Production of collared peccary (Pecari tajacu Linnaeus, 1758) parthenogenic embryos following different oocyte chemical activation and in vitro maturation conditions

Synergistic effects of follicle-stimulating hormone and epidermal growth factor on in vitro maturation and parthenogenetic development of red-rumped agouti oocytes

Although oocyte in vitro maturation (IVM) is routinely used for in vitro embryo production in mice and rats, its use in wild rodents remains unexplored. Evidence suggests that hormone and growth factor supplementation influence oocyte meiotic resumption. This study evaluated the synergistic effects of follicle-stimulating hormone (FSH) and epidermal growth factor (EGF) on the IVM and parthenogenetic development of red-rumped agouti oocytes. Initially, we evaluated the IVM rates, mature oocyte quality, oocyte morphometry, and early embryonic development during IVM in the presence of 10, 50, and 75 mIU/mL FSH. No differences among the FSH concentrations were observed for IVM rates, oocyte morphometry, cumulus cell expansion, and viability. Although oocytes matured with 50 mIU/mL FSH showed a higher rate of cumulus expansion index (CEI), only oocytes matured with 10 mIU/mL FSH resulted in morulae after chemical activation (7.9% ± 4.2%). Thus, 10 mIU/mL FSH was used for further experiments. We subsequently evaluated the synergistic effects of 10, 50, and 100 ng/mL EGF and 10 mIU/mL FSH on the same parameters. No differences among the groups were observed in IVM rates, oocyte morphometry, and cumulus viability. Nevertheless, FSH with 10 ng/mL EGF showed a CEI superior to that of the other groups. Furthermore, oocytes matured with FSH alone or with both FSH and 10 or 50 ng/mL EGF developed morulae after activation (5.8%-8.3%). In conclusion, oocytes matured with 10 mIU/mL FSH and 10 ng/mL EGF are recommended for use in red-rumped agouti oocyte IVM, as they positively influence embryonic development.

Different Methods for Seminal Plasma Removal and Sperm Selection on the Quality and Fertility of Collared Peccary Sperm

Methods for seminal plasma (SP) removal and the selection of collared peccary sperm for fertilization were compared. The experiments evaluated the following: the (I) impact of centrifugation for SP removal before swim-up for sperm selection and (II) a comparison of different Percoll^® gradient densities (PG 45-90% and PG 35-70%). Non-selected sperm served as the control. Sperm quality was assessed based on motility patterns, morphology, membrane functional integrity, viability, reactive oxygen species (ROS), glutathione (GSH), and DNA integrity. Subsequently, the most successful group in the previous experiment and washing by centrifugation (WC) were compared for motility patterns and fertilization using pig oocytes. Swim-up decreased motility and enhanced ROS compared to the control. Centrifugation before swim-up harmed integrity and viability compared to the control. PG 45-90% (96.8 vs. 69.7 vs. 40.7 µm/s) allowed for a better velocity average pathway (VAP), a better velocity straight line, and better linearity (LIN) than those of the control and PG 35-70% (88.4 vs. 56.0 vs. 27.3 µm/s). Thus, PG 45-90% was used for fertilization. PG 45-90% obtained a higher VAP, a higher amplitude of the lateral head, straightness, and higher LIN than those of the control and WC. Cleavage (25.2-26.3%) and morula (8.1-10.5%) rates did not differ between the groups. Therefore, PG 45-90% and WC were efficient in isolating collared peccary sperm capable of fertilizing pig oocytes.

Resurrecting biodiversity: advanced assisted reproductive technologies and biobanking

Biodiversity is defined as the presence of a variety of living organisms on the Earth that is essential for human survival. However, anthropogenic activities are causing the sixth mass extinction, threatening even our own species. For many animals, dwindling numbers are becoming fragmented populations with low genetic diversity, threatening long-term species viability. With extinction rates 1000-10,000 times greater than natural, ex situ and in situ conservation programmes need additional support to save species. The indefinite storage of cryopreserved (-196°C) viable cells and tissues (cryobanking), followed by assisted or advanced assisted reproductive technology (ART: utilisation of oocytes and spermatozoa to generate offspring; aART: utilisation of somatic cell genetic material to generate offspring), may be the only hope for species' long-term survival. As such, cryobanking should be considered a necessity for all future conservation strategies. Following cryopreservation, ART/aART can be used to reinstate lost genetics back into a population, resurrecting biodiversity. However, for this to be successful, species-specific protocol optimisation and increased knowledge of basic biology for many taxa are required. Current ART/aART is primarily focused on mammalian taxa; however, this needs to be extended to all, including to some of the most endangered species: amphibians. Gamete, reproductive tissue and somatic cell cryobanking can fill the gap between losing genetic diversity today and future technological developments. This review explores species prioritisation for cryobanking and the successes and challenges of cryopreservation and multiple ARTs/aARTs. We here discuss the value of cryobanking before more species are lost and the potential of advanced reproductive technologies not only to halt but also to reverse biodiversity loss.

