Construction and secretory expression of beta-galactosidase gene from Lactobacillus bulgaricus in Lactococcus lactis / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>This study is to examine the secretion effects of beta-galactosidase in Lactococcus lactis.</p><p><b>METHODS</b>The usp45 and beta-galactosidase genes were cloned and inserted into plasmid pMG36e to obtain the recombinant plasmid pMG36e-usp-lacZ. This recombinant plasmid was transformed into both Escherichia coli DH5alpha and L. lactis MG1363. The enzyme activity, gene sequencing, SDS-PAGE and hereditary stability were assessed and studied.</p><p><b>RESULTS</b>The lacZ gene inserted into plasmids pMG36e-usp-lacZ was 99.37% similar to the GenBank sequence, and SDS-PAGE revealed an evident idio-strap at 116 KDa between L. lactis MG1363/pMG36e-usp-lacZ in both supernatant and cell samples. Beta-Galactosidase activity measured 0.225 U/mL in L. lactis pMG36e-usp-lacZ transformants, and its secretion rate was 10%. The plasmid pMG36e-usp-lacZ appeared more stable in MG1363.</p><p><b>CONCLUSION</b>The authors concluded that these new recombinant bacteria well expressed and secreted beta-galactosidase, indicating that the beta-galactosidase expression system was successfully constructed, and this might provide a new solution for management of lactose intolerance specifically and promote the use of gene-modified organisms as part of the food-grade plasmid in general.</p>

Ginsenoside Rb1, a panoxadiol saponin against oxidative damage and renal interstitial fibrosis in rats with unilateral ureteral obstruction / 中国结合医学杂志

<p><b>OBJECTIVE</b>To investigate the possible protective effect and mechanism of ginsenoside Rb1 against oxidative damage and renal interstitial fibrosis on rats with unilateral ureteral obstruction (UUO).</p><p><b>METHODS</b>In total, 80 male rats were randomly divided into 4 groups, 20 in each group: the sham operated group (SOR), UUO group, UUO with ginsenoside Rb1 treatment group (treated with intraperitoneal injection of 50 mg/ kg daily) and UUO with Losartan treatment group (as the positive control, treated with 20 mg/kg by gastrogavage per day). The rats were randomly sacrificed on day 3, 7 and 14 after surgery, respectively. The histopathologic changes of renal interstitial tissues were observed with Masson staining. The mRNA of transforming growth factor beta 1 (TGF-beta 1), collagen I and fibronectin were reversed transcribed and quantified by Real-time PCR. Enzyme-linked immunosorbent assay was used to quantitatively detect TGF-beta 1 and 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels. P47phox protein expression was assessed by immunohistochemistry and Western blot analysis.</p><p><b>RESULTS</b>In the UUO model, the obstructed kidney showed typical features of progressive renal tubulointerstitial fibrosis, and the levels of TGF-beta1, collagen I and fibronectin increased (P<0.05). As compared with the UUO group, ginsennoside Rb1 significantly inhibited the interstitial fibrosis including tubular injury and collagen deposition, and decreased the levels of TGF-beta1 (P<0.05). Ginsenoside Rb1 also inhibited the heme oxygenase (HO-1) and 8-OHdG, two markers of oxidative stress (P<0.05). Moreover, ginsenoside Rb1 suppressed the expression of p47phox, a subunit of nicotinamide adeninedinucleotide phosphate (NADPH) oxidase (P<0.05).</p><p><b>CONCLUSION</b>Ginsenoside Rb1 can obviously inhibit renal interstitial fibrosis in rats with UUO, its mechanism possibly via against the oxidative damage and suppressing TGF-beta1 expression.</p>

Development of a universal primers PCR-coupled liquid bead array to detect biothreat bacteria / 中华预防医学杂志

<p><b>OBJECTIVE</b>To develop a fast, high-throughput screening method with suspension array technique for simultaneous detection of biothreat bacteria.</p><p><b>METHODS</b>16 S rDNA universal primers for Bacillus anthracis, Francisella tularensis, Yersinia pestis, Brucella spp.and Burkholderia pseudomallei were selected to amplify corresponding regions and the genus-specific or species-specific probes were designed. After amplification of chromosomal DNA by 16 S rDNA primers 341A and 519B, the PCR products were detected by suspension array technique. The sensitivity, specificity, reproducibility and detection power were also analyzed.</p><p><b>RESULTS</b>After PCR amplification by 16 S rDNA primers and specific probe hybridization, the target microorganisms could be identified at genus level, cross reaction was recognized in the same genus. The detection sensitivity of the assay was 1.5 pg/microl (Burkholderia pseudomallei), 20 pg/microl (Brucella spp.), 7 pg/microl (Bacillus anthracis), 0.1 pg/microl (Francisella tularensis), and 1.1 pg/microl (Yersinia pestis), respectively. The coefficient of variation for 15 test of different probes was ranged from 5.18% to 17.88%, it showed good reproducibility. The assay could correctly identify Bacillus anthracis and Yersinia pestis strains in simulated white powder samples.</p><p><b>CONCLUSION</b>The suspension array technique could be served as an opening screening method for biothreat bacteria rapid detection.</p>

