Importance of assisted reproductive technologies in the conservation of wild, rare or indigenous ungulates: review article

Ethical Analysis of the Application of Assisted Reproduction Technologies in Biodiversity Conservation and the Case of White Rhinoceros (Ceratotherium simum) Ovum Pick-Up Procedures

Originally applied on domestic and lab animals, assisted reproduction technologies (ARTs) have also found application in conservation breeding programs, where they can make the genetic management of populations more efficient, and increase the number of individuals per generation. However, their application in wildlife conservation opens up new ethical scenarios that have not yet been fully explored. This study presents a frame for the ethical analysis of the application of ART procedures in conservation based on the Ethical Matrix (EM), and discusses a specific case study—ovum pick-up (OPU) procedures performed in the current conservation efforts for the northern white rhinoceros (Ceratotherium simum cottoni)—providing a template for the assessment of ART procedures in projects involving other endangered species.

Post-mortem recovery, in vitro maturation and fertilization of fallow deer (Dama dama, Linnaeus 1758) oocytes collected during reproductive and no reproductive season

Habitat degradation leads to small and fragmented populations, lower genetic variability and fertility overtime. Assisted reproductive techniques represent important tools to cope with the dramatic loss of biodiversity. Fallow deer (Dama dama), beyond its high commercial value and wide distribution, may represent the most suitable model to study endangered cervids. In this study, oocytes were recovered post-mortem from fallow deer during the breeding and no breeding seasons and were in vitro matured (IVM). The ability of cryopreserved thawed sperm samples recovered by electroejaculation from four adult males was tested by in vitro fertilization of IVM oocytes. The number of oocytes collected per ovary did significantly vary across seasons from 6.2 ± 0.92 during breeding season to 10.4 ± 1.26 during no breeding season (p = .006). Oocytes collected during the breeding season showed higher in vitro fertilization rate compared to the no breeding season (p = .045). However, no embryos reached the blastocyst stage. Semen samples obtained by electroejaculation were successfully cryopreserved, although the cryopreservation process negatively affected most kinetic parameters, mainly at 2 hr post-thawing. Moreover, the percentage of rapid spermatozoa significantly decreased between fresh samples and at 2 hr post-thawing, whereas the percentage of slow spermatozoa increased across the same period (p < .05). Our study provides the logistic steps for the application of assisted reproductive techniques in fallow deer and might be of great interest for genetic resource bank planning.

Small Molecule Follicle-Stimulating Hormone Receptor Agonists and Antagonists

The follicle-stimulating hormone receptor (FSHR) has been targeted therapeutically for decades, due to its pivotal role in reproduction. To date, only purified and recombinant/biosimilar FSH have been used to target FSHR in assisted reproduction, with the exception of corifollitropin alfa; a modified gonadotropin in which the FSH beta subunit is joined to the C-terminal peptide of the human choriogonadotropin beta subunit, to extend serum half-life. Assisted reproduction protocols usually entail the trauma of multiple injections of FSH to initiate and promote folliculogenesis, which has prompted the development of a number of orally-available low molecular weight (LMW) chemical scaffolds targeting the FSHR. Furthermore, the recently documented roles of the FSHR in diverse extragonadal tissues, including cancer, fat metabolism, and bone density regulation, has highlighted the potential utility of LMW modulators of FSHR activity. Despite these chemical scaffolds encompassing a spectrum of in vitro and in vivo activities and pharmacological profiles, none have yet reached the clinic. In this review we discuss the major chemical classes of LMW molecules targeting the FSHR, and document their activity profiles and current status of development, in addition to discussing potential clinical applications.

The oviduct: functional genomic and proteomic approach

The mammalian oviduct is an anatomical part of the female reproductive tract, which plays several important roles in the events related to fertilization and embryo development. This review examines and compares several studies related to the proteomic and transcriptomic profile of the oviduct in different domestic animals. This information could be important for clarifying the role of oviductal factors in different events regulating fertilization and early embryo development, as well as for improving synthetic media for in vitro maturation/in vitro fertilization/embryo culture techniques (IVM/IVF/EC).

