Serum electrophoresis has been used as an immunology status marker in human medicine for a long time. It has also been performed on several marine mammals, including cetaceans and pinnipeds. Studies on serum electrophoresis in harbor seals is scarce though. Three groups of harbor seals were tested in this project: seals held permanently in captivity, rehabilitated seal pups (both Rehabilitation Center Friedrichskoog, Germany) and wild seals caught in the Wadden Sea of Schleswig-Holstein. Blood was taken during several years, centrifuged and serum was stored at -20°C before examination. The serum electrophoresis was done in collaboration with Westkuestenklinikum Heide, Germany. The densitograms of the animals held in captivity show very little differences even though the animals are of different ages and sex. Whereas in Hall (1998) differences in the serum chemistry of gray seals were clearly related to age and sex. The densitograms of the rehabilitated pups look similar to those of the animals held in captivity. The end of the graphs of the captive animals as well as of the wild catches show a distinct peak of a protein that cannot be found in the pups (nor humans or other mammals). It seems that an unknown stationary protein is present at the starting point of the electrophoresis. The analysis of the serum electrophoresis of the wild catches proved to be rather difficult, as--except for the last fraction (Albumin)--there were no distinct peaks visible. The actual contamination was most likely caused by lipemia, which is a common phenomenon in marine mammals such as harbor seals.3 In Davis et al. (2001) the high molecular weight of the apoE in pinnipeds, especially in harbor seals, is mentioned. It seems that the wild catches dispose a higher amount of lipoproteins, therefore also of apoE, that might interfere with the migration of the other serum proteins and blur the bands on the cellulose acetate. Why only the wild catches show this phenomenon is not clear yet. Ultracentrifugation may help solve this problem.
The authors are grateful to all the helpers who went out with us to catch the seals, the volunteers at the rehab center for their care of the affiliated pups and last but not least a big thanks to the seals who let us have their blood.
1. Davis R, VR Pierotti, SJ Lauer, ST Hubl, JW McLean, JL Witztum, SG Young (1991). Lipoproteins in pinnipeds: analysis of a high molecular weight form of apolipoprotein E. J. Lipid Res. 32: 1013-1023.
2. Hall A (1998). Blood chemistry and hematology of gray seal (Halichoerus grypus) pups from birth to postweaning. J. Zoo Wildl. Med. 29 (4): 401-407.
3. Tryland M, E Brun (2001). Serum chemistry of the minke whale from the northeastern Atlantic. J. Wildl. Dis. 37 (2): 332-341.