Browsing by Author "Oguz, Ahmet Regaib"

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Anatomical and Histological Investigation of the Pineal Gland in the Lake Van Fish (Alburnus Tarichi (Guldenstadt, 1814))
(Wiley, 2022) Orgi, Elif; Oguz, Ahmet Regaib
The pineal gland and melatonin secreted from the gland regulate the biological clock and adaptation to seasonal changes, glucose balance, nutrition and locomotor activities. In this study, the pineal gland of the Lake Van fish was examined anatomically and histologically. The melatonin level secreted from the pineal gland was determined in fish plasma sampled from both lakes and streams during reproduction migration. The pineal gland in the Lake Van fish, as in other teleost fish, is located in the head, under the translucent pineal window, which does not contain many pigment cells. The gland consists of pineal vesicle and pineal stalk parts on the dorsal sac in the Lake Van fish. It was determined that the pineal gland showed good vascularity. The presence of pinealocytes and different types of cells in the pineal organ was determined histologically. Pinealocytes were intensely localized in the lumen of the pineal vesicle. The plasma melatonin level increased in fish passing from lake to stream for reproductive migration.
Antioxidant Responses and Dna Damage in Primary Hepatocytes of Van Fish (Alburnus Tarichi, Guldenstadt 1814) Exposed To Nonylphenol or Octylphenol
(Taylor & Francis Ltd, 2018) Yeltekin, Asli Cilingir; Oguz, Ahmet Regaib
Alkylphenols, a nonionic surface-active agent group, such as nonylphenol (NP) and octylphenol (OP) are important endocrine-disrupting chemicals (EDC). In this study, the dose- and time-dependent effects of NP and OP were investigated in the primary hepatocyte culture of Van Fish. In this study, samples were taken at different times and biochemical parameters were studied separately. The effects of the chemicals used on SOD, CAT, GSH-Px, MDA, and 8-OHdG were investigated in hepatocyte culture. The antioxidants SOD and CAT were observed to increase in all groups in the primary hepatocyte cultures at the 24th hour after NP and OP administration, whereas the GSH-Px level was observed to increase with OP at the 24th hour and with NP at the 48th hour. The MDA level was observed to reach its highest value for both chemicals in the 24th hour, and the 8-OHdG level was observed to increase toward the end of the follow-up time, compared to the control group (p < 0.05). In conclusion, different doses of NP and OP were found to induce an increase in the levels of antioxidants and the MDA level in Van Fish primary hepatocyte culture. DNA damage, on the other hand, may be considered to appear after longer-term exposure to NP and OP.
The Effects of 17α-Ethynylestradiol, 4-Nonylphenol and Phenol Red on Vitellogenin Synthesis in Juvenile Chalcalburnus Tarichi Primary Hepatocyte Culture
(Sage Publications inc, 2011) Oguz, Ahmet Regaib; Unal, Guler
In this study, the effects of the endocrine-disrupting chemicals known as 17 alpha-ethynylestradiol (EE2), 4-nonylphenol (NP) and phenol red on vitellogenin (Vtg) synthesis in juvenile Chalcalburnus tarichi primary hepatocyte culture were investigated depending on dose and time. Hepatocytes were isolated by collagenase perfusion method and the cells were kept alive in cell culture for more than 2 weeks without using serum. As a result, it was determined that EE2 increased the Vtg synthesis depending on dose and time (p<0.05), while NP and phenol red did not have any effect on the Vtg synthesis in the Chalcalburnus tarichi primary hepatocyte culture. Besides that, it was observed that high doses of NP (10(-3) and 10(-4) M) had toxic effects to the hepatocyte culture, too.
