Temperature Effects Explain Continental Scale Distribution of Cyanobacterial Toxins

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.Peer reviewe

Çinko, civa ve kalay toksitlerinin arthrospira platensis alginin gelişimi ve antioksidan enzimlerinin üzerine etkisi

06.03.2018 tarihli ve 30352 sayılı Resmi Gazetede yayımlanan “Yükseköğretim Kanunu İle Bazı Kanun Ve Kanun Hükmünde Kararnamelerde Değişiklik Yapılması Hakkında Kanun” ile 18.06.2018 tarihli “Lisansüstü Tezlerin Elektronik Ortamda Toplanması, Düzenlenmesi ve Erişime Açılmasına İlişkin Yönerge” gereğince tam metin erişime açılmıştır.Teknolojik ve endüstriyel aktivitelerin artması sonucu oluşan metal kirliliği, besin zinciri içerisinde tehlikeli bir boyuta ulaşabilmektedir. Tatlı su ekosistemleri de metal kirliliğinden büyük zarar görmektedir. Özellikle sudaki besin zincirinin ilk basamağını oluşturan alglerin metal stresinden etkilenmesine bağlı olarak ekosistemin tür kompozisyonu değişmekte ve bu durum besin zincirinin üst basamağındaki canlıları da etkilemektedir. Ekosistemin gidişatının izlenmesi ve suda tolere edilebilen maksimum metal konsantrasyonlarının belirlenmesi için yapılan ekotoksikoloji çalışmalarında algler geniş ölçekte kullanılmaktadır. Bu çalışmalarda metal stresine bağlı olarak alg hücrelerinde meydana gelen değişiklikler, toleransı olmayan ve toleranslı yüksek olan algler belirlenmektedir. Alg hücreleri metal stresine karşı çok çeşitli tolerans mekanizmaları geliştirmişlerdir. Bu tolerans mekanizmalarından birisi de alglerde metal etkili oksidatif strese karşı antioksidan enzimlerin aktivitelerinin düzenlenmesine bağlı olarak gösterilen toleranstır. Bu çalışmada A. platensis algi çinko, kalay ve civa ağır metallerinin farklı konsantrasyonlarına maruz bırakılmıştır. Böylece ağır metalin türüne ve konsantrasyonuna bağlı olarak canlının klorofil-a miktarındaki, biyokütlesindeki ve antioksidan parametrelerindeki (SOD, APOD ve GR) değişim belirlenmiştir. Ağır metal seviyesindeki artışın hücresel hasara neden olduğu tespit edilmiştir. Çinko, kalay ve civa uygulanan örneklerde konsantrasyon artışına ve zamana bağlı olarak hem biyokütlede hem de klorofil-a miktarında kontrole göre düşüş olmuştur. Antioksidan parametrelerdeki değişimler incelendiğinde; SOD aktivitesinde kontrole göre en fazla düşüş civa uygulanan örneklerde görülmüştür. APOD aktivitesinde kalay uygulanan örnekler kontrole göre en fazla düşüşü göstermişlerdir. GR aktivitesinde ise çinko, kalay ve civa uygulanan örneklerin tamamında kontrole göre önemli derecede azalmalar görülmüştür. Sonuç olarak, kalayın civa ve çinko ile karşılaştırıldığında, daha toksik olduğu ve toksik etkisini özellikle APOD enziminin sentezi ve aktivitesi üzerindeki selektif etkisi ile gösterdiği söylenebilir. Anahtar kelimeler: Arthrospira platensis, klorofil-a, biyokütle, ağır metaller, antioksidan enzimler.Metal pollution as a result of the technological and industrial activities can reach to hazardous level at food chain. Fresh water ecosystems have been damaged exceedingly from metal contamination. Especially the algae that constitute the first step of the food chain in water, are affected by metal stress and this situation affects the species composition of ecosystems and the top of the food chain. Algae are used in large-scale both in ecosystem monitoring studies and water eco-toxicology studies that conducted to determine the maximum tolerated concentrations of metals. Due to the metal stress, changes in the algae cells, low tolerance and high tolerance algae are determined in these studies. Algae cells have developed a wide variety of tolerance mechanisms against metal stress. One of these metal tolerance mechanisms in algae is that depending on the organization of antioxidant enzymes against metal effective oxidative stress. In this study, A .platensis was exposed to different concentrations of heavy metals such as zinc, tin and mercury. In this manner, changes in chlorophyll-a concentration biomass, antioxidant enzymes activites (SOD, APOD, GR) were determined. The increase in the level of heavy metals have been found to cause cellular damage. Zinc, mercury and tin applications decreased both biomass and chlorophyll-a content in a time and concentration dependent manner when compared to controls. According to our results, tin was found to be the most effective heavy metal that causes the most significant decreases in biomass and chlorophyll a content. Our results showed that mercury applications caused to maximum decrease in SOD activity while APOD activity was decreased as a result of tin applications. Zinc, mercury and tin concentrations led to the significant reduction in GR activity as compared to control values. The treatments with increasing concentrations of zinc, tin and mercury progressively inhibited the growth of algae and chlorophyll-a valves during 7 days. The activity of SOD was mostly decreased by mercury, while the activity of SOD was by tin. The activity of GR were by both of the heavy metals. Keywords: Arthrospira platensis, chlorophyll-a, biomass, heavy metals, antioxidant enzymes

