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SEB Conference Prague 2024

Mechanisms of climate warming impacts on fish

fish

performance

temperature

technical paper

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SEB’s Annual Conference is celebrated for creating the perfect composition of research, new discoveries and collaborative connections. Be creative and innovative by exchanging ideas and knowledge with masters of biology from all over the world.

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.

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

The ability of marine species to rapidly adapt to multiple environmental changes is considered to be a fundamental mechanism in enabling them to survive global changes. Therefore, considerable efforts have been undertaken to test the evolutionary potential of multiple species when exposed to global change stressors. However, they mostly focused on single stressors exposure. As stressors can interact in non-linear manners, it is essential to better understand the mechanisms and the molecular signature of this adaptation in a multistressor context. Whilst genetic advances have greatly contributed to pinpointing some of the genetic mechanisms involved, a functional disconnect between genes and fitness remains: little is known about the actual changes occurring at the cellular level outside the nucleus following rapid adaptation. Therefore, building on the previous multigenerational selection experiment that looked at the fitness-related traits and genomic responses to ocean warming (OW) and ocean acidification (OA) in the marine copepod Acartia tonsa, we compared the metabolomics and lipidomics profiles of the F>100 lineages following their respective adaptation to OW and OA in isolation and in combination (OWA). Four pools of 200 individuals per lineage were flash frozen and metabolites and lipids were extracted and injected into a high-performance LC-MS/MS to obtain the concentration of 65 target metabolites involved in the energy pathways and whole lipidome profiles. Capacity and limitation for multiomics rewiring of A. tonsa are discussed within an adaptive context and in light of fitness-related life-history trait responses and genomic evidence.

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

As climate change accelerates, increasing air temperature average and variability pose substantial thermal challenges to animals. While plasticity in thermoregulatory traits could potentially attenuate this impact, whether thermal acclimatisation can occur quickly enough to track weather variability in hot climates is unknown in any endotherm, and sex differences have never been tested. We investigated acclimatisation responsiveness of male and female wild zebra finches to short-term (<2 weeks) summer temperature fluctuations in the Australian desert. Hotter weather before respirometry trials triggered a typical acclimatisation response. However, acclimatisation occurred remarkably rapidly: metabolic rate responded within just one day, while body temperature (Tb) and evaporative cooling capacity (EHL/MHP) were best predicted by weather on the trial day; whereas evaporative water loss responded more slowly (1 week). Nonetheless, rapid acclimatisation only occurred in males; and females had higher Tb and lower evaporative cooling capacity than males, potentially increasing hyperthermia risk. Furthermore, acclimatisation did not translate into greater acute heat tolerance (i.e. ability to tolerate chamber temperature =46°C). Our results therefore reveal surprisingly rapid acclimatisation, and even anticipatory adjustments to heat. However, with no changes in acute heat tolerance, nor in females, phenotypic flexibility may provide only limited buffering against the detrimental impact of heatwaves.

Thermal acclimatisation to heatwaves is rapid but sex-specific in wild zebra finches

The vent crab (Xenograpsus testudinatus), a dominant species in shallow water hydrothermal vents of Kueishan Island (Taiwan) and the Northwest Pacific fire ring, exhibits no significant genetic differentiation among populations. The underlying physiological traits and behavioral adaptations facilitating its survival in these environments are yet to be elucidated. This study collected X. testudinatus from two physicochemically contrasting sites: Kueishan Island and Shōwa Iōjima (Japan), the latter characterized by higher CO2 levels but lacking sulfides. Hemolymph analysis revealed comparable glucose levels between populations, but higher lactate in Shōwa Iōjima crabs, suggesting elevated CO2 contributes to anaerobic metabolism. In Kueishan Island, hemolymphic lactate positively correlated with sulfide presence and negatively with alkalinity, indicating a significant association between sulfide concentrations, alkaline components, and the regulation of anaerobic metabolic processes in the organism. Re-acclimatization experiments demonstrated a rapid lactate increase upon sulfide reintroduction, suggesting the importance of anaerobic respiration in adaptation. Moreover, vent crabs exhibited no positive sulfide chemotaxis, with Kueishan Island crabs displaying negative chemotaxis, potentially avoiding highly toxic areas. This study reveals diverse metabolic traits and behavioral responses employed by X. testudinatus to thrive in distinct hydrothermal habitats, underscoring the importance of phenotypic plasticity in their success.

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?

