Browsing by Author "Unal, Guler"

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Apoptosis in Postovulatory Follicles of Chalcalburnus Tarichi Pallas, 1811
(Ege Univ, 2006) Kaptaner, Burak; Unal, Guler
In the present study, apoptosis in postovulatory follicle was investigated with TUNEL staining and agarose gel electrophoresis methods, and plasma 17 beta-estradiol (E2) level was determined at the 1st, 3rd and 5th day after ovulation in Chalcalburnus tarichi. Apoptotic cells were labelled in postovulatory follicles in histological sections on the 1st day after ovulation and it is indicated that apoptosis was observed mainly in granulosa cells and scarcely in theca cells. Oligonucleosomal length DNA fragmentation which is hallmark of apoptosis was observed on the days 1, 3 and 5 after ovulation. While no oligonucleosomal DNA fragmentation was observed on the ovulation time, it was observed that this fragmentation was remarkable on the days 3 and 5. Plasma E-2 level decreased gradually after ovulastion. This decrease was significant on the days 3 and 5 (P<0.05). These results demonstrate that apoptosis is responsible for elimination of postovulatory follicles however it was considered that low level of E-2 after ovulation, accelerates the postovulatory follicle apoptosis in Chalcalburnus tarichi.
Effects of 17α-Ethynylestradiol and Nonylphenol on Liver and Gonadal Apoptosis and Histopathology in Chalcalburnus Tarichi
(Wiley, 2011) Kaptaner, Burak; Unal, Guler
Chalcalburnus tarichi is an endemic cyprinid fish living in the Lake Van basin located in the Eastern Turkey. Fish (3+ ages) were exposed to 17 alpha-ethynylestradiol (EE2; 1, 10, 100 ng L-1; nominal concentrations) and nonylphenol (NP; 10, 60, 200 mu g 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 mu g L-1) caused significant increases in the extent of apoptosis in liver and gonads. Treatment with 100 ng L-1 of EE2 and 200 mu g 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 mu g 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 mu g 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. (C) 2010 Wiley Periodicals, Inc. Environ Toxicol 26: 610-622, 2011.
Effects of 17α-Ethynylestradiol on Hepatosomatic Index, Plasma Vitellogenin Levels and Liver Glutathione-S Activity in Lake Van Fish (Chalcalburnus Tarichi Pallas, 1811)
(Parlar Scientific Publications (p S P), 2009) Kaptaner, Burak; Kankaya, Ertugrul; Unal, Guler
17 alpha-ethynylestradiol (EE2), a synthetic estrogen used in birth control pills, has frequently been detected in aquatic environments. In the present study, male and female individuals (3+ ages) of Chalcalburnus tarichi, an endemic cyprinid fish living in the Lake Van basin located in the eastern Anatolia region of Turkey, were exposed to nominal concentrations of 1, 10, and 100 ng/L EE2 for 32 days at semistatic daily renewal conditions. After exposure, plasma vitellogenin (Vtg), hepatosomatic index (HSI), and liver glutathione-S-transferase (GST) activity were examined. Plasma Vtg concentrations exhibited significant inductions in all doses of EE2 in both sexes. HSI did not change at the 1 and 10 ng/L EE2 concentrations; it, however, significantly increased after 100 ng/EE2 exposure in males and females. Liver GST activity significantly increased in females at the 1 ng/L EE2 exposure, whereas it did not change in males. On the other hand, GST activity was inhibited in both sexes at the 10 and 100 ng/L EE2 exposures. The results of this study indicate that C tarichi is highly suspectible to EE2 and its detoxification capability may be weakened by EE2-inhibiting phase II enzyme, GST.
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.
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.
Induction of Micronuclei in Chalcalburnus Tarichi (Pallas, 1811) Exposed To Sub-Lethal Concentrations of Methyl Parathion
(Parlar Scientific Publications (p S P), 2012) Kankaya, Ertugrul; Arslan, Ozlem Cakal; Parlak, Hatice; Unal, Guler
The micronucleus assay (MNT) is a mutagenicity test system for determining pollution and chemicals causing changes in DNA fragments, such as micronuclei (MN) in the cytoplasm of interphase cells. Damage caused in the DNA by genotoxic pollutants is the first consequence occurring in the aquatic organisms. The MNT in fish erythrocytes has increasingly been used to detect the genotoxic effects of environmental mutagens, and its frequency is considered to reflect the genotoxic damage to cells, mainly the chromosomes. In this study, the genotoxic effects of methyl parathion (MP), one of the most commonly used pesticides in Lake Van Basin, on Chalcalburnus tarichi (Pallas, 1811), which is an economically important endemic species in the basin, were investigated. The experiment was carried out over a period of 30 days using an in vivo method on samples of peripheral erythrocytes of C. tarichi taken at sampling times. The fish were exposed to increasing concentrations of MP (1.47, 2.1, 3.0, 4.28 and 6.11 mg L-1) under semi-static conditions in the laboratory. The increase in micronucleus frequency was significant as well as altered cells' frequencies. Thus, it was attempted to determine whether MP affected the erythrocytes of C. tarichi at the level of DNA by means of the MN test. According to the results of the present study, the highest level of frequency of MN was found at 6.11 mg L-1. In conclusion, this study indicates that the MN test gives sensitive results in determining the genotoxicity of pesticides, and thus, it might be used as a standard method for regularly monitoring the genotoxic effects of pesticides.
