Research
| Title： | Effects of temperature stress on intestinal tissues, immune response, intestinal microbiota, and inflammation in juvenile largemouth bass (Micropterus salmoides) |
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| First author： | Tian, Mengping; Zhao, Shasha; Zhu, Xiaoming; Han, Dong; Zhang, Lei |
| Journal： | AQUACULTURE |
| Years： | 2026 |
| DOI： | 10.1016/j.aquaculture.2025.743051 |
| Abstract： | The fish intestine acts as a barrier in response to stress from the external environment. Largemouth bass (Micropterus salmoides) is a widely farmed economically important fish species. Juvenile largemouth bass are highly sensitive to temperature changes. Still, little is known about the effects of temperature stress on the immune function and the response of the intestinal microbiota in juvenile largemouth bass. To evaluate the effects of temperature stress on intestinal histology, immune response, microbiota, and inflammation of juvenile largemouth bass, this study comprised four treatment groups: 24 degrees C (the light cold-stress group), 27 degrees C (the optimal temperature group), 30 degrees C (the light heat-stress group), and 33 degrees C (the severe heat-stress group). The results indicated that the intestinal tissues of juvenile largemouth bass were damaged by temperature stress. The temperature-stress groups showed a significant decrease in the protein levels of MUC2, ZO-1, and Occludin, indicating that temperature stress damages the intestinal mucosal layer and tight junction structures. Heat stress increased the activities of immune-related enzymes, and the temperature-stress groups exhibited significantly higher levels of CD4, MPO, and immune-related genes, indicating damage to the intestinal immune barrier. Besides, the temperature-stress groups demonstrated elevated expression levels of inflammatory and apoptotic genes, and the corresponding protein levels were also significantly increased. The relative abundance of beneficial bacteria in the intestinal microbiota increased, while the presence of opportunistic pathogens decreased under temperature stress. The changes in the relative abundance of intestinal microbiota were significantly correlated with immune-related enzymes, inflammatory genes, and apoptotic genes. These findings indicate that temperature stress can damage the intestinal physical barrier of juvenile largemouth bass, disrupt the structure and species composition of the intestinal microbiota, and potentially impair the functioning of the intestinal immune barrier. The results of this study will increase our understanding of the underlying mechanisms of the intestinal immune response to ambient temperature stress in temperature-sensitive juvenile fish. |
