Hypoxia Causes Transgenerational Impairment of Ovarian Development and Hatching Success in Fish

Hypoxia is a pressing environmental
problem in both marine and
freshwater ecosystems globally, and this problem will be further exacerbated
by global warming in the coming decades. Recently, we reported that
hypoxia can cause transgenerational impairment of sperm quality and
quantity in fish (in F0, F1, and F2 generations) through DNA methylome
modifications. Here, we provide evidence that female fish (Oryzias melastigma) exposed to hypoxia exhibit reproductive
impairments (follicle atresia and retarded oocyte development), leading
to a drastic reduction in hatching success in the F2 generation of
the transgenerational group, although they have never been exposed
to hypoxia. Further analyses show that the observed transgenerational
impairments in ovarian functions are related to changes in the DNA
methylation and expression pattern of two gene clusters that are closely
associated with stress-induced cell cycle arrest and cell apoptosis.
The observed epigenetic and transgenerational alterations suggest
that hypoxia may pose a significant threat to the sustainability of
natural fish populations.