2.4. Assessment of TCS-DT-induced cardiotoxicityTo evaluate the effects of TCS-DT exposure on larval heartdevelopment, we assessed cardiac malformations, including heartrate, ejection fraction and SV-BA distance.(i) Heart rate and ejection fraction measurementsSubsequent to exposure to TCS-DT from 6 hpf, we observed the48-hpf embryos using a stereoscope coupled to a digital camera(SZX16, Olympus, Japan) to record video images for determinationof heartbeat rate for 2 min at 28.5 C (Li et al., 2019). We used areasubtraction to estimate ejection fraction according to Matrone andcoworkers’ report (Matrone et al., 2014). Briefly, the ventricularcontraction area was substracted from the diastolic area of theheart, which were expressed as a percentage of the diastolic area.(ii) SV-BA distance measurement