Figure 3

Malformation rate of Mytilus galloprovincialis larvae populations in the presence of NikkomycinZ. The effect of NikkomycinZ on the development of larvae was semi-quantitatively estimated based on up to four independent test series that were microscopically evaluated at 80× magnification. The mobility of the larvae prevented an exact quantification of malformed individuals (see also supplementary material for video microscopy data). Based on the comparison of values estimated by different experimenters, the uncertainty was defined as 20% deviation. NikkomycinZ was supplied in concentrations of 0 μM (black bars, control), 5 μM (grey bars), and 10 μM (white bars) at the earliest developmental stages as indicated on the x-axis (larval age in days after fertilization) of each graph. Each test series ended on the 15th day after fertilization. a-d. Semi-quantitative estimation of morphological abnormalities observed in living individuals of the respective larvae test cultures. The abnormal phenotype rate was defined as 100% once the whole population died. Note that only the most obvious malformations (asymmetric valves, broken shells, "half-naked" individuals) were detected at the scale of binocular microscopy at 80× magnification, whereas for example undulations or tiny fractures of the larval shells were hardly visible. a. A steady increase in the abnormal phenotype rate was observed when larvae were grown in the presence of NikkomycinZ from the 2^nd day on. About three times more individuals than in the control culture were malformed on the 8^th day. b. When NikkomycinZ treatment started on the 5^th day, the fraction of the abnormal larvae also increased with time. In comparison to the control population, about 50% more individuals were affected after three days. c, d. No obvious increase in the malformation rate was observed at 80× magnification for the duration of the test in cultures treated with NikkomycinZ from the 8^th day (c) or the 12^th day (d) on.