1. Extremophilic microorganisms in Central EuropeVera Zgonik, Janez Mulec, Tina Eleršek, Nives Ogrinc, Polona Jamnik, Nataša Poklar Ulrih, 2021, pregledni znanstveni članek Povzetek: Extremophiles inhabit a wide variety of environments. Here we focus on extremophiles in moderate climates in central Europe, and particularly in Slovenia. Although multiple types of stress often occur in the same habitat, extremophiles are generally combined into groups according to the main stressor to which they are adapted. Several types of extremophiles, e.g., oligotrophs, are well represented and diverse in subsurface environments and karst regions. Psychrophiles thrive in ice caves and depressions with eternal snow and ice, with several globally distributed snow algae and psychrophilic bacteria that have been discovered in alpine glaciers. However, this area requires further research. Halophiles thrive in salterns while thermophiles inhabit thermal springs, although there is little data on such microorganisms in central Europe, despite many taxa being found globally. This review also includes the potential use of extremophiles in biotechnology and bioremediation applications.
Ključne besede: ekstremofilni mikroorganizmi, mikrobna ekologija, ekstremofili, oligotrofi, psihrofili, halofili, termofili
Objavljeno v DiRROS: 05.08.2024; Ogledov: 50; Prenosov: 78
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2. Molecular screening for cyanobacteria and their cyanotoxin potential in diverse habitatsMaša Jablonska, Tina Eleršek, Polona Kogovšek, Sara Skok, Andreea Oarga-Mulec, Janez Mulec, 2024, izvirni znanstveni članek Povzetek: Cyanobacteria are adaptable and dominant organisms that exist in many harsh and extreme environments due to their great ecological tolerance. They produce various secondary metabolites, including cyanotoxins. While cyanobacteria are well studied in surface waters and some aerial habitats, numerous other habitats and niches remain underexplored. We collected 61 samples of: (i) biofilms from springs, (ii) aerial microbial mats from buildings and subaerial mats from caves, and (iii) water from borehole wells, caves, alkaline, saline, sulphidic, thermal, and iron springs, rivers, seas, and melted cave ice from five countries (Croatia, Georgia, Italy, Serbia, and Slovenia). We used (q)PCR to detect cyanobacteria (phycocyanin intergenic spacer—PC-IGS and cyanobacteria-specific 16S rRNA gene) and cyanotoxin genes (microcystins—mcyE, saxitoxins—sxtA, cylindrospermopsins—cyrJ), as well as amplicon sequencing and morphological observations for taxonomic identification. Cyanobacteria were detected in samples from caves, a saline spring, and an alkaline spring. While mcyE or sxtA genes were not observed in any sample, cyrJ results showed the presence of a potential cylindrospermopsin producer in a biofilm from a sulphidic spring in Slovenia. This study contributes to our understanding of cyanobacteria occurrence in diverse habitats, including rare and extreme ones, and provides relevant methodological considerations for future research in such environments.
Ključne besede: extreme environments, cylindrospermopsin, sulphidic springs, caves, qPCR, PC-IGS
Objavljeno v DiRROS: 05.08.2024; Ogledov: 40; Prenosov: 15
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3. Combined use of chlorophyll a and phycocyanin fluorescence sensors for quantification and differentiation of phytoplankton : a useful approach for small surface water bodiesTinkara Rozina, Tina Eleršek, Maja Zupančič Justin, Andrej Meglič, 2018, izvirni znanstveni članek Povzetek: Sensors based on in vivo measurements of photosynthetic pigments fluorescence enable real-time phytoplankton monitoring with high spatial and temporal resolution. A combination of chlorophyll a (CHL) and phycocyanin (PC) fluorescence sensors was used for phytoplankton quantification and differentiation in two small water bodies, Koseze Pond and pond in Hotinja vas. The high correlation of CHL and PC fluorescence signals with biovolume was confirmed during the two-year monitoring in anatural pond environment in spite of a seasonal succession of the phytoplankton. Additionally, disturbances of the sensors were investigated. Water bodies containing predominantly algae yielded false positive signals of the PC sensor, which reached up to 1% of the intensity of the CHL signal. Similarly, underestimated counts of cyanobacteria measured with CHL fluorescence sensor can be adjusted using PC fluorescence sensor.
