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[en] Cr(VI) is a well known environmental carcinogen, but its mechanism of action and the measures required to mitigate its effects remain to be investigated. Our previous studies showed that exposure of human bronchial epithelial (BEAS-2B) cells to Cr(VI) caused malignant transformation, that these transformed cells progressed through tumorigenesis, and that luteolin, a natural compound, inhibited both of these processes. The present study investigates the underlying mechanisms by which luteolin protects cells against Cr(VI)-induced transformation and tumorigenesis. The present study shows that luteolin activates inducible Nrf2 to inhibit Cr(VI)-generated reactive oxygen species (ROS) in normal BEAS-2B cells. The decreased ROS level is likely responsible for the protective effect of luteolin against Cr(VI)-induced malignant cell transformation in normal cells. By contrast, in cells that have been transformed by Cr(VI), Nrf2 is constitutively activated, and its target proteins, heme oxygenase 1 (HO-1), NAD(P)H:quinone oxidoreductase 1 (NQO1), and superoxide dismutase 1/2 (SOD1/SOD2) are all constitutively activated, and ROS levels are low. Bcl-2, an anti-apoptotic protein and target protein of Nrf2 is elevated. Cr(VI)-transformed BEAS-2B cells develop apoptosis resistance, increasing the survival of these transformed cells. Luteolin decreases interactions between Nrf2 and the antioxidant response element sites of its target anti-apoptotic and antioxidant proteins, Bcl-2, Bcl-XL, and HO-1, which results in decreased constitutive Nrf2 activation. The decreased constitutive Nrf2 activation, decrease in Nrf2 target proteins and consequent apoptosis resistance by luteolin are possible mechanisms that mediate the protective effect of luteolin in Cr(VI)-transformed cells. - Highlights: • Constitutive Nrf2 activation in Cr(VI)-transformed cells is oncogenic. • Constitutive Nrf2 activation decreases ROS with development of apoptosis resistance. • Luteolin inhibits constitutive Nrf2 activation in Cr(VI)-transformed cell. • Dietary strategies using luteolin may prevent Cr(VI)-induced carcinogenesis.
[en] This paper studied the inhibitory effect of pomegranate peel (PP) extract on the growth of Microcystis aeruginosa, the model of harmful algal blooms in aquatic environment. The allelochemicals were identified by HPLC–MS/MS from PP and tested by batch experiment through measurement of algal density, chlorophyll a (Chl-a) concentration, maximum quantum yield of photosystem II (Fv/Fm), superoxide dismutase (SOD), and malondialdehyde (MDA) contents. Results showed that both PP powder and PP extract had obvious inhibitory effect on M. aeruginosa growth. Quercetin and luteolin were identified as the allelochemicals to M. aeruginosa growth. However, the inhibitory capacity of luteolin was stronger than that of quercetin. The growth inhibition ratio of luteolin can reach up to 98.7 and 99.1% of the control on day 7 at the dosages of 7 and 10 mg/L, respectively. Moreover, the changes of Chl-a, Fv/Fm, SOD, and MDA in M. aeruginosa confirmed jointly that the allelochemicals cause inhibition of photosystem and oxidative damage to M. aeruginosa cells with the antioxidant defense system being activated, which leads to the aggravation of membrane lipid peroxidation. Thus, luteolin could be used as a promising algaecide for emergency handling of M. aeruginosa blooms. This study might provide a new direction in the management of eutrophication in the future.
[en] Sustainable and cost effective food preservation techniques are of industrial, environmental and public health significance globally. A promising means for the gentle but efficient sanitation of foods is the application of cold atmospheric plasma. Here, the preservation of fresh-cut apples was investigated using a gas phase surface discharge plasma (SDP) reactor within an exposure chamber. Results show that the microbial load reduction of the fresh-cut apples was found to be strongly dependent on the storage time and preservation method, e.g. refrigeration (control), SDP-room temperature and SDP-refrigeration (SDP-RF). After 6 d of storage, the microbe load on the apple pieces for the SDF-RF treated groups was found to be significantly lower compared to the refrigeration-stored (4 °C) and the SDP only-processed groups, with the lowest bacterial load on the 120 s SDP-RF stored apple pieces (1.76 CFU g−1). Furthermore, the effects of the preservation method on the quality attributes (weight loss, firmness, and physical appearance), and the surface chemistry directly after cutting and SDP processing, as well as the activities of polyphenol oxidase and peroxidase after the different duration of storage were evaluated. This study successfully demonstrates the feasibility of SDP for the effective preservation of fresh-cut apples and contributes to the fundamental understanding of surface plasma-induced effects on the microbial inactivation and postharvest quality of fresh-cut fruits. (paper)
