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  • Öğe
    Influence of some knitting and finishing parameters on the snag resistance of polyethylene terephthalate (PET) knit fabric
    (SAGE Publications Ltd, 2021) Yibar, Mehmet Fahri; Öǧüt, Hamdi; Cingu, Neslihan; Cetin, Suna; Yatikci, Tugce Koroglu; Yıldırım, Kenan
    To assess the effects of fabric take-up, yarn tension, feeder position, and yarn feeder material on the occurrence of snagging, fabrics produced with two different finishing processes, were subjected to longitudinal or transversal 100, 300, and 600 revolutions, and the degree of snagging was measured and compared afterwards with gray fabric. Our results showed that, during the knitting process, the use of ceramic yarn feeders resulted in significantly fewer snags compared with metal yarn feeders. The gray fabric, having no finishing, was fragile and easily snagged, whereas the fabric treated by a finishing process – either drying in relaxed condition (Treatment A) or under stress conditions (Treatment B) – was more resistant to snagging. Moreover, the snagging property of the gray fabric tended to increase with increasing longitudinal or transversal 100, 300, or 600 revolutions. Slight increases in snagging were also present in fabrics having Treatment A or Treatment B at the same revolutions, but the differences were not statistically important (P > 0.05). Frequency of snags was higher when revolutions were transversal rather than on longitudinal direction. Yarn tension and feeder position had no effect on snagging degree, while fabric take-up had limited effect. For acquiring a fabric resistant to snagging, the gray fabric produced with ceramic yarn guiders during the knitting process should be subjected to drying under relaxed condition. We also suggest that quality control tests be carried out taking the results of our study into consideration.
  • Öğe
    Characterization and antibacterial activity of gelatin–gellan gum bilayer wound dressing
    (Taylor and Francis Ltd., 2021) Özkahraman B.; Özbaş Z.; Bayrak G.; Tamahkar, Emel; Perçin I.; Kılıç Süloğlu A.; Boran F.
    Bilayer wound dressing systems consisting of various biopolymers have been preferred in biomedical applications due to its enhanced advantages in comparison with conventional systems. The aim of this research was to develop a novel bilayer wound dressing based on gelatin (G) and gellan gum (GG). The bilayer was composed of an upper layer impregnated with antibiotic drug sodium ampicillin and a drug-free lower sponge layer. The bilayer hydrogels were characterized by FTIR, TGA, DSC and SEM analyses including swelling behaviors and hydrolytic degradation tests. To achieve faster healing of the wound by prevention of the bacterial infection, the bilayer hydrogels were developed as antibiotic-releasing vehicles. Herein, release study of sodium ampicillin was performed in PBS to simulate the physiological micro-environment. Additionally, cyto-compatibility tests of L929 fibroblast cells showed the high proliferation and survival through drug-loaded GG and G hydrogels (GG-G-D) after 24h, 48h and 72h incubation. This novel GG-G bilayer hydrogel could be a good candidate as wound dressing.
  • Öğe
    Bacterial cellulose/poly vinyl alcohol based wound dressings with sustained antibiotic delivery
    (Springer Science and Business Media Deutschland GmbH, 2021) Tamahkar, Emel
    The current work was aimed to prepare bacterial cellulose/poly vinyl alcohol (BC/PVA) wound dressings loaded with antibiotic which were prepared via freeze-thawing. The swelling ratio of BC/PVA hydrogels was in the range of 188–240%. The water loss percentage of BC was improved with the addition of PVA. 30% of the cumulative ampicillin delivery from BC/PVA hydrogels was achieved during 120 h suggesting significant role of PVA incorporation since 50% of ampicillin was released from BC after 24 h. BC/PVA hydrogels showed great antibacterial activity against E.coli and S. aureus. The results revealed that BC/PVA hydrogels presented great potential as wound dressings with high swelling ratio, low water loss percentage and slow antibiotic release properties.
  • Öğe
    An enzyme immobilized microreactor for continuous-flow biocatalysis of ginsenoside Rb1
    (John Wiley and Sons Ltd, 2021) Kazan, Aslıhan; Hu X.; Stahl A.; Frerichs H.; Smirnova I.; Yesil-Celiktas O.