Feasibility of salvaging genetic potential of post-mortem fawns: production of sperm in testis tissue xenografts from immature donor white-tailed deer (Odocoileus virginianus) in recipient mice

The purpose of this study was to evaluate the long-term outcome of testis tissue xenografting from immature deer. Testis tissue was collected post-mortem from a 2-mo-old white-tailed deer fawn (Odocoileus virginianus) and small fragments of the tissue were grafted under the back skin of immunodeficient recipient mice (n = 7 mice; 8 fragments/mouse). Single xenograft samples were removed from representative recipient mice every 2 mo from grafting for up to 14 mo post-grafting. The retrieved xenografts were evaluated for seminiferous tubular density (per mm(2)) and tubular diameter, as well as for seminiferous tubular morphology and identification of the most advanced germ cell type present in each tubule cross section. Overall, 63% of the grafted testis fragments were recovered as xenografts. Testis tissue xenografts showed a gradual testicular development starting with tubular expansion by 2 mo, presence of spermatocytes by 6 mo post-grafting, round and elongated spermatids by 8 mo, followed by fully-formed sperm by 12 mo post-grafting. The timing of complete spermatogenesis generally corresponded to the reported timing of sexual maturation in white-tailed deer. This study demonstrated, for the first time, that testis tissue xenografting from immature deer donors into recipient mice can successfully result in testicular maturation and development of spermatogenesis in the grafts up to the stage of sperm production. These results may therefore provide a model for salvaging genetic material from immature male white-tailed deer that die before reaching sexual maturity.

Xenografting of testis tissue from bison calf donors into recipient mice as a strategy for salvaging genetic material

The objective was to evaluate the long-term outcome of testis tissue xenografting from neonatal bison calves as a model for closely related rare or endangered ungulates. Testis tissue was collected postmortem from two newborn bison calves (Bison bison bison) and small fragments of the tissue were grafted under the back skin of immunodeficient recipient mice (n = 15 mice; eight fragments/mouse). Single xenograft samples were removed from representative recipient mice every 2 mo after grafting (for up to 16 mo). The retrieved xenografts were evaluated for seminiferous tubular density, tubular diameter, seminiferous tubular morphology, and identification of the most advanced germ cell type. Overall, 69% of the grafted testis fragments were recovered as xenografts. Xenografts weight increased (P < 0.02) approximately four-fold by 2 mo and 10-fold by 16 mo post-grafting. In testis xenografts, gradual maturational changes were evident, manifested as the first detection of the following at the times specified: seminiferous tubule expansion, 2 mo; spermatocytes, 6 mo; round spermatids, 12 mo; and elongated spermatids, 16 mo. Furthermore, there were differences between the two donor calves regarding the efficiency of spermatogenesis in xenografts. The timing of complete spermatogenesis approximately corresponded to the reported timing of sexual maturation in bison. This study demonstrated, apparently for the first time, that testis tissue xenografting from neonatal bison donors into recipient mice resulted in testicular maturation and complete development of spermatogenesis in the grafts.

Washing increases the susceptibility to exogenous oxidative stress in red deer spermatozoa

The effects of routine sperm work are often overlooked. We assessed the effect of washing cryopreserved epididymal spermatozoa from red deer (Cervus elaphus hispanicus, Helzheimer 1909). After thawing, epididymal samples (four stags) were diluted in TALP-HEPES. A split was left untouched, another was centrifuged (300 x g, 5 min) and resuspended, and a third was centrifuged and the supernatant substituted by fresh TALP-HEPES (washing). Each split was supplemented either with nothing, 1mM of the antioxidant Trolox, 100 microM of the oxidant Fe (with ascorbate), or both. The 3x4 treatments were incubated at 37 degrees C and assessed each hour up to 3h for motility (computer-aided sperm assessment) and viability/apoptosis plus mitochondrial status (YO-PRO-1, propidium iodide, Mitotracker Deep Red; flow cytometry). DNA damage at 4h was assessed using the terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling assay. Centrifugation alone affected neither sperm quality nor DNA, and the oxidant had no effect in control or centrifuged samples. Washed samples were not different than control, but oxidant decreased motility, mitochondrial status and viability, and altered the motility subpopulation pattern, being partially suppressed by Trolox. Spermatozoa with damaged DNA dramatically increased in the washed-oxidized sample (from 22.30+/-3.52% to 67.94+/-5.07%), but not when antioxidant was present. Although samples from different males behaved similarly, male-to-male variability was detected regarding susceptibility to oxidative damage after washing. We concluded that, although red deer thawed spermatozoa seemed resilient to centrifugation, the vulnerability to oxidative stress after washing makes it advisable to supplement manipulation media with antioxidants, especially taking into account male-to-male variability.

