Abstract
The presence of annexin II (Ann-II) during the initial stages of bovine embryo development and the regulation of Ann-II expression by retinol and insulin-like growth factor I (IGF-I) were studied. Bovine embryos at different stages of development were produced in vitro on Synthetic Oviductal Fluid (SOF) medium (control group), SOF supplemented with retinol (retinol group; 0.1ng/ml), or IGF-I (IGF-I group; 10ng/ml). The embryos were processed for mRNA extraction, cDNA production and polymerase chain reaction (PCR) using Ann-II-specific oligonucleotides. Ann-II was detected in all stages of early embryo development, except for the 16-cell stage. The blastocyst rates were significantly higher (P<0.05) in the group supplemented with retinol (37.8%, 45/119) during in vitro embryo culture (IVC) than in those cultured in SOF (20.5%, 24/117) or SOF with IGF-I (25.8%, 24/93). Semiquantitative analysis of Ann-II expression in embryos produced in medium supplemented with IGF-I or retinol revealed a lower expression of this gene when compared with embryos cultured in SOF (P<0.05). The Ann-II expression was not different in embryos cultured in the presence of retinol and IGF-I. The presence of retinol increased the production of embryos in vitro by decreasing the expression of Ann-II in early-stage of bovine embryo.
Highlights
In vitro production of bovine embryos has been one of the most widely used biotechnologies in the last decade and represents one of the main tools for the multiplication of genetic material
No expression of annexin II (Ann-II) was observed in 16-cell embryos, while the transcription of this gene was reinitiated in the 32-cell stage
The presence of retinol during embryo development led to a significant increase (P
Summary
In vitro production of bovine embryos has been one of the most widely used biotechnologies in the last decade and represents one of the main tools for the multiplication of genetic material. Cleavage and embryo development up to the blastocyst stage have been reported to be approximately 92, 77 and 40%, respectively (Greve et al, 1993; Carolan et al, 1995; Castilho et al, 2007), and continue at these levels, with wide variation being observed due to the use of substances of unknown composition such as estrous cow serum (ECS) or fetal bovine serum (FBS). Pregnancy outcomes are still below the rates obtained with the traditional embryo transfer system. The embryonic genome is activated during the fourth cycle of cell division, and a large number of both in vivo and in vitro embryos stop their development during this stage. Certain cell division-related genes are involved in this 8-16-cell block
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