Project description:By using a 44k chicken Agilent microarray, we systematically analyzed the chicken hypothalamus transcriptome response to thermal stress. Twelve hypothalamus samples were chosen from three groups (four samples per group) to be used in chicken genome microarray to examine differential gene expression.We compared the expression profiles between each pairs of the three groups using the microarray data. Totally, 2474 genes were found to be differentially expressed in the three comparisons with pM-oM-<M-^\0.05 and fold change (FC) higher than 1.5 and the genes were mainly involved in self-regulation and compensation required to maintain homeostasis, including heat shock protein family, enzyme and the hormone, neurotransmitter, cell-cell signaling, metabolism and cytokines. The transcripts of heat shock protein including Hsp 40 and Hsp 90 were significantly changed respond to thermal stress and genes involved in regulation of cell morphogenesis were significantly upregulated in heat stressed group with comparison to control and temperature recovery group. Additionally, the down-regulated genes in both heat stress and temperature recovery groups compared to control group were enriched in muscle organ development, striated muscle tissue development, cardiac muscle tissue development and muscle tissue development, which indicates that muscle development was inhibited during and in short-term after heat treatment. Most of genes dysregulated in heat stress group were found to be recovered in temperature recovery group, which confirmed their roles they could play in coping with heat stress. The present study provides a broader understanding of molecular mechanisms underlying the stress response in chicken and discovery of novel genes that are regulated in a thermal stress specific manner. Hypothalamus samples were collected from non-heat treated group (reared at 25C, used as control), 24h 34C treated group (heat stress treated group) and temperature recovery group (25C for 24h followed heat stress).

Project description:Background: Geographic variation in the thermal environment impacts a broad range of biochemical and physiological processes and can be a major selective force leading to local population adaptation. In the intertidal copepod Tigriopus californicus, populations along the coast of California show differences in thermal tolerance that are consistent with adaptation, i.e., southern populations withstand thermal stresses that are lethal to northern populations. To understand the genetic basis of these physiological differences, we use an RNA-seq approach to compare genome-wide patterns of gene expression in two populations known to differ in thermal tolerance. Results: Observed differences in gene expression between the southern (San Diego) and the northern (Santa Cruz) populations included both the number of affected loci as well as the identity of these loci. However, the most pronounced differences concerned the amplitude of up-regulation of genes producing heat shock proteins (Hsps) and genes involved in ubiquitination and proteolysis. Cuticle genes were up-regulated in SD but down-regulated in SC, and mitochondrial genes were downregulated in both populations. Among the hsp genes, orthologous pairs show markedly different thermal responses as the amplitude of hsp response was greatly elevated in the San Diego population, most notably in members of the hsp70 gene family. There was no evidence of accelerated evolution at the sequence level for hsp genes. Conclusions: Marked changes in gene expression were observed in response to acute sublethal thermal stress in the copepod T. californicus. Although some qualitative differences were observed between populations (e.g., cuticle gene regulation), the most pronounced differences involved the magnitude of induction of numerous hsp and ubiquitin genes. These differences in gene expression suggest that evolutionary divergence in the regulatory pathway(s) involved in acute temperature stress may offer at least a partial explanation of latitudinal trends in thermal tolerance observed in Tigriopus. For each population, ~600 copepods were split into two equal samples, one for control and one for treatment. Each sample was placed in a 50 mL Falcon tube containing 30 mL filtered seawater. After equilibrating samples to 20 degrees C, each tube was immersed in water bath at its target temperature (control: 20 C; treatment: 35 C) for one hour, and then immersed at 20 C for one hour for recovery. Copepods were then collected in a net mesh and quickly transferred to a tube containing 5 mL Tri-reagent for standard RNA extraction.

Project description:The expression of heat-shock proteins (Hsps) induced by a non-lethal heat treatment confers acquired thermotolerance (AT) to organisms against a subsequent challenge of otherwise lethal temperature. After stress signal lifted, AT gradually decayed with the decline of Hsps during recovery period. The duration of AT may be critical for sessile organisms, such as plants, to survive repeated heat stress in the environment. To identify heat-induced genes involved in duration of AT, we took a reverse-genetics approach by screening for Arabidopsis T-DNA insertion mutants that show decreased thermotolerance after a long recovery at non-stress condition following a conditioning treatment. Among the tested mutants corresponding to 47 genes, only the HsfA2 knockout mutant showed significant phenotype. The mutant plants were more sensitive to severe heat stress than the wild type after long but not short recovery following a pretreatment at 37oC, which can be complemented by introducing a wild-type copy of the gene. Quantitative hypocotyl elongation assay also revealed that AT decayed faster in the absence of HsfA2. Significant decline of the transcript levels of several highly heat-induced genes was observed in the HsfA2 knockout plants after a 4-h recovery or after 2 h of prolonged heat stress. Immunoblot anlysis showed that Hsa32 and class I small Hsp were lower in the mutant than in the wild type after a long recovery. Our results suggest that HsfA2 as a heat-induced transactivator sustains the post-stress expression of Hsp genes and extends the duration of AT in Arabidopsis. Experiment Overall Design: Total RNA was isolated from the seedlings of 5-d old wild-type and HsfA2 knockout mutant seedlings (a pool of about 100 plants per treatment in duplicates) harvested immediately after heat shock treatment. In this experiment, total 12 chips were used, 1 each for 2 biological replicates of the control and HS-treated samples for the wild type and mutant plants.

Project description:Background: Geographic variation in the thermal environment impacts a broad range of biochemical and physiological processes and can be a major selective force leading to local population adaptation. In the intertidal copepod Tigriopus californicus, populations along the coast of California show differences in thermal tolerance that are consistent with adaptation, i.e., southern populations withstand thermal stresses that are lethal to northern populations. To understand the genetic basis of these physiological differences, we use an RNA-seq approach to compare genome-wide patterns of gene expression in two populations known to differ in thermal tolerance. Results: Observed differences in gene expression between the southern (San Diego) and the northern (Santa Cruz) populations included both the number of affected loci as well as the identity of these loci. However, the most pronounced differences concerned the amplitude of up-regulation of genes producing heat shock proteins (Hsps) and genes involved in ubiquitination and proteolysis. Cuticle genes were up-regulated in SD but down-regulated in SC, and mitochondrial genes were downregulated in both populations. Among the hsp genes, orthologous pairs show markedly different thermal responses as the amplitude of hsp response was greatly elevated in the San Diego population, most notably in members of the hsp70 gene family. There was no evidence of accelerated evolution at the sequence level for hsp genes. Conclusions: Marked changes in gene expression were observed in response to acute sublethal thermal stress in the copepod T. californicus. Although some qualitative differences were observed between populations (e.g., cuticle gene regulation), the most pronounced differences involved the magnitude of induction of numerous hsp and ubiquitin genes. These differences in gene expression suggest that evolutionary divergence in the regulatory pathway(s) involved in acute temperature stress may offer at least a partial explanation of latitudinal trends in thermal tolerance observed in Tigriopus.

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Transcriptome responses to heat stress in hypothalamus of a meat-type chicken

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