How in vitro maturation changes the proteome of ovine cumulus-oocyte complexes?

The present study evaluated the effects of in vitro maturation (IVM) on the proteome of cumulus-oocyte complexes (COCs) from ewes. Extracted COC proteins were analyzed by LC-MS/MS. Differences in protein abundances (p < 0.05) and functional enrichments in immature versus in vitro-matured COCs were evaluated using bioinformatics tools. There were 2550 proteins identified in the COCs, with 89 and 87 proteins exclusive to immature and mature COCs, respectively. IVM caused downregulation of 84 and upregulation of 34 proteins. Major upregulated proteins in mature COCs were dopey_N domain-containing protein, structural maintenance of chromosomes protein, ubiquitin-like modifier-activating enzyme 2. Main downregulated proteins in mature COCs were immunoglobulin heavy constant mu, inter-alpha-trypsin inhibitor heavy chain 2, alpha-2-macroglobulin. Proteins exclusive to mature COCs and upregulated after IVM related to immune response, complement cascade, vesicle-mediated transport, cell cycle, and extracellular matrix organization. Proteins of immature COCs and downregulated after IVM were linked to metabolic processes, immune response, and complement cascade. KEGG pathways and miRNA-regulated genes attributed to downregulated and mature COC proteins related to complement and coagulation cascades, metabolism, humoral response, and B cell-mediated immunity. Thus, IVM influenced the ovine COC proteome. This knowledge supports the future development of efficient IVM protocols for Ovis aries.

Global proteomic analysis of preimplantational ovine embryos produced in vitro.

The present study was conducted to characterize the major proteome of preimplantation (D6) ovine embryos produced in vitro. COCs were aspirated from antral follicles (2-6 mm), matured and fertilized in vitro and cultured until day six. Proteins were extracted separately from three pools of 45 embryos and separately run in SDS-PAGE. Proteins from each pool were individually subjected to in-gel digestion followed by LC-MS/MS. Three 'raw files' and protein lists were produced by Pattern Lab software, but only proteins present in all three lists were used for the bioinformatics analyses. There were 2,262 proteins identified in the 6-day-old ovine embryos, including albumin, zona pellucida glycoprotein 2, 3 and 4, peptidyl arginine deiminase 6, actin cytoplasmic 1, gamma-actin 1, pyruvate kinase, heat shock protein 90 and protein disulfide isomerase, among others. Major biological processes linked to the sheep embryo proteome were translation, protein transport and protein stabilization, and molecular functions, defined as ATP binding, oxygen carrier activity and oxygen binding. There were 42 enriched functional clusters according to the 2,147 genes (UniProt database). Ten selected clusters with potential association with embryo development included translation, structural constituent of ribosomes, ribosomes, nucleosomes, structural constituent of the cytoskeleton, microtubule-based process, translation initiation factor activity, regulation of translational initiation, cell body and nucleotide biosynthetic process. The most representative KEEG pathways were ribosome, oxidative phosphorylation, glutathione metabolism, gap junction, mineral absorption, DNA replication and cGMP-PKG signalling pathway. Analyses of functional clusters clearly showed differences associated with the proteome of preimplantation (D6) sheep embryos generated after in vitro fertilization in comparison with in vivo counterparts (Sanchez et al., 2021; https://doi.org/10.1111/rda.13897), confirming that the quality of in vitro derived blastocysts are unlike those produced in vivo. The present study portrays the first comprehensive overview of the proteome of preimplantational ovine embryos grown in vitro.

Generation of a Human Deafness Sheep Model Using the CRISPR/Cas System.

CRISPR/Cas9 system is a promising method for the generation of human disease models by genome editing in non-conventional experimental animals. Medium/large-sized animals like sheep have several advantages to study human diseases and medicine. Here, we present a protocol that describes the generation of an otoferlin edited sheep model via CRISPR-assisted single-stranded oligodinucleotide-mediated Homology-Directed Repair (HDR), through direct cytoplasmic microinjection in in vitro produced zygotes.Otoferlin is a protein expressed in the cochlear inner hair cells, with different mutations at the OTOF gene being the major cause of nonsyndromic recessive auditory neuropathy spectrum disorder in humans. By using this protocol, we reported for the first time an OTOF KI model in sheep with 17.8% edited lambs showing indel mutations, and 61.5% of them bearing knock-in mutations by HDR . The reported method establishes the bases to produce a deafness model to test novel therapies in human disorders related to OTOF mutations.