    Ginsenoside Rb1 is one of the major bioactive components of Panax ginseng C.A. Meyer (Araliaceae), a medicinal plant that has been used for therapeutic purposes for thousands of years in Asian countries. The pharmaceutical activity of ginsenoside Rb1 highly depends on molecular structure and its deglycosylated metabolites are known to be more potent bioactive compounds. However, these deglycosylated ginsenosides do not exist naturally so they are usually obtained by poorly selective methods, like chemical hydrolysis. RESULTS: In this study, the development and characterization of an alginate-based immobilized enzyme microreactor for the catalytic conversion of ginsenoside Rb1 to more bioactive metabolites have been reported. Enzyme kinetic parameters were calculated and characterization tests (such as determination of surface area of alginate matrix, long-term use, and effect of residence time on conversion yield) were conducted. The system was operated under continuous-flow conditions and compared with acidic and batch enzymatic hydrolysis experiments, as conventional approaches. The enzymatic microreactor showed an enhanced activity by producing 13-fold higher amount of ginsenoside F2 than batch enzymatic hydrolysis. CONCLUSION: Obtained results indicated that the newly developed enzymatic microreactor could successfully convert ginsenoside Rb1 to more active metabolites and have a potential for the biocatalysis of multiple ginsenosides, as well as pharmaceutically active compounds.
  • Öğe
    Stratification strength and light climate explain variation in chlorophyll a at the continental scale in a European multilake survey in a heatwave summer
    (John Wiley and Sons Inc, 2021) Donis D.; Mantzouki E.; McGinnis D.F.; Vachon D.; Gallego I.; Yılmaz, Mete
    To determine the drivers of phytoplankton biomass, we collected standardized morphometric, physical, and biological data in 230 lakes across the Mediterranean, Continental, and Boreal climatic zones of the European continent. Multilinear regression models tested on this snapshot of mostly eutrophic lakes (median total phosphorus [TP] = 0.06 and total nitrogen [TN] = 0.7 mg L−1), and its subsets (2 depth types and 3 climatic zones), show that light climate and stratification strength were the most significant explanatory variables for chlorophyll a (Chl a) variance. TN was a significant predictor for phytoplankton biomass for shallow and continental lakes, while TP never appeared as an explanatory variable, suggesting that under high TP, light, which partially controls stratification strength, becomes limiting for phytoplankton development. Mediterranean lakes were the warmest yet most weakly stratified and had significantly less Chl a than Boreal lakes, where the temperature anomaly from the long-term average, during a summer heatwave was the highest (+4°C) and showed a significant, exponential relationship with stratification strength. This European survey represents a summer snapshot of phytoplankton biomass and its drivers, and lends support that light and stratification metrics, which are both affected by climate change, are better predictors for phytoplankton biomass in nutrient-rich lakes than nutrient concentrations and surface temperature.
  • Öğe
    Denizel diatom izolasyonu, tanımlanması ve besin maddelerinin diatom büyümesi üzerine etkisinin incelenmesi
    (2019) Çınar, Sait; Özçimen, Didem; Yılmaz, Mete
    Son yıllarda oldukça dikkat çeken mikroalgler sağlık, gıda, kozmetik, çevre ve biyoyakıt üretimi alanlarında kullanım potansiyeli bulunan yeni nesil hammadde kaynaklarıdır. Bu çalışmada, hem bulunma miktarı hem de fonksiyonları bakımından önemli bir mikroalg sınıfı olan diatomların eldesi hedeflenerek, Marmara Denizi Mudanya kıyılarından toplanan su örnekleri üzerinde izolasyon çalışması gerçekleştirilmiş ve elde edilen izolatın moleküler analizi yapılarak Pleurosigma sp. olduğu tespit edilmiştir. İzole Pleurosigma sp. farklı konsantrasyonlarda azot, fosfor ve silisyum içeren besin solüsyonlarında yetiştirilip istatistiksel olarak yorumlandığında, diatomun hücre yoğunluğunun, silisyum ve azot artışı ile belirgin şekilde pozitif korelasyon gösterdiği, ancak hücre yoğunluğunun 0,0096 mM fosfat konsantrasyonunda maksimum seviyeye ulaştığı gözlenmiştir. Yapılan karakterizasyon çalışmalarında, diatomun önemli miktarda silisyumlu yapılar içerdiği ve kül içeriğinin yüksek olduğu, yağ asidi profilinin literatürde diatomlarda sıklıkla karşılaşılan yağ asitleriyle örtüştüğü görülmüştür.
