Y Bai

Peking University Health Science Center, Peping, Beijing, China

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Publications (3)8.1 Total impact

  • Y Bai · Z Meng · M Cui · X Zhang · F Chen · J Xiao · L Shen · Y Zhang
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    ABSTRACT: Neural progenitor cells (NPCs) have the potential to survive brain ischemia and participate in neurogenesis after stroke. However, it is not clear how survival responses are initiated in NPCs. Using embryonic mouse NPCs and the in vitro oxygen and glucose deprivation (OGD) model, we found that angiopoietin-1 (Ang1) could prevent NPCs from OGD-induced apoptosis, as evidenced by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling and annexin V labeling. Ang1 significantly elevated tunica intima endothelial kinase 2 (Tie2) autophosphorylation level, suggesting the existence of functional Tie2 receptors on NPCs. NPCs under OGD conditions exhibited reduction of Akt phosphorylation, decrease of the Bcl-2/Bax ratio, activation of caspase-3, cleavage of PARP, and downregulation of beta-catenin and nestin. Ang1 reversed the above changes concomitantly with significant rising of survival rates of NPCs under OGD, but all these effects of Ang1 could be blocked by either soluble extracellular domain of Tie2 Fc fusion protein (sTie2Fc) or the phosphoinositide 3-kinase (PI3K) inhibitor 2-(4-morpholinyl)-8-phenyl-1(4H)-benzopyran-4-one (LY294002). Our findings suggest the existence of an Ang1-Tie2-PI3K signaling axis that is essential in initiation of survival responses in NPCs against cerebral ischemia and hypoxia.
    Neuroscience 06/2009; 160(2):371-81. DOI:10.1016/j.neuroscience.2009.01.076 · 3.33 Impact Factor
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    ABSTRACT: This paper describes optimization of electrotransformation of Mu transposition complexes into Lactococcus lactis cells and identification of genes affecting nisin production. The highest transformation efficiency, 1.1 x 10(2) transformants microg(-1) of input transposon DNA, was achieved when cells were grown to an OD(600) of 0.5 in the presence of 1.5% of glycine and treated with 20 microg ml(-1) ampicillin for 60 min. Three insertions affecting nisin production, which were identified at nisB, fhuR, and rpiA genes, were screened from a library of approximately 2000 erythromycin-resistant transformants using a nisin bioassay method. NisB is part of the nisin biosynthetic machinery, explaining the loss of nisin production in nisB mutant. FhuR is a transcription regulator involved in sulphur acquisition. Inactivation of fhuR presumably results in a low cellular cystein level, which affects nisin biosynthesis that involves utilization of cystein. RpiA is involved in pentose phosphate pathway and carbon fixation. The rpiA mutant showed reduction in nisin production and slow growth rate. The results showed that Mu transposition complex mutagenesis can be used to identify genes in L. lactis. Three genes involved in nisin production were identified. Expanding the Mu transposition-based mutagenesis to Lactococci adds a new tool for studies of industrially important bacteria.
    Journal of Applied Microbiology 01/2009; 106(1):41-8. DOI:10.1111/j.1365-2672.2008.03962.x · 2.39 Impact Factor
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    J H Wong · J Hao · Z Cao · M Qiao · H Xu · Y Bai · T B Ng
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    ABSTRACT: To isolate and characterize an antifungal protein from the culture broth of the bacterium Bacillus amyloliquefaciens. The antifungal protein designated as baciamin was isolated and exhibited a molecular mass around 50 kDa. Baciamin manifested a broad spectrum of antifungal activity. Baciamin could induce membrane permeabilization of tested fungi. Its antifungal activity was retained after incubation with trypsin and EDTA. Various ions tested did not affect its antifungal activity. Baciamin reduced the activity of HIV-1 reverse transcriptase (RT). It also inhibited proliferation of hepatoma, breast cancer and colon cancer cell lines. Baciamin augmented nitric oxide production by mouse macrophages. Bacillus amyloliquefaciens produces a broad-spectrum antifungal protein, baciamin. It induces membrane permeabilization in fungi but not in rabbit erythrocytes. Its antifungal activity is relatively thermostable, pH- and trypsin-stable. It demonstrates antiproliferative activity towards various tumour cells, nitric oxide-inducing activity towards macrophages, and inhibitory activity towards HIV-1 RT. Baciamin represents one of the few bacterial antifungal proteins reported to date. Most of the previously isolated antifungal molecules of bacterial origin are either peptides or ring compounds. Baciamin also exhibits other exploitable activities such as antitumour and immuno-enhancing activities.
    Journal of Applied Microbiology 01/2009; 105(6):1888-98. DOI:10.1111/j.1365-2672.2008.03917.x · 2.39 Impact Factor

Publication Stats

40 Citations
8.10 Total Impact Points

Institutions

  • 2009
    • Peking University Health Science Center
      Peping, Beijing, China
    • Nankai University
      • College of Life Sciences
      T’ien-ching-shih, Tianjin Shi, China