31. Artificially induced migration of redox layers in a coastal sediment from the Northern AdriaticEduard Metzger, D. Langlet, E. Viollier, Neža Koron, Bettina Riedel, Michael Stachowitsch, Jadran Faganeli, M. Tharaud, E. Geslin, F. Jorissen, 2014, original scientific article Abstract: Long-term experimental studies suggest that, under transient anoxic conditions, redox fronts within the sediment shift upwards, causing sequential rise and fall of benthic fluxes of reduced species (Mn(II), Fe(II) and S(-II)). Infaunal benthic organisms are associated with different redox fronts as micro-habitats and must be affected by such changes during natural hypoxia events. In order to document the geochemical evolution of the sediment during prolonged anoxia in the framework of an in situ experiment designed to mimic natural conditions, benthic chambers were deployed on the seafloor of the Northern Adriatic and sampled after 9, 30 and 315 days of incubation. Oxygen and sulfide were measured continuously in the early stages (9 days) of the experiment. High-resolution pore water profiles were sampled by DET probes and redox-sensitive species (S(VI), Mn(II) and Fe(II)) and alkalinity were measured.
Starting oxygen saturation was about 80% within the chamber. After 7 days, anoxia was established in the bottom waters within the chambers. Mn(II) and Fe(II) started diffusing towards the anoxic water column until they reached the surficial sediment. Being reoxidized there, Mn and Fe reprecipitated, giving a rusty coloration to the seafloor. Infaunal species appeared at the sediment surface. After 20 days, all macro-organisms were dead. Decomposition of macro-organisms at the sediment–water interface generated S(-II) within the entire height of the chamber, leading to a downward flux of sulfides into the sediment, where they were quickly oxidized by metallic oxides or precipitated as FeS. S(-II) was below detection in the water column and pore waters at the end of the experiment. Our results suggest that S(-II) enrichment in the water column of coastal systems, which are episodically anoxic, is strongly controlled by the biomass of benthic macrofauna and its decay during anoxia, whereas its residence time in the water column is controlled by iron availability (as solid oxides or as dissolved reduced cations) within the sediment, even without water circulation.
Keywords: Adriatic Sea, marine sediments, anoxia, Northern Adriatic
Published in DiRROS: 02.08.2024; Views: 2; Downloads: 8
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32. GoMapMan : integration, consolidation and visualization of plant gene annotations within the MapMan ontologyŽiva Ramšak, Špela Baebler, Ana Rotter, Matej Korbar, Igor Mozetič, Björn Usadel, Kristina Gruden, 2014, original scientific article Abstract: GoMapMan (http://www.gomapman.org) is an open web-accessible resource for gene functional annotations in the plant sciences. It was developed to facilitate improvement, consolidation and visualization of gene annotations across several plant species. GoMapMan is based on the MapMan ontology, organized in the form of a hierarchical tree of biological concepts, which describe gene functions. Currently, genes of the model species Arabidopsis and three crop species (potato, tomato and rice) are included. The main features of GoMapMan are (i) dynamic and interactive gene product annotation through various curation options; (ii) consolidation of gene annotations for different plant species through the integration of orthologue group information; (iii) traceability of gene ontology changes and annotations; (iv) integration of external knowledge about genes from different public resources; and (v) providing gathered information to high throughput analysis tools via dynamically generated export files. All of the GoMapMan functionalities are openly available, with the restriction on the curation functions, which require prior registration to ensure traceability of the implemented changes.
