Microwave-assisted iron oxide process for efficient removal of tetracycline.

Excess tetracycline produced by livestock and poultry breeding industry not only pollute the environment, but also enter the human body with the spread of the food chain, which will produce drug-resistant genes and threaten human health. In this paper, the adsoption of tetracycline from wastewater using iron oxide under microwave oxidation condition was explored. The effect of initial pollutant concentrations, the dosage of iron oxide, pH value, and temperature on the hybrid treatment process was investigated. Under the normal iron oxide and microwave oxidation conditions, when the dosage of iron oxide was 40 g/L and 30 g/L, pH was 10 and the temperature was 318 K, the removal rate of tetracycline was significantly improved. The adsorption of tetracycline by iron oxide under the two conditions conformed to the Freundlich isotherm model and pseudo-second-order dynamics model. In addition, the associated adsorption mechanism was unveiled. Under the microwave oxidation condition, the hot spot effect generated by the microwave oxidation effect would rapidly increase its surface temperature to form the active center and the electrostatic gravity to promote the reaction. The results indicated that microwave oxidation could promote the removal of antibiotics by iron oxide in livestock and poultry breeding wastewater.

Impact assessment on the economy, society, resource, and environment in the water-receiving cities of the Middle Route Project of South-to-North Water Diversion.

The Middle Route Project of South-to-North Water Diversion (MRPSNWD) is a major strategic project to alleviate the serious shortage of water resources in northern China, and it benefited 14 large- and medium-sized cities in Henan, Hebei, Beijing, and Tianjin. Most of the predecessors used qualitative analysis to study the impact of the MRPSNWD on the water-receiving cities (WRCs), and they only considered one aspect of economy, society, resources, and environment, which could not fully reflect the impact of the MRPSNWD on the water-receiving cities. Therefore, based on the data of economic and social resources and environment of the water-receiving cities in the MRPSNWD from 2010 to 2019, an evaluation model based on entropy weight-analytic hierarchy process (AHP) fuzzy comprehensive evaluation method was constructed to account for the impacts on the economy-society-resources-environment of the water-receiving cities after the operation of the MRPSNWD and scientifically evaluated the comprehensive benefits of the MRPSNWD. The evaluation results revealed that the economic and environmental impacts of the MRPSNWD on the water-receiving cities were more obvious than those on society and resources. As far as water-receiving cities were concerned, the impact of the Middle Route Project of South-to-North Water Diversion on Zhengzhou, Shijiazhuang, Tianjin, and Beijing was generally higher than that of other cities. As far as the Middle Route Project of South-to-North Water Diversion was concerned, its overall impact on water-receiving cities was relatively slow.

Concurrent Disruption of Genetic Interference and Increase of Genetic Recombination Frequency in Hybrid Rice Using CRISPR/Cas9.

Manipulation of the distribution and frequency of meiotic recombination events to increase genetic diversity and disrupting genetic interference are long-standing goals in crop breeding. However, attenuation of genetic interference is usually accompanied by a reduction in recombination frequency and subsequent loss of plant fertility. In the present study, we generated null mutants of the ZEP1 gene, which encodes the central component of the meiotic synaptonemal complex (SC), in a hybrid rice using CRISPR/Cas9. The null mutants exhibited absolute male sterility but maintained nearly unaffected female fertility. By pollinating the zep1 null mutants with pollen from indica rice variety 93-11, we successfully conducted genetic analysis and found that genetic recombination frequency was greatly increased and genetic interference was completely eliminated in the absence of ZEP1. The findings provided direct evidence to support the controversial hypothesis that SC is involved in mediating interference. Additionally, the remained female fertility of the null mutants makes it possible to break linkage drag. Our study provides a potential approach to increase genetic diversity and fully eliminate genetic interference in rice breeding.

Erratum to: Rapid generation of genetic diversity by multiplex CRISPR/Cas9 genome editing in rice.

The same figure was misused for the PCR/RE assay results of Gn1a and GW2 fragments in Figure 3, and the arrows in the graphicsal result of GW2 were not on the tape. The corrected Figure 3 is as follows.

Clonal seeds from hybrid rice by simultaneous genome engineering of meiosis and fertilization genes.

