Project description:In this project, effects of chronic temperature changes on the transcriptome of the rainbow trout heart (Oncorhynchus mykiss) were examined. Ectothermic animals of north-temperate latitudes experience large seasonal changes in temperature which strongly affect the rate of body functions. To compensate for the effects of temperature changes ectotherms can respond to chronic temperature changes by increasing the quantity of tissue or enzyme needed for different physiological tasks, or by expressing proteins isoforms which are more appropriate for the new thermal conditions. On the other hand, proteins which are needed in lesser amounts in the new thermal regime could be depressed or down-regulated. Although expression of proteins can be changed by multiple mechanisms during synthesis and degradation, temperature dependent changes in transcription of genes is probably the most important factor in modifying the proteome of the tissues. Rainbow trout are active throughout their thermal tolerance range (0-25Â°C). Maintenance of adequate cardiac function at different thermal conditions requires a thorough change of the cardiac phenotype which appears as compensatory changes in relative heart mass, energy metabolism, nervous and humoral control of cardiac contractility and in electrical and mechanical properties of the trout heart. Such an extensive structural and functional remodeling of the heart probably necessitates both qualitative and quantitative changes among the numerous macromolecules which constitute the cardiac phenotype and cannot, therefore, be solely based on posttranslational modification of proteins but is expected to require differential gene expression. As a power supply of the circulatory system, the heart is in the focal point of physiological plasticity and sets limits for the activity level of the animal in different thermal conditions. Although several aspects of heart function have been studied in thermally acclimated fish and a number of structural changes have been noticed on exposure to different temperatures, the cellular and molecular mechanisms involved in chronic thermal stress of the fish heart are only partially elucidated. An interesting and poorly examined feature of the cold-acclimated phenotype of the trout heart is the increased heart mass which attenuates the depressive effect of low temperature on cardiac pump function. The heart is a complex organ composed of multiple tissues which together provide the system all necessary qualifications for cardiac pump function. In addition to the contractile and metabolic machinery of the cardiac myocytes, the amount and quality of the extracellular matrix also contribute to the properties of the heart as a muscular pump. Due to the complexity of the heart an enormous amounts of research efforts are needed to find out and examine all crucial aspects of cardiac plasticity required for thermal acclimation. In this regard the screening of gene expression by cDNA micro arrays might provide a broader view to genomic basis of cardiac remodeling under changing temperatures and aid to reveal the candidate genes which are important for thermal acclimation and which might remain unnoticed by traditional biochemical and physiological methods. In the present study we the steady-state effects of temperature acclimation on gene expression of the rainbow trout heart were screened by micro array analysis.

Project description:In this project, effects of chronic temperature changes on the transcriptome of the rainbow trout heart (Oncorhynchus mykiss) were examined. Ectothermic animals of north-temperate latitudes experience large seasonal changes in temperature which strongly affect the rate of body functions. To compensate for the effects of temperature changes ectotherms can respond to chronic temperature changes by increasing the quantity of tissue or enzyme needed for different physiological tasks, or by expressing proteins isoforms which are more appropriate for the new thermal conditions. On the other hand, proteins which are needed in lesser amounts in the new thermal regime could be depressed or down-regulated. Although expression of proteins can be changed by multiple mechanisms during synthesis and degradation, temperature dependent changes in transcription of genes is probably the most important factor in modifying the proteome of the tissues. Rainbow trout are active throughout their thermal tolerance range (0-25°C). Maintenance of adequate cardiac function at different thermal conditions requires a thorough change of the cardiac phenotype which appears as compensatory changes in relative heart mass, energy metabolism, nervous and humoral control of cardiac contractility and in electrical and mechanical properties of the trout heart. Such an extensive structural and functional remodeling of the heart probably necessitates both qualitative and quantitative changes among the numerous macromolecules which constitute the cardiac phenotype and cannot, therefore, be solely based on posttranslational modification of proteins but is expected to require differential gene expression. As a power supply of the circulatory system, the heart is in the focal point of physiological plasticity and sets limits for the activity level of the animal in different thermal conditions. Although several aspects of heart function have been studied in thermally acclimated fish and a number of structural changes have been noticed on exposure to different temperatures, the cellular and molecular mechanisms involved in chronic thermal stress of the fish heart are only partially elucidated. An interesting and poorly examined feature of the cold-acclimated phenotype of the trout heart is the increased heart mass which attenuates the depressive effect of low temperature on cardiac pump function. The heart is a complex organ composed of multiple tissues which together provide the system all necessary qualifications for cardiac pump function. In addition to the contractile and metabolic machinery of the cardiac myocytes, the amount and quality of the extracellular matrix also contribute to the properties of the heart as a muscular pump. Due to the complexity of the heart an enormous amounts of research efforts are needed to find out and examine all crucial aspects of cardiac plasticity required for thermal acclimation. In this regard the screening of gene expression by cDNA micro arrays might provide a broader view to genomic basis of cardiac remodeling under changing temperatures and aid to reveal the candidate genes which are important for thermal acclimation and which might remain unnoticed by traditional biochemical and physiological methods. In the present study we the steady-state effects of temperature acclimation on gene expression of the rainbow trout heart were screened by micro array analysis. Keywords: parallel sample

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:Photosystem II (PSII) is the most thermally sensitive component of photosynthesis. Thermal acclimation of this complex activity is likely to be critically important to the ability of photosynthetic organisms to tolerate temperature changes in the environment. We have analysed gene expression using whole-genome microarrays and monitored alterations in physiology during acclimation of PSII to elevated growth temperature in Synechocystis sp. PCC 6803. PSII acclimation is complete within 480 minutes of exposure to elevated temperature and is associated with a highly dynamic transcriptional response. 176 genes were identified and classified into seven distinct response profile groups. Response profiles suggest the existence of an early transient phase and a sustained phase to the acclimation response. The early phase was characterised by induction of general stress response genes, including heat shock proteins, which are likely to influence PSII thermal stability. The sustained phase consisted of acclimation-specific alterations that are involved in other cellular processes. Sustained responses included genes involved in phycobillisome structure and modification, photosynthesis, respiration, lipid metabolism and motility. Approximately 60% of genes with sustained altered expression levels have no known function. The potential role of differentially expressed genes in thermotolerance and acclimation is discussed. We have characterised the acclimation physiology of selected gene ‘knockouts’ to elucidate possible gene function in the response. All mutants show lower PSII rates under normal growth conditions. Basal PSII thermotolerance was affected by mutations in clpB1, cpcC2, hspA, htpG and slr1674. Final PSII thermotolerance was affected by mutations in cpcC2, hik34, hspA and hypA1, suggesting that these gene products play roles in long-term thermal acclimation of PSII. Gene expression levels were compared during a time-course (up to 8 hours) of thermal acclimation (from 25C to 38C) of a wild-type strain grown under continuous illumination and bubbled with CO2 -enriched air. Up to four independent biological replicates were generated and analysed. Each array: replicate matched time-point vs. 0hr control.

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