Element Concentrations and Histopathology of Liver and Kidney in West Greenland Ringed Seals (Pusa hispida).

Ringed seals are consumed in Greenland and are therefore included as a key biomonitoring species with the focus on pollution exposure and health effects. Ringed seals in Central West Greenland (Qeqertarsuaq) and in North West Greenland (Qaanaaq) were analyzed for metal concentrations in the liver and histological changes in the liver and kidney. The mean liver concentration of mercury in Qaanaaq was 3.73 ± 5.01 µg/g ww (range: 0.28-23.29 µg/g ww), and the mean cadmium concentration was 7.80 ± 8.95 µg/g ww (range: 0.013-38.79 µg/g ww). For Qeqertarsuaq, the liver concentration of mercury was 1.78 ± 1.70 µg/g ww (range: 0.45-8.00 µg/g ww) and the mean cadmium concentration was 11.58 ± 6.32 µg/g ww (range: 0.11-25.45 µg/g ww). Age had a positive effect on the liver concentrations of metals, while no effect was found for sex or histological changes. The prevalence of histological changes in liver tissue decreased in the following order: random pattern mononuclear cell infiltration (92.1%), portal cell infiltration (68.4%), hepatic intracellular fat (18.4%), portal fibrosis (7.9%), focal hepatic fibrosis (7.9%), bile duct hyperplasia/fibrosis (7.9%) and lipid granuloma (2.6%). For kidney tissue, the prevalence of histological changes decreased in the following order: glomerular mesangial deposits (54.1%) > glomerular basement membrane thickening (45.9%) > THD (40%) > tubular hyaline casts (14.0%) > glomerular atrophy (13.5%) > dilated tubules (13.5%) > glomerular hyper-cellularity (10.8%) > mononuclear cell infiltrations (8.1%).

Comparative transcriptome and methylome of polar bears, giant and red pandas reveal diet-driven adaptive evolution.

Epigenetic regulation plays an important role in the evolution of species adaptations, yet little information is available on the epigenetic mechanisms underlying the adaptive evolution of bamboo-eating in both giant pandas (Ailuropoda melanoleuca) and red pandas (Ailurus fulgens). To investigate the potential contribution of epigenetic to the adaptive evolution of bamboo-eating in giant and red pandas, we performed hepatic comparative transcriptome and methylome analyses between bamboo-eating pandas and carnivorous polar bears (Ursus maritimus). We found that genes involved in carbohydrate, lipid, amino acid, and protein metabolism showed significant differences in methylation and expression levels between the two panda species and polar bears. Clustering analysis of gene expression revealed that giant pandas did not form a sister group with the more closely related polar bears, suggesting that the expression pattern of genes in livers of giant pandas and red pandas have evolved convergently driven by their similar diets. Compared to polar bears, some key genes involved in carbohydrate metabolism and biological oxidation and cholesterol synthesis showed hypomethylation and higher expression in giant and red pandas, while genes involved in fat digestion and absorption, fatty acid metabolism, lysine degradation, resistance to lipid peroxidation and detoxification showed hypermethylation and low expression. Our study elucidates the special nutrient utilization mechanism of giant pandas and red pandas and provides some insights into the molecular mechanism of their adaptive evolution of bamboo feeding. This has important implications for the breeding and conservation of giant pandas and red pandas.

Nontarget and suspect screening reveals the presence of multiple plastic related compounds in polar bear, killer whale, narwhal and long-finned pilot whale blubber from East Greenland.

