Direct Evidence for Mother-to-Embryo Transfer of Nutrients in the Livebearing Fish<i>Gambusia geiseri</i>

Abstract

We present direct experimental evidence of maternal-to-embryo nutrient transfer in largespring gambusia, a species in which embryonic development was believed to depend solely on nutrients and energy sequestered in the egg prior to fertilization. Thirteen pregnant females were injected with tritiated leucine, and developing embryos of those individuals were assayed for radioactivity two hours postinjection. In eight females, one to all embryos in the developing brood showed significant uptake of labeled leucine. This finding suggests that matrotrophy may be an important maternal investment strategy for this species.