Applications of Omics Approaches to Decipher the Impact of Contaminants in Dolphins

*Reyna Cristina Collí-Dulá and Ixchel Mariel Ruiz-Hernández*

### **Abstract**

With the advent of omic technologies (genomic, transcriptomic, proteomic, metabolomic and lipidomic), it has been possible to identify global profiles of genes, proteins or metabolites in cells, tissues or organ systems at the same time. Key pathways can be identified associated with certain diseases, physiology processes or adverse effects in response to contaminants in marine organisms. This review focuses on underlining how the use of omics technology in dolphins has contributed to understanding its physiological responses and ambient stressors. They provide a basis for understanding dolphins' physiology and a means for monitoring health conditions as well as furthering ecotoxicology studies.

**Keywords:** omics technologies, contamination, dolphin

### **1. Introduction**

One of the concerns in environmental matters is the continuous discharge of countless numbers of chemicals derived from human activities into aquatic systems. These include a large number of contaminants, among these commercial and industrial products (e.g., metals, industrial additives, surfactants and pesticides), personal care products, pharmaceuticals and endocrine-disrupting compounds, among others [1]. The presence of relevant concentrations in the environment has dramatic consequences to the organisms that inhabit these systems (e.g., affecting reproduction and survival), which is reflected in the decline of their populations and accumulation of pollutants [2].

A major concern about contaminants in aquatic systems is the bioaccumulation and biomagnification that can result with all organisms present in these systems including harmful effects to human health [3, 4]. Mammalian organisms, especially dolphins, are considered sentinel species for monitoring the health of coastal marine ecosystems [5, 6]. The main reason for that is (1) they are at the highest trophic level of the food chain and due to their role as predators, they can bioaccumulate contaminants, and (2) they also can live for longer periods (more than 40 years). It makes them good organisms to show long-term accumulation characteristics from contaminants like heavy metals in the marine environment [7]. Recently, with the development of new technologies within the "omic sciences" such as genomics,

transcriptomics, proteomics and metabolomics, great advances have been made in the biological science disciplines, particularly in human health. In environmental areas "omics" have begun to have a large impact [8], mainly in aquatic toxicology [9, 10]. Together, new genomic sequencing and postgenomic technologies make it possible to obtain detailed information on drugs, toxicants, pollutants, nutrients and physical and psychological stressors on an omic scale [11]. The use of these omic technologies has allowed the emergence of ecotoxicogenomic disciplines [12, 13].

With these technologies, it is possible to determine the effect of a particular event in the life of a cell, organ or organism in response to contaminants. Through the characterization of the transcriptome, proteome or metabolome, one can perform global analysis to determinate transcriptional/proteomic or metabolomic changes at the same time in many samples (cells, tissues, biofluids, etc.) and be able to make the comparison among them. Omics technologies in environmental matters can help to assess the health statuses of aquatic systems, understand the mechanisms of action of the contaminants, through profiling of genes, proteins or metabolites that may enrich key pathways (molecular or biochemical). It sheds light on how dolphins respond to contaminants while helping to predict adverse effects on other marine organisms (**Figure 1**). This review highlights the

#### **Figure 1.**

*Integration of omics technologies in marine organisms.*

*Applications of Omics Approaches to Decipher the Impact of Contaminants in Dolphins DOI: http://dx.doi.org/10.5772/intechopen.102424*

**Figure 2.**

*Number of studies related with omics approach in dolphin.*

omics studies performed on dolphins to gather information regarding contamination levels and their effects on worldwide dolphin populations (**Figure 2**). Applications of the omics approach help to understand the dolphins' physiology as a way to monitor dolphin health conditions and to further ecotoxicology studies. Conclusively, it might provide a method for developing regulations for chemical discharge as well as management and conservation strategies for these kinds of ecosystems.

The three major omics technologies that have proven to have a tremendous impact include transcriptomics, proteomics and metabolomics [14].

### **2. Selection of bibliographic material**

We reviewed relevantly and recently published studies on the applicability and usefulness of Omics in dolphins. The selection of scientific publications was made through the use of search engines from Google Scholar, PubMed and Scopus to locate studies of interest using the keywords "transcriptomic", "proteomic", "metabolomic", "lipidomic" and "dolphin". We excluded all repeated studies. It was inevitable that some omics research was bot captured due to them not included the keywords we used. For the selection of publications, only the research studies that were related to contaminants were included in the data set (**Table 1**).

Based on these criteria, 59 publications were selected from >250 reviewed. Transcriptomics was the most frequently applied technique (38%) followed by proteomics (30%), metabolomics (21%) and finally, lipidomic (10.2%). In general searching the omic studies selected, we identified 8 topics including "contamination", "physiology" and "health" among others based on the type of research described in the publications. More details about each topic are given in **Figure 3**. Contamination studies were dominant using the transcriptomic method (31%), compared to studies focusing on proteomics (0%), metabolomics (8%) and lipidomics (0%). We noticed that proteomics and lipidomics are less used in studies related to contamination. However, proteomics is the most frequent technology applied to identifying responses associated with the physiology of dolphins (28%), followed by lipidomics (33%),



*Applications of Omics Approaches to Decipher the Impact of Contaminants in Dolphins DOI: http://dx.doi.org/10.5772/intechopen.102424*

**Table 1.**

 *Depict of the most relevant transcriptomic, proteomic and metabolomic studies performed in dolphin in response to the contaminants.*

**Figure 3.** *Status of studies of omics in dolphins.*

metabolomics (25%), and transcriptomics (13%). With respect to studies related to health, metabolomic tools (34%) were predominant, followed by transcriptomics (26%) and proteomics (11%). Interestingly, we noticed that the number of studies selected in omics and dolphins does not show an increase over time as we expected, it was diverse (**Figure 1**). After 2016, the selected literature showed an increase in the application of omics in dolphin research, notably, most studies focused on using metabolomics (LC/MS) and transcriptomic high throughput RNA sequencing (RNA-seq) tools as a diagnostic method for the detection of contaminants in oil spills and with contaminants of emerging concern (CECs). In general, it seems that there is a trend toward the increased use of transcriptomics, with studies dominating the literature from 2018 to 2019, and lipidomic applications from 2020 to 2021.