The monitoring of legacy contaminants in sentinel northern marine mammals has revealed some of the highest concentrations globally. However, investigations into the presence of chemicals of emerging Arctic concern (CEACs) and other lesser-known chemicals are rarely conducted, if at all. Here, we used a nontarget/suspect approach to screen for thousands of different chemicals, including many CEACs and plastic-related compounds (PRCs) in blubber/adipose from killer whales (Orcinus orca), narwhals (Monodon monoceros), long-finned pilot whales (Globicephala melas), and polar bears (Ursus maritimus) in East Greenland. 138 compounds were tentatively identified mostly as PRCs, and four were confirmed using authentic standards: di(2-ethylhexyl) phthalate (DEHP), diethyl phthalate (DEP), di(2-propylheptyl) phthalate (DPHP), and one antioxidant (Irganox 1010). Three other PRCs, a nonylphenol isomer, 2,6-di-tert-butylphenol, and dioctyl sebacate, exhibited fragmentation patterns matching those in library databases. While phthalates were only above detection limits in some polar bear and narwhal, Irganox 1010, nonylphenol, and 2,6-di-tert-butylphenol were detected in >50% of all samples. This study represents the first application of a nontarget/suspect screening approach in Arctic cetaceans, leading to the identification of multiple PRCs in their blubber. Further nontarget analyses are warranted to comprehensively characterize the extent of CEAC and PRC contamination within Arctic marine food webs.

Climate change introduces threatened killer whale populations and conservation challenges to the Arctic.

The Arctic is the fastest-warming region on the planet, and the lengthening ice-free season is opening Arctic waters to sub-Arctic species such as the killer whale (Orcinus orca). As apex predators, killer whales can cause significant ecosystem-scale changes. Setting conservation priorities for killer whales and their Arctic prey species requires knowledge of their evolutionary history and demographic trajectory. Using whole-genome resequencing of 24 killer whales sampled in the northwest Atlantic, we first explored the population structure and demographic history of Arctic killer whales. To better understand the broader geographic relationship of these Arctic killer whales to other populations, we compared them to a globally sampled dataset. Finally, we assessed threats to Arctic killer whales due to anthropogenic harvest by reviewing the peer-reviewed and gray literature. We found that there are two highly genetically distinct, non-interbreeding populations of killer whales using the eastern Canadian Arctic. These populations appear to be as genetically different from each other as are ecotypes described elsewhere in the killer whale range; however, our data cannot speak to ecological differences between these populations. One population is newly identified as globally genetically distinct, and the second is genetically similar to individuals sampled from Greenland. The effective sizes of both populations recently declined, and both appear vulnerable to inbreeding and reduced adaptive potential. Our survey of human-caused mortalities suggests that harvest poses an ongoing threat to both populations. The dynamic Arctic environment complicates conservation and management efforts, with killer whales adding top-down pressure on Arctic food webs crucial to northern communities' social and economic well-being. While killer whales represent a conservation priority, they also complicate decisions surrounding wildlife conservation and resource management in the Arctic amid the effects of climate change.

Low hunting costs in an expensive marine mammal predator.

Many large terrestrial mammalian predators use energy-intensive, high-risk, high-gain strategies to pursue large, high-quality prey. However, similar-sized marine mammal predators with even higher field metabolic rates (FMRs) consistently target prey three to six orders of magnitude smaller than themselves. Here, we address the question of how these active and expensive marine mammal predators can gain sufficient energy from consistently targeting small prey during breath-hold dives. Using harbor porpoises as model organisms, we show that hunting small aquatic prey is energetically cheap (<20% increase in FMR) for these marine predators, but it requires them to spend a large proportion (>60%) of time foraging. We conclude that this grazing foraging strategy on small prey is viable for marine mammal predators despite their high FMR because they can hunt near continuously at low marginal expense. Consequently, cessation of foraging due to human disturbance comes at a high cost, as porpoises must maintain their high thermoregulation costs with a reduced energy intake.

Global mercury concentrations in biota: their use as a basis for a global biomonitoring framework.

