Czechia

There is global scientific and commercial interest in understanding the impacts of climate warming and heatwaves on the resilience of fish populations. While heat is thought to act at a fundamental level on biological reaction rates, protein structure and cell membrane fluidity, much has been made of the role of oxygen in governing these processes. The “gill-oxygen limitation” (GOL) hypothesis proposes that the growth of fish gills does not keep pace with the increase in metabolic requirements of the body as fish grow, resulting in a progressive mismatch between oxygen supply and demand that is exacerbated at high temperatures. We have empirically tested this hypothesis in thermally acclimated fish in recent years and found no supportive evidence; gills have the plasticity to grow proportionally with metabolism to ensure that oxygen supply and demand are matched as fish grow, even at elevated temperatures. We have, however, found some evidence for oxygen supply limitations across the gills during acute thermal exposures, exacerbated as fish increase in size. This talk will discuss the current state of knowledge on these topics with an aim to shed light on the mechanisms compromising fish resilience to acute heatwaves and chronic warming.

SEB Conference 2024

Potential for gill-oxygen limitation in acute but not chronic thermal tolerance

fishes

metabolism

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.

The Northern shrimp (Pandalus borealis) is an ecologically and socio-economically important species in the North Atlantic, yet several of its different populations are collapsing due in part to global change drivers. Here, we aimed to elucidate the molecular mechanisms underlying shrimp responses to combined ocean warming (OW) and acidification (OA). Specifically, we profiled the phospholipidome of the abdominal muscle of female shrimp from four origins in the Northwest Atlantic, subjected to an orthogonal design of temperature (2, 6, or 10 °C) and pH (pH 7.75 or 7.40) scenarios. A suite of multivariate analyses revealed a complex interplay between shrimp origin and exposure to combined OW and OA, with OW primarily driving the phospholipidomic response, particularly at 10 °C. Warming to 10 °C altered phospholipids related to membrane thickness and lateral diffusion, and upregulated sphingomyelins. Notably, OA caused subtler effects, dependent on shrimp origin. Specimens from the Gulf of St. Lawrence showed an interactive effect of OW and OA, whilst those from the coasts of Newfoundland and Nova Scotia were not impacted by OA. Our finding has direct implications for prioritising conservation efforts on shrimp populations featuring a higher sensitivity to multiple stressors. Overall, our findings highlight the power of comparative omics to reveal different levels of intraspecific plasticity in the molecular response of marine organisms to future oceanic conditions. Our results will be refined by integrating multiomics and physiological traits within a multilayer framework to gain a comprehensive understanding of the response to global change drivers.

Molecular Responses of the Northern shrimp facing combined Ocean Warming and Acidification across the Northwest Atlantic Reveal Intraspecific Plasticity

In recent years, an important decline of honey bee populations is observed, in part due to environmental variations caused by climate change. Particularly, increased temperatures during winter and spring bring forth new challenges, as the transition from winter to summer is crucial for the colony's survival. We have recently demonstrated that honey bee mitochondria undergo drastic changes between the winter and summer seasons, which is attributed to their different roles within the hive. Specifically, winter bees have lower CI-linked respiration but increased mtG3PDH- and CII-linked respiration. However we do not know whether and how this affects ATP and reactive oxygen species (ROS) production. Further, the regulation mechanisms behind this drastic change in phenotype is unknown. In this study, we investigated the seasonal differences in mitochondrial oxygen consumption, ATP production, and site-specific ROS production in honey bees (Apis mellifera). We also evaluated supercomplex assembly to determine if this could explain the changes observed in the mitochondrial parameters measured. Our results demonstrate that even though CI-linked respiration is diminished in winter bees, ATP production by CI is increased, suggesting that CI is more efficient in winter. Differences were also detected in terms of ROS production, with summer bees producing less ROS than all other season. In terms of supercomplex assembly, we are currently performing the analyses, which has never been done in honey bees, and will be included in this talk. We hypothesize that supercomplex assembly could shed light on the results described above, explaining the contrasting mitochondrial phenotypes observed between seasons.

Seasonal effect on metabolism and mitochondrial supercomplex assembly in honey bees (Apis mellifera)

The severity and frequency of marine heatwaves (MHWs) have increased dramatically across the globe, particularly in the last decade. In ectotherms like fishes, temperature directly influences oxygen transport, leading to changes in oxygen consumption (i.e., metabolic rates). The effects of temperature on metabolism have consequences for organismal function, including swimming performance. Performance is expected to decline as metabolic demands accumulate at temperatures beyond a fish’s optimum, though declines may be mitigated through various means, including plastic responses. Rapid changes in temperature, exemplified through MHWs, may outpace an individual’s acclimation capacity, leaving them more vulnerable to detrimental thermal effects.
We investigated how heatwave exposure (i.e., +2°C and +4°C above normal summer temperature) over a five-day period affects the metabolic rate and swimming performance of a common nearshore marine fish species, the shiner perch (Cymatogaster aggregata), on San Juan Island, Washington. Using a swim tunnel respirometer, we measured standard and maximum metabolic rate (SMR and MMR, respectively), as well as critical swimming speed (Ucrit) and optimal swimming speed (Uopt). SMR was highest with moderate heatwave exposure (+2°C), while MMR was highly variable within treatments and increased slightly at the highest treatment temperature (+4°C). Ucrit did not vary across temperatures, but Uopt did decline with increasing temperatures. These findings provide insight into how this species may respond to future projected marine heatwaves, and also highlight the need for further studies focusing on metabolic performance across a range of relevant temperatures and acclimation periods.


