Browsing by Author "Oguz, Ahmet R."

Now showing 1 - 15 of 15

Determination of Cytotoxic, Genotoxic, and Oxidative Damage From Deltamethrin on Primary Hepatocyte Culture of Lake Van Fish,alburnus Tarichi
(Taylor & Francis Ltd, 2020) Kiraccakali, Ayse N.; Oguz, Ahmet R.
Deltamethrin is a widely used pyrethroits worldwide. Although the chemical is used to combat insects, it has effects on other non-target organisms. Deltamethrin is extensively used in agriculture, animal husbandry, and domestic areas in the Lake Van basin. The aim of this study was to determine the cytotoxic, genotoxic, and oxidative damage from deltamethrin on the primary hepatocyte culture of Lake Van fish (Alburnus tarichi). In this study, the toxic effects of different concentrations (0.01, 0.1, 1, and 10 mu M) of deltamethrin in the primary hepatocyte culture of Lake Van fish were investigated via liver enzymes aspartase aminotransferase (AST) and alanine aminotransferase (ALT), and the total antioxidant status (TAS), total oxidant status (TOS), lipid peroxidation (MDA), and DNA damage (8-OHdG). Deltamethrin caused an increase in the AST and ALT levels dependent on the dosage and time. The TAS and TOS levels increased at the end of 24 h and there was no difference at the end of 48 h. Deltamethrin did not affect the MDA level, but increased the 8-OHdG (P < 0.05). In conclusion, it can be said that high doses of deltamethrin (1 and 10 mu M) have a toxic effect on the primary hepatocyte culture of Lake Van fish.
Determination of Selected Endocrine Disrupting Chemicals in Lake Van, Turkey
(Springer, 2013) Oguz, Ahmet R.; Kankaya, Ertugrul
In the present study, we investigated the distribution of 17 beta-estradiol (E2), 17 alpha-ethynylestradiol (EE2), alkylphenol ethoxylates (APEs) and organochlorine pesticides (DDE/DDT) in water and sediment samples in the Eastern Anatolia of Turkey, Lake Van, which is the largest soda lake in the world. The procedure consisted of solid phase extraction performed with OASIS HLB cartridges followed by non-competitive enzyme-linked immunosorbent assays (ELISA). The endocrine disrupting compounds E2, EE2, and DDT/DDE were detected in most of the lake samples with mean concentrations of 0.996 +/- A 0.304, 0.050 +/- A 0.022, and 0.749 +/- A 0.658 ng/L in water, respectively. Mean concentrations of E2, EE2 and DDT/DDE in sediment were 0.098 +/- A 0.053, 0.091 +/- A 0.072, and 1.281 +/- A 0.754 ng/g, respectively. APEs were not measured in the sediment samples. The EDCs levels in surface water and sediment samples were lower than that of other countries. The EDCs were also found in effluent and influent municipal sewage samples. Van city municipal wastewater treatment plant has no removal efficiency for EDCs.
Development of Osmoregulatory Tissues in the Lake Van Fish (Alburnus Tarichi) During Larval Development
(Springer, 2018) Oguz, Ahmet R.
Lake Van is one of the largest alkaline lakes worldwide and Lake Van Fish (Alburnus tarichi Guldenstadt, 1814) is the only vertebrate species inhabiting it. Lake Van Fish is an anadromous species that migrates to the streams (salinity 0.02%, pH 8.42) flowing into Lake Van (salinity 0.22%, pH 9.8) during the spawning period (April-July). Following spawning, fish return to Lake Van while larvae remain in fresh water. This study examined the development of osmoregulatory organs and the distribution of ionocytes in Lake Van Fish larvae adapting to the highly alkaline water characterizing the lake. Ionocytes were marked immunohistochemically and observed in whole mounts with immunofluorescence staining using the Na+/K+ ATPase antibody. Ionocytes were first identified in the yolk sac membrane and skin, and then in the gills, digestive tract, and kidneys of larvae. The number of ionocytes on yolk sac membrane and skin decreased during larval development, indicating ionocytes on these tissues have a role in larvae osmoregulation. Larvae hatched from eggs in stream waters die when transferred to Lake Van water but survived in lake water diluted with deionized water. Thus, larvae need to go through certain alterations at the cellular and organ levels in order to adapt to the conditions of Lake Van water, indicating they do not enter this lake immediately after hatching.
