Detection of extended-spectrum beta-lactamase-producing Escherichia coli isolates in faecal samples of Iberian lynx

Aims: To characterize the diversity of extended‐spectrum beta‐lactamase (ESBL)‐producing Escherichia coli isolates recovered within the faecal microbiota of Iberian lynx. The identification of other associated resistance genes and the analysis of clonal relationship were also focused in this study. Methods and Results: From 2008 to 2010, 128 faecal samples of Iberian lynx (wild and captive animals) were collected. Eleven tested samples contained cefotaxime‐resistant E. coli isolates (all belonging to captive animals) and 10 ESBL‐producing isolates were showed. CTX‐M‐14 and SHV‐12 ESBL‐types were detected and seven different patterns were identified by pulsed‐field gel electrophoresis analysis. Conclusions: The occurrence of unrelated multiresistant E. coli in faecal flora of captive specimens of Iberian lynx, including the presence of ESBLs, resistant genes in integrons and virulence determinants was showed in this study. Significance and Impact of the Study: The results obtained in this study highlight the environmental problem as future reintroductions of Iberian lynx could lead to a spread of resistant bacteria. Additionally, ESBL‐producing bacteria can represent a health problem for this endangered species.     

Transfection improvements of fish cell lines by using deacylated polyethylenimine of selected molecular weights

A new tool for DNA transfer to fish cell lines such as epithelioma papulosum cyprini (EPC) and rainbow trout gonad (RTG2), has been optimized by testing commercially available polyethylenimine (PEI) polymers as transfectant reagents. Deacylated 25 kDa PEI polymers were selected amongst the most active and then low toxicity deacylated PEIs fractions around 15 kDa were obtained by gel filtration chromatography to increase 3–4-fold their initial in vitro transfection efficiency. The EPC and plasmids coding for reporter genes were first used to optimize variable values for best expression by transfection with deacylated low toxicity PEI while both EPC/RTG2 and a plasmid coding for the glycoprotein G gene of the fish pathogen, viral haemorrhagic septicemia virus (VHSV) were then used to demonstrate some of their practical applications. Due to its relatively low price, defined chemical composition and availability, low toxicity deacylated PEI might be used for numerous applications for all those studying fish cell immunology in vitro as well as in vivo.     

Differential effects of oleuropein, a biophenol from Olea europaea, on anionic and zwiterionic phospholipid model membranes

Oleuropein (Ole) is the major phenolic constituent of the olive leaf (Olea europaea) and it is also present in olive oil and fruit. In the last years several compounds from olive tree, oleuropein among them, have shown a variety of biological activities such as antimicrobial or antioxidant. A phospholipid model membrane system was used to study whether the Ole biological effects could be membrane related. Ole showed a significant partition level in phospholipid membranes, i.e. 80%, at lipid-saturating conditions. Moreover, fluorescence quenching experiments indicated a shallow location for Ole in membranes. Ole promoted weak effects on zwiterionic phospholipids such as phosphatidylcholine or phosphatidylethanolamine. In contrast, differential scanning microcalorimetry, light scattering and fluorescence anisotropy pH titration studies revealed strong effects on anionic phospholipids such as phosphatidylglycerol at physiological pH and salt conditions. These effects consisted on perturbations at the phospholipid membrane surface, which might involve specific molecular interactions between Ole and the negatively charged phosphate group and therefore modify the phospholipid/water interface properties. It is proposed that Ole induces lipid structures similar to the gel-fluid intermediate phase (IP) described for PG membranes, in a similar way than low ionic strength does. These effects on phosphatidylglycerol may account for the antimicrobial activity of Ole.     

Mytilus galloprovincialis myticin C: a chemotactic molecule with antiviral activity and immunoregulatory properties

Previous research has shown that an antimicrobial peptide (AMP) of the myticin class C (Myt C) is the most abundantly expressed gene in cDNA and suppressive subtractive hybridization (SSH) libraries after immune stimulation of mussel Mytilus galloprovincialis. However, to date, the expression pattern, the antimicrobial activities and the immunomodulatory properties of the Myt C peptide have not been determined. In contrast, it is known that Myt C mRNA presents an unusual and high level of polymorphism of unidentified biological significance. Therefore, to provide a better understanding of the features of this interesting molecule, we have investigated its function using four different cloned and expressed variants of Myt C cDNA and polyclonal anti-Myt C sera. The in vivo results suggest that this AMP, mainly present in hemocytes, could be acting as an immune system modulator molecule because its overexpression was able to alter the expression of mussel immune-related genes (as the antimicrobial peptides Myticin B and Mytilin B, the C1q domain-containing protein MgC1q, and lysozyme). Moreover, the in vitro results indicate that Myt C peptides have antimicrobial and chemotactic properties. Their recombinant expression in a fish cell line conferred protection against two different fish viruses (enveloped and non-enveloped). Cell extracts from Myt C expressing fish cells were also able to attract hemocytes. All together, these results suggest that Myt C should be considered not only as an AMP but also as the first chemokine/cytokine-like molecule identified in bivalves and one of the few examples in all of the invertebrates.     

Fish transposons and their potential use in aquaculture

A large part of repetitive DNA of vertebrate genomes have been identified as transposon elements (TEs) or mobile sequences. Although TEs detected to date in most vertebrates are inactivated, active TEs have been found in fish and a salmonid TE has been successfully reactivated by molecular genetic manipulation from inactive genomic copies (Sleeping Beauty, SB). Progress in the understanding of the dynamics, control and evolution of fish TEs will allow the insertion of selected sequences into the fish genomes of germ cells to obtain transgenics or to identify genes important for growth and/or of somatic cells to improve DNA vaccination. Expectations are high for new possible applications to fish of this well developed technology for mammals. Here, we review the present state of knowledge of inactive and active fish TEs and briefly discuss how their possible future applications might be used to improve fish production in aquaculture.     

Recent shoreline changes in the Volta River delta,West Africa: the roles of natural processes and human impacts§

The Volta River delta developed as an asymmetric lobe in a tectonic offset on the coast of Ghana. The delta comprises a large curvilinear spit that widens in its central portion due to the adjunction of successive sandy beach ridges. The appearance of a distinct spit, in lieu of a continuous barrier from the present mouth of the Volta River to the Bight of Benin coast, may be an outgrowth of a natural change in the location of the mouth of the Volta. The spit marks a segmentation of the unique sand drift cell that hitherto prevailed on this bight coast. Spit growth has been accompanied by a wave of erosion over the last century of the immediate downdrift sector of the bight coast, endangering the town of Keta. Erosion since the 1960s may have been aggravated by the construction of the Akosombo hydropower dam. The tip of the spit has recently welded to the shoreline, thus assuring resumption of sand supply from the Volta towards the rest of this formerly sand-starved sector of the bight coast. Blocking of sediment by the Akosombo Dam is, in due course, likely to become the overarching factor in delta shoreline stability.