Genomic investigations of acute munitions exposures on the health and skin microbiome composition of leopard frog (Rana pipiens) tadpolesOriginal paper
Karen Pendergrass is a microbiome researcher specializing in microbiome-targeted interventions (MBTIs). She systematically analyzes scientific literature to identify microbial patterns, develop hypotheses, and validate interventions. As the founder of the Microbiome Signatures Database, she bridges microbiome research with clinical practice. In 2012, based on her own investigative research, she became the first documented case of FMT for Celiac Disease, four years before the first published case study.
Read MoreWhat was studied?
Researchers examined how acute (96 hour) exposure to munitions compounds affects the skin microbiome and health of Rana pipiens (leopard frog) tadpoles. The compounds tested were legacy TNT, the insensitive munition formulation IMX-101, and IM constituents nitroguanidine (NQ) and 1-methyl-3-nitroguanidine (MeNQ).
How was it studied?
Tadpoles were exposed to a range of concentrations of each compound for 96 hours. The team measured survival (LC50 values), profiled the skin microbiome, and used RNAseq to characterize the tadpole host transcriptomic response.
What did they find?
TNT and IMX-101 were lethal at high doses (96h LC50 of 2.6 mg/L for TNT and 68.2 mg/L for IMX-101), while NQ and MeNQ caused no mortality even at thousands of mg/L. All four compounds altered the skin microbiome, significantly increasing relative Proteobacteria abundance with rising exposure, and NQ significantly reduced alpha diversity. TNT and IMX-101 exposure enriched xenobiotic metabolism and heme/iron binding transcriptional pathways in the host, consistent with TNT toxicity mechanisms like hemolytic anemia, while IMX-101 decreased cell cycle pathway expression and NQ enriched immune related gene expression suggestive of immune suppression at high concentrations. MeNQ exposure decreased expression of a keratin gene tied to skin keratinization.
Why it matters
The findings suggest munitions can directly alter amphibian skin microbiome composition, favoring munitions tolerant bacterial groups, while also triggering host transcriptional changes in mucus, antimicrobial peptide, and immune pathways that could indirectly affect microbial communities. Together these effects may influence amphibian disease susceptibility near contaminated Army installation sites.