281. Preliminary experiments into colonization of microorganisms from activated sludge on different types of plasticsTjaša Matjašič, Tanja Dreo, Zoran Samardžija, Oliver Bajt, Tjaša Kanduč, Tatjana Simčič, Nataša Mori, 2020, original scientific article Abstract: The presence of plastics in the environment is currently one of the most pressing global environmental problems. Microorganisms start to form biofilms on plastic surfaces when they first come in contact with the biosphere; however, these interactions and processes are little understood, especially in freshwaters. This study aimed to better understand the colonization process of microorganisms from activated sludge on plastic materials exhibiting different surface characteristics. We inoculated synthetic fabric (PET), water bottles (PET), and plastic bags for packing vegetables and fruits (HDPE) with microorganisms from activated sludge. Mixtures of plastics and activated sludge, as well as the control, were incubated at 22-24°C in Bushnell Haas (BH) liquid medium and shaken at 120 rpm for two months. The mixtures were sub-sampled weekly and seeded into fresh BH medium with test plastic materials to avoid feeding microorganisms on dead biomass. The colonization was followed by measuring optical density (OD600) of liquid medium, by measurements of isotopic composition of carbon (δ13C) in untreated and treated plastic materials and, with in-specting the plastics surface with scanning electron microscopy (SEM). Overall, the study confirmed differences between colonizing microorganisms on different plastic material when comparing SEM micrographs of materials from the flasks inoculated with activated sludge. The texture of the HDPE bag changed during the experiment in both, control and inoculated flasks, but it is not clear whether the observed changes were due to abiotic or biotic factors. We concluded that microorganisms from activated sludge are capable of colonizing both PET and HDPE materials, and biofilm formation is most probably influenced by the chemical composition of plastics and their surface characteristics.
Keywords: biofilm, plastics, SEM, isotopic composition of carbon, co-cultivation, UV sterilization Published in DiRROS: 31.07.2024; Views: 171; Downloads: 144
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282. Setting sail for Paris 2024 : retrospective analysis ofworld-class ILCA 7 olympic sailors’ cardiorespiratory fitness (2015–2020)Damir Zubac, Zoran Valić, Vladimir Ivančev, 2024, other scientific articles Abstract: The aim of this retrospective analysis was to provide a more comprehensive understanding of the cardiorespiratory profile of world-class ILCA-7 sailors (n = 3, all males), through a longitudinal evaluation offering real-world data on physiological profile and exercise intensity domains. The cardiopulmonary exercise testing (CPET) was performed by the same researchers using the same equipment during the study. Assessments took place twice a year, aligning with major international competition preparations. Participants trained and competed at the same sailing club in Split, Croatia, under consistent supervision from the same team throughout the study, winning a total of 21 medals at major international competitions. The recorded
ranged from 51.7 ± 1.6 to 61.9 ± 3.0 mL min−1 kg−1, respectively. Similarly, peak power output varied from 352 ± 10 to 426 ± 34 W. The changes in physiological responses at the ventilatory thresholds were proportional to the changes in peak cardiorespiratory fitness capacity. Interestingly, the oxygen pulse measured in 2015 was 25 ± 1 mL O2 beat−1. Over the subsequent 6 years, the O2 pulse marginally increased and appeared to stabilize at 27 ± 1 mL O2 beat−1 in 2020, when these athletes were 32 ± 3 years old. This work offers a broader understanding of world-class Olympic sailors’ cardiorespiratory fitness, going beyond the standard assessment of peak
to incorporate an analysis of ventilatory thresholds. While a direct link between cardiorespiratory fitness and competitive success remains ambiguous, the importance of a well-rounded aerobic capacity for excellence in ILCA-7 sailing class is evident. Keywords: olypmipcs, oxygen uptake, sailing Published in DiRROS: 31.07.2024; Views: 182; Downloads: 245
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284. The occurrence of the jellyfish Aequorea cf. forskalea in the Adriatic Sea : comparison of historical and recent dataAlenka Malej, Davor Lučić, Natalia Bojanić, Martin Vodopivec, Paolo Paliaga, Branka Pestorić, Ivana Violić, Nastjenjka Supić, 2022, original scientific article Abstract: Jellyfish are becoming an increasingly important component of studies of the global marine environment, as their frequent mass phenomena affect ecosystem performance and have economic and health consequences. Recent research has focused primarily on mass occurrences of scyphozoans and ctenophores, while less attention has been paid to hydromedusae blooms, which can also have significant impacts on the marine ecosystem with economic consequences. Like many members of the Scyphozoa and Ctenophora, Aequorea species