A small set of extra-embryonic genes defines a new landmark for bovine embryo staging

Abstract

Axis specification in mouse is determined by a sequence of reciprocal interactions between embryonic and extra-embryonic tissues so that a few extra-embryonic genes appear as 'patterning' the embryo. Considering these interactions as essential, but lacking in most mammals the genetically driven approaches used in mouse and the corresponding patterning mutants, we examined whether a molecular signature originating from extra-embryonic tissues could relate to the developmental stage of the embryo proper and predict it. To this end, we have profiled bovine extra-embryonic tissues at peri-implantation stages, when gastrulation and early neurulation occur, and analysed the subsequent expression profiles through the use of predictive methods as previously reported for tumour classification. A set of six genes (CALM1, CPA3, CITED1, DLD, HNRNPDL, and TGFB3), half of which had not been previously associated with any extra-embryonic feature, appeared significantly discriminative and mainly dependent on embryonic tissues for its faithful expression. The predictive value of this set of genes for gastrulation and early neurulation stages, as assessed on naive samples, was remarkably high (93%). In silico connected to the bovine orthologues of the mouse patterning genes, this gene set is proposed as a new trait for embryo staging. As such, this will allow saving the bovine embryo proper for molecular or cellular studies. To us, it offers as well new perspectives for developmental phenotyping and modelling of embryonic/extra-embryonic co-differentiation.

Energy and lipid metabolism gene expression of D18 embryos in dairy cows is related to dam physiological status

“…The morphological and molecular staging of the embryonic discs (n ϭ 23) revealed similar proportions of the expected D18 gastrulating stages in the three groups of females (5/9 in GH, 4/7 in ELC, and 3/7 in LLC), i.e., stages that display an early or a late primitive streak as described in Degrelle et al (21). In each group, however, few embryonic discs appeared younger than expected at D18, since a posterior pole instead of a streak was visualized by the Brachyury labeling ( Table 4).…”

“…Younger discs harboring no streak but a posterior pole gastrulated properly but were delayed, whereas abnormal ones were called "Ab" when the gastrulating pattern was atypical. These stages were determined on the discs or on the extraembryonic tissue (EET), as detailed in Degrelle et al (20,21). UD, undetermined; TV, trophoblastic vesicles.…”

“…The genes classically used to follow these stages are Oct-4 or Nodal for pregastrulating stages [D7-D14 (18,50)] and Brachyury for gastrulating ones [D15-D18 (20,34)]. Alternatively an extraembryonic gene set may also be used to define these stages (21).…”

Maternal-embryo interaction leading up to the initiation of implantation of pregnancy in cattle

“…However, data on gene expression during the post-hatching embryonic stages in cattle are sparse and, apart from a few exceptions, typically deal with candidate genes rather than being global in nature (Ushizawa et al, 2004;Hue et al, 2007;Degrelle et al, 2011). Surprisingly, the biochemical and molecular aspects of conceptus/endometrial interactions and blastocyst growth and conceptus development during early pregnancy are not well defined.…”

Association between BMP4 gene polymorphism and in vitro embryo production traits in Gyr cows

“…Moreover, in later developmental stages, BMP4 induces embryonic and extra embryonic mesoderm formation (Degrelle et al, 2011) and is also related to vasculogenesis (Astorga and Carlsson, 2007) in the embryo and in the developing placenta as well. As a result, BPMs are of major importance for pregnancy success (La Rosa et al, 2011).…”