Transcriptome Analysis of In Vitro Fertilization and Parthenogenesis Activation during Early Embryonic Development in Pigs

Abstract

Parthenogenesis activation (PA), as an important artificial breeding method, can stably preserve the dominant genotype of a species. However, the delayed development of PA embryos is still overly severe and largely leads to pre-implantation failure in pigs. The mechanisms underlying the deficiencies of PA embryos have not been completely understood. For further understanding of the molecular mechanism behind PA embryo failure, we performed transcriptome analysis among pig oocytes (meiosis II, MII) and early embryos at three developmental stages (zygote, morula, and blastocyst) in vitro fertilization (IVF) and PA group. Totally, 11,110 differentially expressed genes (DEGs), 4694 differentially expressed lincRNAs (DELs) were identified, and most DEGs enriched the regulation of apoptotic processes. Through cis- and trans-manner functional prediction, we found that hub lincRNAs were mostly involved in abnormal parthenogenesis embryonic development. In addition, twenty DE imprinted genes showed that some paternally imprinted genes in IVF displayed higher expression than that in PA. Notably, we identified that three DELs of imprinted genes (MEST, PLAGL1, and DIRAS3) were up regulated in IVF, and there was no significant change in PA group. Disordered expression of key genes for embryonic development might play key roles in abnormal parthenogenesis embryonic development. Our study indicates that embryos derived from different production techniques have varied in vitro development to the blastocyst stage, and they also affect the transcription level of corresponding genes, such as imprinted genes. This work will help future research on these genes and molecular-assisted breeding for pig parthenotes.

Species and embryo genome origin affect lipid droplets in preimplantation embryos

“…Additionally, there is a difference in the most active stage of transcription-morula stage for PA and blastocyst stage for IVF porcine embryos revealed by the largest number of differentially expressed genes during these stages. The PA embryos also showed enrichment in apoptosis processes (Li et al, 2021). No data on the lipid metabolism in PA vs. IVF embryos have been previously reported, which seems like a very interesting issue.…”

Single-Cell RNA Sequencing Reveals Differences in Chromatin Remodeling and Energy Metabolism among In Vivo-Developed, In Vitro-Fertilized, and Parthenogenetically Activated Embryos from the Oocyte to 8-Cell Stages in Pigs

“…These methods lead to the development of embryos that undergo multiple rounds of cleavage within a controlled laboratory environment, eventually reaching the blastocyst stage. While genome editing and somatic cell nuclear transfer techniques employed for genetic engineering purposes necessitate the use of these in vitro embryos, the PA embryo holds the advantage of stably preserving the dominant genotype [6,7]. However, when compared to embryos resulting from natural in vivo development (IVV), IVF and PA embryos exhibit noticeable phenotypic defects during embryonic development, including irregular cell morphology, slower developmental cleavage rates, lower rates of embryonic formation, lower pregnancy rate after transfer, and small litter size [8][9][10].…”

“…However, when compared to embryos resulting from natural in vivo development (IVV), IVF and PA embryos exhibit noticeable phenotypic defects during embryonic development, including irregular cell morphology, slower developmental cleavage rates, lower rates of embryonic formation, lower pregnancy rate after transfer, and small litter size [8][9][10]. PA embryos that lack paternal genomes even face embryonic mortality [6].…”