Docosahexaenoic acid supplementation during porcine oocyte in vitro maturation improves oocyte quality and embryonic development by enhancing the homeostasis of energy metabolism

Although supplementation with docosahexaenoic acid (DHA) during porcine oocyte IVM is well-established, the available data are limited due to the lack of consistency. Moreover, to our knowledge, the anti-oxidant effects of DHA on porcine oocytes have not been reported. Hence, this study aimed to examine the effects of DHA supplementation on the regulation of energy metabolism during porcine oocyte maturation to improve oocyte maturation and embryonic development. By supplementing the IVM medium with various DHA concentrations, 25 μM DHA was identified as the optimal concentration which improved intraoocyte glutathione content and enhanced embryonic development after parthenogenesis. Compared to embryos derived from the control group, those derived from SCNT or IVF showed significantly improved blastocyst formation upon DHA supplementation during IVM. In addition, various transcription factors associated with oocyte development and apoptosis in mature oocytes were beneficially regulated in the DHA-treated oocytes. Moreover, DHA improved the AMP-activated protein kinase (AMPK)-regulatory ability of porcine oocytes and ameliorated nuclear maturation and embryonic development, which were decreased by artificially downregulating AMPK. To our knowledge, this is the first study to examine the effects of DHA as an AMPK regulator on oocyte maturation and embryo development in pigs. Furthermore, DHA addition to the IVM medium upregulated the relative expression of genes associated with mitochondrial potential and lipid metabolism. Therefore, the membrane potential of mitochondria (evaluated based on the JC-1 aggregate/JC-1 monomer ratio) and the levels of fatty acids and lipid droplets in matured oocytes increased, resulting in increased ATP synthesis. In conclusion, the DHA treatment of porcine oocytes with 25 μM DHA during IVM enhances the homeostasis of energy metabolism by improving mitochondrial function and lipid metabolism, leading to improved quality of matured oocytes and enhanced embryonic developmental potential of in vitro produced (IVP) embryos. Thus, 25 μM DHA supplementation could serve as a tool for improving the quality of IVP embryos. The study findings provide a basis for further research on improving the production efficiency of cloned animals by securing high-quality matured oocytes and enhancing energy metabolism in mammalian oocytes, including those of pigs.

Analysis of production efficiency of cloned transgenic Yucatan miniature pigs according to recipient breeds with embryo transfer conditions

The purpose of this study was to compare the efficiency of the production of cloned transgenic Yucatan miniature pigs (YMPs) using two recipient breeds, i.e., YMPs and domestic pigs (DPs), under various embryo transfer conditions. We initially assessed the in vitro developmental competence of embryos obtained via somatic cell nuclear transfer (SCNT) from three different transgenic donor cells. No difference was observed among the three groups regarding developmental competence. Furthermore, the cloning efficiency remained consistent among the three groups after the transfer of the SCNT embryos to each surrogate mother. Subsequently, to compare the efficiency of the production of cloned transgenic YMPs between the two recipient breeds using varying parameters, including ovulation status (preovulation and postovulation), duration of in vitro culture (IVC) (incubated within 24 h and 24-48 h), and the number of transferred SCNT embryos (less than and more than 300), we assessed the pregnancy rates, delivery rates, mean offspring counts, and cloning efficiency. Regarding the ovulation status, YMPs exhibited higher pregnancy rates, delivery rates, and cloning efficiency compared with DPs in both statuses. Moreover, the pregnancy rates, delivery rates, and cloning efficiency were affected by the ovulation status in DPs, but not in YMPs. The comparison of IVC duration between groups revealed that YMPs had higher pregnancy rates vs. DPs in both conditions. SCNT embryos cultured for 24-48 h in YMPs yielded higher delivery rates and cloning efficiency compared with those cultured for less than 24 h in DPs. Finally, the analysis based on the number of transferred SCNT embryos showed that both the pregnancy and delivery rates were higher in YMPs vs. DPs. However, the highest average number of offspring was obtained when more than 300 SCNT embryos were transferred into DPs, whereas the cloning efficiency was higher in YMPs vs. DPs. Our results suggest that YMPs are more suitable recipients than are DPs under various conditions for the production of cloned transgenic YMPs.