can be numerous and form blooms. Based on surveys from 2000 to 2020 and information provided by marine professionals, we examine the (multiannual) variability, seasonality, and spatial distribution patterns of the poorly studied temperate species Aequorea cf. forskalea (Hydrozoa: Leptothecata). We hypothesized that this macrogelatinous jellyfish with a bipartite life cycle (benthic polyps and planktonic medusae) is sensitive to seasonal and long-term temperature fluctuations, particularly because temperature has been shown to play a critical role in mediating transitions in the life cycle of cnidarians. The cold-water affinity of A. cf. forskalea was confirmed by a significant negative correlation with temperature and the most frequent occurrence during the winter-spring period. For the northern Adriatic (Gulf of Trieste), sea temperature data and semi-quantitative plankton data are available for the first decade of the 20th century, allowing comparison of the historical data (1900-1911) with our current data set. Compared to historical records, the current occurrence of A. cf. forskalea differs significantly. With the warming of the northern Adriatic Sea since the beginning of the 20th century, the current phenology of A. cf. forskalea has changed, probably related to the delayed production of medusae by hydroids in autumn, the absence of medusae in this season and their less frequent occurrence in winter. Keywords: hydromedusae, blooms, long-term monitoring, multiannual variability, Mediterranean Sea Published in DiRROS: 31.07.2024; Views: 330; Downloads: 122
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285. First records of two Cuthona species (Gastropoda: Nudibranchia) in the Adriatic seaLovrenc Lipej, Borut Mavrič, Domen Trkov, 2015, original scientific article Abstract: Authors are reporting on the first records of two nudibranch species of the genus Cuthona in the Slovenian part of the Adriatic Sea. In the period from September 2014 to March 2015, specimens of Cuthona genovae and C. miniostriata were found at different localities in the mediolittoral and upper infralittoral belts. The findings of both Cuthona species represent the first records in the Adriatic Sea. Published in DiRROS: 29.07.2024; Views: 164; Downloads: 77
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286. Extraction of DNA from different sample types - a practical approach for GMO testingJana Žel, Tina Demšar, Dejan Štebih, Mojca Milavec, Kristina Gruden, 2015, original scientific article Abstract: Current methods based on DNA targets for the detection, identification and quantification of genetically modified organisms (GMOs) involve extraction of the DNA. Different extraction procedures have been developed for the great variety of samples from food, feed, seeds and particular plant parts. This makes the operation of routine analytical laboratories complex and workloads heavy. Here we present a decision-making system, developed over many years of GMO testing on different samples, that result in the application of only a few extraction methods for the majority of samples. Developed decision-making system enables quicker and more cost effective testing of GMOs. In addition, the performance of DNA extraction resulting from the use of the selected extraction methods is presented for use in subsequent testing of GMOs by real time PCR methods. This approach can be used as a model for similar systems based on nucleic acid analysis in food, feed, seeds and plants. Keywords: extraction methods, genetically modified organisms, GMO, decision- making system (biology), GMO testing, cetyltrimethylammonium bromide, CTAB Published in DiRROS: 29.07.2024; Views: 143; Downloads: 112
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287. Patterns in invertebrate drift from an alpine karst aquifer over a one year periodMaja Opalički, 2015, original scientific article Abstract: Patterns in invertebrate drift in the alpine karst Lipnik spring (Julian Alps, Slovenia) were investigated over a one year period. Monthly samplings of one permanent and two temporary springs, and one sampling of a spring brook benthos, yielded 23 Copepoda and Ostracoda species. More species (12) were found in the permanent than in the temporary springs (8 and 7), Elaphoidella phreatica (Sars, 1862) being the most frequent in all of them. No correlation was observed between precipitation and drift densities or the numbers of species in the permanent spring. In the temporary springs there were correlations between precipitation and the Shannon diversity index, equitability and changes in community composition. Conductivity of the water was the only physical parameter in the springs that correlated with precipitation. Species accumulation curves reached the asymptotes in all the springs but not for benthos. Keywords: alpine karst aquifer, groundwater, drift Published in DiRROS: 29.07.2024; Views: 167; Downloads: 100
