Machine learning and hypothesis driven optimization of bull semen cryopreservation media.

Cryopreservation provides a critical tool for dairy herd genetics management. Due to widely varying inter- and within-bull post thaw fertility, recent research on cryoprotectant extender medium has not dramatically improved suboptimal post-thaw recovery in industry. This progress is stymied by the interactions between samples and the many components of extender media and is often compounded by industry irrelevant sample sizes. To address these challenges, here we demonstrate blank-slate optimization of bull sperm cryopreservation media by supervised machine learning. We considered two supervised learning models: artificial neural networks and Gaussian process regression (GPR). Eleven media components and initial concentrations were identified from publications in bull semen cryopreservation, and an initial 200 extender-post-thaw motility pairs were used to train and 32 extender-post-thaw motility pairs to test the machine learning algorithms. The median post-thaw motility after coupling differential evolution with GPR the increased from 52.6 ± 6.9% to 68.3 ± 6.0% at generations 7 and 17 respectively, with several media performing dramatically better than control media counterparts. This is the first study in which machine learning was used to determine the best combination of constituents to optimize bull sperm cryopreservation media, and provides a template for optimization in other cell types.

Real-time computer assisted measurement of oocyte and embryo volume for assessment of transport parameters.

Cryopreservation of gametes has revolutionized both animal agriculture and human reproductive medicine. Although many new technologies have tremendously improved the cryopreservation of oocytes and embryos, osmotic stress encountered during the equilibration process can cause their loss of function. Rational cryoprotective agent (CPA) equilibration strategies can be used to minimize this stress but require trained personnel to monitor the process in individual oocytes or embryos or require the use of suboptimal average transport parameter values in mathematically guided protocols. To enable individually optimized equilibration of CPAs in individual cells, here we establish experimental and computational techniques to track the osmotic behavior of individual bovine oocytes and embryos during CPA equilibration in real time. We designed a microfluidic device to provide a controlled flow of CPA and modified standard image analysis techniques to estimate real-time cell volume changes. In particular, we used a level-set method to define a boundary within a contour plot which could automate the image analysis process. A colour based level set algorithm coupled with contour smoothing not only provided the best fit but also reduced the segmentation time to well under a second per image. The accuracy of the automated method was comparable to human segmented images for both oocytes and embryos. This technology should enable both rapid evaluation of key biophysical parameters in oocytes and embryos undergoing CPA equilibration and the development of real-time feedback-control of CPA equilibration, enabling individual oocyte- and embryo-specific optimal protocols.

Low concentrations of 3-O-methylglucose improve post thaw recovery in cryopreserved bovine spermatozoa.

A number of studies have explored the use of membrane permeable (usually metabolizable) and membrane impermeable saccharides to protect cells in general, and sperm in particular during cryopreservation. Critical concentrations for protective levels of sugars frequently range between 50 mmol/L and 500 mmol/L, where efficacy is attributed to the sugar's membrane stabilizing and glass forming attributes and colligative effects that reduce intra- and extracellular salt concentrations during freezing. Many studies on bull sperm have demonstrated that both permeating and non-permeating sugars have negligible positive effects on post-thaw viability. Recently, however, a non-metabolizable sugar, 3-O-Methylglucose (3-OMG), was shown to protect hepatocytes during liver cryopreservation at 0.1-0.3 mol/L. Because glucose is readily transported into sperm, we hypothesized that 3-OMG could be a new class of cryoprotectant to explore in bull sperm. Here we present positive results demonstrating that 3-OMG improves post thaw viability in bull sperm, and that this effect is not likely due to improved glass forming capabilities. In particular, in experiment 1, 3-OMG was added to the Tris-egg yolk-glycerol base media at levels from 0 mmol/L to 200 mmol/L. Semen from four bulls was collected and diluted with one of the cryopreservation media, cooled, and frozen following industry standard practices. Motility and mitochondrial activity were negatively impacted when concentration of 3-OMG was more than 25 mmol/L. Therefore, we explored lower concentrations in experiment 2, where semen from eight bulls was used to evaluate concentrations 5 mmol/L, 15 mmol/L and 25 mmol/L of 3-OMG compared with control. Motility and progressive motility in 5 mmol/L 3-OMG and in the control were significantly higher than 15 mmol/L and 25 mmol/L 3-OMG, whereas mitochondrial activity and acrosome integrity in 5 mmol/L 3-OMG were significantly better than the control freezing medium. In experiment 3, to evaluate whether the improved effects of 3-OMG are due to its non-metabolizing property, or due to colligative effects, we compared post-thaw viability in semen from four bulls cryopreserved with 5 mmol/L glucose, sucrose, or 3-OMG. Motility and progressive motility was significantly improved in 3-OMG compared to glucose or sucrose groups which were comparable to the EY control. In conclusion, 3-OMG at a concentration of 5 mmol/L in Tris-egg yolk-glycerol medium improves the post thaw motility, progressive motility and viability of bull sperm. The mechanism of action is not understood but because the efficacy is maximal at low concentrations, it is not likely due to improved intra- or extracellular glass forming abilities and may demonstrate a different protective mechanism than was shown in hepatocytes.

