeked Squirrels (Rodentia,Sciuridae, Dremomys) in Eastern Indochina

Biology Bulletin - Based on new molecular data for mitochondrial (Cyt b) and nuclear (IRBP, RAG1) genes, as well as an extensive analysis of morphological material, we accessed actual species...     

A study on the protective effects of CpG oligodeoxynucleotide-induced mucosal immunity against lung injury in a mouse acute respiratory distress syndrome model

This study aims to determine the feasibility of using oligodeoxynucleotides with unmethylated cytosine-guanine dinucleotide sequences (CpG ODN) as an immunity protection strategy for a mouse model of acute respiratory distress syndrome (ARDS). This is a prospective laboratory animal investigation. Twenty-week-old BALB/c mice in Animal research laboratory were randomized into groups. An ARDS model was induced in mice using lipopolysaccharides (LPSs). CpG ODN was intranasally and transrectally immunized before or after the 3rd and 7th days of establishing the ARDS model. Mice were euthanized on Day 7 after the second immunization. Then, retroorbital bleeding was carried out and the chest was rapidly opened to collect the trachea and tissues from both lungs for testing. CpG ODN significantly improved the pathologic impairment in mice lung, especially after the intranasal administration of 50 μg. This resulted in the least severe lung tissue injury. Furthermore, interleukin-6 (IL-6) and IL-8 concentrations were lower, which was second to mice treated with the rectal administration of 20 µg CpG ODN. In contrast, the nasal and rectal administration of CpG ODN in BALB/c mice before LPS immunization did not appear to exhibit any significant protective effects. The intranasal administration of CpG ODN may be a potential treatment approach to ARDS. More studies are needed to further determine the protective mechanism of CpG ODN.     

双组分系统rcsC基因影响禽致病性大肠杆菌的致病性及相关生物学特性

【目的】双组分系统Rcs感受外界环境变化,并调控细菌的适应性及生存等。本文探讨Rcs双组分系统传感器激酶RcsC对禽致病性大肠杆菌(avian pathogenic Escherichia coli,APEC)相关生物学特性及致病性的影响。【方法】采用Red同源重组的方法构建rcsC基因缺失株,并利用互补质粒构建互补株,然后比较野生株、基因缺失株与互补株的生长特性、运动性、生物被膜、凝集沉淀能力、致病力及毒力基因转录水平的差异。【结果】rcsC基因缺失不影响APEC的生长速度,然而,缺失RcsC导致APEC的运动能力升高、生物被膜形成能力降低和凝集能力增强。凝集试验结果显示rcsC基因有助于APEC的凝集沉降。细胞黏附入侵结果表明,rcsC在APEC侵袭DF-1细胞过程中发挥作用,而对黏附能力无影响。动物感染试验结果表明rcsC基因缺失能显著降低APEC的毒力。荧光定量PCR检测结果表明,rcsC基因缺失株中ompA、aatA、fyuA和luxS基因的转录水平均显著降低,而fimC和tsh基因的转录水平显著升高。【结论】RcsC参与调控APEC的运动性、生物被膜形成、凝集沉降和致病力。     

pLoc_bal-mGpos: Predict subcellular localization of Gram-positive bacterial proteins by quasi-balancing training dataset and PseAAC

Knowledge of protein subcellular localization is vitally important for both basic research and drug development. With the avalanche of protein sequences emerging in the post-genomic age, it is highly desired to develop computational tools for timely and effectively identifying their subcellular localization purely based on the sequence information alone. Recently, a predictor called “pLoc-mGpos” was developed for identifying the subcellular localization of Gram-positive bacterial proteins. Its performance is overwhelmingly better than that of the other predictors for the same purpose, particularly in dealing with multi-label systems in which some proteins, called “multiplex proteins”, may simultaneously occur in two or more subcellular locations. Although it is indeed a very powerful predictor, more efforts are definitely needed to further improve it. This is because pLoc-mGpos was trained by an extremely skewed dataset in which some subset (subcellular location) was over 11 times the size of the other subsets. Accordingly, it cannot avoid the bias consequence caused by such an uneven training dataset. To alleviate such bias consequence, we have developed a new and bias-reducing predictor called pLoc_bal-mGpos by quasi-balancing the training dataset. Rigorous target jackknife tests on exactly the same experiment-confirmed dataset have indicated that the proposed new predictor is remarkably superior to pLoc-mGpos, the existing state-of-the-art predictor in identifying the subcellular localization of Gram-positive bacterial proteins. To maximize the convenience for most experimental scientists, a user-friendly web-server for the new predictor has been established at http://www.jci-bioinfo.cn/pLoc_bal-mGpos/, by which users can easily get their desired results without the need to go through the detailed mathematics.