Bovine yolk sac: from morphology to metabolomic and proteomic profiles

Abstract

ABSTRACT. In several species, placentation involves the presence of two different membranes responsible for maternal-fetal exchanges: the yolk sac and the chorioallantoic placenta. The yolk sac plays important roles in embryonic survival, mainly during the early stages of gestation. In bovine, it is a transitional membrane that is present until day 50-70 of pregnancy. Herein, we evaluated the morphological and molecular aspects of the yolk sac of bovine embryos during 24 to 52 days of gestation. A total of 69 embryos were allocated into three groups according to the crown-rump length and estimated ages. Yolk sac samples were then subjected to morphological and molecular analysis using mass spectrometry and nuclear magnetic resonance techniques. In contrast to alanine, which was observed only in Group I, during all gestational stages, we identified important metabolites such as aspartate, taurine, glycerophosphocholine, creatinine, creatine, hydrouracil, glutamate, glutamine, lactate, lysine, valine, myo-inositol, cadaverine, and choline. In addition, 314 random sequences of proteins (2015) were identified in the bovine yolk sac, and 47 of these were considered to be specific. Changes in alpha-fetoprotein and carcinoembryonic antigen concentrations during gestation were also evaluated. In conclusion, the majority of these proteins are related to the development of secondary metabolites that are involved in the activation of other proteins and metabolites, and in signaling pathways that are responsible for maternalfetal exchanges, activation of programmed cell death mechanisms, and cellular differentiation, and also in proteins that are responsible for the yolk sac involution that is required to establish chorioallantoic placentation.

NANOG is required to form the epiblast and maintain pluripotency in the bovine embryo

“…First, the cells differentiate into the trophectoderm (TE) or the pluripotent inner cell mass (ICM), which give rise to the placental tissues, and the embryo proper, respectively (Betteridge & Fléchon, ; Chen, Wang, Wu, Ma, & Daley, ). A second lineage specification occurs at the blastocyst stage, the ICM will differentiates into the hypoblast (ruminants) or primitive endoderm (mice), which give rise to the yolk sac (Artus & Chazaud, ; Chen et al, ; Galdos‐Riveros, Favaron, Will, Miglino, & Maria, ), and the epiblast, which remains pluripotent and will constitute the embryo proper (Artus & Chazaud, ; Betteridge & Fléchon, ; Chazaud & Yamanaka, ).…”

Single-cell transcriptional landscapes of bovine peri-implantation development

“…Joint uniform manifold and projection (UMAPs) and clustering analysis revealed ten distinct cell clusters for all cells within each developmental stage ( Figures 1 B–1E and S1 E–S1H). To annotate the identities of cell clusters, we analyzed the database of known cell lineage markers in bovine, 15 , 16 , 17 , 18 , 19 humans and mouse, 20 , 21 , 22 and selected the markers that were detected in our single-cell transcriptomes of bovine peri-implantation embryos ( Data S1 ). We identified VIM , NANOG, MLY4, SLIT2, ACTA2, COL1A2, and BMP4 as marker genes of embryonic disc (ED), SOX17, GATA4, FST, FN1, CDH2 and CLU as marker genes of hypoblast (HB), and FURIN, IFNT, SFN, DAB2, PAG2 and PTGS2 as trophoblast cell markers ( Figure 1 G).…”

Developmental Hurdles That Can Compromise Pregnancy during the First Month of Gestation in Cattle

“…A subset of pregnancies generated from bovine IVP embryos exhibit various morphological abnormalities, and one of the most notable abnormalities is poorly developed yolk sacs [159,160]. The yolk sac is the primary controller of nutrient consumption and processing until day 30-40 of gestation [161,162]. The EPI is also influenced by in vitro culture.…”