Guangxi University

The determination of total arsenic across diverse environmental matrices remains a significant challenge. To address the spatial and temporal delays and interference from complex field matrices inherent in traditional laboratory analysis methods, this study developed a continuous, automated, and long-term monitoring system for total dissolved inorganic arsenic (TDIAs). The system enables on-line real-time monitoring of TDIAs in natural waters. Through optimizing the instrumental parameters and chemical vapor generation conditions, the reaction kinetic process of As(Ⅴ) pre-reduction process was thoroughly investigated. In addition, a workflow for the on-site determination of TDIAs in natural waters was designed, including on-line filtration, sample acidification, pre-reduction, analytical detection and single-point calibration. The results demonstrated that the limit of detection (LOD) reached as low as 0.005 μg/L, with a linear range of 0.0-5.0 μg/L under the optimal parameter conditions, and the relative standard deviations (RSDs) were in the range of 0.6 %-7.3 %, which demonstrated a good analytical precision. The method validation showed that the recoveries of different matrix samples, such as tap water, lake water and seawater, were stable in the range of 97.8 %-107.8 %, which proved that the method has excellent ability of resisting matrix interference. Finally, the method has been successfully applied to the on-site determination of TDIAs in the Jinjiang River Estuary, Quanzhou Bay.

Mesoporous SBA-15 silica was used as the carrier of 1,8-naphthalimide fluorophore and layered double hydroxides (LDHs), to construct a bifunctional composite material (LDH@NA-SBA) for the adsorption and sensing of tetracycline antibiotics (TCs). LDHs dispersed on SBA-15 overcame the shortcomings of easy agglomeration and improved the adsorption capacity. The adsorption of TCs on LDH@NA-SBA occurred due to electrostatic interaction, π-π stacking, hydrogen bonding and complexation. In addition, after dispersing LDHs on NA-SBA-15, the fluorescence changed from blue to cyan, which realized colorimetric detection capability. And the pre-concentration promoted the photoinduced electron transfer (PET), which improved the detection sensitivity. The limit of detection (nM) for TC, OTC and CTC were 4.9, 2.0, and 2.2, respectively, which were significantly lower than those of NA-SBA-15. TCs detection by LDH@NA-SBA was attributed to the PET mechanism. Moreover, LDH@NA-SBA with a good regeneration capability can obtain satisfactory recovery rate for the detection of TC in real samples.

Litchi downy blight caused by Peronophythora litchii is the most destructive disease of litchi (Litchi chinensis). RACK1 (Receptor for activated C kinase 1) is a group of scaffold proteins, mainly involved in the regulation of various signaling pathways by interacting with signal transduction proteins and affecting the activity of these proteins. In this study, a RACK1 homologue identified in P. litchii, and named PlRACK1. The protein was found to interact with the mitogen-activated protein kinases, PlMAPK1 and PlMAPK2. CRISPR/Cas9-mediated genome editing technology was used to knock out PlRACK1, and we found that it was involved in mycelial growth, cell wall integrity, ROS metabolism, laccase activity, and pathogenicity of P. litchii. PlMAPK1 interacted with RACK1, and they jointly regulated sporangiophore branching of P. litchii. Transcriptome analysis showed that P. litchii MAPK Phosphatase 1 (PlMKP1) and beta-glucoside (PlBglX) were regulated by PlRACK1, both of which were also required for the pathogenicity of P. litchii. As well, PlMKP1 also interacted with PlMAPK1 and PlMAPK2. These results provide insights into the direct interactions between RACK1, MAPKs, and MKP, and their functions in growth, development, and pathogenesis in a plant pathogenic oomycete.