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    A comparative toxicity study between small and large size zinc oxide nanoparticles in tilapia (Oreochromis niloticus): Organ pathologies, osmoregulatory responses and immunological parameters
    (Pergamon-Elsevier Science Ltd, 2016) Kaya, Hasan; Aydin, Fatih; Gurkan, Mert; Yılmaz, Sevdan; Ates, Mehmet; Demir, Veysel; Arslan, Zikri
    Tilapia (Oreochromis niloticus) was exposed to different sizes of zinc oxide nanoparticles (ZnO-NPs) to evaluate their organ pathologies (kidney, liver, gill, and intestine), osmoregulatory responses and immunological parameters. Sub-chronic exposure was conducted in fresh water with 1 and 10 mg/L concentrations of the small (10-30 nm) and large-size ZnO (100 nm) particles for 7 and 14 days. In this study, it is found that small and large forms of ZnO-NPs cause various pathologic findings in the target organs at all concentrations. These findings are increased of melanomacrophage aggregates, tubular deformations, necrosis and cytoplasmic vacuolations in the kidney, oedema, mononuclear cell infiltrations, fatty changes, pyknotic nuclei and hepatocellular vacuolations in the liver, hyperplasia, aneurysms, and epithelial liftings in the gills, and hyperplasia, swelled of goblet cells, villus deformations in the intestine. Results showed that respiratory burst and potential killing activity at the small-size ZnO concentration significantly increased compared to the control group (p < 0.05) but significant reductions of these parameters at the large-size ZnO concentrations compared to control (p < 0.05) were measured. These findings demonstrate the potential of each particle size to cause significant damage to the immune system. Moreover, because ZnO NPs inhibit the Na, K-F-ATPase activity at all concentrations and increase serum Ca2+ and Cl- levels especially in gill, these particles are osmoregulatory and toxicant for tilapia fish. As a summary, both sizes of the particles have led to organ damage, osmoregulatory changes and immune disorder in tilapia fish. (C) 2015 Elsevier Ltd. All rights reserved.
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    A skeletochronological analysis of a population of the Anatolia Newt, Neurergus strauchii (Steindachner, 1887) (Caudata: Salamandridae), in Eastern Anatolia, Turkey
    (Taylor & Francis Ltd, 2015) Yakin, Batuhan Yaman; Cicek, Kerim; Koyun, Mustafa; Gurkan, Mert; Hayretdag, Sibel; Tok, Cemal Varol
    This study presents data on age, growth and longevity of a population of Neurergus strauchii in Eastern Anatolia (Bingol, Turkey) based on skeletochronological data. The phalangeal diaphyseal cross-sections of 54 individuals studied (12o, 42f) showed that females are on average older than males: the ages ranged from 6 to 14 years, with an average age of 8.8 years in males and 10.9 years in females. Sexual maturity is reached at an age of 4-5 years in both sexes. The slow growth and the longevity make the species vulnerable.
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    Acute toxic effects of cadmium in larvae of the green toad, Pseudepidalea variabilis (Pallas, 1769) (Amphibia: Anura)
    (Inst Medical Research & Occupational Health, 2014) Gurkan, Mert; Cetin, Ayse; Hayretdag, Sibel
    The environmental impact of cadmium use and its accumulation in nature have increased to alarming levels. This study aimed to morphologically and histologically investigate the acute toxic effects of cadmium on green toad, Pseudepidalea variabilis (Pallas, 1769) larvae. Embryos were obtained from specimens collected in amplexus from nature and kept under laboratory conditions until stage 26, when they were exposed to cadmium (0, 1, 5, 10, 25, and 50 mu g L-1) for 96 h. The LC10, LC50, and LC90 values of cadmium were calculated to be 26.98, 35.35, and 46.31 mu g L-1, respectively. Our results showed that cadmium had a negative effect on the body size of P. variabilis larvae (over 1 mu g L-1). Histological examination detected a fusion of gill lamellae, liver haemorrhage, oedema in the abdominal cavity, and deformations of pronephric tubules (over 10 mu g L-1). Our findings suggest that the green toad was sensitive to the cadmium treatment, with LC50 values lower than those reported by other studies. Thus, this species could be considered a reliable indicator species of environmental stress in aquatic ecosystem.
