Molecular characterization and expression analysis of secretory immunoglobulin M (IgM) heavy chain gene in rohu, Labeo rohita

• Published in: Animal biotechnology Vol. 31; no. 5; pp. 413 - 425
• Main Authors: Saravanan, K., Rajendran, K. V., Gireesh-Babu, P., Purushothaman, C. S., Makesh, M.
• Format: Journal Article
• Language: English
• Published: England Taylor & Francis 11.09.2020; Taylor & Francis Ltd
• Subjects: adaptive immunity; Adaptive Immunity - genetics; Aeromonas hydrophila; Amino acid sequence; Amino acids; Animals; Chains; Conserved sequence; Cyprinidae - genetics; Cyprinidae - immunology; Domains; Gene expression; IgM heavy chain; Immune response; Immune response (humoral); Immune system; Immunoglobulin Heavy Chains - analysis; Immunoglobulin Heavy Chains - chemistry; Immunoglobulin Heavy Chains - genetics; Immunoglobulin Heavy Chains - metabolism; Immunoglobulin M; Immunoglobulin M - analysis; Immunoglobulin M - chemistry; Immunoglobulin M - genetics; Immunoglobulin M - metabolism; Immunoglobulins; Intestine; Kidney - chemistry; Kidneys; Labeo rohita; Lymphoid tissue; Models, Molecular; Organ Specificity; Phylogeny; Polypeptides; Protein sorting signals; Residues; Spleen; Three dimensional models; Tissue analysis; Tryptophan; Aeromonas hydrophila; IgM heavy chain; Labeo rohita; adaptive immunity; gene expression
• ISSN: 1049-5398; 1532-2378
• DOI: 10.1080/10495398.2019.1612411

Immunoglobulin M (IgM) is the major isotype among teleost immunoglobulins. The present study was aimed to explore IgM heavy chain gene and its expression profile in rohu. Full-length IgM heavy chain cDNA of rohu consisted of 1994 bp encoding a polypeptide of 576 amino acid residues including a leader peptide, variable (VH) and constant (CH1-CH2-CH3-CH4) domains confirming the secretory form of IgM. The sequence carries conserved residues such as cysteine, tryptophan and amino acid motifs like 'YYCAR' and 'FDYWGKGT-VTV-S'. The predicted 3 D model confirmed various domains of rohu IgM heavy chain. Phylogenetic tree analysis revealed that IgM heavy chain gene of rohu shared the same cluster with that of other cyprinid fishes. Tissue distribution analysis showed the predominant level of IgM heavy chain gene expression in kidney, spleen and intestine. IgM heavy chain gene expression in rohu kidney was found to be up-regulated and reached a maximum at 7 days post-challenge with Aeromonas hydrophila. These findings demonstrate the first report of full-length secretory IgM heavy chain gene in rohu. Besides, IgM heavy chain gene was highly expressed in major lymphoid tissues and bacterial challenge influenced its expression which further confirmed its role in the adaptive humoral immune response.