Enhanced non-invasive respiratory sampling from bottlenose dolphins for breath metabolomics measurements

Climate change and cetacean health: impacts and future directions

Climate change directly impacts the foraging opportunities of cetaceans (e.g. lower prey availability), leads to habitat loss, and forces cetaceans to move to other feeding grounds. The rise in ocean temperature, low prey availability and loss of habitat can have severe consequences for cetacean survival, particularly those species that are already threatened or those with a limited habitat range. In addition, it is predicted that the concentration of contaminants in aquatic environments will increase owing to Arctic meltwater and increased rainfall events leading to higher rates of land-based runoff in downstream coastal areas. These persistent and mobile contaminants can bioaccumulate in the ecosystem, and lead to ecotoxicity with potentially severe consequences on the reproductive organs, immune system and metabolism of marine mammals. There is a need to measure and assess the cumulative impact of multiple stressors, given that climate change, habitat alteration, low prey availability and contaminants do not act in isolation. Human-caused perturbations to cetacean foraging abilities are becoming a pervasive and prevalent threat to many cetacean species on top of climate change-associated stressors. We need to move to a greater understanding of how multiple stressors impact the metabolism of cetaceans and ultimately their population trajectory. This article is part of the theme issue 'Nurturing resilient marine ecosystems'.

Untargeted plasma metabolomic analysis of wild bottlenose dolphins (Tursiops truncatus) indicate protein degradation when in poorer health

Cumulative exposure to sub-lethal anthropogenic stressors can affect the health and reproduction of coastal cetaceans and hence their population viability. To date, we do not have a clear understanding of the notion of health for cetaceans in an ecological context; that is, how health status affects the ability of individuals to survive and reproduce. Here, we make use of a unique health-monitoring programme of estuarine bottlenose dolphins in South Carolina and Florida to determine de novo changes in biological pathways, using untargeted plasma metabolomics, depending on the health status of individuals obtained from veterinary screening. We found that individuals that were in a poor health state had lower circulating amino acids pointing towards increased involvement of gluconeogenesis (i.e., new formation of glucose). More mechanistic work is needed to disentangle the interconnection between health and energy metabolism in cetaceans to mediate potential metabolic constraints they may face during periods of stress.

Metabolomics on the study of marine organisms

BACKGROUND

Marine ecosystems are hosts to a vast array of organisms, being among the most richly biodiverse locations on the planet. The study of these ecosystems is very important, as they are not only a significant source of food for the world but also have, in recent years, become a prolific source of compounds with therapeutic potential. Studies of aspects of marine life have involved diverse fields of marine science, and the use of metabolomics as an experimental approach has increased in recent years. As part of the "omics" technologies, metabolomics has been used to deepen the understanding of interactions between marine organisms and their environment at a metabolic level and to discover new metabolites produced by these organisms.

AIM OF REVIEW

This review provides an overview of the use of metabolomics in the study of marine organisms. It also explores the use of metabolomics tools common to other fields such as plants and human metabolomics that could potentially contribute to marine organism studies. It deals with the entire process of a metabolomic study, from sample collection considerations, metabolite extraction, analytical techniques, and data analysis. It also includes an overview of recent applications of metabolomics in fields such as marine ecology and drug discovery and future perspectives of its use in the study of marine organisms.

KEY SCIENTIFIC CONCEPTS OF REVIEW

The review covers all the steps involved in metabolomic studies of marine organisms including, collection, extraction methods, analytical tools, statistical analysis, and dereplication. It aims to provide insight into all aspects that a newcomer to the field should consider when undertaking marine metabolomics.

Breathomics: Review of Sample Collection and Analysis, Data Modeling and Clinical Applications

Metabolomics research is rapidly gaining momentum in disease diagnosis, on top of other Omics technologies. Breathomics, as a branch of metabolomics is developing in various frontiers, for early and noninvasive monitoring of disease. This review starts with a brief introduction to metabolomics and breathomics. A number of important technical issues in exhaled breath collection and factors affecting the sampling procedures are presented. We review the recent progress in metabolomics approaches and a summary of their applications on the respiratory and non-respiratory diseases investigated by breath analysis. Recent reports on breathomics studies retrieved from Scopus and Pubmed were reviewed in this work. We conclude that analyzing breath metabolites (both volatile and nonvolatile) is valuable in disease diagnoses, and therefore believe that breathomics will turn into a promising noninvasive discipline in biomarker discovery and early disease detection in personalized medicine. The problem of wide variations in the reported metabolite concentrations from breathomics studies should be tackled by developing more accurate analytical methods and sophisticated numerical analytical alogorithms.

