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A Novel Pattern of Placental Leucine Transfer During Mid to Late Gestation in a Highly Placentotrophic Viviparous Lizard
Author(s) -
Itonaga Keisuke,
Wapstra Erik,
Jones Susan M.
Publication year - 2012
Publication title -
journal of experimental zoology part b: molecular and developmental evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.823
H-Index - 63
eISSN - 1552-5015
pISSN - 1552-5007
DOI - 10.1002/jez.b.22446
Subject(s) - biology , placenta , offspring , yolk , leucine , gestation , pregnancy , embryo , yolk sac , fetus , andrology , medicine , endocrinology , embryogenesis , nutrient , embryo transfer , amino acid , biochemistry , microbiology and biotechnology , genetics , ecology
Placentotrophy is the nourishment of embryos by resources provided via the placenta during gestation. The magnitude and timing of placental nutrient support during pregnancy are important for embryonic growth, especially in highly placentotrophic animals such as mammals. However, no study has yet investigated how placental organic nutrient support may change during pregnancy in highly placentotrophic viviparous reptiles. Amino acids are essential nutrients for embryonic growth and leucine is a common amino acid. The magnitude and timing of placental leucine transfer may affect embryonic growth and mass and, therefore, offspring phenotype. In this study, female P seudemoia entrecasteauxii , a highly placentotrophic viviparous skink, were collected throughout gestation. We injected 3 H ‐leucine into these gravid females and assessed the transfer of 3 H ‐leucine into maternal compartments (i.e., the blood and the liver), and into embryonic compartments (i.e., the embryo, the yolk, and the amniotic fluid). At either 60 or 120 min post‐injection, the radioactivity in each sample was extracted and then counted, and the transfer ratio was calculated. Our results provide direct evidence that circulating maternal leucine passes through the placenta into the embryos in this species. The relative rate of placental leucine transfer did not alter during mid to late gestation. This suggests the steady somatic growth of the embryos during mid‐late pregnancy is dependent upon the placental transfer of nutrients rather than yolk stores. This pattern of placental nutrient support may determine offspring body size at birth and, therefore, offspring fitness in P . entrecasteauxii . J. Exp. Zool. (Mol. Dev. Evol.) 318:308–315, 2012 . © 2012 Wiley Periodicals, Inc.