Ključne besede: small water bodies, algae, cyanobacteria, fluorescence sensors, biovolume
Objavljeno v DiRROS: 01.08.2024; Ogledov: 80; Prenosov: 48
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4. "Only introduced" or "invasive" : spread of the alga Aulacoseira ambigua f. japonica from Asia to Africa and EuropeTina Eleršek, 2018, izvirni znanstveni članek Povzetek: Many non-native algal species are found in waters all over the world. Many terms are used to describe such organisms that have expanded their distribution. However, a unified model or concept remains to be defined, as how biological ‘invasions’ are seen depends on the perspective. Understanding invasive organisms is important for biodiversity, science policy and water management. During monitoring sampling at Slivniško Lake (Slovenia) in 2016, the curved diatom Aulacoseira ambigua f. japonica Tuji & D.M. Williams was identified. This species originates from Japan, from where it was described more than 100 years ago. The chronology of the published distributions of A. ambigua f. japonica defines its spread from Japan to Asia, then to western Russia and South Africa, and now to central Europe. This study provides further evidence that A. ambigua f. japonica has become established in Europe (Slovenia), as supported by light microscopy and scanning electron microscopy. To the best of our knowledge, this is the first qualitative and quantitative description of A. ambigua f. japonica in Europe. It has been suggested that the shape of these algal colonies is significant for the interpretation of ecological information, and indeed, also in the present case, spiral colonies were found in this eutrophic water body. Although curved cells and colonies can also be interpreted as (sub)populations or morphological variants, only detailed molecular studies can reveal if these also have taxonomic significance.
Ključne besede: algae, introduced species, invasive species, scanning electron microscopy
Objavljeno v DiRROS: 01.08.2024; Ogledov: 92; Prenosov: 107
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5. DNAqua-Net : developing new genetic tools for bioassessment and monitoring of aquatic ecosystems in EuropeFlorian Leese, Tina Eleršek, Cene Fišer, Ana Rotter, Bojana Žegura, Irena Maček, 2016, izvirni znanstveni članek Povzetek: The protection, preservation and restoration of aquatic ecosystems and their functions are of global importance. For European states it became legally binding mainly through the EU-Water Framework Directive (WFD). In order to assess the ecological status of a given water body, aquatic biodiversity data are obtained and compared to a reference water body. The quantified mismatch obtained determines the extent of potential management actions. The current approach to biodiversity assessment is based on morpho-taxonomy. This approach has many drawbacks such as being time consuming, limited in temporal and spatial resolution, and error-prone due to the varying individual taxonomic expertise of the analysts. Novel genomic tools can overcome many of the aforementioned problems and could complement or even replace traditional bioassessment. Yet, a plethora of approaches are independently developed in different institutions, thereby hampering any concerted routine application. The goal of this Action is to nucleate a group of researchers across disciplines with the task to identify gold-standard genomic tools and novel eco-genomic indices for routine application in biodiversity assessments of European fresh- and marine water bodies. Furthermore, DNAqua-Net will provide a platform for training of the next generation of European researchers preparing them for the new technologies. Jointly with water managers, politicians, and other stakeholders, the group will develop a conceptual framework for the standard application of eco-genomic tools as part of legally binding assessments.
