RyR2 disease mutations at the C-terminal domain intersubunit interface alter closed-state stability and channel activation

Ryanodine receptors (RyRs) are ion channels that mediate the release of Ca²⁺ from the sarcoplasmic reticulum/endoplasmic reticulum, mutations of which are implicated in a number of human diseases. The adjacent C-terminal domains (CTDs) of cardiac RyR (RyR2) interact with each other to form a ring-like tetrameric structure with the intersubunit interface undergoing dynamic changes during channel gating. This mobile CTD intersubunit interface harbors many disease-associated mutations. However, the mechanisms of action of these mutations and the role of CTD in channel function are not well understood. Here, we assessed the impact of CTD disease-associated mutations P4902S, P4902L, E4950K, and G4955E on Ca²⁺− and caffeine-mediated activation of RyR2. The G4955E mutation dramatically increased both the Ca²⁺-independent basal activity and Ca²⁺-dependent activation of [³H]ryanodine binding to RyR2. The P4902S and E4950K mutations also increased Ca²⁺ activation but had no effect on the basal activity of RyR2. All four disease mutations increased caffeine-mediated activation of RyR2 and reduced the threshold for activation and termination of spontaneous Ca²⁺ release. G4955D dramatically increased the basal activity of RyR2, whereas G4955K mutation markedly suppressed channel activity. Similarly, substitution of P4902 with a negatively charged residue (P4902D), but not a positively charged residue (P4902K), also dramatically increased the basal activity of RyR2. These data suggest that electrostatic interactions are involved in stabilizing the CTD intersubunit interface and that the G4955E disease mutation disrupts this interface, and thus the stability of the closed state. Our studies shed new insights into the mechanisms of action of RyR2 CTD disease mutations.     

细菌蛋白质磷酸化修饰研究进展

细菌蛋白质磷酸化修饰是调控细菌基因表达的一种重要方式,在细菌诸多生命活动中发挥非常关键的作用。本文系统概括了近年来细菌蛋白质磷酸化修饰的种类、双组分调控系统中磷酸化修饰调控信号传导、酪氨酸残基磷酸化修饰以及丝/苏氨酸残基磷酸化修饰等,同时对不同种类细菌蛋白质磷酸化修饰的功能进行综述,这些研究将对人类了解细菌蛋白质翻译后修饰的磷酸化调控及其与控制细菌感染的关系提供参考价值。     

嵌合鞭毛蛋白和壳聚糖/三聚磷酸(CS/TPP)纳米凝胶封装对鼻接种幽门螺杆菌黏附素诱导的免疫应答的佐剂作用

[目的] 幽门螺杆菌黏附素A（HpaA）是幽门螺杆菌疫苗的一种有希望的抗原。探索嵌合鞭毛蛋白（cFLN）和壳聚糖/三聚磷酸（CS/TPP）纳米凝胶包封对鼻递送抗原HpaA诱导的免疫应答增强的佐剂作用。[方法] 通过将鼠伤寒沙门氏菌鞭毛蛋白FliC的D0、D1结构域与幽门螺杆菌鞭毛FlaA的D2、D3结构域相结合,构建嵌合鞭毛蛋白cFLN。作为分子内佐剂,嵌合鞭毛蛋白cFLN与黏附素（HpaA）连接构建复合抗原cFLN-HpaA。cFLN、HpaA、cFLN-HpaA在重组大肠杆菌中表达,并通过Ni-NTA预装色谱柱进行纯化。使用离子凝胶法分别将cFLN、HpaA、cFLN-HpaA包封到壳聚糖/三聚磷酸（CS/TPP）纳米凝胶中。[结果] 成功表达和纯化了cFLN、HpaA和cFLN-HpaA,并用离子凝胶法将这3种抗原包封在CS/TPP/纳米凝胶中,制备了包封cFLN的CS/TPP纳米凝胶（cFLN-HpaA NG）、包封HpaA的CS/TPP纳米凝胶（HpaA NG）、包封cFLN-HpaA的CS/TPP/纳米凝胶（cFLN-HpaA NG）。经鼻免疫小鼠后,与HpaA相比,cFLN-HpaA分别导致血清中IgG、IgG1和IgA含量增加2.09倍、1.4倍和2.62倍。与cFLN、HpaA和cFLN-HpaA相比,cFLN NG、HpaA NG和cFLN-HpaA NG分别使血清中IgA、IgG、IgG1和IgG2a的含量增加了1.28至1.71倍。[结论] cFLN和CS/TPP NG可以显著增强鼻腔输送的HpaA诱导的体液免疫。通过检测鼻腔免疫后胃黏膜中IFN-γ、IL-4、IL-17和SIgA的含量,与HpaA相比,cFLN-HpaA分别诱导IFN-γ、IL-4和SIgA的含量增加1.38、1.16和1.58倍。与cFLN-HpaA相比,cFLN-HpaA NG分别使小鼠胃黏膜中IFN-γ、IL-4、IL-17和SIgA的含量增加1.81、1.71、2.16和2.1倍。表明cFLN和CS/TPP NG可以显著增强Th1和Th17型免疫应答。小鼠体内免疫原性研究表明,分子内佐剂cFLN和纳米凝胶包封不仅可以有效增强鼻腔输送HpaA诱导的体液免疫应答,而且还可以增强小鼠胃黏膜中的黏膜免疫应答——Th1和Th17型免疫应答。因此,这些结果表明,cFLN-HpaA NG可能是有希望的经鼻输送的用于预防幽门螺杆菌感染的疫苗系统。     

Adjustment of the PIF7‐HFR1 transcriptional module activity controls plant shade adaptation

