Onder Aksu | Munzur University (original) (raw)

Papers by Onder Aksu

Bulletin of Environmental Contamination and Toxicology, 2020

Quantum dots (QDs), such as cadmium selenide (CdSe) and lead selenide (PbSe) exhibit excellent op... more Quantum dots (QDs), such as cadmium selenide (CdSe) and lead selenide (PbSe) exhibit excellent optical, magnetic and chemical properties due to their extremely size (ca. 1-10 nm) and are attractive semiconductor nanomaterials for optical studies and energy storage. In this study, aqueous synthesis of CdSe and PbSe QDs in a size range of 2-10 nm was described. Synthesized QDs were characterized using SEM and TEM, DLS, zeta potential, FTIR, EDX and XRD. Highest accumulation (72.5 ± 5.8 mg L −1) of PbSe QDs occurred at 10 ppm suspensions. In general accumulation increased up to 48 h exposure then fluctuate tended to decline. For CdSe QDs, accumulation tended to decrease for 72 h exposure except that for 5 ppm groups. For the elimination period, in general, the elimination levels of PbSe and CdSe QDs from exposed individuals decreased (p < 0.05) even it has some fluctuate.

Bulletin of Environmental Contamination and Toxicology, 2019

In this study, the effect of zinc nanoparticles (Zn NPs) and zinc oxide nanoparticles (ZnO NPs) o... more In this study, the effect of zinc nanoparticles (Zn NPs) and zinc oxide nanoparticles (ZnO NPs) on Artemia salina and Daphnia magna, the primary consumer organisms were investigated. In this sense, investigation of trophic transfer and ecological sustainability potentials among living things, such as fish and crustaceans that are at the top of the food chain were also aimed. Zn NPs in the size of 40-60 nm and 80-100 nm and ZnO NPs (10-30 nm) were administered to A. salina and D. manga (respectively in total 105000 and 14000 individuals) in seven groups (Control, 0.2, 1, 5, 10, 25 ve 50 ppm) with three repetitions for a period of 72 h. Intensive and possible misuse of nanoscale materials is one of the biggest threats to the environment and all living things worldwide. Therefore, the control mechanisms for the use of NPs need to be established.

Science of The Total Environment, 2019

In the study, Zn in the size of 40-60 nm and 80-100 nm and ZnO in the size of 10-30 nm were appli... more In the study, Zn in the size of 40-60 nm and 80-100 nm and ZnO in the size of 10-30 nm were applied to A. salina and D. magna individuals in 7 groups with 3 repetitions. Measurements were made at 24th, 48th and 72nd hours and elimination values were examined at +24 h. LC50 values of NPs were determined and chemical analysis (metal accumulation and elimination), ion quantities which were given to the environment and the survival rates of organisms were determined after the exposure. According to the results of phase contrast microscopy, it was found that both experimental organisms absorbed the NPs in the medium level. In the toxicity results of D. magna, it can be said that Zn NP (40-60 nm) has a highly toxic effect only at 50 ppm concentration for 48 h and lethal dose can be accepted as of 5 ppm at the end of 72 h. In A. salina individuals, it is clearly seen that there is an increase in mortality in organisms parallel to the dose increase. Although all NPs were applied to organisms in low doses corresponding to environmental values, it was observed that toxic effect was in parallel with the increase in time. It is clearly known that there is the inverse proportion between the size of NPs and the toxic effect. The smaller the size of NPs is, the higher the toxic effect becomes When the results of Zn accumulation and elimination of A. salina and D. magna individuals exposed to the Zn and ZnO NPs were examined; it was found that accumulation and elimination occurred in parallel with the increase in concentration at each application hour and elimination. Intensive and possible misuse of nanoscale materials is one of the biggest threats to the environment and all living things worldwide.

Environmental Toxicology, 2019

In this study, the impact of alpha-iron oxide (α-Fe 2 O 3 , 20-40 nm) and gamma iron oxide (γ-Fe ... more In this study, the impact of alpha-iron oxide (α-Fe 2 O 3 , 20-40 nm) and gamma iron oxide (γ-Fe 2 O 3 , 20-40 nm) nanoparticles (NPs) on phytoplankton species Selenastrum capricornutum and Nannochloropsis oculata was investigated Characterizations of the NPs were systematically carried out by TEM, dynamic light scattering, zeta potential, X-ray diffraction, SEM, and Fourier transformation infrared spectroscopy. Acute toxicity was tested between 0.2 and 50 mg/L for each NP for a period of 72 hours exposure. γ-Fe 2 O 3 NP inhibited development of N oculata at the rate of 54% in 0.2 mg/L group with a high mortality rate of up to 82%. α-Fe 2 O 3 NPs were less toxic that induced 97% mortality on N oculata at 10 mg/L suspensions. In contrast, α-Fe 2 O 3 NP inhibited growth of S capricornutum strongly (73%) in 0.2 mg/L group. γ-Fe 2 O 3 NPs showed similar growth inhibition (72%) on S capricornutum in 10 mg/L suspensions. Despite the differential effects, the results indicated acute toxicity of α-Fe 2 O 3 and γ-Fe 2 O 3 NPs on N oculata and S capricornutum.

