Project description:Intertidal zone organisms can experience transient freezing temperatures during winter low tides, but their extreme cold tolerance mechanisms are not known. Petrolisthes cinctipes is a temperate mid-high intertidal zone crab species that can experience wintertime habitat temperatures below the freezing point of seawater. We examined how cold tolerance changed during the initial phase of thermal acclimation to cold and warm temperatures, as well as the persistence of cold tolerance during long-term thermal acclimation. Thermal acclimation for as little as 6 hours at 8˚C enhanced crab tolerance during a 1h exposure to -2°C relative to crabs acclimated to 18˚C. Potential mechanisms for this enhanced tolerance were elucidated using cDNA microarrays to probe for differences in gene expression in cardiac tissue of warm and cold acclimated crabs during the first day of thermal acclimation. No changes in gene expression were detected until 12h of thermal acclimation. Genes strongly upregulated in warm acclimated crabs represented immune response and extracellular / intercellular processes, suggesting that warm acclimated crabs had a generalized stress response and may have been remodelling tissues or altering intercellular processes. Genes strongly upregulated in cold acclimated crabs included many that are involved in glucose production suggesting that cold acclimation involves increasing intracellular glucose as a cryoprotectant. Structural cytoskeletal proteins were also strongly represented among the genes upregulated in only cold acclimated crabs. There were no consistent changes in composition or the level of unsaturation of membrane phospholipid fatty acids with cold acclimation, which suggests that neither short- nor long-term changes in cold tolerance are mediated by changes in membrane fatty acid composition. Overall, our study demonstrates that initial changes in cold tolerance are likely not regulated by transcriptomic responses, but that gene expression-related changes in homeostasis begin within 12 hours – the length of a tidal cycle. all array data and raw images archived at the Porcelain Crab Array Database (http://array.sfsu.edu)

Project description:Coral bleaching has devastating effects on coral survival and reef ecosystem function, but many of the fundamental cellular effects of thermal stress on cnidarian physiology are unclear. We used label-free liquid chromatography-tandem mass spectrometry to assess the effects of high temperatures on the proteome of the model symbiotic anemone Aiptasia sp. Anemones were acclimated to elevated temperatures (30 °C and 33.5 °C) for two weeks or exposed to short-term thermal shock (33.5 °C, 24 hours) without acclimation. We identified 2,137 protein clusters in Aiptasia, 136 of which were differentially abundant between treatments. There were minimal differences (nine proteins) in protein abundances between the control (25 °C) and acclimated high-temperature (30 °C and 33.5 °C) treatments, indicating that thermal acclimation in symbiotic cnidarians is not primarily regulated at the level of protein expression. Heat shock resulted in significant changes in the abundance of 104 proteins, including those involved in protein folding and synthesis, redox homeostasis, and central metabolism. Nineteen highly abundant cytoskeletal and structural proteins showed particularly reduced abundance (approximately 50%), demonstrating proteostasis disruption and inhibition of protein synthesis. Heat shock induced proteins involved in multiple mechanisms for stabilizing nascent proteins, preventing protein aggregation and degrading damaged proteins, indicative of endoplasmic reticulum stress. Antioxidant mechanisms and metabolic enzymes necessary for redox homeostasis were also upregulated. Disruption of host proteostasis occurred before either bleaching or symbiont photoinhibition was detected, strongly suggesting endogenous reactive oxygen species production as the proximate cause of thermal damage. The effects of thermal shock were most pronounced at the endoplasmic reticulum, and proteostasis maintenance and protein turnover mechanisms may be essential in the response to severe thermal stress in symbiotic cnidarians.

Project description:Intertidal zone organisms can experience transient freezing temperatures during winter low tides, but their extreme cold tolerance mechanisms are not known. Petrolisthes cinctipes is a temperate mid-high intertidal zone crab species that can experience wintertime habitat temperatures below the freezing point of seawater. We examined how cold tolerance changed during the initial phase of thermal acclimation to cold and warm temperatures, as well as the persistence of cold tolerance during long-term thermal acclimation. Thermal acclimation for as little as 6 hours at 8˚C enhanced crab tolerance during a 1h exposure to -2°C relative to crabs acclimated to 18˚C. Potential mechanisms for this enhanced tolerance were elucidated using cDNA microarrays to probe for differences in gene expression in cardiac tissue of warm and cold acclimated crabs during the first day of thermal acclimation. No changes in gene expression were detected until 12h of thermal acclimation. Genes strongly upregulated in warm acclimated crabs represented immune response and extracellular / intercellular processes, suggesting that warm acclimated crabs had a generalized stress response and may have been remodelling tissues or altering intercellular processes. Genes strongly upregulated in cold acclimated crabs included many that are involved in glucose production suggesting that cold acclimation involves increasing intracellular glucose as a cryoprotectant. Structural cytoskeletal proteins were also strongly represented among the genes upregulated in only cold acclimated crabs. There were no consistent changes in composition or the level of unsaturation of membrane phospholipid fatty acids with cold acclimation, which suggests that neither short- nor long-term changes in cold tolerance are mediated by changes in membrane fatty acid composition. Overall, our study demonstrates that initial changes in cold tolerance are likely not regulated by transcriptomic responses, but that gene expression-related changes in homeostasis begin within 12 hours – the length of a tidal cycle. all array data and raw images archived at the Porcelain Crab Array Database (http://array.sfsu.edu) n=264 specimens were divided into warm (18°C, n=96), cold (8°C, n=96), and control (13°C, n=72) acclimation groups. Crabs were sampled from the 13°C group at 0 h (the start of the experiment) and 24 h, the termination of the experiment. Crabs were sampled from the warm and cold acclimation groups at 6, 12, 18, and 24 hours following the start of thermal acclimation. At each time point, heart tissue from n=16 crabs from each group was dissected, flash frozen and stored at −80°C. A pooled total aRNA sample was prepared for each group by mixing equal quantities of total RNA from n=5 individuals in each group in order to have the same amount of biological diversity within each pooled RNA sample. For microarray hybridizations we used n=25 slides in an incomplete loop design where each sample was hybridized n=5 times, 2-3 times labelled with each Cy dye

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Microbiome mediated plasticity promotes thermal adaptation in Nematostella vectensis

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