甘草水溶物诱导MGC-803细胞凋亡中胞内Ca2+、pH与线粒体△ψm的变化

细胞凋亡时发生染色质凝聚、DNA呈梯状片段化、胞体皱缩、质膜起泡、形成凋亡小体等典型的形态和生化变化,并受凋亡信号系统激活所导致的细胞内一系列酶的活性以及凋亡相关基因表达的变化调控.近年来的研究表明,细胞内Ca2 、pH、线粒体膜电位(△Ψm)等生物物理性状的改变与细胞凋亡信号系统的调控有密切的关系,甚至是决定性的因素.糖皮质激素能非常有效地诱导胸腺细胞发生凋亡,已证实在这典型的凋亡过程中,细胞内Ca2 浓度变化是至为重要的环节,处理细胞早期就可见到细胞内Ca2 的持续升高,然后是DNA片段化.尽管也有文献报道在无Ca2 基质…     

晋西北3个树种抗旱性指数的研究

根据对海红、刺槐和柠条的ＰＶ曲线主要水分参数的测定,进行了抗旱性指数季节变化和种间排序分析。结果表明,树种的抗旱性随着年生长发育节律和环境水分条件而改变,其抗早性生长季初最弱,夏季高温干早阶段增强,秋季降雨峰期减弱,生长季末最强或很强。柠条的抗旱性与海红很接近。这对黄土高原地区果树和饲料的开发与水土保持树种的推广有重要意义。     

Salicylic acid differently impacts ethylene and polyamine synthesis in the glycophyte Solanum lycopersicum and the wild‐related halophyte Solanum chilense exposed to mild salt stress

This study aimed to determine the effects of exogenous application of salicylic acid (SA) on the toxic effects of salt in relation to ethylene and polyamine synthesis, and to correlate these traits with the expression of genes involved in ethylene and polyamine metabolism in two tomato species differing in their sensitivity to salt stress, Solanum lycopersicum cv Ailsa Craig and its wild salt‐resistant relative Solanum chilense. In S. chilense, treatment with 125 mM NaCl improved plant growth, increased production of ethylene, endogenous salicylic acid and spermine. The production was related to a modification of expression of genes involved in ethylene and polyamine metabolism. In contrast, salinity decreased plant growth in S. lycopersicum without affecting endogenous ethylene, salicylic or polyamine concentrations. Exogenous application of salicylic acid at 0.01 mM enhanced shoot growth in both species and affected ethylene and polyamine production in S. chilense. Concomitant application of NaCl and salicylic acid improved osmotic adjustment, thus suggesting that salt and SA may act in synergy on osmolyte synthesis. However, the beneficial impact of exogenous application of salicylic acid was mitigated by salt stress since NaCl impaired endogenous SA accumulation in the shoot and salicylic acid did not improve plant growth in salt‐treated plants. Our results thus revealed that both species respond differently to salinity and that salicylic acid, ethylene and polyamine metabolisms are involved in salt resistance in S. chilense.     

Granulocyte-macrophage colony-stimulating factor binding sites and oxidative metabolism in human granulocytes

We investigated the interaction between GM-CSF and its receptor on human granulocytes and on several human tumor cell lines. Specific high-affinity binding for GM-CSF was characterized by Scatchard plot analysis. The specific radioactivity of the 125I-labeled derivative of rH. GM-CSF was determined by self-displacement analysis and calculated to be 30 microCi/micrograms. The maximum concentration of binding sites (B max) in granulocytes was 40 fmol/mg protein (2,200 molecules GM-CSF bound/cell) and the dissociation constant (KD) was 0.42 nM. No binding sites for GM-CSF were found in two lung cancer cell lines, SCLC-16HV and NCI-N417 or in the urinary bladder carcinoma cell line 5637, whereas the promyelocytic leukemia cell line HL60 was positive for GM-CSF binding. Time course experiments showed maximum binding of GM-CSF in granulocytes after an incubation period of 60 min and a decrease in binding after an incubation period of 2 h. In parallel, we found a maximum biological signal when granulocytes were preincubated for 90 min with GM-CSF, and a decrease after an incubation time of 120 min. Preincubation of the cells with rH. GM-CSF induced an enhancement of the production of activated oxygen species by the cells in response to PMA.     

Monoclonal antibodies to cyclodextrin-glycosyltransferase from Bacillus macerans]

Cyclodextrin glycosyltransferase (CGTase, EC 2.4.1.19) was isolated from the cell-free culture medium of Bacillus macerans strain BKMB-506. The purified enzyme was used to immunize BALB/c mice. Polyclonal antibodies (PAbs) and 15 hybridoma cells producing monoclonal antibodies (MAbs) against CGTase were obtained. The properties of MAbs were studied using ELISA and immunoblotting. A method for detecting small amounts of CGTase was developed. The interactions of PAbs and MAbs with CGTase of Bac. circulans var. alkalophilis were investigated.     

