Lipoprotein biology during induced oogenesis in the short-finned eel, Anguilla australis-hepatic target gene expression and accumulation of nutrient sources into developing oocytes

Production of good quality eggs still plagues mass propagation efforts of anguillid eels. Understanding the lipid dynamics of artificially maturing eels will inevitably benefit captive rearing practices due to the importance of lipids for egg quality. Fortnightly sampling of shortfinned eels (Anguilla australis) subjected to hypophysation for 10 weeks allowed us to gather important information relating to multiple aspects of lipid physiology. Accordingly, expected increases in gonadosomatic (from 2.20 ± 0.14 to 23.20 ± 6.01%) and hepatic somatic indices (from 0.89 ± 0.04 to 1.93 ± 0.01%), as well as oocyte diameter (from ~ 220 to ~ 700 µm) were complemented with notable increases in hepatic and ovarian vitellogenin levels at both the gene and protein levels in treated eels compared to Ringer-injected controls. A fivefold increase in hepatic expression of oestrogen receptor-alpha, but not the -beta isoform, corroborates the role for estradiol in promoting vitellogenesis. Conversely, decreases in expression of apolipoprotein b and the peroxisome proliferator-activated receptors in the liver point to a change in the role of the liver away from the neutral lipid packaging associated with previtellogenesis towards vitellogenin loading, ultimately culminating in yolk protein sequestration by the oocytes.