Meeting Abstract
Maternal investments in eggs affect offspring growth and development, but the mechanisms of these effects are not always clear. Melatonin is a hormone with wide ranging effects on phenotypes, and is found in egg yolks. We evaluated the influence of yolk-derived melatonin in early chicken (Gallus gallus) embryos. We assigned forty eggs to one of four treatment groups (melatonin, Luzindole (a melatonin antagonist), saline vehicle, or a melatonin and Luzindole mix), and injected eggs with 100 ul of their respective treatment before incubation. After approximately two days of incubation we opened eggs, staged embryos using Hamilton-Hamburg stages, and measured embryonic heart rate. Embryos from eggs treated with melatonin had significantly lower heart rates and faster developmental rates than embryos from vehicle control eggs. Likewise, Luzindole-treated eggs produced embryos with significantly lower heart rates and faster developmental rates than embryos from vehicle control eggs. Embryos from a mix of melatonin and Luzindole had heart rates and developmental rates that were similar to the embryos from the vehicle controls. We hypothesize that embryos with higher maternal melatonin in their eggs may grow faster and more efficiently than embryos in eggs with lower melatonin levels. These results suggest that maternal melatonin may influence embryonic developmental trajectories, and could ultimately affect offspring survival and fitness, which should be further evaluated.
