Burak Kaptaner

Effects of 17α-ethynylestradiol and nonylphenol on liver and gonadal apoptosis and histopathology in Chalcalburnus tarichi

Chalcalburnus tarichi is an endemic cyprinid fish living in the Lake Van basin located in the Eastern Turkey. Fish (3+ ages) were exposed to 17α‐ethynylestradiol (EE2; 1, 10, 100 ng L−1; nominal concentrations) and nonylphenol (NP; 10, 60, 200 μg L−1; nominal concentrations) for 32 days under semistatic daily renewal conditions. The exposure period was followed by an evaluation of liver and gonadal apoptosis and gonad histopathology in males and females. Exposure to the highest concentrations of EE2 (100 ng L−1) and NP (200 μg L−1) caused significant increases in the extent of apoptosis in liver and gonads. Treatment with 100 ng L−1 of EE2 and 200 μg L−1 NP increased the number of TUNEL positive hepatocytes significantly in both sexes compared to controls. The rates of apoptosis in testicular germ cells and ovarian follicular cells were significantly greater at the same concentrations. Exposure to EE2 (100 ng L−1) and NP (60 and 200 μg L−1) caused thickening of interstitial connective tissue (fibrosis) in the seminiferous tubule wall and testis‐ova formation in males. In females treated with 100 ng L−1 EE2, increased percentage of atretic ooctytes and fibrotic areas in the ovarian somatic stromal tissue were found in the ovaries. Increase in atresia, without a statistical significance, and fibrotic stromal tissue were also noted in 60 and 200 μg L−1 NP treatments. Results suggest that EE2‐ and NP‐dependent hepatotoxicity and gonadotoxicity are causally related to the increase in apoptosis in C. tarichi.

Analysis of germ cell proliferation, apoptosis, and androgenesis in the Lake Van fish (Chalcalburnus tarichi) during testicular development

In the present study, the testis histology, gonadosomatic index (GSI), germ cell proliferation and apoptosis, and the plasma 11-ketotestosterone (11-KT) and testosterone (T) levels of male Chalcalburnus tarichi were analyzed. According to the histological examinations of the specimens that were caught between February 2009 and January 2010, three testicular stages were determined. Those stages were as follows: (1) recrudescence or prespawning (July–April), (2) spawning (May–June), and (3) postspawning (July). It was observed that the GSI increased gradually, starting from the recrudescence stage, and it reached peak values at the spawning stage, while the lowest values were in the postspawning. Germ cell proliferation in the testis was detected using a proliferating cell nuclear antigen (PCNA), and germ cell apoptosis was detected by transferase dUTP nick end labeling staining. The germ cell PCNA and apoptosis index values were calculated. It was indicated that germ cell proliferation was observed in all of the testicular stages. The highest germ cell PCNA index (PI) levels were detected in July, August, and September, which then dropped in October and stabilized between February and April. The lowest PI values were detected in the spawning stage (May–June). Germ cell apoptosis was observed in all of the months, and the highest apoptotic index values were detected in August, September, October, May, and June. Plasma 11-KT and T levels were at their highest levels in May and June, and it was detected as stabile in the other months. There was a correlation between GSI, PI, and plasma androgen levels. In conclusion, the present data illustrate testicular development stages for C. tarichi and show changes in the level of GSI and sex steroid biosynthesis through spermatogenesis.

Alterations in histology and antioxidant defense system in the testes of the lake Van fish (Alburnus tarichi Güldenstädt, 1814)

Recent reports have demonstrated gonadal abnormalities in the Lake Van fish (Alburnus tarichi) from Lake Van caused by increasing pollution. In the present study, the fish was collected from an area of Lake Van receiving mainly sewage treatment plant effluent at prespawning period (April) and from a river (Karasu) which is close to the polluted area of the lake and where the fish migrates at spawning period (May). Collected specimens were examined for testicular alterations, gonadosomatic index (GSI), condition factor (CF), and antioxidant defense system biomarkers based on comparison with a reference lake (Erçek) and a reference freshwater inlet (Memedik River). Histological examinations of the testes of fish from the polluted area and the connected river showed various alterations consisting of macrophage aggregates, vacuolation, pyknosis, germ cell degeneration, seminiferous tubule dilation, disorganization of tubules, reduced spermatozoa, and fibrosis. A lower GSI and CF were also observed. Moreover, alterations in the antioxidant system biomarkers were determined in the testis tissues of fish from the Lake Van and Karasu River, indicating oxidative stress. These results suggest that the abnormalities in the testes are causally related to the increased oxidative stress, and pollution in Lake Van may have adversely affected the reproductive health of the lake Van fish.

