Effect of blood plasma collected after adrenocorticotropic hormone administration during the preovulatory period in the sow on oocyte in vitro maturation

Perfluorooctane sulfonate (PFOS) exposure of bovine oocytes affects early embryonic development at human-relevant levels in an in vitro model

Perfluorooctane sulfonate (PFOS) has been added to Stockholm Convention for global phase out, but will continue to contribute to the chemical burden in humans for a long time to come due to extreme persistence in the environment. In the body, PFOS is transferred into to the ovarian follicular fluid that surrounds the maturing oocyte. In the present study, bovine cumulus oocyte complexes were exposed to PFOS during 22 h in vitro maturation. Concentrations of 2 ng g^-1 (PFOS-02) representing average human exposure and 53 ng g^-1 (PFOS-53) relevant to highly exposed groups were used. After exposure, developmental competence was recorded until day 8 after fertilisation. Blastocysts were fixed and either stained to evaluate blastomere number and lipid distribution using confocal microscopy or frozen and pooled for microarray-based gene expression and DNA methylation analyses. PFOS-53 delayed the first cleavage to two-cell stage and beyond at 44 h after fertilisation (p < .01). No reduction of proportion blastocysts were seen at day 8 in either of the groups, but PFOS-53 exposure resulted in delayed development into more advanced stages of blastocysts seen as both reduced developmental stage (p = .001) and reduced number of blastomeres (p = .04). Blastocysts showed an altered lipid distribution that was more pronounced after exposure to PFOS-53 (increased total lipid volume, p=.0003, lipid volume/cell p < .0001) than PFOS-02, where only decreased average lipid droplet size (p=.02) was observed. Gene expression analyses revealed pathways differently regulated in the PFOS-treated groups compared to the controls, which were related to cell death and survival through e.g., P38 mitogen-activated protein kinases and signal transducer and activator of transcription 3, which in turn activates tumour protein 53 (TP53). Transcriptomic changes were also associated with metabolic stress response, differentiation and proliferation, which could help to explain the phenotypic changes seen in the blastocysts. The gene expression changes were more pronounced after exposure to PFOS-53 compared to PFOS-02. DNA-methylation changes were associated with similar biological functions as the transcriptomic data, with the most significantly associated pathway being TP53. Collectively, these results reveal that brief PFOS exposure during oocyte maturation alters the early embryo development at concentrations relevant to humans. This study adds to the evidence that PFOS has the potential to affect female fertility.

Effects of electromagnetic waves on oocyte maturation and embryonic development in pigs

Our living environment has been full of electromagnetic radiation (EMR) due to the prevailing electronic devices and equipment. Intermediate frequency electromagnetic field (IF-EMF) or waves constitute a significant part of EMR; therefore, an increasing number of household electrical appliances have become a source of IF-EMF, and concerns about IF-EMF on health are gaining more attention. However, little information is available about its impact on female reproductive traits, such as germ cell viability and early embryonic development, particularly at the cellular and molecular levels. In this study, we used porcine oocytes as a model system to explore the effect of IF-EMF at various intensities on the in vitro maturation (IVM) of oocytes and their subsequent embryonic development. Our results showed that no difference in oocyte maturation rates was detected among groups, but the cleavage and blastocyst rates of parthenotes derived from EMF-treated oocytes decreased with the weaker IF-EMF intensity (25 and 50 Gauss, G) groups compared to the control group (P < 0.05). For cytoplasmic maturation, the weaker IF-EMF intensity groups also showed a peripheral pattern of mitochondrial distribution resembling that of immature oocytes and increased autophagy activity. No obvious differences in cytoskeletal distribution and total cell numbers of blastocysts were investigated in the four IF-EMF treatments compared to those in the control group. Although the underlying mechanism associated with EMF effects on oocytes and embryos is still elusive, we have demonstrated that low intensity IF-EMF exerts harmful effects on porcine oocytes during the maturation stage, carrying over such effects to their subsequent embryonic development.

Effect of an altered hormonal environment by blood plasma collected after adrenocorticotropic administration on embryo development and gene expression in porcine embryos

Early embryonic development may be affected by adrenal hyperactivity in stressful situations which may lead to endocrine changes in the embryo environment. A sensitive period in porcine embryo development is the 4-cell stage when the embryo genome activation occurs. A mixed in vivo-in vitro system was implemented to test whether an altered milieu around this stage could affect embryo development and blastocyst quality in the porcine model. After in vitro maturation and fertilisation, presumptive zygotes were exposed for 24 h to plasma collected after ovulation from adrenocorticotropic hormone (ACTH)-treated, non-ACTH-treated sows; and, medium without plasma, supplemented with bovine serum albumin. Subsequently, embryo development and differences in gene expression were tested among treatments. Cleavage and blastocyst rates did not differ between treatments. Blastocyst quality by morphology assessment was similar when all the resulting blastocysts were included in the analysis. However, when only expanded blastocysts (and onwards) were included in the analysis, the blastocysts from the non-ACTH plasma group showed better quality score. Blastocyst quality by morphological assessment was not mirrored by the transcription levels of various important genes for embryo development whose gene expression profile did not significantly differ among groups. It is likely that the effect of the altered environment provided by plasma from ACTH-treated sows was too short to affect embryo development. Therefore, a brief exposure to an altered endocrine environment may not have harmful consequences for the embryo once fertilisation occurs.

