Effects of UV exposure on developing zebrafish embryos

• Main Author: Miguel, Carlo D. Yap
• Format: text
• Language: English
• Published: Animo Repository 2016
• Subjects: Zebra danio > Southeast Asia; Biology
• Online Access: https://animorepository.dlsu.edu.ph/etd_bachelors/3013
• Institution: De La Salle University

Zebrafish (Danio rerio), a tropical fish native to Southeast Asia, is known to have a competent photorepair system. This study strived to determine the effects of low-intensity ultraviolet light exposure on the growth and development of zebrafish embryos, and to correlate that with exposure age and time. It was done by inducing commercially available zebrafishes to spawn, collecting the egg and subjecting them to different treatments. The embryos were exposed to a 485 nm ultraviolet light at different developmental stages: 0, 24, and 48 hours-post-fertilization, for different lengths of time: 10, 15, and 30 minutes, using two 5-watt UV lamps. Upon hatching, the surviving larvae were observed under a microscope where the gut sizes and body lengths were measured, and any deformities were noted then compared against an untreated control group. The mortality and hatching rates were also tallied. The control group had the lowest mortality, next is the 0hpf-30min treatment, whereas the 48hpf-30min treatment had the highest mortality. The cause of the higher mortality in older embryos may be due to damage done on differentiated cells that could no longer be repaired or replaced. It is also possible that the enzymes that break down the chorion had been affected by the treatment and the larvae died within the egg either due to exhaustion or suffocation. Among the abnormalities observed were delayed hatching, bent tails, pericardial edema, and unusual pigmentations around the gut. Statistically, although there was a significant difference between the mortality proportions of the control and 48hpf treatments, there was no significant difference in the gut sizes and body lengths throughout all the treatments as well as the control.