Non-fusion and fusion expression of beta-galactosidase from Lactobacillus bulgaricus in Lactococcus lactis / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To construct four recombinant Lactococcus lactis strains exhibiting high beta-galactosidase activity in fusion or non-fusion ways, and to study the influence factors for their protein expression and secretion.</p><p><b>METHODS</b>The gene fragments encoding beta-galactosidase from two strains of Lactobacillus bulgaricus, wch9901 isolated from yogurt and 1.1480 purchased from the Chinese Academy of Sciences, were amplified and inserted into lactococcal expression vector pMG36e. For fusion expression, the open reading frame of the beta-galactosidase gene was amplified, while for non-fusion expression, the open reading frame of the beta-galactosidase gene was amplified with its native Shine-Dalgarno sequence upstream. The start codon of the beta-galactosidase gene partially overlapped with the stop codon of vector origin open reading frame. Then, the recombinant plasmids were transformed into Escherichia coli DH5 alpha and Lactococcus lactis subsp. lactis MG1363 and confirmed by determining beta-galactosidase activities.</p><p><b>RESULTS</b>The non-fusion expression plasmids showed a significantly higher beta-galactosidase activity in transformed strains than the fusion expression plasmids. The highest enzyme activity was observed in Lactococcus lactis transformed with the non-fusion expression plasmids which were inserted into the beta-galactosidase gene from Lactobacillus bulgaricus wch9901. The beta-galactosidase activity was 2.75 times as high as that of the native counterpart. In addition, beta-galactosidase expressed by recombinant plasmids in Lactococcus lactis could be secreted into the culture medium. The highest secretion rate (27.1%) was observed when the culture medium contained 20 g/L of lactose.</p><p><b>CONCLUSION</b>Different properties of the native bacteria may have some effects on the protein expression of recombinant plasmids. Non-fusion expression shows a higher enzyme activity in host bacteria. There may be a host-related weak secretion signal peptide gene within the structure gene of Lb. bulgaricus beta-galactosidase, and its translation product may introduce the enzyme secretion out of cells in special hosts.</p>

Ginsenoside R(g1) inhibit transdifferentiation in rat renal tubular epethelial cells induced by TGF-beta1 / 中国中药杂志

<p><b>OBJECTIVE</b>To investigate the effects of ginsenoside R(g1) on the transdifferentiation of rat renal tubular epethelial cells induced by transforming growth factor-beta1, (TGF-beta1).</p><p><b>METHOD</b>Cultured normal rat renal tubular epethelial cells (NRK-52E) were divided into control group, TGF-beta1-induced group and treated with ginsenoside R(g1) at different concentration (10, 20, 40 mg x L(-1)) group. The morphology of tubular epithelial-myofibroblast transdifferentiation induced by TGF-beta1 was observed through light microscope. alpha-SMA and E-cadherin protein expression were assessed by immunohistochemistry and western blot analyses. alpha-SMA, collagen I and and fibronectin gene expression were assessed by real-time quantitative chain reaction. Enzyme-linked immunosorbent assay was used to quantitatively detect collagen I and fibronectin in the supernatant.</p><p><b>RESULT</b>10 mg x L(-1) TGF-beta1 could induce the transdifferentiation of tubular epithelial myofibroblast, showing fibroblast-like in morphology, with significantly enhanced expression of alpha-SMA, depressed expression of E-cadherin and increased secretion of fibronectin and collagen I (P < 0.05). Compared to TGF-beta1-induced group, ginsenoside R(g1) partly abrogated the alpha-SMA expression and E-cadherin depression triggered by TGF-beta1 in tubular epithelial cells in a dose-dependent manner (P < 0.05). Meanhile, ginsenoside R(g1) blocked morphologic transformation of tubular epithelial cells and decreased levels of collagen I and fibronectin (P < 0.05).</p><p><b>CONCLUSION</b>Ginsenoside R(g1) could inhibit TGF-beta1 induced the tubular epithelial-myofibroblast transdifferentiation and decreased levels of collagen I and fibronectin in NRK52E.</p>

Comparison of susceptibilities of M. tuberculosis H37Ra and M. chelonei subsp. abscessus to disinfectants / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To determine the susceptibilities of M. tuberculosis H37Ra and M. chelonei subsp. absecessus to several frequently-used disinfectants and to evaluate the practicability of surrogating M. tuberculosis by the latter.</p><p><b>METHODS</b>A suspension quantitative bactericidal test was set up in accordance with Chinese Technique Standard for Disinfection to evaluate the susceptibility of each mycobacteria strain to each selected disinfectant. Killing log value was used as criterion in comparing the susceptibility to disinfectants between the two strains.</p><p><b>RESULTS</b>M. chelonei subsp. abscessus was more resistant to chlorine disinfectant than M. tuberculosis while the two strains were similarly resistant to iodophor disinfectant, peracetic acid, alcohol and glutaraldehyde disinfectant.</p><p><b>CONCLUSION</b>M. chelonei subsp. abscessus has the potential to surrogate M. tuberculosis in evaluating mycobactericidal efficacies of disinfectants.</p>