Ahmet Regaib Oguz

Van Yuzuncu Yil University

Synthetic detergents which have a major role in environmental pollution accumulate over time and reach levels that harm nature. The surfactants which are abundantly used as cleaning components are discharged into the Van Lake with the sewage water. These chemicals accumulating in the lake may reach a level that could affect the only fish species of...

The histology of the pituitary gland was investigated in the Lake Van fish (Alburnus tarichi). The adenohypophysis (AH) is composed of the rostral pars distalis (RPD), proximal pars distalis (PPD), and pars intermedia (PI). Seven different cell types were identified in the AH. Most of the cells in the RPD were periodic acid-Schiff (PAS)-negative. I...

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 pla...

Tebuconazole (TEB) is one of the most commonly used fungicides in the Lake Van Basin in the Eastern Anatolia Region, Turkey, which is one of the largest alkaline lakes in the world. In this study, the effects of TEB on the Van fish, the only vertebrate species living in Lake Van were investigated. The TEB was administered at a dose of 2.5 mg/L to t...

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 Güldenstädt, 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...

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 chrom...

Lake Van is the largest lake in Turkey. It is one of the few soda lakes in the world. Its water is brackish and soda. The lake water has a salinity rate of 19‰ and a pH of 9.8. The salty-soda content of the lake greatly limits biodiversity. Since the Lake Van fish is anadromous, it migrates from the extreme conditions of Lake Van to the freshwater...

Fluorine toxicity has negative effects on soft tissue besides skeletal and dental tissues. In the present study, we have investigated the protective effect of chitosan (CS) and chitosan oligosaccharide (COS) on liver tissue of fluorine-intoxicated rats taking the antioxidant characteristics of chitosan and its derivatives into consideration. In thi...

Background. Lake Van, the second-largest soda lake in the world, has a pH 9.8 value. A fish, locally known as Van fish, Alburnus tarichi (Güldenstädt, 1814), is an endemic fish of Lake Van and known also as pearl mullet, tarek, or Van bleak. Tebuconazole is a widely used pesticide around Lake Van. In this study, we will focus on the effects of tebu...

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 w...

Van fish, an anadromous fish, migrate in flocks to fresh water poured into the lake from the extreme conditions of Van Lake for breeding. The fish that complete their breeding return to the lake for feeding. In these two different aquatic environments, skin is exposed to different physicochemical effects of water. In the present study, morphometric...

Deltamethrin is a widely used pyrethroits worldwide. Although the chemical is used to combat insects, it has effects on other non-target organisms. Deltamethrin is extensively used in agriculture, animal husbandry, and domestic areas in the Lake Van basin. The aim of this study was to determine the cytotoxic, genotoxic, and oxidative damage from de...

Objective: The aim of this study is to determine the effect of phthalate on the early larval development of Alburnus tarichi. Methods: The larva (2 days after hatching) of Alburnus tarichi were exposed to 0.1, 1, and 10 μg/L phthalate for 6 days (during yolk sac nutrition), and the levels of estrogen receptor alfa, beta-1 and beta-2, and aromatase...

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 a...

Van Balığı, Türkiye’nin en büyük gölüne endemik anadrom bir türdür. Balıklar, her sene üremesini gerçekleştirmek için alkali Van Gölü’nden göle dökülen tatlı sulara göç ederler. Balık bu göç sırasında açlık, tuz ve pH adaptasyonu gibi farklı stres faktörlerine maruz kalır. Bu çalışmada, Van Balığının üreme göçü öncesi ve sonrasında plazma, solungaç...

Lake Van is the largest lake in Turkey. The lake limits lifespan due to its high pH and brackish water. For this reason, only a single species of fish (Van Fish) is living in the lake that has been adapted to these conditions. In the present study, we investigated the total oxidant status (TOS), total antioxidant status (TAS), malondialdehyde (MDA)...

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...

