Abstract
Medaka (Oryzias latipes) is an aquatic organism that is readily affected by endocrine disruptors. Furthermore, its quick maturation, minimal requirement for breeding facilities, and constancy of life cycle makes the medaka optimal for use as an experimental animal. Thus, it is used to monitor water pollution and to examine toxic substances. In this paper, we used rapid micro two-dimensional polyacrylamide gel electrophoresis (RM2D-PAGE), which advantageous method with small sample size and fast migration to analyze plasma proteins and to detect vitellogenin (VTG), the egg yolk protein precursor of individual medaka.
RM2D-PAGE results showed that an average of 30 protein spots was obtained from each individual and that females differ from males with a unique spot at pI 5.5 to 7.5, being about 115 to 200kDa. In addition, each spot was quantified and VTG was identified by Western blot. More than one VTG spot was detected in female plasma, and VTG consisted of three molecular species of about 110, 200 and 400kDa in the pI 5.5 to 8.0 region.
Medaka plasma protein analysis by RM2D-PAGE, made it possible to analyze of 0.2μL of plasma from individual medaka, which is impossible by other assays.
