Department of Biological Sciences, University of Manitoba, Winnipeg, Manitoba, Canada.
Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada.
Mol Ecol. 2023 Jul;32(14):4044-4062. doi: 10.1111/mec.16967. Epub 2023 May 7.
Rising mean and variance in temperatures elevates threats to endangered freshwater species such as lake sturgeon, Acipenser fulvescens. Previous research demonstrated that higher temperatures during development result in physiological consequences for lake sturgeon populations throughout Manitoba, Canada, with alteration of metabolic rate, thermal tolerance, transcriptional responses, growth and mortality. We acclimated lake sturgeon (30-60 days post fertilization, a period of high mortality) from northern and southern populations (56°02'46.5″N, 96°54'18.6″W and 50°17'52″N, 95°32'51″W, respectively, separated by approximately 650 km) within Manitoba to current (summer highs of 20-23°C) and future projected (+2-3°C) environmental temperatures of 16, 20 and 24°C for 30 days, and we measured gill transcriptional responses using RNAseq. Transcripts revealed SNPs consistent with genetically distinct populations and transcriptional responses altered by acclimation temperature. There were a higher number of differentially expressed transcripts observed in the southern, compared to the northern, population as temperatures increased, indicating enhanced transcriptional plasticity. Both lake sturgeon populations responded to elevated acclimation temperatures by downregulating the transcription of genes involved in protein synthesis and energy production. Furthermore, there were population-specific thresholds for the downregulation of processes promoting transcriptional plasticity as well as mitochondrial function as the northern population showed decreases at 20°C, while this capacity was not diminished until 24°C in the southern population. These transcriptional responses highlight the molecular impacts of increasing temperatures for divergent lake sturgeon populations during vulnerable developmental periods and the critical influence of transcriptome plasticity on acclimation capacity.
温度的均值和方差上升，增加了淡水濒危物种如湖鲟（Acipenser fulvescens）的威胁。先前的研究表明，在加拿大马尼托巴省，发育过程中的较高温度会对湖鲟种群产生生理影响，改变代谢率、热耐受性、转录反应、生长和死亡率。我们将来自北部和南部种群（北纬 56°02'46.5"，西经 96°54'18.6"和北纬 50°17'52"，西经 95°32'51"，相隔约 650 公里）的湖鲟（受精后 30-60 天，这段时间死亡率较高）适应于当前（夏季高温 20-23°C）和未来预测的（+2-3°C）环境温度 16、20 和 24°C 30 天，并使用 RNAseq 测量了鳃转录反应。转录本显示与遗传上不同种群一致的 SNPs，并因适应温度而改变转录反应。随着温度的升高，南部种群的差异表达转录本数量高于北部种群，表明转录可塑性增强。两个湖鲟种群都对升高的适应温度做出反应，下调参与蛋白质合成和能量产生的基因转录。此外，下调促进转录可塑性和线粒体功能的过程存在种群特异性阈值，因为北部种群在 20°C 时表现出下降，而南部种群直到 24°C 时才出现这种情况。这些转录反应突出了不断上升的温度对脆弱发育阶段不同湖鲟种群的分子影响，以及转录组可塑性对适应能力的关键影响。
