日本血吸虫性病兔肝纤维化的酶组织化学研究

目的观察日本血吸虫感染家兔导致肝脏发生纤维化后的肝组织酶学改变.方法将23只成年健康大耳白兔分为正常对照组(N)8只,模型组(M)15只,M组采用腹贴法(日本血吸虫尾蚴180条/只,持续15min)感染血吸虫,六周后服用吡喹酮行杀虫治疗.于实验的第13周将全部动物麻醉后剖腹取肝组织.肝组织行HE染色和电镜观察;酶组织化学方法检测单胺氧化酶(MAO)、一氧化氮合酶(NOS)、琥珀酰脱氢酶(SDH)、乳酸脱氢酶(LDH)在器官的表达活性.结果在血吸虫感染家兔的第13周可观察到肝组织明显纤维化;模型组中MAO、NOS、LDH活性明显高于正常对照组,而SDH活性则明显降低.结论慢性血吸虫感染引起的肝纤维化导致肝细胞缺血缺氧,影响NOS、SDH、LDH活性,加重肝细胞损伤.     

类黄酮对AM真菌及宿主植物的影响研究

类黄酮[apigenin(4,5,7-trihydroxyflavone,4,5,7-三羟基黄酮)和hesperitin(3?5,7trihydroxy4?methoxyflavanone,3?5,7-三羟-4-甲氧基黄烷酮)]对接种AM真菌的紫云英的生物量、AM真菌侵染率、菌丝ALP(碱性磷酸酶)和SDH(琥珀酸脱氢酶)活性都有显著影响。对于Glomusintraradices侵染的紫云英的生物量,4,5,7-三羟基黄酮处理组第6周有显著差异(生物量分别为6.3g、5.7g和6.5g,而对照为3.0g),3?5,7-三羟-4-甲氧基黄烷酮处理组三次取样都有显著差异;对于Endo-1(一个商业菌剂,由Glomusintraradices和Glomusmosseae组成)侵染的紫云英的生物量,4?5,7-三羟基黄酮处理组第6周1.5mmol/L组和第9周150nmol/L组都有显著差异(生物量分别为7.2g和16.8g,而对照为4.1g和8.1g),3?5,7-三羟-4?甲氧基黄烷酮处理组第6、9周都有显著差异,尤以第9周150nmol/L组差异更大(生物量为14.4g,而对照为8.1g)。对于G.intraradices的侵染率,与对照相比,4?5,7-三羟基黄酮处理组三次取样都有显著差异(第9周对照为36.6%,而处理组分别为71.5%、80.8%和75.9%);3?5,7-三羟-4?甲氧基黄烷酮处理组三次取样也有显著差异,尤以150nmol/L组效果最好(第9周AM真菌侵染率为94.8%,而对照为36.6%);对于Endo-1的侵染率,与对照相比,4,5,7-三羟基黄酮处理组三次取?     

In vitro kinetics of the rat brain succinate dehydrogenase inhibition by hexachlorophene.

Brain succinate dehydrogenase (SDH) activity was inhibited by in vitro hexachlorophene (HCP) with a half inhibitory concentration (IC50) of 0.65 x 10(-3) M. The HCP exerted noncompetitive inhibition at 0.5 mM (IC50) on SDH activity. The brain SDH demands more energy of activation (deltaE) in the presence of HCP. The ionizable groups of SDH such as the sulfhydral group of cysteine and alpha-amino groups of cysteine were not altered qualitatively in the presence of HCP.     

Succinate dehydrogenase in Arabidopsis thaliana is regulated by light via phytochrome A

The effect of light on succinate dehydrogenase (SDH) activity and mRNA content was studied in Arabidopsis thaliana plants. The transition from darkness to light caused a short transient increase in the SDH activity followed by a decrease to a half of the original activity. The white or red light were found to be down-regulating factors for the mRNA content of the sdh1-2 and sdh2-3 genes and SDH catalytic activity both in A. thaliana wild-type plants and in the mutant deficient in the phytochrome B gene, but not in the mutant deficient in the phytochrome A gene, while the far-red light of 730 nm reversed the red light effect. It is concluded that phytochrome A participates in the regulation of mitochondrial respiration through effect on SDH expression.     

