Effects of Aluminum on Immune Functions of Cultured Splenic T and B Lymphocytes in Rats

The effects of Aluminum (Al) exposure on immune functions of cultured splenic T and B lymphocytes of rats were studied. The lymphocytes were isolated from spleen of healthy male Wistar rats weighing 110-120 g. The cultured cells in RPMI-1640 medium were exposed to 0 (control group), 0.035 (low-dose group), 0.07 (medial-dose group), and 0.14 (high-dose group) mg/mL Al(3+) as aluminum trichloride (AlCl(3)) in an incubator under 5% CO(2) at 37°C for 24 h. The T and B lymphocyte proliferation was measured with a tetrazolium dye colorimetric assay. The levels of interleukin (IL)-2, IL-6, and tumor necrosis factor (TNF)-α were determined by iodine [(125)I] IL-2, IL-6, and TNF-α radioimmunoassay kits, respectively. The proportions of CD3(+), CD4(+), and CD8(+) T lymphocytes were measured with a flow cytometer. The results showed that the T and B lymphocyte proliferation, the levels of IL-2, IL-6, TNF-α, the proportions of CD3(+) and CD4(+) T lymphocytes, and the ratio of CD4(+)/CD8(+) T lymphocytes were lowered by Al treatments, while the proportion of CD8(+) T lymphocytes was increased. These findings indicate that Al exposure can inhibit the immune functions of splenic T and B lymphocytes of rats in vitro.     

Secretion expression of recombinant glucagon inEscherichia coli

A novel approach for the preparation of recombinant human glucagon was described. An expression vector pAGluT, containing phoA promoter, phoA signal peptide and glucagon gene, was constructed by means of genetic engineering.Escherichia coli strain YK537 was transformed with pAGluT. High-level secretory expression of recombinant human glucagon was achieved. The expression yield of recombinant human glucagon was found to be 80 mg/L, approximately 30% of the total proteins in supernatant. The biological activities and the physicochemical properties of the purified recombinant human glucagon were found to be the same as that of native glucagon. In addition, our results suggested that phoA expression system may be suitable for the expression of other small peptides.     

Tyrosinase inhibitory effects and inhibition mechanisms of nobiletin and hesperidin from citrus peel crude extracts

The inhibitory effects of nobiletin and hesperidin from citrus peel crude extracts on tyrosinase diphenolase activity are evaluated. IC₅₀ of nobiletin and hesperidin is 1.49 mM and 16.08 mM, respectively and their inhibition mechanism is competitive type with K_i = 2.82 mM and noncompetitive with K_i = 9.16 mM, respectively. Crude extracts from citrus peel (C. unshiu Marc.) were extracted with 95% ethanol and fractionated by petroleum ether (PCPE). The ethanol phase (ECPE) was further desorbed from macroporous adsorption resin (FGRE). Their IC₅₀ values were 8.09 mg/mL, 7.53 mg/mL and 4.80 mg/mL, respectively. Their inhibition on melanogenesis in B16 mouse melanoma cells was also evaluated. FGRE showed a significant inhibition (42.5% at 31.25 μg/mL, p < 0.01) while hesperidin showed almost no inhibition. Nobiletin and PCPE give efficacious antiproliferation effects on B16 mouse melanoma cell with IC₅₀ values 88.6 μM and 62.96 μg/mL, respectively, by the MTT test. Hesperidin and other crude extracts showed very low cytotoxity to the B16 cell.     

N-Acyl-homoserine lactones and autoinducer-2-mediated quorum sensing during wastewater treatment

Applied Microbiology and Biotechnology - Bacteria can coordinate and synchronize activities through a cell density-dependent regulatory mechanism called quorum sensing (QS). Bacteria can measure...     

Effects of Aluminum Exposure on the Adherence, Chemotaxis, and Phagocytosis Capacity of Peritoneal Macrophages in Rats

To investigate the effects of aluminum (Al) exposure on peritoneal macrophages of Wistar rats, four groups of ten rats each were orally exposed to 0, 13, 26, and 52?mg?kg(-1) Al(3+) in form of aluminum trichloride (AlCl(3)) in drinking water for 120?days. At the end of the experimental period, the Al concentration in serum, the adherence, chemotaxis, and phagocytosis capacity of peritoneal macrophages were determined. The results showed that the Al concentration in serum significantly increased in a dose-dependent manner; the adherence, chemotaxis, and phagocytosis capacity of peritoneal macrophages decreased with the increase of Al dose, and present a dose-effective relationship. Further, they were significantly lower in the high-dose groups (P?相似文献   

岷江上游景观格局及生态水文特征分析

基于1994年岷江上游TM遥感影像分类,结合6个不同集水区1992、1993、1995年植被生长季降雨、径流及同期NOAA/AVHRR的N DVI数据,构建了植被保水指数作为表征植被生态水文功能分析的指标。并用此对岷江上游6个不同集水区景观格局与生态水文特征进行分析。结果表明:不同集水区植被组成及景观结构有显著差异;不同集水区植被保蓄降雨能力即保水指数有明显差异;不同集水区景观结构指数与保水指数之间具有很高相关性,其中边界密度、多样性指数与保水指数呈负相关,聚集度指数与保水指数呈正相关。保水指数的构建对植被建设具有一定的科学意义