Evaluation of Inner Exposure of Horses to Zearalenone (ZEN), Deoxynivalenol (DON) and Their Metabolites in Relation to Colic and Health-Related Clinical-Chemical Traits

Mycotoxin contaminated feed has been associated with colic of horses caused by intestinal disorders. Whether such disease conditions alter the intestinal toxin metabolism and transfer across a compromised mucosal barrier is unknown. A screening approach was used to relate blood residue levels of DON, ZEN and their metabolites to the status of the horses (sick vs. healthy). A total of 55 clinically healthy horses from 6 different farms with varying feeding background served as control for sick horses (N = 102) hospitalized due to colic. ZEN, alpha-zearalenol (ZEL), beta-ZEL and DON were detectable in peripheral blood as indicators for the inner exposure with significant farm effects for alpha- and beta-ZEL. However, the levels in sick horses were similar to all farms. Moreover, the proportion of beta-ZEL of all detected ZEN metabolites as an indicator for the degree of metabolism of ZEN was not different for sick horses but differed amongst the control farms. Although the incidence of DON in blood was generally low and not significantly different amongst healthy and sick horses, the positive samples were nearly exclusively found in sick horses suggesting either a higher toxin transfer, an association of DON with the development of colic or a different feeding background.

Toxin breakdown does not preclude the potential for defensive toxin use in a fruit fly

Animals that ingest toxins can themselves become toxic or unpalatable to predators and parasites. However, most animals rapidly eliminate toxins to survive toxin ingestion. It is therefore unclear how species transition from susceptibility and toxin elimination to tolerance and accumulation as chemical defense emerges. Studies of chemical defense have generally focused on species that display active toxin sequestration and target-site insensitivity mutations that permit survival without necessitating toxin metabolism. Here we investigate whether animals that presumably rely on toxin elimination for survival can also utilize ingested toxins for defense. We use the A4 and A3 Drosophila melanogaster fly strains from the Drosophila Synthetic Population Resource (DSPR), which respectively possess elevated and reduced metabolic toxin resistance. We find that ingesting nicotine increased the survival of A4 but not of A3 flies against Leptopilina heterotoma wasp parasitism. Further, we find that despite possessing enhanced toxin clearance mechanisms, A4 flies accrued more nicotine than A3 individuals. Our results suggest that enhanced metabolic detoxification can allow for greater toxin intake by offsetting the cost of toxin ingestion. Passive toxin accumulation that accompanies increased toxin intake may underlie the early origins of chemical defense.

Current Environmental Health Challenges

This is the first of two overview chapters of important contemporary environmental health challenges. The exciting developments in the environmental health fields are approached in an interdisciplinary manner covering cutting-edge scientific developments and research. In the first chapter, environmental exposures to a variety of toxins, diseases, and stressors that challenge the individual and affect public health are examined. The handling, storage, big data management related to medical and health-informatics are discussed. Issues such as single gene polymorphisms, gene expression, transcriptomics, epigenetics, metabolomics, exposure to carcinogens, endocrine disruptors, heavy metals, physical hazards, airborne particulates, quality of food and water, toxin metabolism, bioinformatics, and exposome analysis are considered. Important recommendations and solutions are provided emphasizing the collaboration between researchers/scientists and the community.

New Invasive Nemertean Species (Cephalothrix Simula) in England with High Levels of Tetrodotoxin and a Microbiome Linked to Toxin Metabolism

The marine nemertean Cephalothrix simula originates from the Pacific Ocean but in recent years has been discovered in northern Europe. The species has been associated with high levels of the marine neurotoxin Tetrodotoxin, traditionally associated with Pufferfish Poisoning. This study reports the first discovery of two organisms of C. simula in the UK, showing the geographical extent of this species is wider than originally described. Species identification was initially conducted morphologically, with confirmation by Cox 1 DNA sequencing. 16S gene sequencing enabled the taxonomic assignment of the microbiome, showing the prevalence of a large number of bacterial genera previously associated with TTX production including Alteromonas, Vibrio and Pseudomonas. LC-MS/MS analysis of the nemertean tissue revealed the presence of multiple analogues of TTX, dominated by the parent TTX, with a total toxin concentration quantified at 54 µg TTX per g of tissue. Pseudomonas luteola isolated from C. simula, together with Vibrio alginolyticus from the native nemertean Tubulanus annulatus, were cultured at low temperature and both found to contain TTX. Overall, this paper confirms the high toxicity of a newly discovered invasive nemertean species with links to toxin-producing marine bacteria and the potential risk to human safety. Further work is required to assess the geographical extent and toxicity range of C. simula along the UK coast in order to properly gauge the potential impacts on the environment and human safety.