Supplementation with fibroblast growth factor 7 during in vitro maturation of porcine cumulus-oocyte complexes improves oocyte maturation and early embryonic development

In vitro generation of porcine embryos is an indispensable method in the realms of both agriculture and biomedicine. Nonetheless, the extant procedures encounter substantial obstacles pertaining to both the caliber and efficacy of the produced embryos, necessitating extensive research to in vitro maturation (IVM), the seminal commencement phase. One potentially fruitful approach may lie in refining the media and supplements composition utilized for oocyte maturation. Fibroblast growth factor-7 (FGF7), alternatively termed keratinocyte growth factor, is a theca-derived cytokine integral to folliculogenesis. This study aimed to examine the ramifications of supplementing FGF7 during the IVM phase. To determine the FGF7 location and its receptor in porcine ovaries, immunohistochemistry was executed based on follicle size categories (1-2, 3-6, and 7-9 mm). Regardless of follicle size, it was determined that FGF7 was expressed in theca and granulosa cells (GCs), whereas the FGF7 receptor was only expressed in the GCs of the larger follicles. During the IVM process, the maturation medium was supplied with various concentrations of FGF7, aiming to mature porcine cumulus-oocyte complexes (COCs). The data indicated a significant augmentation in the nuclear maturation rate only within the group treated with 10 ng/mL of FGF7 (p < 0.05). Post-IVM, the oocytes diameter exhibited a significant expansion in all groups that received FGF7 supplementation (p < 0.05). Additionally, all FGF7-supplemented groups exhibited a substantial elevation in intracellular glutathione levels, coupled with a noticeable reduction in reactive oxygen species levels (p < 0.05). With respect to gene expressions related to apoptosis, FGF7 treatment elicited a downregulation of pro-apoptotic genes and an upregulation of anti-apoptotic genes. The expression of genes associated with antioxidants underwent a significant enhancement (p < 0.05). In terms of the FGF7 signaling pathway-associated genes, there was a significant elevation in the mRNA expression of ERK1, ERK2, c-kit, and KITLG (p < 0.05). Remarkably, the group of 10 ng/mL of FGF7 demonstrated an appreciable uptick in the blastocyst formation rate during embryonic development post-parthenogenetic activation (p < 0.05). In conclusion, the FGF7 supplementation during IVM substantially augments the quality of matured oocytes and facilitates the subsequent development of parthenogenetically activated embryos. These results offer fresh perspectives on improved maturation and following in vitro evolution of porcine oocytes.

Nutrition, female fertility and in vitro fertilization outcomes

The investigation of modifiable factors that may exert influences on female reproductive health and in vitro fertilization (IVF) outcomes is increasing. Growing attention is being paid to nutrition. The aim of the present review is to recapitulate the current understanding on the effects of nutrition on female fertility and IVF outcomes. In particular, the three main classes of macromolecules have been analysed i.e. carbohydrates, proteins and fatty acids. An increasing number of studies have focused on the potential benefit of whole grain, vegetables and omega-3 polynsatured fatty acids (ω-3 PUFAs) on reproductive outcomes. Controversial results exist regarding the consumption of omega-6 (ω-6) PUFAs and dairy. Overall, nutrition appears to represent a modifiable factor that may play a significant role in the context of female reproduction and IVF outcomes, but the limited number of studies and the discrepancies between the available data call for further research in the area.

Linoleic and linolenic acids reduce the effects of heat stress-induced damage in pig oocytes during maturation in vitro

Elevated environmental temperatures can induce heat stress which could reduce fertility and early embryonic development. Fatty acids can initiate an endergonic reaction that absorbs cellular heat and decreases intracellular temperature. This study's objective was to minimize heat stress-induced damage to in vitro matured oocytes by supplementing maturation media with either 50 μM linoleic or linolenic acid or both (25 or 50 μM) during maturation at either 38.5 or 41.5°C. Oocytes were evaluated for intracellular antioxidative pathways, fertilization characteristics, or early embryonic development. Elevated maturation temperatures increased (p < 0.05) reactive oxygen species (ROS) formation and supplementation with linoleic or linolenic acid decreased (p < 0.05) ROS in oocytes matured at 41.5°C. Maturation temperature had an effect (p < 0.05) on the intracellular antioxidative pathways of the oocyte except for glutathione peroxidase activity. Regardless of maturation temperature, supplementation with linoleic or linolenic acid increased (p < 0.05) the enzyme activities and glutathione concentrations in the oocytes compared to no fatty acid supplementation. Supplementation of both linoleic and linolenic acid decreased (p < 0.05) polyspermic fertilization rates. Supplementing either 25 or 50 μM linoleic and linolenic acid to maturing oocytes at 41.5°C increased (p < 0.05) cleavage rates by 48 h after IVF and the blastocyst formation rates by 144 h after IVF compared to other treatments. Oocytes matured at 38.5°C had greater (p < 0.05) embryonic development than those matured at 41.5°C except for those supplemented with 50 μM linoleic and linolenic acid. Supplementing 50 μM linoleic and linolenic acid to the maturation medium of pig oocytes reduces the effects of heat stress-induced damage.

