Quantitative comparisons of maternal transcripts related to cell division between good and poor quality eggs from artificially matured Japanese eel Anguilla japonica

The current method of artificial egg production in Japanese eel does not always yield good quality eggs, but the molecular basis for the decrease in egg quality remains unclear. In this study, we compared the levels of 74 maternal transcripts related to cell division among good quality eggs, developing poor quality eggs (i.e., those producing a viable morula embryo without hatching), and non-developing poor quality eggs (i.e., developmentally incompetent eggs) to determine the molecular characteristics of poor quality eggs produced by artificially matured Japanese eel. Only one transcript (lsm7) had a lower level in developing poor quality than in good quality eggs, with the others being present at similar levels between the two types of egg. The levels of 11 transcripts (e.g., cdc26, psma7) were lower in non-developing poor quality than in good quality eggs. These results suggest that insufficient or reduced levels of maternal mRNA related to cell division are associated with the loss of egg quality in artificially matured Japanese eel, and that maternal characteristics other than quantity may affect the developmental competence of poor quality eggs