ABSTRACT
Acetic acid is a common inhibitor present in lignocellulosic hydrolysate. Development of acetic acid tolerant strains may improve the production of biofuels and bio-based chemicals using lignocellulosic biomass as raw materials. Current studies on stress tolerance of yeast Saccharomyces cerevisiae have mainly focused on transcription control, but the role of transfer RNA (tRNA) was rarely investigated. We found that some tRNA genes showed elevated transcription levels in a stress tolerant yeast strain. In this study, we further investigated the effects of overexpressing an arginine transfer RNA gene tR(ACG)D and a leucine transfer RNA gene tL(CAA)K on cell growth and ethanol production of S. cerevisiae BY4741 under acetic acid stress. The tL(CAA)K overexpression strain showed a better growth and a 29.41% higher ethanol productivity than that of the control strain. However, overexpression of tR(ACG)D showed negative influence on cell growth and ethanol production. Further studies revealed that the transcriptional levels of HAA1, MSN2, and MSN4, which encode transcription regulators related to stress tolerance, were up-regulated in tL(CAA)K overexpressed strain. This study provides an alternative strategy to develop robust yeast strains for cellulosic biorefinery, and also provides a basis for investigating how yeast stress tolerance is regulated by tRNA genes.
Subject(s)
Acetic Acid , DNA-Binding Proteins/metabolism , Fermentation , Leucine , RNA, Transfer/genetics , Saccharomyces cerevisiae/metabolism , Saccharomyces cerevisiae Proteins/metabolism , Transcription FactorsABSTRACT
Objective To study the correlation of cleft lip and palate transmembrane 1 like(CLPTM1L)expression and radiosensitivity of lung cancer cells.Methods Thiazolyl blue tetrazolium bromide(MTT) and cell colony formation assays were used to determine cell growth and survival.Western Blot assay was employed to measure protein expression.Results The results demonstrated a negative correlation between the CLPTM1L expression level and radiosensitivity of lung cancer cells.A lower radiosensitivity in lung cancer cells containing high level of CLPTM1L expression,and vice versa.Enforced expression of CLPTM1L resulted in a significant reduction of radiosensitivity in lung cancer cells irradiated with γ-rays.On the contrary,a marked elevation of radiosensitivity was observed in lung cancer cells transfected with CLPTM1L siRNA.Conclusions CLPTM1L may be a novel target gene in mediating radiosensitivity of lung cancer cells.
ABSTRACT
Objective To study the radioprotective effect of indole-3-carbinol (I3C) acid condensation products.Methods Cell colony formation assay was used to determine cell survival rate,and Western Blot assay was employed to measure protein expression.Results Seven kinds of the I3C acid condensation products showed different radioprotective effect on normal fibrous epithelial cells 184A1,among which 24 h pre-treatment of CTET (1 μmol/L),LTET (1 μmol/L),HI-IM (1 μmol/L) and 3,3'-diindoly methane (DIM) (0.3 μmol/L) showed significant increase of cell survival rate following irradiation with γ-ray,and the difficence was statistically significant (P＜0.05,P＜0.01).However,CT (1 μmol/L),LTr-1 (1 μmol/L) and ICZ (1 μmol/L) showed no effect on cell survival rate caused by radiation (P＞0.05).Furthermore,CTET,LTET,HI-IM and DIM activated the phosphorylation of ATM,BRCA1 and NBS1 proteins.HI-IM significantly decreased radiation-caused cell death and apoptosis.Conclusions CTET,LTET,HI-IM,and DIM can significantly reduce the radiosensitivity in 184A1 cells,and the mechanism may be related to the regulation of DNA damage and the repair of protein phosphorylation.
ABSTRACT
Qinghouliyan Chongji can markedly inhibit the swelling of ear induced by xylene in mice and the edema ofhind paw induced by egg white in rats. It can also decrease the weight of cotton pellet granuloma in rats.Numbers of writhing responses induced by acetic acid was reduced and pain threshold was elevated in mice bythis preparation,beside its bacteriostatic effects.
ABSTRACT
Intravenous injection of 13-n-Propyl-Palmatine 8 mg ? kg-1 reduced markedly the incidence of VF induced by chlorofom in the mice,elevated the threshold doses of Ouabain induced VP,VT,VF,CA in guinea pigs. Iv 1, 3mg ? kg-1 reduced signifi- cantly the incidence of arrhythmia induced by CaCl2 in the mice,shortened the total duration of arrhythmia induced by BaCl3 in therats. However, it was not so effective on A-conitine - induced arrhythmia in the rats. In addition, 13 - n - Propyl - Palmatine elevated significantly the activities of Na+, K+ - AT-Pase in the myocardial cellular membranes of rats.