Czechia

Crucian carp (Carassius carassius) overwinter in ice-covered lakes and can survive anoxia for several months at low temperatures. The physiological adaptations allowing this survival are well understood at the whole-organism level, but we know less about the molecular machinery coordinating this adaptation to anoxia and reoxygenation and the possible involvement of epigenetic mechanisms. Due to the profound impact of DNA methylation on regulating gene expression, by directly influencing the accessibility of transcription factors and other regulatory proteins to the DNA, it acts as a switch mechanism and makes investigating it particularly interesting. Past RNA sequencing experiments to analyze the whole brain transcriptome have revealed that many genes are expressed differently in response to anoxia. We suspect that some of these changes in gene transcription during anoxia may be influenced by DNA methylation. Utilizing the next-generation Whole Genome Bisulfite Sequencing (WGBS) method combined with RNA sequencing, we investigated the altered gene activity-environment interaction, providing comprehensive, high-resolution, and quantitative methylation data. Our goal was to determine if genes that are differentially regulated during anoxic conditions are under epigenetic regulation by identifying a correlation between the DNA methylation loci on cytosines and differential RNA expression on the transcriptional level during and after anoxia exposure in the brain. The obtained data elucidates the role of DNA methylation in regulating the response to anoxia and guides us toward uncovering potentially novel molecular players in anoxia tolerance.

SEB Conference Prague 2024

DNA methylation alterations during anoxia and re-oxygenation in crucian carp brain

dna-methylation

anoxia tolerance

crucian carp

technical paper

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Until recently, the role of mitochondria in migration physiology and energetics has been mostly unstudied. The migratory phenotype consists of whole-organism to subcellular adaptations although a paucity of information exists on how organelles within the cell may play a critical role. Our research has focused on two-study comparisons of closely related migrants and non-migrants, in the family Mimidae and genus Zonotrichia. Here, we discuss our mitochondrial respiratory performance results between our study groups by measuring mitochondrial respiration using High-resolution respirometry. Additionally, we discuss other important variables and measurements that were collected that allow us to examine oxygen carrying capacity, fuel usage, and whole-organism performance. Our initial study on migratory and non-migratory, White-crowned Sparrows (Zonotrichia leucophyrs), demonstrated evidence of seasonal upregulation of mitochondrial performance related to migration. However, our Mimidae results did not. We discuss potential explanations for these patterns and how we are currently working to understand the mechanisms underlying our results. Lastly, we discuss our current work on expanding to other Zonotrichia groups to control for relatedness in our study.

Measuring mitochondrial respiratory performance in closely related migrant and non-migrant avian species

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 Does rapid adaptation to ocean warming and acidification leave behind a cellular metabolomic and lipidomic signature in a marine copepod? 

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Gasping for oxygen: The  cross-generational plasticity of  metabolism in Gasterosteus aculeatus exposed to fluctuating hypoxia

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Metabolic traits, chemotaxis, and environmental interactions of hydrothermal vent crab Xenograpsus testudinatus

While the compliant skin of dolphin has long been believed to play a crucial role in reducing skin friction drag owing to its flexibility and sensitivity, most conventional studies have been focused on the static skin microstructure and the hydrodynamic pressured-excited passive deformation, which could not provide a convinced solution to the mystery of Gray’s paradox. In this study, inspired by microvibrations measured on dolphin skin, we hypothesize that a dynamically undulating skin surface actuated by the microvibrations enables effectively altering the turbulent boundary layer adjacent to the skin, resulting in decreasing the velocity fluctuations, thus in reducing skin-friction drag. We constructed an idealized model of open channel with a portion of the bottom wall undergoing the microvibrations and carried out a series of numerical simulations to investigate the characteristics of the boundary layer flow in terms of traveling and standing waves. We found that the microvibrations-excited skin/wall surface can create a reversed flow against or enhance the streamwise flow in the viscous sublayer of the boundary layer, substantially leading to a negative friction drag or a negative total drag, hence greatly reducing or even eliminating the drag to generate a thrust. The results reveal that a novel drag reduction mechanism can be achieved by means of the dolphin-inspired microvibrations, which thus may provide a highly plausible explanation for the long-standing mystery of the excellent hydrodynamic performance in dolphin swimming.

Can compliant skin vibration provide a novel drag reduction strategy in dolphin swimming?

Understanding predator-prey interactions is crucial in ecological research, with timing and kinematics of escape responses greatly affecting animal survival to predator attacks. However, little is known about the escape responses of elasmobranchs, or chondrichthyans. In this study, we investigated the escape responses in the spotted ratfish (Hydrolagus colliei), a smaller chondrichthyan predator found in the Puget Sound, to compare its ability to perform fast-start escape behaviour against other chondrichthyan species that inhabit the same region.  Previous work has found that adult ratfish possess Mauthner cells (M-cells), a key neural element associated with fast reactions in the escape responses of teleost fish and larval amphibians, though not known to be present in other adult chondrichthyans. Escape responses were elicited using mechanical stimuli for nine individuals, and videos were analysed to quantify response latencies, and turning angles and rates. Results indicated that ratfish do perform fast-start escape responses, with variations in response characteristics across individuals. The ratfish had a shorter minimum latency (36ms) when compared to the spiny dogfish (Squalus suckleyi) (66.7ms), an elasmobranch found in the Puget Sound that does not have M-cells. These findings contribute to our understanding of predator-prey dynamics in chondrichthyan species.

Escape response timing and kinematics in a deep-water chondrichthyan, the spotted ratfish, Hydrolagus colliei

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Interactive effects of density and elevated temperature on foraging efficiency of aquatic predator

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Decolonising the curriculum - a case study from Tropical Ecology

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DNA methylation alterations during anoxia and re-oxygenation in crucian carp brain

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DNA methylation alterations during anoxia and re-oxygenation in crucian carp brain

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Measuring mitochondrial respiratory performance in closely related migrant and non-migrant avian species

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