College of Animal Science and Technology, Sichuan Agricultural University, Chengdu, Sichuan, 611130, China.
Fish Shellfish Immunol. 2024 Nov;154:109918. doi: 10.1016/j.fsi.2024.109918. Epub 2024 Sep 21.
Gill remodeling is an important strategy for fish to cope with hypoxia, and many of the teleost possess this ability, but the underlying mechanism is not well understood. To investigate the mechanism of hypoxia-induced gill remodeling, largemouth bass (Micropterus salmoides) exposed to hypoxia (dissolved oxygen level: 2.0 ± 0.2 mg L) for 7 days, followed by 7 days of reoxygenation. Hypoxia tests were also performed on primary gill cells from largemouth bass. We found that hypoxia-induced gill remodeling increased the respiratory surface area of the gills. This change in gill morphology was reversible and recovered after reoxygenation. A reduction in the number of mucous cells and rearrangement of mitochondria-rich cells (MRCs) were observed during gill remodeling. After 7 days of reoxygenation, the number of mucous cells and the position of the MRCs were restored. Hypoxia resulted in a 2.92-fold increase in the number of primary gill cells that underwent migration over a 12-h period. The mRNA levels of nine integrin subunits (α1, α2, α5, α7, α8, α10, αL, β1 and β2) were significantly up-regulated after 12 h of hypoxia in vivo, and the changes in the expression of these subunits were consistent with the HIF-1α trend. Immunohistochemistry showed that integrin β1 protein levels were significantly increased and were abundantly expressed in the interlamellar cell mass after exposure to hypoxia. Taken together, the results of the present study demonstrated that changes in mucosal cells and MRCs play an important role in hypoxia-induced gill remodeling in largemouth bass and that these changes are regulated by integrins.
鳃重塑是鱼类应对低氧的重要策略，许多硬骨鱼类都具有这种能力，但其中的机制尚不清楚。为了研究低氧诱导的鳃重塑机制，本研究将大口黑鲈（Micropterus salmoides）暴露于低氧（溶解氧水平：2.0±0.2mg/L）中 7 天，随后进行 7 天的复氧。同时还在大口黑鲈的原代鳃细胞上进行了低氧实验。结果发现，低氧诱导的鳃重塑增加了鳃的呼吸表面积。这种鳃形态的变化是可逆的，在复氧后会恢复。在鳃重塑过程中观察到黏液细胞数量减少和富含线粒体的细胞（MRCs）的重新排列。复氧 7 天后，黏液细胞的数量和 MRC 的位置得到了恢复。低氧导致在 12 小时的迁移过程中，有 2.92 倍数量的原代鳃细胞发生迁移。在体内低氧 12 小时后，9 种整合素亚基（α1、α2、α5、α7、α8、α10、αL、β1 和β2）的 mRNA 水平显著上调，这些亚基的表达变化与 HIF-1α的趋势一致。免疫组织化学显示，整合素β1 蛋白水平在暴露于低氧后显著增加，并在板间细胞群中大量表达。综上所述，本研究结果表明，黏膜细胞和 MRCs 的变化在大口黑鲈低氧诱导的鳃重塑中发挥重要作用，这些变化受整合素调节。
