Rebok, Katerina

Preferred name

Rebok, Katerina

Official Name

Rebok, Katerina

Main Affiliation

katerinarebok@yahoo.com

Now showing 1 - 10 of 14

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Characterization and identification of selected metal-binding biomolecules from hepatic and gill cytosols of Vardar chub (Squalius vardarensis Karaman, 1928) using various techniques of liquid chromatography and mass spectrometry
(Oxford University Press (OUP), 2019-06-19)
Krasnići, Nesrete
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Dragun, Zrinka
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Kazazić, SnjeŽana
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Muharemović, Hasan
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Erk, Marijana
Metals play crucial physiological roles, but they can also cause irreparable toxic effects through binding to important cellular biomolecules in aquatic organisms. The aim of this study was to determine the exact molecular masses and to identify several selected metal-binding biomolecules in hepatic and gill cytosols of Vardar chub (Squalius vardarensis Karaman, 1928). Methods applied for the achievement of this goal were SEC-AEC-HPLC for two-dimensional separation of cytosolic biomolecules, HR ICP-MS for metal measurements, and mass spectrometry (MALDI-TOF-MS and LC-MS/MS) for biomolecule mass determination and identification. The analyzed biomolecules included: Fe-binding biomolecules, which were identified as hemoglobin subunit β in the liver (molecular masses of ∼15 kDa), and hemoglobin subunits α and β in the gills (molecular masses of ∼11 kDa, ∼13 kDa and ∼15 kDa); heat-stable Cd-binding biomolecules, which were identified as MT isoforms MT-I and MT-II (molecular mass of ∼6.0 kDa in both liver and gills, and an additional 4.9 kDa isoform in the gills); and heat-stable Mo-binding biomolecules of molecular masses equal to 3.3 kDa (in the gills) and 8.5 kDa (in the liver). An important finding of this study was the obvious presence of different isoforms of the same biomolecules in the liver and gills. This was, among others, manifested through the absence of Zn binding to MTs only in the gills, indicating that the same type of biomolecule can be responsible for different functions in different organs. Thus, for better understanding of metal behaviour in aquatic organisms, it is crucial to identify cellular metal-binding biomolecules and their functions.
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Pollution impact on metal and biomarker responses in intestinal cytosol of freshwater fish
(Springer Science and Business Media LLC, 2023-05)
Filipović Marijić, Vlatka
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Krasnići, Nesrete
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Valić, Damir
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Kapetanović, Damir
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Vardić Smrzlić, Irena
In the present study, essential and nonessential metal content and biomarker responses were investigated in the intestine of fish collected from the areas polluted by mining. Our objective was to determine metal and biomarker levels in tissue responsible for dietary intake, which is rarely studied in water pollution research. The study was conducted in the Bregalnica River, reference location, and in the Zletovska and Kriva Rivers (the Republic of North Macedonia), which are directly influenced by the active mines Zletovo and Toranica, respectively. Biological responses were analyzed in Vardar chub (Squalius vardarensis; Karaman, 1928), using for the first time intestinal cytosol as a potentially toxic cell fraction, since metal sensitivity is mostly associated with cytosol. Cytosolic metal levels were higher in fish under the influence of mining (Tl, Li, Cs, Mo, Sr, Cd, Rb, and Cu in the Zletovska River and Cr, Pb, and Se in the Kriva River compared to the Bregalnica River in both seasons). The same trend was evident for total proteins, biomarkers of general stress, and metallothioneins, biomarkers of metal exposure, indicating cellular disturbances in the intestine, the primary site of dietary metal uptake. The association of cytosolic Cu and Cd at all locations pointed to similar pathways and homeostasis of these metallothionein-binding metals. Comparison with other indicator tissues showed that metal concentrations were higher in the intestine of fish from mining-affected areas than in the liver and gills. In general, these results indicated the importance of dietary metal pathways, and cytosolic metal fraction in assessing pollution impacts in freshwater ecosystems.
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Effects of water contamination with heavy metals on pigmented macrophages in spleen of Vardar chub (Squalius vardarensis Karaman) from three rivers in the North-Eastern region of North Macedonia
(Hrvatski Prirodoslovno Drustvo (Croatian Society for Natural Sciences), 2022-07-01)
Ivanova, Lozenka
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Dragun, Zrinka