An important provision of the Minamata Convention on Mercury is to monitor and evaluate the effectiveness of the adopted measures and its implementation. Here, we describe for the first time currently available biotic mercury (Hg) data on a global scale to improve the understanding of global efforts to reduce the impact of Hg pollution on people and the environment. Data from the peer-reviewed literature were compiled in the Global Biotic Mercury Synthesis (GBMS) database (>550,000 data points). These data provide a foundation for establishing a biomonitoring framework needed to track Hg concentrations in biota globally. We describe Hg exposure in the taxa identified by the Minamata Convention: fish, sea turtles, birds, and marine mammals. Based on the GBMS database, Hg concentrations are presented at relevant geographic scales for continents and oceanic basins. We identify some effective regional templates for monitoring methylmercury (MeHg) availability in the environment, but overall illustrate that there is a general lack of regional biomonitoring initiatives around the world, especially in Africa, Australia, Indo-Pacific, Middle East, and South Atlantic and Pacific Oceans. Temporal trend data for Hg in biota are generally limited. Ecologically sensitive sites (where biota have above average MeHg tissue concentrations) have been identified throughout the world. Efforts to model and quantify ecosystem sensitivity locally, regionally, and globally could help establish effective and efficient biomonitoring programs. We present a framework for a global Hg biomonitoring network that includes a three-step continental and oceanic approach to integrate existing biomonitoring efforts and prioritize filling regional data gaps linked with key Hg sources. We describe a standardized approach that builds on an evidence-based evaluation to assess the Minamata Convention's progress to reduce the impact of global Hg pollution on people and the environment.

Did algal toxin and Klebsiella infections cause the unexplained 2007 mass mortality event in Danish and Swedish marine mammals?

An unusual mass mortality event (MME) of harbour seals (Phoca vitulina) and harbour porpoises (Phocoena phocoena) occurred in Denmark and Sweden in June 2007. Prior to this incident, the region had experienced two MMEs in harbour seals caused by Phocine Distemper Virus (PDV) in 1988 and 2002. Although epidemiology and symptoms of the 2007 MME resembled PDV, none of the animals examined for PDV tested positive. Thus, it has been speculated that another - yet unknown - pathogen caused the June 2007 MME. To shed new light on the likely cause of death, we combine previously unpublished veterinary examinations of harbour seals with novel analyses of algal toxins and algal monitoring data. All harbour seals subject to pathological examination showed pneumonia, but were negative for PDV, influenza and coronavirus. Histological analyses revealed septicaemia in multiple animals, and six animals tested positive for Klebsiella pneumonia. Furthermore, we detected the algal Dinophysis toxin DTX-1b (1-115 ng g-1) in five seals subject to toxicology, representing the first time DTX-1b has been detected in marine vertebrates. However, no animals tested positive for both Klebsiella and toxins. Thus, while our relatively small sample size prevent firm conclusions on causative agents, we speculate that the unexplained MME may have been caused by a chance incidence of multiple pathogens acting in parallel in June 2007, including Dinophysis toxin and Klebsiella. Our study illustrates the complexity of wildlife MMEs and highlights the need for thorough sampling during and after MMEs, as well as additional research on and monitoring of DTX-1b and other algal toxins in the region.

Gene expression and trace elements in Greenlandic ringed seals (Pusa hispida).

Marine top predators such as ringed seals biomagnify environmental contaminants; and with the increasing human activities in the Arctic, ringed seals are exposed to biologically significant concentrations of trace elements resulting in reproductive impairment, immunosuppression, and neurological damages. Little is known about the molecular effects of heavy metals on these vulnerable apex predators suffering from a rapidly changing Arctic with significant loss of sea-ice. In the present study, concentrations of cadmium (Cd), mercury (Hg) and selenium (Se) were measured in liver of sixteen Greenlandic ringed seals (nine adults and seven subadults) together with molecular biomarkers involved in bio-transformation, oxidative stress, endocrine disruption and immune activity in blood and blubber. The concentrations of trace elements increased in the following order: Hg > Se > Cd with levels of mercury and selenium being highest in adults. Aryl hydrocarbon receptor nuclear translocator (ARNT), peroxisome proliferator activated receptor alpha (PPARα, estrogen receptor alpha (ESR1), thyroid hormone receptor alpha (TRα) and interleukin - 2 (IL-2) mRNA transcript levels were highest in blubber, while heat shock protein 70 (HSP70) and interleukin - 10 (IL-10) were significantly higher in blood. There were no significant correlations between the concentrations of trace elements and mRNA transcript levels suggesting that stressors other than the trace elements investigated are responsible for the changes in gene expression levels. Since Hg seems to increase in Greenlandic ringed seals, there is a need to re-enforce health monitoring of this ringed seal population.

Ship noise causes tagged harbour porpoises to change direction or dive deeper.

