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McCallum, P.

Publications and source records attributed to McCallum, P..

3 recordsLinked to original sources

Rapid early life colonization of the intestinal tract by Akkermansia muciniphila after voluntary feeding

BackgroundNon-invasive methods to colonize intact gut microbiota populations with specific bacterial species are useful for experimental studies that advance our understanding of this commensal microbial population in health and disease. Within the gut microbiota, the anaerobic muciniphile Akkermansia muciniphila has many established health benefits. We report the development of a new voluntary feeding protocol for non-invasive administration of bacteria into the intestine and use it to characterize the early life colonization of the intestinal tract by A. muciniphila. ResultsMice were voluntarily fed a human strain of A. muciniphila (MucT/BAA-835) in the week after weaning, whereupon they consistently and rapidly ingested the bacterium. At this developmental period, conventionally housed mice were rapidly colonized by human A. muciniphila that persisted until at least 8 weeks of age. In mice that contained a dysbiotic gut microbiota that lack endogenous A. muciniphila, voluntary feeding with human A. muciniphila similarly led to rapid and stable colonization. Colonization was similar in female and male mice. Also, in conventionally housed mice there was incomplete colonization of the intestinal tract with endogenous A. muciniphila between 3 - 4 weeks of age, which enabled its competitive exclusion by human A. muciniphila that was orally delivered. ConclusionsThese findings establish a new and non-invasive approach for colonizing the intestinal tract with commensal microbes that provides information on the early life colonization of the gut microbiota with A. muciniphila.

microbiology↗

PASTA: Versatile Tyramine-oligonucleotide Amplification for Multi-modal Spatial Biology

Spatial proteomics techniques have revolutionized our understanding of tissue architecture, but are frequently limited by detection sensitivity, bioconjugation limitations, multiplexing capacity, and multi-modal integration. Here we present Protein and nucleic Acid Serial Tyramine Amplification (PASTA), a novel signal amplification approach that significantly enhances detection sensitivity while maintaining compatibility with diverse spatial profiling methodologies. PASTA utilizes horseradish peroxidase (HRP) recruitment pathways to generate tyramine radicals that deposit oligonucleotides, enabling adaptable signal amplification across multiple biomarkers at high-plex via cyclical imaging using complementary fluorophore-labeled oligonucleotides. We demonstrate that PASTA achieves up to 100-fold signal enhancement for markers with minimal background in blank controls. The method is compatible with in situ hybridization for DNA/RNA detection, proximity ligation assays for protein-protein interactions, sequential antibody staining protocols, or any modular combination thereof. PASTA enables antibody rescue of markers with suboptimal signal-to-noise ratios and is versatile in its applications to unconjugated antibodies, and multi-round probe-based RNA detection systems beyond current capabilities. This technique addresses key limitations in spatial-omics by enhancing sensitivity for challenging targets while maintaining compatibility with established multiplexing strategies, providing a versatile, cost-efficient, and valuable tool for comprehensive spatial tissue analysis in both research and clinical applications.

molecular biology↗

Tunable PhenoCycler Imaging of the Murine Pre-Clinical Tumour Microenvironments

The tumour microenvironment (TME) consists of tumour-supportive immune cells, endothelial cells, and fibroblasts. PhenoCycler, a high-plex single cell imaging platform, is used to characterize the complexity of the TME. Here, we used PhenoCycler to spatially resolve the TME of 8 routinely employed pre-clinical models of lymphoma, breast cancer, and melanoma. Our data reveal distinct TMEs in the different cancer models that were imaged, and show that cell-cell contacts differ depending on the tumour type examined. For instance, we found that the immune infiltration in a murine model of melanoma is altered in cellular organization in melanomas that become resistant to PD-1 therapy, with depletions in a number of cell-cell interactions. Furthermore, we provide detailed pipelines for the conjugation of antibodies that are optimized for PhenoCycler staining of murine FFPE tissues specifically, alongside open-source data analysis procedures. Overall, this is a valuable resource study seamlessly adaptable to any field of research involving murine models.

cancer biology↗