The emergence of Ophuirid IGKappa gene, of Fab fragment gene occured in the Ophuirid : Ophiocomina nigra genome, when a Fc receptor gene was found in this last one.Notions of adaptative immunity , in Echinodermata have to be revieviewed and It’s a great novelty since it was spoken of invertebrates
Keywords: Invertebrate, Ophuirids, Ophiocomina Nigra, Fab Fragment Gene, Primitive Antibody
Introduction:
We recall the emergence of primitive antibody in two classes of Echinodermata : the asterids and the ophuirids. The characteristics of sea star antibody are the presence of Ig sites, Fab fragment site ( Ref.1) ancd Fc receptor site ( Ref.2). We have just discovered the Ophuirid IGKappa gene ( Ref.3)The aim of this paper is to look for Fc receptor gene in the Ophiocomina nigra genome.We say again : it is a great novelty in Invertebrate immune response studies and particularly in adaptative immunity in Invertebrates
Materials and Methods :
Animals :
Ophiocomina nigra was obtained at the station « Of Biologie Marine of Roscoff » France
Obtention of ophuirid mRNA :
Digestive coeca were excised from the O.nigra body.
O.nigra mRNA was obtained from Uptizol (Interchim). Quality control were operated.
Sequencing :
Sequencing was made on Illumina Next Seq 500 with paired-end : 2. 75 bp
Transcriptome was assembled from RNA-Seq fastq files using Trinity v2.1.1 ( Ref.4) with default parameters. A BLAST database was created with the assembled transcripts using makeblastdb application from ncbi-blast+ (v2.2.31+). The sequences of transcripts of interest were then blasted against this database using blastn application from ncbi-blast+ ( Ref.5) with parameter word_size 7.
Results
The transcriptome shows a sequence of Fc receptor gene as following :
>NM_001253737.1 Fcer2a (14128) Fc receptor / Mus musculus Fc receptor, IgE, low affinity II, alpha polypeptide (Fcer2a), transcript variant 2, mRNA
5’GAAAGCCAATTTGAACGGGAACTTGGAATTCAGAATGAATTCTCAAAACCAGGGATACTGGGAACCTCCT
AGAAAGCGTTGCTGCTGTGCAAGACGTGGGACACAGCTCATGTTGGTGGGGCTGCTGAGCACAGCAATGT
GGGCTGGCCTGCTGGCCCTGCTTCTTCTGTGGCACTGGGAAACGGAGAAGAATCTAAAACAGCTGGGAGA
CACTGCAATTCAGAATGTCTCTCATGTTACCAAGGACTTACAAAAATTCCAGAGTAATCAATTGGCCCAG
AAGTCCCAGGTTGTTCAGATGTCACAAAACTTGCAAGAACTCCAAGCTGAACAGAAGCAAATGAAAGCTC
AGGACTCTCGGCTCTCCCAGAACCTGACCGGACTCCAGGAGGATCTAAGGAACGCCCAATCCCAGAACTC
AAAACTCTCCCAGAACCTGAACAGACTCCAAGACGATCTAGTCAACATCAAATCCCTGGGCTTGAATGAG
AAGCGCACAGCCTCCGATTCTCTAGAGAAACTCCAGGAAGAGGTGGCAAAGCTGTGGATAGAGATACTGA
