Mert Gürkan

A comparative toxicity study between small and large size zinc oxide nanoparticles in tilapia (Oreochromis niloticus): Organ pathologies, osmoregulatory responses and immunological parameters

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(+)-ATPase activity at all concentrations and increase serum Ca(2+) 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.

Effects of zinc oxide nanoparticles on bioaccumulation and oxidative stress in different organs of tilapia (Oreochromis niloticus)

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 10mg/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.

Effects of Subchronic Exposure to Phosalone on Oxidative Stress and Histopathological Alterations in Common Carp (Cyprinus carpio, L., 1758)

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.

Effects of environmental hypercapnia on hemato-immunological parameters, carbonic anhydrase, and Na+, K+-ATPase enzyme activities in rainbow trout (Oncorhynchus mykiss) tissues

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 4.5 mg L−1 (control) and 14 mg L−1 CO2. No mortalities occurred during the 14 days 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 14 mg 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.

The effects of elevated carbon dioxide and temperature levels on tilapia (Oreochromis mossambicus): Respiratory enzymes, blood pH and hematological parameters

Oreochromis mossambicus were exposed to two different temperature and carbon dioxide partial pressure levels for about two weeks, as the ambient (Control; 25°C, 3.3mg/L CO2), high CO2 (25°C, 14mg/L CO2), high temperature (30°C, 3mg/L CO2) and combined (30°C, 14.1mg/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°C, 14mg/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°C, 14.1mg/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.

Acute Toxic Effects of Cadmium in Larvae of the Green Toad, Pseudepidalea Variabilis (Pallas, 1769) (Amphibia: Anura)

Abstract 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 Lig L-1) for 96 h. The LC10 LC50, and LC90 values of cadmium were calculated to be 26.98, 35.35, and 46.31 Lig L-1, respectively. Our results showed that cadmium had a negative effect on the body size of P. variabilis larvae (over 1 ng L-1). Histological examination detected a fusion of gill lamellae, liver haemorrhage, oedema in the abdominal cavity, and deformations of pronephric tubules (over 10 ng 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.

Effects of subchronic exposure to zinc nanoparticles on tissue accumulation, serum biochemistry, and histopathological changes in tilapia (Oreochromis niloticus)

Zinc nanoparticles (ZnNPs) are among the least investigated NPs and thus their toxicological effects are not known. In this study, tilapia (Oreochromis niloticus) were exposed to 1 and 10 mg/L suspensions of small size (SS, 40–60 nm) and large size (LS, 80–100 nm) ZnNPs for 14 days under semi‐static conditions. Total Zn levels in the intestine, liver, kidney, gill, muscle tissue, and brain were measured. Blood serum glucose (GLU), glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), and lactate dehydrogenase (LDH) were examined to elucidate the physiological disturbances induced by ZnNPs. Organ pathologies were examined for the gills, liver, and kidney to identify injuries associated with exposure. Significant accumulation was observed in the order of intestine, liver, kidney, and gills. Zn levels exhibited time‐ and concentration‐dependent increase in the organs. Accumulation in kidney was also dependent on particle size; NPs SS‐ZnNPs were trapped more effectively than LS‐ZnNPs. No significant accumulation occurred in the brain (p > 0.05) while Zn levels in muscle tissue increased only marginally (p ≥ 0.05). Significant disturbances were noted in serum GOT and LDH (p < 0.05). The GPT levels fluctuated and were not statistically different from those of controls (p > 0.05). Histopathological tubular deformations and mononuclear cell infiltrations were observed in kidney sections. In addition, an increase in melano‐macrophage aggregation intensity was identified on the 7th day in treatments exposed to LS‐ZnNPs. Mononuclear cell infiltrations were identified in liver sections for all treatments. Both ZnNPs caused basal hyperplasia in gill sections. Fusions appeared in the gills after the 7th day in fish treated with 10 mg/L suspensions of SS‐ZnNPs. In addition, separations in the secondary lamella epithelia were observed. The results indicated that exposure to ZnNPs could lead to disturbances in blood biochemistry and cause histopathological injuries in the tissues of O. niloticus.

Acute toxicity of maneb in the tadpoles of common and green toad

Abstract 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. Pesticidi u poljoprivrednoj uporabi mogu biti opasni za vodene organizme, a najugroženiji među vodenim kralježnjacima su vodozemci. Maneb se rabi za suzbijanje gljivičnih bolesti usjeva, voća i povrća. Cilj ovog istraživanja bio je utvrditi akutnu toksičnost maneba u punoglavaca smeđe (Bufo bufo) i zelene krastače (Pseudepidalea viridis). U tu smo svrhu punoglavce u 21. stadiju razvoja izložili manebu (0-5 mg L-1). Po svršetku izloženosti (120 h), LC50 maneba iznosio je 1,966 mg L-1 u B. bufo te 0,332 mg L-1 u P. viridis. Koliko znamo, ove vrijednosti dosada nisu objavljene za ove dvije vrste. Osim letalne koncentracije, pri koncentracijama maneba ≥0.1 mg L-1 za B. bufo odnosno ≥0.05 mg L-1 za P. viridis utvrdili smo i nekrozu jetara, deformacije predbubrežnoga kanalića, propadanje somita te visceralni edem. Naši rezultati pokazuju da su punoglavci smeđe krastače značajno otporniji na maneb od punoglavaca zelene krastače.

A skeletochronological analysis of a population of the Anatolia Newt, Neurergus strauchii (Steindachner, 1887) (Caudata: Salamandridae), in Eastern Anatolia, Turkey

This study presents data on age, growth and longevity of a population of Neurergus strauchii in Eastern Anatolia (Bingöl, Turkey) based on skeletochronological data. The phalangeal diaphyseal cross-sections of 54 individuals studied (12♂, 42♀) 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.