[Effects of exogenous salicylic acid and brassinolide on photosynthesis of cucumber seedlings under low temperature stress.] / æ°´æ¨é ¸å’Œæ²¹èœç´ å† é ¯å¯¹ä½Žæ¸©èƒè¿«ä¸‹é»„ç“œå¹¼è‹—å ‰åˆä½œç”¨çš„å½±å“.

An experiment was conducted to investigate the mechanism of the regulation of salicylic acid (SA) and 2,4-epibrassionolide (EBR) on photosynthesis in cucumber (Cucumis sativa) seedlings under low temperature stress. Taking cucumber cultivar 'Youbo1-5' as material, the seedlings were pre-treated with 1 mmol·L-1 SA or 0.1 µmol·L-1EBR (sprayed once a day), and then were exposed to chilling temperature (10 ℃/5 ℃, PFD 80 µmol·m-2·s-1) after being pre-treated 2 days. The results showed that the growth and net photosynthetic rate (Pn) of cucumber seedlings were decreased under low temperature stress. However, the Pn, maximal photochemical efficiency of PS2 (Fv/Fm), actual photochemical efficiency of PS2 (ΦPS2) and photochemical quenching coefficient (qP) were significantly improved in SA- and EBR-pretreated seedlings, and the increase range of non-photochemical quenching coefficient (NPQ) was decreased. Moreover, the activities of ribulose 1,5-biphosphate carboxylase/oxygenase (Rubisco), sedoheptulose-1,7-bisphosphatase (SBPase), fructose-1,6-bisphosphate aldolase (FBA) and transketolase (TK) were signi-ficantly increased. These findings suggested that SA and EBR improved photosynthesis of cucumber seedlings by promoting the activities of key enzymes and increased low temperature tolerance.

Identifying the potential extracellular electron transfer pathways from a c-type cytochrome network.

Extracellular electron transfer (EET) is the key feature of some bacteria, such as Geobacter sulfurreducens and Shewanella oneidensis. Via EET processes, these bacteria can grow on electrode surfaces and make current output of microbial fuel cells. c-Type cytochromes can be used as carriers to transfer electrons, which play an important role in EET processes. Typically, from the inner (cytoplasmic) membrane through the periplasm to the outer membrane, they could form EET pathways. Recent studies suggest that a group of c-type cytochromes could form a network which extended the well-known EET pathways. We obtained the protein interaction information for all 41 c-type cytochromes in Shewanella oneidensis MR-1, constructed a large-scale protein interaction network, and studied its structural characteristics and functional significance. Centrality analysis has identified the top 10 key proteins of the network, and 7 of them are associated with electricity production in the bacteria, which suggests that the ability of Shewanella oneidensis MR-1 to produce electricity might be derived from the unique structure of the c-type cytochrome network. By modularity analysis, we obtained 5 modules from the network. The subcellular localization study has shown that the proteins in these modules all have diversiform cellular compartments, which reflects their potential to form EET pathways. In particular, combination of protein subcellular localization and operon analysis, the well-known and new candidate EET pathways are obtained from the Mtr-like module, indicating that potential EET pathways could be obtained from such a c-type cytochrome network.

Sequence-based prediction of DNA-binding residues in proteins with conservation and correlation information.

The recognition of DNA-binding residues in proteins is critical to our understanding of the mechanisms of DNA-protein interactions, gene expression, and for guiding drug design. Therefore, a prediction method DNABR (DNA Binding Residues) is proposed for predicting DNA-binding residues in protein sequences using the random forest (RF) classifier with sequence-based features. Two types of novel sequence features are proposed in this study, which reflect the information about the conservation of physicochemical properties of the amino acids, and the correlation of amino acids between different sequence positions in terms of physicochemical properties. The first type of feature uses the evolutionary information combined with the conservation of physicochemical properties of the amino acids while the second reflects the dependency effect of amino acids with regards to polarity charge and hydrophobic properties in the protein sequences. Those two features and an orthogonal binary vector which reflect the characteristics of 20 types of amino acids are used to build the DNABR, a model to predict DNA-binding residues in proteins. The DNABR model achieves a value of 0.6586 for Matthew's correlation coefficient (MCC) and 93.04 percent overall accuracy (ACC) with a68.47 percent sensitivity (SE) and 98.16 percent specificity (SP), respectively. The comparisons with each feature demonstrate that these two novel features contribute most to the improvement in predictive ability. Furthermore, performance comparisons with other approaches clearly show that DNABR has an excellent prediction performance for detecting binding residues in putative DNA-binding protein. The DNABR web-server system is freely available at http://www.cbi.seu.edu.cn/DNABR/.

Ru(II) sensitized lanthanide luminescence: synthesis, photophysical properties, and near-infrared luminescent determination of alpha-fetal protein (AFP).

