1091. Respiration rates in shallow lakes of different types : contribution of benthic microorganisms, macrophytes, plankton and macrozoobenthosJanusz Żbikowski, Tatjana Simčič, Franja Pajk, Małgorzata Poznańska-Kakareko, Tomasz Kakareko, Jarosław Kobak, 2019, original scientific article Abstract: The determination of the metabolic activity of organisms at various trophic levels is crucial for the proper assessment of the energy flow through the ecosystem, which is the basic process determining ecosystem functioning. We estimated the respiration rate in nine shallow, eutrophic lakes (macrophyte-dominated and phytoplankton-dominated) from north-eastern Poland. Respiratory carbon loss (RCL) through bottom microbial communities, macrophytes, plankton and macrozoobenthos was estimated by measuring the Electron Transport System activity. The shares of the particular ecosystem components in respiration processes differed among the lake types and seasons. The bottom microbial communities contributed most to the RCL (from 50% in the macrophyte-dominated lakes to 90% in the shallower phytoplankton-dominated lakes) except in macrophytes-dominated lakes in summer, where the macrophyte contribution prevailed (80%). The contribution of plankton was considerable only in the deeper phytoplankton-dominated lakes (20%). Macrozoobenthos was important (20%) only in the macrophyte-dominated lakes in spring and autumn. The RCL through bottom microbial communities was substantially higher in the shallow lakes (especially phytoplankton-dominated) than in deep, stratified eutrophic lakes. Shallow eutrophic lakes can be highly productive due to intensive organic matter mineralization at the bottom and rapid flow and cycling of carbon and nutrients resulting from their polymictic character.
Keywords: shallow lakes, ETS activity, respiratory carbon loss, abiotic parameters
Published in DiRROS: 23.07.2024; Views: 269; Downloads: 229
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1093. A decline in molluscan carbonate production driven by the loss of vegetated habitats encoded in the Holocene sedimentary record of the Gulf of TriesteAdam Tomašových, Ivo Gallmetzer, Alexandra Haselmair, Darrell S. Kaufman, Borut Mavrič, Martin Zuschin, 2019, original scientific article Abstract: Carbonate sediments in non-vegetated habitats on the north-east Adriatic shelf are dominated by shells of molluscs. However, the rate of carbonate molluscan production prior to the 20th century eutrophication and overfishing on this and other shelves remains unknown because: (i) monitoring of ecosystems prior to the 20th century was scarce; and (ii) ecosystem history inferred from cores is masked by condensation and mixing. Here, based on geochronological dating of four bivalve species, carbonate production during the Holocene is assessed in the Gulf of Trieste, where algal and seagrass habitats underwent a major decline during the 20th century. Assemblages of sand-dwelling Gouldia minima and opportunistic Corbula gibba are time-averaged to >1000 years and Corbula gibba shells are older by >2000 years than shells of co-occurring Gouldia minima. This age difference is driven by temporally disjunct production of two species coupled with decimetre-scale mixing. Stratigraphic unmixing shows that Corbula gibba declined in abundance during the highstand phase and increased again during the 20th century. In contrast, one of the major contributors to carbonate sands – Gouldia minima – increased in abundance during the highstand phase, but declined to almost zero abundance over the past two centuries. Gouldia minima and herbivorous gastropods associated with macroalgae or seagrasses are abundant in the top-core increments but are rarely alive. Although Gouldia minima is not limited to vegetated habitats, it is abundant in such habitats elsewhere in the Mediterranean Sea. This live–dead mismatch reflects the difference between highstand baseline communities (with soft-bottom vegetated zones and hard-bottom Arca beds) and present-day oligophotic communities with organic-loving species. Therefore, the decline in light penetration and the loss of vegetated habitats with high molluscan production traces back to the 19th century. More than 50% of the shells on the sea floor in the Gulf of Trieste reflect inactive production that was sourced by heterozoan carbonate factory in algal or seagrass habitats.
