title: First molecular cloning and characterisation of caspase-9 gene in fish and its involvement in a gram negative septicaemia.
abstract: Caspase-9 is an initiator caspase in the apoptotic process whose function is to activate effector caspases that are downstream in the mitochondrial pathway of apoptosis. This work reports for the first time the complete sequencing and characterisation of caspase-9 in fish. A 1924bp cDNA of sea bass caspase-9 was obtained, consisting of 1308bp open reading frame coding for 435 amino acids, 199bp of the 5'-UTR and 417bp of the 3'-UTR including a canonical polyadenilation signal 10 nucleotides upstream the polyadenilation tail. The sequence retains the pentapeptide active-site motif (QACGG) and the putative cleavage sites at Asp(121), Asp(325) and Asp(343). The sequence of sea bass caspase-9 exhibits a very close homology to the sequences of caspase-9 from other vertebrates, particularly with the putative caspases-9 of Danio rerio and Tetraodon nigroviridis (77.5 and 75.4% similarity, respectively), justifying the fact that the phylogenetic analysis groups these species together with sea bass. The sea bass caspase-9 gene exists as a single copy gene and is organised in 9 introns and 10 exons. The sea bass caspase-9 showed a basal expression in all the organs analysed, although weaker in spleen. The expression of sea bass caspase-9 in the head kidney of sea bass infected with the Photobacterium damselae ssp. piscicida (Phdp) strain PP3, showed increased expression from 0 to 12h returning to control levels at 24h. Caspase-9 activity was detected in Phdp infected sea bass head kidney from 18 to 48h post-infection, when the fish were with advanced septicaemia.
authors.affiliation: Fish Immunology and Vaccinology, IBMC-Instituto de Biologia Molecular e Celular, R. do Campo Alegre 823, 4150-180 Porto, Portugal.
authors.forename: Marta I R
authors.initials: MI
authors.lastname: Reis
authors.forename: Ana
authors.initials: A
authors.lastname: do Vale
authors.forename: Cristina
authors.initials: C
authors.lastname: Pinto
authors.forename: Diana S
authors.initials: DS
authors.lastname: Nascimento
authors.forename: Carolina
authors.initials: C
authors.lastname: Costa-Ramos
authors.forename: Daniela S P
authors.initials: DS
authors.lastname: Silva
authors.forename: Manuel T
authors.initials: MT
authors.lastname: Silva
authors.forename: Nuno M S
authors.initials: NM
authors.lastname: Dos Santos
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016470:Bacteremia / Q000235:genetics / Q000662:veterinary*; D001483:Base Sequence; D001492:Bass / Q000235:genetics* / Q000382:microbiology; D053453:Caspase 9 / Q000737:chemistry / Q000145:classification / Q000235:genetics*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D005393:Fish Diseases / Q000201:enzymology / Q000235:genetics / Q000382:microbiology*; D015870:Gene Expression; D016905:Gram-Negative Bacterial Infections / Q000201:enzymology / Q000235:genetics / Q000662:veterinary*; D008969:Molecular Sequence Data; D010776:Photobacterium; D010802:Phylogeny; D017386:Sequence Homology, Amino Acid
chemical_list: D018076:DNA, Complementary; D053453:Caspase 9