Biology subjects

Pot, G.

Publications and source records attributed to Pot, G..

3 recordsLinked to original sources

bioRxiv2026

Nutritional Anthelmintics: Chicory Reconfigures the Equine Holobiont Across Microbial, Parasitic, and Host Scales

Anthelmintic resistance in cyathostomins is escalating worldwide, threatening equine health and highlighting the need for sustainable, ecology-based parasite control strategies. Chicory (Cichorium intybus, Puna II) has emerged as a promising antiparasitic forage, yet its broader effects on the equine holobiont, parasites, microbiota, and host physiology remain poorly understood. We conducted a 32-day longitudinal grazing trial in young horses to assess how chicory affects parasitological outcomes, gut microbial ecology, nemabiome composition, behaviour, and host physiological and immune responses. Twenty-six naturally infected Anglo-Arabian horses were monitored weekly, with 13 grazing a chicory-based sward and 13 grazing a permanent pasture. Clinical parameters, body weight, and serum biochemistry remained stable across treatments, indicating that chicory was well tolerated. Immune profiles showed limited variation, although IL-10 increased in chicory-fed horses, suggesting subtle immune modulation. Behavioural observations revealed no signs of discomfort and indicated slightly enhanced social interactions in the chicory group. Chicory grazing produced a marked reduction in cyathostomin egg excretion, accompanied by species-specific shifts in nemabiome composition. Several cyathostomin taxa, including Cylicocyclus ashworthi, C. leptostomus, and C. nassatus, declined in chicory-fed horses, whereas certain Cylicostephanus spp increased, indicating differential sensitivity rather than uniform suppression. Concomitantly, chicory induced profound ecological changes in the gut microbiota, including reduced alpha diversity, increased beta dispersion, and destabilised individual microbial trajectories. Several bacterial lineages, particularly Oscillospiraceae, Clostridiaceae, Lachnospiraceae, and Bacteroidales, were differentially enriched, reflecting a functional reorganisation of the intestinal ecosystem. Together, these findings demonstrate that chicory reduces parasite fitness, reshapes nemabiome composition, and alters gut microbial ecology while maintaining host physiological stability. Chicory thus emerges as a promising ecological tool for parasite control, capable of modulating the equine holobiont in ways that complement and potentially reduce reliance on conventional anthelmintic strategies. However, because its effects on gut microbial ecology remain uncertain, and may include shifts resembling dysbiosis, future studies are needed to monitor microbial dynamics more closely and clarify the long-term ecological consequences of chicory grazing. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=136 SRC="FIGDIR/small/737212v1_ufig1.gif" ALT="Figure 1"> View larger version (48K): org.highwire.dtl.DTLVardef@7b7367org.highwire.dtl.DTLVardef@d5914aorg.highwire.dtl.DTLVardef@135ad65org.highwire.dtl.DTLVardef@10b0322_HPS_FORMAT_FIGEXP M_FIG C_FIG

systems biology↗

bioRxiv2025

Nucleoside Binding by a Surface Lipoprotein Governs Conjugative ICE Acquisition in Ruminant Mycoplasmas