Keywords: bioturbation, carbonate production, mollusca, northern Adriatic Sea, taphonomy, time averaging
Published in DiRROS: 23.07.2024; Views: 234; Downloads: 174
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1094. Genetic characterisation of European mudminnow (Umbra krameri) populations from the Sava River systemSaša Marić, David Stanković, Radek Šanda, Marko Ćaleta, Srećko Čolić, Goran Šukalo, Aleš Snoj, 2019, original scientific article Abstract: Two new populations of the European mudminnow (Umbra krameri Walbaum, 1792) were discovered in the Sava River system, one in its middle part (Bosnia and Herzegovina) and the other in a tributary to the Kupa River (Croatia). The Croatian population is the most upstream mudminnow discovery in the Sava River system known to date. The genetic structure of the newly recorded mudminnow populations was examined using mitochondrial DNA and microsatellite loci. By adding these new populations to the analysis of the population genetic structure of mudminnow from the Sava River system, previously unresolved relationships between the populations from the upper and the lower Sava were clarified: the middle Sava populations were shown to be well outside the hybridisation zone with the Danubian clade, meaning the upstream boundary of this zone is confined to the lower Sava. The results also suggest that mudminnow populations in the Sava River system are less isolated than previously believed. Namely, intermediate gene-flow was detected when comparing the uppermost Sava population with the lower Sava populations. Taking these results into account, appropriate guidelines are proposed to preserve mudminnow populations from the Sava River system.
Published in DiRROS: 23.07.2024; Views: 287; Downloads: 152
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1095. Y2O3-Al2O3 microsphere crystallization analyzed by electron backscatter diffraction (EBSD)Wolfgang Wisniewski, Anna Prnová, Peter Švančárek, Milan Parchovianský, Dušan Galusek, 2020, original scientific article Abstract: The crystallization of glass microspheres in the Y2O3–Al2O3-system produced from precursor powders of four different nominal compositions via flame synthesis is analyzed in detail by electron microscopy with a focus on electron backscatter diffraction (EBSD). Growth models are formulated for individual microspheres crystallized during flame synthesis as well as after an additional heat treatment step. 16 different types of crystallized bodies are cataloged for future reference. They are presented without regard for their relative occurrence; some are extremely rare but illustrate the possibilities of flame synthesis in the analyzed system. All three phases in the binary Y2O3–Al2O3-phase diagram (Y3Al5O12, YAlO3 and Y4Al2O9) and α-alumina are located by EBSD. Energy dispersive X-ray spectrometry results obtained from these microspheres show that their chemical composition can deviate from the nominal composition of the precursor powder. The multitude of differing microsphere types showing polygon and dendritic crystal growth as well as phase separation indicate that flame synthesis can lead to a wide variety of parameters during microsphere production, e.g. via irregular flight paths through the flame, contaminants or irregular cooling rates.
Keywords: Y2O3-Al2O3, microsphere crystallization, flame synthesis, EBSD
Published in DiRROS: 23.07.2024; Views: 253; Downloads: 190
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1096. Natural variation in Arabidopsis thaliana rosette area unveils new genes involved in plant developmentEdgardo Brigatti, Rubén González, Anamarija Butković, Mark Paul Selda Rivarez, Santiago F. Elena, 2020, original scientific article Abstract: Growth is a complex trait influenced by multiple genes that act at different moments during the development of an organism. This makes it difficult to spot its underlying genetic mechanisms. Since plant growth is intimately related to the effective leaf surface area (ELSA), identifying genes controlling this trait will shed light on our understanding of plant growth. To find new genes with a significant contribution to plant growth, here we used the natural variation in Arabidopsis thaliana to perform a genome-wide association study of ELSA. To do this, the projected rosette area of 710 worldwide distributed natural accessions was measured and analyzed using the genome-wide efficient mixed model association algorithm. From this analysis, ten genes were identified having SNPs with a significant association with ELSA. To validate the implication of these genes into A. thaliana growth, six of them were further studied by phenotyping knock-out mutant plants. It was observed that rem1.2, orc1a, ppd1, and mcm4 mutants showed different degrees of reduction in rosette size, thus confirming the role of these genes in plant growth. Our study identified genes already known to be involved in plant growth but also assigned this role, for the first time, to other genes.