[en] Abrasive Water Jet Machining (AWJM) is well known non-traditional machining process employed to machine difficult to cut materials with complex contours. The proposed research work deals with the machinability investigation of AA-2024-B4C-TiC hybrid composite through AWJM process. The machining characteristics as output responses for the analysis are Surface Roughness (SR), Material Removal Rate (MRR) and Kerf angle (KA). The effect of individual process parameters are water Jet Pressure (JP), Standoff Distance (SOD) and Traverse Speed (TS), these parameters holds higher degree of influence over output responses. The influence analysis shows the notable increment in the metal removal process with the increased SOD, TS and water pressure. Moreover, the optimal combination of process parameters and their contribution are determined through Grey Relational Analysis (GRA). The optimum parameters obtained from GRA are water jet pressure of 260 bar, stand-off distance at 1 mm and traverse speed of 20 mm min−1. Moreover, the most significant factor on affecting the responses were water jet pressure (82.17%) followed by the transverse speed (13.84%) (paper)
[en] Dipeptidylpeptidase IV (DPP-IV) is a well-documented drug target for the treatment of type 2 diabetes. Hepatocyte nuclear factors (HNF)-1α and HNF-1β, known as the causal genes of MODY3 and MODY5, respectively, have been reported to be involved in regulation of DPP-IV gene expression. But, it is not completely clear (i) that they play roles in regulation of DPP-IV gene expression, and (ii) whether DPP-IV gene activity is changed by mutant HNF-1α and mutant HNF-1β in MODY3 and MODY5. To explore these questions, we investigated transactivation effects of wild HNF-1α and 13 mutant HNF-1α, as well as wild HNF-1β and 2 mutant HNF-1β, on DPP-IV promoter luciferase gene in Caco-2 cells by means of a transient experiment. Both wild HNF-1α and wild HNF-1β significantly transactivated DPP-IV promoter, but mutant HNF-1α and mutant HNF-1β exhibited low transactivation activity. Moreover, to study whether mutant HNF-1α and mutant HNF-1β change endogenous DPP-IV enzyme activity, we produced four stable cell lines from Caco-2 cells, in which wild HNF-1α or wild HNF-1β, or else respective dominant-negative mutant HNF-1αT539fsdelC or dominant-negative mutant HNF-1βR177X, was stably expressed. We found that DPP-IV gene expression and enzyme activity were significantly increased in wild HNF-1α cells and wild HNF-1β cells, whereas they decreased in HNF-1αT539fsdelC cells and HNF-1βR177X cells, compared with DPP-IV gene expression and enzyme activity in Caco-2 cells. These results suggest that both wild HNF-1α and wild HNF-1β have a stimulatory effect on DPP-IV gene expression, but that mutant HNF-1α and mutant HNF-1β attenuate the stimulatory effect
[en] The report briefly describes work carried out on the following subjects: Determination of protein in fungal strains (including Fusarium and Aspergillus niger); induction and selection of mutants (Aspergillus niger) giving higher yields of biomass and/or higher protein content; ability of fungi (Candida tropicalis) to utilize water extracts of carob bean pods; growth of Fusarium monoliforme at the expense of carob sugars; the use of alternate oxidase-negative mutants (of Ustilago maydis), for better utilization of substrates for growth (electron transport pathways in reoxidation of reduced coenzymes); kinetics of batch and continuous cultivation of Fusarium moniliforme (cultivated on aqueous carob extracts)
[en] Expression of Bacterial luciferase enzyme (lux) in mammalian cells would be a powerful bioreporter protein system for in vivo imaging because eukaryotic luciferases need expensive substrates. However, only a few efforts have been made to express bacterial luciferase enzyme in mammalian cells. As the result of this, we attempted to construct bicistronic vector including two bacterial luciferase genes (LuxA and LuxB) for assessing the potential to be visualized in vitro or in vivo by optical imaging system after transfection to mammalian cells. We designed and synthesized luxA and luxB genes from Photorhabdus Luminescens. To co-express both luxA and luxB genes from a single promoter, we cloned as a bicistronic transcript fused with an internal ribosomal entry site (IRES). This bicistronic transcript was transfected by Superfect to HEK 293T cell line. We also transfected lux A and lux B vector to HEK 293T cells separately. To evaluate gene expression, n-decanal and FMNH2 were supplemented to transfected HEK 293T cell lines which were measured by In Vivo Imaging System. The luxA gene was cloned into the MCS(A) of pIRESGFP via the 5' SalI and 3' EcoRI restriction sites to generate pIRESluxA. The luxB gene was cleaved via a 5' NcoI and 3' NotI site from luxB and cloned into the MCS(B) of pIRESluxA to generate pIRESluxAB. LuxA and B genes was cleaved by 5' EcoRI and 3' SpeI and cloned into the pcDNA3.1 mammalian expression vector to create pcDNALuxA and pcDNALuxB. We constructed bicistronic vector system which is composed of bacterial luciferase genes (lux A and B) on the single reading frame. These results hold a promise of an available development of an autonomous light generating lux reporter system in mammalian cells