Difference between revisions of "Marine mammals' health as an indicator of ecosystem health - tools for monitoring"
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− | The following immune system parameters can be measured in blood samples of captive and wild living animals using biomolecular and biochemical methods[[Image:Kakuschke_2.jpg|thumb|right|'''Figure 2''':Overview of immunological investigations using blood samples of marine mammals.]]( | + | The following immune system parameters can be measured in blood samples of captive and wild living animals using biomolecular and biochemical methods[[Image:Kakuschke_2.jpg|thumb|right|'''Figure 2''':Overview of immunological investigations using blood samples of marine mammals.]](Fig. 2, Fig. 3): lymphocyte proliferation as important immune cell function, and the expression of cytokines released by immune cells, which participate in an immune reaction.[[Image:Kakuschke_3.jpg|thumb|left|'''Figure 3''': Directly after arrival in the Seal Station the lymphocytes of newborns were particularly susceptible to the toxic effect of metals. A lot of metals tested e.g. beryllium, lead and cadmium inhibit the lymphocyte proliferation (value <0.1). This effect decreased during the time of rehabilitation.]] |
===Technique for measurement of lymphocyte proliferation=== | ===Technique for measurement of lymphocyte proliferation=== |
Revision as of 15:43, 29 January 2013
Contents
Introduction
Marine mammals, are used as indicators of ecosystem change (Trilateral Monitoring and Assessment Program, TMAP, Fig. 1). They are top predators in the marine food web. Increasing industrial and commercial activity, e.g. fisheries and offshore drilling and wind parks, as well as the input of pollutants, affect the North Sea and Baltic Sea ecosystems, including native marine mammals such as Harbour Porpoises (Phocoena phocoena), Harbour Seals (Phoca vitulina) and Grey Seals (Halichoerus grypus). This article presents some tools for early diagnosis of the health status of Harbour Seals. The selected biomarkers are non-destructive and are parameters for the immune system, which plays a central role in the control of disease processes. The dysregulation of the immune system may lead to immune suppression or enhancement (hypersensitivity). The indicators for the effects of pollutants are identified and chemically characterised.Methodology
The following immune system parameters can be measured in blood samples of captive and wild living animals using biomolecular and biochemical methods(Fig. 2, Fig. 3): lymphocyte proliferation as important immune cell function, and the expression of cytokines released by immune cells, which participate in an immune reaction.Technique for measurement of lymphocyte proliferation
Lymphocytes are isolated from the blood sample and cultured with and without stimulation using a lymphocyte transformation test (LTT, Fig. 2). After incubation, transformation and proliferation are examined and a stimulation index is calculated.
Technique for quantification of cytokine expression
Cytokine expression is measured by analysing the amount of mRNA with the real time reverse transcriptase polymerase chain reaction (RT-PCR, Fig. 2). Detecting the amount of the mRNA allows us to calculate ratios between cytokines and thus establish the main focus of the immune response. Investigations of the cytokine expression pattern (Interleukin-1, -2, -4, -6, -10, -12, TNF, TGFß) allow the status of the immune reaction to be differentiated, whether the emphasis is on the cellular or humoral (body liquid) immune response.
Metal pollution – effects on immune system
Pollution with metals may affect the immuno-competence of free-ranging populations of marine mammals in many areas of the industrialised world. An imbalance of the immune system caused by pollutants has been suggested to play a role in the incidence of infectious diseases in marine mammals (Jepson et al., 1999[1]; Siebert et al., 1999[2]; Bennett et al., 2001[3]). Metals affect the function of immuno-competent cells by a variety of mechanisms. Depending on the particular metal, its speciation, concentration and bioavailability, and a number of other factors, a continuous metal exposure will result in immuno-suppression or immuno-stimulating effects.