A series of dinuclear compounds of [Ru(bpy)(2)(tpphz)Ln(TTA)(3)](PF(6))(2) (tpphz = tetrapyrido[3,2-a:2',3'-c:3'',2''-h:3''',4'''-j]phenazine; Ln = Er(III), Nd(III), Yb(III) and Gd(III); TTA = 2-thenoyltrifluoroacetone) have been prepared by attachment of a [Ln(TTA)(3)] fragment at the vacant diimine site of the luminescent mononuclear complex [Ru(bpy)(2)(tpphz)](PF(6))(2). In the solid state, in CH(2)Cl(2) solution and in Tris-HCl buffer solution of these dinuclear complexes Ru-Ln, sensitized near-infrared (NIR) luminescence is observed from Nd and Yb centres following excitation of the d-block unit, which results from the effective Ru → Ln (Ln = Nd, Yb) energy transfer, but no Er-based NIR luminescence is produced. The (3)MLCT (MLCT = metal to ligand charge transfer) emission is partly quenched in the Ru-Nd complex, slightly increased in the Ru-Yb complex, and is not changed in the Ru-Ercomplex. Interestingly, alpha-fetal protein (AFP) tends to decrease the NIR luminescence intensity of the Ru-Nd complex in Tris-HCl buffer solution. A novel NIR luminescent method for the determination of AFP was developed with a linear range of 0.5-18 ng mL(-1), and a detection limit of 0.2 ng mL(-1) based on 3 times the ratio of the signal-to-noise. Considering the attractive features, such as good selectivity, stability and rapidity, the proposed NIR luminescent method provides promising potential for AFP detection in clinical diagnosis and biomedical applications.

[Establishment of BGC-823/pBaBb-puro-MACC1 gastric cancer cell line stably expressing MACC1 and its tumor-related gene expression profiles].

OBJECTIVE: To establish a gastric cancer cell line with stable expression of metastasis-associated in colon cancer 1 (MACC1) and detect the changes in tumor-related gene expression profiles for investigating the possible regulation mechanisms between MACC1 and the differentially expressed genes. METHODS: The full-length MACC1 cDNA was amplified from human embryonic kidney 293FT cells and cloned into the pBaBb-puro vector. The recombinant pBaBb-puro-MACC1 expression vector, after identification with restriction enzyme digestion, was transfected into 293FT cells, and the expression of fluorescent reporter gene was observed. pBaBb-puro-MACC1 vector was transfected into human gastric cancer BGC-823 cell line to establish BGC-823/pBaBb-puro-MACC1 cell line stably expressing MACC1. Quantitative RT-PCR and Western blotting were used to detect MACC1 expression in both BGC-823/pBaBb-puro-MACC1 and control BGC-823 cells. High-throughout cDNA microarray was used to screen the effects of MACC1 on the gene expression profiles of gastric cancer cells. RESULTS: The recombinant pBaBb-puro-MACC1 plasmid was successfully constructed and verified by PCR and sequencing. BGC-823/pBaBb-puro-MACC1 cells showed significantly increased MACC1 mRNA expression as compared with the control cells. The results of cDNA microarray identified 33 up-regulated and 24 down-regulated genes in the cells after MACC1 transfection involved were in various cellular functions. CONCLUSION: The established BGC-823/pBaBb-puro-MACC1 gastric cancer cell line show some important molecular changes caused by MACC1.

[Effect of glypican-3 on the proliferation of human hepatoma cell line MHCC97-L in vitro].

OBJECTIVE: To construct glypican-3 (GPC3)-green fluorescent protein eukaryotic expression vector pEGFP-c3-GPC3, and analyze the effect of GPC3 on the proliferation of human hepatoma cell line MHCC-97L. METHODS: The eukaryotic expression vector pEGFP-c3-GPC3 was constructed with recombinant DNA technique and transfected into MHCC-97L cells via Lipofectamine 2000. The cells stably expressing GPC3 were screened by flow cytometry and G418. The mRNA expression of GPC3 was detected by RT-QPCR method, and the protein expression by Western blotting and fluorescence microscope. The effect of GPC3 gene on the growth of the cells was examined by MTT assay. RESULTS: Restriction endonuclease analysis and DNA sequencing verified correct construction of the recombinant plasmid. The green fluorescence was detected in the transfected MHCC-97L cells under fluorescence microscope. RT-QPCR and Western blotting both confirmed successful expression of GPC3 in MHCC-97L cells. The growth curve showed a significant acceleration of the proliferation of the transfected MHCC97-Lsol;GPC3 cells as compared with MHCC97-L and MHCC97-L/C3 cells (P<0.001). CONCLUSION: We have successfully constructed the eukaryotic expression vector pEGFR-c3-GPC3, which allows stable GPC3 expression in MHCC97-L/GPC3 cells. The upregulation of GPC3 expression can stimulate the growth of hepatoma cell line MHCC97-L in vitro.

KRAS and PIK3CA but not BRAF genes are frequently mutated in Chinese cholangiocarcinoma patients.