Cypermethrin is a highly active type II pyrethroid that is widely used to control harmful insects. The present study was conducted to investigate the possible effects of the sublethal concentration of cypermethrin (0.05 μL/L) on the biometric, hematological, and biochemical parameters of Van fish (Alburnus tarichi Guldenstadt 1814) for 24, 48, 72,...

Lake Van is one of the largest alkaline lakes worldwide and Lake Van Fish (Alburnus tarichi Güldenstädt, 1814) is the only vertebrate species inhabiting it. Lake Van Fish is an anadromous species that migrates to the streams (salinity 0.02%, pH 8.42) flowing into Lake Van (salinity 0.22%, pH 9.8) during the spawning period (April–July). Following s...

Purpose: Ankaferd Blood Stopper® (ABS), a licenced medicinal herbal extract, is commonly used as an effective topical haemostatic agent. This study is designed to investigate whether topical ABS application may cause peripheral nerve degeneration and neuromuscular dysfunction in a mouse sciatic nerve model. Methods: Twenty mice were randomly div...

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, Güldenstadt 1814) were studied. This study was conducted for the first time in Van fish. Which it is very important for...

Van Lake is the largest soda lake in the world. The Van Fish, which is a single fish species has adapted to the extreme conditions of the lake. The fish is anadrom and migrates from the lake to fresh water for reproduction and returns to the lake again. In the present study, the histological structure of the digestive tract of Van Fish in the lake...

Van Lake is the largest soda lake of Turkey and there is only one fish species (Van Fish, Alburnus tarichi Güldenstädt, 1814) that can survive under the extreme conditions of the lake. There are several researches carried out on the issue of lake contamination recently. Gonad abnormalities observed among these fish are one of the most important iss...

The gill histology of the endemic Lake Van Fish (Chalcalburnus tarichi, Pallas 1811) was compared in two different water systems during the reproductive migration from alkaline water to freshwater. The histological examination of gill samples showed that freshwater samples had a thinner primary lamella. While the cells that secrete mucous into the...

Kidneys are important organs that play a role in ion and water regulation in different aquatic environments. The Van fish (Alburnus tarichi, Güldenstädt, 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 fis...

This study focused on hepatosomatic and gonadosomatic index and levels of plasma 17β- estradiol (E2), 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 E2, Vtg and total prote...

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 Çarpanak sites of Van Edremit Gulf (VEG) of lake, between October 2004 and May 2005. The fish living around VEG winters in deep wat...

Recently, an increasing number of studies have shown that Lake Van-the biggest soda lake in the world-is polluted due to an increasing population. Studies have shown abnormalities in the Lake Van fish (Chalcalburnus tarichi), the sole fish species that inhabits the lake. Unlike the vitellogenic and mature oocytes in normal gonads, abnormal gonads s...

Export Date: 18 October 2014

In the present study, we investigated the distribution of 17β-estradiol (E2), 17α-ethynylestradiol (EE2), alkylphenol ethoxylates (APEs) and organochlorine pesticides (DDE/DDT) in water and sediment samples in the Eastern Anatolia of Turkey, Lake Van, which is the largest soda lake in the world. The procedure consisted of solid phase extraction per...

Vitellogenin (Vtg) is an important precursor yolk protein in egg-laying vertebrates, including fish. The 17β-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-deoxy...

Chalcalburnus tarichi is an anadromous cyprinid fish that has adapted to extreme conditions (salinity 22 ‰, pH 9.8 and alkalinity 153 mEq × l(-1)) in Lake Van in eastern Turkey. Changes in immunoreactivity of Na(+)/K(+)-ATPase in gill tissue and osmolarity and ion levels in plasma were investigated in C. tarichi during reproductive migration. Physi...

In this study, the effects of the endocrine-disrupting chemicals known as 17α-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 wer...

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 17alpha,20beta,21-trihydroxyprogesterone (20beta-S), progesterone (P), 17alpha-hydroxyprogesterone (17alpha-HOP), 11-deoxyc...

The gonad histology, gonado-somatic index (GSI), 17β-estradiol (E2) 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 7years old were sampled from November 2003 to February 2004. The ratio of female fish caught in L...