Published in DiRROS: 23.07.2024; Views: 271; Downloads: 184
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1097. Genotoxic effects of cylindrospermopsin, microcystin-LR and their binary mixture in human hepatocellular carcinoma (HepG2) cell lineLeticia Díez-Quijada, Klara Hercog, Martina Štampar, Metka Filipič, Ana M. Cameán, Angeles Jos, Bojana Žegura, 2020, original scientific article Abstract: Simultaneous occurrence of cylindrospermopsin (CYN) and microcystin-LR (MCLR) has been reported in the aquatic environment and thus human exposure to such mixtures is possible. As data on the combined effects of CYN/MCLR are scarce, we aimed to investigate the adverse effects related to genotoxic activities induced by CYN (0.125, 0.25 and 0.5 µg/mL) and MCLR (1 µg/mL) as single compounds and their combinations in HepG2 cells after 24 and 72 h exposure. CYN and CYN/MCLR induced DNA double-strand breaks after 72 h exposure, while cell cycle analysis revealed that CYN and CYN/MCLR arrested HepG2 cells in G0/G1 phase. Moreover, CYN and the combination with MCLR upregulated CYP1A1 and target genes involved in DNA-damage response (CDKN1A, GADD45A). Altogether, the results showed that after 72 h exposure genotoxic activity of CYN/MCLR mixture was comparable to the one of pure CYN. On the contrary, MCLR (1 µg/mL) had no effect on the viability of cells and had no influence on cell division. It did not induce DNA damage and did not deregulate studied genes after prolonged exposure. The outcomes of the study confirm the importance of investigating the combined effects of several toxins as the effects can differ from those induced by single compounds.
Published in DiRROS: 23.07.2024; Views: 258; Downloads: 203
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1098. IGF-binding proteins 3 and 4 are regulators of sprouting angiogenesisMarchien G. Dallinga, Yasmin I. Habani, Richelle P. Kayser, Cornelis J. F. van Noorden, Ingeborg Klaassen, Reinier O. Schlingemann, 2020, original scientific article Abstract: Purpose
We have previously identified insulin-like growth factor 2 (IGF2) and insulin-like growth factor 1 receptor (IGF1R) as essential proteins for tip cell maintenance and sprouting angiogenesis. In this study, we aim to identify other IGF family members involved in endothelial sprouting angiogenesis.
Methods
Effects on sprouting were analyzed in human umbilical vein endothelial cells (HUVECs) using the spheroid-based sprouting model, and were quantified as mean number of sprouts per spheroid and average sprout length. RNA silencing technology was used to knockdown gene expression. Recombinant forms of the ligands (IGF1 and IGF2, insulin) and the IGF-binding proteins (IGFBP) 3 and 4 were used to induce excess effects. Effects on the tip cell phenotype were analyzed by measuring the fraction of CD34+ tip cells using flow cytometry and immunohistochemistry in a 3D angiogenesis model. Experiments were performed in the presence and absence of serum.
Results
Knockdown of IGF2 inhibited sprouting in HUVECs, in particular when cultured in the absence of serum, suggesting that components in serum influence the signaling of IGF2 in angiogenesis in vitro. We then determined the effects of IGFBP3 and IGFBP4, which are both present in serum, on IGF2-IGF1R signaling in sprouting angiogenesis in the absence of serum: knockdown of IGFBP3 significantly reduced sprouting angiogenesis, whereas knockdown of IGFBP4 resulted in increased sprouting angiogenesis in both flow cytometry analysis and immunohistochemical analysis of the 3D angiogenesis model. Other IGF family members except INSR did not affect IGF2-IGF1R signaling.
Conclusions
Serum components and IGF binding proteins regulate IGF2 effects on sprouting angiogenesis. Whereas IGFBP3 acts as co-factor for IGF2-IGF1R binding, IGFBP4 inhibits IGF2 signaling.