Is prostaglandin F2α administration at the beginning of a progesterone and estradiol-based treatment for FTAI an effective strategy in Bos taurus heifers?

The objective was to evaluate effects of prostaglandin (PG) F2α administration at the beginning of a progesterone and estradiol-based treatment period on ovarian response and pregnancy rate (P/AI) in Bos taurus beef heifers. Heifers were treated with 500 µg of cloprostenol administered: a) in two half-doses (250 µg) at the time of progesterone device insertion and removal (two-PG), or b) in a single dose at the time of device removal (one-PG). In the two-PG group, administration of PG at device insertion resulted in lesser serum progesterone concentrations during the 7-d treatment period (P < 0.05). Additionally, diameter of the follicle from which ovulation occurred was greater, and ovulation occurred earlier in the two-PG compared with one-PG group (P < 0.05). Fixed-time artificial insemination (FTAI) was performed in 3479 heifers with two times for FTAI (48 compared with 54 h from device removal). There was no effect on P/AI percentage for the PG treatment or the time of FTAI. The FTAI at 54 h resulted in a greater P/AI percentage in the one-PG than two-PG group (70.5%, 253/359 and 63.5%, 254/400, respectively; P < 0.05). There were no differences between PG treatments when FTAI was performed at 48 h after device removal. In conclusion, the administration of PG at the time of intravaginal progesterone device insertion results in lesser progesterone concentrations, and an increased size of the follicle from which ovulation occurs, and the time of ovulation is earlier after device removal. The pregnancy rate was not affected by the PG administration at the time of device insertion.

Impact of delipidated estrous sheep serum supplementation on in vitro maturation, cryotolerance and endoplasmic reticulum stress gene expression of sheep oocytes.

High lipid content of oocytes and embryos in domestic animals is one of the well-known factors associated with poor cryosurvival. Herein, we wanted to determine whether the use of delipidated estrous sheep serum during in vitro maturation (IVM) of ovine oocytes reduces the cytoplasmic lipid droplets content and improves embryo development and cryotolerance after vitrification. Cumulus oocytes complexes (COCs) were matured in vitro for 24 h in medium supplemented with whole or delipidated estrous sheep serum prior to vitrification. Neutral lipid present in lipid droplets of COCs, cleavage rate, embryo development rate on Day 6 and Day 8, and hatching rate on Day 8, were compared among experimental groups. Endoplasmic reticulum stress genes were evaluated in in vitro matured COCs under different lipid conditions prior to vitrification. The lipid droplets' content (mean fluorescence intensity) of oocytes cultured with IVM media supplemented with delipidated serum was lower than COCs matured with whole serum (7.6 ± 1.7 vs. 22.8 ± 5.0 arbitrary units, respectively; P< 0.05). Despite IVM treatment, oocytes subjected to vitrification showed impaired competence compared with the non-vitrified groups (P<0.05). No significant differences in embryo production were observed in non-vitrified COCs after maturation in delipidated or whole serum (33.4±4.9 vs 31.9 ±4.2). COCs matured in delipidated serum and subjected to vitrification showed increased expression of ATF4, ATF6, GRP78, and CHOP10 genes (ER stress markers). Collectively, our results demonstrate that although supplementation of IVM medium with delipidated estrous sheep serum reduces the presence of cytoplasmic lipid droplets in oocytes after maturation, oocyte cryotolerance is not improved. Notably, the expression of genes associated with the unfolded protein response (UPR) was increased in COCs, with fewer lipid droplets subjected to vitrification, suggesting that oocyte cryopreservation is associated with ER stress and activation of adaptive responses.