Biology subjects

McAtamney, A.

Publications and source records attributed to McAtamney, A..

3 recordsLinked to original sources

bioRxiv2025

MALDI-FISH for co-localization of brominated metabolites and Pseudovibrio spp. in Aplysina tissue

Bromotyrosine-containing natural products have long been isolated from marine sponges of the order Verongiida. Recent studies have questioned the source of these natural products whether production occurs through the sponge, its diverse microbiota, or perhaps a combination of both. While studying the uptake of engineered bacterial strains by sponges, we have observed production of fistularin-3 in sponge. To explore these results further, we employed multimodal imaging techniques to co-localize microbial metabolites with fluorescent in situ hybridization (FISH) probes. Here, we built on previously developed MALDI-FISH methods to add to the conversation on brominated metabolite production in marine sponges. Using MALDI-MSI, we measured fistularin-3, a poly-brominated natural product previously isolated from Aplysina aerophoba, present in our A. aerophoba samples that were inoculated with Pseudovibrio brasiliensis. A recent study reported that P. brasiliensis produced fistularin-3 in pure culture, but this data has not yet been reproduced. We employed MALDI-MSI and FISH on the same sponge cryosections to colocalize the spatial distribution of fistularin-3 with P. brasiliensis in sponge tissue. Despite the caveats of this study, our data suggests that perhaps both sponge and microbe may be required for production of fistularin-3.

microbiology↗

bioRxiv2024

Microbial metabolomics' latest SICRIT: Soft ionization by Chemical Reaction in-Transfer mass spectrometry

Microbial metabolomics studies are a common approach to identifying microbial strains that have a capacity to produce new chemistries both in vitro and in situ. A limitation to applying microbial metabolomics to the discovery of new chemical entities is the rediscovery of known compounds, or "known unknowns." One contributing factor to this rediscovery is the majority of laboratories use one ionization source-electrospray ionization (ESI)-to conduct metabolomics studies. Although ESI is an efficient, widely adopted ionization method, its widespread use may contribute to the re-identification of known metabolites. Here, we present the use of a dielectric barrier discharge ionization (DBDI) for microbial metabolomics applications through the use of soft ionization chemical reaction in-transfer (SICRIT). Additionally, we compared SICRIT to ESI using two different Vibrio species-Vibrio fischeri, a symbiotic marine bacterium, and Vibrio cholerae, a pathogenic bacterium. Overall, we found that the SICRIT source ionizes a different set of metabolites than ESI, and it has the ability to ionize lipids more efficiently than ESI in positive mode. This work highlights the value of using more than one ionization source for the detection of metabolites.

biochemistry↗

bioRxiv2023

A label-free approach for relative spatial quantitation of c-di-GMP in microbial biofilms

Microbial biofilms represent an important lifestyle for bacteria and are dynamic three dimensional structures. Cyclic dimeric guanosine monophosphate (c-di-GMP) is a ubiquitous signaling molecule that is known to be tightly regulated with biofilm processes. While measurements of global levels of c-di-GMP have proven valuable towards understanding the genetic control of c-di-GMP production, there is a need for tools to observe the local changes of c-di-GMP production in biofilm processes. We have developed a label-free method for the direct detection of c-di-GMP in microbial colony biofilms using matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI). We applied this method to the enteric pathogen Vibrio cholerae, the marine symbiont V. fischeri, and the opportunistic pathogen Pseudomonas aeruginosa PA14 and detected spatial and temporal changes in c-di-GMP signal that accompanied genetic alterations in factors that synthesize and degrade the compound. We further demonstrated how this method can be simultaneously applied to detect additional metabolites of interest in a single experiment.

microbiology↗