GENETIC-REGULATION OF PLACENTAL FUNCTION - A QUANTITATIVE IN-SITU HYBRIDIZATION STUDY OF CALCIUM-BINDING PROTEIN (CALBINDIN-D-9K) AND CALCIUM-ATPASE MESSENGER-RNAS IN SHEEP PLACENTA
G. Morgan et al., GENETIC-REGULATION OF PLACENTAL FUNCTION - A QUANTITATIVE IN-SITU HYBRIDIZATION STUDY OF CALCIUM-BINDING PROTEIN (CALBINDIN-D-9K) AND CALCIUM-ATPASE MESSENGER-RNAS IN SHEEP PLACENTA, Placenta, 18(2-3), 1997, pp. 211-218
The calcium requirement of the ovine fetus increases progressively thr
oughout pregnancy. The 9-kDa calcium binding protein (calbindin-D-9h;
9CBP) is considered to be a reliable marker for epithelia mediating ca
lcium transport. This quantitative in situ hybridization study shows t
hat the levels of 9CBP mRNA show a pregnancy stage-related increase wh
ich correlates with fetal calcium demand only in maternal endometrial
gland and fetal interplacentomal trophoblast epithelia. Levels of 9CBP
mRNA in the placentome, which has by far the greater area of maternof
etal contact, show no changes during pregnancy. mRNA for the CaATPase
enzyme, a second requirement for calcium transport, is shown to be pre
sent in epithelia in interplacentomal and placentomal regions but show
s no change in concentration as pregnancy progresses. Results with the
9CBP and CaATPase mRNAs confirm our recent immunocytochemical results
with ruminant placenta and indicate the basis for a cellular calcium
transport system analogous to that in the enterocyte. The interplacent
omal trophoblast system appears to be eminently suitable for investiga
tions of details of the cellular mechanism and control of epithelial c
alcium transport. (C) 1997 W. B. Saunders Company Ltd.