Effects of 4-Chlorophenoxy Acetic Acid on Oxidative Stress and Antioxidant Enzymes in Primary Hepatocyte Cell Culture in Lake Van Fish (Alburnus Tarichi Guldenstadt 1814)
(Parlar Scientific Publications (p S P), 2020) Ozok, Necati; Oguz, Ahmet R.
Synthetic plant regulators are used extensively and uncontrollably in order to increase agricultural production. The 4-chlorophenoxyacetic acid used for this purpose is contaminating soil and water, and leaving residue on the products. Therefore, it cannot be ruled out that there may be adverse effects on nontarget organisms and especially on animal health. In this study, the effects of oxidative stress and antioxidant enzymes were investigated in the primary hepatocyte culture of Lake Van fish (Alburnus tarichi, Guldenstadt 1814) exposed to 4-chlorophenoxyacetic acid. Statistically significant reductions in superoxide dismutase, catalase, glutathione peroxidase, and glutathione-S-transferase enzyme activities and reduced glutathione levels were observed in comparison with the obtained findings in the control group (P <= 0.05). There was also a significant increase in the level of malondialdehyde, a product of lipid peroxidation (P <= 0.05). As a result, it was determined that Lake Van fish treated with different concentrations of 4-chlorophenoxyacetic acid exhibited oxidative stress and lipid peroxidation in the primary hepatocyte cell culture.
Effects of Salinity on Gill Histology in Sailfin Velifera (Poecilia Velifera)
(Springer, 2024) Oguz, Ahmet R.; Sepil, Ahmet; Alkan, Zehra; Azizoglu, Burcu Ergoz; Sen, Fazil; Oguz, Elif Kaval
Fish live in aquatic areas with varying salinity from fresh water to seawater. Gills are one of the most important osmoregulatory organs for maintaining the salt-water balance. In this study, changes in the gills of velifera (Poecilia sphenops) acclimated to 20, 30, 40, and 50 ppt of saline in the laboratory were examined histologically and immunohistochemically. Mucus cells (MCs), proliferating cell nuclear antigen (PCNA), mitochondria-rich cells (MRCs), and heat shock proteins (HSP70) + cells were marked in the gill tissue, which underwent routine histological procedures, and the severity of histological alterations increase with the increase of the salinity. When the gills were examined histologically, it was determined that there was an increase in cells due to hyperplasia, especially in the primary lamellae. A rapid increase in MC and HSP70 + cell numbers was observed in the 20 and 30 ppt groups. Although PCNA + cells were present in each salinity group, they were observed in the salinity group up to 50 ppt. An increase in the number and volume of MRCs was observed with increasing salinity. Based on the histological and immunohistochemical results, it is thought that the cytological and molecular arrangements of cells in gills of sailfin velifera under different levels of salinity are essential for the regulation of ion and salt balance.
Environmental Regulation of Mitochondria-Rich Cells in Chalcalburnus Tarichi (Pallas, 1811) During Reproductive Migration
(Springer, 2013) Oguz, Ahmet R.
Chalcalburnus tarichi is an anadromous cyprinid fish that has adapted to extreme conditions (salinity 22 aEuro degrees, pH 9.8 and alkalinity 153 mEq x l(-1)) in Lake Van in eastern Turkey. Changes in immunoreactivity of Na+/K+-ATPase in gill tissue and osmolarity and ion levels in plasma were investigated in C. tarichi during reproductive migration. Physicochemical characteristics and ion levels in Lake Van were high compared freshwater. Plasma osmolality and plasma ion concentrations ([Na+], [K+] and [Cl-]) increased after transfer from freshwater to Lake Van. The mitochondria-rich (MR) cells of the gill were stained in both filament and lamellar epithelia of C. tarichi by immunocytochemistry with a specific antiserum for Na+/K+-ATPase in river fish samples. Density and area of MR cells were decreased in lake-adapted fishes. These results indicated that freshwater acclimation capacity is correlated with the size and distribution of MR cells in C. tarichi, in contrast to many teleost fishes.
