Variability in fecal metabolome depending on age, PFBS pollutant, and fecal transplantation in zebrafish: A non-invasive diagnosis of health

To protect the wellbeing of research animals,certain non-invasive measures are in increasing need to facilitate an early diagnosis of health and toxicity.In this study,feces specimen was collected from adult zebrafish to profile the metabolome fingerprint.Variability in fecal metabolite composition was also distinguished as a result of aging,perfluorobutanesulfonate(PFBS)toxicant,and fecal transplantation.The results showed that zebrafish feces was very rich in a diversity of metabolites that belonged to several major classes,including lipid,amino acid,carbohydrate,vitamin,steroid hormone,and neurotransmitter.Fecal metabolites had functional implications to multiple physiological activities,which were characterized by the enrichment of digestion,absorption,endocrine,and neurotransmission processes.The high richness and functional involvement of fecal metabolites pinpointed feces as an abundant source of diagnostic markers.By comparison between young and aged zebrafish,fundamental modifications of fecal metabolomes were caused by aging progression,centering on the neuroactive ligand-receptor interaction pathway.Exposure of aged zebrafish to PFBS pollutant also significantly disrupted the metabolomic structure in feces.Of special concern were the changes in fecal hormone intermediates after PFBS exposure,which was concordant with the in vivo endocrine disrupting effects of PFBS.Furthermore,itwas intriguing that transplantation of young zebrafish feces efficientlymitigated the metabolic perturbation of PFBS in aged recipients,highlighting the health benefits of therapeutic strategies based on gut microbiota manipulation.In summary,the present study provides preliminary clues to evidence the non-invasive advantage of fecal metabolomics in the early diagnosis and prediction of physiology and toxicology.

Fingerprinting fecal DNA and mRNA as a non-invasive strategy to assess the impact of polychlorinated biphenyl 126 exposure on zebrafish

In toxicological studies,experimental animals are generally subjected to dissection to obtain the tissues of concern,which causes great harm to the animals.In this regard,it is necessary to test and develop a non-invasive strategy to prevent the animals from anthropic injury when achieving scientific objectives.Therefore,zebrafish fecal DNA and mR NA pools were assessed by using metagenomic and transcriptomic analyses based on their potential to diagnose toxicological impairment of polychlorinated biphenyl(PCB)126,a model persistent organic pollutant.The results showed that there was abundant zebrafish DNA and mR NA in the feces,which were,however,associated with contrasting profiles of physiological activities.As compared to DNA fragments,fecal mR NA provided a better representation of zebrafish physiological status.PCB126 exposure dramatically shifted the composition of fecal zebrafish DNA and m RNA as a function of sex.The differential m RNA caused by PCB126 clearly identified the toxicological fingerprint of PCB126.In summary,this study provides preliminary clues about the potential of fecal genes(mRNA in particular)in the development of non-invasive toxicological approaches.In the future,it is expected that more works will be conducted to screen sensitive diagnostic biomarkers from feces to increase the rate and reduce the cost of ecological risk assessment.

Waterborne sub-lethal exposure to perfluorobutanesulfonate causes intestinal dysbiosis in tadpoles of Lithobates catesbeianus

Perfluorobutanesulfonate (PFBS) is a ubiquitous pollutant in the aquatic environment, but its toxic effects andmechanisms on amphibian species remain largely unknown. In the present study, tadpoles (Lithobates catesbeianus) were exposed to various concentrations of PFBS (0, 1, 3, 10, and 30 μg/L) for 14 days, with the goal ofunveiling the impairment of intestinal health. Histopathological examination showed that sub-lethal exposure oftadpoles to PFBS at concentrations as low as 3 μg/L could result in the injury of intestinal structures. In a clearconcentration-dependent manner, the expressions of epithelial barrier components (i.e., Claudin 1 gene and tightjunction protein 2) were significantly decreased in PFBS-exposed intestines, while the intestinal content oflipopolysaccharide (LPS) and transcriptions of downstream responsive genes (e.g., TLR4, MyD88, and NF-κB) wereconcurrently significantly increased by exposure to 3, 10, and 30 μg/L of PFBS. As a consequence, the number ofeosinophils and expression of pro-inflammatory cytokines (e.g., IL-1β and TNF-α) were increased therein.Furthermore, PFBS exposure induced oxidative stress in intestinal tissues by increasing the level of reactive oxygen species (ROS) and suppressing antioxidant capacity. The transcriptional levels of CytoC and Bax genes aswell as activities of caspase 9 and caspase 3 enzymes were remarkably increased, while the transcript abundanceof Bcl-2 was down-regulated significantly after PFBS exposure, thereby favoring apoptosis in tadpole intestines.PFBS sub-lethal exposure also drove the composition of intestinal microbiota to a dysbiosis status. Correlationanalysis further revealed that the relative abundance of members of the genus Bosea was positively related withthe contents of LPS and IL-1β. Overall, the present study provides the first evidence for pronounced impacts ofPFBS on amphibian intestinal ecology, highlighting the susceptibility of tadpoles to the environmental risks ofPFBS.