Structural modifications in the gill membranes maintain homeostasis under the influence of temperature changes. We hypothesized that thermal acclimation would result in significant modification of phospholipid fatty acids, with modulation of sodium pump activity during acute (24 and 48 h) and chronic (15 days) thermal shifts in the neotropical reophilic catfish Steindachneridion parahybae. Indeed, the time-course experiment showed acute and chronic changes in gill membrane at the lowest temperatures, notably linked to maintenance of membrane fluidity: significant preferential changes in phosphatidylethanolamine, with decrease of saturated fatty acids and increase of C18:1 in all groups kept below 30 °C in chronic trial, increase in polyunsaturated fatty acids n6 and C18:1 at 17 and 12 °C compared to 24 °C, as soon as the temperature was changed (initial time). Additionally, the activity of the sodium pump increased at 12 °C, but without apparent connection with the altered lipid environment. The animals maintained at the lowest temperature showed a higher mortality, possibly because of the approach to the minimum critical temperature for this species, and unexpected results of changes in the fatty acid profile, such as decreased docosahexaenoic acid in phosphatidylethanolamine and increased saturated fatty acids in phosphatidylcholine. This set of mechanisms highlights rheostatic adjustments in this species in the face of temperature changes.

鳃膜的结构改变在温度变化的影响下保持体内平衡。我们假设热驯化会导致磷脂脂肪酸的显着改变，在新热带嗜湿鲶鱼Steindachneridion parahybae 的急性（24 和 48 小时）和慢性（15 天）热变化期间调节钠泵活性. 事实上，时间过程实验表明，在最低温度下鳃膜的急性和慢性变化，特别是与膜流动性的维持有关：磷脂酰乙醇胺的显着优先变化，所有组中饱和脂肪酸的减少和 C18:1 的增加保持在长期试验中低于 30°C，一旦温度改变（初始时间），多不饱和脂肪酸 n6 和 C18:1 在 17°C 和 12°C 与 24°C 相比增加。此外，钠泵的活性在 12°C 时增加，但与改变的脂质环境没有明显联系。维持在最低温度的动物死亡率更高，可能是因为接近该物种的最低临界温度，以及脂肪酸谱变化的意外结果，例如降低磷脂酰乙醇胺中的二十二碳六烯酸和增加磷脂酰胆碱中的饱和脂肪酸。这套机制突出了该物种在面对温度变化时的变阻调整。