TTTCAAAGGGAACTGCATGCAACATATGTCCCAAGAACTGGCTCCATTTCCAACAGAAGTGCTACTATTT
TGGCAAGGGCTCCAAGCAGTGGATCCAGGCCAGGTTCGCCTGCAGTGACCTGCAAGGGCGACTAGTCAGC
ATCCACAGCCAAAAGGAACAGGACTTCCTGATGCAACACATCAACAAGAAGGATTCCTGGATTGGCCTCC
AGGATCTCAATATGGAGGGAGAGTTTGTATGGTCGGACGGGAGCCCTGTGGGTTATAGCAACTGGAATCC
AGGGGAGCCCAATAACGGGGGCCAGGGTGAGGACTGTGTGATGATGCGGGGATCCGGCCAGTGGAACGAC
GCCTTCTGCCGCAGCTACTTGGATGCATGGGTGTGTGAGCAGCTGGCAACATGTGAGATATCTGCCCCCT
TAGCCTCTGTGACTCCAACAAGGCCCACCCCAAAAAGTGAACCCTGACAAACTTCTGCTCACACTCTTCT
GGATTTCTCCTCTACCTTTATCGTGGAAACAGCTGGGCCCTGAGGATACCCCTATCAGGGCCCAGGGCCC
TCTCTGTGACCGAAGGCTTTGATTATGTTCCCACCCATACTGAAGCAGCTGGTGGATGCCAGCTCCTGCC
AGCTACCCAGAAACCCTCTCCAGCTCTCCAGCTAAGCTGGCCATCCCATTCCATCTGCCTTCCTCAAACC
TGGGCCCCAGCCTTGCTAGCTCCCTGACTACGGGCATGCATGTGGGCAGCTGAGCCAACCAGGGAGCTGC
TGAGAACAAAGATTTCGAAGGCTTCTTTTGCAGTCCCCACCTCCTATCAAGTTCCCCACTTTCTCCCCCT
CGGCATCAGAGAACAGGGGTTCCCTTTCCCCAGGATCTGGGATGAGTCCTCCCATCAAGTTTGCATCAGT
GGTCCCAGCACTCCGACCCTCCTTGGAGGCTGCACCAGGTGTGCTCCTGGTGCGGGAGGTATTGAAGGAA
CTCTAAACAGCTCCAGCAAGGCGAGCCTGGCTCTGTCTGGTAGGCCTGGCCCTTCTCTCCCATTCCTTCT
ACCTTACTAAAAGCTGTTAGAGAACAGTCCTAAAGCTAGCCCCCAAGGTCTATTCCCTTATTTGGCCACT
TCCTCCTCCTGAGGCTGACTACAAGGTCCAGCTATCCAAGTACTGAAGTCTAACATCAAAAGCCCCCTTT
GTCTCACCTAAGTAGCAATGCCCAATCAAAATACACCATCACATCATAGCCCAGTCTAACAGACCGCCCT
TTTTCTCTTCATAAAATTACACCTGCAACCAGGCGTAGTGGTGCAGGCCTTTAGTCCCAGCACTTGGGAG
GCAGAGACAAGCGAATTTCTGAGTTCGAGGCCAGCCTGGTCTACAAAGTGAGTTCCAGGACAGCCAGGGC
TACACAGAGAAACCCTGTCTCGAAGAAAGAAAAAAAAAAAAAATTACACCTGCAAGGTCACTTGCAGGCT
GCTGTTTTTCTGCCTGAGTCAGAGGGCAGCCACTTAACTTTTCTTCCCTGCTTAATAAAGGATCTCTGTG3’
The identity with mouse is 94,29 % and The e-value : 2,00E-07.So, it is higly significant.
Discussion and Conclusion
The Fc found sequence is longer(2100 nucleotides) than the one observed in the sea star Asterias rubens(400 nucleotides). Both share a common part and recall mouse Fc IgE low affinity one ( Ref. 2)
It’s interesting from a point of view of phylogeny of the Fc receptor genes in Invertebrates. Now, from a point of view of evolution :
It remains striking to find such elaborated genes in species which appeared in Cambrian. We recall that the Cambrian period was the first
geological period of the Palezoic Era..
Whatever the level that the Echinodermata( Asterids, Ophuirids) occupy in the phylogenetic domain, their various immune system accomodate and indeed ensure their survival.
On the other hand, we assume the existence of primitive antibody, in Asterids and in Ophuirids and so in Invertebrates.That constitutes
a bomb in comparative and evolutive Immunology.
