Placental lipoprotein lipase (LPL) gene expression in a placentotrophic lizard, Pseudemoia entrecasteauxii

Viviparity (live birth) relies on a functional placenta, which is formed by cooperating maternal and embryonic tissues. In some viviparous lineages, mothers use this placenta to transport nutrients to feed developing embryos through pregnancy (placentotrophy). The Australian lizard, Pseudemoia entrecasteauxii, provides approximately 60% of the lipid for embryonic growth and metabolism to embryos across the placenta. Lipoprotein lipase (LPL) is an important enzyme in lipid transport in vertebrates. We examined patterns of LPL gene expression to identify its role in the uterus of pregnant P. entrecasteauxii. We used reverse transcription quantitative real time PCR to measure the expression of the LPL gene in the uterine tissue throughout reproduction and compared uterine LPL expression in chorioallantoic and yolk-sac placentae. Expression of the LPL gene is significantly higher in the uterus of late pregnant compared to non-pregnant and early pregnant P. entrecasteauxii, indicating a greater capacity for lipid transport towards the end of pregnancy. The period of high LPL gene expression correlates with the time that developing embryos are undergoing the greatest growth and have the highest metabolic rate. LPL gene expression is significantly higher in the uterine tissue of the yolk-sac placenta than the chorioallantoic placenta, providing the first molecular evidence that the yolk-sac placenta is the major site of lipid transport in pregnant P. entrecasteauxii.