Keywords: Angiogenesis, tip cells, IGF2, IGF binding proteins, endothelial cells, cultured cells, endothelial growth factors
Published in DiRROS: 23.07.2024; Views: 265; Downloads: 204
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1099. Multiannual trend of micro-pollutants in sediments and benthic community response in a Mediterranean lagoon (Sacca di Goro, Italy)Valentina Pitacco, Michele Mistri, Carla Rita Ferrari, Adriano Sfriso, Andrea Augusto Sfriso, Cristina Munari, 2020, original scientific article Abstract: Long-term variations of ecological status in a Mediterranean coastal lagoon (Sacca di Goro, Northern Adriatic) were investigated, combining data on the concentration of surface sediment contaminants and on the structure of the macrobenthic community. The aim was to assess any amount of chemical contamination and check the response of the macrobenthic community to sediment contamination. Over the studied period, the sediments of the lagoon showed contamination by trace metals and organochlorine pesticides, with most of them exceeding the thresholds indicated by the Italian legislation in many samples. Contamination by polychlorinated dibenzodioxins and dibenzofurans (PCDD/Fs) and polycyclic aromatic hydrocarbons (PAHs) instead never exceeded the threshold. The ecological status based on the macrobenthic community, evaluated through biotic indices (AMBI and M-AMBI), fell below the Good/Moderate threshold in most samples. The results indicate a possible influence of toxic compounds in sediment on benthic organisms, but most of the variability shown by the macrobenthic community is probably due to other factors. The difficulty in establishing a cause/effect relationship was due to the co-occurrence and variability of various stressors (both natural and anthropogenic) and their interactions. The methods currently used for monitoring transitional waters thus seem insufficient to disentangle the effect of pollutants and other environmental variables on the benthos. Integrated approaches (e.g., bioaccumulation and toxicity tests) are thus needed for a more precise identification of the risk posed by a high concentration of pollutants in such environments.
Keywords: coastal lagoon, macrobenthos, trace elements, organochlorine pesticides, PAHs, PCDD/Fs
Published in DiRROS: 23.07.2024; Views: 272; Downloads: 231
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1100. Poor perfusion of the microvasculature in peritoneal metastases of ovarian cancerArnoud W. Kastelein, Laura M.C. Vos, Juliette O. A. M. van Baal, Jasper J. Koning, Vashendriya V. V. Hira, Rienk Nieuwland, Willemien J. van Driel, Zühre Uz, Thomas M van Gulik, Jacco van Rheenen, Can Ince, Jan-Paul W.R. Roovers, Cornelis J. F. van Noorden, Christianne A. R. Lok, 2020, original scientific article Abstract: Most women with epithelial ovarian cancer (EOC) suffer from peritoneal carcinomatosis upon first clinical presentation. Extensive peritoneal carcinomatosis has a poor prognosis and its pathophysiology is not well understood. Although treatment with systemic intravenous chemotherapy is often initially successful, peritoneal recurrences occur regularly. We hypothesized that insufficient or poorly-perfused microvasculature may impair the therapeutic efficacy of systemic intravenous chemotherapy but may also limit expansive and invasive growth characteristic of peritoneal EOC metastases. In 23 patients with advanced EOC or suspicion thereof, we determined the angioarchitecture and perfusion of the microvasculature in peritoneum and in peritoneal metastases using incident dark field (IDF) imaging. Additionally, we performed immunohistochemical analysis and 3-dimensional (3D) whole tumor imaging using light sheet fluorescence microscopy of IDF-imaged tissue sites. In all metastases, microvasculature was present but the angioarchitecture was chaotic and the vessel density and perfusion of vessels was significantly lower than in unaffected peritoneum. Immunohistochemical analysis showed expression of vascular endothelial growth factor and hypoxia inducible factor 1α, and 3D imaging demonstrated vascular continuity between metastases and the vascular network of the peritoneum beneath the elastic lamina of the peritoneum. We conclude that perfusion of the microvasculature within metastases is limited, which may cause hypoxia, affect the behavior of EOC metastases on the peritoneum and limit the response of EOC metastases to systemic treatment.
Keywords: microvasculature, microcirculation, EOC, peritoneal carcinomatosa, incident dark feld imaging
Published in DiRROS: 23.07.2024; Views: 285; Downloads: 224
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