Heterosis, or hybrid vigor, is exploited by breeders to produce elite high-yielding crop lines, but beneficial phenotypes are lost in subsequent generations owing to genetic segregation. Clonal propagation through seeds would enable self-propagation of F1 hybrids. Here we report a strategy to enable clonal reproduction of F1 rice hybrids through seeds. We fixed the heterozygosity of F1 hybrid rice by multiplex CRISPR-Cas9 genome editing of the REC8, PAIR1 and OSD1 meiotic genes to produce clonal diploid gametes and tetraploid seeds. Next, we demonstrated that editing the MATRILINEAL (MTL) gene (involved in fertilization) could induce formation of haploid seeds in hybrid rice. Finally, we combined fixation of heterozygosity and haploid induction by simultaneous editing of all four genes (REC8, PAIR1, OSD1 and MTL) in hybrid rice and obtained plants that could propagate clonally through seeds. Application of our method may enable self-propagation of a broad range of elite F1 hybrid crops.

A simple and efficient method for CRISPR/Cas9-induced mutant screening.

The clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) system provides a technological breakthrough in mutant generation. Several methods such as the polymerase chain reaction (PCR)/restriction enzyme (RE) assay, T7 endonuclease I (T7EI) assay, Surveyor nuclease assay, PAGE-based genotyping assay, and high-resolution melting (HRM) analysis-based assay have been developed for screening CRISPR/Cas9-induced mutants. However, these methods are time- and labour-intensive and may also be sequence-limited or require very expensive equipment. Here, we described a cost-effective and sensitive screening technique based on conventional PCR, annealing at critical temperature PCR (ACT-PCR), for identifying mutants. ACT-PCR requires only a single PCR step followed by agarose gel electrophoresis. We demonstrated that ACT-PCR accurately distinguished CRISPR/Cas9-induced mutants from wild type in both rice and zebrafish. Moreover, the method can be adapted for accurately determining mutation frequency in cultured cells. The simplicity of ACT-PCR makes it particularly suitable for rapid, large-scale screening of CRISPR/Cas9-induced mutants in both plants and animals.

Rapid generation of genetic diversity by multiplex CRISPR/Cas9 genome editing in rice.

The clustered regularly interspaced short palindromic repeats (CRISPR)-associated endonuclease 9 (CRISPR/Cas9) system has emerged as a promising technology for specific genome editing in many species. Here we constructed one vector targeting eight agronomic genes in rice using the CRISPR/Cas9 multiplex genome editing system. By subsequent genetic transformation and DNA sequencing, we found that the eight target genes have high mutation efficiencies in the T0 generation. Both heterozygous and homozygous mutations of all editing genes were obtained in T0 plants. In addition, homozygous sextuple, septuple, and octuple mutants were identified. As the abundant genotypes in T0 transgenic plants, various phenotypes related to the editing genes were observed. The findings demonstrate the potential of the CRISPR/Cas9 system for rapid introduction of genetic diversity during crop breeding.

Influence of Parent Artery Segmentation and Boundary Conditions on Hemodynamic Characteristics of Intracranial Aneurysms.

PURPOSE: The purpose of this study is to explore the influence of segmentation of the upstream and downstream parent artery and hemodynamic boundary conditions (BCs) on the evaluated hemodynamic factors for the computational fluid dynamics (CFD) analysis of intracranial aneurysms. MATERIALS AND METHODS: Three dimensional patient-specific aneurysm models were analyzed by applying various combinations of inlet and outlet BCs. Hemodynamic factors such as velocity pattern, streamline, wall shear stress, and oscillatory shear index at the systolic time were visualized and compared among the different cases. RESULTS: Hemodynamic factors were significantly affected by the inlet BCs while there was little influence of the outlet BCs. When the inlet length was relatively short, different inlet BCs showed different hemodynamic factors and the calculated hemodynamic factors were also dependent on the inlet length. However, when the inlet length (L) was long enough (L>20D, where D is the diameter of inlet section), the hemodynamic factors became similar regardless of the inlet BCs and lengths. The error due to different inlet BCs was negligible. The effect of the outlet length on the hemodynamic factors was similar to that of the inlet length. CONCLUSION: Simulated hemodynamic factors are highly sensitive to inlet BCs and upstream parent artery segmentation. The results of this work can provide an insight into how to build models and to apply BCs for more accurate estimation of hemodynamic factors from CFD simulations of intracranial aneurysms.