title: Alternative complement activity in the egg cytosol of amphioxus Branchiostoma belcheri: evidence for the defense role of maternal complement components.
abstract: BACKGROUND
  The eggs in most invertebrates are fertilized externally, and therefore their resulting embryos are exposed to an environment full of microbes, many of which are pathogens capable of killing other organisms. How the developing embryos of invertebrates defend themselves against pathogenic attacks is an intriguing question to biologists, and remains largely unknown.
  
  
  RESULTS
  Here we clearly demonstrated that the egg cytosol prepared from the newly fertilized eggs of amphioxus Branchiostoma belcheri, an invertebrate chordate, was able to inhibit the growth of both the Gram-negative bacterium Vibrio anguillarum and the Gram-positive bacterium Staphylococcus aureus. All findings point to that it is the complement system operating via the alternative pathway that is attributable to the bacteriostatic activity.
  
  
  CONCLUSIONS
  This appears to be the first report providing the evidence for the functional role of the maternal complement components in the eggs of invertebrate species, paving the way for the study of maternal immunity in other invertebrate organisms whose eggs are fertilized in vitro. It also supports the notion that the early developing embryos share some defense mechanisms common with the adult species.
authors.affiliation: Department of Marine Biology, Ocean University of China, Qingdao, People's Republic of China.
authors.forename: Yujun
authors.initials: Y
authors.lastname: Liang
authors.forename: Shicui
authors.initials: S
authors.lastname: Zhang
authors.forename: Zhiping
authors.initials: Z
authors.lastname: Wang
mesh_terms: D000818:Animals; D043344:Chordata / Q000378:metabolism*; D003167:Complement Activation; D003176:Complement C3 / Q000378:metabolism; D011415:Complement Factor B / Q000378:metabolism; D003165:Complement System Proteins / Q000378:metabolism; D003600:Cytosol / Q000276:immunology / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D007155:Immunologic Factors / Q000378:metabolism; D008954:Models, Biological; D010063:Ovum / Q000276:immunology / Q000378:metabolism / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000378:metabolism; D014733:Vibrio / Q000378:metabolism
chemical_list: D003176:Complement C3; D007155:Immunologic Factors; D003165:Complement System Proteins; D011415:Complement Factor B