Fast Isolation of Highly Active Photosystem Ⅱ Core Complexes from Spinach

Purification of photosystem Ⅱ (PSII) core complexes is a time-consuming and low-efficiency process. In order to isolate pure and active PSII core complexes in large amounts, we have developed a fast method to isolate highly active monomeric and dimeric PSII core complexes from spinach leaves by using sucrose gradient ultracentrifugation. By using a vertical rotor the process was completed significantly faster compared with a swing-out rotor. In order to keep the core complexes in high activity, the whole isolation procedure was performed in the presence of glycine betain and pH at 6.3. The isolated pigment-protein complexes were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, absorption spectroscopy, 77 K fluorescence spectroscopy and high performance liquid chromatography. Our results show that this method is a better choice for quick and efficient isolation of functionally active PSII core complexes.     

不同条件下两株溶磷菌溶磷量及葡萄糖脱氢酶基因表达与酶活分析北大核心CSCD

【目的】获得大豆根际土壤中溶磷能力较强的菌株,明确在菌株溶磷过程中葡萄糖脱氢酶(GDH)的作用特点及其基因的表达水平。【方法】利用溶磷圈方法分离与纯化溶磷菌株,采用Vitek 2系统和16S r RNA序列分析菌株的分类地位;测定2菌株的溶磷量、GDH活性,并根据GDH基因的保守区序列设计引物,克隆GDH基因,利用实时荧光定量PCR测定不同条件下基因的相对表达量。【结果】筛选出2株具有较强溶磷能力的溶磷菌,分别鉴定为Pseudomonas sp.和Enterobacter sp.,2菌株最高溶磷量分别为558μg/m L和478μg/m L;成功地克隆了2株溶磷菌的GDH基因,片段大小分别为2007 bp和2066 bp;2菌株在不同磷源、不同p H值培养基中GDH活性及基因表达量不同,菌株wj1在高磷条件下基因表达量最高,磷胁迫条件下基因表达量较低,而wj3在不同磷源条件下GDH基因表达量都较低。且GDH基因表达量及酶活的变化与wj3菌株溶磷量没有直接的关系。【结论】从大豆根际土壤中分离获得溶磷能力较强的菌株Pseudomonas sp.wj1和Enterobacter sp.Wj3,GDH活性及基因表达在2株菌溶磷过程中具有不同的作用特点,2菌株溶磷机制不完全相同。     

Role of a JAK3-dependent biochemical signaling pathway in platelet activation and aggregation

Here we provide experimental evidence that identifies JAK3 as one of the regulators of platelet function. Treatment of platelets with thrombin induced tyrosine phosphorylation of the JAK3 target substrates STAT1 and STAT3. Platelets from JAK3-deficient mice displayed a decrease in tyrosine phosphorylation of STAT1 and STAT3. In accordance with these data, pretreatment of human platelets with the JAK3 inhibitor WHI-P131 markedly decreased the base-line enzymatic activity of constitutively active JAK3 and abolished the thrombin-induced tyrosine phosphorylation of STAT1 and STAT3. Following thrombin stimulation, WHI-P131-treated platelets did not undergo shape changes indicative of activation such as pseudopod formation. WHI-P131 inhibited thrombin-induced degranulation/serotonin release as well as platelet aggregation. Highly effective platelet inhibitory plasma concentrations of WHI-P131 were achieved in mice without toxicity. WHI-P131 prolonged the bleeding time of mice in a dose-dependent manner and improved event-free survival in a mouse model of thromboplastin-induced generalized and invariably fatal thromboembolism. To our knowledge, WHI-P131 is the first anti-thrombotic agent that prevents platelet aggregation by inhibiting JAK3.     

