Comparison of two commercial methods for smooth-shelled mussels (Mytilus spp.) species identification.

Seafood international trade has increased the labeling requirements in standards and regulations to include product information that enable traders and consumers to make informed choices. The European Union (EU) Regulation No. 1379/2013 imposes the declaration of an official commercial designation and scientific names for all the fishery and aquaculture products to be offered for sale to the final consumers. DNA analyses are used to enforce this regulation and to test authenticity in processed foods. We compared the performance of two mono-locus approaches for species identification (SI) in 61 Mytilus mussels: the high-resolution melting analysis of the polyphenolic adhesive protein gene and the partial sequencing of the histone H1C gene. The H1C sequences were analyzed with five different methods. Both approaches show discrepancies in the identification of putative hybrids (0.0 < κ < 0.687 and 0.0 < MCC < 0.724). Excluding putative hybrids, methods show substantial to perfect agreement (0.772 < κ < 1.0 and 0.783 < MCC < 1.0). This study highlights the need to use standardized molecular tools, as well as to use multi-locus methods for SI of Mytilus mussels in testing laboratories.

Evaluation of nucleocapsid and phosphoprotein p functionality as critical factors during the early phase of paramyxoviral infection.

In the beginning of a paramyxovirus infection after cell entry viral survival depends on efficient primary (1°) transcription and on the stability of only one input nucleocapsid. Here we examined the influence of the viral polymerase co-factor phosphoprotein P on the very early phase of an infection, i.e. before progeny nucleocapsids are synthesized. We used a novel set-up with Sendai virus (SeV) mutants incapable of genome replication: SeV-ΔP with the entire P ORF deleted, SeV-PΔ2-77 with the deletion of aa 2-77. These mutants allow maintaining the state of the very beginning of an infection when statistically one viral genome is present in the cell. This single genome serves as template for transcription. During SeV-ΔP infections only early 1° transcription takes place at low levels. However, when the truncated P protein is expressed in SeV-PΔ2-77 infections, 1° transcription levels rise significantly up to an 8-fold increased amount of viral mRNA. This shows that the P protein is able to support transcription and thereby mediates the transition from early to late 1° transcription. Importantly, nucleocapsids of both mutants could be shown to remain stable and functional for at least 5 days - even without de novo P protein synthesis. These results describe a novel function of the P protein: enhancing viral gene expression even before genome replication has started. Thus, the since long postulated supportive function of the P protein is not related to stabilization of the nucleocapsid but rather enhances the processivity of the viral polymerase during late 1° and secondary (2°) transcription and genome replication.

TaqMan-based quantification of invasive cells in the chick embryo metastasis assay.

The chick embryonic metastasis (CEM) assay is a fast in vivo method to investigate the invasive properties of tumor cells. Until now, most quantification methods were semiquantitative and time-consuming. Here we describe a rapid quantification method using TaqMan technology to quantify the invaded tumor cells in the chorioallantoic membrane of fertilized eggs. This method is based on specific detection of human ALU sequences. Moreover, it provides high sensitivity over a wide linearity range.