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    Acute toxicity of maneb in the tadpoles of common and green toad
    (Inst Medical Research & Occupational Health, 2015) Gurkan, Mert; Hayretdag, Sibel
    Pesticides used in agriculture can have hazardous effects on aquatic organisms, and amphibians are even more threatened than other aquatic vertebrates. Maneb is widely used to control fungal diseases on crops, fruits, and vegetables. The aim of this study was to investigate the acute toxic effects of maneb on the common (Bufo bufo) and green toad (Pseudepidalea viridis) tadpoles. Tadpoles at the development stage 21 were exposed to maneb (0-5 mg L-1) for 120 h. Maneb LC50 values at hour 120 were 1.966 mg L-1 for B. bufo and 0.332 mg L-1 for P. viridis. To the best of our knowledge, these are the first published LC50 findings for the two species. Visceral oedema and tail deformations were observed in both species. We also observed liver necrosis, pronephric tubule deformations, somite deteriorations, and visceral oedema at maneb concentrations >= 0.1 mg L-1 for B. bufo and >= 0.05 mg L-1 for P. viridis. Our results show that B. bufo tadpoles have a much higher resilience to maneb than P. viridis tadpoles. This resilience seems to be related to the larger size of the B. bufo tadpoles and their ability to metamorphose faster in adverse conditions. Future research should look into the mechanisms of toxic action of maneb in anurans.
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    Effects of dietary protein level on growth, histology and digestive enzyme activities of ornamental fish Ancistrus cirrhosus
    (Wiley, 2022) Sahin, Tolga; Gurkan, Mert
    Regardless of the developmental stage of the cultured organism, proper nutritional care is essential. A significant number of aquacultural species rely on protein as their main energy source and protein feeds sold in the ornamental market are formulated with widely varying protein inclusion levels. As Ancistrus cirrhosus is one of the most popular ornamental fish species, this study aimed to determine the effects of different protein levels on growth, digestive enzyme activities and liver and intestinal histopathology. Therefore, 450 fry (98.5 +/- 3.1 mg [mean +/- SE]), 5-6 weeks old, were fed six different experimental diets containing 30%, 35%, 40%, 45%, 50% and 55% crude protein in triplicate groups for 60 days. The results demonstrated that no significant differences were observed in the final lengths, whole-body protein levels, body condition indices and lipase and alkaline phosphatase activities of fish between groups. The fish fed with a 40% protein diet differed positively from other experimental groups in terms of final weight, FCR, SGR, proteolytic enzyme activities and histopathological findings. Lower proteolytic activity was ascertained in fish fed feed containing lower levels of protein (30%, 35%) and increased histopathological defects in the intestine and liver of fish fed feed containing over 40% protein (45%, 50% and 55%). Based on our results, a diet with a 40% protein level is most beneficial for the rearing of A. cirrhosus fry. Further research is required to determine optimal ratios, which are predicted to be between 35 and 40.
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    Effects of environmental hypercapnia on hemato-immunological parameters, carbonic anhydrase, and Na+, K+-ATPase enzyme activities in rainbow trout Oncorhynchus mykiss) tissues
    (Taylor & Francis Ltd, 2013) Kaya, Hasan; Yılmaz, Sevdan; Gurkan, Mert; Hisar, Olcay
    In this study, the effects of environmental hypercapnia on hemato-immunological parameters and the activities of respiratory enzymes such as carbonic anhydrase (CA) and Na+, K+-ATPase were investigated in rainbow trout (Oncorhynchus mykiss) tissues (gill, liver and kidney). Batches of 12 fish were exposed to 4.5mg L-1 (control) and 14mg L-1 CO2. No mortalities occurred during the 14days of the experimental period. Red blood cell (RBC), hemoglobin (Hb), and hematocrit (Ht) levels, and innate immune parameters such as nitro blue tetrazolium (NBT), lysozyme, and myeloperoxidase activities, and the melano-macrophage frequency were negatively affected by elevated CO2 levels. Patterns of change in CA activity differed among the gill, liver, and kidney. Compared with the activities of CA in the control group, the CA enzyme was significantly stimulated at day 7 in the gill tissue, whereas it was stimulated at day 14 of the experiment in the liver tissue of fish exposed to 14mg L-1 CO2 (P < 0.05). In contrast to the pattern of CA enzyme activities, the Na+, K+-ATPase enzymes were stimulated significantly in the liver after day 7 but inhibited in the kidney and gill (P < 0.05). These results suggest that a subchronic exposure to hypercapnia of rainbow trout tissues may lead to adaptive changes in the respiratory enzymes and negatively affects hemato-immunological parameters.
