The Ecological Status and Change in High-Latitude Coral Assemblages at the Xuwen Coral Reef, Northern South China Sea: Insight into the Status and Causes in 2020.

Taking the coral communities of the Xuwen coral reef in 2020 as the research object, we analyzed the species composition, diversity, and interspecific Spearman correlation of the scleractinian coral communities, investigated the features and spatial distribution of the scleractinian coral community, and discussed the correlation between the community composition and environmental factors to identify the affecting factors and their sources. These results showed that (1) compared with the survey in 2004, the coverage of corals in 2020 had significantly decreased, while the dominant genera were still Goniopora and Porites. The coral morphology was massive, and the diversity of the coral community (Shannon-Wiener index, H') was 2.87. The distribution of coral was uneven. The competition among some dominant species of coral was intense. (2) The mass coral bleaching event in the NSCS in August 2020 did not cause severe coral death in the short term on the Xuwen coral reef. (3) The growth of the coral community in 2020 might be greatly affected by high suspended solids and nutrient levels, which were related to the current, mariculture, and coastal erosion. (4) Anthropogenic activities such as coastal aquaculture and fishing were the major factors leading to the reduction in coral coverage on Xuwen coral reef in the past 10 years.

High vulnerability and a big conservation gap: Mapping the vulnerability of coastal scleractinian corals in South China.

Scleractinian corals build the most complex and diverse ecosystems in the ocean with various ecosystem services, yet continue to be degraded by natural and anthropogenic stressors. Despite the rapid decline in scleractinian coral habitats in South China, they are among the least concerning in global coral vulnerability maps. This study developed a rapid assessment approach that combines vulnerability components and species distribution models to map coral vulnerability within a large region based on limited data. The approach contained three aspects including, exposure, habitat suitability, and coral-conservation-based adaptive capacity. The exposure assessment was based on seven indicators, and the habitat suitability was mapped using Maximum Entropy and Random Forest models. Vulnerability of scleractinian corals in South China was spatially evaluated using the approach developed here. The results showed that the average exposure of the study region was 0.62, indicating relatively high pressure. The highest exposure occurred from the east coast of the Leizhou Peninsula to the Pearl River Estuary. Aquaculture and shipping were the most common causes of exposure. Highly suitable habitats for scleractinian corals are concentrated between 18°N-22°N. Only 21.6 % of the potential coral habitats are included in marine protected areas, indicating that there may still be large conservation gaps for scleractinian corals in China. In total, 37.7 % of the potential coral habitats were highly vulnerable, with the highest vulnerability appearing in the Guangdong Province. This study presents the first attempt to map the vulnerability of scleractinian corals along the coast of South China. The proposed approach and findings provide an essential tool and information supporting the sustainable management and conservation of coral reef ecosystems, addressing an important gap on the world's coral reef vulnerability map.

Polypyrrole Decorated Flower-like and Rod-like ZnO Composites with Improved Microwave Absorption Performance.

In this study, zinc oxide (ZnO)/polypyrrole (PPy) composites with flower- and rod-like structures were successfully fabricated by in situ polymerization and the hydrothermal method and used as microwave absorption (MWA) materials. The surface morphologies, crystal structures, and electromagnetic features of the as-prepared samples were measured by field-emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and vector network analyzer (VNA). The results show that the conductive polymer PPy was successfully decorated on the surface of ZnO substrates. The MWA ability of flower- and rod-like ZnO/PPy composites is significantly enhanced after introduction of PPy. Rod-like ZnO/PPy composites exhibited superior MWA properties than those of flower-like ZnO/PPy. The former achieved a minimum reflection loss (RLmin) of −59.7 dB at 15.8 GHz with a thickness of 2.7 mm, and the effective absorption bandwidth (EAB, RL < −10 dB) covered 6.4 GHz. PPy addition and stacked structure of rod-like ZnO/PPy composites can effectively improve the dielectric properties, form multiple reflections of incident electromagnetic waves, and generate an interfacial polarization effect, resulting in improved MWA properties of composite materials.

Gain-of-Function Mutations in Acid Stress Response (evgS) Protect Escherichia coli from Killing by Gallium Nitrate, an Antimicrobial Candidate.

Widespread antimicrobial resistance encourages repurposing/refining of nonantimicrobial drugs for antimicrobial indications. Gallium nitrate (GaNt), an FDA-approved medication for cancer-related hypercalcemia, recently showed good activity against several clinically significant bacteria. However, the mechanism of GaNt antibacterial action is still poorly understood. In the present work, resistant and tolerant mutants of Escherichia coli were sought via multiple rounds of killing by GaNt. Multiround-enrichment yielded no resistant mutant; whole-genome sequencing of one representative GaNt-tolerant mutant uncovered mutations in three genes (evgS, arpA, and kdpD) potentially linked to protection from GaNt-mediated killing. Subsequent genetic analysis ruled out a role for arpA and kdpD, but two gain-of-function mutations in evgS conferred tolerance. The evgS mutation-mediated GaNt tolerance depended on EvgS-to-EvgA phosphotransfer; EvgA-mediated upregulation of GadE. YdeO, and SarfA also contributed to tolerance, the latter two likely through their regulation of GadE. GaNt-mediated killing of wild-type cells correlated with increased intracellular reactive oxygen species (ROS) accumulation that was abolished by the evgS-tolerant mutation. Moreover, GaNt-mediated killing was mitigated by dimethyl sulfoxide, and the evgS-tolerant mutation upregulated genes encoding enzymes involved in ROS detoxification and in the glyoxylate shunt of the tricarboxylic acid (TCA) cycle. Collectively, these findings indicate that GaNt kills bacteria through elevation of ROS; gain-of-function mutations in evgS confer tolerance by constitutively activating the EvgA-YdeO/GadE cascade of acid resistance pathways and by preventing GaNt-stimulated ROS accumulation by upregulating ROS detoxification and shifting TCA cycle carbon flux. The striking lethal activity of GaNt suggests that clinical use of the agent may not quickly lead to resistance.

[Application of "omics" in bioremediation--a review].

Environmental pollutants are a major concern worldwide. Bioremediation mediated by microorganisms is a highly promising technology that is environmentally friendly, safe and effective. However, successful execution of these bioremediation strategies requires a complete understanding of factors governing the growth, metabolism, dynamics and functions of indigenous microbial communities at contaminated sites. The combination of genomics, transcriptomics, proteomics and metabolomics has provided a crucial insight into microbial communities and their mechanisms in bioremediation of polluted environment. This current review is focused on application of these technologies in bioremediation at contaminated sites. Limitations of each "-omics" analysis are briefly discussed and integration of these "-omics" technologies in study the processes of harmful algal bloom and the microbial degradation metabolism of organic pollutants are presented.