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Kostov, Vasil
Background and purpose: Pigmented macrophage aggregates (PMAs) are a part of the immune system of fish and are considered as valuable biomarkers of the impact of water pollution on fish health.Materials and methods: Immunomodulatory effect of water contaminated with high levels of metals on spleen and splenic PMAs of Vardar chub (Squalius vardarensis) (n=129) was examined in two seasons, spring, and autumn 2012. For this purpose, three rivers were chosen: the Zletovska River, heavily contaminated with metals, the Kriva River, moderately contaminated with metals combined with high level of organic matter, and the Bregalnica River, without heavy metal contamination. Spleen masses and splenosomatic indices (SSI) were used for determining the general impact of water contamination on the immune system of Vardar chub. Moreover, volumes and numbers of PMAs within spleen tissue were determined stereologically.Results: The isolated effect of high exposure to metals caused the reduction of spleen mass and/or SSI in the fish from the Zletovska River. The combined effect of exposure to metals and high levels of nutrients in the fish from the Kriva River referred to stimulation of PMAs response, namely increased volumes of splenic PMAs. The existence of seasonally dependent differences was noted since the observed variability in PMAs between rivers occurred only in the autumn.Conclusions: Splenic PMAs in the Vardar chub can be used as an additional biomarker of metal pollution, but with caution, since enhancement of the volumes and numbers of MACs depends on the exposure level of heavy metals, on the presence of the other contaminants, as well as on the physiological condition of the fish.</jats:p>
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The effect of different pollutants exposure on the pigment content of pigmented macrophage aggregates in the spleen of Vardar chub (Squalius vardarensis Karaman, 1928)
(Wiley, 2020-09)
Ivanova, Lozenka
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Dragun, Zrinka
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Kostov, Vasil
Pigmented macrophage aggregates (MAs) are known to change under influence of various factors, such as aging, season, starvation, and/or pollution. In this study, changes in the pigment content of the MAs in the spleen of Vardar chub (Squalius vardarensis, Karaman) (n = 129) collected in spring and autumn, from three rivers with different pollution impact was examined: Zletovska River (metals), Kriva River (metals and municipal wastewater), and Bregalnica River (municipal wastewater). Collected data revealed increased relative volume and number of MAs containing hemosiderin under the influence of metals, significant in autumn (p < .05). In chub exposed to metals combined with municipal wastewater, significant increase of lipochrome accumulation in MAs in autumn, melanin in MAs in fish captured in the spring season, and number of splenic MAs containing combination of melanin and lipochrome was noted. Volumes and number of MAs containing combination of hemosiderin and lipochrome increased in spleen of fish captured in autumn from both Zletovska River and Kriva River, most likely due to the contribution of hemosiderin and lipochrome, respectively. Values measured for the various pigments in splenic MAs in fish captured from Bregalnica River, were overall closer to the values measured for fish captured from Kriva River. Notably, melanin and lipochrome are more likely to be found in fish from waters influenced by municipal wastewater (organic pollution) and hemosiderin in fish spleen from water influenced by mining activity (heavy metals pollution).
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Seasonal fish diversity, distribution, and their relation to physicochemical parameters: A case study of the Lepenc River Basin, Kosovo
(Wydawnictwo Naukowe Gabriel Borowski (WNGB), 2025-04-02)
Grapci-Kotori, Linda
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Xërxa, Bardh
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Ibrahimi, Halil
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Bilalli, Astrit
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Geci, Donard
This study presents the findings from three seasonal field surveys conducted in the Lepenc River and its tributaries during 2023. The surveys were carried out on May, July, and October, focusing on six sampling sites: Prevallë, Lepenc (Kaçanik), Hani i Elezit, Jezerc, Gerlicë, and Nerodime (Kaçanik). Standardized electrofishing technique was applied, in accordance with the methods used by the European Union Water Framework Directive (EU WFD) monitoring protocols, which have been implemented in many Balkan regions. A total of 790 fish specimens were caught, identified, measured, and subsequently released back into their natural habitats. The species found during this investigation were: Salmo sp., Barbus balcanicus, Squalius varedaresnisi, Alburnoides thessalicus, Alburnus thessalicus, Gobio balcanicus, Phoxinus sp., and Oxynoemacheilus bureschi. The sampling site in Gerlicë consistently showed no presence of fish, likely due to pollution. The findings provide a comprehensive overview of fish community composition and their seasonal variations, highlighting the influence of physicochemical parameters on aquatic biodiversity. The results emphasize the urgent need for conservation measures to address habitat degradation and pollution, ensuring the preservation and restoration of biodiversity in the Lepenc River Basin.
