RAG-1 and IgM genes, markers for early development of the immune system in the gadoid haddock, Melanogrammus aeglefinus, L.

Y. Corripio-Miyar, S. Bird, J. W. Treasurer, C. J. Secombes

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The full sequence of the heavy chain of Immunoglobulin M (IgM) and a partial fragment of the recombination activating gene-1 (RAG-1) gene were sequenced in haddock, Melanogrammus aeglefinus, L. The complete transcript of haddock IgM consisted of 1865 bp and translated into a 572-aa peptide. The RAG-1 fragment was 1776 bp and was identified as the core region of RAG-1. These two immune genes were used in expression studies as markers of early development in haddock larvae. A DIG labelled oligoprobe of the RAG-1 gene was used in whole-mount in situ hybridisation (WISH). A hybridisation signal for RAG-1 was first detected in larvae at 25 days post-hatching (dph) in two bilateral symmetric regions of the head identified as the thymus. Further expression studies were carried out by RT-PCR analysis of RAG-1 and IgM on larval samples obtained during early development, i.e. from fertilisation to weaning. Haddock RAG-1 expression was detected after 21 days post-fertilisation (dpf) whilst IgM transcripts were not detected until 40 dpf, equivalent to day 29 post-hatching. These results suggest that the immune system in haddock starts to develop in larvae of 6-7 mm in length (25-29 dph). (c) 2006 Elsevier Ltd. All rights reserved.

Original languageEnglish
Pages (from-to)71-85
Number of pages15
JournalFish & Shellfish Immunology
Issue number1
Early online date4 Oct 2006
Publication statusPublished - Jul 2007


  • haddock
  • RAG-1
  • IgM
  • whole-mount in situ hybridisation
  • gene expression
  • cod gadus-morhua
  • bass dicentrarchus-labrax
  • carp cyprinus-carpio
  • V(D)J recombination
  • lymphoid organs
  • larval haddock
  • Atlantic cod
  • rainbow-trout
  • marine fish
  • expression

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