Cellular and Molecular Biology, 2018

In this study, the effects of some plant hydrosols (distilled plant waters) based upon some hemat... more In this study, the effects of some plant hydrosols (distilled plant waters) based upon some hematological parameters and Nitroblue Tetrazolium (NBT) activities in the common carp (Cyprinus carpio Linnaeus, 1758) infected with Yersinia ruckeri were investigated. In the trial, it was utilized totally 200 common carps with 54.3±6.7 g mean live weight and 15.7±1.8 cm mean total lenght. The 10% rate of the common yarrow (Achillea millefolium Linnaeus) hydrosol; 0.5% rate of the cinnamon (Cinnamomum zeylanicum Blume) hydrosol; and 5% rate of the rosemary (Rosemarinus officinalis Linnaeus) hydrosol were applied to fish as a bath treatment. The erythrocyte (RBC), leukocyte count (WBC), hematocrit value (HCT), haemoglobin amount (Hg), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), and activities of NBT in the blood samples taken from the caudal vena of the control and experimental fish groups were analyzed in the 7th, 14t...

Crustaceana, 2017

In this study, we determined the effects of the textile dyes Remazol Brillant Blue R (RBBR) and C... more In this study, we determined the effects of the textile dyes Remazol Brillant Blue R (RBBR) and Congo Red (CR) on the enzymatic activities of Glutathione S-Transferase (GST), cytochrome P450 (CYP1A1) and Lactate dehydrogenase (LDH), in hepatopancreas of Astacus leptodactylus. The crayfishes were exposed to 0.5, 1.0, and 2.0 mg/l of RBBR or CR, for 24 and 48 h. The recorded GST activity clearly increased after 24 or 48 h exposure to CR, compared to a control group (), but the changes of GST activity depending on time and dose were not statistically significant in the RRBR group (). The activity of CYP1A1 generally decreased, but LDH activity increased in the groups exposed to different doses of CR and RBBR, when compared to their control groups. Detoxification enzymes (as GST, and CYP1A1) and metabolic enzymes (as LDH) can be proven to make useful markers for further evaluating the physiological effects of CR and RBBR on crayfish.

Fresenius Environmental Bulletin, 2012

Fresenius Environmental Bulletin

Dünyada olduğu gibi ülkemizde artan taleplere paralel olarak artan enerji ihtiyacı ile yenilenebi... more Dünyada olduğu gibi ülkemizde artan taleplere paralel olarak artan enerji ihtiyacı ile yenilenebilir, ucuz ve nispeten çevre kirliliğine sebep olmayan hidroelektrik santrallerinin (HES) önemi artmıştır. Hidroelektrik santrallerin su kullanımı sonucunda, akarsuların bir bölümü doğal yatağından uzaklaştırılmaktadır. Akarsu yatağına bir miktar su bırakılmaktadır. Bırakılan bu su mevsimlere bağlı olarak yıl içerisinde önemli değişimler gösterebilmektedir. Ancak, bu sistemlerin ekolojik denge üzerinde olumlu ve olumsuz etkileri vardır. Bu dengede önemli bir yeri olan balık ve diğer sucul canlılar yerli, insan ise o habitatta istilacı konumdadır. Balıklar, varlığını koruyabilmek için belirli zamanlarda kısa ya da uzun olan beslenme ve üreme göçünü yapabilmesi zorunluluktur. Bu göçler yeterli miktarda suyun dere yatağından akması ve balık geçitlerinin doğru şekilde planlanması ile mümkün olabilir. HES’lerde yapılması planlanan balık geçidinde, basamakların orta kısımda ve su kanal içerisin...

