Reproductive Technologies and Genomic Selection in Cattle

The recent development of genomic selection induces dramatic changes in the way genetic selection schemes are to be conducted. This review describes the new context and corresponding needs for genomic based selection schemes and how reproductive technologies can be used to meet those needs. Information brought by reproductive physiology will provide new markers and new improved phenotypes that will increase the efficiency of selection schemes for reproductive traits. In this context, the value of the reproductive techniques including assisted embryo based reproductive technologies (Multiple Ovaluation Embryo Transfer and Ovum pick up associated to in vitro Fertilization) is also revisited. The interest of embryo typing is discussed. The recent results obtained with this emerging technology which are compatible with the use of the last generation of chips for genotype analysis may lead to very promising applications for the breeding industry. The combined use of several embryo based reproductive technologies will probably be more important in the near future to satisfy the needs of genomic selection for increasing the number of candidates and to preserve at the same time genetic variability

In vitro maturation of oocytes alters gene expression and signaling pathways in bovine cumulus cells

Chantier qualité GAIn vitro maturation (IVM) of immature oocytes is widely used in assisted reproduction technologies in cattle, and is increasingly used to treat human infertility. The development competence of IVM oocytes, however, is lower than preovulatory, in vivo-matured oocytes. During maturation, cumulus cells (CC) are metabolically coupled with an oocyte and support the acquisition of its developmental potential. Our objective was to identify genes and pathways that were affected by IVM in bovine CC. Microarray transcriptomic analysis of CC enclosing in vitro- or in vivo-mature oocytes revealed 472 differentially expressed genes, including 28% related to apoptosis, correlating with twofold higher cell death after IVM than in vivo, as detected by TUNEL. Genes overexpressed after IVM were significantly enriched in functions involved in cell movement, focal adhesion, extracellular matrix function, and TGF-beta signaling, whereas under-expressed genes were enriched in regulating gene expression, energy metabolism, stress response, and MAP kinases pathway functions. Differential expression of 15 genes, including PAG11 (increased) and TXNIP (decreased), which were never detected in CC before, was validated by real-time RT-PCR. Moreover, protein quantification confirmed the lower abundance of glutathione S-transferase A1 and prostaglandin G/H synthase 2, and the higher abundance of hyaluronan synthase 2 and SMAD4, a member of TGF-beta pathway, in CC after IVM. Phosphorylation levels of SMAD2, MAPK3/1, and MAPK14, but not MAPK8, were higher after IVM that in vivo. In conclusion, IVM provokes the hyper-activation of TGF-beta and MAPK signaling components, modifies gene expression, leads to increased apoptosis in CC, and thus affects oocyte quality

Bovine oocyte quality: from phenotype to transcriptome

International audienc

An integrated approach to bovine oocyte quality: from phenotype to genes

In cattle, early embryonic failure plays a major role in the limitation of reproductive performance and is influenced by genetic effects. Suboptimal oocyte quality, including an inadequate store of maternal factors, is suspected to contribute to this phenomenon. In the present study, 13 Montbeliarde cows were phenotyped on oocyte quality, based on their ability to produce viable embryos after in vitro maturation, fertilisation and culture for 7 days. This discriminated two groups of animals, exhibiting developmental rates below 18.8% or above 40.9% (relative to cleaved embryos). Using microarrays, transcriptomic profiles were compared between oocytes collected in vivo from these two groups of animals. The difference in oocyte development potential was associated with changes in transcripts from 60 genes in immature oocytes and 135 genes in mature oocytes (following Bonferroni 5% correction). Of these, 16 and 32 genes were located in previously identified fertility quantitative trait loci. A subset of differential genes was investigated on distinct samples by reverse transcription-quantitative polymerase chain reaction. For SLC25A16, PPP1R14C, ROBO1, AMDHD1 and MEAF6 transcripts, differential expression was confirmed between high and low oocyte potential animals. Further sequencing and searches for polymorphisms will pave the way for implementing their use in genomic selection