The emerging flame retardants pentabromobenzene (PBB) has been frequently detected in recent years and may pose exposure risks to wild animals and human beings. In this study, the inflation of posterior swim bladder of zebrafish larvae was used as an endpoint to study the developmental toxicity and putative mechanisms associated with PBB toxicity. Our results showed that embryonic exposure to PBB could significantly inhibit the inflation of posterior swim bladders. Reduced T3 levels and transcriptional changes of crh and pomc were observed in PBB treated zebrafish larvae at 120 hpf. However, key regulators of thyroid and adrenocortical system involved in the synthesis (tsh), biological conversion (ugt1ab, dio2) and functional regulation (trα, trβ, gr) showed no significant changes. Further data revealed that prlra was the only gene that was altered among the detected genes at 96 h post fertilization (hpf). At 120 hpf, the morphology of swim bladder indicated deflation in treatments at 0.25 μM and higher. In addition, the mRNA levels of anxa5, prlra, prlrb, atp1b2 and slc12a10 were all significantly changed at 120 hpf. Taken together, we suppose that embryonic exposure to PBB inhibited the inflation of swim bladder in zebrafish probably via prlra mediated pathways. The observed changes of thyroid and adrenocortical parameters might be indirect effects evoked by PBB exposure. Overall, our results provide important data and indications for future toxicological study and risk assessment of the emerging flame retardants PBB.

Heavy metal contamination is a serious environmental problem commonly monitored in various organisms. Small wild rodents are ideal biological monitors to show the extent of environmental pollution. The aim of this study was to evaluate the adverse effects of marble and stone quarries on the Levant vole, Microtus guentheri, inhabiting some polluted sites. In this context, Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was used to analyze distribution of thirteen heavy metals (Fe, Al, Zn, Cu, Cr, Mn, Ni, B, Pb, As, Co, Cd, and Hg) in the organs (skins, bones, muscles, livers and kidneys) of the biological specimens, and the comet assay revealed DNA damage in blood lymphocytes for the first time. This study was conducted at close to the marble and stone quarries at Korkuteli, Antalya-Turkey during spring, summer, autumn (2017) and winter (2018) seasons. In spring and summer, genetic damage in blood lymphocytes from all polluted sites (sites 1–5) was significantly higher than that of controls, while in autumn it was higher in samples from three sites (sites 3–5). In terms of heavy metal distribution in organs, we found depositions of Fe, Al, Zn, Ni, Mn, Cr, Co, As and Pb primarily in the skin with its derivatives, Cu and Cd deposits in the kidney, Cu, Cd and B deposits in the liver, and As and Pb depositions in the bones. The study shows that certain organs (especially skin with its derivatives) and blood lymphocytes of Levant vole can be used as ideal indicators of heavy metal pollution. Our results suggest that the Korkuteli area could already be under the threat of heavy metal pollution.

Increasing urbanisation is altering the physiology of wild animals and the mechanisms involved are largely unknown. We hypothesised that altering the physiology of urban organisms is due to the effect of extra light at night on the circadian clock by modulating the expression of pineal machinery and clock genes. Two experiments were performed. In Experiment 1, immediately after being procured from their respective sites (urban and rural sites), birds were released individually in LLdᵢₘ light conditions. Circadian rhythm period, activity duration, and total activity count were calculated and did not differ between urban and rural birds. In Experiment 2, birds (from urban and rural habitats) were sampled at six time points at regular 4-h intervals, beginning 1 h after sunrise. We measured daily variations in plasma melatonin levels. We also analysed the expression levels of Aanat, Mel1A and Mel1B as an indicator of melatonin biosynthesis and action machinery. Clock and clock-controlled genes (Bmal1, Clock, Per2, Per3, Cry1 and Npas2) were studied in the hypothalamus, the pineal gland, and retina to investigate the effects of urban habitats on the circadian clock. Our results show that there is a lower expression of Aanat in the pineal gland and relatively low plasma melatonin levels in urban birds. Further, clock genes are also differentially expressed in all three central tissues of urban birds. We propose that alterations in the melatonin biosynthesis machinery and the expression of clock genes could result in miscalculations in the internal timing of the organism, with environmental timings leading to altered physiology in urban wild animals.