- Metal induced hypersensitivity in seals
The chronic intake of metal pollutants makes marine mammals susceptible to developing hypersensitivity reactions. Metal-specific hypersensitivity reactions were found in different pinnipeds from the North Sea (Kakuschke, 2006[4]). The frequency of sensitising metals was in the order Mo > Ni >Ti > Cr, Al > Pb, Be, Sn. A relationship was found between the blood levels of metals to metalspecific hypersensitivity reactions (Kakuschke et al., 2005[5]). A relationship between lymphocyte proliferation and cytokine expression could be shown: in a study of a grey seal, a hypersensitivity reaction to Ni and Be has been correlated to alterations in the cytokine pattern (Kakuschke et al., 2006[6]).
- High susceptibility of the immune system of pups to the toxic effect of metals
Pups are exposed to metals due to the transplacental transfer mother/fetus, the transfer through the milk and later by contaminated prey. Kakuschke et al. (2007[7]) found that lymphocytes of seal pups are particularly susceptible to the toxic effects of metals in the newborn period and that this susceptibility decreases subsequently (Fig. 3).
Stress – effects on the immune system
The cytokine expression can be modulated by numerous factors, including stress. Fonfara et al. (2007[8]) compared cytokine mRNA expression from harbour porpoises exposed to different environments. Blood samples were taken from two healthy porpoises living in captivity at the Fjord and Belt Centre Kerteminde, Denmark, and from four wild porpoises accidentally caught in Danish waters. The results are suggestive of stress-induced modulation of the immune responses in the accidentally caught animals (Fig. 4).
Challenges
Anthropogenic influences lead to changes of the health status of the animals. A set of reliable medical parameters enables us to investigate routinely a higher number of animals and to obtain information at population level. This information is part of the assessment of the status of the ecosystem as required by the TMAP.
See also
Internal links
- Elemental mass spectrometry - a tool for monitoring trace element contaminants in the marine environment
- Acoustic monitoring of marine mammals
- Using biomarkers for the assessment of marine pollutions
References
- ↑ Jepson, P. D., Bennett, P. M., Allchin, C. R., Law, R. J., Kuiken, T., Baker, J. R., Rogan, E. & Kirkwood, J. K. (1999). Investigating potential associations between chronic exposure to polychlorinated biphenyls and infectious disease mortality in harbour porpoises from England and Wales. Science of the Total Environment, 244, 339-348.
- ↑ Siebert, U., Joiris, C., Holsbeek, L., Benke, H., Failing, K., Frese, K. & Petzinger, E. (1999). Potential relation between mercury concentrations and necropsy findings in cetaceans from German waters of the North and Baltic Seas. Marine Pollution Bulletin, 38 (4), 285-295.
- ↑ Bennett, P. M., Jepson, P. D., Law, R. J., Jones, B. R., Kuiken, T., Baker, J. R., Rogan, E. & Kirkwood, J. K. (2001). Exposure to heavy metals and infectious disease mortality in harbour porpoises from England and Wales. Environmental Pollution, 112 (1), 33-40.
- ↑ Kakuschke, A. (2006). Einfluss von Metallen auf das Immunsystem von Meeressäugern. Dissertation, Universität Hamburg.
- ↑ Kakuschke, A., Valentine-Thon, E., Griesel, S., Fonfara, S., Siebert, U. & Prange, A. (2005). The immunological impact of metals in Harbor Seals (Phoca vitulina) of the North Sea. Environmental Science & Technology, 39 (19), 7568-7575.
- ↑ Kakuschke, A., Valentine-Thon, E., Fonfara, S., Griesel, S., Siebert, U. & Prange, A. (2006). Metal sensitivity of marine mammals: a case study of a gray seal. Marine Mammal Science, 22 (4), 985-997.
- ↑ Kakuschke, A., Valentine-Thon, E., Fonfara, S., Griesel, S., Siebert, U. & Prange, A. (2008). Metal-Induced Impairment of the Cellular Immunity of Newborn Harbor Seals (Phoca Vitulina). Archives of Environmental Contamination and Toxicology,55 (1), 129-136. doi: 10.1007/s00244-007-9092-3
- ↑ Fonfara S., Siebert, U. Prange, A. & Colijn, F. (2007). The impact of stress on cytokine and Haptoglobin mRNA expression in blood samples from harbour porpoises (Phoconea phocoena). Journal of the Marine Biological Association of the United Kingdom, 87, 305-311.
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