  • Öğe
    Dinoflagellate cyst assemblages in surface sediments of southwestern black sea and Çanakkale strait (dardanelles)
    (Parlar Scientific Publications, 2015) Aydin, H.; Balcı, Muharrem; Uzar, S.; Balkis, N.
    In order to document the distribution of dinoflagellate cyst assemblages, eight surface sediment samples were collected in surface sediments from southwestern Black Sea and Çanakkale Strait. A total of 25 cyst types and 1 unknown cyst type were identified. Samples displays low total cyst concentrations with values ranging from 8 to 346 cyst g-1 dry weight sediment. Autotrophic dinoflagellates highly and significantly contributes (p<0.01) to the total cyst concentration. Lingulodinium machaerophorum, cyst type of Al-exandrium minutum and Spiniferites bulloideus were dominant at the sampling points. Higher cyst concentration and diversity observed at stations in Black Sea could be linked to the type of sediment. Small-sized sediment (sand-silt) were mostly dominant at the Black Sea stations compare to the more sandy type sediment of Çanakkale Strait. Present study provides the first modern dinoflagellate cyst records from surface sediments of southwestern Black Sea and Çanakkale Strait. © by PSP.
  • Öğe
    An alginate-poly(acrylamide) hydrogel with TGF-?3 loaded nanoparticles for cartilage repair: Biodegradability, biocompatibility and protein adsorption
    (Elsevier B.V., 2021) Saygili, E.; Kaya, E.; Ilhan-Ayisigi, E.; Saglam-Metiner, P.; Alarcin, E.; Kazan, Aslıhan; Girgic, E.
    Current implantable materials are limited in terms of function as native tissue, and there is still no effective clinical treatment to restore articular impairments. Hereby, a functionalized polyacrylamide (PAAm)-alginate (Alg) Double Network (DN) hydrogel acting as an articular-like tissue is developed. These hydrogels sustain their mechanical stability under different temperature (+4 °C, 25 °C, 40 °C) and humidity conditions (60% and 75%) over 3 months. As for the functionalization, transforming growth factor beta-3 (TGF-?3) encapsulated (NPTGF-?3) and empty poly(lactide-co-glycolide) (PLGA) nanoparticles (PLGA NPs) are synthesized by using microfluidic platform, wherein the mean particle sizes are determined as 81.44 ± 9.2 nm and 126 ± 4.52 nm with very low polydispersity indexes (PDI) of 0.194 and 0.137, respectively. Functionalization process of PAAm-Alg hydrogels with ester-end PLGA NPs is confirmed by FTIR analysis, and higher viscoelasticity is obtained for functionalized hydrogels. Moreover, cartilage regeneration capability of these hydrogels is evaluated with in vitro and in vivo experiments. Compared with the PAAm-Alg hydrogels, functionalized formulations exhibit a better cell viability. Histological staining, and score distribution confirmed that proposed hydrogels significantly enhance regeneration of cartilage in rats due to stable hydrogel matrix and controlled release of TGF-?3. These findings demonstrated that PAAm-Alg hydrogels showed potential for cartilage repair and clinical application. © 2021 Elsevier B.V.
  • Öğe
    DINOFLAGELLATE CYST ASSEMBLAGES IN SURFACE SEDIMENTS OF SOUTHWESTERN BLACK SEA AND CANAKKALE STRAIT (DARDANELLES)
    (Parlar Scientific Publications (P S P), 2015) Aydin, Hilal; Balcı, Muharrem; Uzar, Serdar; Balkis, Neslihan
    In order to document the distribution of dinoflagellate cyst assemblages, eight surface sediment samples were collected in surface sediments from southwestern Black Sea and Canakkale Strait. A total of 25 cyst types and 1 unknown cyst type were identified. Samples displays low total cyst concentrations with values ranging from 8 to 346 cyst g(-1) dry weight sediment. Autotrophic dinoflagellates highly and significantly contributes (p<0.01) to the total cyst concentration. Lingulodinium machaerophorum, cyst type of Alexandrium minutum and Spiniferites bulloideus were dominant at the sampling points. Higher cyst concentration and diversity observed at stations in Black Sea could be linked to the type of sediment. Small-sized sediment (sand-silt) were mostly dominant at the Black Sea stations compare to the more sandy type sediment of Canakkale Strait. Present study provides the first modern dinoflagellate cyst records from surface sediments of southwestern Black Sea and Canakkale Strait.
