Czechia

Teleosts maintain body fluid ionic and acid-base homeostasis through energy-consuming ion transport mechanisms in the gills and other organs. Our serial studies identified a new gill cell type (GR cells) in zebrafish and tilapia, which are rich in glycogen and provide glucose or lactate/pyruvate to neighboring ionocytes. Different types of glucose and monocarboxylate transporters were found to facilitate energy deposition and supply between ionocytes and GR cells. On the other hand, ammonotelic fishes are suggested to rely on ammonia excretion to enhance net acid secretion because ammoniogenesis produces HCO3- to facilitate body fluid acid-base homeostasis. We recently extended our study to understand how ammoniagenesis occurs and is coordinated with ammonia excretion in fish gills. In medaka and other species, we have discovered an undiscovered ammonia-producing cell type that is rich in glutaminase (GLS cells) and located adjacent to the ammonia-excreting ionocytes (NHE cells) in the gills. The unique division of labor between GLS and NHE cells in the gills allows medaka to simultaneously upregulate GLS activity and ammonia excretion shortly after exposure to acidic environments. These findings provide fundamental information to enhance our mechanistic understanding of the energy metabolism underpinning gill ion transport functions and the related physiological adaptations of vertebrates during evolution.



SEB Conference 2024

Ion regulation and related energy metabolism in fish gills

energy metabolism

fish. osmoregulation

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SEB Conference 2025

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.

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The Giant Grouper (Epinephelus lanceolatus) is an important species in aquaculture industry of Taiwan. However, during the fry stage, susceptibility to nerve necrosis virus (NNV) poses a considerable challenge, impacting the industry substantially. Furthermore, as a species inhabiting tropical and subtropical regions, environmental temperature serves as a critical factor influencing grouper physiology, potentially modulating the expression of disease resistance genes. Previous research highlights the importance of interferon in the antiviral pathway, with protein kinase R downstream playing a crucial role in disease and stress resistance. This study aims to investigate the effects of hypothermal stress and NNV on giant grouper through PKR gene expression analysis. The results indicate that low temperatures elevate PKR expression in giant grouper larvae, consequently inhibiting NNV replication. Therefore, low temperatures may assist giant grouper larvae in avoiding NNV infection. This study further explored the effects of hypothermal stress and NNV on grouper protein kinase R expression, offering insights into disease resilience mechanisms.

Effects of Hypothermic Stress on Giant Grouper (Epinephelus lanceolatus) PKR Gene Expression and Antiviral Response Against NNV

The stress history of an individual is predicted to impact how they handle sudden increases in environmental temperature. However, our understanding of how prior exposure to commonplace stressors, like salinity and crowding, affects ectotherm heat tolerance is lacking. We hypothesised that brief exposure to mild stress would heighten tolerance to subsequent heat stress, indicative of a cross-tolerance interaction, whereas exposure to severe stress would reduce heat tolerance, reflecting a cross-susceptibility interaction. To test this hypothesis, we assessed how three acute stressors (salinity shock, air exposure, and crowding), commonly experienced by fish, affected the heat tolerance (measured as critical thermal maximum, CTmax) of juvenile Chinook salmon (Oncorhynchus tshawytscha). Fish were exposed to one of the three stressors and left for 24 h of recovery prior to measuring CTmax. This talk will detail how the stress history (salinity shock, air exposure, or crowding) impacts the capacity to withstand a subsequent heat shock. We highlight evidence of cross-tolerance and cross-susceptibility among commonplace stressors, and detail dose-dependent effects.

Stress history affects heat tolerance in an aquatic ectotherm (Chinook salmon,Oncorhynchus tshawytscha)

Introduction: Piloerection, the phenomenon of hair standing on end, is commonly viewed as an emotional response in humans1, a perspective that potentially overlooks its broader biological significance. Unlike in other mammals where piloerection has clear functional roles, the human response has been labelled vestigial2 due to our lesser hairiness. This study challenges the notion, proposing piloerection as a complex response to environmental stimuli.
Aim and Hypothesis: We aimed to explore whether tactile, thermal, and audio-visual stimuli could trigger human piloerection, hypothesizing it as a multifunctional response to environmental changes rather than a mere emotional or vestigial reaction. We further hypothesized that piloerection influences skin temperature and is more predictably triggered by objective stimuli than by subjective emotional states or perceived coldness.

Experimental Design: We exposed participants to a variety of tactile, thermal, and audio-visual stimuli to induce piloerection. Through observing 1198 piloerection events in eight participants, we examined cardiovascular (ECG, cardiac impedance, respiration) and skin and core temperature responses to diverse stimuli, alongside participants' self-reported emotions and subjective feelings of coldness vs warmness. 

Results: Results indicated that audio-visual stimuli inducing a stronger sympathetic response and tactile stimuli inducing a parasympathetic response. Challenging its classification as vestigial, piloerection episodes were associated with changes in skin temperature (see Figure 1) and this change was stronger for more intense episodes of piloerection (B = -.98, p < .001). Finally, environmental conditions (e.g. ambient temperature: sr2 = .53, p < .001) were more reliable predictors of piloerection than participants' subjective reports (e.g. self-reported coldness: sr2 = .02, p = .107) , challenging its treatment as a purely affective response in humans.