Effects of Chlorpyrifos on Primary Gill Cell Culture of Lake Van Fish (Alburnus Tarichi Guldenstaadt 1814)
(Oxford Univ Press, 2020) Oguz, Ahmet Regaib; Oguz, Elif Kaval; Ozok, Necati
Lake Van fish (Alburnus tarichi Guldenstadt 1814) is the only fish that can adapt to the extreme conditions (pH 9.8 salinity 0.2% and alkalinity 151.2 meq/L) of Lake Van. In this study, it was aimed to determine the cytotoxic and genotoxic effects of chlorpyrifos (CPF) on Lake Van fish primary gill cell culture. Gill epithelium from Lake Van fish was isolated enzymatically and grown in primary culture on Leibovitz's L-15 medium. After different doses (0.01, 0.1, 1, and 10 mu M) of CPF were applied to the gill cells, the total oxidant status (TOS), total antioxidant status (TAS), malondialdehyde (MDA), and DNA damage levels (8-hydroxyguanine (8-OHdG)) were examined at the end of 24 and 48 h. It was determined that the TOS, MDA, and 8-OHdG levels increased in the cells exposed to high doses (1 and 10 mu M) of CPF and the TAS was decreased (P < 0.05). It was revealed from this study that CPF administered at a dose higher than 1 mu M can cause oxidative stress and DNA damage in the primary gill cell culture of Lake Van fish. In addition, the findings showed that Lake Van fish primary gill cell culture was useful in determining the effects of toxic substances likely to be the contaminants of a lake. [GRAPHICS]
Histopathological Determination of Changes in Tissues of Lake Van Fish (Alburnus Tarichi (Güldenstädt, 1814)) Exposed To Esfenvalerate
(Taylor & Francis Ltd, 2024) Oguz, Elif Kaval; Alkan, Zehra; Oguz, Ahmet Regaib; Azizoglu, Burcu Ergoz; Orgi, Elif
Esfenvalerate is a widely used pesticide of the pyrethroid insecticide group. It is a hydrophobic pesticide with toxic effects on many aquatic organisms. In this study, the damage caused by esfenvalerate 0.158 mu g/L administered sublethally to the gills, liver, and kidneys of Lake Van fish was determined histopathologically. Lesions such as necrosis, hyperplasia, epithelial lifting, hypertrophy, and haemorrhage were observed in the gills exposed to esfenvalerate. Gill goblet cells increased after 24 h and decreased on the other days of esfenvalerate exposure. Histopathological changes such as haemorrhage, hypertrophy, necrosis, and cloudy degeneration were observed in the liver. In the kidneys, lesions such as haemorrhage, necrosis, cell degeneration, Bowman's capsule enlargement, and glomerulus atrophy were detected. These lesions increased in tissues depending on the length of application of esfenvalerate. As a result of this study, it was determined that esfenvalerate caused damage to the gills, liver, and kidneys in Lake Van fish depending on time. These anomalies observed in the gills, liver, and kidneys can be used as a bioindicator of esfenvalerate contamination in Lake Van.
Histopathology and Immunohistochemistry of Gills of Van Fish (Alburnus Tarichi Guldenstadt, 1814) Infected With Myxosporean Parasites
(Taylor & Francis Ltd, 2020) Oguz, Ahmet Regaib; Oguz, Elif Kaval
The Van fish are a cyprinid species endemic to Turkey's largest soda lake, Lake Van, and have great economic value because they are a food source. Once a year, the fish take part in reproductive migration to the fresh waters flowing into the lake. The fish migrate from an extreme environment with high salinity (2.2%) and high pH (9.8). These fish are unable to reproduce in this alkaline environment and must migrate to fresh water during their breeding season. The aim of the present study is to report the presence of the myxosporean parasites on the gills and the pathological changes. Changes in gill histopathology, mucocytes, mitochondria-rich cells, expression of Heat Shock Protein 70 (Hsp70), and ATPase (NKA) were observed in the gill tissue. As a result of the histopathological changes in gills, infected fish had abundant plasmodia with different sizes. Plasmodia were found on gill filaments inside white ovoid-shaped structures. It was observed that plasmodia were contained on the primary filament which changed the histological structure of the gill tissue to a large extent. It was determined that the density and size of mucocytes in the infected areas of the gill tissue increased, whereas the number of mitochondria-rich cells decreased. Hsp70, an indicator of stress, was not different between normal and infected fish.
