构建我国生物多样性评价的指标体系

生物多样性指标体系的建设过程长期而复杂,需要结合科学研究、监测以及决策制定,并基于合理的结构进行指标设计.构建适宜的生物多样性评价指标体系、监测评估生物多样性状况及变化趋势,已被纳入我国国家生物多样性战略及其行动计划.本文结合国内外经验,从指标的逻辑框架、空间尺度、时间尺度、指标类型、评价方法等5个方面探讨了指标体系构...     

浅论传统义利观在医学类大学生培育中的价值

随着传统义利观在中国传统文化中的不断丰富和发展,深深地影响着人们的价值观,并在人们的心中形成一种道德自律和民族自觉,对人们的行为发挥着重要的指导作用。在对医学生的培养教育中,往往只注重科学教育,缺乏包括义利观教育等在内的人文教育成为医学生培养系统亟待解决的问题。作为医学院校应当明确当代医患矛盾频出的关键所在,强调医学生建立＂重义轻利＂的人文理念,不断提高医疗服务道德水平。     

The Global Sequence Signature algorithm unveils a structural network surrounding heavy chain CDR3 loop in Camelidae variable domains

Background

A large fraction of camelid (camels and llamas) antibodies is composed of heavy chain-only homodimers, able to recognise antigens with their variable domain. Events in somatic assembly and maturation of antibodies such as hypermutations and rearrangement of variable loops (CDRs — complementary determining regions) and selection among a wide range of framework variants are generally considered to be random processes.

Methods

An original algorithmic approach (Global Sequence Signature—GSS) was developed, able to take into account multiple functional and/or local sequence properties to detect scattered evolutionary constraints into sequences.

Results

Using the GSS approach, we show that the length of the main hypervariable loop (CDR3) is linked to the nature of 19 surrounding residues on the scaffold. Surprisingly, the relation between CDR3 size and scaffold residues strongly depends on the considered species, illustrating either significant differences in selection mechanisms or functional constraints during antibody maturation.

Conclusions

Combined with the statistical coupling analysis (SCA) approach at the level of scaffold residues, this study has unravelled a robust interaction network on antibody structure surrounding the CDR3 loop.

General significance

In addition to the general applicability of the GSS algorithm, which can bring together functional and sequence data to locate hot spots of constrained evolution, the relationship between CDR3 and scaffold discussed here should be taken into account in protein engineering when designing antibody libraries.     

纳米卟啉金属有机骨架对斑马鱼神经系统发育的作用*

目的:研究纳米卟啉金属有机骨架(NPMOF)对斑马鱼幼鱼神经系统发育的作用。方法:斑马鱼胚胎在发育6 h(hpf)后随机分为两组:对照组(n=500)和暴露组(n=500),对照组斑马鱼孵化于E3溶液中,暴露组于100 mg/L的NPMOF-E3溶液中,持续暴露至28、48、72、96或120 hpf。以20条斑马鱼为一批,在28、48、72、96和120 hpf分别提取3批实验组和对照组的总RNA用于RT-PCR;在120 hpf,实验组和对照组分别取20条PTU处理过的斑马鱼用于整体胚胎原位杂交,同样是在120 hpf,每组取150条用于免疫荧光染色,30条用于行为学测试。NPMOF的形状和尺寸用透射电镜测定,其光学特性由紫外分光光度计和荧光光谱仪测定;通过免疫荧光、整体胚胎原位杂交和RT-PCR方法检测各类神经细胞的发育;行为学测试用来监测斑马鱼运动状态的改变。结果:与正常组比较,NPMOF暴露组中神经发育相关基因的表达明显升高(P＜0.05),müller细胞和星形胶质细胞的数量明显增加(P＜0.05),神经元和少突胶质细胞的分布与形态未显示出差异;行为学测试中,斑马鱼的总运动距离、快速运动时间和运动速度的值显著增加(P＜0.05),总静止时间明显降低(P＜0.05)。结论:100 mg/L NPMOF溶液的持续暴露对斑马鱼神经系统发育,特别是视网膜中müller细胞和脑中星形胶质细胞的发育有促进作用。     

Evaluating success of various restorative interventions through drone‐ and field‐collected data,using six putative framework species in Argentinian Patagonia