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    EFFECTS OF SUBCHRONIC EXPOSURE TO PHOSALONE ON OXIDATIVE STRESS AND HISTOPATHOLOGICAL ALTERATIONS IN COMMON CARP (Cyprinus carpio, L., 1758)
    (Taylor & Francis Inc, 2013) Kaya, Hasan; Celik, Ekrem Sanver; Gurkan, Mert; Yılmaz, Sevdan; Akbulut, Mehmet
    In this study, possible oxidative stress, biomarkers, and histopathological alterations were investigated in common carp (Cyprinus carpio, L., 1758) that were exposed to various phosalone concentrations in vivo. Fish were exposed to 0.15, 0.3, and 0.6 mg/L phosalone concentrations in a semistatic regime for 14 d. Biomarkers, including Na+, K+-ATPase, reduced glutathione (GSH), thiobarbituric acid-reactive substances (TBARS), and histopathological changes, were determined in gills, liver, and kidney tissues of fish. Sublethal phosalone concentrations produced lipid peroxidation and impairment in the antioxidant defense system by increasing reactive oxygen species (ROS) production. While GSH increased in all groups at d 7 compared to control, GSH fell significantly at medium and high doses at d 14. Reduced GSH levels were diminished in all tissues and a significant induction in lipid peroxidation (TBARS) was observed. Na+,K+-ATPase enzyme activity was significantly inhibited especially in gills. No histopathological effects were observed in the control group. Lamellar aneurysm, lamellar fusion, hyperplasia, epithelial lifting, and hemorrhages were observed in gill tissues exposed to phosalone. Histopathological effects in the liver tissues of fish exposed to phosalone were characterized by cytoplasmic vacuolation, congestion, hypertrophy, and nuclear degeneration. Hypertrophy, tubule degeneration, mononuclear cell infiltration, and dilation of glomerular capillaries were noted in kidney tissues exposed to phosalone. The results indicate that phosalone exposure adversely affected the health of the fish, attributable to oxidative stress.
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    Effects of three different nanoparticles on bioaccumulation, oxidative stress, osmoregulatory, and immune responses of Carcinus aestuarii
    (Taylor & Francis Ltd, 2018) Gurkan, Mert
    In this study, the toxicity of CuO (40 nm), alpha-Al2O3 (40 nm), and alpha-Fe2O3 (20-40 nm) nanoparticles was comparatively investigated on Carcinus aestuarii. Crabs were semi-statically exposed to 1mg/L of each for 14 days and their accumulation and distribution in tissue and hemolymph, potential oxidative stress mechanism, total hemocyte counts and types, and the osmoregulatory and ionoregulatory responses were determined. The tissue distribution of CuO nanoparticles was hepatopancreas > hemolymph >= gill > muscle, for alpha-Fe2O3 gill > hepatopancreas > muscle > hemolymph, and for alpha-Al2O3 gill > muscle >= hemolymph > hepatopancreas. While alpha-Al2O3 and alpha-Fe2O3 NPs, induced lipid peroxidation and changes in antioxidant enzyme activity in the hepatopancreas tissue, the oxidative damage caused by the CuO nanoparticles was minimal. All three nanoparticles, copper in particular, elicit osmoregulatory and ionoregulatory toxicity at this concentration, due to the inhibition of Na+, K+-ATPase activity in the gill and depletion of hemolymph and carcass ion concentrations.
