Three isotypes of immunoglobulin light chains in large yellow croaker, Pseudosciaena crocea: Molecular cloning, characterization, and expression analysis

Both cDNA library mining and transcriptome analysis were used to obtain 21 immunoglobulin light chain (IgL) sequences for the large yellow croaker, Pseudosciaena crocea. Full-length cDNA sequences are available for 10 of these, and they were identified as belonging to the three IgL isotypes of LycIgL1, LycIgL2, and LycIgL3. The LycIgL1 isotype is most abundant in the large yellow croaker IgL repertoire, as in the other teleosts. Tissue expression profile analysis revealed that the three LycIgL isotypes were constitutively expressed at different abundances in the kidney, spleen, liver, gill, heart, intestine, and muscle, although the heart did not express LycIgL3. Real-time polymerase chain reaction revealed that expression of the three LycIgL isotypes in the kidney and spleen tissues was up-regulated during 72 h of inductions with poly(I:C) or bacterial vaccine at different intensities and in different manners. The LycIgL1 isotype responded to stimulations most intensely in the spleen, while the LycIgL3 isotype responded most quickly in the kidney. Compared to the LycIgL1 and LycIgL3 isotypes, the LycIgL2 isotype responded more slowly and weakly in both tissues. These results indicate different isotypes of LycIgL respond to immune stimuli in the spleen and kidney in an isotypic-specific manner.