Puryear and Runstadler currently located at Cummings School of Veterinary Medicine at Tufts University, North Grafton, MA, USA

Abstract

Grey seals (Halichoerus grypus) are emerging as a suitable mammalian sentinel for the Northwest Atlantic marine nearshore ecosystem. By monitoring individual grey seals’ health, the data can provide insight into environmental changes and how those changes may affect ecosystem and human health. Gene expression assays have been used in other marine mammal species, both cetaceans and pinnipeds, with moderate success correlating results with health status in cetaceans.^1-4 The objective of this study is to establish gene expression as an informative health measurement in grey seals in the Northwest Atlantic. To date, this study 1) established gene expression of seven gene reference ranges to infer immunocompetence of individual grey seals; and 2) compared individual’s results to their hematology and biochemical test results. A total of forty-eight samples were collected from grey seals off Cape Cod in January 2016 (n=24) and 2017 (n=16), and pre-release rehabilitated grey seals from rehabilitation centers in New York and Massachusetts (n=8) between 2014 and 2017. The expression levels of seven genes were measured by using a real-time PCR quantification including: interleukin 2 (IL2), interleukin 4 (IL4), interleukin 8 (IL8), interleukin 10 (IL10), interferon gamma (IFNγ), SLAM CD150 (SLAM), and transforming growth factor beta (TGFβ). These genes were selected because they represent both inflammatory and non-inflammatory immune responses.^5-7 Gene expression reference ranges were calculated for each gene using descriptive statistics. One individual showed multiple gene expression values greater than two standard deviations above the mean concentrations for these genes. This individual’s hematology and chemistry values revealed a mild alkalosis, leukocytosis, and thrombocytosis consistent with the healing musculoskeletal injury noted at time of sampling. This study demonstrates potential for this technique to be used as part of a comprehensive health surveillance program. This work provides a new tool for understanding grey seal health, and their use as a sentinel species for the Northwest Atlantic marine near-shore ecosystem.

Acknowledgments

The authors would like to thank the Tufts Institute for the Environment and the Edward Gorey Charitable Trust for funding this work, the field teams for both Monomoy and Muskeget Islands and the Northwest Atlantic Seal Research Consortium.

* Presenting author
+ Student presenter

Literature Cited

1.  Sitt T, et al. 2008. Quantitation of leukocyte gene expression in cetaceans. Dev Comp Immunol. 32:1253–1259.

2.  Kakuschke A, et al. 2005. Immunological impact of metals in harbor seals (Phoca vitulina) of the North Sea. Environ Sci Technol. 39:7568–7575.

3.  Fonfara S, Siebert U, Prange A, Colijn F. 2007. The impact of stress on cytokine and haptoglobin mRNA expression in blood samples from harbor porpoises (Phocoena phocoena). J Mar Biol Assoc UK. 87:305.

4.  Lehnert K, et al. 2014. Molecular biomarkers in grey seals (Halichoerus grypus) to evaluate pollutant exposure, health and immune status. Mar Pollut Bull. 88:311–318.

5.  Sintes J, Engel P. 2011. SLAM (CD150) is a multitasking immunoreceptor: from cosignalling to bacterial recognition. Immunol Cell Biol. 89:161–163.

6.  Matsushima K. 2016. Essential inflammation involvement of interleukin-8 (IL-8) in acute inflammation. J Leukoc Biol. 56:559–564.

7.  Wheelock EF. 1965. Interferon-like virus inhibitor induced in human leukocytes by phytohemagglutinin. Science. 149:310–311.