" Hypoxia caused by eutrophication is the major pressing problems in aquatic ecosystems worldwide and as well as considerable economic losses to fisheries. These long standing problems will be exacerbate in the coming years due to global warming, particularly in developing countries where construction of waste treatment facilities lags well behind everincreasing population demands. Hypoxia has been shown to be an endocrine disruptor and can impair reproduction and affect development of fish and higher vertebrates. Chronic exposure to hypoxia could impair reproduction and sexual development of fish through disruption of sex hormones and their receptors along the hypothalamic pituitary gonadal (HPG) axis.
Recent studies showed that many endocrine disruptors may also cause transgenerational effects. Offspring of future generations are thus affected even though they themselves have not been directly exposed. Using the marine medaka (Oryzias melastigma) as a study model, this research aims to test the hypothesis that exposure to hypoxia can cause transgenerational effects in fish, and we further hypothesize that any observed transgenerational effects on immunomodulation, maternal complement components and also on modulation of steroidogenesis in HPG axis. Nearly 2000 fish were exposed to hypoxic (1.5 mg L-1) and normoxic (6.0 mg L-1) conditions for 30 days and eggs (F1 generation) were then collected and reared under hypoxic or normoxic conditions.
For chronic exposure the fish was exposed for 250 days under hypoxia and analysed for immune associated parameters and steroidogenesis genes. Obtained result shows that majority of the immune related parameters and steroidogenesis genes in HPG axis are modulated. This study highlights the interesting findings from the F0/F1/F2 generations, with a focus on the changes in hypoxia-responsive mRNAs and protein in both steroidogenesis and immunomodulatory pathways."