Comparative transcriptome analysis identifies important maternal molecules and associated biological pathways for pig and human mature oocytes

Recent researches reveal that during oocyte maturation, species-specific molecular profile exists, and has important functional roles. However, molecular differences between pig (a larger animal model for human reproduction) and human mature oocytes remain unknown. Here, by comparative transcriptome analyses of single cell RNA-seq data, we aimed to identify the common and unique maternal factors and associated biological processes between in vivo and in vitro matured pig oocytes, and between in vitro matured human and pig oocytes. Annotated protein coding mRNAs were identified in pig in vivo (11147) and in vitro (11997), and human in vitro (14491) MII oocytes, respectively. For in vivo and in vitro derived pig MII oocytes, 10551 annotated maternal mRNAs were common, mainly enriched in signaling pathways such as cell cycle, oocyte meiosis, microtubule cytoskeleton, MAPK, RNA processing/binding. Besides, in vivo (596) and in vitro (1446) pig MII-specific mRNAs and their involved signaling pathways (in vivo: Bmp, calcium-mediated signaling, PI3K-Akt; in vitro: growth factor activity, JAK-STAT, cytokine-cytokine receptor interaction, calcium signaling pathway) were also found. As for in vitro derived human and pig MII oocytes, 10285 annotated mRNAs were common, enriched in a variety of signaling pathways (cell cycle, oocyte meiosis, microtubule, AMPK, RNA splicing, protein serine/threonine kinase activity, etc). In vitro MII-specific mRNAs were found for humans (4206) and pigs (1712), which were also enriched in species-specific signaling pathways (humans: golgi related terms, transcription repressor and hormone activity; pigs: ATP biosynthetic process, G protein-coupled peptide receptor activity, animoacyl-tRNA biosynthesis), respectively. These findings improve our understanding on oocyte maturation, and also the limitations of pig model for human oocyte maturation and fertilization.

Comparative Study of Three Raspberry Cultivar (Rubus idaeus L.) Leaves Metabolites: Metabolome Profiling and Antioxidant Activities

Raspberry (Rubus idaeus L.), known as one of the famous healthy fruits an d are consumed fresh or processed products all over the world. The antioxidation activity of raspberry fruits as well as leaves have been widely investigated. To better understand the metabolite accumulation mechanisms and to develop different functional cultivars, we performed a non-targeted metabolomics analysis using LC-MS/MS to investigate the contents of existing components from three raspberry cultivars, Autumn Britten, Autumn Bliss, and Red Autumn leaves, respectively. The results show multiple differentially accumulated metabolites among three cultivars, especially for the lipids (α-linolenic acid and eicosatetraenoic acid), amino acids and their derivatives (L-cysteine, Phenylalanine), flavonoids (Kaempferol 3-O-rhamnoside-7-O-glucoside, Quercetin 3-glucoside), and vitamins (Biotin, Thiamine, Vitamin K2), etc. The in vitro cellular antioxidant activities of three raspberry cultivars leaves ethanol extracts (RLEE) were also characterized. Through comparison the superoxide dismutase (SOD), glutathione (GSH), catalase (CAT), and reactive oxygen species (ROS) levels before or after RLEE protection of L929 fibroblast cells upon excessive UVB exposure, we evaluated the antioxidation potentials for all three cultivar RLEEs. It turns out the raspberry Autumn Britten leaf extract holds the greatest potential for protecting the L929 fibroblast cells from UVB induced damage. Our study provides theoretical support for screening of active metabolites from three raspberry cultivars leaves, spanning metabolites’ accumulation to cell damage protection, which could be used to refine bioactivity assessment for different raspberry cultivars suitable for antioxidant products extraction.

Pterostilbene Alleviates Chlorpyrifos-Induced Damage During Porcine Oocyte Maturation

Chlorpyrifos (CPF), a widely used organophosphate pesticide, is reported to severely impair mammalian reproductive system. Pterostilbene (PTS), an effective free radical scavenger, is considered as beneficial for mammalian reproduction. However, the toxicity of CPF on oocyte maturation and whether PTS can eliminate the detrimental effect of CPF on oocytes remain unclear. Here, porcine oocytes were applied to investigate the potential effect and possible mechanism of CPF and PTS during oocyte maturation. This work demonstrated that CPF significantly delayed the meiotic progression and decreased the polar body extrusion by disturbing spindle assembly and chromosome alignment and causing DNA damage in oocytes (p < 0.05). And, CPF significantly impaired oocyte cytoplasmic maturation by inducing the high level of reactive oxygen species and decreasing glutathione content (p < 0.05). Moreover, CPF significantly triggered embryo apoptosis and reduced the blastocyst rate and cell number following parthenogenetic activation (p < 0.05). Whereas CPF-exposed oocytes were treated with PTS, these defects caused by CPF were obviously rescued, and oocyte maturation and subsequent embryonic development were also significantly ameliorated (p < 0.05). In conclusion, these results revealed that CPF exerted the toxic effect on porcine oocytes, while PTS effectively alleviated CPF-induced damage on oocytes. This work provides a potential strategy to protect oocyte maturation in mammalian species.

