University of Dubrovnik

About: University of Dubrovnik is a education organization based out in Dubrovnik, Croatia. It is known for research contribution in the topics: Population & Tourism. The organization has 351 authors who have published 954 publications receiving 7126 citations. The organization is also known as: University Durbrovnik.

Microsphere packages of carotenoids: intact sea urchin eggs tracked by Raman spectroscopy tools

Abstract: Although natural exposure to ambient UV radiation in oligotrophic seawater at small depths can reach the levels responsible for cellular damage, the sea urchin Paracentrotus lividus is frequently in such sites, particularly on the southern Adriatic Sea shore. Spawning their eggs and spending their early life stage in rocky shores at depths of 0.5–2 m are the results of their successful adaptation strategies, although adults may dwell at greater depths. Surprisingly, there is a paucity of reports regarding the carotenoid content in sea urchin eggs. Beyond their important role in photoprotection against high UV exposure, cell division and early development, the content and distribution of carotenoids contribute to the successful survival of sea urchins and also determine the color of their gonads (roe), which is of commercial importance as a delicacy. Herein, for the first time, we have described the carotenoid content and distribution in intact, freshly released eggs of P. lividus species, non-destructively employing resonance Raman spectroscopy and imaging; near-infrared Raman spectroscopy revealed additional molecular carotenoid content. Echinenone and β-carotene resonance Raman signals were the most intense, and they were identified as the principal carotenoids that are preferentially accumulated in eggs rather than in gonads. Raman imaging in confocal mode revealed the uniform distribution of the carotenoid signal over the whole eggs, while the distribution of proteins appeared spotted. Egg carotenoids generally maintained their identity after 2 months of dry storage, with slight signs of CC bond oxidation. The potential utilization of P. lividus sea urchin eggs as valuable microsphere packages of native carotenoids is discussed.

Record of a live sharksucker, Echeneis naucrates (Osteichthyes: Echeneidae) from the south-eastern Adriatic (Croatian coast)

Abstract: On 23 July 2007 a very rare specimen of the live sharksucker Echeneis naucrates was caught in the Ombla River near Dubrovnik, in the south-eastern Adriatic. First data on biometric lengths and morphology of this species are presented for the eastern Adriatic.

Improved Model for Estimation of Spatial Averaging Path Length

Abstract: In mobile communication systems, the transmitted RF signal is subject to mutually independent deterministic path loss and stochastic multipath and shadow fading. As at each spatial location mostly the composite signal samples are measured, their components are distinguished by averaging out the multipath-caused signal level variations, while preserving just the ones due to shadowing. The prerequisite for this is the appropriateness of the local area averaging path length that enables obtaining the local mean (composed of mean path loss and shadow fading) and the multipath fading as difference between the composite signal sample and the local mean. However, the so far reported analytical approaches to estimation of the averaging path length are based on considering either the multipath or just the shadow fading, with applicability limited to only specific topologies and frequencies. Therefore, in this paper, the most widely used Lee analytical method is generalized and improved by considering multipath and shadowing concurrently, so providing the general closed-form elementary-function based estimation of the optimal averaging path length as a function of common multipath and shadow fading parameters characterizing particular propagation environment. The model enables recommendations for the optimal averaging length for all propagation conditions facing the mobile receiver.

Impact of environmental conditions on phospholipid fatty acid composition: implications from two contrasting estuaries

Abstract: Phospholipid (PL) composition has a tremendous influence on the cell integrity and physiological competency. At the same time, plankton PL make important metabolic fuels for higher trophic levels. The goal of this study was to identify environmental control on PL production and their molecular identity of the suspended particles in two different estuaries. We conducted research in subtropical, eutrophic Wenchang River Estuary in China and temperate pristine, mesotrophic Krka River Estuary in Croatia. In agreement with the more abundant phytoplankton, PL concentrations were much higher in the Wenchang River Estuary (30.3–178.2 μg L−1) than in the Krka River Estuary (8.4–18.8 μg L−1). Given that six PL classes investigated (phosphatidylcholine (PC), phosphatidylglycerol (PG), phosphatidylethanolamine (PE), phosphatidic acid (PA), phosphatidylinositol (PI), and phosphatidylserine (PS)) have different roles in the cell, we expected their different fatty acid composition in different environments. We found small differences in the fatty acid composition of PC, PG, and PI between two estuaries. These results suggest that the essential fatty acid compositions of these PL in estuarine plankton are relatively constant in order to preserve membrane functions and/or cell processes in which they are involved regardless of environmental conditions. In contrast, PE, PA and PS fatty acid composition substantially differed between two estuaries as well as throughout the salinity gradient in each estuary. This suggests the adaptability of plankton to remodel these PL depending on the environmental conditions and the plankton community structure. Good environmental conditions (favorable N/P ratio, temperature) are important for increased PL content (% in POC and total lipids) in estuarine plankton and increased essential polyunsaturated fatty acid content in PL, which is beneficial to higher trophic levels.