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    Effects of zinc oxide nanoparticles on bioaccumulation and oxidative stress in different organs of tilapia (Oreochromis niloticus)
    (Elsevier Science Bv, 2015) Kaya, Hasan; Aydin, Fatih; Gurkan, Mert; Yılmaz, Sevdan; Ates, Mehmet; Demir, Veysel; Arslan, Zikri
    Nano-size zinc oxide particles (ZnO NPs) are used in diverse industrial and commercial fields. However, the information from existing studies is not sufficient in evaluating the potential toxic effects of ZnO NPs. In this study, tilapia fish (Oreochromis niloticus) were exposed to different concentrations of small and large ZnO NPs in vivo. Accumulation in various organs/tissues (liver, gill, intestine, kidney, brain and muscle) and possible oxidative stress mechanisms were investigated comparatively. Fish were exposed to 1 and 10 mg/L concentrations of small (10-30 nm) and large (100 nm) ZnO NPs semi-statically for 14 days. Both small and large ZnO NPs accumulated substantially in the tissues. Accumulation for the small ZnO NPs was significantly higher compared to larger NPs under same exposure regimes. Significant fluctuations were observed in antioxidant defense system biomarkers, including Superoxide dismutase (SOD), Catalase (CAT) and Glutathione (GSH) levels depending on particle size, exposure time and concentration. Lipid peroxidation measured with TBARS levels were higher in groups exposed to the suspensions of small ZnO NPs than that of large ZnO NPs and controls. These results imply that colloidal suspensions of small ZnO NPs induce elevated oxidative stress and toxic effects on tilapia compared to the larger NPs. (C) 2015 Elsevier B.V. All rights reserved.
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    Embryonic and larval development of black skirt tetra (Gymnocorymbus ternetzi, Boulenger, 1895) under laboratory conditions
    (Wiley, 2012) Celik, Ihsan; Celik, Pinar; Cirik, Sukran; Gurkan, Mert; Hayretdag, Sibel
    The embryonic and larval development of black skirt tetra, Gymnocorymbus ternetzi, are described under controlled laboratory conditions. In addition, major histomorphological changes and the allometric growth patterns during larval development have been described. The laboratory-reared broodstock, that is 1 similar to year of age, were spawned. Hatching occurred 2021 similar to h after spawning at 24 +/- 0.5 degrees C. The cleavage was finished in 2 similar to h and the early blastula stage occurred at 2:04 hours after spawning. The gastrulation started at 3:20 similar to hours and 30% epiboly was observed at 3:34 similar to hours after spawning. Eight-somite stage was observed at 08:33 hours. And embryonic developmental stage was completed at 21 similar to h after spawning. The newly hatched larvae were 1442 +/- 14.3 similar to mu m in mean total length (TL). The mouth opened at 3 days after hatching (DAH). The yolk sac had been totally absorbed and the larvae started to swim actively within 34 similar to days. Notochord flexion began at 11 DAH. The metamorphosis was completed and the larvae transformed into juveniles at 32 DAH. In this paper, the full developmental sequence from egg to juvenile of G. ternetzi is described for the first time.
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    Evaluation of Possible Toxic Effects of Boric Acid in Palourde Clam (Ruditapes decussatus) Through Histological Changes and Oxidative Responses
    (Springernature, 2024) Gurkan, Selin Erturk; Gurkan, Mert; Saritunc, Volkan; Ibis, Ezgi Can; Gunes, Berkay
    The extensive utilization of boric acid, particularly in industrial and agricultural sectors, also engenders concerns regarding the toxicity of boron and its derivatives. Particularly, the behavior of boric acid at increasing concentrations in aquatic ecosystems remains poorly understood. In light of these concerns, this study aimed to investigate the toxicity of boric acid in bivalves, which occupy a critical position in the food chain. Specimens of Ruditapes decussatus, which had not been previously exposed to any pollutants and were cultivated under controlled conditions, were subjected to three different concentrations of boric acid (0.05 mg/L, 0.5 mg/L, and 5 mg/L) in vitro for 96 h. Following the exposure period, the specimens were assessed for histological changes (the mantle, gill, and digestive gland) and specific oxidative parameters (the gill and digestive gland), including superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferase, and lipid peroxidation (LPO). The research findings indicated that boric acid primarily induced oxidative damage at the applied concentrations and increased antioxidant levels (p < 0.05). Moreover, although no significant histopathological abnormalities were observed in the examined histological sections, subtle changes were noted. This study evaluated the potential adverse effects of boric acid on bivalves, which are crucial components of the aquatic food chain, utilizing histological and specific physiological parameters following its introduction into aquatic environments. It is anticipated that the findings of this study will contribute to the development of new insights and perspectives regarding the extensive use of boric acid.