In vitro fertilisation in domestic mammals-a brief overview

Many factors influence the final oocyte maturation, fertilisation, and early embryo development, and there are both similarities and differences between species. When comparing the advancement of assisted reproductive technologies (ARTs), the development in the bovine species is not far behind the medical front, with around one million in vitro-produced bovine embryos each year. This rate of progress is not seen in the other domestic species. This review aims to give an overview of the development and specific difficulties of in vitro embryo production in various domestic animal species, with the main focus on cows, pigs, and cats. In production animals, the aim of ARTs is commonly to increase the genetic progress, not to treat reproductive failure. The ARTs are also used for preservation of genetic diversity for the future. However, specifically for oocyte maturation, fertilisation, and early embryonic development, domestic mammals such as the cow and pig can be used as models for humans. This is particularly attractive from an animal welfare point of view since bovine and porcine oocytes are available in large numbers from discarded slaughterhouse material, thereby decreasing the need for research animals. Both for researchers on the animal and human medical fronts, we aim for the development of in vitro production systems that will produce embryos and offspring that are no different from those conceived and developed in vivo. Species-comparative research and development can provide us with crucial knowledge to achieve this aim and hopefully help us avoid unnecessary problems in the future.

Blood plasma collected after adrenocorticotropic hormone administration during the preovulatory period in the sow negatively affects in vitro fertilization by disturbing spermatozoa function

Successful fertilization is essential for reproduction and might be negatively affected by stressful events, which could alter the environment where fertilization occurs. The aim of the study was to determine whether an altered hormonal profile in blood plasma caused by adrenocorticotropic hormone (ACTH) administration could affect in vitro fertilization in the pig model. In experiment 1, gametes were exposed for 24 hours to plasma from ACTH-treated, non-ACTH-treated sows, or medium with BSA. Fertilization, cleavage, and blastocyst rates were lower in the ACTH group compared with the no ACTH or BSA control groups (P < 0.01). In experiment 2, the exposure of matured oocytes for 1 hour before fertilization to the same treatments did not have an impact on their ability to undergo fertilization or on embryo development. In experiment 3, spermatozoa were incubated for 0, 1, 4, and 24 hours under the same conditions. There was no effect of treatment on sperm viability. The percentage of acrosome-reacted spermatozoa remained higher in the ACTH group compared with the non-ACTH-treated group through the incubation period (P < 0.001). Protein tyrosine phosphorylation (PTP) patterns were also affected by treatment (P < 0.001). The presence of an atypical PTP pattern was higher in the ACTH group at all the analyzed time points compared with the BSA and no ACTH groups (P < 0.001). In conclusion, this altered environment may not affect oocyte competence but might affect the sperm fertilizing ability through alterations in the acrosome reaction and correct sequence of PTP patterns.

A 25 years experience of group-housed sows-reproduction in animal welfare-friendly systems

Since January 1 2013, group housing of sows has been compulsory within the European Union (EU) in all pig holdings with more than ten sows. Sows and gilts need to be kept in groups from 4 weeks after service to 1 week before the expected time of farrowing (Article 3(4) of Directive 2008/120/EC on the protection of pigs). The legislation regarding group housing was adopted already in 2001 and a long transitional period was allowed to give member states and producers enough time for adaptation. Even so, group housing of sows still seems to be uncommon in the EU, and is also uncommon in commercial pig farming systems in the rest of the world. In this review we share our experience of the Swedish 25 years of animal welfare legislation stipulating that sows must be loose-housed which de facto means group housed. The two most important concerns related to reproductive function among group-housed sows are the occurrence of lactational oestrus when sows are group-housed during lactation, and the stress that is associated with group housing during mating and gestation. Field and clinical observations in non-lactating, group-housed sows in Sweden suggest that by making basic facts known about the pig reproductive physiology related to mating, we might achieve application of efficient batch-wise breeding without pharmacological interventions. Group housing of lactating sows has some production disadvantages and somewhat lower productivity would likely have to be expected. Recordings of behavioural indicators in different housing systems suggest a lower welfare level in stalled animals compared with group-housed ones. However, there are no consistent effects on the reproductive performance associated with different housing systems. Experimental studies suggest that the most sensitive period, regarding disturbance of reproductive functions by external stressors, is the time around oestrus. We conclude that by keeping sows according to the pig welfare-friendly Directive 2008/120/EC, it is possible to combine group-housing of sows with good reproductive performance and productivity. However, substantially increased research and development is needed to optimize these systems.