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:The ability to cope with infection by a parasite is one of the major challenges for any host species and is a major driver of evolution. Parasite pressure differs between habitats. It is thought to be higher in tropical regions compared to temporal ones. We infected Drosophila melanogaster from two tropical (Malaysia and Zimbabwe) and two temperate populations (the Netherlands and North Carolina) with the generalist entomopathogenic fungus Beauveria bassiana to examine if adaptation to local parasite pressures led to differences in resistance. Contrary to previous findings we observed increased survival in temperate populations. This, however, is not due to increased resistance to infection per se, but rather the consequence of a higher general vigor of the temperate populations. We also assessed transcriptional response to infection within these flies eight and 24 hours after infection. Only few genes were induced at the earlier time point, most of which are involved in detoxification. In contrast, we identified more than 4,000 genes that changed their expression state after 24 hours. This response was generally conserved over all populations with only few genes being uniquely regulated in the temperate populations. We furthermore found that the American population was transcriptionally highly diverged from all other populations concerning basal levels of gene expression. This was particularly true for stress and immune response genes, which might be the genetic basis for their elevated vigor. mRNA profiles of whole Drosophila melanogaster adult males from an African, American, Asian and European population after infection with Beauveria bassiana. Samples include uninfected controls, 8h after infection and 24h after infection. 3 biological replicates each (2 in the case of American controls).
Project description:The ability to cope with infection by a parasite is one of the major challenges for any host species and is a major driver of evolution. Parasite pressure differs between habitats. It is thought to be higher in tropical regions compared to temporal ones. We infected Drosophila melanogaster from two tropical (Malaysia and Zimbabwe) and two temperate populations (the Netherlands and North Carolina) with the generalist entomopathogenic fungus Beauveria bassiana to examine if adaptation to local parasite pressures led to differences in resistance. Contrary to previous findings we observed increased survival in temperate populations. This, however, is not due to increased resistance to infection per se, but rather the consequence of a higher general vigor of the temperate populations. We also assessed transcriptional response to infection within these flies eight and 24 hours after infection. Only few genes were induced at the earlier time point, most of which are involved in detoxification. In contrast, we identified more than 4,000 genes that changed their expression state after 24 hours. This response was generally conserved over all populations with only few genes being uniquely regulated in the temperate populations. We furthermore found that the American population was transcriptionally highly diverged from all other populations concerning basal levels of gene expression. This was particularly true for stress and immune response genes, which might be the genetic basis for their elevated vigor.
Project description:Different populations of the same species survive different environments through local adaptation. Temperature is one of the most important driving forces that could result in local adaptation. Here, we studied the influence of extreme low temperature on the survival of two genetically and geographically distinct populations of the free-living Caenorhabditis briggsae. We found that Caenorhabditis briggsae strains of temperate origin had a cold resistant phenotype, while those originating from a tropical climate had reduced survival after cold treatment. Using this phenotypic difference between geographically diverse populations as a model for how species adapt to their local environment, we then analyzed the transcriptional profiles of two Caenorhabditis briggsae strains of tropical and temperate origin to find genes that are involved in survival after extreme cold. In summary, the response to the extreme low temperature that clearly distinguishes the temperate and tropical Caenorhabditis briggsae strains could serve as an excellent example for studying local adaption of species that show genetic separation associated with their geographical distribution.
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:Transcriptional profiling of 3 day old virgin male and female adults comparing control male Drosophila melanogaster (MDM) versus male D sechellia (MDS) and comparing control female Drosophila melanogaster (FDM) versus female D sechellia (FDS). Goal was to determine why D sechellia is tolerant to octanoïc acid, the major toxic compound of Morinda citrifolia fruit
Project description:Thermal acclimation study on Drosophila melanogaster reared at 3 different temperatures (12, 25, and 31oC). The proteomic profiles of D. melanogaster under these different temperatures were analyzed and compared using label-free tandem mass spectrometry.