1H NMR metabolomic analysis of skin and blubber of bottlenose dolphins reveals a functional metabolic dichotomy

The common bottlenose dolphin (Tursiops truncatus) is a carnivorous cetacean that thrives in marine environments, one of the apex predators of the marine food web. They are found in coastal and estuarine ecosystems, which are known to be sensitive to environmental impacts. Dolphins are considered sentinel organisms for monitoring the health of coastal marine ecosystems due to their role as predators that can bioaccumulate contaminants. Although recent studies have focused on capturing the circulating metabolomes of these mammals, and in the context of pollutants and exposures in the marine environment, skin and blubber are important surface and protective tissues that have not been adequately probed for metabolism. Using a proton nuclear magnetic resonance spectroscopy (¹H NMR) based metabolomics approach, we quantified 51 metabolites belonging to 74 different metabolic pathways in the skin and blubber of stranded bottlenose dolphin (n = 4) samples collected at different localities in the Southern Zone coast of Yucatan Peninsula of Mexico. Results indicate that metabolism of skin and blubber are quantitatively very different. These metabolite abundances could help discriminate the tissue-types using supervised partial least square regression discriminant analysis (PLSDA). Further, using hierarchical clustering analysis and random forest analysis of the metabolite abundances, the results pointed to unique metabolites that are important classifiers of the tissue-type. On one hand, the differential metabolic patterns, mainly linking fatty acid metabolism and ketogenic amino acids, seem to constitute a characteristic of blubber, thus pointing to fat synthesis and deposition. On the other hand, the skin showed several metabolites involved in gluconeogenic pathways, pointing towards an active anabolic energy-generating metabolism. The most notable pathways found in both tissues included: urea cycle, nucleotide metabolism, amino acid metabolism, glutathione metabolism among others. Our ¹H NMR metabolomics analysis allowed the quantification of metabolites associated with these two organs, i.e., pyruvic acid, arginine, ornithine, 2-hydroxybutyric acid, 3-hydroxyisobutyric acid, and acetic acid, as discriminatory and classifying metabolites. These results would lead to further understanding of the functional and physiological roles of dolphin skin and blubber metabolism for better efforts in their conservation, as well as useful target biopsy tissues for monitoring of dolphin health conditions in marine pollution and ecotoxicology studies.

Power-efficient self-cleaning hydrophilic condenser surface for portable exhaled breath condensate (EBC) metabolomic sampling

In this work, we present a hydrophilic self-cleaning condenser surface for the collection of biological and environmental aerosol samples. The condenser is installed in a battery-operated hand-held breath sampling device. The device performance is characterized by the collection and analysis of exhaled breath samples from a group of volunteers. The exhaled breath condensate is collected on a subcooled condenser surface, transferred into a storage vial, and its chemical content is analyzed using mass spectrometric methods. The engineered surface supports upon it a continuous condensation cycle, and this allows the collection of liquid samples exceeding the saturation mass/area limit of a plain hydrophilic surface. The condenser surface employs two constituent parameters: a low surface energy barrier to enhance nucleation and condensation efficiency, and a network of surface microstructures to create a self-cleaning mechanism for fluid aggregation into a reservoir. Removal of the liquid condensate from the condenser surface prevents the formation of a thick liquid layer, and thus maintains a continuous condensation cycle with a minimum decrease in heat transfer efficiency as condensation occurs on the surface. The self-cleaning condenser surfaces may have a number of applications in the collection of biological, chemical, or environmental aerosol samples. Sample phase conversion to liquid can facilitate sample manipulation and chemical analysis of matrices with low concentrations. Here, we demonstrate the use of a self-cleaning microcondenser for the collection of exhaled breath condensate with a hand-held portable device. All breath collections with the two devices were performed with the same group of volunteers under UC Davis IRB protocol 63701-3.

New Technologies for Monitoring Marine Mammal Health

Omics technologies have been developed in recent decades and applied to different subjects, although the greatest advancements have been achieved in human biology and disease. Genome sequencing and the exploration of its coding and noncoding regions are rapidly yielding meaningful answers to diverse questions, relating genome information to protein activity to environmental changes. In the past, marine mammal genetic and transcriptional studies have been restricted due to the lack of reference genomes. But the advance of high-throughput sequencing is revolutionizing the life sciences technologies. As long-lived organisms, at the top of the food chain, marine mammals play an important role in marine ecosystems and while their protected status is in favor of conservation of the species, it also complicates the researcher's approach to traditional measurements of health. Omics data generated by high-throughput technologies will represent an important key for improving the scientific basis for understanding both marine mammal and environment health.

