Big Defensins, a Diverse Family of Antimicrobial Peptides That Follows Different Patterns of Expression in Hemocytes of the Oyster Crassostrea gigas
Figure 2
Big defensins form a group predominantly present in mollusk species and closer to vertebrate defensins.
a: Multiple alignments of mature polypeptides of big defensins from bivalve mollusks, horseshoe crab and amphioxus. Identical amino acid residues are shaded with black backgrounds. b: Phylogenetic tree of different defensin groups, including big defensins, CSαβ-containing defensins, α-defensins, β-defensins and β-defensin-like peptides from fish. The tree was constructed using the Neighbour-Joining method in MEGA 4. Bootstrap sampling was reiterated 1,000 times. Sequences included in analyses of defensins were the following, where asterisks (*) indicate mollusk big defensin members newly identified in this study from GenBank: (i) big defensins: oysters Crassostrea gigas (Cg-BigDef1*: AEE92768, Cg-BigDef2*: AEE92775, Cg-BigDef3*: AEE92778) and C. virginica (BDEF_CRAVI*: CV133156), horseshoe crabs Tachypleus tridentatus (BDEF_TACTR: P80957) and Carcinoscorpius rotundicauda (BDEF_CARRO: CK086629), amphioxus Branchiostoma belcheri tsingtauense (BDEF_BRABE: AAO18674) and B. floridae (BDEF_BRAFL: ADH03419), scallops Argopecten irradians (AiBD: ABC61319) and Mizuhopecten yessoensis (MyBD: GH736001), clams Venerupis (Ruditapes) philippinarum (VpBD: ADM25826, VpBD-EST*: AM873974) and Mercenaria mercenaria (BDEF_MERME: GO915266), mussels Mytilus galloprovincialis (BDEF_MYTGA*: FL490131), M. californianus (BDEF1_MYTCA*: GE761911, BDEF2_MYTCA*: GE759807) and Bathymodiolus azoricus (BDEF_BATAZ: HM756150), abalone Haliotis diversicolor (BDEF_HALDV*: GT870909); (ii) CSαβ-containing defensins: oysters C. gigas (Cg-Defm: CAJ19280, Cg-Defh1: ABD66301, Cg-Defh2: ABD66302) and C. virginica (AOD: P85008), mussels M. edulis (DEFA_MYTED: P81610, DEFB_MYTED: P81611) and M. galloprovincialis (MGD-1: P80571, MGD-2: AAD52660), abalones Haliotis discus discus (DEF_HALDS: ACZ15982) and H. discus hannai (DEF_HALHA: ABF69125), scorpion Androctonus australis (DEF4_ANDAU: P56686), tick Dermacentor variabilis (VSNA1: AAO24323), fruit fly Drosophila melanogaster (DEFI_DROME: P36192), mosquitos Anopheles gambiae (DEFI_ANOGA: Q17027) and Aedes aegypi (DEFC_AEDAE: P81603), saprophytic fungus Pseudoplectania nigrella (PLECT_PSENR: Q53I06); (iii) α-defensins: rhesus monkey Macaca mulatta (DEF1_MACMU: P60030), house mouse Mus musculus (CRYP-1: NP_034161), Norway rat Rattus norvegicus (DEF2_RAT: Q62715), rabbit Oryctolagus cuniculus (DEF3_RABIT: P01376), domestic guinea pig Cavia porcellus (DEF1A_CAVPO: P11478), Homo sapiens (HNP-1: NP_004075, HNP-3: AAA35753, HNP-4: NP_001916); (iv) β-defensins: spiny lobster Panulirus japonicus (PJD1: ACM62357, PJD2: ACM62358), chicken Gallus gallus (GAL4: NP_001001610), wild turkey Meleagris gallopavo (GPV-1: AAG09213), R. norvegicus (RBD-4: NP_071989), water buffalo Bubalus bubalis (DEFB_BUBBU: ABI36600); cattle Bos taurus (DEFB_BOSTA: CAC15400), goat Capra hircus (DEFB_CAPHI: ABF71365), H. sapiens (HBD-2: NP_004933, HBD-3: NP_061131); (v) fish defensins: rainbow trout Oncorhynchus mykiss (DEF_ONCMY: ABR68250), zebrafish Danio rerio (DEF_DANRE: AM181358), fugu pufferfish Takifugu rubripes (DEF_TATRU: CAJ57646), spotted green pufferfish Tetraodon nigroviridis (DEF_TATNI: CAJ57644), Japanese flounder Paralichthys olivaceus (DEF_PAROL: ADA84138).