两种测试方法对DPPH分光光度法测试结果的影响

目的:比较固定反应时间法和动力学监测法的准确性。方法:用固定反应时间法和动力学监测法分别测定维生素C(Vc)、二丁基羟基甲苯(BHT)对二苯代苦味酰自由基(DPPH)的清除作用,通过F检验和t检验来揭示两种方法的差异。结果:通过动力学监测法得到的测试结果更能准确的反映测试样品对DPPH自由基的清除能力。结论:建议在用DPPH分光光度法过程中使用动力学监测法。     

Electron microscopic examination of the orexin immunoreactivity in the dorsal raphe nucleus

The ultrastructure and the synaptic relationships of the orexin-A-like immunoreactive fibers in the dorsal raphe nucleus were examined with an immunoelectron microscopic method. At the electron microscopic level, most of the immunoreactive fibers, a varicosity appearance at the light microscopic level, were found as axon terminals. The large dense-cored vesicles contained in the immunoreactive axon terminals were the most intensely immunostained organellae. These axon terminals were often found to make synapses. While the axo-dendritic synapses were usually asymmetric in appearance, the axo-somatic synapses were symmetric. Orexin-A-like immunoreactive processes with no synaptic vesicles were also found. These processes often received asymmetric synapses. With less frequency, the synapses were found between the orexin-like immunoreactive processes. The results suggest that the orexin peptides are stored in the large dense-cored vesicles; the orexin-containing fibers may have influences on the physiological activities of the dorsal raphe nucleus through direct synaptic relationships.     

生物转化生产D-塔格糖的食品级菌种选育及L-阿拉伯糖异构酶的克隆表达

L-阿拉伯糖异构酶(L-arabinose isomerase,L-AI)是一种可以催化D-半乳糖为D-塔格糖的胞内异构化酶。随着塔格糖在食品工业中越来越广泛的应用,能够将半乳糖转化为塔格糖的食品级微生物以及食品级来源的L-AI受到更大的关注。文中从各种酸奶制品、泡菜及其他一些食品中采集不同的样品,筛选出1株具有L-AI酶活的食品级菌株,经过生理生化鉴定以及16S rDNA序列测定,确定该菌株为戊糖片球菌,命名为Pediococcus pentosaceus PC-5。以该菌基因组为模板,克隆L-AI基因,并在大肠杆菌BL21成功地异源表达。表达产物经粗提取后,在40℃下加入Mn2+,使D-半乳糖转化为D-塔格糖的转化率为33%。     

The intrinsic mechanisms underlying the maturation of programming sequential spikes at cerebellar Purkinje cells

Cerebellum is involved in the motion coordination and working memory, to which the programming of sequential spikes at Purkinje cells is essential. It is not clear about the intrinsic mechanisms underlying spike capacity and timing precision as well as their postnatal maturation. We investigated the programming and intrinsic property of sequential spikes at Purkinje neurons during postnatal development by whole-cell recording in cerebellar slices. Cerebellar Purkinje neurons demonstrate the increasing of spike capacity and timing precision, as well as the lowering of refractory periods and threshold potentials during the postnatal maturation. In addition, the correlation between spike parameters and intrinsic properties converts to be more linear. This postnatal plasticity of neuronal intrinsic properties improves the timing precision and capacity of spike programming at cerebellar Purkinje neurons.     

用鱼血清转氨酶监测水污染的研究

以三硝基甲苯(INT)、六六六、滴滴涕(DDT)、对硫磷(E-605)、氯化汞分别进行白鲢鱼种的急性致毒实验,与对照组相比,鱼血清谷草转氨酶活性显著增加;对硫磷还引起血清谷丙转氨酶活性的升高。血清转氨酶活性增加的程度与氯化汞浓度相关。不同种类的我国淡水鲤科鱼类、不同鱼龄、不同水体以及短期饥饿、惊扰及网箱饲养对血清转氨酶活性没有影响,但水温升高或溶氧低于1ppm会使鱼血清谷草转氨酶活性升高。水温与鱼血清谷草转氨酶活性有相关性。       

New mechanism of nerve injury in Alzheimer’s disease: β‐amyloid‐induced neuronal pyroptosis

The present study was designed to investigate the role of β‐amyloid (Aβ_1‐42) in inducing neuronal pyroptosis and its mechanism. Mice cortical neurons (MCNs) were used in this study, LPS + Nigericin was used to induce pyroptosis in MCNs (positive control group), and Aβ_1‐42 was used to interfere with MCNs. In addition, propidium iodide (PI) staining was used to examine cell permeability, lactate dehydrogenase (LDH) release assay was employed to detect cytotoxicity, immunofluorescence (IF) staining was used to investigate the expression level of the key protein GSDMD, Western blot was performed to detect the expression levels of key proteins, and enzyme‐linked immunosorbent assay (ELISA) was utilized to determine the expression levels of inflammatory factors in culture medium, including IL‐1β, IL‐18 and TNF‐α. Small interfering RNA (siRNA) was used to silence the mRNA expression of caspase‐1 and GSDMD, and Aβ_1‐42 was used to induce pyroptosis, followed by investigation of the role of caspase‐1‐mediated GSDMD cleavage in pyroptosis. In addition, necrosulfonamide (NSA), an inhibitor of GSDMD oligomerization, was used for pre‐treatment, and Aβ_1‐42 was subsequently used to observe the pyroptosis in MCNs. Finally, AAV9‐siRNA‐caspase‐1 was injected into the tail vein of APP/PS1 double transgenic mice (Alzheimer's disease mice) for caspase‐1 mRNA inhibition, followed by observation of behavioural changes in mice and measurement of the expression of inflammatory factors and pyroptosis‐related protein. As results, Aβ_1‐42 could induce pyroptosis in MCNs, increase cell permeability and enhance LDH release, which were similar to the LPS + Nigericin‐induced pyroptosis. Meanwhile, the expression levels of cellular GSDMD and p30‐GSDMD were up‐regulated, the levels of NLRP3 inflammasome and GSDMD‐cleaved protein caspase‐1 were up‐regulated, and the levels of inflammatory factors in the medium were also up‐regulated. siRNA intervention in caspase‐1 or GSDMD inhibited Aβ_1‐42‐induced pyroptosis, and NSA pre‐treatment also caused the similar inhibitory effects. The behavioural ability of Alzheimer's disease (AD) mice was relieved after the injection of AAV9‐siRNA‐caspase‐1, and the expression of pyroptosis‐related protein in the cortex and hippocampus was down‐regulated. In conclusion, Aβ_1‐42 could induce pyroptosis by GSDMD protein, and NLRP3‐caspase‐1 signalling was an important signal to mediate GSDMD cleavage, which plays an important role in Aβ_1‐42‐induced pyroptosis in neurons. Therefore, GSDMD is expected to be a novel therapeutic target for AD.     