Effects of heatwave exposure on the metabolism and swimming performance of a nearshore marine fish, Cymatogaster aggregata

Lab-reared organisms allow researchers to understand aspects of our natural environment under controlled conditions contributing knowledge to policy development, risk assessment, and environmental systems. However, it is important to consider whether lab-reared organisms are actually representative models for their wild counterparts. To address this, our study compared the toxicity of ultraviolet filters (UVFs) between lab-reared and wild-caught Daphnia pulex to understand the effect of life-history on environmental exposures. 48-hour exposures of daphnids to avobenzone, oxybenzone, or octocrylene found minimal differences in both lethal and sublethal acute toxicity; however, several large deviations in chronic toxicity were observed over 21 day exposures. Wild daphnids exposed to 100 μg/L of octocrylene exhibited a 53% reduction in total reproduction compared to lab daphnids, as well as a 16% smaller core body size. In addition, differences in mortality were apparent between each population, as lab Daphnia experienced 30% higher mortality to 100 µg/L oxybenzone, while wild Daphnia experienced 30% higher mortality to 100 µg/L octocrylene. Overall, these results highlight a clear difference between the tolerance of lab-reared and wild organisms to UVFs, and that these differences are chemical specific. These results highlight the need for more environmentally relevant test methods for the use of model organisms across a multitude of fields, including physiology and toxicology. While the practicality and accessibility of lab-reared model organisms is an important tool, it is worth considering the use of their wild counterparts to provide a more accurate picture of these organismal functions in nature.

They're Sisters Not Twins: Understanding the differences in lab-reared & wild caught Daphnia pulex responses to ultraviolet filter exposure.

Productive marine coastal ecosystems such as coral reefs, seagrass meadows, kelp forests and mangroves are characterised by circadian fluctuations of oxygen controlled by temperature and the cycle of photosynthesis and respiration of the primary producers. Marine species living in such productive coastal habitats have therefore evolved in highly dynamic diel and seasonally fluctuating environments. Consequently, studies strictly based on rigorous laboratory conditions may not capture, or test, the real effect of environmental fluctuations on the thermal tolerance of marine species, which is directly linked with environmental oxygen availability. In this study we selected three areas, across a large latitudinal scale, with different levels of temperature and oxygen fluctuations and predictability. By incorporating lab experiments with ecologically relevant oxygen levels recorded from the field, we hypothesized that the degree of the diel environmental fluctuations in the coastal areas can explain the thermal response of marine species. To test this hypothesis, we measured the thermal tolerance of 17 marine ectotherm animal species from the three different locations, from tropical to warm and cold temperate environment. Our results showed that higher predictability of oxygen and temperature fluctuation increases the magnitude of species’ thermal tolerance compared to those in less predictable environments. We advocate that ecologically relevant environmental oxygen fluctuation needs to be considered when measuring and forecasting the response of marine animals to global warming and it provides a new background to assess aquatic communities’ thermal tolerance.

Accounting for ecologically relevant oxygen fluctuation explains thermal tolerance plasticity in marine species

Functional trade-offs impose important constraints on the biomechanics of musculo-skeletal systems. In songbirds, for example, a force-velocity trade-off has been described in singing, showing that hard-biting birds sing at lower syllable rates. However, we do not yet know whether and how this also affects their feeding kinematics. Many songbirds are granivorous, i.e., rely on seeds as their major food source. Thus, we analysed seed processing in two granivorous species, canaries (bite force ≈3 N) and Java finches (bite force ≈10 N), using X-ray Reconstruction of Moving Morphology (XROMM). We show that canaries move their beaks at a ≈23% higher angular velocity and at a ≈31% higher frequency compared to Java finches. Furthermore, canaries use a wider range of motion in both the upper and lower beak during seed processing. Last, we show that these differences in beak biomechanics are also associated with differences in seed processing strategies in the tested species: Java finches crack the seeds more easily than canaries, but they often crush the inner kernel and consequently drop parts of it. Canaries, however, are able to remove the shell without crushing the seed and swallow the kernel in whole. This suggests that a force-accuracy trade-off might be at play in the beak's fine motor control. Our results indicate that a combination of trade-offs (force-velocity, force-frequency, and force-accuracy) has an impact on the feeding biomechanics of granivorous songbirds and hence may play an important role in the adaptation to specific seed types.

