Biology subjects

Jungwirth, A.

Publications and source records attributed to Jungwirth, A..

3 recordsLinked to original sources

bioRxiv2024

Multiple within species comparisons show Tanganyikan cichlid fish have larger brains in less structurally complex habitats

Many studies have found a link between higher habitat structural complexity and increased relative brain size in vertebrates. Here we explore this relationship in a multi-species comparison, comparing ten species of wild cichlids that differ in their social and territorial behaviour, but which occur across four ecologically similar but structurally diverse rocky habitats. This design allows us to perform repeated intra-specific comparisons, avoiding confounds associated with comparisons across species boundaries. We sampled 147 fish, analysing brain size and architecture while controlling for body mass and species-specific variability and compared this with habitat complexity, quantified using underwater video and three-dimensional reconstructions. Our results challenge the Clever Foraging Hypothesis (CFH), which posits that greater habitat complexity correlates with larger brain sizes. Contrary to CFH, fish from the least complex habitat had significantly larger brains. Additionally, brain architecture analysis indicated a significant enlargement of the cerebellum in fish from less complex habitats, whereas the hypothalamus showed a non-significant negative trend. Taken together, these results indicate that lower habitat complexity may impose higher cognitive demands on spatial memory and navigation due to limited refuges and increased predation risk. This study highlights the need to reconsider the assumed linear positive relationship between environmental complexity and brain development, suggesting that simpler environments might also impose significant cognitive and ecological challenges that drive brain evolution. Our findings underscore the importance of considering intra-species variability and the specific ecological and cognitive demands of different habitats in studies of brain evolution.

evolutionary biology↗

bioRxiv2023

Catalytic antibodies in arrhythmogenic cardiomyopathy patients cleave desmoglein 2 and N-cadherin and impair cardiomyocyte cohesion

AimsArrhythmogenic cardiomyopathy (AC) is a severe heart disease predisposing to ventricular arrhythmias and sudden cardiac death caused by mutations affecting intercalated disc (ICD) proteins and aggravated by physical exercise. Recently, autoantibodies targeting ICD proteins, including the desmosomal cadherin desmoglein 2 (DSG2), were reported in AC patients and were considered relevant for disease development and progression, particularly in patients without underlying pathogenic mutations. However, it is unclear at present whether these autoantibodies are pathogenic and by which mechanisms show specificity for DSG2 and thus can be used as a diagnostic tool. Methods and ResultsIgG fractions were purified from 15 AC patients and 4 healthy controls. Immunostainings dissociation assays, atomic force microscopy (AFM), western blot analysis and Triton-X-100 assays were performed utilizing human heart left ventricle tissue, HL-1 cells, and murine cardiac slices. Immunostainings revealed that autoantibodies against ICD proteins are prevalent in AC and most autoantibody fractions have catalytic properties and cleave the ICD adhesion molecules DSG2 and N-cadherin, thereby reducing cadherin interactions as revealed by AFM. Furthermore, most of the AC-IgG fractions causing loss of cardiomyocyte cohesion activated p38MAPK, which is known to contribute to a loss of desmosomal adhesion in different cell types, including cardiomyocytes. In addition, p38MAPK inhibition rescued the loss of cardiomyocyte cohesion induced by AC-IgGs. ConclusionOur study demonstrates that catalytic autoantibodies play a pathogenic role by cleaving ICD cadherins and thereby reducing cardiomyocyte cohesion by a mechanism involving p38MAPK activation. Finally, we conclude that DSG2 cleavage by autoantibodies could be used as a diagnostic tool for AC.

cell biology↗

bioRxiv2018

The role of tactile interactions in flight responses in the Bronze Cory catfish (Corydoras aeneus)

One of the primary functions of animal aggregations is defense against predators. Many social animals enjoy reduced predation risk as a result of grouping, and individuals within groups can benefit from information transferred by their group-mates about a potential predator. We present evidence that a tactile interaction behavior we term nudging substantially modified group responses to a potential threat in a highly social catfish species, Corydoras aeneus. These catfish deployed nudges during flight responses, and these nudges were associated with a greater likelihood of group cohesion following a threat event. Increased nudging behavior resulted in longer flight responses. In addition, individuals that perceived the threat first were more likely to initiate nudges, implying that nudges could be used to alert group-mates to the presence of a threat. Taken together, our results suggest that tactile communication plays an important role in gaining anti-predator benefits from sociality in these fish.

animal behavior and cognition↗