In vitro maturation using αMEM containing reduced NaCl enhances maturation and developmental competence of pig oocytes after somatic cell nuclear transfer

Background

Compared to medium containing 108 mM sodium chloride (NaCl), in vitro maturation (IVM) using a simple medium with reduced (61.6 mM) NaCl increases the cytoplasmic maturation and embryonic development of pig oocytes.

Objectives

This study determines the effect of a complex medium containing reduced NaCl on the IVM and embryonic development of pig oocytes.

Methods

Pig oocytes were matured in Minimum Essential Medium Eagle-alpha modification (αMEM) supplemented with 61.6 (61αMEM) or 108 (108αMEM) mM NaCl, and containing polyvinyl alcohol (PVA) (αMEMP) or pig follicular fluid (PFF) (αMEMF). Medium-199 (M199) served as the control for conventional IVM. Cumulus cell expansion, nuclear maturation, intra-oocyte glutathione (GSH) contents, size of perivitelline space (PVS), and embryonic development after parthenogenesis (PA) and somatic cell nuclear transfer (SCNT) were evaluated after IVM.

Results

Regardless of PVA or PFF supplementation, oocytes matured in 61αMEM showed increased intra-oocyte GSH contents and width of PVS (p < 0.05), as well as increased blastocyst formation (p < 0.05) after PA and SCNT, as compared to oocytes matured in 108αMEMP and M199. Under conditions of PFF-enriched αMEM, SCNT oocytes matured in 61αMEMF showed higher blastocyst formation (p < 0.05), compared to maturation in 108αMEMF and M199, whereas PA cultured oocytes showed no significant difference.

Conclusions

IVM in αMEM supplemented with reduced NaCl (61.6 mM) enhances the embryonic developmental competence subsequent to PA and SCNT, which attributes toward improved oocyte maturation.

Pig Cloning Using Somatic Cell Nuclear Transfer

Porcine cloning technology can be used to produce progenies genetically identical to the donor cells from high-quality breeding pigs. In addition, genetically modified pigs have been produced by somatic cell nuclear transfer using genetically modified porcine fetal fibroblasts. The method of preparing genetically modified pigs is critical for establishing pig models for human diseases, and for generating donor animals for future xenotransplantation. This chapter describes detailed procedures for generating cloned pigs using fetal fibroblasts as nuclear donors.

Glucose in a maturation medium with reduced NaCl improves oocyte maturation and embryonic development after somatic cell nuclear transfer and in vitro fertilization in pigs

This study was conducted to examine whether glucose in maturation medium containing reduced NaCl could improve oocyte maturation and embryonic development in pigs. The base medium was bovine serum albumin-free porcine zygote medium (PZM)-3 containing 10% (v/v) pig follicular fluid (FPZM) or 0.1% (w/v) polyvinyl alcohol (PPZM). Using each medium, the effects of NaCl concentrations (108 and 61.6 mM) and 5.56 mM glucose supplementation (designated as PZM108N, PZM108G, PZM61N, and PZM61G, respectively) were examined using a 2 × 2 factorial arrangement. When oocytes were matured in FPZM, glucose supplementation improved nuclear maturation compared with no supplementation, regardless of the NaCl concentrations. FPZM61G showed a higher blastocyst formation compared with FPZM108N and FPZM108G after parthenogenesis (PA). Blastocyst formations of somatic cell nuclear transfer (SCNT) embryos derived from FPZM61N and FPZM61G were higher compared with those of oocytes from FPZM108N. When oocytes were matured in PPZM, glucose added to PPZM108 and PPZM61 increased nuclear maturation compared with no supplementation. However, glucose added to PPZM108 did not alter embryonic development after PA. Additionally, oocytes matured in PPZM61G showed a higher blastocyst formation compared with those from PPZM61N. In SCNT, blastocyst formation was not influenced by glucose supplementation of PPZM108, but was increased by maturation in glucose-supplemented PPZM61. In embryonic development of in vitro fertilization (IVF), oocytes matured in medium with reduced NaCl and glucose showed significantly higher blastocyst formation compared with those matured in PPZM108G. Our results demonstrated that glucose in maturation medium containing 61.6 mM NaCl increased oocyte maturation and embryonic development after PA, SCNT, and IVF.

Stimulation of follicle growth and development during estrus in Ettawa Grade does fed a flushing supplement of different polyunsaturated fatty acids

Background and Aim

Flushing with the manipulation of fatty acids, particularly polyunsaturated fatty acids, like linoleic and α-linolenic acids in the ration, is a strategy to raise the nutritional status of the female mammals to improve ovarian function and follicle development. This study was designed to investigate the effectiveness of flushing supplementation with different types of polyunsaturated and saturated fatty acids in stimulating follicle growth and development during estrus in Ettawa Grade does with a low initial body condition score (BCS ≤2).