The Effects of Using Trehalose as a Carbon Source on the Proliferation of Phalaenopsis and Doritaenopsis Protocorm-Like-Bodies

In this communication, the effects of trehalose and culture system on protocorm-like body (PLB) growth were investigated. PLB derived from Phalaenopsis and Doritaenopsis cultivars, which were grown on solidified trehalose amended NP medium showed higher proliferation rate than on NP medium containing sucrose. For P. ‘Hwa Feng Red Jewel’ and Dtp. ‘Mount Beauty×Su’s Red Lip’, the proliferation rates on solidified trehalose media were almost two times higher than those on sucrose media after 8-week culture. However, Knudson C (KC) medium did not reveal the similar results between trehalose and sucrose. In liquid culture system, both trehalose amended NP and KC media brought about better results than sucrose containing media for PLB proliferation. For culture system test, solidified media showed higher proliferation rate than liquid media under the same medium composition. Roller bottles were more suitable than flask-shaking cultures in liquid systems for PLB proliferation.     

弄岗北热带喀斯特季节性雨林15hm2动态监测样地树木死亡特征分析

以广西弄岗北热带喀斯特季节性雨林15 hm²森林动态监测样地为对象,结合2011年和2016年两次调查数据,分析5年间样地树木死亡个体的数量、径级结构和空间格局特征等。结果显示:2011年至2016年,样地有86.5%的树种出现了个体死亡的现象,死亡个体占个体总数的14.4%;死亡个体的聚集程度随空间尺度的增大而逐渐减弱;小径级个体死亡与周边邻体和环境的关联性较大;竞争是影响弄岗北热带喀斯特季节性云林树木死亡的主要因素。综合来看,北热带喀斯特季节性雨林内树木死亡并非是一个完全随机的过程,而是树木本身特征和生物与非生物环境共同作用的结果。     

Protection by hydroxychloroquine prevents placental injury in obstetric antiphospholipid syndrome

Obstetric antiphospholipid syndrome (OAPS) is mediated by antiphospholipid antibodies (aPLs, and anti‐β2 glycoprotein I antibody is the main pathogenic antibody), and recurrent abortion, preeclampsia, foetal growth restriction and other placental diseases are the main clinical characteristics of placental pathological pregnancy. It is a disease that seriously threatens the health of pregnant women. Hydroxychloroquine (HCQ) was originally used as an anti‐malaria drug and has now shown benefit in refractory OAPS where conventional treatment has failed, with the expectation of providing protective clinical benefits for both the mother and foetus. However, its efficacy and mechanism of action are still unclear. After clinical data were collected to determine the therapeutic effect, human trophoblast cells in early pregnancy were prepared and treated with aPL. After the addition of HCQ, the proliferation, invasion, migration and tubule formation of the trophoblast cells were observed so that the therapeutic mechanism of HCQ on trophoblast cells could be determined. By establishing an obstetric APS mouse model similar to the clinical situation, we were able to detect the therapeutic effect of HCQ on pathological pregnancy. The normal function of trophoblast cells is affected by aPL. Antibodies reduce the ability of trophoblast cells to invade and migrate and can impair tubule formation, which are closely related to placental insufficiency. HCQ can partially reverse these side effects. In the OAPS mouse model, we found that HCQ prevented foetal death and reduced the incidence of pathological pregnancy. Therefore, HCQ can improve pregnancy outcomes and reverse the aPL inhibition of trophoblast disease. In OAPS, the use of HCQ needs to be seriously considered.     

神经递质的可视化荧光检测技术研究进展

神经递质是神经系统中至关重要的组成部分,神经递质释放的时间和空间变化是神经网络中信息处理的核心,可视化监测神经递质的生物传感器是探究各类生理和病理活动的重要工具。文中综述了近年来具有较高时间和空间分辨率的监测神经递质时空分布变化技术的研究进展,介绍了对谷氨酸、多巴胺、γ-氨基丁酸和乙酰胆碱这4类重要的神经递质的检测方法,并归纳总结了各类检测方法的基本原理和优缺点,为设计具有高时空分辨率的神经递质传感器提供一个较为系统的参考。