Integrative and conjugative elements (ICEs) are major mediators of horizontal gene transfer (HGT) in bacteria. However, the role of recipient cells in their acquisition has received little attention. Using the ruminant pathogens Mycoplasma agalactiae and Mycoplasma bovis as minimal models, we combined genome-wide transposon mutagenesis with high-throughput mating assays to identify recipient factors required for ICE acquisition. The surface lipoprotein P48 emerged as the primary determinant of ICE uptake in both species. Structural and functional analyses revealed that P48 is the substrate-binding component of an ABC transporter with nucleoside-binding capacity. A single point mutation that abolished nucleoside binding drastically reduced ICE acquisition, demonstrating that P48-mediated nucleoside recognition is essential for conjugative transfer. However, ICE uptake did not require nucleoside transport, as inactivation of the transporter permease blocked nucleoside analog toxicity but not ICE invasion. Loss of P48 also triggered transcriptional activation of vestigial ICE genes, suggesting that surface recognition affects the intracellular state of the recipient. Remarkably, ICE transmission from recipient-derived donors was unaffected by P48 loss, underscoring its acquisition-specific role. Together, these results reveal a previously unrecognized, surface-exposed recipient factor critical for efficient ICE transfer in mycoplasmas and identify nucleotide binding as a central function in conjugation. By demonstrating that recipient-encoded functions can directly control ICE dissemination, this work challenges the donor-centric paradigm of bacterial conjugation and suggests new strategies to restrict horizontal gene flow in pathogenic and synthetic mycoplasmas. IMPORTANCEIntegrative and conjugative elements (ICEs) are mobile DNA elements that drive bacterial conjugation, a major process by which bacteria exchange genes. Although conjugation has been studied for decades, the focus has been almost exclusively on donor cells and the ICE itself, leaving the role of recipient cells largely overlooked. Using the wall-less ruminant pathogens Mycoplasma agalactiae and Mycoplasma bovis as minimal models, we discovered that a single recipient lipoprotein is required for efficient ICE uptake. Our data show that nucleoside recognition by P48, but not transport, is critical for conjugation, revealing an unexpected mechanistic link between nutrient sensing and gene acquisition. These findings shift the paradigm of conjugation from a donor-driven process to one jointly determined by donor and recipient functions. By identifying a recipient-encoded determinant of ICE transfer, this work opens new avenues to control horizontal gene flow in both pathogenic and engineered bacteria. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=151 SRC="FIGDIR/small/677790v1_ufig1.gif" ALT="Figure 1"> View larger version (26K): org.highwire.dtl.DTLVardef@f7cc15org.highwire.dtl.DTLVardef@77a34eorg.highwire.dtl.DTLVardef@82699corg.highwire.dtl.DTLVardef@1e3be93_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2025

Bacterial Conjugation in the Ruminant Pathogen Mycoplasma agalactiae is Influenced by Eukaryotic Host Factors

Bacterial conjugation plays a pivotal role in the evolution and adaptation of genome-reduced mycoplasmas. Despite their fast evolution rate, the conjugative properties of these organisms remain largely understudied, particularly in vivo. In the present study, the ruminant pathogen Mycoplasma agalactiae was used as a model organism to document the conjugative properties of mycoplasmas in environments of increasing complexity, from axenic to cell and organotypic culture conditions. Compared to axenic mating conditions, mycoplasma co-cultivation with goat epithelial cells or bovine precision-cut lung slices (PCLS) resulted in enhanced mating frequencies with high rates of M. agalactiae Integrative and Conjugative Element (ICEA) self-dissemination. These results were conditioned by the presence of eukaryotic cells in the culture and influenced by competition between mating partners but were not limited to M. agalactiae, as similar results were observed with Mycoplasma bovis. Mycoplasma conjugation ex vivo was further characterized by analyzing mycoplasma chromosomal transfer (MCT), a newly discovered mechanism of horizontal exchange of chromosomal DNA that generates mosaic genomes. Although closely associated with ICEA transfer, MCT was detected at low rates under cell and organotypic culture conditions suggesting a complex interplay between these two conjugative processes or a poor viability of the MCT progeny. Finally, mating experiments under nutrient-deprived conditions identified nucleotide stress as a potential factor influencing the modulation of mycoplasma conjugation by eukaryotic host cells. In conclusion, these results suggest that horizontal gene transfer in vivo is likely underestimated and provide valuable models to further studying mycoplasma conjugation ex vivo. IMPORTANCEConjugation is an evolutionary shortcut that bacteria use to exchange genetic information with their neighbors. Despite the fast evolution rate of the genome-reduced mycoplasmas, their conjugative properties remain largely understudied, particularly in vivo. Here we used the ruminant pathogen Mycoplasma agalactiae to study how mycoplasmas conjugate in co-culture with hosts-derived cells and tissues. Interestingly, conjugation was stimulated when mycoplasmas were co-cultured with eukaryotic cells. This was documented by monitoring the self-propagation of a mobile genetic element known as Integrative and Conjugative Element (ICE) and the exchange of chromosomal DNA leading to the formation of mosaic genomes. While ICE transfer was observed at high frequency, only a few mosaic genomes were detected in the presence of eukaryotic cells. Further data point towards nucleotide stress as a possible factor modulating mycoplasma conjugation in cellular environments. These results suggest that mycoplasma-host interactions may stimulate conjugation in vivo.

microbiology↗