Biology subjects

Salonen, I.

Publications and source records attributed to Salonen, I..

3 recordsLinked to original sources

bioRxiv2026

Differing patterns in community composition and diversity of biofilm-forming bacteria and fungi along a large salinity gradient

Aim: Biofilms are complex ecosystems formed by phototrophic and heterotrophic organisms, such as bacteria and fungi. Biofilms are hotspots for microbial activity and crucial for the functioning of all aquatic ecosystems, but they are overlooked and poorly studied, especially along large environmental gradients. We aimed at resolving the responses of bacterial and fungal communities to environmental variation along a gradient with strong variation in environmental factors, especially salinity. We also investigated whether the diversity of biofilm-forming bacteria and fungi follows the pattern predicted by the Remane curve, which posits that species diversity is lowest at intermediate salinity. Location: 2300-km-long spatial gradient in the Baltic Sea, Northern Europe Time period: August 2018 Major taxa studied: Biofilm-forming bacteria and fungi Methods: We investigated the composition and diversity of bacteria and fungi by collecting biofilm samples from 42 shallow benthic ecosystems. We also characterized key environmental variables, such as salinity, nutrient concentrations, wind exposure, and climatic conditions. Bacterial and fungal communities in biofilm samples were identified using Illumina MiSeq sequencing. Results: We found that bacteria and fungi responded differently to environmental variation. Bacterial communities were mainly controlled by salinity, and their diversity was lowest in the intermediate salinity. Bacterial communities were also dominated by different bacterial orders in high, intermediate, and low salinity. Fungal communities, instead, were jointly controlled by several environmental variables, i.e., salinity, water temperature, wind exposure, and nutrients, and their diversity or composition did not show a clear pattern along the salinity gradient. Main conclusions: To our knowledge, this is one of the first studies to investigate the biofilm-forming communities, especially fungal communities, along large environmental gradients. Our results highlight the role of biofilms as complex ecosystems where organisms ecological requirements are unique and variable.

ecology↗

bioRxiv2026

Multi-region whole-genome and transcriptomic profiling uncovers plastic, subclone-linked cell states in high-grade diffuse astrocytomas

Intratumoral heterogeneity is a defining feature of high-grade astrocytomas and a major contributor to treatment resistance. Yet how genomic diversification intersects with transcriptional plasticity remains incompletely understood. We performed high-resolution multi-omic profiling of three complex, treatment-naive tumors (two IDH-wildtype glioblastomas and one IDH-mutant grade 4 astrocytoma). By integrating whole-genome sequencing (WGS), bulk and single-cell RNA sequencing (scRNA-seq), and histopathology across four anatomically distinct regions per tumor, we mapped the co-evolution of genome and transcriptome. Despite striking regional differences in morphology and cellular states, genomic evolution was predominantly trunk-dominated. Most driver alterations were clonal across regions, indicating early acquisition and stable genomic backbones. The IDH-mutant tumor showed linear evolution with localized hypermutation, whereas glioblastomas displayed modest late-branching subclones. In contrast, transcriptional heterogeneity was pronounced and spatially structured. Distinct genetic subclones preferentially occupied divergent transcriptional states. However, subclones shared across regions frequently adopted different phenotypes depending on local microenvironment. Single-cell reconstruction from matched patient-derived cell lines resolved subclone-associated trajectories, revealing dynamic transitions between proliferative and inflammatory states. This study provides a framework for understanding how early-established genomic backbones and regional transcriptional plasticity jointly drive phenotypic diversity. While single biopsies may capture truncal drivers, resolving clinically relevant heterogeneity requires multi-region and single-cell approaches.

cancer biology↗

bioRxiv2026

Hypoxia and Associated Acidosis Generate Cell-Type Specific Myeloid Responses in Glioblastoma

Hypoxia is a defining feature of glioblastoma (GBM), yet how it cooperates with hypoxia-associated acidosis to shape microglia and infiltrating monocyte-derived macrophages (MDM) remains poorly understood. We integrated cyclic immunohistochemistry, single-cell RNA sequencing, spatial transcriptomics, in vitro cell cultures, and DNA methylation profiling to outline hypoxia-driven responses in up to 136 GBMs. These hypoxic niches were selectively enriched for MDMs that activated carbonic anhydrase (CA) mediated pH buffering and other metabolic adaptation programs, enabling survival in acidic hypoxia, increasingly interacted with cancer cells, and show polarization toward immunosuppressive myeloid-derived suppressor cell (MDSC)-like states. In contrast, microglia were depleted in hypoxic areas, lacked compensatory CA isoenzymes, and developed TNF-linked stress responses and loss of homeostatic identity in acidic hypoxia. These findings identify metabolic adaptation to hypoxia-associated microenvironmental stress as a key determinant of GBM immune architecture, driving myeloid cell fates, spatial TME reorganization and the emergence of immunosuppressive tumor ecosystems.

cancer biology↗