Endocrine and behavioral observations during transition of non-breeding into breeding season in female American bison (Bison bison)

Analysis of progesterone and estrone-sulfate in feces of American Bison using liquid chromatography coupled to mass spectrometry: Technical validation and correlation with blood levels

American Bison's wild nature limits blood sample availability to study its endocrinology. This report describes progesterone (P4) and estrone-sulfate (E1S) assays in American Bison feces using Liquid Chromatography coupled with Mass Spectrometry (LC-MS). In 2 ranches, samples of feces (n = 73) and serum (n = 93) were collected in pregnant and nonpregnant American Bison. Feces samples (250 mg) were extracted with methanol, purified, and concentrated. Then, feces and serum samples were assayed using LC-MS, according to our previously described technique. Fecal matrix homogeneity was determined by measuring steroids in different areas of the sample and concentration evolutions were evaluated after storage at room temperature. During the validation process, lower limits of quantification were 20 pg/g (E1S) and 4 ng/g (P4) by meeting the following criteria: relative standard deviation <15% and relative bias <15%. By measuring hormones in different spots from the same sample, a moderate variability for E1S (coefficient of variation [CV] up to 21.3%) and a high variability for P4 (CV up to 85.5%) were highlighted. Correlation between concentrations in feces and in serum was higher for E1S (r = 0.77) than for P4 (r = 0.65) and P4 could be assayed in pregnant and nonpregnant animals whereas E1S was only present in pregnant. Feces storage at room temperature induced modification of steroid concentrations. The quantification of E1S and, at a lower level, of P4 in feces is an interesting alternative to serum assay to describe the pregnancy-related evolution of these steroids in American Bisons, with feces ideally stored frozen and mixed before the LC-MS procedures.

Review: Reproductive physiology of bison and application of assisted reproductive technologies to their conservation

Bison are an ecologically and culturally important species on the European and North American continents. Their near extirpation was met with conservation efforts that prevented their extinction but left few animals or highly fragmented populations. Contemporary conservation efforts are focused on building ecologically and genetically sustainable bison herds for long-term conservation of the species. Assisted reproductive technologies (ARTs) can play a key role in building these herds by facilitating the movement of genetics in the form of gametes and embryos, while protecting animal well-being and ensuring biosecurity of existing bison herds. In addition, ARTs such as gamete and embryo cryopreservation can be used to protect against future losses of genetic diversity through biobanking. In this review, a brief summary of basic bison reproductive physiology is presented followed by an overview of the current state of ART in Bison bison (American bison) and Bison bonasus (European bison or wisent). Research on ART ranging from artificial insemination to in vitro embryo transfer and cloning is discussed with particular regard to the application of ART for conservation purposes. While significant progress has been made in ART for bison, there are still many opportunities to improve these technologies and expand their impact for bison conservation.

Development and validation of a liquid chromatography coupled to mass spectrometer (LC-MS) method for the simultaneous quantification of estrone-3-sulfate, progesterone, estrone and estradiol in serum of mares and American bisons

Steroid concentrations in serum are fluctuating during pregnancy of many mammal species. The current knowledge about endocrinology of gestation is mainly based on immunoassays. However, the lack of specificity of these assays hampers the reliability of the results. In the present work, we developed and validated a methodology associating liquid chromatography (LC) and mass spectrometry (MS) to simultaneously quantify, with high specificity and accuracy, estrone-3-sulfate (E3S), progesterone (PRO), estrone (E1) and estradiol (E2) in serum of two different mammal species. The sample preparation procedure is based on a simple protein precipitation and a derivatization with dansyl chloride. After the chromatographical separation, compounds were analyzed with a triple-quadrupole mass spectrometer operating in multiple reaction monitoring. Mare and American bison serum samples were analyzed with the validated method and results were compared with concentrations measured with commercial radioimmunoassay (RIA), enzyme linked immunosorbent assay (ELISA) and chemiluminescent microparticle immunoassay (CMIA). Following these criterions: relative standard deviation <15% and relative bias <15%, lower limits of quantification of 0.5 ng/mL (E3S), 0.1 ng/mL (PRO) and 2 pg/mL (E1 and E2) were achieved. Most of the comparison between immunoassays and LC-MS showed poor correlation and proportional differences. Our LC-MS method is able to simultaneously quantify several steroid hormones with high specificity, accuracy and sensitivity in serum of two different mammal species. Our method constitutes a useful and performant tool for veterinary clinicians and LC-MS should thus be used to update and refine the current knowledge about the endocrinology of pregnancy in mammals.

