Dynamic expression of insulin-like growth factor-binding proteins during chondrogenesis / 中华整形外科杂志

Objective@#To clarify the status of proliferation and differentiation of RCJ3.1C5.18 cells in chondrogenesis and explore insulin-like growth factor binding proteins (Igfbps) gene expression profile during the process. The results provided a research foundation for understanding the role of Igfbps in chondrogenesis.@*Methods@#Fetal rat derived mesenchymal chondrogenic cell line RCJ3.1C5.18 was used, which progresses spontaneously to differentiated growth plate chondrocytes. The proliferation and differentiation status of cells were determined by cell staining, real-time PCR and Muse™ Cell Analyzer at days 1, 4, 7 and 10 of culture respectively. Igfbps gene expression was assessed by real-time PCR.@*Results@#In the early period (1-4 days), cells proliferated rapidly and the expression of chondrocytes marker genes, such as typeⅡ collagen, SRY-box 9 and aggrecan increased gradually. Igfbp4 and Igfbp6 gene expression paralleled the expression of chondrocytes marker genes. On days 7-10 of culture, cells viability decreased and gradually developed hypertrophic-like and osteogenic-like characteristics, which was confirmed by specific staining and gene expression of alkaline phosphatase, matrix metallopeptidase 13.Igfbp1, Igfbp3 and Igfbp5 mRNA levels were up regulated gradually at this stage.@*Conclusions@#The status of proliferation and differentiation of cells are different in the process of chondrogenesis. Changes in Igfbp gene expression are associated with chondrocyte differentiation, suggesting that they have different role during chondrocyte proliferation and differentiation.

Overpression of miR-29b suppresses the proliferation and induces apoptosis of cholangiocarcinoma cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the expression of miR-29b in cholangiocarcinoma and explore its effects on cell proliferation and apoptosis of cholangiocarcinoma cells.</p><p><b>METHODS</b>Real-time PCR was used to detect the expression of miR-29b in cholangiocarcinoma cells line QBC939 and cholangiocarcinoma tissues. The lentiviral vector LV-hsa-miR-29b and blank vector were constructed to infect QBC939 cells. MTT assay and cell clone formation assay were performed to assess the changes in the cell proliferation and clone formation, respectively; flow cytometry was employed to evaluate the effect of miR-29b overexpression on cell cycle and apoptosis.</p><p><b>RESULTS</b>The expression of miR-29b was significantly down-regulated in QBC939 cells and cholangiocarcinoma tissues as compared with H-69 cells and normal tissues ( < 0.01). Compared with the blank vector, the lentiviral vector LV-hsa-miR-29b caused significantly increased expression of miR-29b in QBC939 cells ( < 0.01), which exhibited suppressed cell proliferation and clone formation ( < 0.01 or 0.05), cell cycle arrest at the S phase ( < 0.05), and significantly increased cell apoptosis ( < 0.01).</p><p><b>CONCLUSIONS</b>As a tumor-suppressing miRNA, miR-29b is down-regulated in cholangiocarcinoma, and its overexpression can suppress the proliferation and induce apoptosis of cholangiocarcinoma cells.</p>

Effect of ctpxa1 gene deletion in Candida tropicalis on long chain dicarboxylic acid accumulation / 生物工程学报

Candida tropicalis uses alkanes and fatty acids to produce long chain dicarboxylic acids. However, the yield can be affected by β-oxidation in peroxisomes. Pxa1p was a membrane protein of Saccharomyces cerevisiae peroxisomes. Pxa1p and Pxa2p form a dimer that is involved in transporting of long chain fatty acids into peroxisomes, but the similar transporting system of Candida tropicalis has not yet been reported. In this study, a ctpxa1 gene deletion strain named C. tropicalis 1798-pxa1 was constructed by homologous single exchange method using PCR fragment. The expression of ctpxa1 gene in C. tropicalis 1798, C. tropicalis 1798-pxa1 was detected by semi-quantitative RT-PCR, and the ratio of gray value was 2.03, implying that the expression of ctpxa1 in C. tropicalis 1798-pxa1 was weakened. After 144 h fermentation, the dodecanedioic acid production of C. tropicalis 1798-pxa1 was increased 94.3% than the former strain, the maximum yield was 10.3 g/L.