Sperm parameters on Iberian red deer: electroejaculation and post-mortem collection

Artificial reproductive technologies (ART) for cervids have improved, but a need remains for the collection of basic data. We studied two models of sperm collection in Iberian red deer, post-mortem (PM) in a wild population (179 samples) and by electroejaculation (EE) in a farmed population (37 samples), recording: testicular and epididymal weight, testicular diameter, sperm quantity, pH and osmolality and spermatozoa quality (motility by CASA, abnormal forms, cytoplasmic droplets, viability and acrosomal status). We tested the relationship of these parameters with stag age and compared the two models (PM and EE; medians showed). Genitalia parameters were linearly related to stag age (testicular diameter: 31.5-50.5mm for 2-9 years). Total number of spermatozoa collected were PM: 2.5x10(9) and EE: 3.6x10(9) (P>0.05), increasing with age only for PM. We found a positive relationship between testicular size and spermatozoa collected for PM. Osmolality and pH were PM: 6.28 and 378mOsm/kg; EE: 7.63 and 309mOsm/kg (P<0.05). The pH increased with age only for EE. Percentage of motile spermatozoa was similar for PM and EE, but motility quality was lower for PM. Abnormal forms, proximal and distal droplets were lower for EE (22%, 1.3%, 1.5% vs. PM: 23%, 4.3%, 83%). Viability was similar (74%) and intact acrosomes were higher for EE (97% vs. 89%). Both PM and EE samples could be used for germplasm banking. This study contributes with new data on red deer spermatology and for the development of ART in cervids.

Ovulation synchronization following commercial application of ultrasound-guided follicle ablation during the estrous cycle in mares

A regimen of progesterone plus estradiol (P&E) was used as a standard for ovarian synchronization to test the efficacy and evaluate the commercial application of ultrasound-guided follicle ablation as a non-steroidal alternative for ovulation synchronization in mares. Recipient mares at a private embryo transfer facility were at unknown stages of the estrous cycle at the start of the experiment on Day 1 when they were randomly assigned to an ablation group (n=18-21 mares) or to a P&E group (n=20-21 mares). In the ablation group, mares were lightly sedated and all follicles > or = 10 mm were removed by transvaginal ultrasound-guided follicle aspiration. In the P&E group, a combination of progesterone (150 mg) plus estradiol (10mg) prepared in safflower oil was given daily (im) for 10 d. Two doses of prostaglandin F(2alpha) (PGF, 10mg/dose, im) were given 12 h apart on Day 5 in the ablation group, or a single dose on Day 10 in the P&E group. Human chorionic gonadotropin (hCG, 2500 IU/mare, im) was given at a fixed time, 6 and 10 d after PGF treatment in the ablation and P&E groups, respectively, with the expectation of a follicle > or = 30 mm at the time of treatment. In both the ablation and P&E groups, transrectal ultrasonography was done at the start of the study (Day 1) and again on the day of hCG treatment and daily thereafter to determine the presence of a CL, measure diameter of the largest follicle and detect ovulation. The mean interval from the start of the study and from PGF treatment to ovulation was shorter (P<0.0001) in the ablation group (13.7 and 9.7 d, respectively) compared to the P&E group (22.3 and 13.2 d, respectively). Following fixed-day treatment with hCG after PGF treatment, the degree of ovulation synchronization was not different (P>0.05) between the ablation and P&E groups within a 2-d (56 and 70%) or 4-d (83% and 90%) period. Although ultrasound-guided follicle ablation may not be practical in all circumstances, it excluded the conventional 10-d regimen of progesterone and estradiol and was considered an efficacious and feasible, non-steroidal alternative for ovulation synchronization in mares during the estrous cycle.