Conclusion: This research fundamentally challenges the prevailing understanding of piloerection in humans, presenting it not as an emotional artifact but as a nuanced physiological response to a variety of environmental stimuli. By demonstrating that human piloerection mirrors its function in other species, this study highlights the evolutionary continuity of physiological responses across species. The implications of these findings suggest a need to reconsider the role of piloerection in human physiology and psychology, from a marker of emotional states3 to a broader indicator of sensory and environmental engagement.


Diverse stimuli induce piloerection and yield varied autonomic responses in humans

Wildfire prevalence has increased drastically around the world, exacerbated by climate change, resulting in devastation to ecosystems and the organisms therewithin. Australian bushfires are of particular concern given Australia’s extensive biodiversity and numerous endemic species. While terrestrial impacts are often the primary concern for fires, the aquatic environment is also at risk. Ash from fires can directly descend into aquatic environments or be introduced as runoff, and which can release heavy metals and contaminants such as polyaromatic hydrocarbons. The physiological effects of bushfire ash on aquatic animals are not well understood, nor is their subsequent coping and recovery ability. Two native Australian freshwater species, the long-armed shrimp (Macrobrachium australiense) and the blue yabby (Cherax destructor), were selected to examine their physiological responses following exposure to Australian bushfire ash. We found that the shrimp were significantly more sensitive to ash than the crayfish. Metabolic oxygen consumption was measured, and the enzymatic activity of cytochrome c oxidase and lactate dehydrogenase were assessed in three tissue types (gills, hepatopancreas and muscle). Thus, insight is gained into the species method of cellular respiration. The sensitivity and effects of ash exposure are important to adequately evaluate the effects of bushfires. The ability for animals to contend with ash exposure will allow for identification of critical areas where monitoring and conservation efforts should be made following bushfires.

Swimming in ash: Comparing physiological responses of two freshwater crustaceans to Australian bushfire ash

Since the introduction of global shipping lanes, the European green crab (Carcinus maenas) has become a highly successful invasive species, colonizing every continent except for Antarctica. First sighted in San Francisco Bay, CA in 1989, the invasive green crab population quickly spread to Vancouver Island, BC in less than 10 years. Upon introduction, a comparatively high tolerance to fluctuations in temperature and salinity allows C. maenas to outcompete native crustacean species for habitats and resources. Given that nearly 30% of the Canadian Pacific Coastline is considered marine protected area, harbouring critical native species and habitats, understating the factors influencing the survival and spread of C. maenas may be vital in mitigating their harm. Additionally, the estuarine coastline of Vancouver Island offers a highly variable environment, with salinity ranging anywhere from full strength sea water, to dilute freshwater inputs. Here, using a multi-stressor approach, we evaluated the upper thermal tolerance of the green crab in combination with variable salinity. In particular, we investigated how changes in environmental salinity influenced the critical thermal maximum (CTmax) of the green crab. First, six male crabs were assigned to each of the following treatment groups, 100% salinity, 50% salinity, 20% salinity, and acute 0% salinity, then CTmax was assessed. Interestingly, no significant differences in CTmax were found in response to changes in environmental salinity, exhibiting a CTmax of approximately 37.6 ± 0.3 °C. In response to changes in salinity, heart rate, temperature induced maximum metabolic rate, resting metabolic, and freshwater LT50 are also evaluated at various temperatures. This research offers valuable information regarding C. maenas’ tolerance to environmental stress related to variable estuarine environments, which may play a vital role in predicting and thus mitigating their invasive success on the Canadian Pacific Coastline.

The influence of variable salinity on invasive green crab (C. maenas) survival in Canadian Pacific estuaries.

Experimental variation is a multi-faceted phenomenon leading to both intra-experimental and inter-experimental incongruencies. Such variation often manifests in nonreproducibility of experiments which is rightfully regarded as an issue in experimental sciences. Nonreproducibility has been attributed to inadequate reporting of methods, sloppiness/honest error, and even misconduct. We hypothesized that, within the field of animal physiology, the most parsimonious explanation for nonreproducibility is inadequate reporting of key methodological details. We analyzed 84 research articles published in five primarily organismal animal physiology journals and assessed compliance for 34 reporting variables referring to biology, experimentation, and data collection/analysis. Our study shows that about one third of necessary information on the methodology is missing. We thus assume that at least within the life sciences, underreporting of key variables can lead to a lack of reproducibility that is independent of the rigor of the study, but rather reflects the lack of rigor of the journal article preparation as well as peer review and publishing.