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    Evaluation of the health of Mediterranean mussels ( Mytilus galloprovincialis Lamarck, 1819) distributed in the Çanakkale strait, Turkey
    (Elsevier Sci Ltd, 2024) Gurkan, Mert; Gurkan, Selin Erturk; Kunili, Ibrahim Ender; Acar, Secil; Ozel, Osman Tolga; Duzgunes, Zehra Duygu; Ture, Mustafa
    The observation of mortality in Mediterranean mussels ( Mytilus galloprovincialis ) distributed in the & Ccedil;anakkale Strait in recent years was influential in developing the research question for this study. In this study, the presence of bacteria ( Vibrio spp.) and parasites ( Marteilia spp. and Haplosporidium spp.) in mussels collected from Kumkale, Kepez, and Umurbey stations in the & Ccedil;anakkale Strait was investigated seasonally. Microbiological findings, histopathology, oxidative stress enzymes and their gene expressions, lipid peroxidation, lysosomal membrane stability, and changes in haemolymph were examined. In summer samples, both the defence system and the extent of damage were higher in gill tissue. In winter samples, enzyme activities and lipid peroxidation were found to be predominantly higher in digestive gland tissues. Histological examinations and Hemacolor staining revealed the presence of protozoan cysts, and for bacterial examination, molecular analysis performed after culturing revealed the presence of 7 Vibrio species. While the total numbers of heterotrophic bacteria detected in all samples were at acceptable levels, the predominance of Vibrio spp. numbers among the total heterotrophic bacteria detected in almost all samples were noteworthy. The total hemocyte count was calculated as 5.810(4) +/- 0.58 (cells/mm 3 ) in winter and 7.210(4) +/- 1.03 (cells/mm 3 ) in summer. These factors are considered to be possible causes of mussel mortality.
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    Histopathology and Blood Parameters of Bogue Fish (Boops boops, Linnaeus 1758) Parasitized by Ceratothoa oestroides (Isopoda:Cymothoidae)
    (Central Fisheries Research Inst, 2016) Ozdemir, Gulbahar; Celik, Ekrem Sanver; Yılmaz, Sevdan; Gurkan, Mert; Kaya, Hasan
    Bogue fish (B. boops, Linnaeus 1758) were captured using a seine net in the Lagoon of Lapseki, located in the Dardanelles, Turkey. We examined a total of 200 fish and assessed the hematological, biochemical, immunological parameters and histopathology of the buccal cavity of them (40 of them not parasitized, 40 of them parasitized). No significant difference was found between parasitized and not parasitized fish groups in terms of the average biometric indices, body weight and length values. Blood leucocytes counts, haemoglobin and hematocrit values, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, glucose, triglyceride, total protein, globulin, aspartate aminotransferase, NBT and lysozyme activity significantly reduced and bilirubin, alkaline phosphatase, creatine kinase, lactate dehydrogenase and myeloperoxidase activity significantly increased in C. oestroides parasitized fish compared to not parasitized ones. Infestation by this parasite resulted in histopathological manifestations such as hemorrhage, edema, necrosis, deformation in striated muscle cells, hypertrophy in chondrocytes and epithelial cells, mononuclear cell infiltration. According to the results obtained in the present study, it can be suggested that blood and histopathological variations influenced by parasites in the bogue fish can cause the fish to be more susceptible to pollutants, predators and diseases.
