# Morphological and Molecular Alterations Induced by Lead in Embryos and Larvae of _[PERSON]_
## 3 Results
### Gene Expression  
Quantitative RT-PCR showed that Pb exposure induced the modulation of all analysed genes. Metallothione, mtf--After exposure to the low concentration of Pb, the gene was significantly upregulated compared to the control at all exposure times (* \(p\) < 0.05; Figure 5a). A similar pattern was observed in the high concentration group when the expression further increased (***** \(p\) < 0.0001; Figure 1a), reaching a peak after 96 h of exposure (***** \(p\) < 0.0001; Figure 5a). \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline  & & \multicolumn{3}{c}{**CTRL**} & \multicolumn{3}{c}{**2.5 ug/L**} & \multicolumn{3}{c}{**5 ug/L**} \\ \cline{2-10}  & & **48 h** & **96 h** & **144 h** & **48 h** & **96 h** & **144 h** & **48 h** & **96 h** & **144 h** \\ \cline{2-10}  & Spinal deformity & 0 & 0 & 0 & 30 (* * *) & 50 (* ***) & 60 (* ***) & 90 (ab ***) & 90 (a ***)(b * * ) & 100 (* ***)(b * * ) \\ \cline{2-10}  & Tail deformity & 0 & 0 & 0 & 20 (* * *) & 50 (* ***) & 50 (* ***) & 90 (ab ***) & 90 (a ***)(b * * ) & 100 (ab ***) \\ \cline{2-10}  & Yolk sac & 0 & 0 & 0 & 30 (* * *) & 60 (* ***) & 0 & 40 (* ***) & 70 (* ***) \\ \cline{2-10}  & Pericardial edema & 0 & 0 & 0 & 0 & 0 & 0 & 20 (*?) & 50 (ab ***) & 60 (ab ***) \\ \cline{2-10}  & Uninflated swim bladder & 0 & 0 & 0 & 0 & 0 & 60(* ***) & 0 & 0 & 80 (* ***) \\ \hline \multicolumn{10}{c}{Cumulative deformity} & 0 & 0 & 0 & 60 (* ***) & 90 (* ***) & 90 (* ***) & 90 (* ***)(b * * ) & 90 (* ***) & 100 (* ***) \\ \hline \multicolumn{10}{c}{Score value} & 0 & 0 & 0 & 12 (* * *) & 35 (* ***) & 58 (* ***) & 58 (ab ***) & 74 (ab ***) & 144 (ab ***) \\ \hline \hline \end{tabular}  
* a = significant difference between treated group and control group; b = significance difference between high concentration and low concentration group;
* \(p\) < 0.05; **_p_ < 0.002; ***_p_ < 0.001; ***_p_ < 0.0001.  
\end{table} 
Table 1: Frequency (%), cumulative deformity (%) and severity of morphological abnormalities in zebrafish embryos and larvae (n = 90) exposed to 2.5 and 5 ug/L of Pb for 48, 96 and 144 h.  
Figure 3: Gross morphology of zebrafish embryos and larvae after exposure to 2.5 \(\upmu\)g/L of Pb: (**a,b**) note the appearance of spinal and tail deformity after 48 h of exposure to Pb; (**c**) dorsal and (**d**) frontal view of spinal deformity after 96 h of exposure to Pb. Note the swelling of the yolk sac; (**e,f**) after 144 h of exposure to Pb, the severity of spinal and tail deformity increases. Also, the swelling of the yolk sac is evident along with the uninflated swim bladder. Sd = spinal deformity, td = tail deformity, sys = swelling of the yolk sac, usb = uninflated swim bladder, e = eye, m = mouth, o = otolith, h = heart, ys = yolk sac. All scale bars = 200 \(\upmu\)m.  
Superoxide dismutase 1, _sol1_--Pb exposure resulted in a significant increase of _sol1_ expression in both concentration groups at all exposure time, compared to the control, also showing a dose-dependent trend (**_p_ < 0.01; Figure 5b). Lactate dehydrogenase, ldh_--A significant upregulation of _ldh_ expression was recorded in both concentration groups compared to the control (****_p_ < 0.0001; Figure 5c). The increase in gene expression was higher in the high concentration group, showing a statistically significant difference even compared to the low concentration group (****_p_ < 0.0001; Figure 5c). Figure 4: Gross morphology of zebrafish embryos and larvae after exposure to 5 \(\upmu\)g/L of Pb: (**a,b**) spinal and tail deformity are frequently detected after 48 h of exposure. Note the appearance of pericardial edema; (**c,d**) after 96 h of exposure, both yolk sac swelling and pericardial edema are commonly observed; (**e–**) all larvae show spinal and tail deformity after 144 h of exposure. Note pericardial edema, yolk sac swelling, and uninflated swim bladder. Sd = spinal deformity, td = tail deformity, pe = pericardial edema, sys = swelling of the yolk sac, usb = uninflated swim bladder.