Materials and Methods

Eighteen Ettawa Grade does in the second parity, with an average body weight of 32.11±2.19 kg, were divided into three groups according to the fatty acid supplemented to their ration: (i) About 2.8% lauric acid flushing (group); (ii) 2.8% linoleic acid flushing (LA group); and (iii) 2.8% α-linolenic acid flushing (ALA group). The ration was formulated to be isocaloric (total digestible nutrient = 77%) and isonitrogenous (crude protein = 15%). The experiment was conducted for 35 days; that is, 14 days for acclimatization and synchronization of the estrous cycle and 21 days for fatty acid flushing until the appearance of the next estrus. A completely randomized design was applied.

Results

According to the results, none of the different fatty acids in the ration affected the nutrient intakes, BCSs, average daily gains, and plasma glucose, cholesterol, and progesterone concentrations of the three groups of does. However, the BCSs (by 0.8-0.9) and the plasma cholesterol concentrations were higher after fatty acid flushing for 21 days than before the flushing period. The ALA group had the highest number of large-sized preovulatory follicles, whereas the LAURIC group had the highest plasma estradiol concentration during estrus. All three groups had similar plasma progesterone concentrations during estrus after fatty acid flushing.

Conclusion

Flushing supplementation with 2.8% ALA from flaxseed oil gave the best results in terms of stimulating the highest number of large-sized preovulatory follicles in Ettawa Grade does.

Chitosan nanoparticles enhance developmental competence of in vitro-matured porcine oocytes

Oxidative stress is inevitable as it is derived from the handling, culturing, inherent metabolic activities and medium supplementation of embryos. This study was performed to investigate the protective effect of chitosan nanoparticles (CNPs) on oxidative damage in porcine oocytes. For this purpose, cumulus-oocyte complexes (COCs) derived from porcine slaughterhouse ovaries were exposed to different concentrations of CNPs (0, 10, 25 and 50 µg/ml) during in vitro maturation (IVM). Oocytes treated with 25 µg/ml CNPs showed significantly higher levels of GSH, along with a significant reduction in ROS levels compared to control, CNPs10 and CNPs50 groups. In parthenogenetic embryo production, the maturation rate was significantly higher in the CNPs25 group than that in the control and all other treated groups. In addition, when compared to the CNPs50 and control groups, CNPs25-treated oocytes showed significantly higher cleavage and blastocyst development rates. The highest concentration of CNPs reduced the total cell number and ratio of ICM: TE cells in parthenogenetic embryos, suggesting that there is a threshold where benefits are lost if exceeded. In cloned embryos, the CNPs25 group, as compared to all other treated groups, showed significantly higher maturation and cleavage rates. Furthermore, the blastocyst development rate in the CNPs25-treated group was significantly higher than that in the CNPs50-treated group, as was the total cell number. Moreover, we found that cloned embryos derived from the CNPs25-treated group showed significantly higher expression levels of Pou5f1, Dppa2, and Ndp52il genes, compared with those of the control and other treated groups. Our results demonstrated that 25 µg/ml CNPs treatment during IVM improves the developmental competence of porcine oocytes by reducing oxidative stress.

Elevation of MPF and MAPK gene expression, GSH content and mitochondrial distribution quality induced by melatonin promotes porcine oocyte maturation and development in vitro

The MPF and MAPK genes play crucial roles during oocyte maturation processes. However, the pattern of MPF and MAPK gene expression induced by melatonin (MT) and its correlation to oocyte maturation quality during the process of porcine oocyte maturation in vitro remains unexplored. To unravel it, in this study, we cultured the porcine oocytes in maturation medium supplemented with 0, 10⁻⁶, 10⁻⁹, and 10⁻¹² mol/L melatonin. Later, we analyzed the MPF and MAPK gene expression levels by RT-PCR and determined the maturation index (survival and maturation rate of oocytes). The GSH content in the single oocyte, and cytoplasmic mitochondrial maturation distribution after porcine oocyte maturation in vitro was also evaluated. We also assessed the effects of these changes on parthenogenetic embryonic developmental potential. The oocytes cultured with 10⁻⁹mol/L melatonin concentration showed higher oocyte maturation rate, and MPF and MAPK genes expression levels along with better mitochondrial distribution than the 0, 10⁻⁶, and 10⁻¹² mol/L melatonin concentrations (p < 0.05). No significant difference was observed in the survival rates when the oocytes were cultured with different melatonin concentrations. The expression of the MPF gene in the oocytes cultured with 10⁻⁶ mol/L melatonin was higher than with 10⁻¹² and 0 mol/L melatonin, and the expression of the MAPK gene in 10⁻⁶ and 10⁻¹² group was higher than the control (p < 0.05). As far as the embryonic developmental potential is concerned, the cleavage and blastocyst rate of oocytes cultured with 10⁻⁶ and 10⁻⁹ mol/L melatonin was significantly higher than the 10⁻¹² mol/L melatonin and control. In conclusion, 10⁻⁹–10⁻⁶ mol/L melatonin significantly induced the MPF and MAPK gene expression; besides, it could also be correlated with GSH content of single oocyte, mitochondrial maturation distribution, and the first polar body expulsion. These changes were also found to be associated with parthenogenetic embryo developmental potential in vitro.

