Identification of squalamine in the plasma membrane of white blood cells in the sea lamprey, Petromyzon marinus

Sang-Seon Yun and Weiming Li

Department of Fisheries and Wildlife, Michigan State University, East Lansing, MI 48824

Corresponding Author: liweim{at}msu.edu

It is well established that innate mechanisms play an important role in the immunity of fish. Antimicrobial peptides have been isolated and characterized from several species of teleosts. Here, we report the isolation of an antimicrobial compound from the blood of bacterially-challenged sea lamprey, Petromyzon marinus. An acetic acid extract from the blood cells of challenged fish was subjected to solid phase extraction, cation-exchange chromatography, gel filtration chromatography and reversed phase high performance liquid chromatography, with the purified fractions assayed for antimicrobial activity. Surprisingly, antimicrobial activity in these fractions originated from squalamine, an aminosterol previously identified in the dogfish shark, Squalus acanthias. Further chromatographic and mass spectrometry analyses confirmed the identity of squalamine, an anti-microbial and anti-angiogenic agent in the active fraction from the sea lamprey blood cells. Immunocytochemical analysis localized squalamine to the plasma membrane of white blood cells. We therefore postulate that squalamine has an important role in the innate immunity that defends the lamprey against microbial invasion. The full biochemical and immunological roles of squalamine in the white blood cell membrane remain to be investigated.

Add to CiteULike CiteULike Add to Complore Complore Add to Connotea Connotea Add to Del.icio.us Del.icio.us Add to Digg Digg Add to Reddit Reddit Add to Technorati Technorati What's this?