Polychlorinated biphenyls (PCBs) are considered as persistent organic pollutants. Their long term accumulation in soils and progressive bioaccumulation in the food chain makes PCBs a risk for human health. Phytoremediation, or the use of plants to enhance pollutant dissipation, is an efficient technique for the removal of organic compounds, including PCBs. However, the molecular basis of plant responses to PCBs has not been clearly elucidated. Here we studied the effects on growth and the transcriptional profile of Arabidopsis thaliana after exposure to 2,2 0 ,3,3 0 -tetrachlorobiphenyl, a representative PCB. A comprehensive survey of global gene expression response to this PCB was done by using Arabidopsis (V4) gene expression microarray (4 9 44 K) to quantify the spatio-temporal variations in transcript abundance of 42,000 genes. The results revealed a coordinated induction or suppression of 146 or 148 genes, respectively. Of these, expression of 40 genes was validated by RT-PCR analysis.The functional classification of these PCB-responsive genes indicated their involvement in various metabolic pathways, such as ion transport, signal transduction, transcriptional regulation, and other processes related to growth and development.
As one of China's great metropolises, Shanghai is vulnerable to various forms of industrial and agricultural contamination associated with its development. Polychlorinated biphenyls (PCBs) are man-made chemicals that never existed in nature until the 1900s when they started to be released into the environment. PCBs are hazardous environmental contaminants that bind strongly to soil. In this study, four soil samples were screened for the presence of PCB-degrading bacteria. The 16 S rDNAs were amplified from those genomes and the products (~1.5 kb) were purified and sequenced for the isolation and identification of bacterial species. Four Pseudomonas strains (strain 1-212 from sample 1; strain 2-241 from sample 2; strain 3-318 from sample 3; and strain 4-150 from sample 4) were selected for analysis by HPLC. Setting the content of the biphenyl in CK as 100%, the biphenyl contents was 2.32% in 1-212, 73.11% in 2-241, 69.83% in 3-318, and 86.16% in 4-150. The results of this study suggest directions for future research, including genetic screening, cloning and restructuring, and provide guidance for the cultivation of PCBs-degrading bacteria.
A 2,3-dihydroxybiphenyl (2,3-DHBP) dioxygenase gene from a Rhodococcus sp. strain, named RrbphCI and involved in the degradation of polychlorinated biphenyls (PCBs), was synthesized. RrbphCI was expressed in Escherichia coli and its encoded enzyme was purified. SDS-PAGE analysis indicated that the size of the protein encoded by RrbphCI was about 32 kDa. The activity of the 2,3-DHBP dioxygenase was 82.8 U/mg when the substrate was 2,3-DHBP, with optimum pH 8.0 at 30°C, and optimum temperature was 40°C at pH 8.0. The RrbphCI gene was transformed into Pseudomonas putida strain EG11, to determine the ability of the enzyme to degrade 2,3-DHBP. The wild type EG11 degraded 61.86% of supplied 2,3-DHBP and the transformed EG11 (hosting the RrbphCI gene) utilized 52.68% after 2 min of treatment at 30°C. The overexpressed and purified enzyme was able to degrade 2,3-DHBP. The 2,3-DHBP dioxygenase is a key enzyme in the PCB degradation pathway. RrbphCI and its encoded 2,3-DHBP dioxygenase may have transgenic applications in bioremediation of PCBs.
Polychlorinated biphenyls (PCBs), the chlorinated derivatives of biphenyl, are one of the most prevalent, highly toxic and persistent groups of contaminants in the environment. The objective of this study was to investigate the biodegradation of PCBs in northeastern (Heilongjiang Province), northern (Shanxi Province) and eastern China (Shanghai municipality). From these areas, nine soil samples were screened for PCB-degrading bacteria using a functional complementarity method. The genomic 16S rDNA locus was amplified and the products were sequenced to identify the bacterial genera. Seven Pseudomonas strains were selected to compare the capacity of bacteria from different regions to degrade biphenyl by HPLC. Compared to the biphenyl content in controls of 100%, the biphenyl content went down to 3.7% for strain P9-324, 36.3% for P2-11, and 20.0% for the other five strains. These results indicate that a longer processing time led to more degradation of biphenyl. PCB-degrading bacterial strains are distributed differently in different regions of China.
As one of the persistent organic pollutants, polychlorinated biphenyls are harmful to the environment and humans. Biodegradation is the most potential way to remove PCBs. Biodegradation can mainly be divided into microbial degradation, phytoremediation, plant and microbial combined remediation. Here, we introduced isolation of the PCBs-degrading strains, cloning and modification of the related degradation genes. Additionally, on the other hand, the natural remediation of plant, plant and microbial combined remediation, plant transgenic remediation were described.
Background:
Previous clinical studies have reported that full field digital mammography (FFDM) can be used for diagnosis on breast cancer (BC) with promising outcome results. However, no study systematically investigates its diagnostic impact on female patients with BC. Thus, this systematic review will assess the accurate of FFDM diagnosis on BC.
Methods:
In this study, we will perform a comprehensive search strategy in the databases as follows: Cochrane Library, EMBASE, MEDILINE, PSYCINFO, Web of Science, Cumulative Index to Nursing and Allied Health Literature, Allied and Complementary Medicine Database, Chinese Biomedical Literature Database, China National Knowledge Infrastructure, VIP Information, and Wanfang Data from inception to February 28, 2019. All case-controlled studies exploring the impacts of FFDM diagnosis for patients BC will be fully considered for inclusion in this study. Two authors will independently scan the title and abstracts for relevance, and assess full texts for inclusion. They will also independently extract data and will assess methodological qualify for each included study by using Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. RevMan V.5.3 software (London, UK) and Stata V.12.0 software (Texas, USA) will be used to pool the data and to conduct the meta-analysis.
Results:
The sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio of FFDM will be used to determine the diagnostic accuracy of FFDM for the diagnosis of patients with BC.
Conclusion:
Its findings will provide latest evidence for the diagnostic accuracy of FFDM in female patients with BC.
Systematic review registration:
PROSPERO CRD42019125338.
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