Single cell RNA-seq reveals molecular pathways altered by 7, 12-dimethylbenz[a]anthracene treatment on pig oocytes

Oocytes of better quality and developmental competence are highly demanded, which is affected by many intrinsic and external factors, including environmental pollutants. We have previously demonstrated that 7, 12-dimethylbenz [a]anthracene (DMBA) reduces the developmental competence of porcine oocytes, by desynchronizing nuclear and ooplasmic maturation. However, the underlying molecular mechanism remains obscure. Here we performed single cell RNA-seq to study the transcriptome changes in DMBA-treated porcine MII oocytes, and identified 19 protein-coding genes and 156 novel long non-coding RNAs (lncRNAs) with abundance to be significantly different (P < 0.05), which enriched in signaling pathways such as glycosphingolipid biosynthesis, nicotine addiction, basal transcription factors and nucleotide excision repair. RT-qPCR on oocyte pools confirmed ornithine aminotransferase (Oat) and serine/arginine-rich splicing factor 4 (Srsf4) to be significantly up- and down-regulated, respectively (P < 0.05). Treating porcine COCs with MAPK and PLC pathway inhibitors suppressed DMBA's effects on increasing PB1 extrusion rate. In addition, DMBA co-incubation with 250 μM vitamin C derivative (l-ascorbic acid 2-phosphate sesquimagnesium salt hydrate, AA2P) and 100 μM co-enzyme Q10 (CoQ10) could significantly reduce the DMBA-induced high ROS level, and partially alleviate the DMBA-induced high PB1 rate, whereas the cleavage and blastocyst rates of parthenotes derived from treated mature oocytes remained to be low. Collectively, our findings indicate that single cell RNA-seq can help reveal the dynamics of molecular signaling pathways for porcine oocytes treated by DMBA, and supplement of anti-oxidative reagents could not sufficiently rescue DMBA-induced defects of porcine oocytes.

Source and Follicular Fluid Treatment During the In Vitro Maturation of Recipient Oocytes Affects the Development of Cloned Pig Embryo

Pig cloning technique is valuable in agriculture, biomedicine, and life sciences. However, the full-term developmental efficiency of cloned pig embryos is only about 1%, which limits pig cloning application. The quality of recipient oocytes greatly affects the developmental competence of cloned pig embryos. Thus, this study investigated the effects of a recipient oocyte source (in vivo matured [IVVM] oocytes vs. slaughter house-derived in vitro matured [IVTM] oocytes), and follicular liquid treatment (slaughter house-derived immature follicle-derived fluid [IFF] vs. in vivo-matured follicle-derived fluid [MFF]) during the in vitro maturation (IVM) of oocytes on the development of the cloned pig embryos. Our results showed that using IVVM oocytes to replace IVTM oocytes as recipient oocytes, and using 10% MFF IVM medium to replace 10% IFF IVM medium could enhance the development of the cloned pig embryos. IFF and MFF contained different levels of oocyte quality-related proteins, resulting in different oocyte quality-related gene expression levels and reactive oxygen species levels between the 10% MFF medium-cultured oocytes and 10% IFF medium-cultured oocytes. This study provided useful information for enhancing the pig cloning efficiency by improving the quality of recipient oocytes.

Mammalian ovarian lipid distributions by desorption electrospray ionization-mass spectrometry (DESI-MS) imaging

Merging optical images of tissue sections with the spatial distributions of molecules seen by imaging mass spectrometry is a powerful approach to better understand the metabolic roles of the mapped molecules. Here, we use histologically friendly desorption electrospray ionization-mass spectrometry (DESI-MS) to map the lipid distribution in tissue sections of ovaries from cows (N = 8), sows (N = 3), and mice (N = 12). Morphologically friendly DESI-MS imaging allows the same sections to be examined for morphological information. Independent of the species, ovarian follicles, corpora lutea, and stroma could be differentiated by principal component analysis, showing that lipid profiles are well conserved among species. As examples of specific findings, arachidonic acid and the phosphatidylinositol PI(38:4), were both found concentrated in the follicles and corpora lutea, structures that promoted ovulation and implantation, respectively. Adrenic acid was spatially located in the corpora lutea, suggesting the importance of this fatty acid in the ovary luteal phase. In summary, lipid information captured by DESI-MS imaging could be related to ovarian structures and data were all conserved among cows, sows, and mice. Further application of DESI-MS imaging to either physiological or pathophysiological models of reproductive conditions will likely expand knowledge of the roles of specific lipids and pathways in ovarian activity and mammalian fertility. Graphical abstract Desorption electrospray ionization-mass spectrometry (DESI-MS) is performed directly from frozen ovarian tissue sections placed onto glass slides. Because the desorption and ionization process of small molecules is so gentle, the tissue architecture is preserved. The sample can then be stained and tissue morphology information can be overlaid with the chemical information obtained by DESI-MS.

