Deep transcriptome sequencing of Pecten maximus hemocytes: a genomic resource for bivalve immunology.
Pecten maximus, the king scallop, is a bivalve species with important commercial value for both fisheries and aquaculture, traditionally consumed in several European countries. Major problems in larval rearing, however, still limit hatchery-based seed production. High mortalities during early larval stages, likely related to bacterial pathogens, represent the most relevant bottleneck. To address this issue, understanding host defense mechanisms against microbes is extremely important. In this study next-generation RNA-sequencing was carried on scallop hemocytes. To enrich for immune-related transcripts, cDNA libraries from hemocytes challenged in vivo with inactivated-Vibrio anguillarum and in vitro with pathogen-associated molecular patterns, as well as unchallenged controls, were sequenced yielding 216,444,674 sequence reads. De novo assembly of the scallop hemocyte transcriptome consisted of 73,732 contigs (31% annotated). A total of 934 contigs encoded proteins with a known immune function, grouped into several functional categories. Particular attention was reserved to Toll-like receptors (TLRs), a family of pattern recognition receptors (PRRs) involved in non-self recognition. Through mining the scallop hemocyte transcriptome, at least four TLRs could be identified. The organization of canonical TLR domains demonstrated that single cysteine cluster and multiple cysteine cluster TLRs co-exist in this species. In addition, preliminary data concerning their mRNA level following bacterial challenge suggested that different members of this family could exhibit opposite responses to pathogenic stimuli. Finally, a global analysis of differential expression comparing gene-expression levels in in vitro and in vivo stimulated hemocytes against controls provided evidence on a large set of transcripts involved in the great scallop immune response.
Department of Comparative Biomedicine and Food Science, University of Padova, Viale dell'Università 16, 35020 Legnaro, PD, Italy. Electronic address: marianna.pauletto@studenti.unipd.it.
Marianna
M
Pauletto
Department of Comparative Biomedicine and Food Science, University of Padova, Viale dell'Università 16, 35020 Legnaro, PD, Italy. Electronic address: massimo.milan@unipd.it.
Massimo
M
Milan
Instituto de Investigaciones Marinas (IIM), CSIC, C/Eduardo Cabello 6, 36208 Vigo, Pontevedra, Spain. Electronic address: rebecamoreira@iim.csic.es.
Rebeca
R
Moreira
Instituto de Investigaciones Marinas (IIM), CSIC, C/Eduardo Cabello 6, 36208 Vigo, Pontevedra, Spain. Electronic address: beatriznovoa@iim.csic.es.
Beatriz
B
Novoa
Instituto de Investigaciones Marinas (IIM), CSIC, C/Eduardo Cabello 6, 36208 Vigo, Pontevedra, Spain. Electronic address: antoniofigueras@iim.csic.es.
Antonio
A
Figueras
Department of Comparative Biomedicine and Food Science, University of Padova, Viale dell'Università 16, 35020 Legnaro, PD, Italy. Electronic address: massimiliano.babbucci@unipd.it.
Massimiliano
M
Babbucci
Department of Comparative Biomedicine and Food Science, University of Padova, Viale dell'Università 16, 35020 Legnaro, PD, Italy. Electronic address: tomaso.patarnello@unipd.it.
Tomaso
T
Patarnello
Department of Comparative Biomedicine and Food Science, University of Padova, Viale dell'Università 16, 35020 Legnaro, PD, Italy. Electronic address: luca.bargelloni@unipd.it.
Luca
L
Bargelloni
D000818:Animals; D001483:Base Sequence; D023082:Defensins / Q000235:genetics / Q000378:metabolism; D015723:Gene Library; D006434:Hemocytes / Q000378:metabolism*; D059014:High-Throughput Nucleotide Sequencing; D016013:Likelihood Functions; D008957:Models, Genetic; D008969:Molecular Sequence Data; D049910:Pecten / Q000235:genetics* / Q000276:immunology*; D010802:Phylogeny; D017423:Sequence Analysis, RNA; D013030:Spain; D059467:Transcriptome / Q000235:genetics*
D023082:Defensins
Hemocytes; Innate immunity; Next generation sequencing; Pecten maximus; Transcriptome