Biology subjects

Jelinek, V.

Publications and source records attributed to Jelinek, V..

5 recordsLinked to original sources

bioRxiv2025

Dissecting GPCR Selectivity: A complex interplay of various intracellular motifs determines G-protein binding and activation

G-Protein coupled receptors (GPCRs) mediate intracellular signaling by selectively activating heterotrimeric G-proteins. While certain GPCRs exhibit a high specificity toward particular G-protein subtypes, other GPCRs display promiscuous signaling by engaging interaction with multiple G-protein families. Molecular determinants underlying the selectivity or promiscuity of the receptors remain incompletely understood. In the present study, we investigate various structural motifs within the intracellular domains of Muscarinic receptors to assess their role in both G subunit binding and activation. To this end, we generated chimeric receptors and applied both FRET- and BRET-based assays to monitor G protein binding and activation. Our study demonstrates that the determination of G-protein coupling selectivity is not defined by single motifs or amino acids but rather by a complex interplay of various intracellular motifs affecting binding or/and subsequent activation. These results provide new insights into the structural basis of GPCR-G protein specificity.

pharmacology and toxicology↗

bioRxiv2025

Conspecific brood parasitism in the barn swallow (Hirundo rustica)

Conspecific brood parasitism (CBP) has been reported in many altricial avian species, yet its prevalence and underlying behavioural mechanisms remain poorly understood. We studied CBP in the barn swallow (Hirundo rustica), a species in which conspecific brood parasitism has been reported. We conducted parentage analysis on 1945 barn swallow broods involving 7816 offspring. Samples were collected over 12 breeding seasons at 5 colonies/populations. Contrary to expectations, we identified only six cases of CBP (0.3 % of broods). By identifying all individuals involved, i.e. the parasitic females, the female hosts and the males that fathered the parasitic eggs, we determined these cases of CBP resulted most likely from either a failed nest take-over (three times), the disappearance of a female partner or a disruption caused by researchers while only one case could be interpreted as a result of females mixed reproductive tactic. Based on a review of the literature on CBP in seven other Hirundinidae, we conclude that the only reliable evidence for CBP comes from cliff swallows (Petrochelidon pyrrhonata). Studies on other species either failed to identify the parasitic females or do not present sufficient evidence supporting the occurrence of CBP. Several studies relied on the appearance of two eggs in a nest within 24 hours to conclude that CBP occurred. However, based on the parentage analysis, we show that CBP only occurred in one out of 11 such cases in our barn swallow data. Our findings highlight that CBP is rare in our barn swallow populations, and have been likely overestimated in other studies. We emphasize the importance of frequent nest checks and rigorous genetic validation in CBP research. Overall, our results challenge existing assumptions about the prevalence of CBP and provide insights into the behavioural mechanisms that lead to CBP, with ecological and evolutionary implications.

ecology↗

bioRxiv2025

Recent breeding experience improves egg ejection behaviour

Recognizing ones own eggs is crucial for birds, especially for hosts of brood parasites that must identify and reject different-looking parasitic eggs. While birds seem to possess a template image of their eggs, whether it is innate or learnt remains unclear. We addressed this question by experimentally inserting either artificial mimetic eggs (ME) or non-mimetic eggs (NME) into the nests of barn swallows (Hirundo rustica) during pre-laying stage. Our individually marked population allowed a unique comparison between naive first-time breeders and experienced females, as well as females with old (from a previous season) and recent (from the previous breeding attempt within the same season) experience allowing to investigate the role of memory. We found that both naive and experienced females ejected ME and NME at similar rates, indicating that the template image is neither innate nor learnt and does not play a primary role in egg recognition. Instead, our findings suggest that awareness of own egg-laying is the crucial mechanism at play, and may facilitate nest sanitation behaviour. Finally, we provide the first evidence that this mechanism improves with recent breeding experience. Future studies should investigate the role of non-visual factors that may modulate nest sanitation, such as endocrine regulation.

animal behavior and cognition↗

bioRxiv2024

Machine learning outcompetes human assessment in identifying eggs of a conspecific brood parasite

Avian brood parasitism provides an exceptional system for studying coevolution. While conspecific brood parasitism (CBP) is more common than interspecific parasitism, it is less studied due to the challenge of detecting parasitic eggs, which closely resemble those of the host. Although molecular genotyping can accurately detect CBP, its high cost has led researchers to explore egg appearance as a more accessible alternative. Barn swallows (Hirundo rustica) are considered conspecific brood parasites, but identifying parasitic eggs has traditionally relied on human visual assessment. Here, we used UV-visible photographs of non-parasitized barn swallow clutches and simulated parasitism to compare the accuracy of human assessment with automated methods. In two games, participants and models identified parasitic eggs from six or two options. While humans performed better than chance (72% and 87% accuracy), they still made significant errors. In contrast, the automated supervised model was far more reliable, achieving 95% and 97% accuracy. We think that the model outperformed humans due to its ability to analyse a broader range of visual information, including UV reflectance, which humans cannot perceive. We recommend using supervised models over human assessment for identifying conspecific parasitic eggs and highlight their potential to advance research on evolution of egg colouration.

zoology↗

bioRxiv2020

Fast and furious: host aggression modulates behaviour of brood parasites

Avian brood parasites pose a serious threat for hosts, substantially reducing their fitness which selects for the evolution of host defences. A classic example of a host frontline defence is mobbing which frequently includes contact attacking of brood parasites. Here, we investigated how the nest defence of a very aggressive great reed warbler (Acrocephalus arundinaceus) host influences the speed of egg-laying and egg-removing behaviour of its brood parasite - the common cuckoo (Cuculus canorus). We video-recorded 168 brood parasitic events at 102 active host nests and found that cuckoos avoided host mobbing in only 62% of cases. If hosts spotted the cuckoo at their nests, they almost always attacked it (in 91 of 104 cases), however, such attacks only rarely and temporarily prevented cuckoos from parasitizing (11 additional cases). When attacked, cuckoos parasitized host nests significantly faster and left them immediately. However, when not attacked, cuckoos frequently stayed at or near the nest suggesting that host aggression, rather than the risk of being spotted, influences the speed of brood parasitism in this species. Further, we found that cuckoos performed egg-removing behaviour in all parasitic events without regard to host aggression. As a result, cuckoos removed at least one egg during all brood parasitism events except those when an egg slipped from their beaks and fell back into the nest (in 9 of 73 cases). This indicates that egg-removing behaviour is not costly for the common cuckoo and is an essential part of its parasitism strategy, widening understanding of this currently unexplained behaviour.

ecology↗