Research using various species of wild and cultured fish has identified negative effects of short-term exposure to microbeads. Although wild animals might be contaminated with microbeads and/or other pharmaceuticals, data regarding the long-term effects remain limited. To clearly elucidate the effects of microbeads, studies of long-term exposure using animal models are necessary. Our aim was to elucidate the effects of microbeads alone on the growth and fecundity of medaka following long-term exposure (12 weeks). In experiment 1, fish groups (except controls) were temporarily exposed to polyethylene microbeads (10–63 μm diameter) a low dose of 0.065 microbeads-mg/L and high dose of 0.65 microbeads-mg/L. In experiment 2, see-through medaka and fluorescent polyethylene microbeads (10–45 μm diameter) were used to estimate the retention time of ingested microbeads in the digestive tract, which was 4–9 days. The low dose of microbeads did not affect growth but did decrease the number of eggs and the hatching rate. The high dose decreased growth, the number of eggs, and hatching rate. Growth differences were recognized for the first time at 7 weeks, and differences in the number of eggs at 12 weeks. Thus, long-term tests using medaka indicated that microbeads per se exhibit growth inhibition and reproductive toxicity. These effects could be associated with nutritional factors resulting from the long retention time of microbeads in the digestive tract. We also determined the dose that affects only fecundity. This suggests that normal growth of medaka in the wild does not mean the environment is free from microbead contamination. We are thus attempting to identify new biological indexes for monitoring the status of microbead contamination using our system.

The transfer of pollutants from chemical fertilizers through food webs within cropland is well documented; however, its impacts on the wild animals that forage on croplands but roost in other locations remain poorly understood. The potential for this cross-ecosystem ‘spillover’ of pollutants is greatest for bats, some of which exploit urban settlements as roosting niches but must travel long distances to reach croplands as foraging niches. Here, we used hairs from a colony of insectivorous bats, Chinese Noctule (Nyctalus plancyi), from an urban area in Southwest China to assess whether exposure to heavy metals/metalloids by the bats varied from 1975 to 2016. Historical changes occurred in hair cadmium (Cd) concentrations in adult females, which was exclusively explained by the regional fertilizer application intensity (FAI), even considering the potential impacts of Cd emissions in urban areas, as indicated by camphor trees (Cinnamomum camphora) near the bats' roosting niche, and the potential impacts of Cd in industrial wastewater, as documented in authorized databases. Therefore, the data from this bat colony, as urban dwellers, indicates Cd accumulation and cross-ecosystem transfer from rural croplands to an urban area.

The aim of this novel research was to determine the toxic burden of increased elements in water resources on the inhabitant wild animals (squirrels, turtles, bats), using particle induced x-ray emission (PIXE) and histopathological approaches. PIXE analysis of skin, muscle, lung, liver and kidney revealed significant increase in Al, Cl, Fe, Mg, Mn, Si and V. Moreover, data clearly reflect a significant (P < 0.001) deposition of toxic elements (Al, Cl, Fe and K) in the lung producing interstitial/proliferative pneumonitis, intra-alveolar hemorrhages, and thickening of alveolar capillary walls. The results obtained from the liver samples emphasized that majority of the animals were intoxicated with Cl, Mg, S, Si and V, which have produced profound deterioration and swelling of the hepatocytes. Likewise, histopathology of the kidney sections spotlighted severe nephritis and degenerative changes, which could be associated with the elevated amount of Al, Cl and Mg. This data undoubtedly provide relevant information on the heavy burden of toxic elements and their pathological outcomes in wild animals and highlight their potential risks for human exposure. Thus, the information provided is critical for developing effective strategies in dealing with health hazards associated with elemental exposures.

The micronucleus (MN) test of the human buccal mucosa was developed more than 30 years ago, although this technique has only recently been applied to wild mammals. This paper presents a pioneering study in the genotoxicological evaluation of the exfoliated cells of the buccal mucosa of bats. The assay was applied to two insectivorous bat species (Noctilio albiventris and Pteronotus parnellii) sampled in riparian corridors located in the city of Palmas (capital of the Brazilian state of Tocantins), with the results being compared with those obtained for a third insectivorous species (Nyctinomops laticaudatus), which has established a colony under a road bridge in the same region. This colony represents one of the largest molossidae populations ever recorded in Brazil. A significantly higher frequency of micronuclei was recorded in this colony, as well as a number of other nuclear abnormalities, including binucleated cells, cells with condensed chromatin and karyolysis, in comparison with the bats from the riparian corridors, indicating that the bats from the bridge colony are more susceptible to genotoxic damage. Thus, it is demonstrated the importance of the biomarker (MN) for use in wild animals and allows to conclude that colony bats are more susceptible to genotoxic damages.

