Project description:We have used long-term experimental selection over many generations to obtain Drosophila melanogaster strains that can live perpetually in extremely low, normally lethal O2 conditions (4-5% O2). These strains show a dramatic phenotypic divergence from control animals, including a decreased recovery time after anoxia, a higher rate of O2 consumption in hypoxic conditions, and a decrease in body mass due to both decreased cell proliferation and cell size. We used gene expression profiling to identify altered transcript levels in the adapted flies and we show that mutations in many of the corresponding genes confer the ability to survive under extremely low O2 conditions. Keywords: genetic bases of hypoxia adaptation
Project description:One of the critical substances that mammals highly regulate via the respiratory, cardiovascular and neurologic systems is O2. Both low and high O2 levels can induce major morbidities as well as mortality. Indeed, O2 has been often considered as both an elixir and a poison in humans. In current study, we have used an experimental selection approach to generate Drosophila strains that are tolerant to severe hyperoxic environment. Gene expression profiling is then applied to investigate the mechanisms underlying hyperoxia tolerance in the newly generated strains.
Project description:One of the critical substances that mammals highly regulate via the respiratory, cardiovascular and neurologic systems is O2. Both low and high O2 levels can induce major morbidities as well as mortality. Indeed, O2 has been often considered as both an elixir and a poison in humans. In current study, we have used an experimental selection approach to generate Drosophila strains that are tolerant to severe hyperoxic environment. Gene expression profiling is then applied to investigate the mechanisms underlying hyperoxia tolerance in the newly generated strains. 27 isogenic D. melanogaster Lines were pooled and following long-term selection over generations with increased oxygen level in the culture environment. The differences in gene expression were compared between adapted flies and generation matched naive controls by microarray.
Project description:Hypoxia-induced cell injury has been related to multiple pathological conditions. In order to render hypoxia-sensitive cells and tissues resistant to low O2 environment, in this current study, we used Drosophila melanogaster as a model to dissect the mechanisms underlying hypoxia-tolerance. A D. melanogaster strain that lives perpetually in an extremely low-oxygen environment (4% O2, an oxygen level that is equivalent to that over about 4,000 m above Mt. Everest) was generated through laboratory selection pressure using a continuing reduction of O2 over many generations. This phenotype is genetically stable since selected flies, after several generations in room air, survive at this low O2 level. Gene expression profiling showed striking differences between tolerant and naïve flies, in larvae and adults, both quantitatively and qualitatively. Up-regulated genes in the tolerant flies included signal transduction pathways (e.g., Notch and Toll/Imd pathways), but metabolic genes were remarkably down-regulated in the larvae. Furthermore, a different allelic frequency and enzymatic activity of the triose phosphate isomerase (TPI) was present in the tolerant versus naïve flies. The transcriptional suppressor, hairy, was up-regulated in the microarrays and its binding elements were present in the regulatory region of the specifically down-regulated metabolic genes but not others, and mutations in hairy significantly reduced hypoxia tolerance. We conclude that, the hypoxia-selected flies: (a) altered their gene expression and genetic code, and (b) coordinated their metabolic suppression, especially during development, with hairy acting as a metabolic switch, thus playing a crucial role in hypoxia-tolerance. Keywords: genetic bases of hypoxia adaptation
Project description:Hypoxia-induced cell injury has been related to multiple pathological conditions. In order to render hypoxia-sensitive cells and tissues resistant to low O2 environment, in this current study, we used Drosophila melanogaster as a model to dissect the mechanisms underlying hypoxia-tolerance. A D. melanogaster strain that lives perpetually in an extremely low-oxygen environment (4% O2, an oxygen level that is equivalent to that over about 4,000 m above Mt. Everest) was generated through laboratory selection pressure using a continuing reduction of O2 over many generations. This phenotype is genetically stable since selected flies, after several generations in room air, survive at this low O2 level. Gene expression profiling showed striking differences between tolerant and naïve flies, in larvae and adults, both quantitatively and qualitatively. Up-regulated genes in the tolerant flies included signal transduction pathways (e.g., Notch and Toll/Imd pathways), but metabolic genes were remarkably down-regulated in the larvae. Furthermore, a different allelic frequency and enzymatic activity of the triose phosphate isomerase (TPI) was present in the tolerant versus naïve flies. The transcriptional suppressor, hairy, was up-regulated in the microarrays and its binding elements were present in the regulatory region of the specifically down-regulated metabolic genes but not others, and mutations in hairy significantly reduced hypoxia tolerance. We conclude that, the hypoxia-selected flies: (a) altered their gene expression and genetic code, and (b) coordinated their metabolic suppression, especially during development, with hairy acting as a metabolic switch, thus playing a crucial role in hypoxia-tolerance. Keywords: genetic bases of hypoxia adaptation 27 isogenic D. melanogaster Lines were pooled and following long-term selection over generations with decreased oxygen level in the culture environment. The differences in gene expression were compared between adapted flies and generation matched naive controls by microarray. Pooled RNA samples from 3rd instar larvae of 27 parental lines were used as common reference.
Project description:Hypoxia plays a key pathogenic role in the outcome of many pathologic conditions. To elucidate how organisms successfully adapt to hypoxia, a population of Drosophila melanogaster was generated, through an iterative selection process, that is able to complete its lifecycle at 4% O2, a level lethal to the starting parental population. Transcriptomic analysis of flies adapted for >200 generations was performed to identify pathways and processes that contribute to the adapted phenotype, comparing gene expression of three developmental stages with generation-matched control flies. A third group was included, hypoxia-adapted flies reverted to 21% O2 for five generations, to address the relative contributions of genetics and hypoxic environment to the gene expression differences. We identified the largest number of expression differences in 0.5-3 hr post-eclosion adult flies that were hypoxia-adapted and maintained in 4% O2, and found evidence that changes in Wnt signaling contribute to hypoxia tolerance in flies.
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:Hypoxia plays a key pathogenic role in the outcome of many pathologic conditions. To elucidate how organisms successfully adapt to hypoxia, a population of Drosophila melanogaster was generated, through an iterative selection process, that is able to complete its lifecycle at 4% O2, a level lethal to the starting parental population. Transcriptomic analysis of flies adapted for >200 generations was performed to identify pathways and processes that contribute to the adapted phenotype, comparing gene expression of three developmental stages with generation-matched control flies. A third group was included, hypoxia-adapted flies reverted to 21% O2 for five generations, to address the relative contributions of genetics and hypoxic environment to the gene expression differences. We identified the largest number of expression differences in 0.5-3 hr post-eclosion adult flies that were hypoxia-adapted and maintained in 4% O2, and found evidence that changes in Wnt signaling contribute to hypoxia tolerance in flies. A population of flies able to complete their life cycle at 4% O2 was selected from a starting population of 27 isogenic D. melanogaster lines exposed to increasingly lower O2 levels over many generations. Transcriptomic analysis of adapted flies maintained at 4% O2 or reverted to room air for five generations, and of generation matched naive controls, was performed to better understand changes in gene expression in adapted flies and to investigate the relative contributions of genetics versus environment to these differences.