MAPKAPK2 (MK2) is an important regulator of the p38 mitogen-activated protein kinase (p38 MAPK) pathway, which is involved in a plethora of cellular processes concluding the development of gamete cells in meiosis and resisting pathogenic bacterial infestation. Hyriopsis cumingii is a significant mussel resource in China and a good material for pearl breeding. To explore the role of MK2 in H. cumingii, MK2 was identified and cloned, whose full-length cDNA was 1568 bp, including 87 bp in 5′ UTR, 398 bp in 3′ UTR, and 1083 bp in the open reading frame (ORF) region, encoding 360 amino acids. The expression of MK2 was the highest in the gills. Meanwhile, there was a significant difference in the gonads. After Aeromonas hydrophila and Lipopolysaccharide (LPS) infestation, the transcript level of the MK2 was upregulated in the gills. It indicated that MK2 might be involved in the innate immune response of H. cumingii after a pathogenic attack. After quantifying H. cumingii of different ages, it was found that the expression of MK2 was highest at 1 year old. In situ hybridization (ISH) results showed that the blue-purple hybridization signal was very significant in the oocytes and egg membranes of the female gonads of H. cumingii. The expression of MK2 increased gradually at the age of 1 to 5 months and showed a downward trend at the age of 5 to 8 months. It was suggested that MK2 might play an important role in the formation of primitive germ cells in H. cumingii. To sum up, MK2 might not only be involved in the immune response against pathogenic bacterial infection but also might play an important role in the development of the gonads in H. cumingii.

Small extracellular vesicles were shown to have similar functional roles to their parent cells without the defect of potential tumorigenicity, which made them a great candidate for regenerative medicine. The last twenty years have witnessed the rapid development of research on small extracellular vesicles. In this paper, we employed a scientometric synthesis method to conduct a retrospective analysis of small extracellular vesicles in the field of bone-related diseases. The overall background analysis consisted the visualization of the countries, institutions, journals, and authors involved in research. The current status of the research direction and future trends were presented through the analysis of references and keywords, which showed that engineering strategies, mesenchymal stem cell derived exosomes, and cartilage damage were the most concerning topics, and scaffold, osteoarthritis, platelet-rich plasma, and senescence were the future trends. We also discussed the current problems and challenges in practical applications, including the in-sight mechanisms, the building of relevant animal models, and the problems in clinical trials. By using CiteSpace, VOSviewer, and Bibliometrix, the presented data avoided subjective selectivity and tendency well, which made the conclusion more reliable and comprehensive. We hope that the findings can provide new perspectives for researchers to understand the evolution of this field over time and to search for novel research directions.

This study investigated the effects of culture systems and feed types on the gut microbiota of mandarin fish (Siniperca chuatsi), using three production culture modes: pond–live bait (CE), pond–artificial feed (CS), and RAS–artificial feed (GS). Under identical pond culture conditions, CS fish fed compound feed had higher relative abundances of carbohydrate-metabolizing Bacteroidota and Firmicutes than CE. The CS group showed higher α-diversity, but β-diversity analysis indicated no significant community difference (p = 0.36), demonstrating that feed replacement only induced mild microbial shifts. LEfSe analysis uncovered 17 differential taxa: homeostasis-related genera enriched in CS, while the lipid-adapted Macellibacteroides prevailed in CE. Under identical artificial feed conditions, switching culture mode from pond (CS) to industrial RAS (GS) drastically reduced gut microbial diversity and simplified community structure. GS exhibited a sharp rise in Fusobacteriota, with Cetobacterium (64.94%) becoming the single dominant genus. α-diversity was lower in GS than CS, and β-diversity confirmed highly distinct community profiles between the two groups (p = 0.004). LEfSe detected 43 differential taxa with diverse metabolic genera abundant in CS. No PICRUSt2-inferred KEGG pathways remained significant after FDR correction in the above two comparison groups, so these functional trends are only for reference.

Rice–crab coculture, as China’s third-largest integrated farming model, is pivotal for sustainable Chinese mitten crab aquaculture. This study conducted untargeted metabolomics and 16S rRNA gene sequencing on gut contents of crabs from rice fields and ponds, integrating metabolic and microbial profiles. We aimed to reveal the chemical traits of rice-field Chinese mitten crab linked to gut microbiota, providing scientific guidance for optimizing culture practices and developing microbial additives. Both groups were dominated by the phyla Firmicutes, Proteobacteria, and Bacteroidota, but the phylum Bdellovibrionota was not detected in group R. A total of 1271 distinct amplicon sequence variants (ASVs) were identified, which were annotated to 649 genera. At the ASV level, the Chao1 index for the R group (197.12 ± 17.88) was notably lower compared to the P group (288.75 ± 30.59) (p < 0.01). In contrast, the Shannon index for the R group (3.90 ± 0.06) was significantly greater than that of the P group (3.70 ± 0.06) (p < 0.01). The PCA plot demonstrated a distinct discrimination between the groups. The P group had more microbial species but was dominated by Candidatus_Bacilloplasma, resulting in uneven distribution. In contrast, the R group had fewer species but a more balanced distribution. Among 3531 metabolites identified in both groups, 865 differed significantly. Compared to P, 736 metabolites were significantly upregulated and 129 were significantly downregulated in R. Key metabolic pathways included amino acid, carbohydrate, cofactor and vitamin metabolism, signaling, and xenobiotics biodegradation. Group R had higher levels of L-leucine, L-phenylalanine, L-tyrosine, 2-amino-1-phenylethanol, choline, and pyrophaeophorbide a, which correlated with genera like Candidatus_Hepatoplasma and Aeromonas (p < 0.05), suggesting better nutritional value, flavor, and metabolic health in rice-field crabs.