Abstract
Populations of eiders in Alaska have been in a state of decline since the 1970's.1 Many studies have looked for a possible explanation for the decline. Some researchers have proposed that predation and extreme weather conditions in conjunction with the slow reproduction rates and late maturation of this species are the main culprits. Others, however, have proposed that the source is a metabolic constraint, such as infectious bursal disease. Little is known about the immune systems of these birds. Given the importance of the immune system to survival and health and the fact that perturbations in the immune system may provide indications of stress within a population, a closer look at the eider immune system may shed some light on the plight that these birds are facing.
To provide some insight into the humoral immune system of the eider, several steps were executed. First, immunoglobulin G (IgG) was isolated from the yolks of 14 spectacled eider eggs (infertile or from abandoned nests), which were provided by the Alaska SeaLife Center (Seward, AK). Egg yolk extraction was chosen not only because it is a noninvasive method, but also because large amounts of antibody are stored in the yolk. SDS-PAGE tests of the extracted yolk showed that eider IgG is present. The heavy chain band was located at approximately 64kD, the light chain band at approximately 23KD, and a potential truncated heavy chain band at approximately 40kD. In Grabar-Williams, Ouchterlony, ELISA, and western blot tests, commercially available anti-chicken IgG has been shown to have binding affinity for the isolated immunoglobulin. Subsequently, the IgG in the extracted yolk samples was further purified using an affinity column coupled with purchased anti-chicken IgG.
The purified IgG also was used as an immunogen in mice to initiate the production of hybridomas that will produce monoclonal antibodies specific for eider IgG. Currently, these hybridomas are being screened to see whether any are producing the desired anti-eider IgG antibody. Once positively producing hybridomas are obtained, characterization of the produced monoclonal antibodies will be performed using the same immunochemical techniques as mentioned above. When this characterization is complete, the species-specific antibodies can be used in ELISAs to measure immunoglobulin levels not only in the eider egg yolks but also in adult serum samples.
References
1. Stehn RA, Dau CP, Conant B, WI Butler Jr. 1993. Decline of spectacled eiders nesting in western Alaska. Arctic 46: 264-277.