Browsing by Author "Oguz, A. R."

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Determination of Hormones Inducing Oocyte Maturation in Chalcalburnus Tarichi (Pallas, 1811)
(Springer, 2008) Unal, G.; Erdogan, E.; Oguz, A. R.; Kaptaner, B.; Kankaya, E.; Elp, M.
Chalcalburnus tarichi is an endemic cyprinid species living in the Lake Van basin, in eastern Anatolia, Turkey. The present study was undertaken to determine which hormones induce oocyte maturation in C. tarichi. The levels of 17 alpha,20 beta,21-trihydroxyprogesterone (20 beta-S), progesterone (P), 17 alpha-hydroxyprogesterone (17 alpha-HOP), 11-deoxycortisol (11-DOC), and 17 alpha-hydroxy-20 beta-dihydroprogesterone (17,20 beta-P) were measured in fish caught from Lake Van and the Karasu River, and injected with human chorionic hormone (hCG) (1,000 and 1,500 IU/kg). Oocytes of fish caught from the lake were also incubated in vitro with different doses (50, 200, and 1,000 ng/ml) of 20 beta-S, 17 alpha-HOP, 11-DOC, and 17,20 beta-P. 11-DOC was found to be the most effective hormone among those measured for inducing oocyte maturation in vivo and in vitro. 17,20 beta-P could not be determined in the plasma of any fish in vivo (P < 0.05). 1,000 IU/kg dose of hCG given by injection caused a statistically significant increase in all plasma hormone levels (P < 0.05). It was found that there was a significant decrease in the P level only at 1,500 IU/kg dose of hCG injected (P < 0.05), while the level of other hormones increased at this dose (P < 0.05). It was also determined that all the hormones were effective in germinal vesicle breakdown (GVBD) in in vitro oocyte culture (P < 0.05). However, 11-DOC was found to be the most effective hormone in GVBD at a dose of 200 ng/ml (70% GVBD). In conclusion, 11-DOC synthesized during final oocyte maturation in C. tarichi was found to be a potent inducer of GVBD, which shows that 11-DOC may be described as an oocyte maturation steroid in this species.
Determination of Plasma Vitellogenin Levels and Localization of Vitellogenin in Liver of Lake Van Pearl Mullet (Chalcalburnus Tarichi Pallas, 1811)
(Iranian Fisheries Science Research inst-ifsri, 2015) Oguz, A. R.; Unal, G.; Kaptaner, B.
This study focused on hepatosomatic and gonadosomatic index and levels of plasma 17 beta-estradiol (E-2), vitellogenin (Vtg) and total protein and determined the localization of Vtg in the liver during vitellogenesis in female Chalcalburnus tarichi, an endemic cyprinid species living in the Lake Van, Turkey. The levels of plasma E-2, Vtg and total protein in female fish increased during vitellogenesis and they are positively correlated with each other. According to the results from the female fish, the lowest levels of E-2 and Vtg were measured in December at 120.60 +/- 23.38 pg ml(-1) and 1.10 +/- 0.26 mg ml(-1), respectively. The highest levels of plasma E-2 and Vtg were in May (833.40 +/- 211.58 pg ml(-1)) and April (31.31 +/- 4.9 mg ml(-1)), respectively. The Vtg-positive hepatocytes were not uniform in liver of fishes. Generally, the hepatocytes surrounding the portal and central veins were strongly Vtg positive. These results showed that plasma Vtg levels in female fish increased during vitellogenesis related to plasma E-2 and gonadosomatic index.
Gonadal Histology and Some Biochemical Characteristics of Chalcalburnus Tarichi (Pallas, 1811) Having Abnormal Gonads
(Springer, 2007) Unal, G.; Turkoglu, V.; Oguz, A. R.; Kaptaner, B.