  • Öğe
    Dinoflagellate resting cysts in recent marine sediments from the Gulf of Gemlik (Marmara Sea, Turkey) and seasonal harmful algal blooms
    (Taylor & Francis Ltd, 2016) Balkis, Neslihan; Balcı, Muharrem; Giannakourou, Antonia; Venetsanopoulou, Amalia; Mudie, Petra
    Thirty-four dinoflagellate cyst taxa were found in surface sediment (0-2 cm) at five stations (60-100-m water depth) in the Gulf of Gemlik, Marmara Sea, during four seasons from August 2011 to May 2012. Lingulodinium machaerophorum, Operculodinium centrocarpum and Selenopemphix quanta dominated cyst assemblages in the polluted gulf, where nutrient-rich surface water was stratified during most seasons and bottom water was hypoxic. Twelve cyst taxa were incubated and produced motile cells that reproduced and survived 14-15 days. Highest cyst species number (33) occurred in summer; maximum number of cysts (living and empty) per cm 3 wet sediment was in spring, with the annual range from 1520 (fall) to 108,000 (spring). Nine taxa (Brigantedinium simplex, L. machaerophorum, O. centrocarpum, S. quanta, Spiniferites mirabilis, Spiniferites ramosus, cysts of Alexandrium sp., Scrippsiella trifida and S. trochoidea) were found in all seasons at all stations. The harmful dinoflagellates L. machaerophorum and cysts of S. trochoidea and Alexandrium sp. were the most abundant species. The cyst of the toxic species, Cochlodinium sp., is reported for the first time from Turkey. Other HAB species included A. tamarense, Protoceratium reticulatum, Heterocapsa triquetra and Gymnodinium catenatum/nolleri. Relative abundance of potentially toxic dinoflagellates (74%-92% of total cysts cm(-3)) was always higher than nontoxic species, and percentage abundance of cysts cm(-3) produced by autotrophs (19/34 total species) almost always exceeded those of heterotrophs. Although distributions of the resting cyst taxa were significantly influenced by surface temperature, dissolved oxygen and total water depth, surface salinity was the strongest predictor for cyst occurrences.
  • Öğe
    Photobacterium damselae subsp damselae, an Emerging Fish Pathogen in the Black Sea: Evidence of a Multiclonal Origin
    (Amer Soc Microbiology, 2016) Terceti, Mateus S.; Öğüt, Hamdi; Osorio, Carlos R.
    Photobacterium damselae subsp. damselae is considered to be an emerging pathogen of marine fish of importance in aquaculture, with a notable increase in its geographical distribution during the last several years. In this study, we carried out for the first time to our knowledge a genetic and pathobiological characterization of 14 strains isolated from sea bass (Dicentrarchus labrax) reared in the Southeastern Black Sea, where high mortalities were observed at two aquaculture farms during the summer and autumn of 2011. Heterogeneity was evidenced among strains in phenotypical traits, such as sucrose fermentation, motility, and hemolysis. Although 11 of 14 isolates were hemolytic, we found that all of the isolates lacked the pPHDD1 virulence plasmid that encodes the phospholipase-D damselysin (Dly) and the pore-forming toxin PhlyP, two hemolysins previously reported to constitute major virulence factors for turbot. Subsequent PCR and sequencing analyses demonstrated that the 11 hemolytic isolates harbored a complete hlyA(ch) gene, a chromosome I-borne gene that encodes HlyA(ch) hemolysin, whereas the three nonhemolytic isolates contained hlyA(ch) pseudogenes caused by insertion sequence elements. Virulence challenges with two representative strains revealed that, albeit less virulent than the pPHDD1-harboring strain RM-71, the plasmidless hlyA(ch)-positive and hlyA(ch)-negative Black Sea isolates were pathogenic for sea bass. A phylogenetic analysis based on the toxR gene sequence uncovered a greater diversity in the isolates, indicating that the presence of this pathogen in the Black Sea was not caused by the introduction and spread of a single virulent clone but by the proliferation of different clones.