Salisilik asitin, arthrospira platensis (nordstedt) gomont alginin gelişimi ve toplam fenolik içeriği üzerine etkisi

Bu çalışma, 25-28 Ağustos 2014 tarihleri ​​arasında Bursa Türkiye'de düzenlenen “6. Ulusal Limnoloji Sempozyumu” nda sunulmuştur.In this study, the effects of salicylic acid on growth of Arthrospira platensis (Nordstedt) Gomont were investigated. For this reason, different concentrations of salicylic acid (0.5, 1, 1.5, 2 g L-1 ) were given to cultures, then changes of optical density, chlorophyll-a and total phenolic contents were assessed. OD and methanol extract of chlorophyll-a and phenolic contents were measured by spectrophotometrically. All parameters decreased with increasing salicylic acid concentrations and LC50 value was 1.5 mg L-1 for ninth day. Growth of A. platensis declined with salicylic acid treatment.Bu çalışmada salisilik asitin, Arthrospira platensis (Nordstedt) Gomont alginin gelişimi üzerine etkisi araştırılmıştır. Salisilik asitin farklı konsantrasyonları (0.5, 1, 1.5, 2 g L-1) alg kültürüne verilerek optik yoğunlukta (OD), klorofil-a konsantrasyonunda ve toplam fenolik içerikte meydana gelen değişiklikler ölçülmüştür. OD, klorofil-a ve fenolik içerik spektrofotometrik olarak belirlenmiştir. Artan salisilik asit konsantrasyonuna bağlı olarak tüm parametrelerde azalma görülmüştür ve deneyin dokzuncu gününde LC50 değeri 1.5 mg L-1 olarak belirlenmiştir. Sonuç olarak salisilik asit uygulamasının A. platensis alginin gelişimini azalttığı görülmektedir

Evaluation of Azadirachtin on

Azadirachtin (Aza) used as insecticide due to inhibiting growth of insects and preventing them from feeding on plants. To understand the effects of contamination of this insecticide on phototrophs, and to determine the responses of these organisms against these insecticides are extremely important in understanding how the ecosystem is affected. In this study, chlorophyll-a amount, OD 560 and antioxidant parameters (total SOD, APX, GR, Proline, MDA and H2O2) were determined in order to understand the effect of Aza on Arthrospira platensis Gomont. Aza was applied between 0–20 μg mL−1 concentrations for 7 days in the study. Enzyme analysis was conducted at the end of the 7th day. There was a statistically significant decrease in the absorbance of OD560 and the chlorophyll-a content in A. platensis cultures exposed to the Aza (0–20 μg mL−1) during 7 days due to the increase in pesticide levels. SOD activity decreased at 8, 16 and 20 μg mL−1 concentrations; GR enzyme activity showed a significant decrease compared to the control at a concentration of 20 μg mL−1. APX activity did not change significantly compared to control. The MDA content increased significantly at 16 and 20 μg mL−1 concentrations. The H2O2 content significantly increased at 12, 16 and 20 μg mL−1 concentrations (p < 0.05) while the free proline content decreased at 4 μg mL−1 concentration (p < 0.05). As a result, regarding the Aza concentrations used in this study may be a step to prevent pesticide pollution in the environment.To understand the effects of contamination of insecticides onphototrophs, and to determine the responses of these organisms against these chemicals are extremely important in understanding how the ecosystem is affected. Azadirachtin used as insecticide due to inhibiting growth of insects and preventing them feeding on plants and it contaminates to aquatic ecosystems. Azadirachtin effects to a phytoplanktonic organism as called Arthrospira platensis and creates oxidative stress in their cells

Stratification strength and light climate explain variation in chlorophyll a at the continental scale in a European multilake survey in a heatwave summer

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 degrees 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.Peer reviewe

Stratification strength and light climate explain variation in chlorophyll a at the continental scale in a European multilake survey in a heatwave summer

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