PXD067319-1

PXD067319 is an original dataset announced via ProteomeXchange.

Title	Epiblast production and thereby totipotency of the first two blastomeres is balanced or unbalanced depending on the region where the oocyte was fertilized
Description	Following fertilization in mice and humans, the first two blastomeres are not equivalent but one produces more epiblast than the other, so that they do not feature equal totipotency. Research into the causes has overlooked that the epiblast imbalance is preceded by a fertilization imbalance, since in nature the spermatozoon fertilizes the oocyte preferentially in the animal hemisphere. We conceived a hypothesis that the two imbalances are linked to each other, and broke it down into testable predictions. If the two imbalances were interdependent, then changing the site of sperm entry in the oocyte should change the extent of epiblast imbalance. Thus, we evened out the fertilization imbalance, using intracytoplasmic sperm injection (ICSI) to fertilize mouse oocytes also in the vegetal hemisphere as well as in the cortex around the animal-vegetal midline (equator). Resultant embryos were bisected at the 2-cell stage, and the twin blastocysts originated from the sister blastomeres were analyzed. Against similarity in mRNA levels of epiblast genes, twin blastocysts differed in function, as measured by NANOG protein expression and derivation of embryonic stem cells, and the epiblast imbalance was greater after oocyte fertilization at the equator. There is no simple way to explain the positional effect other than through differences in molecular composition of the ooplasm, which, moreover, should also be apportioned variably at first zygotic division. We tested these predictions by measuring the orientation of first zygotic division with respect to the ICSI site; and by measuring the composition of bisected oocytes’ hemispheres using half-cell proteomics. Since the hemispheres have different compositions depending on the bisection axis, and since the angle of the first division is variable, we propose that variable partition of non-homogeneous ooplasm sets the stage for the epiblast imbalance. These results attest to the architectural influence of maternal factors on mammalian embryogenesis.
HostingRepository	PRIDE
AnnounceDate	2026-01-19
AnnouncementXML	Submission_2026-01-19_08:34:49.790.xml
DigitalObjectIdentifier
ReviewLevel	Peer-reviewed dataset
DatasetOrigin	Original dataset
RepositorySupport	Unsupported dataset by repository
PrimarySubmitter	Hannes Drexler
SpeciesList	scientific name: Mus musculus (Mouse); NCBI TaxID: NEWT:10090;
ModificationList	acetylated residue; iodoacetamide derivatized residue
Instrument	timsTOF Pro 2

Revision	Datetime	Status	ChangeLog Entry
0	2025-08-13 13:50:08	ID requested
⏵ 1	2026-01-19 08:34:50	announced

Dataset with its publication pending

submitter keyword: blastocyst, LC-MSMS, proteomics,oocyte, epiblast, epiblast imbalance, monozygotic twins

Hannes C. A. Drexler
contact affiliation	Max Planck Institute for Molecular Biomedicine Mass Spectrometry Unit Röntgenstr. 20 48149 Münster Germany
contact email	hannes.drexler@mpi-muenster.mpg.de
lab head
Hannes Drexler
contact affiliation	Bioanalytical Mass Spectrometry, Max Planck Insitute for Molecular Biomedicine, Roentgenstr. 20, 48149 Münster, Germany
contact email	hannes.drexler@mpi-muenster.mpg.de
dataset submitter

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PRIDE project URI

• PRIDE
  1. PXD067319
     1. Label: PRIDE project
     2. Name: Epiblast production and thereby totipotency of the first two blastomeres is balanced or unbalanced depending on the region where the oocyte was fertilized