Kinetic Behaviour of Glucose 6-Phosphate Dehydrogenase and 6-Phosphogluconate Dehydrogenase in Different Tissues of Rainbow Trout (Oncorhynchus mykiss) Exposed to Non-Lethal Concentrations of Cadmium

The effects of cadmium (Cd) on the enzymatic activities of glucose 6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (6PGD) were investigated in the gill, liver and kidney tissues of rainbow trout (Oncorhynchus mykiss). Three test groups of fish were subjected to increasing concentrations (1, 3 and 5 mg/l) of cadmium (Cd) in vivo, respectively. The G6PD and 6PGD activities in the gill, liver, and kidney tissues of each group of fish were measured on days 1, 3, 5 and 7. G6PD and 6PGD enzyme activities, measured in gill, liver and kidney homogenates, were stimulated by various concentrations (1, 3, and 5 mg/l) of cadmium. Although the dose-response pattern of G6PD enzyme activities in liver and kidney tissue was very similar, that in gill was different from both other tissues. The enzyme activity of G6PD enzyme was significantly stimulated after three days (Day 3) in liver and kidney tissues at a dose of 1 mg/l Cd (p p p p p p < 0.05) in liver and kidney tissues at the doses of 3 and 1 mg/l Cd. The stimulation effect of cadmium on the three tissues studied was also calculated; for both of the enzymes (G6PD and 6PGD), the enzyme activity levels were stimulated by approximately 60% and 38% in gills, 68% and 44% in liver, and 67% and 41% in kidneys, respectively, over the base-line enzyme activity of the control groups during the sevenday experimental period. These findings indicate that tissue G6PD and 6PGD enzymes function to protect against cadmium toxicity

Use of Ridge and principal component regression analysis methods in multicollinearity

Ridge ve temel bileşenler regresyon analiz yöntemleri, çok değişkenli regresyon verilerini analiz etmek için kullanılan istatistik analiz yöntemleridir. Çoklu bağlantı ortaya çıktığında en küçük kareler tahminleri sapmasız olmasına karşın tahminlerin varyansları büyük olduğundan gerçek değerlerinden oldukça uzakta olabilmektedirler. Bir derece yanlı regresyon tahminlerine izin vermek suretiyle ridge ve temel bileşenler regresyon standart hataları indirgenir. Dolayısıyla çoklu bağlantı durumu mevcut olduğunda en küçük kareler metoduna alternatif olarak ridge ve temel bileşenler regresyon metotları kullanılabilir. Bu araştırmada farklı yaşlara sahip 91 adet sazan balığından elde edilen çeşitli vücut ölçüleri kullanılarak karkas ağırlığını tahminleyen bir modelin geliştirilmesi amaçlanmıştır. Vücut ölçüleri arasında çoklu bağlantı durumu ortaya çıkmasından dolayı en küçük kareler regresyonuna alternatif olan ridge ve temel bileşenler regresyon analiz yöntemleri uygulanmış ve aynı veri seti için bu üç metot karşılaştırılmıştır. Karşılaştırma kriteri olarak belirleme katsayısı (R2), hata kareler ortalamasının karekökü (S), hata kareler ortalaması ve modellerin varyasyon katsayısı kullanılmıştır. Bu kriterlere göre, en iyi uyumu sırasıyla en küçük kareler (R20.905, S19.587), ridge (R20.898, S20.2563) ve temel bileşenler regresyon (R20,878 S22.127) metotlarının verdiği gözlenmiştir. Sonuç olarak, çoklu doğrusal bağlantı durumunda en küçük kareler metodu kullanmak yerine Ridge ve temel bileşenler regresyon yöntemlerinin kullanılmasının daha doğru olabileceği kanaatine varılmıştır.Ridge and principal component regression analysis methods are statistical analysis techniques that are used to analyze multiple regression data. In the case of Multicollinearity, although Least Squares estimates are unbiased, variances of these estimates are larger and these variances can be farther than real values. With adding a degree of bias to regression estimates, standard errors of Ridge and principal component regression are reduced. Therefore, in the event of Multicollinearity, Ridge and principal component regression methods can be used as an alternative to Least Squares method. This investigation aimed to fit a model in order to estimate carcass weight from various body measurements of 91 cyprinus fish with different ages. As Multicollinearity problems among body measurements were determined, Ridge and principal component regression methods as an alternative to Least Squares method were applied for available data, performances of these three methods for the data were compared with each other. In order to compare effectiveness of these methods, Coefficient of Determination (R2), Root of Mean Square Error (RMSE), Mean Square Error (MSE), and Coefficient of Variation as comparison criteria were used. According to these criteria, the best fit orders were observed in least squares (R20.905, S19.587), Ridge (R20.898, S20.2563) and principal component regression (R20,878 S22.127), respectively. As a result, it was concluded that, use of Ridge and principal component regression analysis methods could be truer instead of least squares method under Multicollinerity proble

An assessment of the effects of climate change on annual streamflow in rivers in Western Turkey

Global warming and its impacts are known to cause serious problems in sustainability of natural resources. In this study, change-point analysis and trend analysis were applied to climatic (temperature, precipitation, evaporation) and streamflow data for Tuzla, Gediz and Büyük Menderes rivers. Box-Jenkins technique and ARIMA model were used for trend analysis. Results showed that there were decreases in streamflow of all rivers. The paper suggests that climate change effects on streamflow could be changeable and that many factors (anthropogenic effects, geographical location, agricultural activities) should be considered. Management strategies specified regionally are required to mitigate the potential climate change effects

Effects of Prebiotic Mannanoligosaccharides (MOS) on Histology and Biochemical Blood Parameters of Gilthead Seabream, Sparus aurata

A 90-day growth trial was conducted to determine the effects of prebiotic mannanoligosaccharides (MOS) on the histology and biochemical blood parameters of the gilthead seabream (Sparus aurata). Two experimental diets were formulated to contain MOS (Bio-Mos®) levels of 0 and 2 g/kg. The fish averaging 172.11±13.19 g were reared in six octagonal net cages (763 m3). Fish were fed twice daily to apparent satiation. Individual body weight, weight gain, survival rate and feed conversion rate FCR were measured during the experiment. The treatments produced significant differences in body weight. and weight. gain (p0.05). At the end of the experimental period, biochemical blood parameters were analyzed. Blood urea level was significantly affected in the MOS group (P<0.05). No remarkable alterations in histological examinations were found. This study highlighted the positive effects of prebiotic MOS on protein efficiency and weight gain of gilthead seabream