Single-Cell RNA-Seq Revealed the Gene Expression Pattern during the In Vitro Maturation of Donkey Oocytes

Abstract

Donkeys are an important domesticated animal, providing labor, meat, milk, and medicinal materials for humans. However, the donkey population is continuously declining and even at risk of extinction. The application of modern animal production technology, such as oocyte in vitro maturation, is a promising method to improve the donkey population. In this study, we explore the gene expression patterns of donkey germinal vesicle (GV) and in vitro matured metaphase II (MII) oocytes using single cell RNA-seq of the candidate genes along with the regulatory mechanisms that affect donkey oocyte maturation. We identified a total of 24,164 oocyte genes of which 9073 were significant differentially expressed in the GV and MII oocytes. Further Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated that these genes were associated with the meiotic cell cycle, mitochondrion activity, and N-glycan biosynthesis, which might be the key genes and regulatory mechanisms affecting the maturation of donkey oocytes. Our study provides considerable understanding regarding the maturation of donkey oocytes and serves as a theoretical basis for improving the development of donkey oocytes, which could ultimately benefit the expansion of the donkey population and conservation of biodiversity and genetic resources.

Transcriptome analyses reveal transcriptional profiles of horse oocytes before and after in vitro maturation

“…was also excavated in the previous reports on donkey oocytes (Li, Song, et al, 2021). This study also found that ADCY3, PDE3B, ACAA1, ACAA2, ACLY, OGDHL and other DEGs in MII oocytes were also down-regulated compared with GV stage.…”

“…Transcriptome analysis during oocyte maturation has been implemented in many animals, such as sheep (Fang, Xia, et al, 2022), pigs (Fang, Wu, et al, 2022), and donkeys (Li, Song, et al, 2021). Few studies have been conducted on horse oocytes yet.…”

“…Then place on the clean table to carefully remove the tissues such as fallopian tubes, mesangium, and blood vessels attached to the horse's ovaries, and finally blot the surface with absorbent paper (sterilized). Referring to previous reports (Li, Song, et al, 2021), all antral follicles were opened with a scalpel blade and the granulosa cell (GC) layer was scraped with a curette without omission. COC were recovered using a dissecting microscope and examined and sorted (Lange Consiglio et al, 2010).…”

Comparative Transcriptomics Uncover the Uniqueness of Oocyte Development in the Donkey

“…The current study made an in-depth exploration of gene expression characteristics by thoroughly comparing the similarities and differences in oocyte development during GV-MII between donkeys and cattle, sheep, pigs, and mice (Qian et al, 2019;Wang et al, 2020b;Du et al, 2021;Li et al, 2021a;Li et al, 2021b), Furthermore, the release of the newly assembled donkey reference genome and the update of bioinformatics analysis tools (Wang C. et al, 2020), allowed us to annotate donkey genes more accurately, and to obtaining more refined results. Interestingly, in terms of transcriptome characteristics, we found that the GV and MII phases formed two groups of cells with a clear dividing line (Figure 1).…”

Embryo production by in vitro fertilization in wild ungulates: progress and perspectives – A Review

“…In vicunas, 41% of oocytes matured in vitro after 27 h, which is a shorter time than for other domesticated camelids (Chaves et al, 2004). Finally, in rhinoceros, an IVM time of 36-44 h has been reported (Hildebrandt et al, 2018), which is the approximate time for horses and donkeys (Li et al, 2021). Therefore, establishing the IVM time is an initial step in obtaining oocytes suitable for fertilization.…”