An Investigation on Endoparasites of Rana Ridibunda Complex (S. I.) With Dermal Parasite (Metacercariae) in Dalaman (Turkey)
(Triveni Enterprises, 2007) Unal, Guler; Saygi, Gulendame; Ayaz, Dincer; Tok, Cemal Varol
In this study, endoparasites of the Rana ridibunda specimens collected from Dalaman area, southwestern Turkey were investigated. In the intestine of 17 specimens of R. ridibunda, five different parasites, represented by three species of the trematoda (Diplodiscus sp, Pleurogenoides sp, Plagiorchis sp) and two genera of round worms (Cosmocerca sp; Foleyella sp) were recognized. The trematoda and one of the round worms were found in the rectal region whereas the other round worm species are observed in the abdominal cavity.
Isolation of Estrogen Receptor Subtypes and Vitellogenin Genes: Expression in Female Chalcalburnus Tarichi
(Elsevier Science inc, 2014) Unal, Guler; Marquez, Emily C.; Feld, Mara; Stavropoulos, Pericles; Callard, Ian P.
Reproductively arrested gonadal development has been previously described in the teleost 'pearl mullet (Chalcalburnus tarichi, Cyprinidae) from Van Edremit Gulf of Lake Van, Turkey. Oocyte development in some females was arrested at the previtellogenic stage, while gonadosomatic index (GSI) and plasma 17 beta-estradiol (E-2) level were low. A subset of the females was found to have normal ovaries and relatively higher plasma Ey and GSI. These two groups were termed reproductively arrested (RA) and reproductively non-arrested (RN) females. In this study, we cloned estrogen receptor (ER) isoforms (ER alpha, ER beta 1 and ER beta 2) and vitellogenin (Vtg), and their mRNA levels were measured in RA and RN fish tissues. C tarichi ERs fell in the same clade with other fish ERs and ERa and ER beta 1 had 97% and 98% identity with the roach (Rutilus rutilus) ERs, respectively. Both Vtg and ER isoforms' mRNA abundance were higher in the liver than in the ovary and hypothalamus (liver > ovary > hypothalamus). The level of ERa mRNA was significantly lower in the liver, ovary and brain of RA fish than in the RN fish tissues. ER beta 1 mRNA levels were not different in the liver and ovary from RA and RN fish while ER)32 expression significantly increased in the liver and ovary from RA fish. All ER subtype expression was found to be lower in the brain from RA fish than RN fish. The level of Vtg mRNA was significantly lower in the liver and ovary from RA fish than RN fish tissue. These results suggest that ER subtypes are differentially regulated by Ey, and their functions are also different in vitellogenesis. Analysis of organic contaminants in sediments revealed that C tarichi living in Van Edremit Gulf of Lake Van are exposed to the contaminants bis(2-ethylhexyl) phthalate and 4,4' DDT. We suggest that the RA fish represent a segment of the population that is more sensitive to exposure to endocrine disrupting compounds. (c) 2014 Elsevier Inc All rights reserved.
Levels of Some Ovarian Hormones in the Pre- and Post Spawning Periods of Chaicalbumus Tarichi Pallas, 1811, and the Postovulatory Structure of Follicles
(Tubitak Scientific & Technological Research Council Turkey, 2006) Unal, Guler; Karakisi, Hatice; Elp, Mahmut
The structure of postovulatory follicles and the levels of ovarian 11-dehydrocorticosterone (11-DHC), estradiol-17 beta (E-2), 17 alpha-hydroxyprogesterone (17 alpha-OH-P), and progesterone (P), before and after spawning, were studied in Chalcalburnus tarichi. It was observed that postovulatory follicles are characterized by a highly vascular thecal layer and hypertrophied granulosa cells containing dense smooth endoplasmic reticulum, many large mitochondria with tubular cristae, and lipid droplets. Ovary 11-DHC level was low in the pre- and post-spawning periods (38.3 +/- 4.9-22.3 +/- 2.6 ng/ml). The level of E-2 was 216.8 +/- 31.1 ng/ml before spawning. This hormone declined on the 1(st) and 5(th) day after spawning and increased again to the level of 216.8 +/- 6.7 ng/ml on the 10(th) day; however, the E-2 level decreased significantly on the 15(th) day (61.5 +/- 17.8 ng/ml) (P < 0.01). The 17 alpha-OH-P level was low (84.5 +/- 49.4 ng/ml) before spawning and reached a peak (295.7 +/- 52.5 ng/ml) on the 10(th) postspawning day, but a slight decline was observed on the 15(th) day (190 +/- 21.5 ng/ml) (P > 0.01). The P level was low (23.4 +/- 18.3 ng/ml) before spawning. Its level began to increase after spawning and reached a peak on the 10(th) postspawning day (200.7 +/- 29.1 ng/ml) (P < 0.01), but declined significantly on the 15(th) day (63.2 +/- 19.5 ng/ml) (P < 0.01). The results obtained from this study indicate that: a) In the postovulatory follicles, the granulosa cells produce steroids; b) 11-DHC has no effect before or after spawning; c) E-2 induces spawning; d) 17 alpha-OH-P and P have an effect after spawning. It can be concluded that the apoptotic cells in postovulatory follicles increased on the 1 5th day, at which time E, and P hormones were at their lowest levels after spawning in C. tarichi.
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).
A Trematode Parasite Infecting the Skin of Rana Ridibunda Complex (Sensu Lato) From Dalaman (Mugla, Turkey)
(Taylor & Francis inc, 2010) Unal, Guler; Ayaz, Dincer; Tok, Cemal Varol; Saygi, Gulendame
We examined the structure of the black spots on the ventral surface of Rana ridibunda specimens, which were collected from the west Anatolia region of Turkey, and a multi-cellular parasite was discovered under these spots on the dermis within a cyst. The number of melanocytes had increased and the connective tissue of the dermis had surrounded the cyst. The parasite was a trematode in its metacercarial stage.
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.