Lay summary

The world is undergoing its sixth mass extinction; however, unlike previous events, the latest is caused by human activities and is resulting in the largest loss of biodiversity (all living things on Earth) for 65 million years. With an extinction rate 1000-10,000-fold greater than natural, this catastrophic decline in biodiversity is threatening our own survival. As the number of individuals within a species declines, genetic diversity reduces, threatening their long-term existence. In this review, the authors summarise approaches to indefinitely preserve living cells and tissues at low temperatures (cryobanking) and the technologies required to resurrect biodiversity. In the future when appropriate techniques become available, these living samples can be thawed and used to reinstate genetic diversity and produce live young ones of endangered species, enabling their long-term survival. The successes and challenges of genome resource cryopreservation are discussed to enable a move towards a future of stable biodiversity.

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

Wild ungulates are of fundamental importance for balancing ecosystems, as well as being the species of economic interest. Increasing concern over the accelerated population reduction of these species has resulted in the development of assisted reproduction techniques, such as in vitro fertilization (IVF), as a tool for conservation and multiplication. In the present scenario, IVF protocols were developed based on the methodologies used for domestic ungulates. Nevertheless, owing to the physiological and reproductive differences among the species, several factors associated with IVF and its relationship with the characteristics of the species of interest require clarification. In vitro conditions for the collection and selection of female and male gametes, oocyte maturation, sperm capacitation, co-incubation of gametes, and embryonic development can influence IVF results. Therefore, the present review considers the main advances in the methodologies already used for wild ungulates, emphasizing the strategies for improving the protocols to obtain better efficiency rates. Additionally, we discuss the conditions of each IVF stage, with emphasis on aspects related to in vitro manipulation and comparability with the protocols for domestic ungulates.

OUP accepted manuscript

BACKGROUND

Oocyte activation deficiency (OAD) is attributed to the majority of cases underlying failure of ICSI cycles, the standard treatment for male factor infertility. Oocyte activation encompasses a series of concerted events, triggered by sperm-specific phospholipase C zeta (PLCζ), which elicits increases in free cytoplasmic calcium (Ca²⁺) in spatially and temporally specific oscillations. Defects in this specific pattern of Ca²⁺ release are directly attributable to most cases of OAD. Ca²⁺ release can be clinically mediated via assisted oocyte activation (AOA), a combination of mechanical, electrical and/or chemical stimuli which artificially promote an increase in the levels of intra-cytoplasmic Ca²⁺. However, concerns regarding safety and efficacy underlie potential risks that must be addressed before such methods can be safely widely used.

OBJECTIVE AND RATIONALE

Recent advances in current AOA techniques warrant a review of the safety and efficacy of these practices, to determine the extent to which AOA may be implemented in the clinic. Importantly, the primary challenges to obtaining data on the safety and efficacy of AOA must be determined. Such questions require urgent attention before widespread clinical utilization of such protocols can be advocated.

SEARCH METHODS

A literature review was performed using databases including PubMed, Web of Science, Medline, etc. using AOA, OAD, calcium ionophores, ICSI, PLCζ, oocyte activation, failed fertilization and fertilization failure as keywords. Relevant articles published until June 2019 were analysed and included in the review, with an emphasis on studies assessing large-scale efficacy and safety.

OUTCOMES

Contradictory studies on the safety and efficacy of AOA do not yet allow for the establishment of AOA as standard practice in the clinic. Heterogeneity in study methodology, inconsistent sample inclusion criteria, non-standardized outcome assessments, restricted sample size and animal model limitations render AOA strictly experimental. The main scientific concern impeding AOA utilization in the clinic is the non-physiological method of Ca²⁺ release mediated by most AOA agents, coupled with a lack of holistic understanding regarding the physiological mechanism(s) underlying Ca²⁺ release at oocyte activation.