  • Öğe
    Evaluation of the in vitro antioxidant, cytotoxic and genotoxic/antigenotoxic effects of resveratrol
    (Elsevier Ireland Ltd, 2016) Taner, Gökçe; Aydin, S.; Aytac, Z.; Basaran, A. A.; Basaran, N.
    [No Abstract Available]
  • Öğe
    Comparisons of antioxidant, cytotoxic and genotoxic/antigenotoxic effects of pycnogenol and rosmarinic acid
    (Elsevier Ireland Ltd, 2016) Taner, Gökçe; Aydin, S.; Aytac, Z.; Basaran, A. A.; Basaran, N.
    [No Abstract Available]
  • Öğe
    Algal toxins and producers in the marine waters of Qatar, Arabian Gulf
    (Pergamon-Elsevier Science Ltd, 2016) Al Muftah, Abdulrahman; Selwood, Andrew I.; Foss, Amanda J.; Al-Jabri, Hareb Mohammed S. J.; Potts, Malcolm; Yılmaz, Mete
    Harmful Algal Bloom species are ubiquitous and their blooms occur in the Arabian Gulf. In this study, two cruises were performed in 2012 and 2013 to collect phytoplankton samples from 4 sites in the Arabian Gulf. Toxin analyses of phytoplankton samples for 32 algal toxins from 5 different toxin groups were conducted on the samples using both enzyme linked immunosorbent assay (ELISA) and liquid chromatography tandem mass spectrometry (LC-MS/MS). Results demonstrated, for the first time, the presence of paralytic shellfish toxins (PSTs), diarrhetic shellfish toxin (DST), amnesic shellfish toxin (AST), cyclic imines (CIs) and polyether-lactone toxins in freeze-dried phytoplankton samples. Four Vulcanodinium rugosum cultures were established from field samples and these proved to contain between 603 and 981 ng pinnatoxin (PnTx) H per mg dry weight in addition to being positive for portimine. These strains from Qatar clustered with strains from Japan and Florida based on large subunit rRNA and rRNA internal transcribed spacer gene sequences. (C) 2016 Elsevier Ltd. All rights reserved.
  • Öğe
    Resveratrol Protects Sepsis-Induced Oxidative DNA Damage in Liver and Kidney of Rats
    (Galenos Yayincilik, 2016) Aydin, Sevtap; Sahin, Tevfik Tolga; Bacanli, Merve; Taner, Gökçe; Basaran, Arif Ahmet; Aydin, Mehtap
    Background: The increases of free radicals have been proposed to be involved in the pathogenesis of sepsis, which leads to multiple-organ dysfunction syndromes. The uses of antioxidants as a complementary tool in the medical care of oxidative stress-related diseases have attracted attention of researchers. Resveratrol (RV) has suggested being antioxidant, anti-proliferative, and anti-inflammatory effects in various experimental models and clinical settings. Aims: This study was undertaken to evaluate the protective effects of RV on oxidative DNA damage induced by sepsis in the liver and kidney tissues of Wistar albino rats. Study Design: Animal experimentation. Methods: Four experimental groups consisting of eight animals for each was created using a total of thirty-two male Wistar albino rats. Sham group was given 0.5 mL of saline intra-peritoneal (ip) only following laparatomy. Sepsis group was given 0.5 mL saline ip only following the induction of sepsis. RV-treated group was given a dose of 100 mg/kg ip RV in 0.5 mL saline following laparatomy. RV-treated sepsis group was given 100 mg/kg ip RV in 0.5 mL saline following the induction of sepsis. A model of sepsis was created by cecal ligation and puncture technique. In the liver and kidney tissues, oxidative stress parameters (malondialdehyde (MDA), reduced glutathione (GSH), superoxide dismutase (SOD), glutathione peroxidase (GPX)) and a proinflammatory cytokine (tumor necrosis factor alpha (TNF-alpha)), were evaluated spectrophotometrically and DNA damage was determined by the alkaline single cell gel electrophoresis (comet assay) technique using formamidopyrimidine DNA glycosylase protein. Results: In the RV-treated sepsis group, the levels of MDA and TNF-alpha were lower and GSH levels, SOD and GPX activities were higher than in the septic rats (p<0.05). RV treatment significantly reduced the sepsis-induced oxidative DNA damage in the liver and kidney cells (p<0.05). Conclusion: It is suggested that RV treatment might reduce the sepsis-induced oxidative DNA damages in sepsis-related diseases; however, there is a need for more studies to clear up the protective mechanisms of RV against sepsis.
