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PERSEUS project aims to identify the most relevant pressures exerted on the ecosystems of the Southern European Seas (SES), highlighting knowledge and data gaps that endanger the achievement of SES Good Environmental Status (GES) as mandated by the Marine Strategy Framework Directive (MSFD). A complementary approach has been adopted, by a meta-analysis of existing literature on pressure/impact/knowledge gaps summarized in tables related to the MSFD descriptors, discriminating open waters from coastal areas. A comparative assessment of the Initial Assessments (IAs) for five SES countries has been also independently performed. The comparison between meta-analysis results and IAs shows similarities for coastal areas only. Major knowledge gaps have been detected for the biodiversity, marine food web, marine litter and underwater noise descriptors. The meta-analysis also allowed the identification of additional research themes targeting research topics that are requested to the achievement of GES. 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license., peer-reviewed

The present study is aimed at implementing the amplicon sequence variant (ASV) concept to describe meiofaunal species composition independent of morphological identification, while strongly indicating reasonable compatibility with the underlying species. A primer pair was constructed and demonstrated to PCR amplify an 18S barcode from a variety of meiofaunal taxa, compatible with the high throughput sequencing (HTS) Illumina 300 X 2 bps platform. Sixteen 18S multi-species HTS assemblies were created from meiofaunal samples and merged to one assembly of ~2,150,000 contigs. Five quality scores (q=35, 30, 25, 20, 15) were implemented to filter five 18S barcode assemblies, which served as inputs to the DADA2 software, ending with 5 reference ASV libraries. Each of them was clustered, applying 3% dissimilarity threshold and revealed an average number of 1.38±0.078 ASVs/cluster which demonstrate high level of ASV uniqueness. The libraries which were based on q ≤ 25 reached a near-asymptote number of ASVs which together with the low average number of ASVs/3% cluster, strongly indicate compatibility with the actual number of underlying species. Hence, the q=25 library was selected to be used as metabarcoding reference library. It contained 461 ASVs and 342 - 3% clusters with average number of 1.34±1.036 ASV/cluster and their BLASTN annotation elucidated the expected meiofaunal taxa. The 16 assemblies of sample-specific paired contigs were mapped to this reference library and sample ASV profiles, namely the list of ASVs and their proportional copy numbers were created and also normalized to the actual number of individuals in each sample.

The red swamp crayfish (. Procambarus clarkii, Girard 1852) is among the most economically important freshwater crustacean species, and it is also considered one of the most aggressive invasive species worldwide. Despite its commercial importance and being one of the most studied crayfish species, its genomic and transcriptomic layout has only been partially studied. Illumina RNA-sequencing was applied to characterize the eyestalk transcriptome and identify its most characterizing genes. A collection of 83,170,732 reads from eyestalks was obtained using Illumina paired-end sequencing technology. A de novo assembly was performed with the Trinity assembly software generating 119,255 contigs (average length of 1007. bp) and identifying the first sequenced transcriptome in this species.The eyestalk is a major site for the production of neurohormones and controls a variety of physiological functions such as osmotic regulation, molting, epidermal color patterns and reproduction. Hence, its transcriptomic characterization is interesting and potentially instrumental to the elucidation of genes which have not been comprehensively described yet. Moreover, the availability of such a large amount of information supported the characterization of molecular families which have never been described before. The P. clarkii eyestalk transcriptome reported here provides a resource for improving the knowledge of the still incompletely defined neuroendocrinology of this species and represents an important source of data for all the interested carcinologists.

Conversion of one or more amino acids in eukaryotic peptides to the D-configuration is catalyzed by specific L/D peptide isomerases and it is a poorly investigated post-translational modification. No common modified amino acid and no specific modified position have been recognized and mechanisms underlying changes in the peptide function provided by this conversion were not sufficiently studied. The 72 amino acid crustacean hyperglycemic hormone (CHH) of Astacidea crustaceans exhibits a co-existence of two peptide enantiomers alternately having D- or L-phenylalanine in their third position. It is a pleiotropic hormone regulating several physiological processes in different target tissues and along different time scales. CHH enantiomers differently affect time courses and intensities of examined processes. The short-term effects of the two isomers on gene expression are presented here, examined in the hepatopancreas, gills, hemocytes and muscles of the astacid Pontastacus leptodactylus. Muscles and hemocytes were poorly affected by both isomers. Two CHH modes of action were elucidated in the hepatopancreas and the gills: specific gene induction by D-CHH only, elucidated in both organs and mutual targeted attenuation affected by both enantiomers elucidated in the gills. Consequently a two-receptor system is hypothesized for conveying the effect of the two CHH isomers.