Recently, RNA-guided genome editing using the type II clustered regularly interspaced short palindromic repeats (CRISPR)-associated protein (Cas) system has been applied to edit the plant genome in several herbaceous plant species. However, it remains unknown whether this system can be used for genome editing in woody plants. In this study, we describe the genome editing and targeted gene mutation in a woody species, Populus tomentosa Carr. via the CRISPR/Cas9 system. Four guide RNAs (gRNAs) were designed to target with distinct poplar genomic sites of the phytoene desaturase gene 8 (PtoPDS) which are followed by the protospacer-adjacent motif (PAM). After Agrobacterium-mediated transformation, obvious albino phenotype was observed in transgenic poplar plants. By analyzing the RNA-guided genome-editing events, 30 out of 59 PCR clones were homozygous mutants, 2 out of 59 were heterozygous mutants and the mutation efficiency at these target sites was estimated to be 51.7%. Our data demonstrate that the Cas9/sgRNA system can be exploited to precisely edit genomic sequence and effectively create knockout mutations in woody plants.

Carbon-based materials are considered to be active for electrochemical oxygen reduction reaction (ORR) to hydrogen peroxide (H2O2) production. Nevertheless, less attention is paid to the investigation of the influence of in-plane carbon lattice defect on the catalytic activity and selectivity toward ORR. In the present work, graphene precursors were prepared from oxo-functionalized graphene (oxo-G) and graphene oxide (GO) with H2O2 hydrothermal treatment, respectively. Statistical Raman spectroscopy (SRS) analysis demonstrated the increased in-plane carbon lattice defect density in the order of oxo-G, oxo-G/H2O2, GO, GO/H2O2. Furthermore, nitrogen-doped graphene materials were prepared through ammonium hydroxide hydrothermal treatment of those graphene precursors. Rotating ring-disk electrode (RRDE) results indicate that the nitrogen-doped graphene derived from oxo-G with lowest in-plane carbon lattice defects exhibited the highest H2O2 selectivity of >82% in 0.1 M KOH. Moreover, a high H2O2 production rate of 224.8 mmol gcatalyst –1 h–1 could be achieved at 0.2 VRHE in H-cell with faradaic efficiency of >43.6%. Our work provides insights for the design and synthesis of carbon-based electrocatalysts for H2O2 production.

Inorganic carbonates are often used to establish radiocarbon (14 C) chronologies for lake sediments when terrestrial plant remains (TPR) are rare or when bulk organic matter is insufficient for dating, a problem that is common for many lakes in arid regions. However, the reservoir effect (RE), as well as old carbon contributed from the lakes catchment make it difficult to establish reliable chronologies. Here we present a systematic study of inorganic 14 C ages of two lake-sediment sequences, one from a small-enclosed saline lake-Lake Gahai in Qaidam Basin, and the other from a large freshwater lake-Lake Bosten in Xinjiang. Modern dissolved inorganic carbon (DIC) of the lakes, paleo-lake sediments exposed in the catchment, and mollusk shells in core sediments from Lake Gahai were dated to assess the RE and the contribution of pre-aged carbon to the old ages in the cores. We propose a statistical regression to assess more than one RE for the 14 C carbonate ages within our sedimentary sequences. Old radiocarbon ages contributed by detrital carbonates were assessed by comparing the ages of mollusk shells with those of carbonates at the same sediment depths. We established the RE of the authigenic component and assessed detrital old carbon contributions to our two sites, and this was used to correct the 14 C ages. Based on this approach, we developed age models for both cores, and tested them using 210 Pb ages in both cores and TPR-based 14 Cages recovered from Lake Bosten. We further tested our age models by comparing carbonate-based oxygen isotope (δ 18 O) records from both lakes to an independently-dated regional speleothem δ 18 O record. Our results suggest if sedimentary sequences are densely dated and the RE and the contribution of old carbon from detrital carbonates can be ascertained, robust chronological frameworks based on carbonate-based 14 C determinations can be established.

No abstract

This study involves elucidation of spatial and temporal influences on horizontal and vertical distribution and fate of contaminants of emerging concerns (CECs) in riverain systems. In total, 23 CECs encompassing antibiotics, nonantibiotic drugs, and bisphenol analogues were detected. The antibiotic concentrations were relatively higher in deep water than in surface water. Spatial connectivity and spatial autocorrelation suggested the occurrence and concentration of the majority of the CECs devoid of neighboring site influences, owing to shorter correlation lengths than the average distances between the sampling sites, hence indicating the localized distribution of CECs in surface water. The PCA biplot indicated that bisphenol A and methyl paraben were mainly responsible for the seasonal variations. Both negative and positive correlations existed between CECs and the environmental parameters to cause temporal variations in CEC contaminants. Spatial structure analysis by singular vector decomposition (SVD) analysis was used to measure the sitewise contribution of CECs. The results indicated relatively higher CEC contaminants and deteriorated water quality in the downstream sites rather than in the upstream sites. This study effectively demonstrated the use of different chemometric techniques for in-depth understanding of various spatial and temporal influences on the fate and horizontal and depth distribution of CECs in riverain systems.