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In recent years, golden tides caused by floating Sargassum have induced severe ecological disasters globally. Eutrophication is a significant factor contributing to the massive spread of Sargassum golden tides. Furthermore, the thalli of Sargassum that float on the ocean surface are subjected to more ultraviolet radiation (UVR). The coupled impact of eutrophication and UVR on the photosynthetic physiology of golden tide species remains unclear. In this study, the thalli of Sargassum horneri, known to cause golden tide, were cultured and acclimated to three distinct nitrogen (N) conditions (natural seawater, NSW; NH4+-N enrichment; and NO3–N enrichment) for 6 days. Subsequently, the thalli were exposed to two different radiation treatments (photosynthetically active radiation (150 W m-2), PAR, 400–700 nm; PAR (150 W m-2) + UVR (28 W m-2), 280–700 nm) for 120 min, to investigate the photosynthetic effects of UVR and N on this alga. The findings demonstrated that exposure to UVR impeded the photosynthetic capacity of S. horneri, as evidenced by a decrease in the maximum photochemical quantum yield (Fv/Fm), photosynthetic efficiency (α) and chlorophyll content. Under diverse N-enrichment conditions, the alga tended to adopt various strategies to mitigate the adverse effects of UVR. NH4+-enrichment dissipated excess UVR energy through a greater increase in non-photochemical quenching (NPQ). While NO3–enrichment protected alga by enhancing N assimilation (higher nitrate reductase activity (NRA) and soluble protein content), and maintained a stable energy captured per unit reaction center for electron transfer (ET0/RC) and a higher net photosynthetic rate. Although different N enrichments could not completely offset the damage caused by UV radiation, they secured the photoprotective ability of S. horneri in several ways.

The potential role of peroxisome proliferator-activated receptor (PPAR) in regulating the biosynthesis of long-chain polyunsaturated fatty acids (LCPUFA) has not been explored in marine gastropod. In this study, we identified and characterized a PPAR gene from the abalone species Haliotis discus hannai Ino. This gene encodes a peptide consisting of 469 amino acids and comprises typical four domains: A/B domain, DNA-binding domain, D domain, and ligand-binding domain. Highest homology with that of the Patella depressa (51.08 %) from multiple alignments and phylogenetic tree analyses revealed it is a direct orthologue of the vertebrate PPAR. Tissue distribution analysis demonstrated that PPAR was highly expressed in muscle and gill, with lower expression observed in the kidney, female gonad, and hepatopancreas. Dual-luciferase reporter assays indicated that abalone PPAR significantly up-regulated the promoter activity of Δ5 fatty acyl desaturase (Δ5fad), a crucial enzyme in LCPUFA biosynthesis. Furthermore, C18PUFA significantly increased the expressions of Δ5fad and PPAR in the hepatopancreas of abalone compared to the control group fed with an LCPUFA-rich diet. These findings suggest that PPAR acts as a positive transcription factor for the fad gene, contributing to the transcriptional regulation of LCPUFA biosynthesis in abalone.

Based on 4 cruises in August and October 2018, February and May 2019,water quality and zooplankton at 59 stations in Miaodao Archipelago were investigated. The community structure, spatial and temporal distribution of zooplankton collected by type I net and the correlation with various environmental factors were analyzed statistically. The results showed that: a total of 93 species of zooplankton were identified in Miaodao Archipelago, including 13 categories, the species of copepods and planktonic larvae were 25 respectively, accounting for 53.8% in total. The dominant species in different seasons were different, and Calanus sinicus was dominant in all seasons. The abundance of zooplankton ranged from 3.0 to 2 720 ind/m3, with an average of 122.41 ind/m3, and the biomass ranged from 0.25 to 3 106.75 mg/m3, with an average of 172.15 mg/m3. The Shannon-Wiener index varied from 0.058 to 3.670, with an average of 1.431, the Pielou evenness index varied from 0.030 to 0.922, with an average of 0.467, and the Margalef index varied from 0.362 to 7.964, with an average of 2.358. The results of Pearson correlation analysis and canonical correspondence analysis showed that the distribution of zooplankton was influenced by various environmental factors, among which temperature and salinity were the most important factors.

Sepia esculenta is a cephalopod widely distributed in the Western Pacific Ocean, and there has been growing research interest due to its high economic and nutritional value. The limited anti-stress capacity of larvae renders challenges for their adaptation to high ambient temperatures. Exposure to high temperatures produces intense stress responses, thereby affecting survival, metabolism, immunity, and other life activities. Notably, the molecular mechanisms by which larval cuttlefish cope with high temperatures are not well understood. As such, in the present study, transcriptome sequencing of S. esculenta larvae was performed and 1,927 differentially expressed genes (DEGs) were identified. DEGs were subjected to functional enrichment analyses using the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases. The top 20 terms of biological processes in GO and 20 high-temperature stress-related pathways in KEGG functional enrichment analysis were identified. A protein-protein interaction network was constructed to investigate the interaction between temperature stress-related genes. A total of 30 key genes with a high degree of participation in KEGG signaling pathways or protein-protein interactions were identified and subsequently validated using quantitative RT-PCR. Through a comprehensive analysis of the protein-protein interaction network and KEGG signaling pathway, the functions of three hub genes (HSP90AA1, PSMD6, and PSMA5), which belong to the heat shock protein family and proteasome, were explored. The present results can facilitate further understanding of the mechanism of high temperature resistance in invertebrates and provide a reference for the S. esculenta industry in the context of global warming.