Project description:We utilized a candidate gene approach using custom microarray constructed for our study species Drosophila montana and D. virilis to identify genes with modulated expression patterns under low temperature conditions. The flies were exposed to four different treatments (+5°C for 6 days, 0°C for 1 hour, two periods of recovery after cold stress and a control treatment). The aim of the study was to identify potential cold-responsive genes and to investigate differences in gene expression between the species. Microarray analysis revealed altogether 31 out of 219 genes on the array to show expression changes during different stages of cold stress. Among the potential stress tolerance genes detected earlier in D. melanogaster, hsr-omega was upregulated in both species during cold acclimation, expression changes in other genes being treatment- and species specific. Our microarray study clearly showed that different stages of cold response elicit changes at least in genes involved in heat shock response, circadian rhythm and metabolism. Cold- induced gene expression was investigated comparing four different treatments to the control treatment: 1) Cold acclimation: 14 days in control conditions, then 6 days at +5°C 2) Cold hardening: 20 days in control conditions, then1 hour at 0°C 3) 15-min recovery from chill coma: the 20-day-old flies were exposed to -6°C for 16 hours, after which they were let to recover for 15 minutes 4) 1-hour recovery from chill coma: the 20-day-old flies were exposed to -6°C for 16 hours, after which they were let to recover for 1 hour. In control treatment flies were kept for 20 days at 19°C. All the flies were 20-days old at the time of sample collection, and the light:dark cycle was 22 hours of light and 2 hours of dark. Because of the limited space on the array plate, the recovery samples were collected only for D. montana. All the samples were collected 5-6 hours after the lights had been turned on in the chamber and the flies were immediately immersed in liquid nitrogen, after which they were stored at -84ºC. Three pools of ten flies were collected from each treatment group.

Project description:During cold acclimation plants increase their freezing tolerance in response to low non-freezing temperatures. This is accompanied by many physiological, biochemical and molecular changes that have been extensively investigated. In addition, many cold acclimated plants become more freezing tolerant during exposure to mild, non-damaging sub-zero temperatures. There is hardly any information available about the molecular basis of this adaptation. However, Arabidopsis thaliana is among the species that acclimate to sub-zero temperatures. This makes it possible to use the molecular and genetic tools available in this species to identify components of sub-zero signal transduction and acclimation. Here, we have used microarrays and a qRT-PCR primer platform covering 1880 genes encoding transcription factors to monitor changes in gene expression in the accessions Columbia-0, Rschew and Tenela during the first three days of sub-zero acclimation at -3°C. The results indicate that gene expression during sub-zero acclimation follows a tighly controlled time-course. Especially AP2/EREBP and WRKY transcription factors may be important regulators of sub-zero acclimation, although the CBF signal transduction pathway seems to be less important during sub-zero than during cold acclimation. Globally, we estimate that approximately 5% of all Arabidopsis genes are regulated during sub-zero acclimation. Particularly photosynthesis-related genes were down-regulated and genes belonging to the functional classes of cell wall biosynthesis, hormone metabolism and RNA regulation of transcription were up-regulated. Collectively, these data provide the first global analysis of gene expression during sub-zero acclimation and allow the identification of candidate genes for forward and reverse genetic studies into the molecular mechanisms of sub-zero acclimation. We used whole genome microarrays to monitor changes in gene expression in the Arabidopsis thaliana accessions Columbia-0, Rschew and Tenela during three days of acclimation to sub-zero temperature at -3°C after cold acclimation

Project description:During cold acclimation plants increase their freezing tolerance in response to low non-freezing temperatures. This is accompanied by many physiological, biochemical and molecular changes that have been extensively investigated. In addition, many cold acclimated plants become more freezing tolerant during exposure to mild, non-damaging sub-zero temperatures. There is hardly any information available about the molecular basis of this adaptation. However, Arabidopsis thaliana is among the species that acclimate to sub-zero temperatures. This makes it possible to use the molecular and genetic tools available in this species to identify components of sub-zero signal transduction and acclimation. Here, we have used microarrays and a qRT-PCR primer platform covering 1880 genes encoding transcription factors to monitor changes in gene expression in the accessions Columbia-0, Rschew and Tenela during the first three days of sub-zero acclimation at -3°C. The results indicate that gene expression during sub-zero acclimation follows a tighly controlled time-course. Especially AP2/EREBP and WRKY transcription factors may be important regulators of sub-zero acclimation, although the CBF signal transduction pathway seems to be less important during sub-zero than during cold acclimation. Globally, we estimate that approximately 5% of all Arabidopsis genes are regulated during sub-zero acclimation. Particularly photosynthesis-related genes were down-regulated and genes belonging to the functional classes of cell wall biosynthesis, hormone metabolism and RNA regulation of transcription were up-regulated. Collectively, these data provide the first global analysis of gene expression during sub-zero acclimation and allow the identification of candidate genes for forward and reverse genetic studies into the molecular mechanisms of sub-zero acclimation. We used whole genome microarrays to monitor changes in gene expression in the Arabidopsis thaliana accessions Columbia-0, Rschew and Tenela during three days of acclimation to sub-zero temperature at -3°C after cold acclimation Plants from Arabidopsis thaliana accessions Columbia-0, Rschew and Tenela were cold acclimated at 4°C for two weeks. Detached leaves were then sub-zero acclimated at -3°C for 8 h, 1 d or 3 d at -3°C. Leaves of cold acclimated plants and sub-zero acclimated leaves were collected for RNA extraction and hybridization on Affymetrix ATH1 microarrays in order to explore temporal transcriptome changes during sub-zero acclimation. For each sample total RNA was isolated from a pool of three leaves from three different plants. The experiment was performed in three idenpendent biological replicates.

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Transcriptome changes associated with cold acclimation in two species of the Drosophila virilis group

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