Effects of polyunsaturated fatty acids on the development of pig oocytes in vitro following parthenogenetic activation and on the lipid content of oocytes and embryos

As oocytes and embryos of pigs have greater lipid content in the cytoplasm than those of other species, supplementation of the medium for in vitro maturation (IVM) of oocytes with omega-3 polyunsaturated fatty acids (PUFA) may help to improve embryo development. This study was conducted to evaluate effects of the inclusion of the docosaexaenoic (DHA) and of the eicosapentaenoic acids (EPA) in the IVM medium on the development of pig oocytes and on the lipid content of oocytes and embryos. In all experiments, control media consisted of porcine follicular fluid and oocytes were activated through parthenogenesis. In Experiment 1, there were four treatments for each PUFA: one control; and three treatments including EPA or DHA in the IVM medium at 12.5 μM, 25.0 μM and 50.0 μM). In Experiment 2, inclusion of 50 μM DHA was compared against the control. Cleavage rates in the IVM medium including 12.5 μM EPA and blastocyst development rates in media at any EPA concentration were less than for the control in Experiment 1 (P <  0.05). Compared to the control, inclusion of 50 μM DHA in the IVM medium was related to greater cleavage rates and greater number of embryo cells, in Experiment 1, and lesser lipid content in oocytes after 22 and 44 h and in embryos after 7 days, in Experiment 2 (both P <  0.05). Addition of DHA in the IVM medium may benefit the development of pig oocytes, but EPA appears to be cytotoxic.

Alpha-Linolenic Acid: It Contribute Regulation of Fertilization Capacity and Subsequent Development by Promoting of Cumulus Expansion during Maturation

The objective of this study was to evaluate the effects of alpha-linolenic acid (ALA) during in vitro maturation (IVM) on cumulus expansion, nuclear maturation, fertilization capacity and subsequent development in porcine oocytes. The oocytes were incubated with 0, 25, 50, and 100 μM ALA. Cumulus expansion was measured at 22 h, and gene expresison and nuclear maturation were analyzed at 44 h after maturation. Then, mature oocytes with ALA were inseminated, and fertilization parameters and embryo development were evaluated. In results, both of cumulus expansion and nuclear maturation were increased in 50 μM ALA groups compared to control groups (p<0.05). However, expression of gap junction protein alpha 1 (GJA1, cumulus expansion-related gene), delta-6 desaturase (FADS1, fatty acid metabolism-related gene), and delta-5 desaturase (FADS2) mRNA in cumulus cells were reduced by 50 μM ALA treatment (p<0.05). Cleavage rate was enhanced in 25 and 50 μM ALA groups (p<0.05), especially, treatment of 50 μM ALA promoted early embryo develop to 4 and 8 cell stages (p<0.05). However, blastocyst formation and number of cells in blastocyst were not differ in 25 and 50 μM ALA groups. Our findings show that ALA treatment during maturation could improve nuclear maturation, fertilization, and early embryo development through enhancing of cumulus expansion, however, fatty acid metabolism- and cumulus expansion-related genes were down-regulated. Therefore, addition of ALA during IVM of oocytes could improve fertilization and developmental competence, and further studies regarding with the mechanism of ALA metabolism are needed.

Expression Changes in Fatty acid Metabolic Processrelated Genes in Porcine Oocytes During in Vitro Maturation

Mammalian oocytes undergo compound processes of nuclear and cytoplasmic maturation that allow them to reach MII stage. Only fully mature, oocyte can be successfully fertilized by a single spermatozoon. Fatty acids, apart from their role in cellular metabolism, inflammation and tissue development, have positive and detrimental effects on oocyte maturation, fertilization, blastocyst cleavage rate and embryo development in mammals. Using microarrays, we have analyzed the expression changes in fatty acids- -related genes during in vitro maturation of porcine oocytes. The oocytes were recovered from ovaries of 45 pubertal crossbred Landrace gilts and subsequently subjected to BCB test. For further analyses, only granulosa cell-free BCB+ oocytes were used and divided into two groups. The first one, described as “before IVM”, was directly exposed to molecular assays, the second one, described as “after IVM”, was first in vitro matured and then subjected to a second BCB test. Oocytes, if classified as BCB+, were then passed to corresponding molecular analyses. We found significant down-regulation of genes involved in fatty acid metabolic process, such as: ACSL6, EPHX2, FADS2, PTGES, TPI1, TBXAS1, NDUFAB1, MIF, ACADSB and DECR1 in porcine oocytes analyzed after IVM, in comparison to those analyzed before IVM. In conclusion, apart from poor data available concerning analyzed genes in relation to reproductive events, significant changes in their expression point to their potential role as an oocyte developmental competence markers in pigs. Introducing molecular diagnostics of oocytes could be the prospective tool for selection of best gametes, leading to improved outcomes of in vitro fertilization.