  • Öğe
    Use of in vitro assays to assess the potential cytotoxic, genotoxic and antigenotoxic effects of vanillic and cinnamic acid
    (Taylor & Francis Ltd, 2017) Taner, Gökçe; Vardar, Deniz Ozkan; Aydin, Sevtap; Aytac, Zeki; Basaran, Ahmet; Basaran, Nursen
    Vanillic acid (VA) found in vanilla and cinnamic acid (CA) the precursor of flavonoids and found in cinnamon oil, are natural plant phenolic acids which are secondary aromatic plant products suggested to possess many physiological and pharmacological functions. In vitro and in vivo experiments have shown that phenolic acids exhibit powerful effects on biological responses by scavenging free radicals and eliciting antioxidant capacity. In the present study, we investigated the antioxidant capacity of VA and CA by the trolox equivalent antioxidant capacity (TEAC) assay, cytotoxicity by neutral red uptake (NRU) assay in Chinese Hamster Ovary (CHO) cells and also the genotoxic and antigenotoxic effects of these phenolic acids using the cytokinesis-blocked micronucleus (CBMN) and the alkaline comet assays in human peripheral blood lymphocytes. At all tested concentrations, VA (0.17-67.2 mu g/ml) showed antioxidant activity but CA (0.15-59.2 mu g/ml) did not show antioxidant activity against 2,2-azino-bis (3-ethylbenz-thiazoline-6-sulphonic acid) (ABTS). VA (0.84, 4.2, 8.4, 16.8, 84 and 168 mu g/ml) and CA (0.74, 3.7, 7.4, 14.8, 74, 148 mu g/ml) did not have cytotoxic and genotoxic effects alone at the studied concentrations as compared with the controls. Both VA and CA seem to decrease DNA damage induced by H2O2 in human lymphocytes.
  • Öğe
    Assessment of DNA damage in ceramic workers
    (Oxford Univ Press, 2018) Anlar, Hatice Gul; Taner, Gökçe; Bacanli, Merve; Iritas, Servet; Kurt, Turker; Tutkun, Engin
    It is known that ceramic workers are potentially exposed to complex mixture of chemicals such as silica, inorganic lead, lime, beryllium and aluminum that can be associated with an increased risk of several diseases. All operations in the ceramic industries such as mixing, moulding, casting, shaking out and finishing jobs, have been associated with the higher exposure levels and in most of the silica-related industries, average overall exposure exceeded permissible exposure levels for respirable crystalline silica. The aim of this study was to evaluate the possible genotoxic damage in ceramic workers exposed to complex mixture of chemicals mainly crystalline silica. For this purpose, the blood and buccal epithelial cell samples were taken from the ceramic workers (n = 99) and their controls (n = 81). The genotoxicity was assessed by the alkaline comet assay in isolated lymphocytes and whole blood. Micronucleus (MN), binucleated (BN), pyknotic (PYC), condensed chromatin (CC), karyolytic (KYL), karyorrhectic (KHC) and nuclear bud (NBUD) frequencies in buccal epithelial cells and plasma 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) levels were also evaluated. In the study, 38 workers were diagnosed with silicosis, 9 workers were suspected to have silicosis, whereas 52 workers were found to be healthy. DNA damage in blood and lymphocytes; MN, CC + KHC, PYC frequencies in buccal epithelial cells and 8-oxodG levels in plasma were increased in workers compared to their controls. These results showed that occupational chemical mixture exposure in ceramic industry may cause genotoxic damage that can lead to important health problems in the workers.