kaynaktır. Türkiye, dünyanın en hızlı akan nehirlerinden bir kaçına sahip olmasına rağmen su reze... more kaynaktır. Türkiye, dünyanın en hızlı akan nehirlerinden bir kaçına sahip olmasına rağmen su rezervleri bakımından alt sıralarda yer almaktadır ve yaklaşık 200 milyar m3 su miktarına sahiptir. Dağ alabalığı olarak bilinen Anadolu alabalığı (Salmo trutta macrostigma T., 1954), ülkemizde batıdan doğuya; kuzeyden güneye yaygın olarak pek çok su kaynağında, denizden yüksekliği 100-150 m ile 2300 m’ler arasında değişen, yaz döneminde su sıcaklığı 20°C ye kadar yükselebilen habitatlarda diğer Salmo trutta ekotiplerine nazaran, akarsuların daha hızlı aktığı kaynağa yakın bölümlerde ve dağlık bölgelerin yukarı kısımlarında doğal olarak yaşayan bir ekotiptir. Alabalıkların varlığını çeşitli faktörler etkilemektedir. Bunlar; alan kazanma faaliyetleri, arazi kullanımları, kentleşme, madencilik, sanayi, turizm, yaylacılık, ormancılık, zirai mücadele, tarım (ilaçlama ve gübreleme), balıkların göç yollarına ve su yatağına yapılan su ve enerji altyapı projeleri (HES inşaatı), özellikle gökkuşağı a...

Fifty female crayfish (46.20 ± 1.37 g live mass) which caught from Agın Region of the Keban Dam L... more Fifty female crayfish (46.20 ± 1.37 g live mass) which caught from Agın Region of the Keban Dam Lake (Elazıg, Turkey) in March of 2011were examined in the laboratory to evaluate their health status. The exoskeleton was observed for Saprolegnia spp. Mycological investigations demonstrated the presence of hyphae in the area of the abdomen. Saprolegnia spp. was isolated from lesions in infected eggs. Mortalities occurred in fiberglass tanks, after 4 weeks respectively, in the female infected crayfish, with approximately a 38 % cumulative mortality rate (in the last week). In both cases the crayfish were weak, anorexic and lethargic. The main cause of mortality was lesions in infected eggs. Other causes associated with mortality likely can be stressing factors (handling, feeding etc.) in the laboratory.

Acta Ichthyologica et Piscatoria, 2014

The importance of sex, individual size and hide size in the hide use of freshwater crayfish (Asta... more The importance of sex, individual size and hide size in the hide use of freshwater crayfish (Astacus leptodactylus Eschscholtz 1823). The importance of sex, individual size and hide size in the hide use of A. leptodactylus was investigated. It was found that there was not a competition between the new visitor and old hide-owner to have the hide in the same sex, but there was a minor competition between the sexes. However, this competition between the sexes was not at the level of cannibalism. In addition, it was also observed that the individuals of A. leptodactylus used the hides more intensively if there was a relation between hide size and individual size. In conclusion, this study shows that the number and size of hides have a great importance in the use of A. leptodactylus.

Journal of Animal and Veterinary Advances, 2011

Bulletin of Environmental Contamination and Toxicology, 2012

The objective of the present work was to determine the bioaccumulation of arsenic (As), cadmium (... more The objective of the present work was to determine the bioaccumulation of arsenic (As), cadmium (Cd), copper (Cu), lead (Pb), mercury (Hg), uranium (U) and selenium (Se) in gill, liver, and muscle tissues of the fresh water fish Salmo trutta macrostigma (Duméril, 1858) in Munzur Stream, Tunceli, Turkey. The highest concentrations of U (1.83 lg kg-1), Pb (119.84 lg kg-1) and Se (1.31 lg kg-1) were recorded in the gills of S. t. macrostigma. Concentrations of As (46.27 lg kg-1), Cd (109.19 lg kg-1), Hg (16.40 lg kg-1), Cu (18.19 lg kg-1) were recorded at highest levels in the liver. The results showed that there were significant differences in concentrations of As, Cd, Cu, Pb, Se, U and Hg in gill, liver and muscle tissue (p \ 0.05). Heavy metals were within the edible parts of the investigated fish were in the permissible safety levels for human uses.

Asian Journal of Chemistry, 2013

Aquaculture International, 2012

Turkish Journal of Agriculture - Food Science and Technology

The aim of this study was to evaluate the activities of the biotransformation enzymes (Glutatyon ... more The aim of this study was to evaluate the activities of the biotransformation enzymes (Glutatyon S-Transferase (GST) and cytochrome P450 (CYP1A1)) and metabolic enzyme (Lactate dehydrogenase-LDH) in the liver of rainbow trout (Oncorhynchus mykiss) after 24 and 48 hour exposure to 0.5, 1.0 and, 2.0 mg l-1 of Congo red (CR). Enzyme activities were determined by using commercial kits with ELISA method. Congo red altered the activities of GST, CYP1A, and LDH enzymes in liver tissue of O. mykiss in a dose-dependent manner. The statistical differences in GST activities among the groups for 24 and 48 h were significant, but, LDH activities were significant for only 24 h. Exposure duration of CR didn‘t affect the biochemical response of rainbow trout. Thus, CR exposure changed the biotransformation and metabolic enzymes, and the changes of these enzymes activities may be used as a potential bioindicator of the CR exposure.