Biology subjects

Coleine, C.

Publications and source records attributed to Coleine, C..

5 recordsLinked to original sources

bioRxiv2025

Genomic rearrangements at the MAT locus suggest reproductive shifts in Rhodotorula yeasts

Transitions from canonical outcrossing to rare, cryptic, or noncanonical reproduction are widespread in fungi, but how mating-type (MAT) systems are reorganized at the genomic and population levels during these shifts remains unclear. The coexistence of sexually reproducing species and putatively asexual lineages makes Rhodotorula a natural comparative system for addressing this question. We analyzed 249 globally sampled strains using a combination of long-read and short-read sequencing. Phylogenomics resolved three major clades and several closely related species complexes. Chromosome-scale assemblies confirmed physical separation of the pheromone/receptor (P/R) and homeodomain (HD) loci, whereas non-random P/R-HD associations revealed constrained tetrapolar inheritance. The P/R locus showed conserved synteny within mating types but extensive structural divergence between A1 and A2 alleles, whereas the HD locus remained compact and conserved. Mating-type distributions varied across clades, with both A1 and A2 present in Clade C, lineage-structured partitioning in Clade B, and pronounced A2 dominance in Clade A. Genome-wide linkage disequilibrium (LD) decay in putatively asexual R. mucilaginosa, although slower than in sexual R. diobovata, was consistent with historical recombination in a species without an observed sexual cycle. Clade A further exhibited deep trans-specific polymorphism of STE3.A2 and relaxed purifying selection, mosaic A2 P/R configurations retaining RHA.A1, A1/A2 and A2/A2 hybrid genomes, and A2-associated gene content beyond MAT loci. In conclusion, our findings underscore the dynamic nature of MAT-locus remodeling in Rhodotorula and establish this genus as a valuable model for investigating transitions from heterothallism toward reproductive strategies less dependent on opposite-type partners.

evolutionary biology↗

bioRxiv2024

Novel Glomeromycotina-Moss Associations Identified in California Dryland Biocrusts

Drylands, which comprise ~45% of Earths land area, host biological soil crusts (biocrusts)--symbiotic communities of cyanobacteria, fungi, algae, lichen, and bryophytes that stabilize soil and support key ecosystem functions. Moss dominated biocrusts in particular are interesting due to their potential to illuminate ancient bryophyte-fungal interactions, but their associated microbial communities remain poorly characterized. To test the hypothesis that mosses in biocrusts harbor specific fungal associates, we conducted amplicon metabarcoding and microscopic surveys employing fungal staining across an aridity gradient. We identified novel associations between mosses and arbuscular mycorrhizal fungi (AMF), with phylogenetic analyses revealing distinct fungal communities in moss biocrusts compared to adjacent bare soil. Intracellular branching by fungi resembling Glomeromycotina was observed within healthy Trichostomopsis australaceae cells, suggesting interactions beyond saprotrophy. Moreover, shifts in AMF community composition along an aridity gradient highlight the potential vulnerability of biocrust mycobiomes to climate change. These findings provide critical insights into ancient bryophyte-fungal symbioses, potentially analogous to those enabling early land plant colonization during the Ordovician (~470 Ma). They also underscore the need to understand and protect biocrust microbial communities as aridity intensifies under climate change.

microbiology↗

bioRxiv2022

Highly diverse and unknown viruses may enhance Antarctic endoliths' adaptability

Rock-dwelling microorganisms are key players in ecosystem functioning of Antarctic ice free-areas. Yet, little is known about their diversity and ecology. Here, we performed metagenomic analyses on rocks from across Antarctica comprising >75,000 viral operational taxonomic units (vOTUS). We found largely undescribed, highly diverse and spatially structured virus communities potentially influencing bacterial adaptation and biogeochemistry. This catalog lays the foundation for expanding knowledge of the virosphere in extreme environments.

microbiology↗

bioRxiv2020

Antarctic cryptoendolithic bacterial lineages of pre-Cambrian origin as proxy for Mars colonization

Cryptoendolithic communities are microbial ecosystems dwelling inside porous rocks. They are able to persist at the edge of the biological potential for life in the ice-free areas of continental Antarctica. These areas include the McMurdo Dry Valleys, often cited as a Terrestrial analog of the Martian environment. Despite their interest as a model for the early colonization by living organisms of terrestrial ecosystems and for adaptation to extreme conditions of stress, little is known about the evolution, diversity and genetic makeup of bacterial species that reside in these environments. We performed metagenomic sequencing of 18 communities from rocks collected in Antarctic desert areas over a distance of about 350 km. A total of 469 draft bacterial genome sequences were assembled, and clustered into 269 candidate species that lack a representative genome in public databases. The majority of these new species belong to monophyletic bacterial clades that diverged from related taxa in a range from 1.2 billion to 410 Ma, much earlier than the glaciation of Antarctica, and that are functionally distinct from known related taxa. The hypothesis that Antarctic cryptoendolithic bacterial lineages were generated by the selection of pre-existing cold-tolerant organisms whose origin dates back to the Tonian glaciations gives new insights for the possibility of life on Mars.

microbiology↗

bioRxiv2019

Metagenomes in the borderline ecosystems of the Antarctic cryptoendolithic communities

Antarctic cryptoendolithic communities are microbial ecosystems dwelling inside rocks of ice-free areas in Continental Antarctica. In Antarctica, these ecosystems were first described from the McMurdo Dry Valleys, accounted as the best analogous of the Martian environment on Earth and thought to be devoid of life until the discovery of these cryptic life-forms. Our results present the first shotgun metagenomes of Antarctic cryptoendolithic lichen-dominated communities from 18 differently sun-exposed rock samples collected during the XXXI Italian Antarctic Expedition (2015-16), along an altitudinal transect from 834 up to 3100 m a.s.l. Here, we provide the raw data obtained with Illumina Novaseq sequencer, followed by initial functional and taxonomic analysis.\n\nOur results extend understanding of the microbial diversity and biological processes in the Antarctic desert and represent an invaluable resource for the scientific community as a base-line for further studies of this kind to examine the mechanisms and pathways necessary for life to adapt and evolve in the extremes.

microbiology↗