Relation between increased oxidative stress and histological abnormalities in the ovaries of Alburnus tarichi in Lake Van, Turkey.

Recent studies have shown reproductively arrested gonad development in female Alburnus tarichi (Güldenstädt, 1814) (Cyprinidae) from the eastern coastline of Lake Van, Turkey, due to increasing pollution. In the reproductively arrested females (RAF), oocytes were developmentally blocked and arrested at the previtellogenic stage and gonadosomatic indices (GSI) were very low, while reproductively non-arrested females (RNF) found at the same site displayed relatively normal ovarian development and higher GSI. The present study investigated various oxidative stress biomarkers in the ovaries of RAF and RNF collected from a polluted site at Lake Van at the mid-vitellogenic phase, compared with reference fish from a non-polluted site (Lake Erçek). Ovarian total protein content, biometric indices, and histology were also evaluated. The oxidative stress biomarkers used were levels of lipid peroxidation (LPO) and glutathione (GSH), and activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione-S-transferase (GST). High levels of LPO and GSH and activities of SOD, GPx and GST were found in the ovaries of RAF compared with the reference fish. GSH content and activities of GPx and GST were also higher in the RNF. The total protein content and biometric indices decreased significantly in the RAF compared with the RNF and reference fish. The histology of the ovaries revealed atresia, melano-macrophage centers, encapsulated follicle cysts, and severe fibrosis in the RAF. The results of this study suggest that abnormalities in the ovaries of A. tarichi are causally related to increased oxidative stress as a result of pollution.

Cytotoxic effects of 4-octylphenol on fish hepatocytes.

The present study was conducted to determine cytotoxic effects of 4-octylphenol (4-OP) on primary cultured hepatocytes of pearl mullet (Alburnus tarichi). Lactate dehydrogenase (LDH) release, malondialdehyde (MDA) level, antioxidant enzymes [superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione-S-transferase (GST)] and glutathione (GSH) content were measured after 24-h exposure to 4-OP. 4-OP caused dose- and time-dependent increases in LDH release. Significant induction of MDA level and decrease in GSH content were found. SOD and GPx activities were decreased while GST activity was increased. These findings suggest that 4-OP leads to cytotoxicity by depressing antioxidant defenses in fish hepatocytes.

Formaldehitin Subletal Konsantrasyonlarının Sazan (Cyprinus carpio L., 1758) Balığı Üzerindeki Toksik Etkileri

Formaldehit (FA) toksik kapasitesinden dolayi akuakultur ve sus baligi yetistiriciliginde antiparazitik bir ajan ve genel bir dezenfektan olarak yaygin olarak kullanilir. Bu calisma, cok farkli kullanim alanlarina sahip olan FA’nin sazan baligi uzerindeki kronik toksik etkilerini belirlemek amaciyla yapilmistir. Ortalama agirliklari 9.8 g ve ortalama boylari 7.3 cm olan sazan ( Cyprinus carpio ) baligi, yari statik test yontemi kullanilarak, FA’ya kronik olarak maruz birakilmistir. Subletal konsantrasyonlar 0, 20, 30, 40 mg/L olarak uygulanmistir. Biyodeney 23 °C’de, 60 gun devam ettirilmistir. Analiz ve degerlendirmeler icin 15, 30 ve 60 gunde balik orneklemesi yapilmistir. Disekte edilen baliklardan alinan karaciger ve solungac dokusunda histolojik incelemeler yapilmistir. Redukte glutatyon (GSH) icerigi, glutatyon S -transferaz (GST), superoksit dismutaz (SOD), katalaz (CAT) aktivitesi karaciger ve solungac dokusunda belirlenmistir. Dokulardaki morfolojik degisiklikler, solungac primer lamellerinde yuzey epitel hucrelerinde cogalma, sekonder lamellada epitel tabakada ayrilma, karacigerde vakuolizasyon olarak tespit edilmistir. GST’nin karacigerde 40 mg/L’de 15 gunde onemli olarak genelde azaldigi; SOD’un karacigerde 20, 30 mg/L’de 15 gunde onemli olarak azaldigi; CAT’in karaciger ve solungacta 30 mg/L’de 15, 60 gunde onemli olarak degistigi gorulmustur. Bu calismayla FA’nin sazan baliginda incelenen kriterler icin hafif toksik etkiye sahip oldugu dusunulebilir. FA akuakulturde cok yaygin kullanildigindan, kontrolsuz ve gereksiz kullanimindan kacinilmasi olusabilecek olumsuz biyolojik etkilerini azaltacaktir.