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Malondialdehyde concentrations in the intestine and gills of Vardar chub (Squalius vardarensis Karaman) as indicator of lipid peroxidation
(Springer Science and Business Media LLC, 2017-07)
Dragun, Zrinka
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Filipović Marijić, Vlatka
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Krasnići, Nesrete
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Ramani, Sheriban
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Valić, Damir
A lipid peroxidation product, malondialdehyde (MDA), was studied in Vardar chub (Squalius vardarensis Karaman) as an indicator of oxidative stress, using native fish from three rivers in northern Macedonia: the mining-impacted Zletovska and Kriva rivers and the agriculturally impacted Bregalnica River. MDA concentrations were measured in the intestine in the spring and autumn of 2012 and in the gills in autumn. The aims of the study were to establish the type of contamination which provokes a more pronounced MDA increase, as well as the organ which more reliably reflects the occurrence of oxidative stress. MDA levels in the intestine in spring amounted to 3.29-155.8 nmol g-1 and in autumn to 4.85-111.1 nmol g-1, whereas MDA concentrations in the gills in autumn were 7.69-147.5 nmol g-1. Stronger influence of organic contamination on development of oxidative stress was observed in both organs, as seen from higher median MDA concentrations in autumn in fish from the highly pesticide-contaminated Bregalnica River (gills 78.4 nmol g-1; intestine 23.5 nmol g-1) compared to the highly metal-contaminated Zletovska River (gills 15.9 nmol g-1; intestine 17.4 nmol g-1). The response of the gills to contamination was twice stronger than that of the intestine. The majority of fish from the pesticide-polluted river had increased MDA in the gills, in contrast to only sporadically increased MDA in the intestine. Our results indicated that development of oxidative stress strongly depends on the selected fish organ and that the gills seem to be a better choice for monitoring oxidative stress than the intestine, due to their continuous and direct exposure to polluted river water.
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Mining waste as a cause of increased bioaccumulation of highly toxic metals in liver and gills of Vardar chub (Squalius vardarensis Karaman, 1928)
(Elsevier BV, 2019-04)
Dragun, Zrinka
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Tepić, Nataša
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Ramani, Sheriban
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Krasnići, Nesrete
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Filipović Marijić, Vlatka
Freshwater contamination with mining waste can result with high concentrations of toxic metals in the water and in fish organs. In North-Eastern Macedonia, several rivers (e.g., Zletovska, Kriva) are exposed to acid mine drainage from active Pb/Zn mines. Previous studies confirmed high concentrations of dissolved metals in their water. This study was performed in liver and gills of Vardar chub (Squalius vardarensis Karaman, 1928) from three Macedonian rivers (Bregalnica, Kriva and Zletovska) in spring and autumn 2012. The aim was to establish if increased exposure to certain metals have resulted with their increased bioaccumulation. The concentrations of 19 elements were measured in cytosolic tissue fractions, to obtain information on metabolically available metal species. The following ranges of cytosolic concentrations of highly toxic elements were measured in the Vardar chub liver (in μg/L): Cd, 1.18-184; Cs, 0.25-25.4; Tl, 0.02-5.80; Pb, 0.70-61.1. Their ranges measured in the gills (in μg/L) were the following: Cd, 0.24-59.2; Cs, 0.39-24.4; Tl, 0.01-1.00; Pb, 0.65-87.2. Although the water of the mining impacted Zletovska River was highly contaminated with several essential metals, especially with Mn and Zn, the majority of essential elements (Na, K, Ca, Mg, Co, Cu, Fe, Mn, Mo, and Zn) did not reflect the exposure level. In contrast, seven nonessential elements reflected the level of exposure in the water. Significantly increased hepatic and gill concentrations of Cs, Rb, Sr, and Tl were detected in Vardar chub from the Zletovska River compared to the other two rivers, of Cd and Pb in the Zletovska and Kriva River compared to Bregalnica, and of V in the Bregalnica River compared to Zletovska and Kriva rivers. Observed significant metal bioaccumulation, in particular of highly toxic elements, as a consequence of exposure to water contaminated with mining waste points to necessity of intensified supervision of mining impacted rivers.
