Toxicity evaluation of textile dyeing effluent and its possible relationship with chemical oxygen demand
ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY
Authors: Liang, Jieying; Ning, Xun-an; Sun, Jian; Song, Jian; Lu, Jie; Cai, Haili; Hong, Yanxiang
Abstract
Textile dyeing wastewater was the focus of much research because of its adverse effect on aquatic biota. In the present research, textile dyeing influent and effluent samples were collected from four textile dyeing wastewater treatment plants (TDPs) in Guangdong province, China, and their conventional indicators and toxicity were examined to reveal relationships. The relationship between toxicity and chemical oxygen demand (COD) was clearly established at individual TDPs. Results indicated the highest removal efficiencies of 94.4%, 90.6%, 91.9%, 94.6%, 92.8% and 97.5% for TOC, mixed-liquor volatile suspended solids (MLVSS), COD, ammonia nitrogen (NH3-N), total phosphorus (TP) and colour, respectively. The primary clarifier used in TDP3 and TDP4 was beneficial for removing macromolecular organic substances, and membrane filtration and sedimentation basin employed at TDP1 and TDP2, respectively, helped to remove toxic substances. Toxicity to V. fischeri or D. subspicatus was found to be related to certain conventional indicators such as TOC, COD, TP, colour, and MLVSS, and was positively correlated with COD in different textile dyeing effluents (R-2 > 0.84). It was recommended that the relationship between toxicity and COD in wastewater should be established individually at each plant. Therefore, this study could be useful in providing suggestions for guiding effluent management when no toxicity experiments were conducted.
Real-time detection of TDP1 activity using a fluorophore-quencher coupled DNA-biosensor
BIOSENSORS & BIOELECTRONICS
Authors: Jensen, Pia W.; Falconi, Mattia; Kristoffersen, Emil L.; Simonsen, Anita T.; Cifuentes, Jessica B.; Marcussen, Laerke B.; Frohlich, Rikke; Vagner, Josephine; Harmsen, Charlotte; Juul, Sissel; Ho, Yi-Ping; Withers, Marjorie A.; Lupski, James R.; Koch, Jorn; Desideri, Alessandro; Knudsen, Birgitta R.; Stougaard, Magnus
Abstract
Real-time detection of enzyme activities may present the easiest and most reliable way of obtaining quantitative analyses in biological samples. We present a new DNA-biosensor capable of detecting the activity of the potential anticancer drug target tyrosyl-DNA phosphodiesterase 1 (TDP1) in a very simple, high throughput, and real-time format. The biosensor is specific for Tdp1 even in complex biological samples, such as human cell extracts, and may consequently find future use in fundamental studies as well as a cancer predictive tool allowing fast analyses of diagnostic cell samples such as biopsies. TDP1 removes covalent 3'DNA adducts in DNA single-strand break repair. This enzymatic activity forms the basis of the design of the TDP1-biosensor, which consists of a short hairpin-forming oligonucleotide having a 5'fluorophore and a 3'quencher brought in close proximity by the secondary structure of the biosensor. The specific action of TDP1 removes the quencher, thereby enabling optical detection of the fluorophore. Since the enzymatic action of TDP1 is the only "signal amplification" the increase in fluorescence may easily be followed in real-time and allows quantitative analyses of TDP1 activity in pure enzyme fractions as well as in crude cell extracts. In the present study we demonstrate the specificity of the biosensor, its ability to quantitatively detect up- or down-regulated TDP1 activity, and that it may be used for measuring and for analyzing the mechanism of TDP1 inhibition. (C) 2013 Elsevier B.V. All rights reserved.