Biology subjects

Janfelt, C.

Publications and source records attributed to Janfelt, C..

3 recordsLinked to original sources

bioRxiv2024

Large-Scale Evaluation of Spatial Metabolomics Protocols and Technologies

Spatial metabolomics using imaging mass spectrometry (MS) enables untargeted and label-free metabolite mapping in biological samples. Despite the range of available imaging MS protocols and technologies, our understanding of metabolite detection under specific conditions is limited due to sparse empirical data and predictive theories. Consequently, challenges persist in designing new experiments, and accurately annotating and interpreting data. In this study, we systematically measured the detectability of 172 biologically-relevant metabolites across common imaging MS protocols using custom reference samples. We evaluated 24 MALDI-imaging MS protocols for untargeted metabolomics, and demonstrated the applicability of our findings to complex biological samples through comparison with animal tissue data. We showcased the potential for extending our results to further analytes by predicting metabolite detectability based on molecular properties. Additionally, our interlaboratory comparison of 10 imaging MS technologies, including MALDI, DESI, and IR-MALDESI, showed extensive metabolite coverage and comparable results, underscoring the broad applicability of our findings within the imaging MS community. We share our results and data through a new interactive web application integrated with METASPACE. This resource offers an extensive catalogue of detectable metabolite ions, facilitating protocol selection, supporting data annotation, and benefiting future untargeted spatial metabolomics studies.

systems biology↗

bioRxiv2023

The aerial epidermis is a major site of quinolizidine alkaloid biosynthesis in narrow-leafed lupin

Lupins are promising legume crops that accumulate toxic alkaloids in the seeds, complicating their use as high-protein crops. The alkaloids are synthesized in green organs (leaves, stems, and pods) and a subset of them is transported to the seeds during fruit development. The exact sites of biosynthesis and accumulation remain unknown, however mesophyll cells have been proposed as sources, and epidermal cells have been suggested as sinks. We examined the spatial localization of the alkaloids in biosynthetic organs of narrow-leafed lupin using mass spectrometry-based imaging (MSI). The alkaloids that accumulate in seeds ("core" alkaloids) were evenly distributed across tissues, however their esterified versions accumulated primarily in the epidermis. In addition, we generated a tissue-specific RNAseq dataset of biosynthetic organs using laser-capture microdissection. The dataset revealed that alkaloid biosynthetic genes are strongly expressed in the epidermis. To confirm the biosynthetic capacity of the leaf epidermis, we combined precursor feeding studies with mass spectrometry imaging, which showed that the lower epidermis is highly biosynthetic. Our work challenges the current assumptions on the precise sites of lupin alkaloid biosynthesis, with direct implications for the elucidation of the alkaloid biosynthesis pathway and the long-distance transport network from source to seed.

plant biology↗

bioRxiv2023

Spatiotemporal changes in secondary metabolites during graft formation in grapevine reveal tissue-specific accumulation of metabolites in necrotic and callus tissues

Grafting is widely used in horticulture, shortly after grafting, callus tissues appear at the graft interface and the vascular tissues of the scion and rootstock connect. The graft interface contains a complex mix of tissues, we hypothesized that each tissue have is own metabolic response to wounding/grafting and accumulate different metabolites at different rates. We made intact and wounded cuttings and grafts of grapevine, and then measured changes in bulk secondary metabolite concentration and used metabolite imaging to study tissue specific responses. We show that some metabolites rapidly accumulate in specific tissues after grafting, e.g. stilbenes accumulate in necrotic tissues surrounding mature xylem vessels and gradually oligomerize over time. We also observe that some metabolites accumulate in the newly formed callus tissue at the graft interface and identify genotype-specific responses. Here we reveal the spatiotemporal dynamics of metabolite changes occurring during graft union formation for the first time. The rapid accumulation of stilbenes in the tissues damaged during the grafting process could be a plant defence mechanism, as stilbenes have antioxidant and anti-fungal capacities. The increasing oligomerization of stilbenes often occurs in response to plant stresses (via unknown mechanisms), but it potentially increases antioxidant activity. Brief summarySecondary metabolites accumulate after wounding and grafting in plants yet we have limited knowledge of tissue specific accumulation patterns and temporal dynamics. We show that stilbenes accumulate specifically in necrotic tissues and oligomerize over the time, whereas other compounds accumulate in the newly formed callus tissues. This suggests that these compounds have different roles in wounding healing and grafting.

plant biology↗