RESUMEN
In this study, the complementary (c)DNA sequence encoding orange-spotted grouper Epinephelus coioides Tak1 (ectak1) was cloned, which has an open reading frame of 1728 bp that encodes 575 amino acids (aa). Sequence analysis indicated that Ectak1 contains two characteristic conserved domains, i.e. an N-terminal serine-threonine protein kinase catalytic domain (27-275 aa) and a C-terminal coiled-coil region (499-562 aa). Ectak1 shares high sequence identity with Tak1 from other fish species, especially those of Nile tilapia Oreochromis niloticus (96%) and zebra mbuna Maylandia zebra (96%). ectak1 transcripts were expressed broadly in all of the tissues tested, but ectak1 expression was reduced mainly in the local infection sites (skin and gill) after infection with Cryptocaryon irritans. Intracellular localization analysis showed that Ectak1 was distributed mainly in the cytoplasm. A luciferase reporter assay showed that Ectak1 significantly impaired the NF-κB activity induced by E. coioides Myd88 and Traf6. Overall, these results suggest that Ectak1 functions to reduce the activity of NF-κB induced by toll-like receptor (TLR) signal molecules in HEK-293T cells, and it might have an important role in host defences against parasitic infections.
RESUMEN
Cryptocaryon irritans is one of the most important ectoparasites of marine fish. To identify the potential role of immune-related genes in antiparasitic immune responses in fish, we monitored the expression change of IL-8, COX-2, C-type lectin and transferrin in local and systemic immune organs of orange-spotted grouper post-C. irritans infection. IL-8 expression was up-regulated during the course of infection in the skin, while COX-2 and transferrin expression was up-regulated in the gill. COX-2 expression was significantly down-regulated in the spleen (0·7-5% of its control) and head kidney (0·5-4% of its control) post-primary infection. Transferrin expression was also down-regulated in the spleen and head kidney from 6 h to 5 days post-primary infection. However, C-type lectin expression was up-regulated in all tested organs post-infection, with the exception of day 7 in the spleen post-primary infection where the expression level was slightly down-regulated (44% of its control). These results suggest that these four immune-related genes play an important role in grouper anti-C. irritans infection and that local immune organs as the active organs contribute more than systemic immune organs to this course.
