Deok Chan Lee

Pathological characteristics of olive flounder Paralichthys olivaceus experimentally infected with Streptococcus parauberis

Pathological characteristics of olive flounder Paralichthys olivaceus experimentally infected with Streptococcus parauberis were studied. Various stressful conditions, aeration and netting stress in particular, led to induced mortality by S. parauberis. Netting stress-induced mortality was positively correlated to bacterial dose and stressful conditions. Inflammation of the heart and pericarditis was the major pathological change observed in olive flounder experimentally infected with S. parauberis. During the infected period, the number of bacteria in the infected olive flounder was recorded over time. S. parauberis remained in all fish organs tested, especially in the heart and brain.

Molecular characterization, expression and functional analysis of peptidoglycan recognition protein-SC2 from rock bream, Oplegnathus fasciatus

ABSTRACT Peptidoglycan recognition proteins are members of the family of pattern recognition receptors (PRRs), that play important roles in the recognition of peptidoglycan and various biological processes. In this study, we have characterized peptidoglycan recognition protein‐SC2 (PGRP‐SC2) in rock bream (Oplegnathus fasciatus) (RbPGRP‐SC2) and analysed its expression in various tissues after pathogen challenge. A sequence alignment revealed that the residues essential to zinc binding of the deduced protein were highly conserved among all the organisms. Phylogenetic analysis revealed that RbPGRP‐SC2 is most closely related to the large yellow croaker PGRP‐SC2. RbPGRP‐SC2 was ubiquitously expressed in all tissues analysed, predominantly distributed in muscle and skin. After challenge with microbial pathogens (Edwardsiella piscicida), Streptococcus iniae or red seabream iridovirus [RSIV]), RbPGRP‐SC2 was up‐regulated in all the tissues examined, especially in liver. We produced recombinant RbPGRP‐SC2 (rRbPGRP‐SC2) using an Escherichia coli expression system. The rRbPGRP‐SC2 had agglutination activity towards both Gram‐negative (E. piscicida) and Gram‐positive bacteria (S. iniae). In addition, rRbPGRP‐SC2 induced leukocyte apoptosis and promoted leukocyte phagocytosis. These results suggest that the RbPGRP‐SC2 plays an important role in the immune system and in maintaining cellular homeostasis of rock bream. HighlightsPeptidoglycan recognition protein‐SC2 from rock bream was identified and characterized.RbPGRP‐SC2 was highly expressed in muscle and skin of healthy rock bream.RbPGRP‐SC2 was up‐regulated in the fish infected with pathogens, especially in liver.rRbPGRP‐SC2 can agglutinate pathogens, induce leukocyte apoptosis, and promote phagocytosis of pathogens.

The first report of CD2 associated protein gene, in a teleost (Rock bream, Oplegnathus fasciatus): An investigation of the immune response upon infection with several pathogens

Abstract CD2 is expressed on the surfaces of virtually all T cells and natural killer (NK) cells. In mammals, the CD2 molecule is 50 kDa. The cytoplasmic tail of CD2 interacts with CD2‐associated protein (CD2AP), which plays an important role in mediating the trigger signal in outer magnetic pole cells. In this study, we identified CD2AP from rock bream and investigated its gene expression. The ORF of CD2AP (1950 bp) encodes 650 amino acids (aa). CD2AP has a Src homology 3 (SH3) domain. Quantitative real‐time PCR analysis revealed that CD2AP shows higher expression in the gills and skin. Under experimental challenge, CD2AP gene expression was increased as relative to the control after 7 days. This result will improve our understanding of blood vessels in teleost fish, and will provide a basis for the study of CD2‐related genes. HighlightsWe identified the CD2AP from leucocytes of rock bream.CD2AP has a Src homology 3 (SH3) domain that interact with CD2.CD2AP is expressed late in during pathogen infection.