Shipping is the most pervasive source of marine noise pollution globally, yet its impact on sensitive fauna remains unclear. We tracked 10 harbour porpoises for 5-10 days to determine exposure and behavioural reactions to modelled broadband noise (10 Hz-20 kHz, VHF-weighted) from individual ships monitored by AIS. Porpoises spent a third of their time experiencing ship noise above ambient, to which they regularly reacted by moving away during daytime and diving deeper during night. However, even ships >2 km away (noise levels of 93 ± 14 dB re 1 µPa2) caused animals to react 5-9 % of the time (∼18.6 ships/day). Ships can thus influence the behaviour and habitat use of cetaceans over long distances, with worrying implications for fitness in coastal areas where anthropogenic noise from dense ship traffic repeatedly disrupt their natural behaviour.

Impact of Holocene environmental change on the evolutionary ecology of an Arctic top predator.

The Arctic is among the most climatically sensitive environments on Earth, and the disappearance of multiyear sea ice in the Arctic Ocean is predicted within decades. As apex predators, polar bears are sentinel species for addressing the impact of environmental variability on Arctic marine ecosystems. By integrating genomics, isotopic analysis, morphometrics, and ecological modeling, we investigate how Holocene environmental changes affected polar bears around Greenland. We uncover reductions in effective population size coinciding with increases in annual mean sea surface temperature, reduction in sea ice cover, declines in suitable habitat, and shifts in suitable habitat northward. Furthermore, we show that west and east Greenlandic polar bears are morphologically, and ecologically distinct, putatively driven by regional biotic and genetic differences. Together, we provide insights into the vulnerability of polar bears to environmental change and how the Arctic marine ecosystem plays a vital role in shaping the evolutionary and ecological trajectories of its inhabitants.

Varying Diet Composition Causes Striking Differences in Legacy and Emerging Contaminant Concentrations in Killer Whales across the North Atlantic.

Lipophilic persistent organic pollutants (POPs) tend to biomagnify in food chains, resulting in higher concentrations in species such as killer whales (Orcinus orca) feeding on marine mammals compared to those consuming fish. Advancements in dietary studies include the use of quantitative fatty acid signature analysis (QFASA) and differentiation of feeding habits within and between populations of North Atlantic (NA) killer whales. This comprehensive study assessed the concentrations of legacy and emerging POPs in 162 killer whales from across the NA. We report significantly higher mean levels of polychlorinated biphenyls (PCBs), organochlorine pesticides, and flame retardants in Western NA killer whales compared to those of Eastern NA conspecifics. Mean ∑PCBs ranged from ∼100 mg/kg lipid weight (lw) in the Western NA (Canadian Arctic, Eastern Canada) to ∼50 mg/kg lw in the mid-NA (Greenland, Iceland) to ∼10 mg/kg lw in the Eastern NA (Norway, Faroe Islands). The observed variations in contaminant levels were strongly correlated with diet composition across locations (inferred from QFASA), emphasizing that diet and not environmental variation in contaminant concentrations among locations is crucial in assessing contaminant-associated health risks in killer whales. These findings highlight the urgency for implementing enhanced measures to safely dispose of POP-contaminated waste, prevent further environmental contamination, and mitigate the release of newer and potentially harmful contaminants.

Diet, lifestyle and contaminants in three east Greenland Inuit municipalities.

