Project description:The Squalius alburnoides complex (Steindachner) is one of the most intricate hybrid polyploid systems known in vertebrates. In this complex, the constant switch of the genome composition in consecutive generations, very frequently involving a change on the ploidy level, promotes repetitive situations of potential genomic shock. Previously in this complex, it was shown that in response to the increase in the genome dosage, triploid hybrids could regulate gene expression to a diploid state. In this work, we compared the small RNA profiles in the different genomic compositions interacting in the complex. Using high-throughput arrays and sequencing technologies, we were able to verify that diploid and triploid hybrids were closely related: they shared most of their sequences and their miRNA expression profiles were highly correlated. However, an overall view indicates an up-regulation of a substantial number of miRNAs in triploids. Also, the global miRNA expression in triploids was higher than predicted from an additive model. These results point to a participation of miRNAs in the cellular functional stability needed when the ploidy change.
Project description:The Squalius alburnoides complex (Steindachner) is one of the most intricate hybrid polyploid systems known in vertebrates. In this complex, the constant switch of the genome composition in consecutive generations, very frequently involving a change on the ploidy level, promotes repetitive situations of potential genomic shock. Previously in this complex, it was shown that in response to the increase in the genome dosage, triploid hybrids could regulate gene expression to a diploid state. In this work, we compared the small RNA profiles in the different genomic compositions interacting in the complex. Using high-throughput arrays and sequencing technologies, we were able to verify that diploid and triploid hybrids were closely related: they shared most of their sequences and their miRNA expression profiles were highly correlated. However, an overall view indicates an up-regulation of a substantial number of miRNAs in triploids. Also, the global miRNA expression in triploids was higher than predicted from an additive model. These results point to a participation of miRNAs in the cellular functional stability needed when the ploidy change.
Project description:A novel virus from moribund European chub (Squalius cephalus) was isolated on epithelioma papulosum cyprini (EPC) cells. Transmission electron microscopic examination revealed abundant non-enveloped, hexagonal virus particles in the cytoplasm of infected EPC cells consistent with an iridovirus. Illumina MiSeq sequence data enabled the assembly and annotation of the full genome (128,216 bp encoding 108 open reading frames) of the suspected iridovirus. Maximum Likelihood phylogenetic analyses based on 25 iridovirus core genes supported the European chub iridovirus (ECIV) as being the sister species to the recently-discovered scale drop disease virus (SDDV), which together form the most basal megalocytivirus clade. Genetic analyses of the ECIV major capsid protein and ATPase genes revealed the greatest nucleotide identity to members of the genus Megalocytivirus including SDDV. These data support ECIV as a novel member within the genus Megalocytivirus. Experimental challenge studies are needed to fulfill River's postulates and determine whether ECIV induces the pathognomonic microscopic lesions (i.e., megalocytes with basophilic cytoplasmic inclusions) observed in megalocytivirus infections.