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288. Additional record of the non-indigenous copepod Pseudodiaptomus marinus (Sato, 1913) in the Adriatic SeaDavor Lučić, Patricija Mozetič, Janja Francé, Petra Lučić, Lovrenc Lipej, 2015, original scientific article Abstract: The Indo-Pacific egg-carrying copepod Pseudodiaptomus marinus Sato, 1913 was recorded for the first time in the Port of Koper, Slovenia (Gulf of Trieste) in February 2015. This is the fourth finding of this species in the Mediterranean Sea, and the third for the Adriatic Sea. A rather high abundance of 73 ind. m-3 was recorded, which is considerably higher than previous findings in the Adriatic. Maritime transport is presumed to be the main cause of its introduction, primarily through ballast water release. Repeat sampling in May confirmed the presence of this copepod, indicating the possibility that the species has established a stable population in the Port of Koper. Keywords: copepods, Adriatic Sea, mesozooplankton, ballast waters Published in DiRROS: 29.07.2024; Views: 155; Downloads: 60
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289. Improvement of root architecture under abiotic stress through control of auxin homeostasis in Arabidopsis and Brassica cropsBranka Salopek-Sondi, Stephan Pollmann, Kristina Gruden, Ralf Oelmüller, Jutta Ludwig-Müller, 2015, original scientific article Abstract: Auxin plays an important role in many aspects of plant development including stress responses. Here we briefly summarize how auxin is involved in salt stress, drought (i.e. mostly osmotic stress), waterlogging and nutrient deficiency in Brassica plants. In addition, some mechanisms to control auxin levels and signaling in relation to root formation (under stress) will be reviewed. Molecular studies are mainly described for the model plant Arabidopsis thaliana, but we also like to demonstrate how this knowledge can be transferred to agriculturally important Brassica species, such as Brassica rapa, Brassica napus and Brassica campestris. Moreover, beneficial fungi could play a role in the adaptation response of Brassica roots to abiotic stresses. Therefore, the possible influence of Piriformospora indica will also be covered since the growth promoting response of plants colonized by P. indica is also linked to plant hormones, among them auxin. Keywords: auxin, root development, abiotic stress Published in DiRROS: 29.07.2024; Views: 168; Downloads: 73
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290. Transcriptome study and identification of potential marker genes related to the stable expression of recombinant proteins in CHO clonesAndrej Blejec, Marjanca Blas, Petra Nikolić, Dominik Gaser, Kristina Gruden, Aleš Belič, Špela Baebler, Uroš Jamnikar, Andrej Francky, Holger Laux, 2015, original scientific article Abstract: Background
Chinese hamster ovary (CHO) cells have become the host of choice for the production of recombinant proteins, due to their capacity for correct protein folding, assembly, and posttranslational modifications. The most widely used system for recombinant proteins is the gene amplification procedure that uses the CHO-Dhfr expression system. However, CHO cells are known to have a very unstable karyotype. This is due to chromosome rearrangements that can arise from translocations and homologous recombination, especially when cells with the CHO-Dhfr expression system are treated with methotrexate hydrate. The present method used in the industry for testing clones for their long-term stability of recombinant protein production is empirical, and it involves their cultivation over extended periods of time prior to the selection of the most suitable clone for further bioprocess development. The aim of the present study was the identification of marker genes that can predict stable expression of recombinant genes in particular clones early in the development stage.
Results
The transcriptome profiles of CHO clones with stable and unstable recombinant protein production were investigated over 10-weeks of cultivation, using a DNA microarray. We identified 14 genes that were differentially expressed between the stable and unstable clones already at 2 weeks from the beginning of the cultivation. Their expression was validated by reverse-transcription quantitative real-time PCR (RT-qPCR). Furthermore, the k-nearest neighbour algorithm approach shows that the combination of the gene expression patterns of only five of these 14 genes is sufficient to predict stable recombinant protein production in clones in the early phases of cell-line development.
Conclusions
The exact molecular mechanisms that cause unstable recombinant protein production are not fully understood. However, the expression profiles of some genes in clones with stable and unstable recombinant protein production allow prediction of such instability early in the cell-line development stage. We have thus developed a proof-of-concept for a novel approach to eliminate unstable clones in the CHO-Dhfr expression system, which saves time and labour-intensive work in cell-line development. Keywords: CHO cell line, stable recombinant protein production, gene expression, RT-qPCR, DNA microarray, mMarker genes Published in DiRROS: 29.07.2024; Views: 169; Downloads: 257
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