Ključne besede: aquatic ecosystems, biodiversity, monitoring, genomic tools
Objavljeno v DiRROS: 25.07.2024; Ogledov: 123; Prenosov: 59
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6. A European multi lake survey dataset of environmental variables, phytoplankton pigments and cyanotoxinsEvanthia Mantzouki, Špela Remec-Rekar, Tina Eleršek, 2018, izvirni znanstveni članek Povzetek: Under ongoing climate change and increasing anthropogenic activity, which continuously challenge ecosystem resilience, an in-depth understanding of ecological processes is urgently needed. Lakes, as providers of numerous ecosystem services, face multiple stressors that threaten their functioning. Harmful cyanobacterial blooms are a persistent problem resulting from nutrient pollution and climate-change induced stressors, like poor transparency, increased water temperature and enhanced stratification. Consistency in data collection and analysis methods is necessary to achieve fully comparable datasets and for statistical validity, avoiding issues linked to disparate data sources. The European Multi Lake Survey (EMLS) in summer 2015 was an initiative among scientists from 27 countries to collect and analyse lake physical, chemical and biological variables in a fully standardized manner. This database includes in-situ lake variables along with nutrient, pigment and cyanotoxin data of 369 lakes in Europe, which were centrally analysed in dedicated laboratories. Publishing the EMLS methods and dataset might inspire similar initiatives to study across large geographic areas that will contribute to better understanding lake responses in a changing environment.
Ključne besede: biological pigments, cyanotoxins, ecology, hydrobiology, data, datasets
Objavljeno v DiRROS: 24.07.2024; Ogledov: 92; Prenosov: 173
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7. Ecotoxicity of disinfectant benzalkonium chloride and its mixture with antineoplastic drug 5-fluorouracil towards alga Pseudokirchneriella subcapitataTina Eleršek, Maja Ženko, Metka Filipič, 2018, izvirni znanstveni članek Povzetek: Background
Benzalkonium chloride (BAC) is one of the most common ingredients of the disinfectants. It is commonly detected in surface and wastewaters where it can interact with the residues of pharmaceuticals that are also common wastewater pollutants. Among the latter, the residues of antineoplastic drugs are of particular concern as recent studies showed that they can induce adverse effect in aquatic organisms at environmentally relevant concentrations.
Methods
Ecotoxicity of BAC as an individual compound and in a binary mixture with an antineoplastic drug 5-fluorouracil (5-FU) was determined towards alga Pseudokirchneriella subcapitata, a representative of primary producers. The toxicity of the BAC+5-FU binary mixture was predicted by the two basic models: concentration addition (CA) and independent action (IA), and compared to the experimentally determined toxicity. Additionally combination index (CI) was calculated to determine the type of interaction.
Results
After 72 h exposure to BAC a concentration dependent growth inhibition of P. subcapitata was observed with an EC50 0.255 mg/L. Comparing the predicted no effect concentration to the measured concentrations in the surface waters indicate that BAC at current applications and occurrence in aquatic environment may affect algal populations. The measured toxicity of the mixture was higher from the predicted and calculated CI confirmed synergistic effect on the inhibition of algal growth, at least at EC50 concentration. The observed synergism may have impact on the overall toxicity of wastewaters, whereas it is less likely for general environments because the concentrations of 5-FU are several orders of magnitude lower from its predicted no effect concentration.
Discussion
These results indicate that combined effects of mixtures of disinfectants and antineoplastic drugs should be considered in particular when dealing with environmental risk assessment as well as the management of municipal and hospital wastewaters.
Ključne besede: ecotoxicity, benzalkonium chloride, algae, 5-fluorouracil, synergistic inhibition
Objavljeno v DiRROS: 24.07.2024; Ogledov: 99; Prenosov: 281
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8. Temperature effects explain continental scale distribution of cyanobacterial toxinsEvanthia Mantzouki, Tina Eleršek, 2018, izvirni znanstveni članek Povzetek: nsight into how environmental change determines the production and distribution of cyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus on hepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g., anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to their potency. Most studies examine the relationship between individual toxin variants and environmental factors, such as nutrients, temperature and light. In summer 2015, we collected samples across Europe to investigate the effect of nutrient and temperature gradients on the variability of toxin production at a continental scale. Direct and indirect effects of temperature were the main drivers of the spatial distribution in the toxins produced by the cyanobacterial community, the toxin concentrations and toxin quota. Generalized linear models showed that a Toxin Diversity Index (TDI) increased with latitude, while it decreased with water stability. Increases in TDI were explained through a significant increase in toxin variants such as MC-YR, anatoxin and cylindrospermopsin, accompanied by a decreasing presence of MC-LR. While global warming continues, the direct and indirect effects of increased lake temperatures will drive changes in the distribution of cyanobacterial toxins in Europe, potentially promoting selection of a few highly toxic species or strains.
