# The Influence of Silver Nanoparticle Form on the Toxicity in Freshwater Mussels
## 3 Results
Based on nAg with similar SA, AChE activity was not affected by spherical and prismatic nAg of similar SA, but a significant effect (\(p\) = 0.05) was observed for /D, suggesting that changes in the /D of AChE was influenced by other factor(s) than solely SA (such as form or reactivity). In the attempt to gain a global understanding of the influence of Ag forms on mussel tissues, a discriminant function and decision tree analysis were performed (Figure 5A,B). The analysis revealed that Ag forms produce characteristic effects based on the biomarkers examined in this study. Discriminant function analysis revealed that most forms of Ag were somewhat discriminated between groups but with a mean classification performance of 35% only. The following endpoints explained most of the variance (93%): AChE, /D, viscosity, lipids, labile Zn and viscosity. If we take these and perform a decision tree analysis, the following classification rules are obtained: if viscosity >1.1-fold of controls then it is a cubic nAg; otherwise, if protein aggregation <0.85 of controls then it is a cubic nAg; otherwise, if protein aggregation >1.2-fold of controls then it is a prismatic nAg; otherwise, if the /D of AChE < controls then sphere nAg otherwise it is dissolved Ag. Hence, cubic nAg is a compound producing a stronger increase in viscosity than the other forms of Ag in mussels. A prismatic form of nAg leads to more important changes in protein aggregation, while spheric nAg decreases the /D of AChE activity with low changes in protein aggregation and  
Figure 3: Oxidative stress in mussels exposed to various nAg forms. Mussel tissue homogenates were prepared for viscosity (**A**), arachid cyclooxygenaseasive activity (**B**) and lipid peroxidation (**C**). The data represent the mean with the standard error. The star symbol * indicates significance from controls. viscosity. The dissolved fraction of Ag produces only slight changes in lipids and protein aggregation. Figure 4: Change in AChE activity in mussels exposed to the various Ag forms. Mussel whole tissue homogenate fractions were isolated and analyzed for AChE activity (**A**) and the fractal dimension of AChE (**B**). The data represent the mean with the standard error. The star symbol * indicates significant differences from controls. Figure 5: Discriminant function and decision tree analysis of biomarker data. The discriminant function analysis (**A**) was performed to distinguish the response patterns between the forms of Ag and the decision tree analysis was performed to determine how the specific effects could discriminate between forms. The total explained variance was 95%, with a mean classification accuracy of 45%. The mean score values are shown for controls, dissolved (Diss) and the three forms of nAg: cubes, spheres and prisms. The decision tree analysis (**B**) goes as follows: start as cubes; if viscosity >1.1-fold of controls then cubic nAg; otherwise, if protein aggregation <0.85 of controls then cube; otherwise, if protein aggregation >1.2-fold of controls then prismatic nAg; otherwise, if /D of AChE < controls then sphere otherwise it is dissolved.