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a b s t r a c tPaola Ridge, along the NW Calabrian margin (southern Tyrrhenian Sea), is one of the few reported deep sea sites of precipitation of authigenic carbonates in the Tyrrhenian Sea. Here, the changing composition of the seeping fluids and the dynamic nature of the seepage induced the precipitation of pyrite, siderite and other carbonate phases. The occurrence of this array of authigenic precipitates is thought to be related to fluctuation of the sulfate-methane transition zone (SMTZ).Concretions of authigenic minerals formed in the near sub-bottom sediments of the Paola Ridge were investigated for their geochemical and isotopic composition. These concretions were collected in an area characterized by the presence of two alleged mud volcanoes and three mud diapirs. The mud diapirs are dotted by pockmarks and dissected by normal faults, and are known for having been a site of fluid seepage for at least the past 40 kyrs. Present-day venting activity occurs alongside the two alleged mud volcanoes and is dominated by CO 2 -rich discharging fluids. This discover led us to question the hypothesis of the mud volcanoes and investigate the origin of the fluids in each different domed structure of the study area.In this study, we used stable isotopes (carbon and oxygen) of carbonates coupled with rare earth element (REE) composition of different carbonate and non-carbonate phases for tracing fluid composition and early diagenesis of authigenic precipitates. The analyses on authigenic precipitates were coupled with chemical investigation of venting gas and sea-water.Authigenic calcite/aragonite concretions, from surficial sediments on diapiric structures, have depleted values. The siderite REE pattern shows consistent LREE (light REE) fractionation, MREE (medium REE) enrichment and positive Gd and La anomalies. As shown by the REE distribution, the 13 C-depleted composition and their association with chemosymbiotic fauna, calcite/aragonite precipitated at time of moderate to high methane flux close to the seafloor, under the influence of bottom seawater. Authigenic siderite, on the other hand, formed in the subseafloor, during periods of lower gas discharges under prolonged anoxic conditions within sediments in equilibrium with 13 C-rich dissolved inorganic carbon (DIC) and 18 O-rich water, likely related to methanogenesis and intermittent venting of deep-sourced CO 2 .

Infectious bursal disease consider a vital threat to poultry industry worldwide and It has special potentiality in Egypt as the country become endemic with several clades from avian influenza from both types highly pathogenic (H5N1 and H5N8) and low pathogenic one (H9N2). The Egyptian government depends on the inactivated vaccine strategy to control avian influenza and any infection with IBD in broiler flocks alter the inactivated vaccine response in addition to other economic loss from the IBD infections. The present study was conducted to investigate the variations in pathogenicity and molecular characterization of IBDV in Egypt. Twenty-six bursal samples were collected from different chicken farms during the period of June 2015 to April 2016; the virus was isolated by inoculation of bursal suspension into 10-11 days ECE via CAM. Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) was applied for IBD targeting Hypervariable Region (HVR) of VP2 gene. Out of 26 tested isolates, 11 isolates were positive by RT-PCR. Sequence analysis of PCR products of 11 positive isolates were carried out and revealed that all +ve isolates were characterized as very virulent (vvIBDV) strains and they showed 80.6-97.5% identity with Giza 2008 IBD strain. Six selected positive vvIBDV isolates were used to study the pathogenicity of IBDV in 105 one-day-old SPF chickens. At day 211st the SPF chickens were divided into 7 groups 15 bird/each, the groups 1-6 were experimentally infected with 0.1 mL of EID50 of 6 selected positive IBDV field isolates via nasoocular route. Group 7 kept as non-infected control. Experimental infection caused clinical signs and gross lesions typical for IBDV and mortalities ranged from 26.7 to 80% as well as bursal/body weight index lower than 0.7 indicating bursal atrophy. The Microscopical examination of bursal samples collected at days 3 and 7 post-infection revealed different degrees of histopathological bursal changes as lymphoid depletion with proliferating interfollicular connective tissue, atrophy of the follicles, stromal edema and associated with inflammatory response. The circulating strains were highly related to vvIBDV strains belonging to serotype-1 isolates and indicating that they are highly pathogenic to 21-day-old SPF chickens and that vvIBDV strains succeeded in surviving in the Egyptian farms despite of the application of intensive vaccination programs.

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