RESUMO
Disease is caused by a complex interaction between the pathogen, environment, and the physiological status of the host. Determining how host ontogeny interacts with water temperature to influence the antiviral response of the Pacific oysters, Crassostrea gigas, is a major goal in understanding why juvenile Pacific oysters are dying during summer as a result of the global emergence of a new genotype of the Ostreid herpesvirus, termed OsHV-1 µvar. We measured the effect of temperature (12 vs 22 °C) on the antiviral response of adult and juvenile C. gigas injected with poly I:C. Poly I:C up-regulated the expression of numerous immune genes, including TLR, MyD88, IκB-1, Rel, IRF, MDA5, STING, SOC, PKR, Viperin and Mpeg1. At 22 °C, these immune genes showed significant up-regulation in juvenile and adult oysters, but the majority of these genes were up-regulated 12 h post-injection for juveniles compared to 26 h for adults. At 12 °C, the response of these genes was completely inhibited in juveniles and delayed in adults. Temperature and age had no effect on hemolymph antiviral activity against herpes simplex virus (HSV-1). These results suggest that oysters rely on a cellular response to minimise viral replication, involving recognition of virus-associated molecular patterns to induce host cells into an antiviral state, as opposed to producing broad-spectrum antiviral compounds. This cellular response, measured by antiviral gene expression of circulating hemocytes, was influenced by temperature and oyster age. We speculate whether the vigorous antiviral response of juveniles at 22 °C results in an immune-mediated disorder causing mortality.
Assuntos
Crassostrea/virologia , Infecções por Herpesviridae/imunologia , Herpesviridae/imunologia , Poli I-C/farmacologia , Regulação para Cima/imunologia , Animais , Crassostrea/imunologia , Infecções por Herpesviridae/virologia , Proteínas I-kappa B/imunologia , Fator Regulador 1 de Interferon/imunologia , Análise Multivariada , Fator 88 de Diferenciação Mieloide/imunologia , Proteínas Proto-Oncogênicas c-rel/imunologia , RNA/química , RNA/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Temperatura , Receptores Toll-Like/imunologia , Replicação Viral/imunologiaRESUMO
Nacre of the Pinctada pearl oyster shells is composed of 98% CaCO3 and 2% organic matrix. The relationship between the organic matrix and the mechanism of nacre formation currently constitutes the main focus regarding the biomineralization process. In this study, we isolated a new nacre matrix protein in P. margaritifera and P. maxima, we called Pmarg- and Pmax-MRNP34 (methionine-rich nacre protein). MRNP34 is a secreted hydrophobic protein, which is remarkably rich in methionine, and which is specifically localised in mineralizing the epithelium cells of the mantle and in the nacre matrix. The structure of this protein is drastically different from those of the other nacre proteins already described. This unusual methionine-rich protein is a new member in the growing list of low complexity domain containing proteins that are associated with biocalcifications. These observations offer new insights to the molecular mechanisms of biomineralization.
Assuntos
Calcificação Fisiológica , Metionina , Pinctada , Proteínas/isolamento & purificação , Sequência de Aminoácidos , Animais , Células Epiteliais/química , Expressão Gênica , Metionina/química , Dados de Sequência Molecular , Nácar/química , Pinctada/química , Estrutura Terciária de Proteína , Proteínas/química , Proteínas/genéticaRESUMO
We have cloned and characterized a cDNA encoding Cg-tal in the Pacific oyster Crassostrea gigas. The isolated cDNA encodes a 219 amino acids protein that contains the basic helix-loop-helix (bHLH) domain homologous to that of vertebrate and invertebrate Tal1/SCL. Phylogenetic analyses sustained that Cg-Tal belongs to this family of bHLH transcription factors. Northern blot analysis of Cg-tal mRNA expression in adult oyster tissues indicated that Cg-ta1 was specifically expressed in hemocytes, in a constitutive manner. In vertebrates, activation of Tal1/SCL expression is essential for the initiation of hematopoiesis and the formation of hematopoietic stem cells. Considering Tal1/SCL function in vertebrates, Cg-Tal is likely to constitute a promising tool for studying hematopoiesis in oyster.