Effects of nutrient levels in surface water and sediment on the growth of the floating-leaved macrophyte Trapa maximowiczii: implication for management of macrophytes in East Bay of Lake Taihu, China

Trapa maximowiczii is a floating-leaved macrophyte common in China. The plant population in East Bay, Lake Taihu, has been expanding rapidly in recent years. In order to better understand the mechanisms controlling the population dynamics in this species, two outdoor experiments were conducted from 9 May to 8 July 2007, evaluating the effect on the growth of T. maximowiczii of different nutrient levels in water column and sediment. Results showed that high concentration of nutrients (nitrogen and phosphorous) in water led to significant increases in rosette diameter and plant dry weight, dry weight of aquatic roots and anchoring roots, but had no effect on plant height or main stem node count. Phosphorus enrichment resulted in increases in plant dry weight and seed number. However, no such difference was observed between the nitrogen enrichment treatment and the control. Sediment fertility had significant effects on plant growth. Plant height, plant dry weight, dry weight of aquatic and anchoring roots, and maximum rosette diameter were significantly greater in high-nutrient sediment than those in low-nutrient sediment. This study suggests that eutrophication of water (especially increasing phosphorus loading) and accumulated nutrients in sediment may be among the causes leading to increasing biomass of the floating-leaved macrophyte T. maximowiczii in East Bay of Lake Taihu.     

c-erbB-2单克隆抗体A18在乳腺癌中表达特性的研究

目的：研究一株自制的c-erbB-2单克隆抗体A18在乳腺癌中表达的特性。方法：应用免疫组织化学SP法、蛋白质印迹分析法和荧光激活的流式细胞分选检测技术检测A18在635例乳腺癌组织、100例癌旁乳腺组织、不表达c-erbB-2的NIH／3T3（鼠成纤维细胞）和NE91（转表皮生长因子受体基因的NR6鼠成纤维面积）细胞株及高表达c-erbB-2的T6－17（转c-erbB-2－基因的NIH／3T3细胞）和SKBR3（人乳腺癌细胞）细胞株中的表达状况,并与市售进口c-erbB-2抗体（MaximBiotech产品）进行了平行对照研究。A18系采用细胞表面区域表位包埋法免疫小鼠制备而成,,结果：A18阳性染色定位于细胞膜,部分伴微弱的细胞浆着色,无明显非特异性染色,A18和进口抗体对NIH／3T3、NE91细胞均呈阴性,T6－17、SKBR3细胞均呈阳性,在乳腺癌组织中,A18的阳性率为60．3％,明显高于癌旁乳腺组织的5．0％,A18与进口同类单抗的阴性、阳性及总符合率分别为84．0％、82．8％及83．2％,与进口同类多抗的阴性,阳性及总符合率分别为88．0％、90．2％和89．5％。A1和进口同类单抗与乳腺癌临床病理特征的关系一致。经反复冻融7次或4℃保存10个月A18效价仍保持在3μg/ml。结论：A18特异性强,定位准确,效价高而稳定、可用于临床乳腺癌的检测。     

高强度酒精连续发酵

从多株酒精酵母菌株中筛选出S.cerevisiaeKG作为酒精生产菌株。该菌株具有较好的酒精发酵活力和絮凝性。使用具有细胞循环的连续发酵双罐系统,酒精生产强度达到30.5（g／1.h）。根据该系统的动力学模型,讨论了获得高强度酒精连续发酵的途径。     

Dietary supplementation with docosahexaenoic acid,but not with eicosapentaenoic acid,reduces host resistance to fungal infection in mice

The effect of dietary docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) on host resistance to Paracoccidioides brasiliensis infection was investigated. Mice fed palm oil supplemented with DHA showed reduced antifungal activity in the spleen and liver, as compared with mice fed palm oil or soybean oil without supplementation with DHA. Mice fed DHA-supplemented soybean oil also showed reduced antifungal activity in the liver, but the extent of reduction was less profound. This reduction in antifungal activity was not observed with EPA-supplemented palm or EPA-supplemented soybean oil. These results suggest that two factors, DHA and palm oil in combination, are involved in reducing the host resistance. DHA-enriched palm oil was also responsible for an increase in DHA concentration and a marked decrease in arachidonic acid content in the spleen and liver. However, this group did not show elevated spleen and liver phospholipid hydroperoxide levels compared with the other groups, excluding the possibility that the reduction in antifungal activity observed with DHA-enriched palm oil is due to acceleration of in vivo lipid peroxidation. Greater infection-induced increases in spleen and serum interferon-gamma concentrations were observed in mice fed DHA-enriched palm oil compared with the other groups.