Toward culture of single gametes: the development of microfluidic platforms for assisted reproduction

During the last few decades in vitro production of mammalian embryos and assisted reproductive technologies such as embryo transfer, cryopreservation, and cloning have been used to produce and propagate genetically superior livestock. However, efficiencies of these technologies remain low. For these technologies to become more commercially viable, the efficiencies must improve. Despite this importance of reproduction for the livestock industry, little progress in decreasing embryonic mortality has been made. The livestock industry has succeeded in achieving large increases in average milk production of dairy cattle, growth rate in beef cattle and leanness in swine but reproductive efficiency has actually decreased. For example, research has provided little progress toward developing an objective method to examine viability of a single living embryo. At the same time, the growth of miniaturization technologies beyond integrated circuits and toward small mechanical systems has created opportunities for fresh examination of a wide range of existing problems. While the investigation and application of miniaturization technologies to medicine and biology is progressing rapidly, there has been limited exploration of microfabricated systems in the area of embryo production. Microfluidics is an emerging technology that allows a fresh examination of the way assisted reproduction is performed. Here we review the progress in demonstrating microfluidic systems for in vitro embryo production (IVP) and embryo manipulation. Microfluidic technology could have a dramatic impact on the development of new techniques as well as on our basic understanding of gamete and embryo physiology.

Seminal plasma improves cryopreservation of Iberian red deer epididymal sperm

We tested the protective action of seminal plasma on epididymal spermatozoa from Iberian red deer, especially considering cryopreservation, as a means for germplasm banking improvement. We obtained seminal plasma by centrifuging electroejaculated semen, and part of it was thermically inactivated (denatured plasma; 55 degrees C 30 min). Epididymal samples (always at 5 degrees C) were obtained from genitalia harvested after regulated hunting, and pooled for each assay (five in total). We tested three seminal plasma treatments (mixing seminal plasma with samples 2:1): no plasma, untreated plasma and denatured plasma; and four incubation treatments: 32 degrees C 15 min, 5 degrees C 15 min, 5 degrees C 2h and 5 degrees C 6h. After each incubation, samples were diluted 1:1 with extender: Tes-Tris-Fructose, 10% egg yolk, 4% glycerol; equilibrated for 2h at 5 degrees C, extended down to 10(8) spz./mL and frozen. Sperm quality was evaluated before 1:1 dilution, before freezing and after thawing the samples, assessing motility (CASA) and viability (percentage of viable and acrosome-intact spermatozoa; PI/PNA-FITC and fluorescent microscopy). Plasma treatment, both untreated and denatured, rendered higher viability before freezing and higher results for most parameters after thawing. The improvement was irrespective of incubation treatment, except for viability, which rendered slightly different results for untreated and denatured plasma. This may be due to the presence of thermolabile components. We still have to determine the underlying mechanisms involved in this protection. These results might help to improve the design of cryopreservation extenders for red deer epididymal sperm.

Effects of cryopreservation of mouse embryos and in vitro fertilization on genotypic frequencies in colonies

To evaluate the effects of cryopreservation and in vitro fertilization (IVF) on genotypic frequencies in mouse colonies, genotypic frequencies at 15 biochemical, 4 immunological and 20 microsatellite loci were examined in three colonies of MCH (ICR) mice derived from noncryopreserved embryos obtained by natural mating without the induction of superovulation, cryopreserved embryos obtained by natural mating with the induction of superovulation, and cryopreserved embryos obtained by the induction of superovulation and IVF. Three (Pgm-1, Ldr-1 and Hbb) out of the 15 biochemical loci, two (Thy-1 and H2K) out of four immunological loci and five (D5Mit18, D6Mit15, D12Mit5, D13Mit26, and D14Mit7) out of 20 microsatellite loci that showed polymorphisms in every colony were used for detection of genotypic frequencies. The genotypic frequencies of the loci in the three colonies did not differ from the predicted genotypic frequencies (P > 0.05). The results suggested that genetic drift does not occur among colonies established from treated and untreated embryos, and it was clear that the embryo banking by cryopreservation is suitable for preservation of outbred stock without genetic drift.