Keywords: genes, plants
Published in DiRROS: 02.08.2024; Views: 6; Downloads: 3
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34. Temperature dependence of planktonic metabolism in the subtropical North Atlantic OceanL.S. Garcia-Corral, E. Barber, A. Regaudie-de_Gioux, S. Sal, J.M. Holding, S. Agusti, N. Navarro, P. Serret, Patricija Mozetič, Carlos M. Duarte, 2014, original scientific article Abstract: The temperature dependence of planktonic metabolism in the subtropical North Atlantic Ocean was assessed on the basis of measurements of gross primary production (GPP), community respiration (CR) and net community production (NCP), as well as experimental assessments of the response of CR to temperature manipulations. Metabolic rates were measured at 68 stations along three consecutive longitudinal transects completed during the Malaspina 2010 Expedition, in three different seasons. Temperature gradients were observed in depth and at basin and seasonal scale. The results showed seasonal variability in the metabolic rates, the highest rates being observed during the spring transect. The overall mean integrated GPP / CR ratio was 1.39 ± 0.27 decreasing from winter to summer, and the NCP for the subtropical North Atlantic Ocean during the cruises exhibits net autotrophy (NCP > 0) in about two-thirds (66%) of the total sampled communities. Also, we reported the activation energies describing the temperature dependence of planktonic community metabolism, which was generally higher for CR than for GPP in the subtropical North Atlantic Ocean, as the metabolic theory of ecology predicts. Furthermore, we made a comparison of activation energies describing the responses to in situ temperature in the field (EaCR = 1.64 ± 0.36 eV) and those derived experimentally by temperature manipulations (EaCR = 1.45 ± 0.6 eV), which showed great consistency.
Keywords: morje, plankton, fitoplankton, klorofil, trofični status, anoksije
Published in DiRROS: 01.08.2024; Views: 28; Downloads: 26
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35. Meiofauna winners and losers of coastal hypoxia: case study harpacticoid copepodsMateja Grego, Bettina Riedel, Michael Stachowitsch, Marleen De Troch, 2014, original scientific article Abstract: The impact of anoxia on meiobenthic copepod species was assessed by means of a field experiment. Four plexiglass chambers were deployed in situ in 24 m depth to simulate an anoxic event of 9 days, 1 month, 2 months and 10 months. From normoxic to anoxic conditions, we recorded a drop in copepod density and species richness. With increasing duration of anoxia the relative abundance of the individuals of the family Cletodidae increased, and they survived the 1 month and 2 month anoxia, the latter with few specimens. They were the true "winners" of the experimentally induced anoxia. Dominance did not increase in the deployments because not one, but several species from this family were tolerant to anoxia. The overall rate of survival was the same for males and females, but no juvenile stages of copepods survived in anoxia. During a recovery phase of 7 days after a short-term anoxia of 9 days, harpacticoid copepod density did not increase significantly, and there was only a slight increase in species diversity. We concluded that no substantial colonisation from the surrounding sediment took place. The survivors, however, showed a high potential for recovery according to the number of gravid females, whose number increased significantly once the oxygen was available again. These findings imply that substantial energy is allocated to reproduction in the recovery phase.
Published in DiRROS: 01.08.2024; Views: 33; Downloads: 22
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36. Salicylic acid is an indispensable component of the Ny-1 resistance-gene-mediated response against Potato virus Y infection in potatoŠpela Baebler, Kamil Witek, Marko Petek, Katja Stare, Magda Tušek-Žnidarič, Maruša Pompe Novak, Jenny Renaut, K. Szajko, D. Strzelczyk-Żyta, W. Marczewski, Karolina Morgiewicz, Kristina Gruden, Jacek Hennig, 2014, original scientific article Abstract: The purpose of the study was to investigate the role of salicylic acid (SA) signalling in Ny-1-mediated hypersensitive resistance (HR) of potato (Solanum tuberosum L.) to Potato virus Y (PVY). The responses of the Ny-1 allele in the Rywal potato cultivar and transgenic NahG-Rywal potato plants that do not accumulate SA were characterized at the cytological, biochemical, transcriptome, and proteome levels. Analysis of noninoculated and inoculated leaves revealed that HR lesions started to develop from 3 d post inoculation and completely restricted the virus spread. At the cytological level, features of programmed cell death in combination with reactive oxygen species burst were observed. In response to PVY infection, SA was synthesized de novo. The lack of SA accumulation in the NahG plants led to the disease phenotype due to unrestricted viral spreading. Grafting experiments show that SA has a critical role in the inhibition of PVY spreading in parenchymal tissue, but not in vascular veins. The whole transcriptome analysis confirmed the central role of SA in orchestrating Ny-1-mediated responses and showed that the absence of SA leads to significant changes at the transcriptome level, including a delay in activation of expression of genes known to participate in defence responses. Moreover, perturbations in the expression of hormonal signalling genes were detected, shown as a switch from SA to jasmonic acid/ethylene signalling. Viral multiplication in the NahG plants was accompanied by downregulation of photosynthesis genes and activation of multiple energy-producing pathways.