Ključne besede: microcystin, anatoxin, cylindrospermopsin, temperature, direct effects, indirect effects, spatial distribution, European Multi Lake Survey
Objavljeno v DiRROS: 24.07.2024; Ogledov: 105; Prenosov: 80
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9. Stratification strength and light climate explain variation in chlorophyll a at the continental scale in a European multilake survey in a heatwave summerDaphne Donis, Evanthia Mantzouki, Daniel F. McGinnis, Dominic Vachon, Irene Gallego, Hans-Peter Grossart, Lisette N. de Senerpont Domis, Sven Teurlincx, Laura Seelen, Miquel Lürling, Špela Remec-Rekar, Tina Eleršek, 2021, izvirni znanstveni članek Povzetek: To determine the drivers of phytoplankton biomass, we collected standardized morphometric, physical, and biological data in 230 lakes across the Mediterranean, Continental, and Boreal climatic zones of the European continent. Multilinear regression models tested on this snapshot of mostly eutrophic lakes (median total phos-phorus [TP]=0.06 and total nitrogen [TN]=0.7 mg L1), and its subsets (2 depth types and 3 climatic zones), show that light climate and stratification strength were the most significant explanatory variables for chloro-phylla(Chla) variance. TN was a significant predictor for phytoplankton biomass for shallow and continental lakes, while TP never appeared as an explanatory variable, suggesting that under high TP, light, which partially controls stratification strength, becomes limiting for phytoplankton development. Mediterranean lakes were the warmest yet most weakly stratified and had significantly less Chlathan Boreal lakes, where the temperature anomaly from the long-term average, during a summer heatwave was the highest (+4C) and showed a signifi-cant, exponential relationship with stratification strength. This European survey represents a summer snapshotof phytoplankton biomass and its drivers, and lends support that light and stratification metrics, which are bothaffected by climate change, are better predictors for phytoplankton biomass in nutrient-rich lakes than nutrient concentrations and surface temperature.
Objavljeno v DiRROS: 19.07.2024; Ogledov: 88; Prenosov: 94
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10. Lethal and sub-lethal effects and modulation of gene expression induced by T kinase inhibitors in zebrafish (Danio Rerio) embryosTina Eleršek, Matjaž Novak, Mateja Mlinar, Igor Virant, Nika Bahor, Karin Leben, Bojana Žegura, Metka Filipič, 2022, izvirni znanstveni članek Povzetek: Tyrosine kinase inhibitors (TKIs) are designed for targeted cancer therapy. The consumption of these drugs during the last 20 years has been constantly rising. In the zebrafish (Danio rerio) embryo toxicity test, we assessed the toxicity of six TKIs: imatinib mesylate, erlotinib, nilotinib, dasatinib, sorafenib and regorafenib. Imatinib mesylate and dasatinib induced lethal effects, while regorafenib, sorfenib and dasatinib caused a significant increase of sub-lethal effects, predominantly oedema, no blood circulation and formation of blood aggregates. The analyses of the changes in the expression of selected genes associated with the hormone system after the exposure to imatinib mesylate, dasatinib and regorafenib demonstrated that all three tested TKIs deregulated the expression of oestrogen receptor esr1, cytochrome P450 aromatase (cypa19b) and hydroxysteroid-dehydrogenase (hsd3b), regorafenib, and also thyroglobulin (tg). The expression of genes involved in the DNA damage response (gadd45 and mcm6) and apoptosis (bcl2) was deregulated only by exposure to regorafenib. The data indicate that common mechanisms, namely antiangiogenic activity and interference with steroidogenesis are involved in the TKI induced sub-lethal effects and potential hormone disrupting activity, respectively. The residues of TKIs may represent an environmental hazard; therefore, further ecotoxicological studies focusing also on the effects of their mixtures are warranted.
Ključne besede: aquatic toxicity, tyrosine kinase inhibitors, zebrafish embryo toxicity test, gene expression, environmental hazard
Objavljeno v DiRROS: 16.07.2024; Ogledov: 117; Prenosov: 88
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