1. Living inside a jellyfish : the symbiosis case study of host-specialized dinoflagellates, “Zooxanthellae”, and the Scyphozoan Cotylorhiza tuberculataAngélica Enrique- Navarro, Emma Huertas, Vesna Flander-Putrle, Ana Bartual, Gabriel Navarro, Javier Ruiz, Alenka Malej, Laura Prieto, 2022, izvirni znanstveni članek Povzetek: The photosymbiosis with host-specific dinoflagellates is a widespread relationship in marine organisms. Despite the evidenced biodiversity of this kind of mutualism, most research focuses on the study of scleractinian corals, and there is a lack of knowledge about other symbiotic cnidarians such as jellyfishes. The Mediterranean jellyfish Cotylorhiza tuberculata (Rhizostomae, Scyphozoa) harbors an endosymbiotic dinoflagellate of the family Symbiodiniaceae. In this study, we examine the algae distribution within the host body as well as, the pigment content and cell density of the symbiont. Furthermore, the size, morphology and fluorescence of cultured symbionts were studied under light microscopy, Imaging Flow Cytometry (IFC), and Scanning Electron Microscopy (SEM). The C:N composition and optical properties of the medusa tissue were measured to evaluate their role in the symbiosis. The medusae body was divided into two different sections to investigate the distribution of symbionts in hospite: oral arms (OA) and umbrella (UM). C:N composition of C. tuberculata was and symbiont density was significantly higher in the OA section. Mean chlorophyll a concentration of the algae was 1.33 (± 0.83) pg Chl a cell–1. The study of the pigment composition by HPLC (High Performance Liquid Chromatography), revealed the presence of 13 different pigments, being the most representative chlorophyll a, chlorophyll c2, and peridinin typical pigments of Symbiodiniaceae. Cell diameter of algae freshly isolated from the host was 8.71 ± 0.97 μm and cell growth rate was 0.52 (± 0.09) 106 cell ml–1 d–1. The presence of vegetative coccoid cells, doublet and motile mastigotes were revealed within the Symbiodiniaceae cultures. A calcifying matrix typical of Symbiodiniaceae and formed in partner with bacteria, was also observed most cultures. The umbrella tissue of the medusa absorbed at ultraviolet radiation (UVR) region, suggesting that medusae tissue protects photosymbionts from the negative effect of the high energetic UVR and attenuates the light intensity reaching algae inside the host. The presence of a dense Symbiodiniaceae population and the protection to UVR and elevated environmental irradiance provided by medusae tissue, maintain symbionts in optimal light conditions for photosynthesis and may be a reason added to explain the population success of Cotylorhiza tuberculata.
Ključne besede: HPLC, SEM microscopy, absorbance, photosymbiosis
Objavljeno v DiRROS: 16.07.2024; Ogledov: 5; Prenosov: 5
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2. Phytoplankton pigments reveal size structure and interannual variability of the coastal phytoplankton community (Adriatic Sea)Vesna Flander-Putrle, Janja Francé, Patricija Mozetič, 2022, izvirni znanstveni članek Povzetek: In coastal seas, a variety of environmental variables characterise the average annual pattern of the physico-chemical environment and influence the temporal and spatial variations of phytoplankton communities. The aim of this study was to track the annual and interannual variability of phytoplankton biomass in different size classes in the Gulf of Trieste (Adriatic Sea) using phytoplankton pigments. The seasonal pattern of phytoplankton size classes showed a co-dominance of the nano and micro fractions during the spring peak and a predominance of the latter during the autumn peak. The highest picoplankton values occurred during the periods with the lowest total phytoplankton biomass, with chlorophytes dominating during the colder months and cyanobacteria during the summer. The highest number of significant correlations was found between phytoplankton taxa and size classes and temperature, nitrate and nitrite. The most obvious trend observed over the time series was an increase in picoplankton in all water layers, with the most significant trend in the bottom layer. Nano- and microplankton showed greater variation in biomass, with a decrease in nanoplankton biomass in 2011 and 2012 and negative trend in microplankton biomass in the bottom layer. These results suggest that changes in trophic relationships in the pelagic food web may also have implications for biogeochemical processes in the coastal sea.
Ključne besede: phytoplankton, biomass, phytoplankton size classes, phytoplankton pigments, HPLC, interannual variability, trends, Adriatic Sea
Objavljeno v DiRROS: 16.07.2024; Ogledov: 28; Prenosov: 7
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3. Vsebnost ekstraktivov v skorji in lesu robinije (Robinia pseudoacacia l.)Viljem Vek, Blaž Vivod, Ida Poljanšek, Primož Oven, 2019, izvirni znanstveni članek Povzetek: Raziskali smo vsebnost in sestavo ekstraktivov v lesnih tkivih in skorji robinije (Robinia pseudoacacia L.). Vzorce njenega lesa in skorje smo ekstrahirali v aparatu Soxhlet z acetonom. Acetonske ekstrakte smo preiskali gravimetrično in s tem izmerili vsebnost skupnih hidrofilnih ekstraktivov. Z UV-Vis spektrofotometrom smo kolorimetrično izmerili vsebnost skupnih fenolov. Ekstrakte lesa in skorje robinije smo nato detajlno preiskali s sistemom za tekočinsko kromatografijo visoke ločljivosti (HPLC). S to tehniko smo v ekstraktih identificirali in kvantitativno ovrednotili dihidrorobinetin. Največje vsebnosti skupnih hidrofilnih ekstraktivov, skupnih fenolov in dihidrorobinetina smo izmerili v vzorcih jedrovine. Značilno manj ekstraktivov je bilo v vzorcih beljave in skorje. Aksialne variabilnosti v vsebnosti topnih komponent za les in skorjo robinije nismo dognali. Ugotovili smo, da je jedrovina robinije bogat vir fenolnih ekstraktivov.
Ključne besede: robinija, ekstraktivi, HPLC, dragocene spojine, biorafinarije
Objavljeno v DiRROS: 10.10.2019; Ogledov: 4960; Prenosov: 3430
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4. Razvoj metode za HPLC-analizo izbranih fenolnih spojin lesaIda Poljanšek, Viljem Vek, Primož Oven, 2015, izvirni znanstveni članek Povzetek: Preučevali smo vpliv sestave mobilne faze na ločitev enostavnih fenolnih spojin, kot so galna kislina, pirokatehol, floroglucinol, resorcinol, vanilin in flavonoida katehina s tekočinsko kromatografijo visoke ločljivosti (HPLC). Kot najbolj primerna metoda za ločitev komponent se je izkazala metoda gradientnega izpiranja s programiranim spreminjanjem sestave mobilne faze acetonitril in 2-odstotna vodna raztopina mravljinčne kisline od 2 : 98 do 25 : 75. Ločitev organskih spojin je bila učinkovitejša v mobilni fazi z manjšim deležem mravljinčne kisline. HPLC je primerna metoda za identifikacijo in kvantitativno analizo spojin v različnih tipih vzorcev na širokem področju verige gozdarstva, lesarstva in papirništva.
Ključne besede: les, ekstraktivi, fenolne spojine, katehin, kromatografija, HPLC, ločba
Objavljeno v DiRROS: 12.07.2017; Ogledov: 4999; Prenosov: 2354
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