Cholangiocarcinoma (CCA) is a rare but lethal malignancy arising from the biliary tract epithelium. It has a poor prognosis largely due to the difficulties of early diagnosis and the lack of effective therapies. It is thus imperative to develop new and effective treatments for CCA, which depends heavily on the mechanistic understanding of the disease. Previous studies have suggested that somatic mutations in KRAS, BRAF, and PIK3CA genes are frequently found in several types of human cancers including colon, breast, and lung carcinomas as well as CCA. Yet, the frequency and the involvement of these oncogenic mutations in CCA in Chinese population have not been investigated. In this study, we evaluated the hotspot mutations of KRAS, BRAF, and PIK3CA genes in 34 Chinese CCA patients. Sequencing analysis revealed 13 (38.2%) and 11 (32.4%) patients bearing KRAS and PIK3CA mutations, in which two (5.9%) of them harbored both KRAS and PIK3CA mutations. Surprisingly, no BRAF mutation was detected in all 34 CCA samples. Our findings indicate that somatic mutations in KRAS and PIK3CA but not BRAF oncogenes are closely associated with the development of CCA in Chinese population and provide new potential targets for future therapeutic treatments of the disease.

Retrospective study of photodynamic therapy vs photodynamic therapy combined with chemotherapy and chemotherapy alone on advanced esophageal cancer.

OBJECTIVE: To compare the short-term curative effect of photodynamic therapy (PDT), PDT combined with chemotherapy and chemotherapy alone on the advanced esophageal cancer patients. METHODS: Retrospective analysis of 90 patients of esophageal cancer underwent PDT, PDT combined with chemotherapy and chemotherapy alone from 2004 to 2007 (stages III-IV), including 27 cases received PDT alone, 33 cases received PDT combined with chemotherapy and 30 cases chemotherapy alone. The enrolled patients were treated with intravenous administration of Photofrin as the photosensitizer at a dose of 2mg/kg. 630 nm laser irradiation was performed through optical fiber that passed through the biopsy channel of a flexible endoscope after 48 h. Two days later, the necrotic tissue was removed, and the primary sites and other newly identified lesions were subjected to a second irradiation and then the residual necrotic tissue was removed according to the patients' condition. Electronic endoscopy was performed to observe the effectiveness on tumor after 1 month. In PDT combined with chemotherapy group, chemotherapy regimen was 5-FU and DDP, administered 4 cycles after PDT and chemotherapy alone group only chemotherapy regimen 5-FU and DDP for four cycles. All the 90 patients were followed up for 2 years. RESULTS: Symptomatic palliation rate of the PDT alone group, the complex treatment group and chemotherapy alone group was 85.2%, 93.9% and 60.0%, respectively, and effective rate under endoscopy was 85.2%, 90.9% and 63.3%, respectively, there is no statistically significant difference; the survival rate of 2 years was 29.6%, 54.5% and 16.7%, respectively, and medium survival time is longer (III stages 13 m, 22 m, 10 m; IV stages 7 m, 5m, 4m), there is statistically significant difference (p=0.046). CONCLUSION: PDT combined with chemotherapy for the advanced esophageal cancer is superior to PDT alone and chemotherapy alone.

[Inhibitory effect of SHP-1 gene transfer on the proliferation of breast cancer cell line MDA-MB-231].

OBJECTIVE: To observe SHP-1 protein expression in breast cancer cell line MDA-MB-231 before and after SHP-1 gene transfer and its effect on the proliferation of MDA-MB-231 cells. METHODS: The eukaryotic expression vector pEGFP-C3-SHP-1 was constructed and transfected into breast cancer cell line MDA-MB-231 via Lipofectamine 2000, and the positive clones were selected using G418. SHP-1 expression in MDA-MB-231 cells was detected with immunocytochemistry and Western blotting, and the cell growth curve was observed using MTT assay. RESULTS: SHP-1 was highly expressed in transfected MDA-MB-231 cells, whose proliferation was significantly inhibited (P<0.05). CONCLUSION: SHP-1 gene transfer into MDA-MB-231 cells results in inhibition of the cell proliferation.

PAK4 kinase is essential for embryonic viability and for proper neuronal development.

The serine/threonine kinase PAK4 is a target for the Rho GTPase Cdc42 and has been shown to regulate cell morphology and cytoskeletal organization in mammalian cells. To examine the physiological and developmental functions of PAK4, we have disrupted the PAK4 gene in mice. The absence of PAK4 led to lethality by embryonic day 11.5, a result most likely due to a defect in the fetal heart. Striking abnormalities were also evident in the nervous systems of PAK4-deficient embryos. These embryos had dramatic defects in neuronal development and axonal outgrowth. In particular, spinal cord motor neurons and interneurons failed to differentiate and migrate to their proper positions. This is probably related to the role for PAK4 in the regulation of cytoskeletal organization and cell and/or extracellular matrix adhesion. PAK4-null embryos also had defects in proper folding of the caudal portion of the neural tube, suggesting an important role for PAK4 in neural tube development.