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Polymorphisms at codon 171 of the sheep prion protein gene (PRNP) are known to be genetically associated with scrapie ( Hunter et al., 1993 , Hunter et al., 1997 ). Glutamine (Q) and histidine (H) at codon 171 contribute to scrapie susceptibility, while arginine (R) is associated with resistance. In some breeds, lysine (K) occurs at codon 171 (171 K), but its effect on scrapie resistance has not been fully determined yet. To investigate the role of 171 K in dairy sheep in Greece, we initially analyzed blood samples from 2368 sheep with no clinical signs of the disease, from thirteen scrapie-affected flocks that were then monitored for 5 years for scrapie clinical signs. During this period 177 sheep resulted positive in classical scrapie, after obex testing. The 177 scrapie-affected brain samples PRNP polymorphisms were analyzed using a Real Time-PCR protocol while the 2368 sheep blood samples were analyzed by a micro-array method based on primer extension (Homogenous Mass Extend Assay – SEQUENOM, Genaissance Pharmaceuticals) in MALDI-TOF-MS. Single Nucleotide Polymorphisms (SNPs) present at PRNP codons 136A/V (Alanine/Valine), 154R/H and 171Q/R/H/K were detected. The ARQ haplotype as well as the ARQ/ARQ genotype predominated. In the studied population, ARK haplotype was found at the highest frequency reported so far (6.98%) whereas, ARK/-genotypes had a total frequency of 12.81%. Relative risk (RR) and the percent relative effect were calculated to assess the association between ARK/-genotypes and scrapie affection. The results showed that carriers of K allele at codon 171 compared to Q and H alleles had ca. 0.25 and 0.40 times the risk of scrapie affection, respectively, indicating a possible association of K allele at codon 171 with scrapie resistance.

The objective of this study was to estimate the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in the production chain of dairy products. Of 367 tested samples (36 bulk tank milk (BTM), 19 dairy products, 72 human, 185 animal, 55 equipment), 212 (57.8%) were found positive for S. aureus. Almost all isolates (99.6%) were resistant to at least one antimicrobial and 13.3% were multi-drug resistant (MDR), exhibiting resistance to three or more antibiotic classes. Eleven samples (3%) were found contaminated by MRSA carrying the mecA gene. None of the MRSA isolates carried the mecC or the Pandon-Valentine leucocidin (PVL) genes. Four spa types were identified among the MRSA isolates: t127, t3586, t1773, t4038, with t127 being the most prevalent (7 out of 11). Two of them, t3586 and t1773, were isolated for the first time in Greece. Furthermore, Pulse-Field Gel Electrophoresis (PFGE) analysis indicated clonal circulation through the dairy production chain. The presence of MDR S. aureus, and especially MRSA, in animals and dairy products represents a potential threat for the spread of this pathogen in the community. The results indicated that human, animal and environmental sources could be involved in the contamination of dairy products along their production chain and therefore further investigation of contamination sources is needed to control the dispersion of MRSA in the community.

Τo exploit the solid residue of olive mill wastewaters (OMWS) towards the production of an olive paste-type product, natural fermentation of OMWS in NaCl (6% w/v) was implemented for 14 days at 20 °C. The microbiological and physicochemical characteristics of OMWS were examined during fermentation. Fermentation of OMWS was shown to be relied on yeasts while absence of enterobacteria, pseudomonads and staphylococci as well as LAB was observed. Molecular identification of yeast included RFLP analysis of the 5.8S-ITS region. For some selected isolates, sequence analysis of the 5.8S-ITS region was performed. The results were compared to sequences held in public databases (NCBI) and data of papers published previously. These techniques allowed to identify the isolates as Saccharomyces cerevisiae (99% homology) and Pichia membranefasciens (100% homology). Beta-glucosidase was the most important biochemical activity observed, mainly responsible for removing the bitter taste. Paste preparations of fermented OMWS did not differ in sensory characteristics than the controls.

We have identified and characterized a cDNA from the brain tissue of the highly commercial marine fish species, the gilthead sea bream (Sparus aurata), which encodes a 496 amino acid residue protein sharing the organizational and structural features of the mammalian prion proteins. Tissue mRNA expression analyses revealed the presence of this transcript in various tissues of the gilthead sea bream including the brain, the spleen, and the heart. Sequence comparison and phylogenetic analysis showed the gilthead sea bream protein to be the homologue of one of the long form prion proteins identified from the model fish species Takifugu rubripes and Danio rerio. Unique to this fish prion protein is an extended Gly-Tyr-Pro-rich region, a structural feature that apparently resulted from multiple duplications of a core motif. The presence of this feature in other seemingly unrelated proteins suggests the involvement of common mechanism(s) in its formation and infers possible evolutionary trends related to its function.

To maximize growth, farmed fish are fed high-fat diets, which can lead to high tissue lipid concentrations that have an impact on quality. The intake of conjugated linoleic acid (CLA) reduces body fat in mammals and this study was undertaken to determine the effects of dietary CLA on growth, composition, and postprandial metabolic variables in sea bream. Fish were fed 3 diets containing 48 g/100 g protein and 24 g/100 g fat, including fish oil supplemented with 0 (control), 2, or 4% CLA for 12 wk. Feed intake, specific growth rate, total body fat, and circulating somatolactin concentration were lower in fish fed CLA than in controls. Feed efficiency was greater in fish fed 2% CLA than in controls. Liver triglyceride concentrations were higher in fish fed 4% CLA and muscle triglyceride concentrations were lower in fish fed both CLA diets than in controls. Hepatic fatty acyl desaturase and elongase mRNA levels in fish fed CLA were lower than in controls. Metabolic differences between controls and CLA-fed fish were observed at 6 h but not at 24 h after the last meal, including lower postprandial circulating triglyceride concentrations, higher hepatic acyl-CoA-oxidase, and lower L-3-hydroxyacyl-CoA dehydrogenase activities in CLA-fed fish than in controls. Dietary CLA did not affect enzymes involved in lipogenesis including hepatic fatty acid synthase and malic enzyme, but it decreased glucose 6-phosphate dehydrogenase activity at 24 h, but not at 6 h after feeding. The data suggest that CLA intake in sea bream has little effect on hepatic lipogenesis, channels dietary lipid from adipose tissue to the liver, and switches hepatic mitochondrial to peroxisomal beta-oxidation.

The correlation between the natural levels of GST and the tolerance to the insecticide decamethrin (dMT), as well as the interaction between the molecules of affinity purified enzyme and the insecticide were investigated in order to collect further information on the obscure role of the Glutathione S-transferase system (GST) as a mechanism of defence against pyrethroids. The studies were carried out, comparatively, on the larvae and pupae developmental stages of the coleopteran Tenebrio molitor, which exhibit varying natural levels of GST activity. No stage dependent susceptibility of the insect against pyrethroid insecticides was found during the first 24 h, however 48 h after treatment, the KD50 dose increased significantly due to the recovery of some individuals from the larvae stage. Simultaneous injection of decamethrin with compounds which inhibit GST activity in vitro, resulted in an increased tolerance, which was more pronounced in the pupae stage. Inhibition studies combined with competitive fluorescence spectroscopy and high pressure liquid chromatography (HPLC) showed that the insecticide binds probably to the active site of the enzyme inhibiting its activity towards CDNB in a competitive manner, but is not conjugated with GSH. According to this, GST offers a passive protection towards pyrethroid insecticides by binding to their molecule in a sequestering mechanism.