Proteinas

Fish & Shellfish Immunology (2008) 25, 181e187

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journal homepage: www.elsevier.com/locate/fsi

Isolation and characterisation of two antimicrobial
peptides from haemocytes of the American lobster
Homarus americanus
Andrea L. Battison a,*, Rachael Summerfield a, Aleksander Patrzykat b
a

Atlantic Veterinary College Lobster Science Centre, University ofPrince Edward Island, 550 University Avenue,
Charlottetown, Prince Edward Island, C1A 4P3, Canada
b
NRC Institute for Marine Biosciences/Institut des biosciences marines CNRC,
1411 Oxford Street, Halifax, Nova Scotia, B3H 3Z1, Canada
Received 21 December 2007; revised 31 March 2008; accepted 9 April 2008
Available online 16 April 2008

KEYWORDS
Lobster;
Hoa-crustin;
Antimicrobialpeptide;
Homarus americanus;
Haemocytes;
Homarin

Abstract Two antimicrobial peptides from haemocytes of the American lobster, Homarus
americanus H. Milne Edwards 1837, were isolated and partially characterised e the first such description for this species. CAP-2, an approximately 12 kDa peptide, contained amino acid sequences corresponding to the predicted sequence for Hoa-crustin. Crustins arewhey acidic
protein (WAP) domain - containing peptides isolated from crustacean haemocytes. CAP-2 did
not have any activity towards the Gram positive coccus Aerococcus viridans unlike carcinin,
a crustin from Carcinus maenas haemocytes, which may partially explain the lobster’s susceptibility to this bacterium. A second peptide, CAP-1, was a multimer composed of 4e6 kDa subunits withsimilarities to amphibian temporins. CAP-1 may represent a novel group of
antimicrobial peptides for marine invertebrates and has been tentatively named ‘homarin’. Homarin had bacteriostatic activity against some Gram negative bacteria and both protozoastatic
and protozoacidal activity against two cultured scuticociliate parasites Mesanophrys chesapeakensis and Anophryoides haemophila, the latter asignificant pathogen of H. americanus.
ª 2008 Elsevier Ltd. All rights reserved.

Introduction
Investigation into the antimicrobial properties of the
haemolymph of the American lobster, Homarus americanus

* Corresponding author. Tel.:þ1 902 894 2845; fax: þ1 902 894
2885.
E-mail address: abattison@upei.ca (A.L. Battison).

H. Milne Edwards 1837, began in the late 1960s and 1970s
[1e3]. Acton etal. [1] demonstrated increasing titres of
antibacterial activity in citrated haemolymph of lobsters
injected with formalin-killed bacteria. Stewart and Zwicker
[3] examined the antimicrobial properties of different
components of haemolymph (haemocytes, plasma, and
serum) separately and in combination. They determined
that serum, representing a combination of plasma and lysed
haemocytes,was the most effective component. This

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doi:10.1016/j.fsi.2008.04.005

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antibacterial activity was also inducible e injection of lobsters with killed bacteria caused a transient increase in activity of the plasma and serum, but not haemocyte lysates
[3]. While haemocytes were integral to the antimicrobial
activityof serum, the specific nature of this activity was
not determined. It is possible that some of this observed
activity could be attributed to antimicrobial peptides in
H. americanus haemocytes.
Antimicrobial peptides are small proteins, usually less
than 10 kDa, present in all types of plants, animals and prokaryotes [4,5]. Antimicrobial peptides are an integral component of the innate immunesystem. Present in most
tissues, particularly in secretions on epithelial surfaces
(e.g., respiratory, enteric, genitourinary, and cutaneous)
and in high concentrations in white blood cells and haemocytes, they provide an immediate defence against potential
pathogens. Production of antimicrobial peptides can be
constitutive or inducible [6]. Some peptides are cleavage
products of larger...