Maternal Transfer Of Specific Antibodies (IgM) In Zebrafish Danio Rerio

Maternal immunity is of paramount importance for protection of young ones at early stage of life since the immune factors of an immunocompetent female are transferred transplacentally or through colostrum or yolk to offspring. Both innate and adaptive types of factors are transferred from mother to offspring in fishes. These factors include lysozymes, complement factors, protease inhibitors, lectins, immunoglobulin ( IgM ). IgM is present in most teleost fishes. The maternally derived IgM usually persists for a limited duration, exhausts with the yolk absorption process, and completely disappears thereafter and is absent during the later larval stages. It is disputed whether the maternally derived IgM protects the embryos in present research. The main objectives of the present study were to purify IgM form serum and eggs in zebrafish (Danio rerio) and examine the specific activity of the maternally derived IgM.First part of the workdeals with the isolation, purification and characterization of IgM from serum and egg extracts of zebrafish. Protein A-sepharose colomn was used to isolate and purify of IgM. The purification process was optimized for zebrafish IgM, both from serum and egg extracts. Purified IgM was characterized by affinity chromatography and sodium dodecyl sulfate-polyacrylamide gels (SDS-PAGE) under reducing conditions. The protein peak in affinity chromatography corresponded with IgM. IgM treated with mercaptoethanol was dissociated and visualized on SDS-PAGE. The relative molecular mass of the IgM H chain is 83kDa in serum and 90 kDa in eggs.In contrast to the mammalian immune system, the development of the teleostean immune system occurs in the open environment. Oviparity necessitates a rapid ontogeny of the immune system. Danio rerio larvae cannot mount an adaptive immune response to potential pathogens and presumably must depend on innate responses. In the present study, the possibility of maternal transfer of antibodies to eggs was examined. Adult female zebrafish were injected four times at fortnight intervals with the hapten–carrier complex, trinitrophenylated bovine serum albumin (TNP-BSA). Compared to immunized and non-immunized serum and eggs, total protein of immunized zebrafishes was a little higher in serum and eggs. Western blot of eggs indicated a rise in maternal IgM after immunization, Thus immunization is good for IgM accumulation in eggs.The sera of immunized zebrafish demonstrated antibody activity to bovine serum albumin (BSA), TNP-BSA, and especially trinitrophenylated ovalbumin (TNP-OVA) when examined by enzyme-linked immunosorbent assay (ELISA). Reactivity to TNP-OVA confirmes that antibodies are produced against TNP. On analysis of eggs by ELISA, it was found that TNP-specific antibodies were present in the egg extracts. This demonstrated the transfer of IgM to eggs in Danio rerio.Zebrafishes was injected with TNP-BSA and hapen-specific antibodies from adult fishes were obtioned from the serum which contain polyclonal antibody particularly specific TNP binded antibody. These antibodis can transfer from mother to eggs, and had specific binding-activity with TNP-OVA but not with ovalbumin (OVA). Thus maternal transfer of specific antibody to eggs and proved. And then it has been hypothesized that the eggs are protected by the maternal IgM.Maternal transfer of immunity not only has its theoretical significance,but also has potential practical application in fish farming. A good deal of research has been devoted to increase fry immunity in yong larva by means of an increase in lectin, lysozyme or IgM in eggs.The paper provides practical evidence to the theoretical significance of improving survival rate of fry by immuning parents.