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    Aldrin epoxidation in flathead Mullet (Mugil cephalus) : possible involvement of CYP1A and CYP3A
    (Wiley, 2014) Bozcaarmutlu, Azra; Turna, Sema; Sapmaz, Canan; Arınç, Emel; Karakaş, Serpil Yenisoy
    The primary objective of this study was to determine specific cytochrome P450 isozyme(s) involved in the metabolism of aldrin to its toxic metabolite dieldrin in flathead mullet (Mugil cephalus) liver microsomes. To identify the cytochrome P450 isozyme responsible for the aldrin metabolism in mullet liver, the effects of mammalian-specific cytochrome P450 inhibitors and substrates were determined in the epoxidation reaction of aldrin. CYP3A-related inhibitors, ketoconazole, SKF-525A, and cimetidine, inhibited the metabolism of aldrin. The contribution of CYP1A to the aldrin metabolism was shown by the inhibition of 7-ethoxyresorufin-O-deethylase activity in the presence of aldrin. The results indicate that CY1A and CYP3A are the cytochrome P450s involved in aldrin epoxidase activity in mullet. In addition, the suitability of aldrin epoxidase activity for monitoring of environmental pollution was also assessed in the fish samples caught from four different locations of the West Black Sea coast of Turkey.
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    Characterization of aldrin epoxidation in flathead mullet (Mugil cephalus) liver microsomes: Involvement of CYP3A
    (Elsevier Ireland Ltd, 2011) Bozcaarmutlu, Azra; Turna, Sema; Erden, Canan Sapmaz; Yenisoy-Karakaş, Serpil; Arınç, E.
    Toxic organochlorine pesticides, aldrin and its metabolite dieldrin, have been reported to contaminate the aquatic environment highly. In the present study, epoxidation reaction of aldrin to dieldrin was studied in mullet liver microsomes and contribution of cytochrome P450 isozyme(s) was determined by using specific cytochrome P450 inhibitors and substrate. Flathead mullet samples (Mugil cephalus) were caught from the West Black Sea Region of Turkey. Fish liver microsomes were prepared by differential centrifugation. Epoxidation of aldrin to dieldrin was determined by measuring the amount of dieldrin produced using gas chromatography and electron capture detector. Aldrin epoxidation was linear with time up to 60 min and with protein concentration up to 10 mg/mL. Maximal fish liver aldrin epoxidase activity was observed at pH 7.6. Aldrin epoxidase exhibited monophasic kinetics with apparent Km value of 140 μM for aldrin. The enzyme activity was inhibited approximately by 9% and 16% by methanol and DMSO, respectively. On the other hand, aldrin epoxidation was enhanced by about 113% with 2% ethanol in the incubation medium. Ketoconazole (CYP3A inhibitor), potentially inhibited the metabolism of aldrin, tolbutamide (CYP2C substrate), and alpha-naphthoflavone (CYP1A inhibitor) did not show inhibition. The results of this study strongly suggest that CYP3A is the cytochrome P450 isozyme involved in aldrin epoxidation in mullet liver microsomes whereas CYP2C and CYP1A are not involved.
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    Characterization of cytochrome P450 mediated aldrin epoxidation in mullet liver microsomes
    (Bolu Abant İzzet Baysal Üniversitesi, 2012) Turna, Sema; Bozcaarmutlu, Azra
    Organoklorlu bileşikler (OCP'ler) yağda çözünür moleküllerdir ve canlı organizmalarda birikme eğilimindedirler. Karadeniz'de OCP'lerin düzeyinin ölçüldüğü çalışmalar sınırlıdır. Bu çalışmamızda Batı Karadeniz Bölgesi'nde beş farklı lokasyondan has kefal balıkları (Mugil cephalus) 2009 yılında yakalanmıştır. Dokudan izolasyon işlemlerinden sonra, 16 farklı OCP'nin düzeyleri gaz kromatografisi ve elektron yakalama dedektörü ile ölçülmüştür. Bütün bölgelerde OCP tipi kirleticiler bulunmuştur. Bu sonuçlar bize Batı Karadeniz Bölgesi'nde OCP tipi kirleticilerin var olduğunu ve canlıların bu kimyasallara maruz kaldığını göstermiştir. Kimyasalların canlılarda birikmesi, kimyasalların biyotransformasyon reaksiyonlarına katılan enzimlere ve reaksiyona katılma düzeylerine bağlıdır. Bu çalışmamızda, aldrin'nin toksik olan metaboliti dieldrin'e dönüştürülmesi kefal karaciğer mikrozomunda çalışılmıştır. Kefal karaciğer dokularından mikrozomlar hazırlanmıştır. Mikrozomlarda aldrin epoksidaz aktivitesi, oluşan dieldrin miktarınıngaz kromotografisi ve elektron yakalama dedektörü ile ölçülmesiyle belirlenmiştir. En yüksek aldrin epoksidaz aktivitesi pH 7.6'da ve 5 mg protein konsantrasyonunda 0.5 mL reaksiyon ortamında elde edilmiştir. Aldrin epoksidaz enzimi monofazik reaksiyon kinetiği göstermiş ve Km değeri aldrin için 140 µM hesaplanmıştır. Aldrin epoksidaz aktivitesi Türkiye'nin Batı Karadeniz Bölgesi'nde beş farklı lokasyondan yakalanan balık örneklerinde optimum şartlarda ölçülmüştür. En düşük aldrin epoksidaz aktivitesi Amasra'dan yakalanan balıklarda ölçülmüştür. Zonguldak Limanı, Sakarya Nehir Ağzı ve Gülüç Irmağı Ağzı'ndan yakalanan kefal balıklarında Amasra'dan 2 kat daha fazla aldrin epoksidaz aktivitesi ölçülmüştür. Ayrıca, aldrin epoksidaz enzim aktivitesine katkısı olan spesifik sitokrom P450 enzim(leri), spesifik substrat ve inhibitörler kullanılarak belirlenmiştir. Aldrin epoksidaz aktivitesi ketokonazol (CYP3A inhibitörü), SKF-525A (CYP3A ve CYP2B inhibitörü) ve simetidin (CYP3A, CYP2C, CYP2D ve CYP1A inhibitörü) ile inhibe olurken, alfa naftoflavon (CYP1A inhibitörü), tolbutamit (CYP2C substratı), diklofenak (CYP2C substratı), orfenadrin (CYP2B6 inhibitörü) ve anilin (CYP2E substratı) ile inhibe olmamıştır. Bu sonuçlar bize CYP3A'nın aldrin epoksidaz aktivitesinde rolü bulunurken, CYP1A, CYP2C, CYP2D, CYP2B ve CYP2E'nin aldrin epoksidaz aktivitesinde rolünün olmadığını göstermiştir. Son olarak aldrin epoksidaz aktivitesi üzerine Cu+2, Cr+3, Ni+2, Tl+3, Co+3, Mg+2 ve Mn+2 metallerinin etkisine bakılmıştır. Aldrin epoksidaz aktivitesi üzerinde bakır, talyum, nikel ve krom sırasıyla %95, %22, %15 ve %13 inhibisyona sebep olmuştur.
