Metabolic disruptions and impaired reproductive fitness in wild-caught freshwater turtles (Emydura macquarii macquarii) exposed to elevated per- and polyfluoroalkyl substances (PFAS).

Per- and poly-fluoroalkyl substances (PFAS) pose a threat to organisms and ecosystems due to their persistent nature. Ecotoxicology endpoints used in regulatory guidelines may not reflect multiple, low-level but persistent stressors. This study examines the biological effects of PFAS on Eastern short-necked turtles in Queensland, Australia. In this study, blood samples were collected and analysed for PFAS, hormone levels, and functional omics endpoints. High levels of PFAS were found in turtles at the impacted site, with PFOS being the dominant constituent. The PFAS profiles of males and females differed, with males having higher PFAS concentrations. Hormone concentrations differed between impacted and reference sites in male turtles, with elevated testosterone and corticosterone indicative of stress. Further, energy utilisation, nucleotide synthesis, nitrogen metabolism, and amino acid synthesis were altered in both male and female turtles from PFAS-impacted sites. Both sexes show similar metabolic responses to environmental stressors from the PFAS-contaminated site, which may adversely affect their reproductive fitness. Purine metabolism, caffeine metabolism, and ferroptosis pathway changes in turtles can cause gout, cell death, and overall health problems. Further, the study showed that prolonged exposure to elevated PFAS levels in the wild could compromise turtle reproductive fitness by disrupting reproductive steroids and metabolic pathways.

Perturbation of the gut microbiome in wild-caught freshwater turtles (Emydura macquarii macquarii) exposed to elevated PFAS levels.

Per- and polyfluoroalkyl substances (PFAS) are environmentally persistent and pervasive. Understanding the toxicity of PFAS to wildlife is difficult, both due to the complexity of biotic and abiotic perturbations in the taxa under study and the practical and ethical problems associated with studying the impacts of environmental pollutants on free living wildlife. One avenue of inquiry into the effects of environmental pollutants, such as PFAS, is assessing the impact on the host gut microbiome. Here we show the microbial composition and biochemical functional outputs from the gut microbiome of sampled faeces from euthanised and necropsied wild-caught freshwater turtles (Emydura macquarii macquarii) exposed to elevated PFAS levels. The microbial community composition was profiled by 16S rRNA gene sequencing using a Nanopore MinION and the biochemical functional outputs of the gut microbiome were profiled using a combination of targeted central carbon metabolism metabolomics using liquid chromatography coupled to a triple quadrupole mass spectrometer (LC-QqQ-MS) and untargeted metabolomics using liquid chromatography coupled to a quadrupole time of flight mass spectrometer (LC-QToF-MS). Total PFAS was measured in the turtle serum using standard methods. These preliminary data demonstrated a 60-fold PFAS increase in impacted turtles compared to the sampled aquatic environment. The microbiome community was also impacted in the PFAS exposed turtles, with the ratio of Firmicutes-to-Bacteroidetes rising from 1.4 at the reference site to 5.5 at the PFAS impacted site. This ratio increase is indicative of host stress and dysfunction of the gut microbiome that was correlated with the biochemical metabolic function data, metabolites observed that are indications of stress and inflammation in the gut microbiome. Utilising the gut microbiome of sampled faeces collected from freshwater turtles provides a non-destructive avenue for investigating the impacts of PFAS in native wildlife, and provides an avenue to explore other contaminants in higher-order taxa within the environment.

The Efficiency of Color Space Channels to Quantify Color and Color Intensity Change in Liquids, pH Strips, and Lateral Flow Assays with Smartphones.

Bottom-up, end-user based feed, and food analysis through smartphone quantification of lateral flow assays (LFA) has the potential to cause a paradigm shift in testing capabilities. However, most developed devices do not test the presence of and implications of inter-phone variation. Much discussion remains regarding optimum color space for smartphone colorimetric analyses and, an in-depth comparison of color space performance is missing. Moreover, a light-shielding box is often used to avoid variations caused by background illumination while the use of such a bulky add-on may be avoidable through image background correction. Here, quantification performance of individual channels of RGB, HSV, and LAB color space and ΔRGB was determined for color and color intensity variation using pH strips, filter paper with dropped nanoparticles, and colored solutions. LAB and HSV color space channels never outperformed the best RGB channels in any test. Background correction avoided measurement variation if no direct sunlight was used and functioned more efficiently outside a light-shielding box (prediction errors < 5%/35% for color/color intensity change). The system was validated using various phones for quantification of major allergens (i.e., gluten in buffer, bovine milk in goat milk and goat cheese), and, pH in soil extracts with commercial pH strips and LFA. Inter-phone variation was significant for LFA quantification but low using pH strips (prediction errors < 10% for all six phones compared). Thus, assays based on color change hold the strongest promise for end-user adapted smartphone diagnostics.