Exhaled breath condensate methods adapted from human studies using longitudinal metabolomics for predicting early health alterations in dolphins

Monitoring health conditions is essential to detect early asymptomatic stages of a disease. To achieve this, blood, urine and breath samples are commonly used as a routine clinical diagnostic. These samples offer the opportunity to detect specific metabolites related to diseases and provide a better understanding of their development. Although blood samples are commonly used routinely to monitor health, the implementation of a relatively noninvasive technique, such as exhaled breath condensate (EBC) analysis, may further benefit the well-being of both humans and other animals. EBC analysis can be used to track possible physical or biochemical alterations caused by common diseases of the bottlenose dolphin (Tursiops truncatus), such as infections or inflammatory-mediated processes. We have used an untargeted metabolomic method with liquid chromatography-mass spectrometry analysis of EBC samples to determine biomarkers related to disease development. In this study, five dolphins under human care were followed up for 1 year. We collected paired blood, physical examination information, and EBC samples. We then statistically correlated this information to predict specific health alterations. Three dolphins provided promising case study information about biomarkers related to cutaneous infections, respiratory infections, dental disease, or hormonal changes (pregnancy). The use of complementary liquid chromatography platforms, with hydrophilic interaction chromatography and reverse-phased columns, allowed us to detect a wide spectrum of EBC biomarker compounds that could be related to these health alterations. Moreover, these two analytical techniques not only provided complementary metabolite information but in both cases they also provided promising diagnostic information for these health conditions. Graphical abstract Collection of the exhaled condensed breath from a bottlenose dolphin from U.S. Navy Marine Mammal Program (MMP).

Noninvasive Respiratory Metabolite Analysis Associated with Clinical Disease in Cetaceans: A Deepwater Horizon Oil Spill Study

Health assessments of wild cetaceans can be challenging due to the difficulty of gaining access to conventional diagnostic matrices of blood, serum and others. While the noninvasive detection of metabolites in exhaled breath could potentially help to address this problem, there exists a knowledge gap regarding associations between known disease states and breath metabolite profiles in cetaceans. This technology was applied to the largest marine oil spill in U.S. history (The 2010 Deepwater Horizon oil spill in the Gulf of Mexico). An accurate analysis was performed to test for associations between the exhaled breath metabolome and sonographic lung abnormalities as well as hematological, serum biochemical, and endocrine hormone parameters. Importantly, metabolites consistent with chronic inflammation, such as products of lung epithelial cellular breakdown and arachidonic acid cascade metabolites were associated with sonographic evidence of lung consolidation. Exhaled breath condensate (EBC) metabolite profiles also correlated with serum hormone concentrations (cortisol and aldosterone), hepatobiliary enzyme levels, white blood cell counts, and iron homeostasis. The correlations among breath metabolites and conventional health measures suggest potential application of breath sampling for remotely assessing health of wild cetaceans. This methodology may hold promise for large cetaceans in the wild for which routine collection of blood and respiratory anomalies are not currently feasible.

Human breath metabolomics using an optimized non-invasive exhaled breath condensate sampler

Exhaled breath condensate (EBC) analysis is a developing field with tremendous promise to advance personalized, non-invasive health diagnostics as new analytical instrumentation platforms and detection methods are developed. Multiple commercially-available and researcher-built experimental samplers are reported in the literature. However, there is very limited information available to determine an effective breath sampling approach, especially regarding the dependence of breath sample metabolomic content on the collection device design and sampling methodology. This lack of an optimal standard procedure results in a range of reported results that are sometimes contradictory. Here, we present a design of a portable human EBC sampler optimized for collection and preservation of the rich metabolomic content of breath. The performance of the engineered device is compared to two commercially available breath collection devices: the RTube^™ and TurboDECCS. A number of design and performance parameters are considered, including: condenser temperature stability during sampling, collection efficiency, condenser material choice, and saliva contamination in the collected breath samples. The significance of the biological content of breath samples, collected with each device, is evaluated with a set of mass spectrometry methods and was the primary factor for evaluating device performance. The design includes an adjustable mass-size threshold for aerodynamic filtering of saliva droplets from the breath flow. Engineering an inexpensive device that allows efficient collection of metalomic-rich breath samples is intended to aid further advancement in the field of breath analysis for non-invasive health diagnostic. EBC sampling from human volunteers was performed under UC Davis IRB protocol 63701-3 (09/30/2014-07/07/2017).