title: RAG-1 and IgM genes, markers for early development of the immune system in the gadoid haddock, Melanogrammus aeglefinus, L.
abstract: 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).
authors.affiliation: Scottish Fish Immunology Research Centre, University of Aberdeen, Aberdeen AB24 2TZ, Scotland, UK. y.corripio@abdn.ac.uk
authors.forename: Y
authors.initials: Y
authors.lastname: Corripio-Miyar
authors.forename: S
authors.initials: S
authors.lastname: Bird
authors.forename: J W
authors.initials: JW
authors.lastname: Treasurer
authors.forename: C J
authors.initials: CJ
authors.lastname: Secombes
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D017931:DNA Primers; D018076:DNA, Complementary / Q000235:genetics; D048388:Gadiformes / Q000235:genetics* / Q000276:immunology; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D007107:Immune System / Q000254:growth & development*; D007075:Immunoglobulin M / Q000235:genetics* / Q000378:metabolism; D017403:In Situ Hybridization; D016015:Logistic Models; D008969:Molecular Sequence Data; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
chemical_list: D017931:DNA Primers; D018076:DNA, Complementary; D018398:Homeodomain Proteins; D007075:Immunoglobulin M; C064658:RAG-1 protein