Organophosphate flame retardants (PFRs) can be rapidly metabolized in the body, and recent studies have shown that the di-alkyl phosphates (DAPs) are important metabolites. The accumulation and distribution of 8 PFRs and their 4 DAPs metabolites were first investigated in whole-body samples and various tissues of three freshwater fish species (topmouth gudgeon, crucian carp and loach) with different feeding habits from locations around Beijing, China. Concentrations of ΣPFRs in whole-body samples across all sampling locations ranged from 264.7 to 1973 ng g−1 lipid weight (lw), while all the paired DAP metabolites were detected in the total range from 35.3 to 510 ng g−1 lw. The calculated log bioconcentration factors (BCFs) of PFRs in whole fish were correlated with their log KOW (P < 0.05). The metabolite/parent ratios (MPRs) of ΣDAPs were calculated and ranged from 0.10 to 1.12 in whole-fish of all species. The MPRs of BBOEP/TBOEP were the highest. With respect to their distribution in different tissues, both the parent PFRs and metabolites were found at relatively higher levels in the liver than in other tissues (muscle, intestine, kidney and ovary), which was markedly different from those observed in avian species in previous studies. The accumulation of PFRs and DAPs in various tissues was not significantly correlated with the lipid content. The highest PFRs level in the liver may be related to the active hepatic accumulation processes. Meanwhile, the MPRs for all 4 pairs were the highest in the kidney relative to the other tissues. To the best of our knowledge, this is the first study of DAPs in the wild animals, and our study may improve the understanding of the accumulation and metabolism of PFRs in the body.

Information on naturally occurring thyroid disease in wild animals in general and in small mammals specifically is extremely limited. In the present field-based work, we investigated the structure and function of thyroid glands of deer mice (Peromyscus maniculata) studied as sentinels of ecosystem sustainability on reclaimed areas post-mining on the oil sands of northeastern Alberta, because of their greater sensitivity to contaminants relative to meadow voles (Microtus pennsylvanicus) on the same sites. Extraction of bitumen in the oil sands of northeastern Alberta, results in the release of contaminants including polycyclic aromatic compounds (PACs), metals, and metalloids to the environment that have a measurable biological cost to wildlife living in the affected areas. In previous investigations, deer mice exposed to pollution at reclaimed areas showed compromised ability to regenerate glutathione indicating oxidative stress, together with decreased testicular mass and body condition during the breeding season. In the present study, thyroid glands from those deer mice from the reclaimed site had markedly increased follicular cell proliferation and decreased colloid compared to animals from the reference site. This pathology was positively associated with the greater oxidative stress in the deer mice. Thyroid hormones, both thyroxine and triiodothyronine, were also higher in animals with greater oxidative stress indicating increased metabolic demands from contaminant related subclinical toxicity. This work emphasizes the value of using a combination of endocrinological, histological and oxidative stress biomarkers to provide sensitive measures of contaminant exposure in small mammals on the oil sands.

Artificial light at night has been linked to a wide variety of physiological and behavioural consequences in humans and animals. Given that little is known about the impact of light pollution on sleep in wild animals, we tested how experimentally elevated light levels affected sleep behaviour of female songbirds rearing 10 day old chicks. Using a within-subject design, individual sleep behaviour was observed over three consecutive nights in great tits (Parus major), with females sleeping in a natural dark situation on the first and third night, whereas on the second night they were exposed to a light-emitting diode (1.6 lux). Artificial light in the nest box dramatically and significantly affected sleep behaviour, causing females to fall asleep later (95 min; while entry time was unaffected), wake up earlier (74 min) and sleep less (56%). Females spent a greater proportion of the night awake and the frequency of their sleep bouts decreased, while the length of their sleep bouts remained equal. Artificial light also increased begging of chicks at night, which may have contributed to the sleep disruption in females or vice versa. The night following the light treatment, females slept 25% more compared to the first night, which was mainly achieved by increasing the frequency of sleep bouts. Although there was a consistent pattern in how artificial light affected sleep, there was also large among-individual variation in how strongly females were affected. When comparing current results with a similar experiment during winter, our results highlight differences in effects between seasons and underscore the importance of studying light pollution during different seasons. Our study shows that light pollution may have a significant impact on sleep behaviour in free-living animals during the reproductive season, which may provide a potential mechanism by which artificial light affects fitness.