Biology subjects

Chakarov, N.

Publications and source records attributed to Chakarov, N..

3 recordsLinked to original sources

bioRxiv2025

Host-parasite interactions of an avian blood parasite elucidated by single-cell transcriptomics

Parasites and hosts perform fine-tuned cellular and molecular interactions, known from few well-explored model systems. Recent methodological advances now allow such deep insights into non-model parasites, their hosts, and their intense reciprocal manipulation. We applied single cell RNA-sequencing to blood samples of a long-lived bird host, infected at high and low intensity with malaria-related parasites. We identify diverse parasitic traits for immune evasion and potential manipulation of the avian host immune response. The transcriptomic response of immune cells was decoupled from the infection load, consistent with evidently low pathogenicity. Changes of immune cell populations showed low activation of adaptive immunity, such as clonal expansion of lymphoid cells. This absence of antagonism indicates immunosuppression by the parasite, which may mitigate virulence and thereby facilitate host-parasite coadaptation. The identified cell-type specific markers provide an important reference and will help to understand the evolutionary forces that shape host immunity in birds. Our study illuminates in rare molecular detail a benign host-parasite interaction and bridges a large coevolutionary knowledge gap of the gradient from parasitism to commensalism and mutualism.

ecology↗

bioRxiv2024

The gut microbiota-immune-brain axis in a wild vertebrate: dynamic interactions and health impacts

The gut microbiota-immune-brain axis is a feedback network which influences diverse physiological processes and plays a pivotal role in overall health and well-being. Although research in humans and laboratory mice has shed light into the associations and mechanisms governing this communication network, evidence of such interactions in wild, especially in young animals, is lacking. We therefore investigated these interactions during early development in a population of common buzzards (Buteo buteo) and their effects on individual condition. In a longitudinal study, we used a multi-marker approach to establish potential links between the bacterial and eukaryotic gut microbiota, a panel of immune assays and feather corticosterone measurements as a proxy for long-term stress. Using Bayesian structural equation modelling, we found no support for feedback between gut microbial diversity and immune or stress parameters. However, we did find strong relationships in the feedback network. Immunity was negatively correlated with corticosterone levels, and microbial diversity was positively associated with nestling body condition. Furthermore, corticosterone levels and eukaryotic microbiota diversity decreased with age while immune activity increased. The absence of conclusive support for the microbiota-immune-brain axis in common buzzard nestlings, coupled with the evidence for stress mediated immunosuppression, suggests a dominating role of stress-dominated maturation of the immune system during early development. Confounding factors inherent to wild systems and developing animals might override associations known from adult laboratory model subjects. The positive association between microbial diversity and body condition indicates the potential health benefits of possessing a diverse and stable microbiota.

microbiology↗

bioRxiv2019

Early sexual dimorphism in the developing gut microbiome of northern elephant seals

The gut microbiome is an integral part of a species ecology, but we know little about how host characteristics impact its development in wild populations. Here, we explored the role of such intrinsic factors in shaping the gut microbiome of northern elephant seals during a critical developmental window of six weeks after weaning, when the pups stay ashore without feeding. We show that the early-life gut microbiome is already substantially different in male and female pups, even though males and females cannot yet be distinguished morphologically. Sex and age both explain around 15% of the variation in gut microbial beta diversity, while microbial communities sampled from the same individual show high levels of similarity across time, explaining another 40% of the variation. Only a small proportion of the variation in beta diversity is explained by health status, but healthy individuals have a greater microbial alpha diversity than their non-healthy peers. Across the post-weaning period, the elephant seal gut microbiome is highly dynamic. We found evidence for several colonisation and extinction events as well as a decline in Bacteriodes and an increase in Prevotella, a pattern that has previously been associated with the transition from nursing to solid food. Lastly, we show that genetic relatedness is correlated with gut microbiome similarity in males but not females, again reflecting substantial early sex-differences. Our study represents a naturally diet-controlled and longitudinal investigation of how intrinsic factors shape the early gut microbiome in a species with extreme sex differences in morphology and life history.

molecular biology↗