RESUMO
There are very few studies that have focused on species-specific welfare implications for tigers in a travelling circus. The absence of scientific evidence to inform nationwide legislation means that tigers are still commonly used in travelling circuses across the world. A systematic review of relevant published studies was conducted using the bibliographic databases Web of Science and Scopus, supplemented by a narrative search. In total, 42 relevant studies were identified that assessed the welfare of tigers in captivity, including circuses and zoos. Only eight papers assessed the welfare implications for tigers in circuses directly, evidencing the lack of research in this area. Given that circuses provide a sub-optimal environment compared to zoos, implications for tiger welfare were also inferred from zoo research, within the Five Domains framework. Collectively, these papers infer that the travelling nature of a circus often negatively impacts the welfare domains of nutrition, physical environment, health, and mental state. This is due to limitations in enclosure size, as well as in both environmental and behavioural enrichment. There is also often difficulty in sourcing appropriate food and specialised routine veterinary care. The literature is divided concerning behavioural interactions, specifically whether training can improve welfare by offering mental stimulation. However, circus performances are often associated with negative welfare due to noise disruption from spectators. The collective scientific evidence indicates that tigers are not well suited to circus living, due to the inability of a travelling circus to provide for their species-specific psychological, physiological, and behavioural needs.
RESUMO
The immortalised human hepatocellular HepG2 cell line is commonly used for toxicology studies as an alternative to animal testing due to its characteristic liver-distinctive functions. However, little is known about the baseline metabolic changes within these cells upon toxin exposure. We have applied 1H Nuclear Magnetic Resonance (NMR) spectroscopy to characterise the biochemical composition of HepG2 cells at baseline and post-exposure to hydrogen peroxide (H2O2). Metabolic profiles of live cells, cell extracts, and their spent media supernatants were obtained using 1H high-resolution magic angle spinning (HR-MAS) NMR and 1H NMR spectroscopic techniques. Orthogonal partial least squares discriminant analysis (O-PLS-DA) was used to characterise the metabolites that differed between the baseline and H2O2 treated groups. The results showed that H2O2 caused alterations to 10 metabolites, including acetate, glutamate, lipids, phosphocholine, and creatine in the live cells; 25 metabolites, including acetate, alanine, adenosine diphosphate (ADP), aspartate, citrate, creatine, glucose, glutamine, glutathione, and lactate in the cell extracts, and 22 metabolites, including acetate, alanine, formate, glucose, pyruvate, phenylalanine, threonine, tryptophan, tyrosine, and valine in the cell supernatants. At least 10 biochemical pathways associated with these metabolites were disrupted upon toxin exposure, including those involved in energy, lipid, and amino acid metabolism. Our findings illustrate the ability of NMR-based metabolic profiling of immortalised human cells to detect metabolic effects on central metabolism due to toxin exposure. The established data sets will enable more subtle biochemical changes in the HepG2 model cell system to be identified in future toxicity testing.