Climate change is causing rapid warming of Arctic regions threatening the ecosystem and their species such as the polar cod (Boreogadus saida). Polar cod is considered the most abundant forage fish species linking lower and higher trophic levels in the Arctic food web. In particular, the thermal tolerance of sensitive life stages, such as reproducing adults, is important for an assessment of biodiversity changes in the context of global warming. Here, a non-invasive experimental approach using magnetic resonance imaging (MRI) is presented to investigate the physiological performance of reproducing male, female and non-reproducing polar cod during acute warming. Inside the MRI scanner, 0°C pre-acclimated polar cod were exposed to a temperature ramp from 0°C to 8.5°C at a rate of 1.5 °C every two hours. A set of physiological performance parameters of the cardio-vascular system and energy status were continuously determined during the temperature ramp. In particular, flow-weighted MRI techniques were used to quantify blood flow in the head and in the abdomen, respectively, and the ventilation rate was assessed using CINE MRI. The energy status was determined by in vivo 31P-NMR spectroscopy. A preliminary data analysis showed a similar blood flow at the control temperature of 0°C for all three animal groups, whereas blood flow increased remarkably in the head of reproducing males during warming, which was more pronounced in comparison to non-reproducing individuals. These initial results could indicate a higher energy requirement of the reproducing males, leading to a higher sensitivity to future warming conditions.

Physiological response to acute warming of reproducing male and female polar cod (Boreogadus saida) using MRI

Predator-prey relationships are an important factor shaping ecological communities. Functional response (FR) describes the relationship between the food resource density and amount of food consumed by a single predator and is commonly used to study the role of predator-prey interactions in population dynamics. Elevated temperature related to global change is likely to modify consumer-resource interactions. Another important factor is predator density, as hunting individuals can be positively or negatively influenced by nearby conspecifics. Higher energy expenditure in elevated temperature requires greater foraging activity (enhancing foraging efficiency), which in turn may increase the competitive pressure between multiple predators and lead to predator interference (reducing foraging efficiency). This underlies the need to include predator density as a factor affecting foraging efficiency when studying effects of rising temperatures. Here, we performed a laboratory experiment using three densities of a fish predator (pumpkinseed, Lepomis gibbosus) (1, 2 and 4 specimens), two temperatures (25 and 28 oC) and 6 prey densities. Using FR approach, we showed the effect of temperature on foraging efficiency of single and 2 predators, but not on foraging of a group of 4 predators. Moreover, increased conspecific presence strongly reduced predator efficiency at a lower temperature, whereas, at a higher temperature, conspecific effect was totally absent (2 individuals) or lower (4 individuals). Our study indicates that predator density is an important factor that should be considered in experiments on the effects of environmental change on foraging efficiency. This research was supported by National Science Centre, Poland (Grant No. 2020/39/D/NZ8/01226)

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

Diverse scientific teams do more productive and high-impact science. Here we present student and staff ethnicity and disability data from the UK Higher Education Statistics Authority (HESA) for subdisicplines within biology. We identify significant underrepresentation of Black, Asian and disabled staff at senior academic levels, and a disproportionate loss of ethnic minority and disabled talent in the academic pipeline. We explore reasons that might underpin this from curriculum design to lack of role models to discrimiation and exclusionary practice. We offer recommendations for action, providing practical suggestions for how our disciplines can become less exclusionary and more welcoming to all students.

Ethnic Diversity and Disability in UK Bioscience: Structural Biases and Recommendations for Action

Tropical rainforest research was long the preserve of rich white men and the resulting literature was the same. This early bias in tropical research and publication may still be reflected in reading lists and recommended sources in higher education. We report on a study analysing the authorship of papers in the final year undergraduate option “Tropical Ecology” in SBOHVM University of Glasgow. The methodology utilised was that proposed by Bird and Pitman (2019) identifying gender, geography, and ethnicity of the authors. Nearly 79% of authors were male; 93.8% of authors whose ethnicity was identified were from non-BAME backgrounds; 80% of the authors were affiliated to institutes or universities in the global north. These results were reported to staff on the course with two outputs so far: reconsideration of the reading list and replacement of sources where possible; tutorial and discussion sessions with students taking the course to address the issues.


Decolonising the curriculum - a case study from Tropical Ecology

Exploring barley mutant and germplasm collections for plant architecture genes and alleles
Presenting author: Laura Rossini, University of Milan, Department of Agricultural and Environmental Sciences (DiSAA), Via Celoria 2, 20133 Milan, Italy
Laura.rossini@unimi.it 
Plant architecture traits play a fundamental role in plant fitness and adaptation. Breeders leverage variation in architectural features to select crops with improved performance under changing environments and agricultural practices. As a Neolithic founder crop now cultivated for different end uses across a wide ecogeographical range from Boreal regions to Tibet and sub-desertic areas in Africa, barley exhibits striking adaptability and genetic diversity. Further expanding barley germplasm diversity and taking advantage of its diploid genome, extensive mutant collections have been obtained through large scale mutagenesis programmes, establishing barley as a model for genetics and genomics of the Triticeae tribe. Research in our group builds upon these resources to identify and characterize genes and alleles shaping plant architecture traits, such as branching, culm morphology, leaf size and angle. In this talk I will illustrate current progress through selected case studies.

Mechanisms of climate warming impacts on fish

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

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Mechanisms of climate warming impacts on fish

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

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