Hemato-Biochemical Responses of Van Fish (Alburnus Tarichi Guldenstadt, 1814) During Sublethal Exposure To Cypermethrin
(Taylor & Francis inc, 2018) Ozok, Necati; Oguz, Ahmet R.; Kankaya, Ertugrul; Yeltekin, Asli Cilingir
Cypermethrin is a highly active type II pyrethroid that is widely used to control harmful insects. The present study was conducted to investigate the possible effects of the sublethal concentration of cypermethrin (0.05L/L) on the biometric, hematological, and biochemical parameters of Van fish (Alburnus tarichi Guldenstadt 1814) for 24, 48, 72, and 96h. Behavioral and physiological changes were observed in the fish treated with cypermethrin. Hematological parameters revealed a significant decrease in the erythrocyte (RBC), hemoglobin (Hb), and hematocrit (Hct) values (p .05). Serum enzymes, aspartate aminotransferase (AST, EC 2.6.1.1), alanine aminotransferase (ALT, EC 2.6.1.2), and lactate dehydrogenase (LDH, EC 1.1.1.27) activities and serum cortisol level were significantly increased (p .05). The results showed that changes in the biometric, biochemical, and hematological values of the Van fish exposed to cypermethrin can be used as biomarkers for monitoring toxicity.
Histological Changes in the Gill Epithelium of Endemic Lake Van Fish (Chalcalburnus Tarichi) During Migration From Alkaline Water To Freshwater Tarichi
(Univ Oradea Publ House, 2015) Oguz, Ahmet R.
The gill histology of the endemic Lake Van Fish (Chalcalburnus tarichi, Pallas 1811) was compared in two different water systems during the reproductive migration from alkaline water to freshwater. The histological examination of gill samples showed that freshwater samples had a thinner primary lamella. While the cells that secrete mucous into the gills showed no volumetric change, a significant increase in their number was observed. In fish acclimated to freshwater, a small number of mucous cells was identified in the secondary lamella. Epithelial lifting was observed in both types of aquatic environments. Gill anomalies were mostly observed in the freshwater samples. Hyperplasia, lamellar fusion, vasodilation, and necrosis were observed in the gills of most fish that migrated to freshwater. The observed changes to the primary lamella, mucus cell distribution, and increase in mucous cell number in the gills may be functional in fish osmoregulation. Lesions may be related to the effects of different pollutants in a certain period, physicochemical differences, or stress caused by the two different aquatic environments. In addition, the present study is the first to demonstrate that the gills of the Lake Van fish are infected by Myxobolus parasites.
Histopathological Alterations in Van Fish (Alburnus Tarichi Guldenstadt, 1814) Exposed To Tebuconazole
(Taylor & Francis Ltd, 2022) Oguz, Elif Kaval; Ergoz, Burcu; Oguz, Ahmet R.
Tebuconazole (TEB) is one of the most commonly used fungicides in the Lake Van Basin in the Eastern Anatolia Region, Turkey, which is one of the largest alkaline lakes in the world. In this study, the effects of TEB on the Van fish, the only vertebrate species living in Lake Van were investigated. The TEB was administered at a dose of 2.5 mg/L to the Van fish, which were examined histologically via the gill, liver, and kidney tissues after 24, 48, 72 and 96 h of exposure to TEB. Normal histological structure was observed in the gill, liver, and kidney tissues in the control group. Epithelial hyperplasia, epithelial necrosis, epithelial lifting, lamellar fusion, and an increase in mucus cell counts were observed in the gill tissues of the fish exposed to TEB. Dilatation and congestion of the sinusoids, melano-macrophages aggregation, and, focal necrosis were detected in the liver tissues of the fish exposed to TEB. Bleeding in the kidney tissues, hyaline droplet degeneration, contraction of the glomerulus and enlargement of the space within the Bowman's capsule were observed. The findings of the present study indicated that sublethal concentrations of TEB result in histopathologic changes in the gill, liver, and kidney.