The gonad histology, gonado-somatic index (GSI), 17 beta-estradiol (E-2) levels and acetylcholinesterase (AChE) activity in the carp species Chalcalburnus tarichi from Lake Van and the Karasu river, eastern Turkey, have been investigated. Fish between 5 and 7 years old were sampled from November 2003 to February 2004. The ratio of female fish caught in Lake Van with abnormal ovaries (AbOF) was 43.3%, but the fork length and body weight of these fish were not correlated with this abnormality. The weight of the ovaries and the GSI values of AbOF were very low (P < 0.05). Histological observations on the samples caught each month revealed that the oocytes had degenerated in the perinucleolus and early cortical alveolus stages and that the ovaries were full of somatic stromal tissue. In addition, the seminiferous tubules of male fish with abnormal testes did not contain male reproductive cells at any stage. The ovaries of the fish caught from the Karasu river were also full of oocytes in the perinucleolus and early cortical alveolus stages, but there were fewer atretic follicles. Furthermore, apoptosis was observed in the ovary cells of these fish, in particular in the follicular cells, and the plasma E-2 levels of the AbOF was very low (P < 0.05). AChE activity was inhibited only in liver (P < 0.05). We conclude that our sample of C. tarichi must have been exposed to various polluting chemicals or another unknown factors (such as global warming) and that these factors have irreversibly impaired oocyte development in a high percentage of fish.
A Histological Study of the Kidney Structure of Van Fish (Alburnus Tarichi) Acclimated To Highly Alkaline Water and Freshwater
(Taylor & Francis Ltd, 2015) Oguz, A. R.
Kidneys are important organs that play a role in ion and water regulation in different aquatic environments. The Van fish (Alburnus tarichi, Guldenstadt, 1814) has acclimated to the alkaline waters of the largest saline soda lake in the world. In this study, changes in kidney tissue were examined histologically in alkaline and freshwater as the fish entered freshwater for reproduction. In addition, immunological changes were examined for Na+, K+, ATPase (NKA), an important transmembrane protein in kidneys. A histological comparison of the kidneys of fish taken from both environments was made. The glomerular volume was larger in fish acclimated to freshwater, and the collecting tubules were larger in diameter and had thicker walls. The fish acclimated to alkaline lake water had reduced numbers of glomeruli of smaller size. NKA enzyme was present in tubules within kidneys in both environments. It was, however, observed more frequently in fish acclimated to freshwater. Although plasma osmolality and Cl- values decreased in the fish acclimated to freshwater, hematocrit values increased (p<0.05). No changes were observed in the muscle water content between alkaline water- and freshwater-acclimated fish. We clearly demonstrate that histologic and immunochemical changes take place in the kidney of the Van fish acclimated to the different physicochemical characteristics of alkaline and freshwater environments.
Some Macro and Trace Elements in Various Tissues of Van Fish Variations According To Gender and Weight
(Arquivo Brasileiro Medicina veterinaria Zootecnia, 2018) Yeltekin, A. C.; Oguz, A. R.
Van fish is a fish that can live in soda water at pH 9-10. Van fishing area is a very important source of protein for the people. The variations in tissue metal levels according to gender and weight in Van fish (Alburnus tarichi, Guldenstadt 1814) were studied. This study was conducted for the first time in Van fish. Which it is very important for living organisms Calcium(Ca), magnesium(Mg), sodium(Na), potassium(K), cobalt(Co), chromium(Cr) and lithium(Li) elements levels in the muscle, liver, gill, gonad, and brain tissues of Van fish were investigated by using inductively-coupled plasma-optic emission spectroscopy (ICP-OES). The results were evaluated in two groups as macro-elements(Ca, Mg, Na, K) and trace-elements(Co, Cr, Li). Cobalt concentration in brain tissue was found to be higher than those in other tissues. Also, male fish had higher metal concentrations than female fish and their metal levels in brain and gonad tissues varied with their weight (P<0.05). This study shows that consumption of Van fish can be consumed to supply some necessary minerals required for a healthy nutrition.