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Expression of 3β‐hydroxysteroid dehydrogenase in early bovine embryo development
Author(s) -
Chiappe M.E.,
Lattanzi M.L.,
ColmanLerner A.A.,
Barañao J.L.,
Saragüeta P.
Publication year - 2002
Publication title -
molecular reproduction and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.745
H-Index - 105
eISSN - 1098-2795
pISSN - 1040-452X
DOI - 10.1002/mrd.1140
Subject(s) - biology , blastocyst , embryo , oocyte , embryogenesis , enzyme , embryonic stem cell , in vitro , pregnenolone , microbiology and biotechnology , steroid , andrology , biochemistry , hormone , gene , medicine
We analyzed the presence of 3β‐Hydroxysteroid Dehydrogenase/Δ 5→4 ‐isomerase enzyme (3β‐HSD) activity, a key enzyme of the steroid metabolic pathway, the mRNA of this enzyme, and the steroid metabolism in in vitro produced bovine embryos. 3β‐HSD activity was detected in in vitro matured oocytes (74.4 ± 1.4%), 1‐cell (72.9 ± 6.1%), 2‐cell (61.8 ± 7.4%), 8‐cell (50 ± 5%), morulae (50.8 ± 2.6%), blastocysts (94.4 ± 3%), and hatched blastocysts (100 ± 0%) meanwhile the 4‐cell stage showed a significant reduction (16.7 ± 4.7%). When total embryonic RNA of different stages was subjected to RT‐PCR assays, the mRNA of 3β‐HSD was found to be present in all developmental stages of in vitro produced bovine embryos, from the oocyte to the blastocyst, with a marked decrease at the 4‐cell stage. To determine whether the temporal pattern of enzyme activity was dependent on the maternal to zygotic transition, embryos were incubated in the presence of a transcription inhibitor, α‐amanitin. The reappearance of the enzyme activity after the 4‐cell stage was blocked in α‐amanitin treated embryos, indicating the requirement of embryonic transcription. On the other hand, the embryonic steroid metabolism was tested by incubating blastocyst with tritiated pregnenolone. Analysis of the metabolites by TLC indicated the production of a compound with a mobility identical to progesterone. These results described the expression of the 3β‐HSD and the activity of this metabolic enzyme in bovine oocytes and preimplantation embryos, suggesting that steroids may act as autocrine effectors on preimplantation embryo development. Mol. Reprod. Dev. 61: 135–141, 2002. © 2002 Wiley‐Liss, Inc.