Persistent organic pollutants (POP) are environmental contaminants transported over long distances to the Arctic where they biomagnify in marine mammals subsistence hunted by Inuit and may therefore affect human health. Marine mammals in east Greenland are known to have the highest POP concentrations in the circumpolar Arctic area. Due to high intake of marine mammals, east Greenlandic Inuit likewise have the highest POP body burdens across the Arctic. This cross-sectional study aims to investigate the levels of POP and metals in Inuit with a high intake of top predatory species including killer whales and polar bears. Study participants include 37 men and 21 women from Kulusuk, Tasiilaq and Ittoqqortoormiit during year 2013-2015. Lipophilic POP (11 organochlorine-pesticides, 14 polychlorinated-biphenyls (PCB), 10 polybrominated diphenyl ethers), polyunsaturated fatty acids (PFUA) and cotinine were determined in plasma. Fifteen perfluoroalkylated substances (PFAS) were measured in serum and urine and the renal clearance was estimated. Finally the concentration of 10 metals were measured in whole blood. The median age was 38 years, Ittoqqortoormiit Inuit being the oldest. The smoking rate was around 70%, and Kulusuk participants had the lowest PFUA concentrations. Significant municipality differences were observed for lipophilic POP, serum PFAS, mercury, arsenic and selenium with highest concentrations in Ittoqqortoormiit Inuit. Males had higher blood concentrations of PFAS and lead. The estimated PFAS renal clearance and ratio of urine to serum were significantly higher for females, suggesting a sex difference in excretion via the kidney, maybe partly because men had higher serum PFAS concentrations. We observed that Inuit with intake of >200 g polar bear per week had significantly higher levels of PCB, PFAS, arsenic and selenium. In summary, the level of blood POP and heavy metals seems to relate to sex and the frequency intake of meat from marine mammals.

An evolutionarily distinct ringed seal in the Ilulissat Icefjord.

The Earth's polar regions are low rates of inter- and intraspecific diversification. An extreme mammalian example is the Arctic ringed seal (Pusa hispida hispida), which is assumed to be panmictic across its circumpolar Arctic range. Yet, local Inuit communities in Greenland and Canada recognize several regional variants; a finding supported by scientific studies of body size variation. It is however unclear whether this phenotypic variation reflects plasticity, morphs or distinct ecotypes. Here, we combine genomic, biologging and survey data, to document the existence of a unique ringed seal ecotype in the Ilulissat Icefjord (locally 'Kangia'), Greenland; a UNESCO World Heritage site, which is home to the most productive marine-terminating glacier in the Arctic. Genomic analyses reveal a divergence of Kangia ringed seals from other Arctic ringed seals about 240 kya, followed by secondary contact since the Last Glacial Maximum. Despite ongoing gene flow, multiple genomic regions appear under strong selection in Kangia ringed seals, including candidate genes associated with pelage coloration, growth and osmoregulation, potentially explaining the Kangia seal's phenotypic and behavioural uniqueness. The description of 'hidden' diversity and adaptations in yet another Arctic species merits a reassessment of the evolutionary processes that have shaped Arctic diversity and the traditional view of this region as an evolutionary freezer. Our study highlights the value of indigenous knowledge in guiding science and calls for efforts to identify distinct populations or ecotypes to understand how these might respond differently to environmental change.

Assessment of exposure to perfluorinated industrial substances and risk of immune suppression in Greenland and its global context: a mixed-methods study.