Biting fast or biting hard? Comparative XROMM analysis reveals functional trade-offs in beak movements of feeding songbirds.

Formins are an evolutionarily old family of cytoskeletal regulators whose roles include microfilament capping, actin nucleation, and modulation of microtubule dynamics. Plant class I formins typically exhibit a unique domain organization, with most of them being transmembrane proteins with possible cell wall-binding motifs exposed to the extracytoplasmic space. Although such transmembrane formins are traditionally considered mainly as plasmalemma-localized proteins, they could also, at least temporarily, reside in endomembranes. Some of them decorate the plasmodesmata. We are currently developing techniques to use a photoswitchable fluorochrome for examining the effects of formin mutations on intercellular transport. Moreover, the main housekeeping Arabisopsis thaliana class I formin, AtFH1, relocates between the plasmalemma and several endomembrane compartments during cell division and differentiation in root tissues, with transient tonoplast localization at the transition/elongation zone border. However, it is unclear whether the tonoplast-localized AtFH1 performs any biologically relevant function or whether is merely briefly occurs at the tonoplast en route towards vacuolar degradation. We shall present observations suggesting that both possibilities are mutually compatible: while mutational loss of AtFH1 affects tonoplast organization, the formin also enters the vacuole lumen. Another Class I formin, AtFH5, also enters the vacuole via an autophagic pathway under certain conditions and contributes to specific stress resistance. We propose a model where class I formins may serve as “active cargoes” of membrane trafficking, i.e. membrane-embedded proteins that modulate the fate of membrane compartments they reside on.
This work has been supported by the Czech Science Foundation grant 22-33471S.


Plant Class I formins: from actin organizers to active cargoes of membrane trafficking

Plant formin proteins belong to a large family of eukaryotic cytoskeleton regulators. The role of formin in cellular processes and actin regulation has been studied in the Arabidopsis root. The plamsmodesmata localised formins has shown influence on the symplastic transport by affecting the callose and actin. An extensive comparison among mutants and effects of cytoskeletal drugs on symplastic transport have been performed using DRONPa technique. Formins also studied to affect the lateral root formation.

Characterizing the role of plant class I formins in symplastic transport

Developing an inclusive, diverse, and cutting-edge curriculum is high on the priority list for universities. However, to undertake this it requires time and energy, something that as educators we are often lacking - regardless of our drive. Working in partnership with students provides unique opportunities to enable content development. Through student-staff partnerships, students are often best placed to provide insights into their own learning, by having autonomy over content through ownership of novel ideas and approaches that are relevant to today’s needs. This partnership also provides a platform for students to build confidence in their abilities and the education system that they are a part of to provide a more inclusive environment. Staff on a learning and teaching track gain valuable opportunities for scholarship from these partnerships and it can also spread the time constraints.
As with any opportunity we need to balance the scales. It takes time to find students that are able to balance this extra workload with their studies and have the maturity to see beyond their own needs. After leading on student-staff partnerships, I am aware of the differing outcomes which can arise, and these are often down to the individual team, where resources are limited and tightly time-bound. When it works it provides an insightful curriculum. When it doesn’t then the shift of workflow falls to us. I will provide some insights into student-staff partnerships and highlight the benefits and areas to be wary of before jumping in. 


Student-Staff Partnerships the way forward for an inclusive curriculum-Some insights before jumping in

Autochthonous ecotypes are plant genetic resources characterized by high genetic variability, tolerance to environmental stress conditions, the presence of specialized metabolites (terpenoids, flavonoids, and alkaloids), and health-promoting compounds. However, autochthonous ecotypes are gravely threatened by extinction, mainly because of their replacement by commercial varieties. To preserve autochthonous ecotypes and their diversity, as well as to make them an ideal alternative for commercial varieties, it is very important to identify their unique characteristics. The present study aimed to provide a global view of the metabolite diversity of three autochthonous lentil ecotypes from different villages of the Molise region (Italy): Capracotta, CA; Rionero Sannitico, RS; and Agnone, A; and one ecotype from the Umbria region (Italy): Castelluccio di Norcia, CS. Untargeted metabolomics, performed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS), allowed the detection of 663 differentially accumulated metabolites (DAMs), which were assigned to 13 metabolic categories using MS libraries (e.g., the GNPS Public Spectral Library) and a molecular network approach. Major classes included flavonoids (90–13.6%), amino acids and derivatives (70–10.5%), and cinnamic acids (55–8.3%). According to the PCA and PLS-DA score plots, the metabolite compositions of autochthonous ecotypes differed significantly from each other. These results have been confirmed by heatmap, allowing the selection of ecotype-specific metabolic features. The enrichment analysis is in progress to assess the presence of enriched metabolic categories for each ecotype, and the antibacterial, antiproliferative, and antioxidative activity of lentil extracts was also evaluated according to the differential metabolic profiles characterizing each ecotype.

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Molecular Responses of the Northern shrimp facing combined Ocean Warming and Acidification across the Northwest Atlantic Reveal Intraspecific Plasticity

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