Molecular cloning of ESR1, BMPR1B, and FOXL2 and differential expressions depend on maternal age and size during breeding season in cultured Asian yellow pond turtle (Mauremys mutica).

The reproductive capacity (egg size and egg number) of most of oviparous animals, including the Asian yellow pond turtle (Mauremys mutica), is constrained by the maternal age and body size, but the mechanism determining the maternal reproductive ability remains unclear. To disclose how maternal age and size affect reproductive ability of M. mutica, we first identified the full-length cDNAs from estrogen receptor 1 (ESR1), bone morphogenetic protein receptor 1B (BMPR1B), and forkhead box L2 (FOXL2). The ESR1 open reading frame (ORF) was 1, 767 bp encoding 588 amino acids. For BMPR1B, the ORF was 1599 bp encoding 532 amino acids, and an ORF of 906 bp encoding 301 amino acids was identified in FOXL2. The effects of maternal age and size on the expression of ESR1, BMPR1B, and FOXL2 in the ovary, brain, and uterus showed that ESR1 expression in large females was significantly lower than that in small females in the brain, but body size did not affect ESR1 expression in the ovary. The expression of ESR1 was significantly different in the different age groups and size groups, and there was interaction detected between maternal age and body size. However, BMPR1B expression in the ovary, brain, and uterus was independent of maternal age and size. In addition, we found different FOXL2 expression patterns between the brain and uterus, while detected interaction of female age and size in the brain and ovary. Our results imply the complexity and diversity of maternal age and size in regulating the expression of genes related to reproduction. These results provide more information for the maternal effects on the reproduction-related gene expression.