Reproduction in female wild cattle: Influence of seasonality on ARTs

Wild cattle species, often considered less alluring than certain conservation-dependent species, have not attracted the same level of interest as the charismatic megafauna from the general public, private or corporate donors, and other funding agencies. Currently, most wild cattle populations are vulnerable or threatened with extinction. The implementation of reproductive technologies to maintain genetically healthy cattle populations in situ and ex situ has been considered for more than 30 years. Protocols developed for domestic cattle breeds have been used with some success in various wild cattle species. However, inherent differences in the natural life history of these species makes extrapolation of domestic cattle protocols difficult, and in some cases, minimally effective. Reproductive seasonality, driven by either photoperiod or nutritional resource availability, has significant influence on the success of assisted reproductive technologies (ARTs). This review focuses on the physiological processes that differ in breeding (ovulatory) and non-breeding (anovulatory) seasons in female cattle, and the potential methods used to overcome these challenges. Techniques to be discussed within the context of seasonality include: estrus synchronization and ovulation induction, ovarian superstimulation, artificial insemination (AI), multiple ovulation embryo transfer (MOET), and ovum pick-up (OPU) with in vitro fertilization (IVF) and embryo transfer (ET).

Effects of prolonged immunocontraception on the breeding behavior of American bison

In late 2009, the Catalina Island Conservancy began using fertility control to replace periodic removals to manage an introduced population of American bison (Bison bison) on the island. Through the application of the immunocontraceptive vaccine porcine zona pellucida (PZP), population growth was slowed within 1 year, and halted over time. In response to lingering questions about the use of PZP to manage large, free-ranging wildlife populations, we sought to determine the reversibility of PZP by ceasing the annual application to a subset of 15 bison cows and monitoring for subsequent calf arrival, and to document changes in the timing and length of the breeding season in response to PZP by monitoring breeding behavior and assessing fecal progesterone (FP) levels for all 60 resident cows over a 13-month period. As of June 2017, no new calves had been observed on the island, suggesting that, following repeated annual treatment with PZP (3 or 4 years), bison do not resume normal reproduction for at least 4 or 5 years, and that fewer treatments would be advisable if a faster return to fertility is desired. Based on observations of bull and cow behavior, and FP levels, cows displayed estrous cycles consistently throughout the study period, indicating that bison may ovulate year-round when conception and its consequences, e.g., lactation and presence of calves, are blocked. Because there is little evidence that an extended breeding season would negatively impact the health of bulls or result in large numbers of out-of-season births on Catalina, PZP appears to be a highly effective tool for managing the population of introduced bison on the island. However, the extended period of contraception and breeding activity of both cows and bulls may make PZP less suitable in high-latitude, predator-rich environments where bison conservation remains a top priority.

Validation of the BioPRYN enzyme-linked immunosorbent assay for detection of pregnancy-specific protein-B (PSPB) and diagnosis of pregnancy in American bison (Bison bison)

This study assessed the accuracy of the commercial BioPRYN^® ELISA for the detection of pregnancy-specific protein-B (PSPB) using a single blood sample to determine pregnancy status in American bison (Bison bison). A total of 49 bison cows were used in the study, and sampled at two time-points during the gestation period, fall and spring, correlating with early- to mid-term gestation (average 62.9 days post-mating) and mid- to late-term gestation (average 229.2 days post-mating), respectively. Sensitivity of the test during early- to mid-term gestation sampling period (fall) was 87.1%, while specificity was 100%; sensitivity of the test during late-term gestation sampling period (spring) was 96.3%, while specificity remained at 100%. In total, the test showed a total sensitivity of 91.4%, specificity of 100% and total accuracy of 93.8%, similar to domestic cattle. Use of the single-sample BioPRYN^® ELISA in American Bison for pregnancy diagnosis is economical and practical, minimizing animal handling time, frequency and subsequent stress while providing accurate results for pregnancy diagnosis at 62 days post-mating. This method should be considered over more traditional pregnancy diagnosis methods for use in managed bison herds.

Ovarian synchronisation in wood bison (Bison bison athabascae) during the anovulatory season