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    Immunological Responses, Expression of Immune-Related Genes, and Disease Resistance of Rainbow Trout (Oncorhynchus mykiss) Fed Diets Supplied with Capsicum (Capsicum annuum) Oleoresin
    (Mdpi, 2024) Yılmaz, Sevdan; Kenanoglu, Osman Nezih; Ergün, Sebahattin; Celik, Ekrem Sanver; Gurkan, Mert; Mehana, Elsayed Eldeeb; Abdel-Latif, Hany M. R.
    A 45-day feeding study was carried out to assess the immune-stimulatory effects of capsicum oleoresin when added to rainbow trout diets. A total of 450 fish (mean weight: 155.20 +/- 1.96 g) were distributed into 400 L tanks (30 fish/tank) across five experimental groups: control (CT, 0%), C7 (0.7%), C14 (1.4%), C21 (2.1%), and C28 (2.8%). Each group consisted of three replicate tanks. At the end of this period, hemato-biochemical parameters, innate immune responses, and immune-related gene expression levels were evaluated, and a histological examination of head kidney and liver sections was conducted. Finally, fish in all groups were challenged with Lactococcus garvieae and observed for an additional 20 days. The results revealed that oleoresin supplementation enhanced the immune responses of the treated fish, which was evidenced by the increased globulin, total protein, respiratory burst activity, and total immunoglobulin levels. The highest expression levels of the il-8, il-1 beta, TGF-beta, and SAA genes was noticed in the C7 group, as compared with the results for the other groups. The IgT gene expression levels were higher in all experimental groups than in the CT group, and this increase was at the highest level in the C28 group. Following the bacterial challenge, all experimental groups displayed higher survival rates compared to that of the CT group. These values were 75.93, 72.22, 46.30, 33.33, and 29.63% in the C7, C14, C21, C28, and CT groups, respectively, with the C7 group displaying the highest survival rate among the groups. The histological examination of liver and head kidney tissues revealed that higher doses (in the C21 and C28 groups) showed an increase in cytoplasmic vacuolization, which causes adverse effects on fish health. However, the C7 group displayed normal histological structure in both tissues. Taken together, the most favorable immune responses were achieved in the C7 group, suggesting that 0.7% oleoresin could be applied to rainbow trout to boost immunity and protect the fish from diseases.
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    Larval Development of The Freshwater Angelfish Pterophyllum scalare (Teleostei: Cichlidae)
    (Central Fisheries Research Inst, 2014) Celik, Ihsan; Celik, Pinar; Gurkan, Mert; Sahin, Tolga
    In this study, the larval development of freshwater angelfish, Pterophyllum scalare, was described under controlled aquarium conditions. Major histomorphological changes and the allometric growth patterns during the larval development have been described. The larvae were obtained from three pairs of freshwater angelfish, which were maintained in glass tanks. The larvae were sampled for measurement and photography. They were observed under a stereomicroscope, photographed using a photomicrographic system. The larval development of angelfish were described from 1 days after hatching (DAH) to 24 DAH. Embryonic developmental stage was completed at day 3 after spawning at 24 +/- 1 degrees C. The newly hatched larvae had 4.24 +/- 0.28 mm total length (TL). The mouth opened at 3 DAH. The larvae started to swim actively within the next 3-4 days. Notochord flexion began at 3-4 DAH. The yolk sac has been totally absorbed at 6 DAH. The metamorphosis was completed and the larvae transformed into juveniles at 23-24 DAH.