  • Öğe
    Temperature Effects Explain Continental Scale Distribution of Cyanobacterial Toxins
    (Mdpi, 2018) Mantzouki, Evanthia; Lurling, Miquel; Fastner, Jutta; Domis, Lisette de Senerpont; Wilk-Wozniak, Elzbieta; Yılmaz, Mete
    Insight into how environmental change determines the production and distribution of cyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus on hepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g., anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to their potency. Most studies examine the relationship between individual toxin variants and environmental factors, such as nutrients, temperature and light. In summer 2015, we collected samples across Europe to investigate the effect of nutrient and temperature gradients on the variability of toxin production at a continental scale. Direct and indirect effects of temperature were the main drivers of the spatial distribution in the toxins produced by the cyanobacterial community, the toxin concentrations and toxin quota. Generalized linear models showed that a Toxin Diversity Index (TDI) increased with latitude, while it decreased with water stability. Increases in TDI were explained through a significant increase in toxin variants such as MC-YR, anatoxin and cylindrospermopsin, accompanied by a decreasing presence of MC-LR. While global warming continues, the direct and indirect effects of increased lake temperatures will drive changes in the distribution of cyanobacterial toxins in Europe, potentially promoting selection of a few highly toxic species or strains.
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    Paralytic shellfish toxin producing Aphanizomenon gracile strains isolated from Lake Iznik, Turkey
    (Pergamon-Elsevier Science Ltd, 2018) Yılmaz, Mete; Foss, Amanda J.; Selwood, Andrew I.; Ozen, Mihriban; Boundy, Michael
    Aphanizomenon gracile is one of the most widespread Paralytic Shellfish Toxin (PST) producing cyanobacteria in freshwater bodies in the Northern Hemisphere. It has been shown to produce various PST congeners, including saxitoxin (STX), neosaxitoxin (NEO), decarbamoylsaxitoxin (dcSTX) and gonyautoxin 5 (GTX5) in Europe, North America and Asia. Three cyanobacteria strains were isolated in Lake Iznik in northwestern Turkey. Morphological characterization of these strains suggested all three strains conformed to classical taxonomic identification of A. gracile with some differences such as clumping of filaments, partially hyaline cells in some filaments and longer than usual vegetative cells. Sequences of 16S rRNA gene of these strains were placed within an A. gracile cluster including the majority of PST producing strains, confirming the identification of these strains as A. gracile. These new strains possessed saxitoxin biosynthesis genes sxtA, sxtG and their sequences clustered with those of other A. gracile. Liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis demonstrated the presence of NEO, STX, dcSTX and decarbamoylneosaxitoxin (dcNEO) in all strains. This is the first report of a PST producer in any water body in Turkey and first observation of dcNEO in an A. gracile culture. (C) 2018 Elsevier Ltd. All rights reserved.
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    A European Multi Lake Survey dataset of environmental variables, phytoplankton pigments and cyanotoxins
    (Nature Publishing Group, 2018) Mantzouki, Evanthia; Campbell, James; van Loon, Emiel; Visser, Petra; Konstantinou, Iosif; Yılmaz, Mete
    Under ongoing climate change and increasing anthropogenic activity, which continuously challenge ecosystem resilience, an in-depth understanding of ecological processes is urgently needed. Lakes, as providers of numerous ecosystem services, face multiple stressors that threaten their functioning. Harmful cyanobacterial blooms are a persistent problem resulting from nutrient pollution and climate-change induced stressors, like poor transparency, increased water temperature and enhanced stratification. Consistency in data collection and analysis methods is necessary to achieve fully comparable datasets and for statistical validity, avoiding issues linked to disparate data sources. The European Multi Lake Survey (EMLS) in summer 2015 was an initiative among scientists from 27 countries to collect and analyse lake physical, chemical and biological variables in a fully standardized manner. This database includes in-situ lake variables along with nutrient, pigment and cyanotoxin data of 369 lakes in Europe, which were centrally analysed in dedicated laboratories. Publishing the EMLS methods and dataset might inspire similar initiatives to study across large geographic areas that will contribute to better understanding lake responses in a changing environment.