Field data and unmanned aerial vehicles, also known as drones, were used to analyze a long‐term experiment in a severely degraded area of the “Monte,” one of the most arid and degraded biomes in Argentina. Field methods and drone orthoimages obtained from flights of a quadcopter at 20 and 40 m were used to compare plantation plots versus natural recovery on scarified sites, and the field performance of six putative framework species under four different treatments was evaluated. After 5 years of recovery in soils with almost no organic matter and mean annual rainfall averaging 145 mm, plantation plots had high survival rates (>65%) for all species as determined through both field survey and drone imagery. Three species were planted with a greater number of seedlings due to their availability in nurseries. For these species experimental treatments were studied statistically. Independently of treatment applied (control; 1/2 L hydrogel; 1 L hydrogel; 1 L of hydrogel + 1/2 kg of organic compost), highest survival rates were found for P. flexuosa var. depressa (88% ± 14.8) and A. lampa (84% ± 14.8). Drone images and field data both showed that these two putative framework species had the highest plant cover. In sharp contrast, mechanical scarification without planting or other treatments induced very low recovery (<2%). We demonstrate that drone imagery provides a new and very valuable tool for evaluating and monitoring restorative interventions in drylands.     

Solvent‐Free Synthesis of Thin,Flexible, Nonflammable Garnet‐Based Composite Solid Electrolyte for All‐Solid‐State Lithium Batteries

Thin solid‐state electrolytes with nonflammability, high ionic conductivity, low interfacial resistance, and good processability are urgently required for next‐generation safe, high energy density lithium metal batteries. Here, a 3D Li_6.75La₃Zr_1.75Ta_0.25O₁₂ (LLZTO) self‐supporting framework interconnected by polytetrafluoroethylene (PTFE) binder is prepared through a simple grinding method without any solvent. Subsequently, a garnet‐based composite electrolyte is achieved through filling the flexible 3D LLZTO framework with a succinonitrile solid electrolyte. Due to the high content of garnet ceramic (80.4 wt%) and high heat‐resistance of the PTFE binder, such a composite electrolyte film with nonflammability and high processability exhibits a wide electrochemical window of 4.8 V versus Li/Li⁺ and high ionic transference number of 0.53. The continuous Li⁺ transfer channels between interconnected LLZTO particles and succinonitrile, and the soft electrolyte/electrode interface jointly contribute to a high ambient‐temperature ionic conductivity of 1.2 × 10^?4 S cm^?1 and excellent long‐term stability of the Li symmetric battery (stable at a current density of 0.1 mA cm^?2 for over 500 h). Furthermore, as‐prepared LiFePO₄|Li and LiNi_0.5Mn_0.3Co_0.2O₂|Li batteries based on the thin composite electrolyte exhibit high discharge specific capacities of 153 and 158 mAh g^?1 respectively, and desirable cyclic stabilities at room temperature.     

南海北部莺歌海盆地新近纪古环境与层序地层格架再认识

利用莺歌海盆地钻井中获得的丰富的有孔虫、钙质超微化石等微体古生物资料,对研究区新近纪各地层沉积时期的古环境及演化进行了研究。结合古环境及地震资料分析,重新认识了莺歌海盆地新近纪各层序界面。S40、S30、S28、S27等界面都具明显的峡谷侵蚀特征。另外,①号断层上升盘地层受峡谷侵蚀搬运后在下部S29界面上形成较好的储层,是下一步油气勘探的重要方向之一。     

Crystal structure of the streptococcal superantigen SpeI and functional role of a novel loop domain in T cell activation by group V superantigens

Superantigens (SAgs) are potent microbial toxins that bind simultaneously to T cell receptors (TCRs) and class II major histocompatibility complex molecules, resulting in the activation and expansion of large T cell subsets and the onset of numerous human diseases. Within the bacterial SAg family, streptococcal pyrogenic exotoxin I (SpeI) has been classified as belonging to the group V SAg subclass, which are characterized by a unique, relatively conserved ∼15 amino acid extension (amino acid residues 154 to 170 in SpeI; herein referred to as the α3-β8 loop), absent in SAg groups I through IV. Here, we report the crystal structure of SpeI at 1.56 Å resolution. Although the α3-β8 loop in SpeI is several residues shorter than that of another group V SAg, staphylococcal enterotoxin serotype I, the C-terminal portions of these loops, which are located adjacent to the putative TCR binding site, are structurally similar. Mutagenesis and subsequent functional analysis of SpeI indicates that TCR β-chains are likely engaged in a similar general orientation as other characterized SAgs. We show, however, that the α3-β8 loop length, and the presence of key glycine residues, are necessary for optimal activation of T cells. Based on Vβ-skewing analysis of human T cells activated with SpeI and structural models, we propose that the α3-β8 loop is positioned to form productive intermolecular contacts with the TCR β-chain, likely in framework region 3, and that these contacts are required for optimal TCR recognition by SpeI, and likely all other group V SAgs.