Hormone effects on the scale, swim bladder and fins differentiation in Juvenile zebrafish

Abstract

Bioactive compounds are critical regulator of general development and physiological functioning in zebrafish embryos. We have experimentally raised triiodothyronine (T3) content of zebra fish eggs by immersion process with water. Exogenous thyroid hormone (TH) reportedly induces early stages of the zebrafish and observed the development of pectoral fin after 72 hpf, 5dpf and 7 dpf, which shows the differences between control and T3 treatment. We also found the comparable difference in caudal fin length after 14 dpf, which increased after 14 dpf T3 immersion than the control. We observed eyes differences after 3 dpf but no significant differences was found (P>0.05) after 10 pdf. The hormone treatment significantly accelerated the differentiation and inflation of swim bladder. The inflation of swim bladder become higher in hormone treated group than in control after 5 days of treatment whereas it changes after 7 dpf. At the same time, we observed the color pigmentation in the body of hormone treated larvae while no significant color observed in control larvae. The pattern of larval mortality was an increase in larval death rate near the start of the 96 hpf. Treatment promoted survival significantly higher survival during the experiment (P<0.05). We interpret this with mean that there was a statistically significant relationship between untreated control and treatment. The possible reason of scale formation in the body of thyroid hormone treated larvae. This study extends the evolutionary relatedness of fish fin growth, eyes, scales, swim bladder and suggest that TH is required to complete the life cycle of a zebra fish.