Maternal housekeeping proteins translated during bovine oocyte maturation and early embryo development

Abstract

Protein synthesis from maternal mRNA is needed to sustain oocyte maturation and embryo development prior to the maternal-embryonic transition (MET). Therefore, proteins that are expressed throughout this time are important and may be considered as maternal housekeeping proteins (MHKP). Our objectives were first, identify the translated protein patterns of bovine embryo development and secondly, determine the MHKP. Proteins synthesized during oocyte maturation and embryo development (2, 4 and 8-cell stages) were labeled using [S(35)]-Met and [S(35)]-Cys, and visualized by 2-DE. Embryos were cultured with alpha-amanitine to inhibit new transcription. Only 46 proteins were present throughout all stages. Ten spots were identified by MALDI-TOF and MS/MS: HSC71; HSP70; CypA; UCH-L1; GSTM5; Cct5; E-FABP; 2,3-BPGM, ubiquitin-conjugating enzyme E2D3; and beta-actin/gamma-actin. A new method called in silico protein identification confirmation was developed using EST databases. This method is a promising approach for use in rare tissue or from species with an incomplete protein database. This study has revealed that the translated protein patterns show a transition that brings the embryo to the MET. The needs in translated proteins between oocyte maturation and embryo development are different. In summary, this study represents the bases for future proteomics studies on bovine oocytes and embryos.

The quiet embryo hypothesis: Molecular characteristics favoring viability

“…Future developments in mass spectrometry may allow the proteome of a single zygote to be characterized (Massicotte et al, 2006), thus allowing this hypothesis to be tested directly. However, the relative abundance of DNA and RNA damage surveillance and repair/degradation complexes can be investigated using existing technologies.…”

RNA Processing During Early Embryogenesis: Managing Storage, Utilisation and Destruction

“…In the bovine, the EGA occurs when the embryonic RNA content are the lowest (Gilbert et al 2009). The depletion of the maternal RNA content is massive and it is not paralleled by the amount of newly synthesized proteins during these developmental stages as determined by proteomic analysis (Massicotte et al 2006). In addition, the abundance of ribosomal RNAs (rRNAs) during the pre-EGA stages show atypical profiles with low levels of 28S, the large rRNA component of the 60S ribosomal subunit, which may be indicative of lower translational potential in these early developmental stages (Gilbert et al 2009).…”

Opportunities and challenges in applying genomics to the study of oogenesis and folliculogenesis in farm animals

“…The study of protein profiles during oocyte maturation or early embryogenesis in the bovine (Coenen et al 2004, Bhojwani et al 2006, Massicotte et al 2006 indicates hundreds of new products before and after fertilisation as well as many proteins that disappear. Since there is no transcription following the germinal vesicle break down and possibly a very low level after fertilisation (Memili & First 1999), these changes must rely on fine regulation of hundreds of transcripts by a mechanism other than transcription.…”