大鼠心肌线粒体缺血再灌损伤及SOD抗缺血再灌损伤作用的形态计量研究

研究了在体大鼠心肌缺血再灌模型心肌线粒体再灌损伤和SOD抗缺血再灌损伤的作用。实验分为:A组(缺血再灌组)B组(SOD组)和C组(假手术组)。电镜见A组线粒体高度肿胀、外膜缺损、嵴断裂溶解,出现无定形致密体、四膜嵴和杆状嵴等改变。B组线粒体轻度或中度肿胀、少数有轻度嵴溶解。个别线粒体内出现无定形致密体。三组线粒体超微结构立体计量数据比较,A组线粒体密度、线粒体体密度与肌原纤维体密度比率增高((P<0.01),线粒体比表面和比膜面降低(P<0.01)。自身动图像分析仪检测SDH反应灰度值A组呈强损伤反应,B组反应较轻,二者差别有显著性(P<0.05)。结果表明,心肌缺血再灌可致线粒体发生不可逆性损伤,SOD能减轻线粒体缺血再灌性损伤。     

Serine utilization in mouse liver: influence of caloric restriction and aging

The influence of caloric restriction (CR) on the activities of hepatic serine metabolizing enzymes in young (3 months) and old (30 months) mice was studied. Serine dehydratase (SDH) activity increased markedly with age in both diet groups and in old mice was higher in the CR group. No effects of CR were observed in the young. Serine:pyruvate transaminase (SPT) and glycerate kinase activities were unaffected by age and diet. However, glycerate dehydrogenase activity was decreased in old CR mice but not in young CR. The results of this study show that long-term CR influenced serine utilization only in the pathway catalyzed by SDH. This suggests that in mouse liver this pathway is critical for serine utilization in gluconeogenesis, while the SPT pathway plays a minor role. The increase in SDH activity with long-term CR is consistent with sustained increase in gluconeogenesis.     

Cancer-associated 2-oxoglutarate analogues modify histone methylation by inhibiting histone lysine demethylases

Histone lysine demethylases (KDMs) are 2-oxoglutarate-dependent dioxygenases (2-OGDDs) that regulate gene expression by altering chromatin structure. Their dysregulation has been associated with many cancers. We set out to study the catalytic and inhibitory properties of human KDM4A, KDM4B, KDM5B, KDM6A and KDM6B, aiming in particular to reveal which of these enzymes are targeted by cancer-associated 2-oxoglutarate (2-OG) analogues. We used affinity-purified insect cell-produced enzymes and synthetic peptides with trimethylated lysines as substrates for the in vitro enzyme activity assays. In addition, we treated breast cancer cell lines with cell-permeable forms of 2-OG analogues and studied their effects on the global histone methylation state. Our data show that KDMs have substrate specificity. Among the enzymes studied, KDM5B had the highest affinity for the peptide substrate but the lowest affinity for the 2-OG and the Fe^2 + cosubstrate/cofactors. R-2-hydroxyglutarate (R-2HG) was the most efficient inhibitor of KDM6A, KDM4A and KDM4B, followed by S-2HG. This finding was supported by accumulations of the histone H3K9me3 and H3K27me3 marks in cells treated with the cell-permeable forms of these compounds. KDM5B was especially resistant to inhibition by R-2HG, while citrate was the most efficient inhibitor of KDM6B. We conclude that KDM catalytic activity is susceptible to inhibition by tumorigenic 2-OG analogues and suggest that the inhibition of KDMs is involved in the disease mechanism of cancers in which these compounds accumulate, such as the isocitrate dehydrogenase mutations.     

高浓度2-KLG对氧化葡萄糖酸杆菌WSH-003中2-KLG合成途径关键基因表达的影响

【目的】研究高浓度的2-KLG对其生产菌株氧化葡萄糖酸杆菌生产过程中关键的脱氢酶合成基因、辅因子合成基因及其转运蛋白编码基因的影响。【方法】测定高浓度梯度2-KLG下氧化葡萄糖酸杆菌的生长情况,确定合适的添加浓度对氧化葡萄糖酸杆菌进行胁迫。使用实时定量PCR技术检测2-KLG合成中关键山梨醇脱氢酶基因sld AB、关键辅因子PQQ合成基因pqq ABCDE及5个潜在转运蛋白合成基因的变化。【结果】根据氧化葡萄糖酸杆菌在2-KLG高浓度梯度下生长测定实验结果,选定40、80和120 g/L 2-KLG作为添加浓度。实时定量PCR结果显示,在高浓度的2-KLG压力下,PQQ合成基因pqq ABCDE未受到显著影响,山梨醇脱氢酶基因sld AB以及部分PQQ潜在转运蛋白编码基因的表达均显著下调。【结论】高浓度2-KLG会抑制氧化葡萄糖酸杆菌中山梨醇脱氢酶基因的表达,有可能会影响辅酶PQQ的转运,但不会显著影响辅酶PQQ的合成。