Addressing Nonreproducibility: Examining Methodological Reporting in Animal Physiology Studies

Plants are sessile organisms adapting constantly to environmental fluctuations through spatial and temporal transcriptional responses. We used the latest generation of MS2 RNA labelling system combined with microfluidics to monitor impact of modification of phosphate supply by live transcription imaging. MS2/MCT system is based on a fusion between GFP and the coat protein of bacteriophage MS2 (MCP-GFP), which recognizes a specific RNA stem-loop inserted in multiple copies into a reporter RNA. This enabled quantitative measurements of the transcriptional activity of single loci in living Arabidopsis plants, providing direct visualization of transcriptional regulation within entire organs. Using phosphate responsive genes as model, we found that active genes displayed high transcription initiation rates and frequently clustered together in endo-replicated cells. We also observed large differences between alleles of single cells and in agreement, intrinsic noise was larger than extrinsic variations. Moreover, we established that the transcriptional repression triggered in roots by phosphate, a crucial macronutrient limiting plant development, occurred with unexpected fast kinetics in the range of minutes, and with striking heterogeneity between neighboring cells. Access to single cells RNA polymerase II dynamics within live plants will benefit the study of numerous signaling processes.

RNA live imaging: interest for plant biology

Temperature is a key determinant of plant distribution and phenology. Warmer temperatures due to climate change have already altered the flowering times of wild plants, and crop yields decline significantly with additional temperature stress. Despite the importance of temperature on plant growth and development, little is understood of the mechanisms of temperature sensing in plants. We have identified thermosensory nodes that can account for key warm temperature responses for both stress and developmental pathways. We have found that protein phase change appears to play a role in several temperature response pathways, and I will describe some of these in Arabidopsis thaliana.

Temperature sensing in plants

Rice is one of the major global food crops. Although the overall yield of rice has been increasing, the growing population and adverse climatic changes pose huge challenges for their sustained production in the future. Therefore, systematic approaches are highly required to explore their effects on cereal crops’ phenotypic and cellular responses. It could be achieved by combining the available multiple high throughput data such as genomics, metabolomics, proteomics and transcriptomics, thereby analyzing the possible biochemical adaptations to several abiotic and biotic stresses, and subsequently improving the crop yield. Concurrently, the advent of constraint-based metabolic reconstruction and analysis paves way to characterize cellular physiology under various stresses via the mathematical network models. We have employed similar systems biology approach, and initially developed a core mathematical model of rice to characterize cellular behaviour and metabolic states under various abiotic stress conditions. The core model was then further expanded to reconstruct a fully compartmentalized genome scale metabolic model. Subsequently, transcriptomics and metabolomics data were systematically integrated with the model to identify the potential candidate regulatory genes as new breeding targets for improving rice production. In addition, we have also reconstructed a genome-scale metabolic model of Xanthomonas oryzae pathovar oryzae (Xoo) that causes leaf blight in rice leading to severe yield losses. In future, in silico model-guided framework can be further extended by including comprehensive genome-scale model of rice and its leaf microbiome for characterizing their interactions. This may allow us to systematically devise new strategies to control leaf blight in rice.

Plant systems biology: application to rice for understanding cellular phenotype to guiding crop improvement under abiotic and biotic stress conditions

Genome specific association study (GSAS) for exploration of intravarietal variability in hemp (Cannabis sativa)

Trubanová Nina (1); Isobe Sachiko (2); Shirasawa, Kenta (2); Watanabe, Akiko (2); Melzer, Rainer (1, 3), Schilling, Susanne (1, 3)

1 School of Biology and Environmental Science, University College Dublin, Science Centre West, Belfield, Dublin 4, Republic of Ireland; 2 Laboratory of Plant Genetics and Genomics, Department of Frontier Research and Development, Kazusa DNA Research Institute; 3 UCD Earth Institute, University College Dublin

Hemp (Cannabis sativa L.) stands out as a versatile crop with substantial economic potential. However, its intravarietal phenotypic and genetic variability remain inadequately elucidated. In the context of advancing crop improvement efforts, our research addresses this gap by employing an innovative genome-specific association study (GSAS) framework.
The GSAS methodology involves the streamlined generation of a single phenotyped population, the selection of alleles heterozygous in the parent plant, and the application of a model conducive to the polygenic association of studied traits. Through extensive exploration of plant growth, development, and reproductive patterns, along with genetic variability analysis of a population derived from a single plant, we identified statistically significant single nucleotide variants and haplotypes associated with studied traits.
Here presented study highlights the potential of the GSAS approach for utilising genomics and phenomics to significantly advance our understanding of the genetic determination of intravarietal phenotypic variability in hemp and other highly heterozygous crops. The findings from prospective GSAS studies hold promise for marker-assisted breeding, enabling the development of new cultivars with enhanced uniformity and improved performance in traits relevant to various applications, ranging from pharmaceuticals to the manufacturing of materials with superb properties, adaptable to various climates.

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Effects of Hypothermic Stress on Giant Grouper (Epinephelus lanceolatus) PKR Gene Expression and Antiviral Response Against NNV

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Next from SEB Conference 2024

Effects of Hypothermic Stress on Giant Grouper (Epinephelus lanceolatus) PKR Gene Expression and Antiviral Response Against NNV

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How zebrafish handle their nitrogenous waste: Determining the skin-to-gill transition of rhesus glycoproteins

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