Two experiments were performed in wood bison during the anovulatory season to establish an effective protocol for ovarian synchronisation. In an untreated control phase, bison cows (n = 19) were examined daily to establish the interval to new follicular wave emergence (4.9 ± 0.7 days) for the purposes of comparison with the experimental treatments. In Experiment 1, bison were treated by transvaginal ultrasound-guided follicular ablation (n = 9) or with 2 mg, i.m., 17β-oestradiol (n = 10). In Experiment 2, bison were treated by follicular ablation (n = 9) or with 2 mg, i.m., 17β-oestradiol +100 mg, i.m., progesterone (n = 10). In Experiment 1, the interval to new wave emergence for control, follicular ablation and 17β-oestradiol-treated groups was 4.9 ± 0.7, 1.1 ± 0.1 and 3.1 ± 0.4 days, respectively (P < 0.05). The degree of synchrony was 2.4 ± 0.4, 0.2 ± 0.1 and 0.8 ± 0.2 days, respectively (P < 0.05). In Experiment 2, the interval to new wave emergence for control, follicular ablation and 17β-oestradiol + progesterone-treated groups was 4.9 ± 0.7, 1.2 ± 0.2 and 3.3 ± 0.3 days, respectively (P < 0.05), and the degree of synchrony was 2.4 ± 0.4, 0.2 ± 0.1, and 0.8 ± 0.2 days, respectively (P < 0.05). The degree of synchrony did not differ between ablation and hormone treatment groups in either experiment, but was greater in treatment groups than in the untreated control phase. Both follicular ablation and hormone treatment shortened and decreased the variability in the interval to follicular wave emergence in bison, but wave emergence occurred earlier after follicular ablation.

Cellular localisation of the pregnancy-associated glycoprotein family (PAGs) in the synepitheliochorial placenta of the European bison

This paper describes the cellular immuno-localisation of the PAG family in synepitheliochorial (cotyledonary) placenta of the European bison (Eb). Uteri were harvested from pregnant wild Eb (n=4; 45-150 days post coitum-dpc); and additionally from cattle (30, 45 dpc) and pigs (42 dpc)--both domestic species were used as positive controls for cellular PAG immunodetection. Placentas were sectioned, fixed, dehydrated and subjected to double fluorescent immunohistochemistry (dF-IHC) with the use of Alexa 488 fluorochrom (A488) and propidium iodide (PI). Native positive EbPAG signals were detected by heterologous (ht; cross-species) dF-IHC with primary rabbit anti-PAG polyclonals against native or recombinant porcine PAG antigens (anti-pPAG); then visualised with secondary anti-rabbit goat immunoglobulins--conjugated to A488. Our htdF-IHC indicated an unequivocal localisation to the mono- and bi-nuclear trophectoderm (chorionic epithelium) cells expressing the PAGs (A488-green) among all placental cells, in which PI (red) stained nuclei. This is the first paper reporting the EbPAG family expression examined by htdF-IHC at the feto-maternal interface in wild Pecoran species. The cross-reactivity of anti-pPAG polyclonals with the EbPAGs suggests that shared epitopes are present in these molecules. It seems that the EbPAG family, which is robustly expressed in mono- and bi-nucleated trophectoderm cells, is associated with events taking place during placenta development. Our study also provided a proficient ht-system to identify various PAGs that could be useful as prenatal protein markers for pregnancy diagnoses, which is essential for effective reproductive management of endangered mammals.

Isolation of pregnancy-associated glycoproteins from placenta of the American bison (Bison bison) at first half of pregnancy

This paper describes the successful purification and characterisation of pregnancy-associated glycoproteins (PAG) extracted from placenta (3-4 months) of American bisons (Amb). Chorionic AmbPAG proteins were purified from foetal cotyledonary tissues (CT) and liquid cotyledonary-carrying proteins (LCP) leaking from damaged cells. Our protocols successfully indicated the usefulness of AmbPAG protein identification, especially from LCP fraction. The AmbPAGs were extracted, precipitated and eluted during DEAE cellulose chromatography. The richest protein fractions were further chromatographed on VVA (Vicia villosa agglutinin affinity column), then characterised by mono- and bi-dimensional electrophoresis, Western blot and N-terminal amino acid (aa) sequence. After being transferred to PVDF membranes, three selected VVA-purified AmbPAG isoforms differing in molecular masses and isoelectric points (Ip 4-4.6) were selected for sequencing. One identified N-terminal 25aa sequence of AmbPAG72kDa CT form was identified as completely new (RGSNLTSLPLQNVIDLFYVGNITIG). Two other AmbPAG proteins purified from different sources (74kDa CT and 76kDa LCP forms; RGSNLTIHPLRNIRDIFYVGNITIG) were identical or corresponded to N-terminus of various bovine PAGs (boPAG). The two AmbPAGs (74kDa CT and 76kDa LCP) revealed identical micro-sequence to boPAG7; and were similar mainly to bovine PAG4, -6, -15 and -17 precursors that were identified by full-length sequencing derived from cDNA cloning. The novel sequence of the AmbPAG (72kDa CT) was related to some boPAG and various other ruminant PAG precursors (caprine and ovine). All three identified AmbPAG sequences were also relatively similar to mature forms of purified native boPAG(56-75kDa) proteins. This is the first report indicating aa sequences of native AmbPAG proteins purified from placenta (CT and LCP) of bison species. The N-terminal sequences of the AmbPAGs have been deposited in the EMBL-EBI database (UniProtKB; Accession Nos.: P84916, P84917 and P84918).