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Carbonic anhydrase II is found in the placenta of a viviparous, matrotrophic lizard and likely facilitates embryo‐maternal CO 2 transport
Author(s) -
Van Dyke James U.,
Lindsay Laura A.,
Murphy Christopher R.,
Thompson Michael B.
Publication year - 2015
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.22621
Subject(s) - carbonic anhydrase , embryo , placenta , biology , embryogenesis , embryonic stem cell , uterus , bicarbonate , biochemistry , chemistry , microbiology and biotechnology , fetus , enzyme , endocrinology , pregnancy , genetics , gene
The evolution of viviparity requires the development of mechanisms that facilitate transport of respiratory gases between mother and developing embryo. Of particular importance is maternal excretion of embryonic carbon dioxide (CO 2 ), which increases as the embryo grows in size during development. The carbonic anhydrases are a family of enzymes that convert CO 2 to bicarbonate for transport throughout the cardiovascular system and which may also be important for CO 2 transport from embryo to mother. We used immunohistochemistry to localize carbonic anhydrase II in the placental tissues of a viviparous and highly placentotrophic lizard, Pseudemoia entrecasteauxii . Carbonic anhydrase II is localized in the uterine component of the paraplacentome, presumably to facilitate transport of embryonic CO 2 to the mother. Carbonic anhydrase II is also localized in both the uterine and embryonic components of the placentome, a region heavily involved in placental nutrient transport rather than respiratory gas exchange. In contrast, carbonic anhydrase II is not present in the uterine or embryonic components of the omphaloplacenta, another region responsible for nutrient transport. While carbonic anhydrase II in the paraplacentomal uterus is likely to be responsible for embryo‐maternal CO 2 transport, the distribution of carbonic anhydrase II throughout the placentome indicates a different function. Instead of transporting embryonic CO 2 , placentomal carbonic anhydrase II appears to be responsible for transporting CO 2 produced by energetically expensive nutrient transport mechanisms in both the uterus and the embryo, which implies that the mechanisms of nutrient transport in the omphaloplacenta may not be as energetically expensive. J. Exp. Zool. (Mol. Dev. Evol.) 324B: 636–646, 2015 . © 2015 Wiley Periodicals, Inc.