Elevated temperatures reduce population‐specific transcriptional plasticity in developing lake sturgeon (Acipenser fulvescens)

Abstract

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.

Timing-specific parental effects of ocean warming in a coral reef fish

“…The exposure to elevated temperature during reproduction, which in our experiment also coincided with embryogenesis, indeed caused a marked reduction in the expression of genes involved in protein synthesis and mitochondrial ATP production in the offspring. Similar effects were found in lake sturgeons, Acipenser fulvescens, exposed to increased water temperature during early development, a critical life stage in this species [76]. In our study, translation and cellular respiration suppression were accompanied by upregulation of genes indicating heat-induced ER stress owing to the accumulation of unfolded or misfolded proteins in the ER.…”

Timing specific parental effects of ocean warming in a coral reef fish

“…While parental developmental thermal exposure caused trade-offs between costs and benefits of thermal acclimation in the offspring, the exposure to elevated temperature during reproduction, which in our experiment coincided with both gametogenesis and embryo development, was always detrimental for the offspring, and caused a marked reduction in expression of genes involved in protein synthesis and mitochondrial ATP production. Similar effects were recently found in populations of lake sturgeon, Acipenser fulvescens , exposed to increased water temperature during early development, a critical life stage in this species (Bugg, Thorstensen, Marshall, Anderson, & Jeffries, 2023). In our study, translation and cellular respiration suppression were accompanied by upregulation of several genes indicating heat-induced endoplasmic reticulum (ER) stress due to accumulation of unfolded or misfolded proteins in the ER.…”

Integrated organismal responses induced by ecologically-relevantpCO2and temperature exposures in developing lake sturgeon

“…While researchers may expect adaptations to CO 2 flucuations in freshwater organisms 2,3,7 , this variability has nevertheless been shown to induce physiological responses in the lake sturgeon and other species 1 . Lake sturgeon, like other sturgeons, exhibit exceptional phenotypic plasticity to various environmental stressors [47][48][49] . This high plasticity makes sturgeons valuable for studying responses to environmental change at multiple biological scales, while their status as an ancient fish enables analyses of potentially conserved traits 50 .…”