Immunohistochemical Examination of Hsp70, Pcna, 8-Ohdg, Inos and Apoptosis in the Gills of Lake Van Fish (Alburnus Tarichi (Güldenstädt, 1814)) After Esfenvalerate Exposure
(Taylor & Francis Ltd, 2025) Cekic, Zehra Alkan; Orgi, Elif; Oguz, Ahmet Regaib; Otun, Yagmur
Lake Van fish is an endemic carp species adapted to the soda waters of Lake Van. As a result of agricultural and livestock activities around the lake, many environmental pollutants are dumped into the lake as waste. Esfenvalerate is a pyrethroid pesticide used extensively in agricultural areas in the region. In this study, Lake Van fish were exposed to a sublethal dose of esfenvalerate (0.158 mu g/L) for 24, 48, 72, and 96 hours, and their gill tissues were examined immunohistochemically. Histopathological analysis determined that hyperplasia and necrosis occurred in the gill tissue as a result of exposure. Additionally, the heat shock protein 70 (HSP70), proliferating cell nuclear antigen (PCNA), 8-hydroxy-2' -deoxyguanosine (8-OHdG), and nitric oxide synthase (iNOS) positive cells and the number of apoptotic cells were determined by immunohistochemistry in gills of Lake Van fish exposed to esfenvalerate. The density of cells containing HSP70 and PCNA increased at 24 and 48 hours of exposure to esfenvalerate. 8-OHdG occurred in gill tissue as a result of esfenvalerate exposure, and the number of damaged cells increased over time. The number of apoptotic cells and containing the inducible isoform of iNOS increased in the gill tissue as a result of esfevalerate exposure. Overall, it was determined that esfenvalerate had a toxic effect on Lake Van fish gills.
Investigation of Some Hormones Affecting Osmoregulation of Lake Van Fish (Alburnus Tarichi) During Reproductive Migration
(Wiley, 2022) Yesilbas, Ayse; Oguz, Ahmet Regaib
Lake Van is one of the largest soda lakes in the world. The extreme characteristics of the lake greatly limit the animals living there. Lake Van fish (Alburnus tarichi Guldenstadt, 1814) is the only vertebrate species that has adapted to this environment. Lake Van fish migrate to freshwater every year to breed, after which, they return to the lake environment. The fish are exposed to different aquatic environments during migration. The endocrine mechanisms involved in the physiological changes during this migration are not studied in this species, yet. In this study, water and serum sodium, potassium and chloride levels in the lake, downstream and upstream to which Lake Van fish are exposed during reproductive migration were determined. Circulating cortisol, free triiodothyronine, free thyroxine, insulin-like growth factor-I, growth hormone and prolactin levels were also investigated. It was observed that the water ion levels decreased in the freshwater localities when compared to the lake localities, and the serum Na+ and Cl- levels decreased in upstream1 and upstream2, K+ levels stayed at a certain level in all localities. It was determined that the hormone levels differed in the upper regions of the river (upstream1 and upstream2), where spawning was completed, from the lake environment, where reproductive migration began. Results indicate that the studied hormones had direct and indirect effects on osmoregulation in the Lake Van fish with the physiological tendency to keep osmotic homeostasis, as occurs in other teleost species.
Investigation of the Therapeutic Effect of Melatonin on Deltamethrin Applied Mouse Primary Hepatocyte Culture
(Taylor & Francis Ltd, 2025) Kaval Oguz, Elif; Oguz, Ahmet Regaib; Ozok, Necati; Alkan, Zehra; Ergoz Azizoglu, Burcu; Orgi, Elif; Yesilbas, Ayse
ObjectiveIn recent years, it has been known that the melatonin hormone, secreted from the pineal gland, possesses significant antioxidant activity. This study explores the therapeutic effect of melatonin on the deleterious effects of deltamethrin, a pyrethroid pesticide extensively used worldwide, including in T & uuml;rkiye, on mouse liver cells.MethodsHepatocytes from Balb/C mice were isolated using a two-stage perfusion method, resulting in over 85% live hepatocytes. The isolated cells were cultured with different doses of deltamethrin (1 and 10 mu M) and melatonin (100 mu M) for 24 and 48 hours. At the conclusion of the culture period, hepatocytes were extracted at the 24th and 48th hours, and Malondialdehyde (MDA), Total Antioxidant Capacity (TAC), Total Oxidation Status (TOS), and DNA damages (8-hydroxy-2'-deoxyguanosine (8-OHdG)) were examined.ResultsWhile an increase in MDA, TOS, and DNA damage was observed in the deltamethrin-administered groups of hepatocytes, a decrease in TAC level was noted. It was determined that the applied deltamethrin had no effect on cell viability throughout the application period.ConclusionFurthermore, it was observed that melatonin, when administered concurrently with deltamethrin, reduced the toxic effect of deltamethrin. This study suggests that melatonin has a protective effect against deltamethrin-induced damage in mouse hepatocyte cells.