Project description:The predicted increase in frequency and duration of winter warming episodes (WWEs) at the higher northern latitudes is expected to negatively impact the forage production in this region. The formation of non-permeable ice cover due to WWEs could subject the plants to hypoxic or anoxic conditions leading to severe winter damages. Knowledge about molecular mechanisms underlaying various winter stress is crucial to develop cultivars with better winter survival under changing climatic conditions. In the current study, we aimed at identifying genes involved in ice encasement stress responses in a perennial forage grass timothy and study gene expression differentiation due to field survival using timothy cultivars from diverse genetic backgrounds. The LD50 (the number of days under ice that kill 50% of the plants) varied across cultivars and origin. The expression of many genes involved in hypoxia and freezing stress responses were highly upregulated under ice encasement conditions. Functional analysis of DEGs revealed that the upregulated genes were linked to glycolysis, pyruvate metabolism, carbon metabolism, biosynthesis of amino acids while downregulated genes were related to photosynthesis, phenylpropanoid biosynthesis and flavonoid biosynthesis pathways. The results from a current study indicate a substantial overlap of ice encasement stress responses with those of hypoxic and freezing stresses. In addition, the potential strategies leading to higher ice encasement tolerance of timothy are outlined. Furthermore, differences in gene expression between field survivors and original material and the differences between ice encasement responses of northern adapted cultivar and southern adapted cultivar are briefly discussed.
Project description:Understanding the biogeographical patterns and underlying drivers of microbial functional diversity is essential for anticipating climate change impacts on ecosystem functioning worldwide. However, this matter remains scarcely addressed in freshwater ecosystems. Using the high-throughput gene array GeoChip 4.0, we show that functional gene alpha diversity and compositon differ across mountains, alpha diversity declines towards high elevations and compositional turnover increases with larger elevational distances. Both continental- and mountain-scale patterns were primarily driven by climatic variables.
Project description:Reduced parasitic infection rates in the developed world are suspected to underlie the rising prevalence of autoimmune disorders. However, the long-term evolutionary consequences of decreased parasite exposure on an immune system are not well understood. We used the Mexican tetra Astyanax mexicanus to understand how loss of parasite diversity influences the evolutionary trajectory of the vertebrate immune system, by comparing river with cave morphotypes. Here, we present field data affirming a strong reduction in parasite diversity in the cave ecosystem, and show that cavefish immune cells display a more sensitive pro-inflammatory response towards bacterial endotoxins. Surprisingly, other innate cellular immune responses, such as phagocytosis, are drastically decreased in cavefish. Using two independent single-cell approaches, we identified a shift in the overall immune cell composition in cavefish as the underlying cellular mechanism, indicating strong differences in the immune investment strategy. While surface fish invest evenly into the innate and adaptive immune systems, cavefish shifted immune investment to the adaptive immune system, and here, mainly towards specific T-cell populations that promote homeostasis. Additionally, inflammatory responses and immunopathological phenotypes in visceral adipose tissue are drastically reduced in cavefish. Our data indicate that long-term adaptation to low parasite diversity coincides with a more sensitive immune system in cavefish, which is accompanied by a reduction in the immune cells that play a role in mediating the pro-inflammatory response.