title: Isolation and Purification of an Antibacterial Protein from Immune Induced Haemolymph of American Cockroach,Periplaneta americana.
abstract: BACKGROUND
  Antimicrobial peptides play a role as effectors substances in the immunity of vertebrate and invertebrate hosts. In the current study, antimicrobial peptide was isolated from the haemolymph of the American cockroach,Periplaneta americana.
  
  
  METHODS
  Micrococcus luteusas Gram-positive bacteria andEscherichia colias Gram-negative bacteria were candidate for injection. Induction was done by injecting both bacteria into the abdominal cavity of two groups of cockroaches separately. The haemolymphs were collected 24 hours after post injection and initially tested against both bacteria. Subsequently, the immune induced haemolymph was purified by high performance liquid chromatography (HPLC) to separate the proteins responsible for the antibacterial activity.
  
  
  RESULTS
  The non-induced haemolymph did not show any activity against both bacteria whereas induced haemolymph exhibited high activity againstM. luteusbut did less againstE. coli. Two fractions showed antibacterial activity againstM. luteus.Finally the molecular weight of the isolated antibacterial proteins were determined as 72 kDa and 62 kDa using SDS-PAGE.
  
  
  CONCLUSIONS
  Induced haemolymph of American cockroaches has the ability to produce peptides to combat against Gram-positive bacteria when an immune challenge is mounted. Further work has to be done to sequence of the protein, which it would be advantageous.
authors.affiliation: Department of Medical Entomology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Hamid Reza
authors.initials: HR
authors.lastname: Basseri
authors.affiliation: Department of Biology, Payame Noor University, Tehran, Iran.
authors.forename: Amir
authors.initials: A
authors.lastname: Dadi-Khoeni
authors.affiliation: Department of Photobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Ronak
authors.initials: R
authors.lastname: Bakhtiari
authors.affiliation: Department of Medical Entomology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Mandan
authors.initials: M
authors.lastname: Abolhassani
authors.affiliation: Department of Biology, Payame Noor University, Tehran, Iran.
authors.forename: Reza
authors.initials: R
authors.lastname: Hajihosseini-Baghdadabadi
keywords: American cockroach; Antibacterial protein; Escherichia coli; Isolation; Micrococcus luteus