Biology subjects

Schmiedova, L.

Publications and source records attributed to Schmiedova, L..

4 recordsLinked to original sources

bioRxiv2023

Investigating the effects of radiation, T cell depletion, and bone marrow transplantation on murine gut microbiota

Microbiome research has gained much attention in recent years as the importance of gut microbiota in regulating host health becomes increasingly evident. However, the impact of radiation on the microbiota in the murine bone marrow transplantation model is still poorly understood. In this paper, we present the major conclusions of our investigation into the effects of radiation and subsequent bone marrow transplantation with or without T cell depletion of the donor bone-marrow on the microbiota of the ileum and cecum. Our findings show that radiation has different effects on the microbiota of the two intestinal regions, with the cecum showing increased interindividual variation, suggesting an impaired ability of the host to regulate microbial symbionts, consistent with the Anna Karenina principle. Additionally, we observed changes in the ileum composition, including an increase in bacterial taxa that are important modulators of host health, such as Akkermansia and Faecalibaculum. In contrast, radiation in the cecum was associated with an increased abundance of several common commensal taxa in the gut, including Lachnospiraceae and Bacteroides. Finally, we found that high doses of radiation had more substantial effects on the caecal microbiota of the T-cell-depleted group than that of the non-T-cell-depleted group. Overall, our results contribute to a better understanding of the complex relationship between radiation and the gut microbiota in the context of bone marrow transplantation and highlight the importance of considering different intestinal regions when studying microbiome responses to environmental stressors.

immunology↗

bioRxiv2023

The effect of host admixture on wild house mouse gut microbiota is weak when accounting for spatial autocorrelation.

The question of how interactions between the gut microbiome and vertebrate hosts contribute to host adaptation and speciation is one of the major problems in current evolutionary research. Using bacteriome and mycobiome metabarcoding, we examined how these two components of the gut microbiota vary with the degree of host admixture in secondary contact between two house mouse subspecies (Mus musculus musculus and M. m. domesticus). We used a large dataset collected at two replicates of the hybrid zone and model-based statistical analyses to ensure the robustness of our results. Assuming that the microbiota of wild hosts suffers from spatial autocorrelation, we directly compared the results of statistical models that were spatially naive with those that accounted for spatial autocorrelation. We showed that neglecting spatial autocorrelation can drastically affect the results and lead to misleading conclusions. The spatial analyses showed little difference between subspecies, both in microbiome composition and in individual bacterial lineages. Similarly, the degree of admixture had minimal effects on the gut bacteriome and mycobiome and was caused by changes in a few microbial lineages that correspond to the common symbionts of free-living house mice. In contrast to previous studies, these data do not support the hypothesis that the microbiota plays an important role in host reproductive isolation in this particular model system.

evolutionary biology↗

bioRxiv2023

Nearly (?) sterile avian egg in a passerine bird

During early ontogeny, microbiome affects development of the gastrointestinal tract, immunity and survival in vertebrates. Bird egg has been suggested to be either (1) initially sterile (Sterile egg hypothesis) and (2) colonized through horizontal trans-shell migration after egg laying, or (3) initially seeded with bacteria through vertical transfer from mother ss oviduct. Little empirical data illuminate so far the contribution of these mechanisms to gut microbiota formation in avian embryos. We evaluated microbiome of the egg content (day 0; E0-egg), embryonic gut at day 13 (E13) and female faeces in a free-living passerine, the great tit (Parus major), using a methodologically advanced procedure combining 16S rRNA gene sequencing and microbe-specific qPCR assays. Our metabarcoding revealed that avian egg is (nearly) sterile, barely distinguishable in microbial composition from negative controls. Of the three potentially pathogenic bacteria targeted by qPCR, only Dietzia was found in E0-egg (yet also in controls), E13 gut and female samples, which might indicate its possible vertical transfer. Unlike in poultry, we have shown in passerines that major bacterial colonisation of the gut does not occur before chicks hatching. We stress that protocols carefully checking for environmental contamination are critically important in studies using samples with low bacterial biomass.

microbiology↗

bioRxiv2020

Phenotypic and clonal stability of antigen-inexperienced memory-like T cells across the genetic background, hygienic status, and aging

Antigen-inexperienced memory-like T (AIMT) cells are functionally unique T cells representing one of the two largest subsets of murine CD8+ T cells. However, differences between laboratory inbred strains, insufficient data from germ-free mice, a complete lack of data from feral mice, and unclear relationship between AIMT cells formation during aging represent major barriers for better understanding of their biology. We performed a thorough characterization of AIMT cells from mice of different genetic background, age, and hygienic status by flow cytometry and multi-omics approaches including analyses of gene expression, TCR repertoire, and microbial colonization. Our data showed that AIMT cells are steadily present in mice independently of their genetic background and hygienic status. Despite differences in their gene expression profiles, young and aged AIMT cells originate from identical clones. We identified that CD122 discriminates two major subsets of AIMT cells in a strain-independent manner. Whereas thymic CD122LOW AIMT cells (innate memory) prevail only in young animals with high thymic IL-4 production, peripheral CD122HIGH AIMT cells (virtual memory) dominate in aged mice. Co-housing with feral mice changed the bacterial colonization of laboratory strains, but had only minimal effects on the CD8+ T-cell compartment including AIMT cells.

immunology↗