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    Mass mortality in endangered fan mussels Pinna nobilis (Linnaeus 1758) caused by co-infection of Haplosporidium pinnae and multiple Vibrio infection in canakkale Strait, Turkey
    (Taylor and Francis, 2021) Kunili, Ibrahim Ender; Erturk Gurkan, Selin; Aksu, Ata; Turgay, Emre; Cakir, Fikret; Gurkan, Mert; Altinagac, Ugur
    Purpose: Pinna nobilis (fan mussel) is one of the most important endemic bivalve molluscs in the Mediterranean and mass mortality events were observed in these mussels in recent years. In this study, we report mass mortalities caused by Haplosporidium pinnae, which has been spreading in the Mediterranean for 3 years, and reached the C¸anakkale Strait, which is the entrance of the Marmara and the Black Sea. Material and methods: Field observations during sampling and subsequent histopathological, biochemical, genetic, and microbiological analyses were carried out. Results: These analyses showed that H. pinnae infection spread among the natural beds of P. nobilis, causing severe tissue damage and oxidative stress. Our phylogenetic analyses suggested that the parasite spread through the Mediterranean much faster than thought. The results showed that vibriosis originating from Vibrio coralliilyticus, Vibrio tubiashii, Vibrio mediterranei, and Vibrio hispanicus, acted together with H. pinnae in infected individuals and caused death. Conclusion: It is highly probable that the spread of H. pinnae to the Sea of Marmara and the Black Sea may occur earlier than expected, and it was concluded that mass deaths were caused by co-infection with H. pinnae and a geographically specific marine pathogen that can infect P. nobilis populations.
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    Morphological and histological effects of copper sulfate on the larval development of green toad, Bufo viridis
    (Tubitak Scientific & Technological Research Council Turkey, 2012) Gurkan, Mert; Hayretdag, Sibel
    Declines in populations of amphibians have been occurring more dramatically over the past 25 years. The declines have various causes. One of the possible causes of amphibian declines is pesticides. Copper sulfate is commonly used as a fungicide in vineyards and gardens in Turkey. In this study, our purpose was to explain the morphologically and histologically acute toxic effects of copper sulfate on Bufo viridis tadpoles. B. viridis tadpoles at Gosner stage 21 were exposed to different concentrations (0.01, 0.05, and 0.1 mg/L) of copper sulfate for 120 h. The LC50 value of copper sulfate was calculated as 0.058 mg/L. Morphological measurements indicated that copper sulfate concentrations of 0.05 and 0.1 mg/L caused poor larval development and growth. Edema was observed in the histological sections, especially on the cross-sections passing from the head (>= 0.01 mg/L CuSO4). Furthermore, hepatocellular degeneration in the liver, deformation of gastrointestinal epithelial cells, and deformation and anomalies in somite formations were all observed (>= 0.01 mg/L CuSO4). Reduced reaction to stimuli, loss of equilibrium, and shortening of swimming distance were observed in the tadpoles of the 0.05 and 0.1 mg/L CuSO4 treatment groups.
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    Pathological and oxidative stress responses of Mytilus galloprovincialis to Vibrio mediterranei infection: An in vivo challenge
    (Academic Press Ltd- Elsevier Science Ltd, 2024) Ter, Ummugulsum; Gurkan, Selin Erturk; Gurkan, Mert; Kunili, Ibrahim Ender; Aksoy, Emircan
    Since the identification of Vibrio mediterranei as a causative agent in mass mortalities of pen shells across the Mediterranean, elucidating its pathogenicity, virulence, and interactions with other bivalves has gained importance. While the cellular and immune responses of bivalves to various Vibrio species have been extensively studied, the infectious characteristics of this Vibrio species, particularly in the context of pen shell outbreaks, remain unclear for other bivalves. Therefore, to evaluate its pathogenicity, we investigated the histological and oxidative effects on the Mediterranean mussel (Mytilus galloprovincialis), a key species in aquaculture. Two distinct infection setups were established: one involving the inoculation of seawater with the bacterial isolate and another involving direct injection of the bacteria into the mussels. After a 24-h exposure period, histological evaluations were conducted on the mantle, gill, and digestive gland tissues of the mussels. Additionally, measurements of superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferase (GST), and lipid peroxidation levels were performed in the gill and digestive gland tissues. Oxidative responses were significantly elevated in both infection setups compared to the control group, with the directly injected samples exhibiting the highest oxidative responses (p < 0.05). Histological findings indicated that tissue-specific responses to host-pathogen interactions were consistent under both infection conditions. Notable observations included intense hemocytic infiltration in tissues, epithelial hyperplasia, and vacuolization in the gills, as well as focal necrotic areas in the digestive gland. The findings of this study indicate that V. mediterranei, a relatively novel pathogen, can provoke significant acute immune responses and tissue-level reactions in M. galloprovincialis, a species that is both widely distributed and vital to the food chain. These insights into the potential susceptibility of mussels underscore the need for further comprehensive research and inform the development of effective management strategies.