HOMER2, a Stereociliary Scaffolding Protein,Is Essential for Normal Hearing in Humans and Mice

Hereditary hearing loss is a clinically and genetically heterogeneous disorder. More than 80 genes have been implicated to date, and with the advent of targeted genomic enrichment and massively parallel sequencing (TGE+MPS) the rate of novel deafness-gene identification has accelerated. Here we report a family segregating post-lingual progressive autosomal dominant non-syndromic hearing loss (ADNSHL). After first excluding plausible variants in known deafness-causing genes using TGE+MPS, we completed whole exome sequencing in three hearing-impaired family members. Only a single variant, p.Arg185Pro in HOMER2, segregated with the hearing-loss phenotype in the extended family. This amino acid change alters a highly conserved residue in the coiled-coil domain of HOMER2 that is essential for protein multimerization and the HOMER2-CDC42 interaction. As a scaffolding protein, HOMER2 is involved in intracellular calcium homeostasis and cytoskeletal organization. Consistent with this function, we found robust expression in stereocilia of hair cells in the murine inner ear and observed that over-expression of mutant p.Pro185 HOMER2 mRNA causes anatomical changes of the inner ear and neuromasts in zebrafish embryos. Furthermore, mouse mutants homozygous for the targeted deletion of Homer2 present with early-onset rapidly progressive hearing loss. These data provide compelling evidence that HOMER2 is required for normal hearing and that its sequence alteration in humans leads to ADNSHL through a dominant-negative mode of action.     

Spectroscopic characterization of the artificial Siderophore pyridinochelin

Siderophores play a very important role in the uptake process of iron by bacteria. Due to the so-called active transport the uptake of siderophores by bacteria is very specific, which makes the use of siderophores as effective shuttles for antibiotics in the treatment of infections and other diseases caused by bacteria highly attractive. In order to further investigate the transport and incorporation of siderophores into the bacteria cells, distinct molecular probes are needed. Especially artificial siderophores, that show a specific intrinsic fluorescence, are highly attractive for such monitoring purposes. A promising candidate of such a fluorescent artificial siderophore is bis-2,3-dihydroxybenzoyl-2,6-dimethylamino-pyridine (pyridinochelin, PY). The fluorescence properties of PY were investigated in different solvents and in the presence of different metal ions. It was found that PY in its free form shows a complex fluorescence behavior. In methanol a clear dual fluorescence is observed. In aqueous solution intermolecular interactions with water molecules are determining the intrinsic fluorescence. Upon complexation with metal ions (Me3+ = Eu3+, Tb3+, Al3+, Fe3+) the fluorescence characteristics changed. The fluorescence quantum yield of PY decreased upon addition of Me3+--except for Al3+, which showed no fluorescence quenching. The fluorescence decay of PY loaded with metal ions showed a nicely mono-exponential fluorescence decay, which was in contrast to PY in the absence of metal ions. This drastic change in the fluorescence properties of PY upon metal ion complexation makes PY highly attractive as a fluorescence probe for the investigation of siderophore action and siderophore-mediated transport processes.     

Lipid Peroxidation and Antioxidant System in the Tumor and in the Blood of Patients with Nasopharyngeal Carcinoma

Reactive oxygen species play a key role in cancer development by inducing and maintaining the oncogenic phenotypes of cancer cells. In this study, we examined lipid peroxidation and antioxidant enzymes activities in the blood and in the tumor of nasopharyngeal carcinoma patients. Plasma malondialdehyde, conjugated dienes, erythrocytes catalase, and superoxide dismutase activities have been measured in 30 untreated nasopharyngeal carcinoma patients and 30 controls on one hand. On the other hand, tumor malondialdehyde level, catalase, and superoxide dismutase activities have been measured in five nasopharyngeal carcinoma patients and compared with four controls. The lipid peroxidation was confirmed in the plasma by the high levels of malondialdehyde and conjugated dienes (p?<?0.001, respectively). Additionally, significantly higher concentrations of malondialdehyde were found in biopsies compared to the control group (p?<?0.001). In erythrocytes, superoxide dismutase activity was higher in patients than in controls (p?<?0.05), while it was unchanged in the tumor (p?>?0.05). Both erythrocytes and tumor catalase activities were significantly lower in patients than in controls (p?<?0.001, respectively). Statistical studies have shown a positive correlation between malondialdehyde level and IgA antibodies level against Epstein–Barr virus capsid antigen (p?<?0.05). In conclusion, we reported the presence of an oxidative stress in the blood and in the biopsies of nasopharyngeal carcinoma patients where Epstein–Barr virus seems to play a role.