Shade caused by the proximity of neighboring vegetation triggers a set of acclimation responses to either avoid or tolerate shade. Comparative analyses between the shade‐avoider Arabidopsis thaliana and the shade‐tolerant Cardamine hirsuta revealed a role for the atypical basic‐helix‐loop‐helix LONG HYPOCOTYL IN FR 1 (HFR1) in maintaining the shade tolerance in C. hirsuta, inhibiting hypocotyl elongation in shade and constraining expression profile of shade‐induced genes. We showed that C. hirsuta HFR1 protein is more stable than its A. thaliana counterpart, likely due to its lower binding affinity to CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1), contributing to enhance its biological activity. The enhanced HFR1 total activity is accompanied by an attenuated PHYTOCHROME INTERACTING FACTOR (PIF) activity in C. hirsuta. As a result, the PIF‐HFR1 module is differently balanced, causing a reduced PIF activity and attenuating other PIF‐mediated responses such as warm temperature‐induced hypocotyl elongation (thermomorphogenesis) and dark‐induced senescence. By this mechanism and that of the already‐known of phytochrome A photoreceptor, plants might ensure to properly adapt and thrive in habitats with disparate light amounts.     

氮添加对中亚热带杜鹃灌丛凋落物生产和叶分解的影响

凋落物的生产和分解是生态系统养分循环的重要过程,受到大气氮沉降的深刻影响。但目前相关研究主要集中于森林和草地生态系统,氮沉降对灌丛生态系统凋落物养分归还的影响规律尚不清楚。因此选择亚热带分布广泛的杜鹃灌丛为研究对象,进行了为期两年的模拟氮沉降试验。试验设置4个处理:对照(CK, 0 g m-2 a-1)、低氮(LN, 2 g m-2 a-1)、中氮(MN, 5 g m-2 a-1)和高氮(HN, 10 g m-2 a-1)。结果显示:CK、LN、MN和HN 4种处理下,群落年平均凋落物量分别为(1936.54±358.9)、(2541.89±112.5)、(2342.97±519.8)、(2087.22±391.8) kg/hm²,LN、MN和HN处理样地的凋落量分别比对照样地高出32.68%、21.16%和7.93%;凋落叶、花果、凋落枝和其他组分占总凋落量的比例分别为75.75%、15.09%、7.70%和1.45%,不同浓度氮处理下各组分的凋落量均高于对照样地;凋落物组分表现出明显的季节动态:凋落叶在10—11月份达到峰值,凋落枝在10月份达到峰值,花果凋落物则在5月份凋落量最高,不同氮处理下凋落物的季节动态基本一致;白檀凋落叶分解速率显著高于杜鹃,二者分解95%所需时间分别为5.08—11.11 a和7.69—17.65 a,施氮使白檀凋落叶分解周期比对照样地缩短18.18%—54.28%;凋落叶分解过程中,N元素表现为富集-释放模式,P元素表现为富集模式。研究表明,氮添加能够促进群落中白檀凋落叶分解及N、P元素的释放,说明施氮可以调节凋落叶养分释放模式,对灌丛生态系统的养分循环具有调控作用。     

晚更新世东北亚现代人迁移与交流范围的初步研究

民族考古学曾运用相似性概念对许多地区狩猎采集者的行为进行了研究,相关的民族考古学资料为研究旧石器时代晚期现代人的迁移性提供了可能。随着东北亚地区出土黑曜岩遗物遗址的增加,相应的黑曜岩产地分析研究也日益增多,目前有关长白山黑曜岩产地研究的资料已显著累积。本文参考了现今狩猎采集者的民族学资料,以产自长白山的黑曜岩遗物及分布于特定区域的有柄尖刃器为研究对象,发现晚更新世时期(MIS 2)东北亚现代人拥有广大的直接或间接活动范围。对现代人迁移性的研究不仅为区域石器制作技术的对比分析提供了便利,也为了解古人类的生存环境及适应策略提供了重要资料。     

胆囊收缩素及受体基因多态性与精神分裂症的相关性研究

目的：探讨胆囊收缩素（cholecystokinin,CCK）基因、胆囊收缩素A受体（cholecystokininAreceptor。CCKAR）基因和胆囊收缩素B受体（cholecystokinin A recepmr,CCKBR）基因多态性与精神分裂症之间的相关性。方法：采用聚合酶链式反应．限制性片段长度多态性方法,对420例精神分裂症患者（病例组）和455例健康个体（对照组）三个基因的6个单核苷酸多态性（single nucleotide polymorphism,SNPs）位点（rs11571842、rs13069836、rs1800908、rs1800857、rs1042047、rs4758092）的多态性进行检测。并比较两组人群中基因型和等位基因频率分布的差异。结果：对照组6个SNPs位点的基因型频率分布均符合Hardy-Weinbere平衡（P〉0．05）;CCKAR基因rs1800857位点基因型频率分布在精神分裂症组与正常对照组间存在显著性差异（P〈0．000）,病例组T等位基因频率显著高于对照组（P〈0．01）。结论：CCKAR基因多态性与精神分裂症相关,携带T等位基因的个体可能更容易患精神分裂症。     

细菌黑色素的合成途径及生物功能研究进展

黑色素的合成是生物界从细菌到人类都普遍存在的现象。黑色素在生物体中具有抗紫外辐射、清除自由基等功能,对于生物的生长发育虽非必需,却能极大提高生物体的生存竞争能力。此外,黑色素合成途径中的关键酶类如酪氨酸酶能代谢不少酚类物质,在化工等领域具有实际应用价值。本文重点从细菌黑色素的种类、生物合成途径、黑色素的生物学功能方面进行阐述。