Expression of Arabidopsis thaliana thioesterase gene in Pichia pastoris / 生物工程学报

Thioesterase catalyzes the hydrolysis of acyl-ACP and saturated fatty acyl chain. It plays a key role in the accumulation of medium chain fatty acids in vivo. In this study, to construct an engineering strain to produce MCFAs, the Arabidopsis acyl-ACP thioesterase gene AtFatA was amplified by PCR from cDNA of arabidopsis and double digested by EcoR I/Xba I, then linked to the plasmid digested with same enzymes to get the recombinant plasmid pPICZaA-AtFatA. We transformed the gene into Pichia pastoris GS115 by electroporation and screened positive colonies by YPD medium with Zeocin. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) results showed that the recombinant enzyme had a molecular of 45 kDa band which was consistent with the predicted molecular mass and we constructed the expression system of gene AtFatA in fungus for the first time. Under shake-flask conditions, Gas Chromatograph-Mass Spectrometer-computer results indicated that recombinant strain produced 51% more extracellular free MCFAs than the wild and its yield reached 28.7% of all extracellular fatty acids. This figure is 10% higher than the control group. The result provides a new way to produce MCFAs.

Protective effects of Trimetazidine on ischemia-reperfusion injury of fatty liver in rats / 天津医药

Objective To investigate the protective effects of Trimetazidine(TMZ)on the ischemia reperfusion injury (IRI)of fatty liver in autotransplantation model. Methods Fatty liver model was established by feeding high fat diet. Male Wistar rats (n=30) were randomized into three groups;Sham group, TMZ group and Model group. Liver was autotransplanted in both TMZ group and Model group. Serum levels of ALT, SOD, MDA, Bcl-2 and activated Caspase-3 were assessed 6 hours after the operation. The pathological performances of liver were also determined. Results Compared with the Model group, serum levels of ALT,AST, MDA and SOD levels decreased significantly in the TMZ group(P<0.05). Serum level of Bcl-2 was higher while level of activated Caspase-3 was lower in TMZ group than those in Model group(P<0.05). Histo?logical assay and TUNEL staining showed reduced hepatocyte swelling and narrowed sinusoid as well as decreased hepatic apoptosis in TMZ group compared with Model group. Conclusion TMZ can reduce oxidative stress, promote the expression of Bcl-2 and inhibit the activation of Caspase-3, which all contribute to its protective effect on fatty liver with ischemia-re?perfusion injury.

Determination of Au and Ag in Geological Samples by Loaded Polyurethane Foam-Inductively Coupled Plasma-Mass Spectrometry / 分析化学

The relatively high abundance of geochemical elements such as Nb, Zr, Y and other elements shows serious interferences in the determination of trace silver in geochemical samples by inductively coupled plasma-mass spectrometry ( ICP-MS) . Thus it will lead to large deviation in the determination of geochemical samples without separation and enrichment. The traditional emission spectrum or graphite furnace atomic absorption method is only single-element analysis to the silver and with bad sample representativeness. In this study, load diphenylthiourea ( DPTU) foam selective enrichment was used for the separation of Au and Ag from other interfering elements in geological samples, and thiourea liberation-ICP-MS method was developed for the simultaneous determination of Au and Ag. The samples were first decomposed by 1:1 aqua regia. After addition of 50 mL of water, the samples were adsorbed under oscillation for 30 min at 20℃. The detection limits of the Au and Ag were 0. 02 ng/g and 0. 007μg/g, respectively. The proposed method was successfully applied to the determination of Au and Ag in eight national standard materials.