Keywords: plant-pathogen interactions, Potato virus Y, salicylic acid, whole transcriptome analysis
Published in DiRROS: 01.08.2024; Views: 34; Downloads: 22
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38. Turbulence observations in the Gulf of Trieste under moderate wind forcing and different water column stratificationFrancesco Marcello Falcieri, Lakshmi Kantha, Alvise Benetazzo, Andrea Bergamasco, Davide Bonaldo, Francesco Barbariol, Vlado Malačič, Mauro Sclavo, S. Carniel, 2016, original scientific article Abstract: The oceanographic campaign CARPET2014 (Characterizing Adriatic Region Preconditionig EvenTs), (30 January–4 February 2014) collected the very first turbulence data in the Gulf of Trieste (northern Adriatic Sea) under moderate wind (average wind speed 10 m s−1) and heat flux (net negative heat flux ranging from 150 to 400 W m−2). Observations consisted of 38 CTD (Conductivity, Temperature, Depth) casts and 478 microstructure profiles (grouped into 145 ensembles) with three sets of yoyo casts, each lasting for about 12 consecutive hours. Averaging closely repeated casts, such as the ensembles, can lead to a smearing effect when in the presence of a vertical density structure with strong interfaces that can move up or down between subsequent casts under the influence of tides and internal waves. In order to minimize the smearing effect of such displacements on mean quantities, we developed an algorithm to realign successive microstructure profiles to produce sharper and more meaningful mean profiles of measured turbulence parameters.
During the campaign, the water column in the gulf evolved from well-mixed to stratified conditions due to Adriatic waters intruding at the bottom along the gulf's south-eastern coast. We show that during the warm and relatively dry winter, the water column in the Gulf of Trieste, even under moderate wind forcing, was not completely mixed due to the influence of bottom waters intruding from the open sea. Inside the gulf, two types of water intrusions were found during yoyo casts: one coming from the northern coast of the Adriatic Sea (i.e. cooler, fresher and more turbid) and one coming from the open sea in front of the Po Delta (i.e. warmer, saltier and less turbid). The two intrusions had different impacts on turbulence kinetic energy dissipation rate profiles. The former, with high turbidity, acted as a barrier to wind-driven turbulence, while the latter, with low sediment concentrations and a smaller vertical density gradient, was not able to suppress downward penetration of turbulence from the surface.
Keywords: hydrology, oceanographic data, numerical modelling, wind forcing, turbulence
Published in DiRROS: 01.08.2024; Views: 28; Downloads: 26
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39. Protein gas vesicles of bacillus megaterium as enhancers of ultrasound-induced transcriptional regulationVid Jazbec, Nina Varda, Ernest Šprager, Maja Meško, Sara Vidmar, Rok Romih, Marjetka Podobnik, Andreja Kežar, Roman Jerala, Mojca Benčina, 2024, original scientific article Published in DiRROS: 01.08.2024; Views: 40; Downloads: 29
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40. Evaluation of cyanobacteria biomass derived from upgrade of phycocyanin fluorescence estimationTinkara Rozina, Bojan Sedmak, Maja Zupančič Justin, Andrej Meglič, 2017, original scientific article Abstract: The number of harmful cyanobacterial blooms has increased significantly at the global level in recent years. One of the characteristics of cyanobacteria that gives them advantage over other phytoplankton organisms are auxiliary photosynthetic pigments, such as phycocyanin. This fluorescent pigment emits light at a different wavelength as chlorophyll and can therefore be used for detection of cyanobacteria in situ. In this study we used submersible phycocyanin fluorescence sensors and compare their voltage output to concentration of extracted phycocyanin, cell counts and biovolume. The relation was linear in all three cases; however, the variability of regression line slopes between different cyanobacteria strains was high in the case of PC extract concentration and cell count. The highest uniformity in the linear fits was between fluorescence signal and biovolume therefore making it the best candidate for fluorescence sensor voltage output conversion. In the context of this work we also compared different methods for PC extraction. Modifying the equations by subtracting the absorption at 750 nm almost entirely reduces the false PC concentration estimation due to sample turbidity.
Keywords: fluorescence measurements, phycocyanin, cyanobacteria
Published in DiRROS: 01.08.2024; Views: 39; Downloads: 14
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