Action mechanisms of n-3 polyunsaturated fatty acids on the oocyte maturation and developmental competence: Potential advantages and disadvantages

Infertility is a growing problem worldwide. Currently, in vitro fertilization (IVF) is widely performed to treat infertility. However, a high percentage of IVF cycles fails, due to the poor developmental potential of the retrieved oocyte to generate viable embryos. Fatty acid content of the follicular microenvironment can affect oocyte maturation and the subsequent developmental competence. Saturated and monounsaturated fatty acids are mainly used by follicle components as primary energy sources whereas polyunsaturated fatty acids (PUFAs) play a wide range of roles. A large body of evidence supports the beneficial effects of n-3 PUFAs in prevention, treatment, and amelioration of some pathophysiological conditions including heart diseases, cancer, diabetes, and psychological disorders. Nevertheless, current findings regarding the effects of n-3 PUFAs on reproductive outcomes in general and on oocyte quality more specifically are inconsistent. This review attempts to provide a comprehensive overview of potential molecular mechanisms by which n-3 PUFAs affect oocyte maturation and developmental competence, particularly in the setting of IVF and thereby aims to elucidate the reasons behind current discrepancies around this topic.

Effect of Alpha-Linolenic Acid on Oocyte Maturation and Embryo Development in Pigs

The aim of this study was to determine the effect of additional alpha-linolenic acid (ALA) supplementation during in vitro maturation (IVM) and culture (IVC) on nucleic maturation and embryo development of pigs. Cumulus-oocyte complexes (COCs) were incubated in IVM medium containing different concentration of ALA (25, 50 and 100 μM) for 44 h. After in vitro maturation, nuclear maturation of oocytes were evaluated by aceto-orcein stain. Mature oocytes with 50 μM ALA were fertilized and cultured in IVC medium with ALA (25, 50 and 100 μM) during early-embryogenesis (48 hours after fertilization). Then, embryos were cultured with 25 μM ALA during early embryogenesis and/or late embryogenesis (120 hours after early-embryogenesis). In results, oocyte maturation were significantly increased by 50 μM ALA treatment groups compared with control groups (p<0.05). Treatment of 25 μM ALA during early-embryogenesis enhanced cleavage rate of embryo compared with other groups (p<0.05), whereas formation and total cell number of blastocyst had no significant difference. Similarly, cleavage rate of embryos were increased by 25 μM ALA supplement during early- or late-embryogenesis than ALA treatment both stage of embryogenesis (p<0.05), but did not influence to blastocyst formation. Interestingly, total cell number of blastocyst were enhanced in ALA treatment group during early-embryogenesis. These findings indicated that ALA supplement enhance the nuclear maturation of oocyte and embryo development, however, excessive ALA could negatively influence. Therefore, we suggest that ALA is used for improvement of in vitro production of mammalian embryo and further study regarding with functional mechanism of ALA is needed.

Effect of rapamycin treatment during post-activation and/or in vitro culture on embryonic development after parthenogenesis and in vitro fertilization in pigs

This study investigated the effects of early induction of autophagy on embryonic development in pigs. For this, oocytes or embryos were treated with an autophagy inducer, rapamycin (RP), during post-activation (Pa), in vitro fertilization (IVF) and/or in vitro culture (IVC). When parthenogenesis (PA) embryos were untreated (control) or treated with various concentrations of RP for 4 hr during Pa, 100 nm RP showed a higher blastocyst formation (48.8 ± 2.7%) than the control (34.6 ± 3.0%). When PA embryos were treated during the first 24 hr of IVC, blastocyst formation was increased (p < .05) by 1 and 10 nm RP (61.9 ± 3.0 and 59.6 ± 3.0%, respectively) compared to the control (43.2 ± 1.8%) and 100 nm RP (47.8 ± 3.2%), with a higher embryo cleavage in response to 10 nm RP (87.3 ± 2.4%) than the control (74.1 ± 3.2%). RP treatment during IVC and Pa + IVC showed increased blastocyst formation (44.7 ± 2.5 and 44.1 ± 2.0%, respectively) compared to the control (33.2 ± 2.0%). In addition, RP treatment during Pa and/or IVC increased glutathione content and inversely reduced reactive oxygen species. In IVF, RP treatment for 6 hr during IVF significantly increased embryonic development (34.0 ± 2.6%) compared to the control (24.8 ± 1.6%), but treatment during IVC for 24 hr with RP did not (23.0 ± 3.8%). Autophagy was significantly increased in PA oocytes by the RP treatment during Pa but not altered by the treatment during the first 24 hr of IVC. Overall, RP treatment positively regulated the pre-implantation development of pig embryos, probably by regulating cellular redox state and stimulating autophagy.