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Effects of heavy metal pollution on pigmented macrophages in kidney of Vardar chub (Squalius vardarensis Karaman)
(Wiley, 2017-08)
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Dragun, Zrinka
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Ramani, Sheriban
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Ivanova, Lozenka
Pollution with heavy metals may influence the immune system of fish, leading to impairment of their health or even increase their mortality. The fish kidney is one of the first fish organs to be affected by water contamination. Amounts of kidney macrophages (MACs), which are involved in fish immune response, as well as the qualitative and quantitative changes in the pigmented MACs in fish kidney, are used as biomarkers of pollution. Therefore, in this study, we have evaluated relative and total volumes of trunk kidney pigmented MACs, and analyzed the pigments accumulated within them. Fish were sampled from two mining impacted rivers, Kriva and Zletovska, highly contaminated with heavy metals, and from one reference river, Bregalnica, in spring and autumn of 2012. We have observed that main pigments found in kidney MACs of Vardar chub were melanin and lipofuscin/ceroid, as well as that relative volumes of MACs ranged from 0.56 to 1.68%. Moreover, the results showed that relative volumes of pigmented MACs were higher in metal contaminated rivers, especially in autumn season in the Zletovska River, concurrently with extremely high metal exposure. In addition, condition factors and kidney somatic indices were found significantly lower in the Zletovska River in both seasons, autumn and spring, possibly also as a consequence of high water pollution. Our data confirm that increase in relative volumes of pigmented MACs may serve as warning sign of potential heavy metal pollution in aquatic environment.
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Impact of Industrial Pollution and GenotoxicEffects in Marsh Frog (<i>Pelophylax ridibundus</i>(Pallas, 1771)) Populations in Kosovo
(HARD Publishing Company, 2025-09-26)
Hyseni, Alban
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Bilalli, Astrit
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Grapci-Kotori, Linda
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Kastrati, Blearta
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Berisha, Alban
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Evaluation of histopathological alterations in the gills of Vardar chub ( Squalius vardarensis Karaman) as an indicator of river pollution
(Elsevier BV, 2015-08)
Barišić, Josip
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Dragun, Zrinka
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Ramani, Sheriban
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Filipović Marijić, Vlatka
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Krasnići, Nesrete
Quanti!cation of histopathological alterations in the gills of Vardar chub (Squalius vardarensis Karaman) was performed in 2012 in rivers of north-eastern Macedonia, with the aim to examine the effects of water quality in the rivers (Zletovska and Kriva River-impacted by active Pb/Zn mines; Bregalnica River- contaminated by agricultural waste). The biological alterations in chub were classi!ed as: circulatory disturbances, regressive and progressive changes, but their severity differed. Altogether the mildest changes were observed in the gills of chub from the Bregalnica River, a less polluted river, whereas mining impacted rivers were characterized by more severe alterations. In the gills of chub from the Zletovska River, which is highly contaminated with numerous metals, sulphates and chlorides, the highest lesion indices were found for the regressive changes of both epithelium and supporting tissue, with typical lesions referring to atrophy, thinning and lifting of epithelial cells, necrosis of epithelium and chloride cells, as well as deformations of lamellar cartilaginous base. Gill damages of chub from the Kriva River were overall milder compared to the Zletovska River, in accordance with pollution status. In the gills of chub from that river, progressive changes were more pronounced, speci!cally severe hyperplasia of mucous cells and epithelium in the interlammellar space, leading to fusion of lamellae, as well as hypertrophy of chloride cells. The comparison between seasons indicated higher intensity of progressive changes in all three rivers in autumn, when water level was very low, and consequently, water con- tamination was more pronounced due to concentration effect. The pattern and severity of histopatho- logical alterations in the chub gills re"ected differences in contamination levels and type of contaminants in different rivers and sampling periods, and thus have been proven as a valuable indicator of water quality

Rebok, Katerina

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