Project description:Cold hardening treatment, a brief exposure to low temperatures (e.g. 0°C for 2 h), can protect certain insects against subsequent exposure to temperatures sufficiently low to cause damage or lethality. Microarray analysis to examine the changes in transcript abundance associated with cold hardening has been undertaken in Drosophila melanogaster in order to gain insight into this phenomenon. Transcripts associated with 36 genes were identified, a subset of which appeared to be also differentially expressed after heat shock treatment. Quantitative RT-PCR was used to independently determine transcript abundance of a subset of these sequences. Taken together, these assays suggest that stress proteins, including Hsp23, Hsp26, Hsp83 and Frost as well as membrane-associated proteins may contribute to the cold hardening response. Keywords: cold stress response
Project description:Cold hardening treatment, a brief exposure to low temperatures (e.g. 0°C for 2 h), can protect certain insects against subsequent exposure to temperatures sufficiently low to cause damage or lethality. Microarray analysis to examine the changes in transcript abundance associated with cold hardening has been undertaken in Drosophila melanogaster in order to gain insight into this phenomenon. Transcripts associated with 36 genes were identified, a subset of which appeared to be also differentially expressed after heat shock treatment. Quantitative RT-PCR was used to independently determine transcript abundance of a subset of these sequences. Taken together, these assays suggest that stress proteins, including Hsp23, Hsp26, Hsp83 and Frost as well as membrane-associated proteins may contribute to the cold hardening response. Co-reared flies were separated into a control group and a treatment group at random. RNA was isolated from the cold-shocked flies and the respective controls and was used for direct comparisons on cDNA microarrays. Treatments were not varied as they had been optimized in previous studies. A pilot experiment was performed using the Drosophila 7k2 array (GPL311) and subsequently three pairs of independent biological samples were evaluated with the Drosophila 12k1 array (GPL1467).
Project description:In the field, insects suffer multiple cold exposures during winter. When exposed to repeated low temperatures, Drosophila melanogaster females showed an increase in survival, but a reduction in reproduction. In this study, the microarrays were used to analyze the gene expression of female D. melanogaster after multiple, single sustained (or single prolonged) and single short cold treatments, which exposed the flies at 0 M-0C for repeated 2 h, single 10 h and single 2 h respectively. Candidate genes that were involved in 6 h recovery from different types of cold exposures were identified. After repeated cold exposures, candidates particularly included genes involved in muscle protein and muscle activity. Stress-related genes, Turandot A, Turandot C, and Turandot M were up-regulated in response to multiple cold exposures, and improve the cold survival in female D. melanogaster. This work also suggested a strong relationship between cold exposure and the immune system. I suggest that in fruit flies, chilling injuries after cold exposure may induce immune responses and contribute to recovery from cold.
Project description:A study evaluating the effect of stress resistance selection of Drosophila melanogaster. Abstract Here, we report a detailed analysis of changes in gene expression in Drosophila melanogaster selected for multiple eological relevant environmental stress resistance traits. We analyzed females from three biological replicates from seven selection regimes and one control regime using whole genome gene expression arrays. Replicated selection lines were selected for resistance to acute heat survival, high temperature knock down, constant 30°C during development, cold shock survival, desiccation and starvation, respectively. Additionally, a set of replicated lines was selected for increased longevity. When compared to gene expression profiles of control lines, we were able to detect consistent selection responses at the transcript level in each specific selection regime and also found a group of differentially expressed genes that were generally changed among all selected lines. Replicated selection lines clustered together, i.e. showed similar changes in gene expression (compared to controls) and thus showed that 10 generations of artificial selection gives a clear signal among gene expression profiles. The changes in gene expression in lines selected for increased longevity, desiccation and starvation resistance, respectively, showed high similarities. Cold resistance selected lines showed little differentiation from controls. Different methods of heat selection (heat survival, heat knock down and constant 30°C) showed little similarity verifying that different mechanism are involved in high temperature adaptation. The direction of change in gene expression in the selected lines showed a consistent pattern for each selection regime. For most selection regimes and in the comparison of all selected lines and controls exclusively up- or down regulation of gene expression among significant differentially expressed genes was found. The different responses to selection expressed in individual selection regimes and among all selected lines indicate that we have identified genes involved in stress specific and general stress response mechanisms. Keywords: control versus selected
Project description:Transcriptome analysis may provide means to investigate the underlying genetic causes of shared and divergent phenotypes in different populations and help to identify potential targets of adaptive evolution. Applying RNA sequencing to whole male Drosophila melanogaster from the ancestral tropical African environment and a very recently colonized cold-temperate European environment at both standard laboratory conditions and following a cold shock, we seek to uncover the transcriptional basis of cold adaptation. In both the ancestral and the derived populations, the predominant characteristic of the cold shock response is the swift and massive upregulation of heat shock proteins and other chaperones. Although we find ~30% of the genome to be differentially expressed following a cold shock, only relatively few genes (n=26) are up- or down-regulated in a population-specific way. Intriguingly, 24 of these 26 genes show a greater degree of differential expression in the African population. Likewise, there is an excess of genes with particularly strong cold-induced changes in expression in Africa on a genome-wide scale. The analysis of the transcriptional cold shock response most prominently reveals an upregulation of components of a general stress response, which is conserved over many taxa and triggered by a plethora of stressors. Despite the overall response being fairly similar in both populations, there is a definite excess of genes with a strong cold-induced fold-change in Africa. This is consistent with a detrimental deregulation or an overshooting stress response. Thus, the canalization of European gene expression might be responsible for the increased cold tolerance of European flies.
Project description:Metabolites of cold hardy versus cold susceptible flies were compared using N less than R-based metabolomics. We used 8 replicates per line (2 hardy lines, two susceptible lines), and sampled each line at three time points (before, during and after cold), giving rise to 96 samples total.