In Vitro Effect of Pituitary, Interrenal and Gonadal Hormones on Vitellogenin Synthesis in Primary Hepatocyte Cultures of Chalcalburnus Tarichi
(Wiley, 2015) Oguz, Ahmet R.; Unal, Guler
Vitellogenin (Vtg) is an important precursor yolk protein in egg-laying vertebrates, including fish. The 17-oestradiol (E2) plays a crucial role in the Vtg synthesis; moreover, certain hormones can stimulate Vtg synthesis. We investigated the possible role of E2, carp recombinant growth hormone (crGH), insulin (Ins), progesterone (P4) and 11-deoxycortisol (11-DOC) hormones in Vtg synthesis on primary juvenile Chalcalburnus tarichi hepatocyte culture. The amount of Vtg in the medium was measured at 2-day intervals using enzyme-linked immunosorbent assay (ELISA). The hepatocytes were maintained in culture for more than 2weeks without the addition of serum components. Vitellogenin localization was visualized with the immunofluorescence method in E2-supplemented hepatocytes. Among hormones applied to the culture, only E2 had an influence on Vtg synthesis in a time-dependent manner, while crGH, Ins, P4 and 11-DOC had no effect. However, in hepatocytes stimulated with E2 in combination with P4, a lower Vtg production was seen compared with Vtg produced when hepatocytes were stimulated with E2 alone. P4 proved to have potentiating effects on co-treatment with E2-induced Vtg production. As a result, E2 and P4 are the most important hormones for Vtg synthesis in juvenile C. tarichi hepatocyte culture.
Investigation of Gill Mucus Cells of Lake Van Fish (Alburnus Tarichi) During Reproductive Migration
(Springer, 2021) Alkan, Zehra; Oguz, Ahmet R.
Lake Van is the largest lake in Turkey. It is one of the few soda lakes in the world. Its water is brackish and soda. The lake water has a salinity rate of 19 parts per thousand and a pH of 9.8. The salty-soda content of the lake greatly limits biodiversity. Since the Lake Van fish is anadromous, it migrates from the extreme conditions of Lake Van to the freshwater pouring into the lake to spawn. In the same way, once they have emerged from the eggs, the newly hatched fish return to the lake environment to feed again. In this study, the changes in Lake Van fish gill mucus cell histochemistry were examined using different histological stains. The area and density of the mucus cells were observed to have changed in the aquatic areas of different physicochemical properties due to reproductive migration. The intensity of the mucus staining was also found to vary in different aquatic locations and gill regions. As a result, it was clearly demonstrated that mucus cell glycoprotein contents and levels found in Lake Van fish gills varied in different lake freshwater and aquatic environments. In addition, it was determined that the area and density of the mucus cells varied during reproductive migration. It is thought that the change in mucus cells was caused by salinity, pH, and bacterial and parasitic infections encountered in different aquatic environments. These changes in the gill mucus cells play an important role in the aquatic adaptation of fish.
Metal Levels in the Liver, Muscle, Gill, Intestine, and Gonad of Lake Van Fish (Chalcalburnus Tarichi) With Abnormal Gonad
(Humana Press inc, 2014) Oguz, Ahmet R.; Yeltekin, Asli
Recently, an increasing number of studies have shown that Lake Van-the biggest soda lake in the world-is polluted due to an increasing population. Studies have shown abnormalities in the Lake Van fish (Chalcalburnus tarichi), the sole fish species that inhabits the lake. Unlike the vitellogenic and mature oocytes in normal gonads, abnormal gonads show large amounts of connective tissue and young oocytes. In this study, metal levels (nickel [Ni], copper [Cu], cobalt [Co], iron [Fe], zinc [Zn], cadmium [Cd], lead [Pb], and manganese [Mn]) in the muscle, liver, gill, intestine, and gonad of Lake Van fish with normal and abnormal gonads were assessed. Further, the metal contents in the wastewater from the wastewater treatment facility situated near Lake Van in Van City were assessed. All the metal levels, except that of Zn, were high in the Lake Van environment (P < 0.05). The highest metal content in the tissues was for Fe, while the lowest level was for Co. The Pb level was found to be very high in both fish groups. Cd was not found in the tissues of both fish groups. The levels of Fe, Cu, Pb, and Mn were not significant in the tissues of both normal and abnormal fish groups. Zn level was significantly high in the livers and gonads of fish with abnormal gonads, and Co level was significantly high only in the livers (P < 0.05). Consequently, high levels of Zn in the liver and gonads and high levels of Co in the liver may be factors causing the abnormal gonads in the Lake Van fish.