BACKGROUND: Perfluoroalkyl substances (PFASs) are ubiquitous global contaminants that do not readily biodegrade and are therefore routinely found worldwide in wildlife, humans, and the environment. There is a paucity of global assessments to understand regional and continental differences in exposure to PFASs and the associated health risks, including those for Indigenous Arctic communities who consume high trophic marine diets. We aimed to estimate the long-term exposure of dietary PFASs from consumption of polar bear and ringed seal meat and establish its association with blood serum concentrations of PFASs in Inuit in Ittoqoortoormiit (Scoresby Sound), East Greenland. We also aimed to assess the risk of immune suppression on the basis of European Food Safety Authority (EFSA) thresholds for weekly intake and blood serum concentrations of PFASs. Last, we conducted a worldwide risk assessment based on blood concentrations of PFASs emphasising Arctic exposure in a global context. METHODS: In this mixed-methods study, we conducted interviews to compare dietary exposure of PFASs in anonymous, non-pregnant, Inuit adults (aged ≥18 years) from full-time or part-time hunter families in Ittoqoortoormiit, East Greenland with ESFA toxic threshold values for tolerable weekly intake of the four most immunotoxic PFASs (∑4PFAS; perfluorooctanoic acid, perfluorononanoic acid, perfluorohexanesulfonic acid, and perfluorooctane sulfonate). Independent hospital staff from the local hospital randomly selected participants using simple randomisation using a telephone directory. Blood serum concentrations were then compared with EFSA risk categories: low (0·7-9·5 ng/mL), moderate (>9·5-17·5 ng/mL), high (>17·5-31·9 ng/mL), and severe (>31·9 ng/mL). We also reviewed the available scientific literature of ∑4PFAS concentrations in human blood to place the Inuit dataset in a broader global context. FINDINGS: Between Sept 21, and Oct 2, 2015, 22 participants were enrolled in the study, of which 12 were male and ten were female. Sex data were obtained from personal social security numbers and options were male or female. As a result of a subsistence diet high in marine mammal muscle, 322 (92%) of 350 people in the Ittoqoortoormiit cohort exceeded the established immunotoxic thresholds of ∑4PFASs set by EFSA's tolerable weekly intake of 4·4 ng/kg, and 301 (86%) were in the most severe risk category (>31·9 ng/mL) based on blood serum concentrations. This Inuit cohort had the highest non-occupational long-term exposure to PFASs worldwide despite their remote location relative to industrial sources. Using country-wide average values across global studies, we found that blood serum concentrations of PFASs in populations from European countries, North America, the Arctic, and Australia were generally higher than those in South America, Africa, and mainland Asia, with the highest concentrations found in people from USA, Canada, Greenland, Faroe Islands, Denmark, Iceland, Norway, Sweden, the UK, Spain, Poland, and Australia. These high exposure countries all fall within the EFSA moderate-risk and high-risk categories. INTERPRETATION: PFAS contamination of the environment and human populations occurs worldwide. This pollution not only poses substantial risks for immune system adverse events but also cardiovascular, cancerous, and reproductive endpoints. Data on such PFAS exposure is scarce in numerous countries. Therefore, it is important to also map out the exposure in these countries to enable a thorough global assessment of exposure and risks. FUNDING: Danish Cooperation for Environment in the Arctic.

Divergent migration routes reveal contrasting energy-minimization strategies to deal with differing resource predictability.

BACKGROUND: Seasonal long-distance movements are a common feature in many taxa allowing animals to deal with seasonal habitats and life-history demands. Many species use different strategies to prioritize time- or energy-minimization, sometimes employing stop-over behaviours to offset the physiological burden of the directed movement associated with migratory behaviour. Migratory strategies are often limited by life-history and environmental constraints, but can also be modulated by the predictability of resources en route. While theory on population-wide strategies (e.g. energy-minimization) are well studied, there are increasing evidence for individual-level variation in movement patterns indicative of finer scale differences in migration strategies. METHODS: We aimed to explore sources of individual variation in migration strategies for long-distance migrators using satellite telemetry location data from 41 narwhal spanning a 21-year period. Specifically, we aimed to determine and define the long-distance movement strategies adopted and how environmental variables may modulate these movements. Fine-scale movement behaviours were characterized using move-persistence models, where changes in move-persistence, highlighting autocorrelation in a movement trajectory, were evaluated against potential modulating environmental covariates. Areas of low move-persistence, indicative of area-restricted search-type behaviours, were deemed to indicate evidence of stop-overs along the migratory route. RESULTS: Here, we demonstrate two divergent migratory tactics to maintain a similar overall energy-minimization strategy within a single population of narwhal. Narwhal migrating offshore exhibited more tortuous movement trajectories overall with no evidence of spatially-consistent stop-over locations across individuals. Nearshore migrating narwhal undertook more directed routes, contrasted by spatially-explicit stop-over behaviour in highly-productive fjord and canyon systems along the coast of Baffin Island for periods of several days to several weeks. CONCLUSIONS: Within a single population, divergent migratory tactics can achieve a similar overall energy-minimizing strategy within a species as a response to differing trade-offs between predictable and unpredictable resources. Our methodological approach, which revealed the modulators of fine-scale migratory movements and predicted regional stop-over sites, is widely applicable to a variety of other aquatic and terrestrial species. Quantifying marine migration strategies will be key for adaptive conservation in the face of climate change and ever increasing human pressures.

Deep learning-based method for segmenting epithelial layer of tubules in histopathological images of testicular tissue.