LIMITATIONS, REASONS FOR CAUTION

The number of studies with clinical relevance using AOA remains significantly low. A much wider range of studies examining outcomes using multiple AOA agents are required.

WIDER IMPLICATIONS

In addition to addressing the five main challenges of studies assessing AOA safety and efficacy, more standardized, large-scale, multi-centre studies of AOA, as well as long-term follow-up studies of children born from AOA, would provide evidence for establishing AOA as a treatment for infertility. The delivery of an activating agent that can more accurately recapitulate physiological fertilization, such as recombinant PLCζ, is a promising prospect for the future of AOA. Further to PLCζ, many other avenues of physiological oocyte activation also require urgent investigation to assess other potential physiological avenues of AOA.

STUDY FUNDING/COMPETING INTERESTS

D.G. was supported by Stanford University’s Bing Overseas Study Program. J.K. was supported by a Healthcare Research Fellowship Award (HF-14-16) made by Health and Care Research Wales (HCRW), alongside a National Science, Technology, and Innovation plan (NSTIP) project grant (15-MED4186-20) awarded by the King Abdulaziz City for Science and Technology (KACST). The authors have no competing interests to declare.

Effects of Incubation Time and Method of Cell Cycle Synchronization on Collared Peccary Skin-Derived Fibroblast Cell Lines

The success of cloning by somatic cell nuclear transfer depends on the efficiency of nuclear reprogramming, with the cycle stage of the donor cell playing a crucial role. Therefore, the aim was to evaluate three different approaches for cell cycle synchronization: (i) serum starvation (SS) for 1 to 4 days, (ii) contact inhibition (CI) for 1 to 3 days, and (iii) using cell cycle regulatory inhibitors (dimethyl sulfoxide, cycloheximide, cytochalasin B, or 6-dimethylaminopurine) for 1 and 2 days, in terms of their effects on synchronization in G0/G1 phases and viability of collared peccary skin fibroblasts. Flow cytometry analysis revealed that SS for 4 days (79.0% ± 1.6) and CI for 3 days (78.0% ± 1.4) increased the percentage of fibroblasts in G0/G1 compared to growing cells GC (68.1% ± 8.6). However, SS for 3 and 4 days reduced the viability evaluated by differential staining (81.4% ± 0.03 and 81.6% ± 0.06) compared to growing cells (GC, 95.9% ± 0.06). CI did not affect the viability at any of the analyzed time intervals. No cell cycle inhibitors promoted synchronization in G0/G1. These results indicate that CI for 3 days was the most efficient method for cell cycle synchronization in peccary fibroblasts.

BMP-15 activity on in vitro development of collared peccary (Pecari tajacu Linnaeus, 1758) preantral follicles

This study investigated the effects of BMP-15 on the in vitro development of preantral follicles of collared peccaries. Ovarian fragments were cultured for 1 or 6 days in Tissue Culture Medium 199 (TCM199⁺ ) supplemented with BMP-15 at rates of 0, 1, 25 or 50 ng/ml. The fragments were analysed histologically by evaluating follicular morphology, activation and growth as well as the potential for proliferation of granulosa cells. Our results show the addition of 25 ng/ml BMP-15 in the medium provided the greatest percentage of normal follicles (79.67% ± 0.69) when compared to other treatments (p < .05); however, this result is similar to 1 ng/ml BMP-15 (74.00% ± 1.90, p > .05). Moreover, 25 and 50 ng/ml of BMP-15 promoted follicular activation. BMP-15 supplements did not affect oocyte and follicular growth. All concentrations of BMP-15 increased the number of nucleolus organizer regions (NORs) after 1 day of culture when compared to fresh fragments or the control samples (p < .05). However, at the end of the experiment, the number of NORs in follicles cultured in all treatments was higher than that observed in the fresh control (sample taken prior to culturing) (p > .05). In summary, the addition of 25 ng/ml BMP-15 to the culture medium of collared peccary preantral follicles maintained a high number of morphologically healthy follicles and stimulated the activation of primordial follicles after 6 days in culture.