Oxidative and Genotoxic Effects of Bisphenol a on Primary Gill Cell Culture of Lake Van Fish (Alburnus Tarichi Guldenstadt, 1814)
(Taylor & Francis Ltd, 2018) Oguz, Elif Kaval; Arihan, Okan; Oguz, Ahmet R.
Lake Van is the largest lake in Turkey. The lake limits lifespan due to its high pH and brackish water. For this reason, only a single species of fish (Van Fish) is living in the lake that has been adapted to these conditions. In the present study, we investigated the total oxidant status (TOS), total antioxidant status (TAS), malondialdehyde (MDA) level and DNA damage effect of bisphenol A (BPA) (10(-7), 10(-6) and 10(-5)M) on primary gill cell culture of Van Fish for 24 and 48h of incubation periods. TAS levels were not changed when compared to those of the control group, but TOS levels were decreased in both 24 and 48h. The MDA level increased only at the highest concentration (10(-5)) at the end of 12 and 24h (p<.05). DNA damage increased only at the 10(-5)M concentration after 48h. At the end of the experiment, BPA exposure caused lipid peroxidation and genotoxic effect. These results indicate that high levels of BPA exposure induced oxidative stress and DNA damage by time- and concentration-dependent fashion in the gill cell culture of Van Fish. Gill cell culture is a useful model for the rapid identification of the harmful effects of chemicals in the aquatic environment.
Polyclonal Antibody-Based Immunoassay of Vitellogenin in Van Fish (Alburnus Tarichi)
(Taylor & Francis Ltd, 2021) Oguz, Elif Kaval; Ozdemir, Kerem; Unal, Guler; Oguz, Ahmet R.
Van Lake is the third largest closed lake in the world and the biggest lake in Turkey. An ELISA method has developed with the aim of determining the pollution caused by estrogens and estrogen-like chemicals that have come to the lake Van in recent years. First, the vitellogenin in estrogen-treated male fish plasma was purified by ion exchange chromatography, injected into rats, and the obtained polyclonal antibodies were tested for specificity by Western blot and immunohistochemical methods. Immunohistochemical labeling of the vitellogenin-synthesized liver resulted in the intense marking of the liver of the animals injected with estrogen, while no markings were observed in the control group. The limit of detection of the developed enzyme-linked immunosorbent assay was 4.6 mu g L-1, and the working range was 7.8 to 2000 mu g L-1. Intra- and inter-assay variations were 13.0 % and 13.3%. The highest level of vitellogenin in male fishes measured was 23.56 mu g mL(-1).
Vitellogenin in the Male Lake Van Fish (Chalcalburnus Tarichi Pallas, 1811)
(Springer, 2015) Oguz, Ahmet R.; Kaptaner, Burak; Unal, Guler
Chalcalburnus tarichi is an endemic cyprinid species living in Lake Van, Turkey. In the present study, we investigated vitellogenin (Vtg) in the plasma of adult male C. tarichi, sampled monthly from Edremit, Campus and Carpanak sites of Van Edremit Gulf (VEG) of lake, between October 2004 and May 2005. The fish living around VEG winters in deep water around Edremit site. University and Carpanak sites are also on fish migration way from VEG to fresh water (Karasu River). The levels of measured plasma Vtg changed from trace levels to 26.35 A mu g/mL. The highest level of plasma Vtg was detected in April, with a concentration of 21.60 +/- A 1.29 A mu g/mL. We also performed immunohistochemical Vtg staining in the liver sections of male fish and determined Vtg positive hepatocytes in the liver of 1/10 sampled fish. Our results indicated that C. tarichi living in Lake Van might be exposed to endocrine-disrupting chemicals.