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    Combined use of PAH levels and EROD activities in the determination of PAH pollution in flathead mullet (Mugil cephalus) caught from the West Black Sea coast of Turkey
    (Springer Heidelberg, 2015) Bozcaarmutlu, Azra; Sapmaz, Canan; Kaleli, Gizem; Turna, Sema; Karakaş, Serpil Yenisoy
    The aim of this study was to determine the extent of polycyclic aromatic hydrocarbon (PAH) pollution by measuring PAH levels and 7-ethoxyresorufin-O-deethylase (EROD) activities in flathead mullet (Mugil cephalus) samples caught from the West Black Sea coast of Turkey. The fish samples were caught in August 2008-2011. The levels of 13 PAHs were measured by high-performance liquid chromatography (HPLC) in the liver of fish. Most of the measured PAHs had three rings (low molecular weight). The frequencies of detection of PAHs were higher in fish samples caught from Zonguldak Harbour and Guluc Stream Mouth than those from Sakarya River Mouth, Amasra and Kefken. EROD activities and cytochrome P4501A (CYP1A) protein level were also measured in the fish liver microsomes. Highly elevated EROD activities and CYP1A levels were measured in the mullet samples caught from Zonguldak Harbour and Guluc Stream than those from Amasra and Kefken. The detection of PAHs in the liver of fish samples shows recent exposure to PAHs. The chemical analyses of PAHs and EROD activity results together reflected the extent of PAH pollution in the livers of fish caught from the West Black Sea coast of Turkey. The results indicate that Zonguldak Harbour is the most polluted site in the West Black Sea coast of Turkey.
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    Determination of organochlorine pesticide concentrations in flathead mullet (Mugil cephalus) caught from the western Black Sea coast of Turkey
    (Springer, 2014) Bozcaarmutlu, Azra; Turna, Sema; Sapmaz, Canan; Karakaş, Serpil Yenisoy
    The objective of this study was to determine the levels of 14 organochlorine pesticides (OCPs) in flathead mullet (Mugil cephalus) caught from the western Black Sea coast of Turkey. The fish samples were caught from five different locations of the western Black Sea coast of Turkey in August 2009. Organochlorine pesticides were extracted from the liver tissues, and then the levels of OCPs were measured using gas chromatography with an electron capture detector. Organochlorine pesticides were detected in all locations. The levels of total OCPs in fish samples ranged between 0.224 and 1.103 mu g g(-1) dry weight in the western Black Sea coast of Turkey. DDT, beta-HCH, and endosulfan I were the dominant OCPs in the fish samples. The levels of DDT in fish samples ranged between 0.081 and 0.186 mu g g(-1) dry weight. The levels of total HCH in fish samples ranged between 0.007 and 0.376 mu g g(-1) dry weight in the western Black Sea coast of Turkey. Although the usage of OCPs was banned in Turkey, the results of this study clearly indicated the presence of OCPs in the western Black Sea coast of Turkey and exposure of living organisms to these chemicals.
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    Monitoring of pollution in the western Black Sea coast of Turkey by striped red mullet (Mullus surmuletus)
    (Springer, 2020) Bozcaarmutlu, Azra; Sapmaz, Canan; Can, Gizem Kaleli; Turna, Sema; Aygün, Züleyha; Arınç, Emel
    The striped red mullet (Mullus surmuletus) is an economically important demersal fish species. In this study, our aim was to monitor the pollution in the western Black Sea coast of Turkey using striped red mullet as a bioindicator species. Fish samples were caught from four different locations in the western Black Sea coast of Turkey in 2006, 2009-2011, and 2016. Highly elevated cytochrome P4501A (CYP1A)-related 7-ethoxyresorufin O-deethylase (EROD) activities were measured in striped red mullet caught from Zonguldak Harbor in all of the sampling years. The lowest EROD activities were measured in fish samples caught from Kefken. In addition to the EROD activity measurements, glutathione S-transferase (GST), glutathione reductase, and catalase activities were also measured in the striped red mullet samples. Higher GST and catalase activities were measured in the striped red mullet samples caught from Zonguldak Harbor than from Kefken in 2016. These results indicate that the striped red mullet is responsive to CYP1A inducer pollutants. This study covers intermittent measurements of the biomonitoring data from the striped red mullet caught around the western Black Sea coast of Turkey, over a 10-year period.