Purpose: There is growing concern that male reproduction is affected by environmental chemicals. One way to determine the adverse effect of environmental pollutants is to use wild animals as monitors and evaluate testicular toxicity using histopathology. We propose an automated method to process histology images of testicular tissue. Approach: Testicular tissue consists of seminiferous tubules. Segmenting the epithelial layer of the seminiferous tubule is a prerequisite for developing automated methods to detect abnormalities in tissue. We suggest an encoder-decoder fully connected convolutional neural network model to segment the epithelial layer of the seminiferous tubules in histological images. The ResNet-34 is used in the feature encoder module, and the squeeze and excitation attention block is integrated into the encoding module improving the segmentation and localization of epithelium. Results: We applied the proposed method for the two-class problem, where the epithelial layer of the tubule is the target class. The F -score and Intersection over Union of the proposed method are 0.85 and 0.92. Although the proposed method is trained on a limited training set, it performs well on an independent dataset and outperforms other state-of-the-art methods. Conclusion: The pretrained ResNet-34 in the encoder and attention block suggested in the decoder result in better segmentation and generalization. The proposed method can be applied to testicular tissue images from any mammalian species and can be used as the first part of a fully automated testicular tissue processing pipeline. The dataset and codes are publicly available on GitHub.

Deep learning-based method for segmenting epithelial layer of tubules in histopathological images of testicular tissue.

Purpose: There is growing concern that male reproduction is affected by environmental chemicals. One way to determine the adverse effect of environmental pollutants is to use wild animals as monitors and evaluate testicular toxicity using histopathology. We propose an automated method to process histology images of testicular tissue. Approach: Testicular tissue consists of seminiferous tubules. Segmenting the epithelial layer of the seminiferous tubule is a prerequisite for developing automated methods to detect abnormalities in tissue. We suggest an encoder-decoder fully connected convolutional neural network model to segment the epithelial layer of the seminiferous tubules in histological images. The ResNet-34 is used in the feature encoder module, and the squeeze and excitation attention block is integrated into the encoding module improving the segmentation and localization of epithelium. Results: We applied the proposed method for the two-class problem, where the epithelial layer of the tubule is the target class. The F-score and Intersection over Union of the proposed method are 0.85 and 0.92. Although the proposed method is trained on a limited training set, it performs well on an independent dataset and outperforms other state-of-the-art methods. Conclusion: The pretrained ResNet-34 in the encoder and attention block suggested in the decoder result in better segmentation and generalization. The proposed method can be applied to testicular tissue images from any mammalian species and can be used as the first part of a fully automated testicular tissue processing pipeline. The dataset and codes are publicly available on GitHub.

The metabolome of pink-footed goose: Heavy metals and lipid metabolism.

Wildlife is exposed to mixtures of environmental contaminants that affect health and population dynamics. Exposure to toxic heavy metals originating from anthropogenic sources may exert metabolic effects at even low exposure concentrations. Here we investigated the relationships between heavy metal exposure and metabolic changes in the migratory bird pink-footed goose (Anser brachyrhynchus). We used blood pellet and blood plasma samples from 27 free-ranging pink-footed geese to study heavy metal (Cd, Cr, Hg, and Pb) exposure in relation to the metabolome. The results relate blood concentrations of Cd (range: 0.218-1.09 ng/g), Cr (range: 0.299-5.60 ng/g), and Hg (range: 2.63-6.00 ng/g) to signal areas of fatty acids and other lipids, while no correlations were identified for Pb level (range: 21.0-64.2 ng/g) exposure. Lipid signal areas were negatively associated with concentrations of Cr and positively associated with Hg exposure (both p < 0.05). α-Linolenic acid and 9-oxononanoic acid were negatively correlated to Cr exposure (both p < 0.05) and were related in the α-linolenic acid metabolism pathway. Compared to known thresholds for aviary species, the heavy metal concentrations are below levels of toxicity, which may explain the low number of metabolites that significantly change. Nevertheless, the heavy metal exposure is still correlated to changes in the lipid metabolism that may reduce migrating birds' breeding success and increase mortality for an exposed part of the population.

Erratum: Publisher's note: Deep learning-based method for segmenting epithelial layer of tubules in histopathological images of testicular tissue.

[This corrects the article DOI: 10.1117/1.JMI.10.3.037501.].