prevention and management. Here we reported the screening, clinical feathers, and treatment process of a family cluster involving three COVID-19 patients. The discovery of the first asymptomatic carrier in this family cluster depends on the repeated and comprehensive epidemiological investigation by disease control experts. In addition, the combination of multiple detection methods can help clinicians find asymptomatic carriers as early as possible. In conclusion, the prevention and control experience of this family cluster showed that comprehensive rigorous epidemiological investigation and combination of multiple detection methods were of great value for the detection of hidden asymptomatic carriers.

Metabolomics is a rapidly emerging discipline within functional genomics which is increasingly being applied to 19 understand biochemical phenotypes across a range of biological systems. Metabolomics measures all (or a 20 subset) metabolites in a cell at a specific time point, reflecting a snapshot of all the regulatory events responding 21 to the external environmental conditions. Although metabolomics and system biology approaches have been ap-22 plied to the study of terrestrial plants, few marine macrophytes have been examined using these novel technol-23 ogies. Marine macrophytes (including seaweeds and seagrasses) are marine ecosystem engineers delivering a 24 range of ecologically and economically valuable biological services; however they are under threat from a wide 25 range of anthropogenic stressors, climate variation, invasive species and pathogens. Investigating metabolomic 26 regulation in these organisms is crucial to understand their acclimation, adaptation and defence responses to 27 environmental challenges. This review describes the current analytical tools available to study metabolomics 28 in marine macrophytes, along with their limitations for both targeted and non-targeted workflows. To illustrate 29 recent advances in system biology studies in marine macrophytes, we describe how metabolites are used in 30 chemical defence to deter a broad range of invasive species and pathogens, as well as metabolomic 31 reprogramming leading to acclimation or adaptive strategies to environmental and anthropogenic stresses. 32 Where possible, the mechanistic processes associated with primary and secondary plant metabolism governing 33 cellular homeostasis under extreme environments are discussed. Functional integration of metabolomics with 34 the allied "omics" disciplines of transcriptomics and proteomics, as well as the emerging discipline of "fluxomics" 35 are discussed in the context of developing biological system networks, the identification of unknown gene/pro-36 tein functions and the analysis of metabolic pathways in marine plants exposed to stress. Finally, we provide a 37 comprehensive overview of an in silico plant metabolome database that can be utilized to advance our knowl-38 edge from a system biology approach to marine macrophytes.

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Seagrasses are marine ecosystem engineers that are currently declining in abundance at an alarming rate due to both natural and anthropogenic disturbances in ecological niches. Despite reports on the morphological and physiological adaptations of seagrasses to extreme environments, little is known of the molecular mechanisms underlying photo-acclimation, and/or tolerance in these marine plants. This study applies the two-dimensional isoelectric focusing (2D-IEF) proteomics approach to identify photo-acclimation/tolerance proteins in the marine seagrass Zostera muelleri. For this, Z. muelleri was exposed for 10 days in laboratory mesocosms to saturating (control, 200 μmol photons m−2 s−1), super-saturating (SSL, 600 μmol photons m−2 s−1), and limited light (LL, 20 μmol photons m−2 s−1) irradiance conditions. Using LC-MS/MS analysis, 93 and 40 protein spots were differentially regulated under SSL and LL conditions, respectively, when compared to the control. In contrast to the LL condition, Z. muelleri robustly tolerated super-saturation light than control conditions, evidenced by their higher relative maximum electron transport rate and minimum saturating irradiance values. Proteomic analyses revealed up-regulation and/or appearances of proteins belonging to the Calvin-Benson and Krebs cycle, glycolysis, the glycine cleavage system of photorespiration, and the antioxidant system. These proteins, together with those from the inter-connected glutamate-proline-GABA pathway, shaped Z. muelleri photosynthesis and growth under SSL conditions. In contrast, the LL condition negatively impacted the metabolic activities of Z. muelleri by down-regulating key metabolic enzymes for photosynthesis and the metabolism of carbohydrates and amino acids, which is consistent with the observation with lower photosynthetic performance under LL condition. This study provides novel insights into the underlying molecular photo-acclimation mechanisms in Z. muelleri, in addition to identifying protein-based biomarkers that could be used as early indicators to detect acute/chronic light stress in seagrasses to monitor seagrass health.

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Rhizosphere bacterial community structures and their determining drivers have been studied in a variety of marine and freshwater ecosystems for a range of plant species. However, there is still limited information about the influence of habitat on microbial communities in seagrass beds. This study aimed to determine which factors (habitat and plant species) have crucial roles on the rhizospheric bacteria associated with two tropical seagrass species (Thalassia hemprichii and Enhalus acoroides) that are dominant at Xincun Bay and Tanmen Harbor in Hainan Island, South China. Using Illumina HiSeq sequencing, we observed substantial differences in the bacterial richness, diversity, and relative abundances of taxa between the two habitats, which were characterized differently in sediment type and nutrient status. Rhizospheric bacteria from sandy sediment at the eutrophic Xincun Bay were dominated by Desulfobacteraceae and Helicobacteraceae, which are primarily involved in sulfate cycling, whereas rhizosphere microbes from the reef flat at oligotrophic Tanmen Harbor were dominated by Vibrionaceae and Woeseiaceae, which may play important roles in nitrogen and carbon fixing. Additionally, we speculated that host-specific effects of these two seagrass species may be covered under nutrient-rich conditions and in mixed community patches, emphasizing the importance of the nutrient status of the sediment and vegetation composition of the patches. In addition, our study confirmed that Proteobacteria was more adapted to the rhizosphere environment than to lowcarbon conditions that occurred in bulk sediment, which was primarily dominated by well-known fermentative bacteria in the phylum Firmicutes.