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    The effects of Capsicum annuum oleoresin, as a dietary carotenoid, on growth, gut microbiome, intestinal histomorphometry, and sensory characteristics of Oncorhynchus mykiss
    (Wiley, 2024) Yılmaz, Sevdan; Celik, Ekrem Sanver; Ergün, Sebahattin; Gurkan, Mert; Kesbic, Fevziye Isil; Abdel-Latif, Hany M. R.
    This study was designed to explore the dietary effects of Capsicum annuum oleoresin (CAO) on growth, body composition, sensory characteristics, gut microbiome, and intestinal histomorphometry of rainbow trout. Fish (195.13 +/- 1.55 g) were fed diets with various CAO levels (0.0-Control, 7.0- g kg (-1) C7, 14.0 g kg (-1) -C14, 21.0 g kg (-1)-C21, and 28.0 g kg (-1)-C28) for a 30-day period. Results revealed that the maximum growth was achieved in C7 and C14 groups. Nevertheless, the growth parameters were similar in other groups compared to the control. Moreover, there were significant increases in dry matter and crude lipid contents in all CAO groups compared with the controls. The mean abundances (%) of the prevalent bacteria at the genus level in the intestinal trout samples presented no significant changes among the test groups. Dietary CAO significantly changed the intestinal histological structure, and was manifested by an increased number of goblet cells in the CAO-supplied groups. However, there were intestinal villus epithelial deformations associated with increasing dietary CAO, and were most prominent in the C28 group. The sensory attributes of cooked trout fillets showed that capsicum's pungent odor and taste was evident in the C14 group and subsequently increased with increasing dietary CAO levels. Accordingly, the results showed, for the first time, that dietary CAO at levels (7-14 g kg(-1)) can enhance the growth of rainbow trout without negative effects on the sensory characters and gut health.
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    The effects of elevated carbon dioxide and temperature levels on tilapia (Oreochromis mossambicus): Respiratory enzymes, blood pH and hematological parameters
    (Elsevier Science Bv, 2016) Kaya, Hasan; Hisar, Olcay; Yılmaz, Sevdan; Gurkan, Mert; Hisar, Sukriye Aras
    Oreochromis mossambicus were exposed to two different temperature and carbon dioxide partial pressure levels for about two weeks, as the ambient (Control; 25 degrees C, 3.3 mg/L CO2), high CO2 (25 degrees C, 14 mg/L CO2), high temperature (30 degrees C, 3 mg/L CO2) and combined (30 degrees C, 14.1 mg/L CO2) groups. No mortality was observed during the experiments. As a result of the study, elevated CO2 concentrations cause negative effects on the hematological parameters. At the end of the study, while the blood Carbonic Anhydrase (CA) activity, in the high CO2 group (25 degrees C, 14 mg/L CO2), statistically increased at the 7th day compared to the control group, it decreased at the 14th day (p<0.05). In addition, the blood CA activity, in the combined (30 degrees C, 14.1 mg/L CO2) group, showed a decrease at the 14th day compared to the control group (p<0.05). At the end of study, unlike the blood CA activity, gill, liver and kidney CA activity showed an increase in the tissues compared to the control groups (p<0.05). Furthermore, the Na+, K+-ATPase activities were stimulated significantly in the gills in both high CO2 and temperature groups at day 7, but it showed a significant amount of inhibition at the 14th day compared to the control groups. Overall, increasing carbon dioxide concentration in different temperatures has negative effects on the hematological parameters and respiratory enzyme of the tilapia fish. In addition, it is observed that the fish survive at negative conditions with adaptation mechanisms. (C) 2016 Elsevier B.V. All rights reserved.