Expression of methylation pathway enzymes in bovine oocytes and preimplantation embryos

153EXPRESSION OF TGF-BETA I AND TYPE I AND TYPE II OF TGF-BETA RECEPTORS IN BOVINE EMBRYOS

Reproduction Fertility and Development ◽

10.1071/rdv16n1ab153 ◽

2004 ◽

Vol 16 (2) ◽

pp. 198

Author(s):

B.K. Kim ◽

H.J. Chung ◽

B.C. Yang ◽

D.H. Kim ◽

J.H. Woo ◽

...

Keyword(s):

Embryo Development ◽

Expression Patterns ◽

Blastocyst Stage ◽

Preimplantation Embryos ◽

Type I ◽

Bovine Embryo ◽

Type Ii ◽

Bovine Embryos ◽

Mrna And Protein Expression ◽

Bovine Oocytes

Although the effects of TGFβ1, as an important factor in the mice embryo development have been reported, little information relevant to this subject is known in the bovine embryo. The objectives of this study were to investigate the presence and expression patterns of TGFβ1 and TGFβ1 receptors, types I and II, in unfertilized oocytes and fertilized bovine embryos in normal and NT embryo development. We postulated that TGFβ1 may have a beneficial effect on the preimplantation embryo and show different expression patterns at different stages of bovine embryo development. Immature bovine oocytes were aspirated from follicles of ovaries obtained from a local abattoir and they were cultured for up to 24h and fertilized in vitro. Reverse transcription-polymerase chain reaction (RT-PCR) and immunocytochemistry were used to investigate the presence of TGFβ1 and type I and type II of TGFβ1 receptors (the essential components of the TGFβ1 signaling pathway) in unfertilized oocytes and preimplantation embryos. Also, mRNA and protein expression patterns of TGFβ1 and their receptors at various stages of embryos were examined. It was found that both receptors, as well as TGFβ1, were present in the unfertilized bovine oocytes, indicating that TGFβ1 is a maternally expressed protein. Although the type I TGFβ1 receptor was present at the morulae and blastocyst stages, the type II TGFβ1 receptor was not present at both stages. It was also confirmed that the expression level of TGFβ1 was high at the 8-cell stage, and mRNA and protein expression patterns of TGFβ1 and their receptors were not coincident. Interestingly, TGFβ1 protein was not detected at blastocyst stage of embryos, whereas the mRNA expression level was high at this stage. The results of this experiment indicate that TGFβ1 protein may be needed by embryos after the blastocyst stage and may be expressed in hatched embryos for implantation. These findings support the hypothesis that there may be an interaction between the TGFβ1 and TGFβ1 receptors in the unfertilized oocytes and preimplantation embryos, and that TGFβ1 signaling may be important for the development of the oocytes and the preimplantation embryos.

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Alkaline phosphatase activity in bovine oocytes and preimplantation embryos as affected by removal of the zona pellucida and culture medium constituents

Reproduction Fertility and Development ◽

10.1071/rd03025 ◽

2003 ◽

Vol 15 (5) ◽

pp. 285 ◽

Cited By ~ 3

Author(s):

J. L. Edwards ◽

A. M. Powell ◽

C. E. Rexroad Jr

Keyword(s):

Alkaline Phosphatase ◽

Phosphatase Activity ◽

Alkaline Phosphatase Activity ◽

Zona Pellucida ◽

Bovine Serum ◽

Culture Medium ◽

Preimplantation Embryos ◽

Perivitelline Space ◽

Mechanical Removal ◽

Bovine Oocytes

The aims of the present study were: (1) to characterize alkaline phosphatase (AP) activity in bovine oocytes and embryos with intact or removed zona pellucida (ZP); and (2) to evaluate the effect of culture medium constituents on AP activity. Alkaline phosphatase activity in non-matured and matured oocytes was most evident nearest the plasma membrane and perivitelline space. In more than 90% of two- to 16-cell embryos, AP activity was observed in the perivitelline space and at blastomere contacts. In blastocysts, AP activity was localized to the trophectoderm. Only after immunodissection was AP activity detected in the inner cell mass. Removal of the ZP by pronase or mechanical means reduced AP activity. Alkaline phosphatase activity was detected in evacuated ZP after mechanical removal. Specific constituents comprising the embryo culture medium altered AP activity. Alkaline phosphatase activity was reduced in eight- to 16-cell embryos and evacuated ZP cultured in CR1aa + 0.4% bovine serum albumin compared with embryos cultured in CR1aa alone or embryos co-cultured on a monolayer of Buffalo rat liver cells in the presence of 10% fetal bovine serum. The presence of AP activity at blastomere contacts and in evacuated ZP limits its usefulness as a marker for the differentiation of embryonic cells comprising the early cleavage-stage embryo.

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