In Vitro Development and Mitochondrial Gene Expression in Brown Brocket Deer (Mazama gouazoubira) Embryos Obtained by Interspecific Somatic Cell Nuclear Transfer.

The genetic diversity of Neotropical deer is increasingly jeopardized, owing to declining population size. Thus, the formation of cryobanking of somatic cells is important for the preservation of these species using cloning. The transformation of these cells into viable embryos has been hampered by a lack of endangered species oocytes. Accordingly, the aim of this study was to produce brown brocket deer embryos by interspecific somatic cell nuclear transfer (iSCNT), using goat or cattle oocytes as cytoplasts, and to elucidate embryo mitochondrial activity by measuring the expression levels of ATP6, COX3, and ND5. Cattle embryos produced by in vitro fertilization (IVF) were used as a control. There were no differences in the development of embryos produced by traditional SCNT and iSCNT when using either the goat cytoplasts (38.4% vs. 25.0% cleaved and 40.0% vs. 50.0% morula rates, respectively) or cattle cytoplast (72.8% vs. 65.5% cleaved and 11.3% vs. 5.9% blastocyst rates, respectively). Concerning the gene expression, no significant difference was observed when goat oocytes were used as cytoplasts. However, when using cattle oocytes and 16S as a reference gene, the iSCNT upregulated COX3, when compared with SCNT group. In contrast, when GAPDH was used as a reference gene, all the evaluated genes were upregulated in the iSCNT group, when compared with the IVF group. When compared with the SCNT group, only the expression of ATP6 was statistically different. In conclusion, it was demonstrated that interspecific nuclear transfer is a potentially useful tool for conservation programs of endangered similar deer species.

Retraction : Live birth of a Pashmina goat kid after transfer of handmade cloned embryos.

This article released online on March 5, 2019 as advance publication was withdrawn from consideration for publication in Journal of Reproduction and Development at author's request.

Live birth of a Pashmina goat kid after transfer of handmade cloned embryos.

The present study aimed to establish a zona free (handmade cloning) embryo production system for Pashmina goat embryos. Abattoir derived oocytes were matured in vitro; after maturation, oocytes were enucleated and fused with somatic cells derived from an adult Pashmina goat tissue. The reconstructs were activated using a calcium ionophore-DMAP procedure. The embryos were distributed into two experimental groups. In Experiment 1, the embryos were cultured in one of the following four culture media (i) G1.G2 media (ii) Modified synthetic oviduct fluid (mSOF) (iii) Research vitro cleave media (RVCL) and (iv) Embryo development media (EDM), and were cultured for 7 days. The cleavage rates in G1.G2, RVCL, and mSOF were higher than those in EDM (86.8, 82.4, 77.3, and 68.8%, respectively). Blastocyst rates were higher in RVCL than those in mSOF, EDM, and G1.G2 (15.0, 10.5, 4.9, and 2.2%, respectively). In experiment 2, the embryos were cultured in five different culture systems: (i) Flat surface (FS), (ii) Well in drop (WID), (iii) Well of well (WOW), (iv) Micro drop, and (v) Hanging drop, for 7 days. The cleavage rates in FS and WID were higher than those in WOW, Micro drop, and Hanging drop (84.3, 81.2, 73.6, 73.5, and 70.3%, respectively). The blastocyst rates were higher in WID than those in WOW, Micro drop, Hanging drop, and FS systems (21.6, 13.7, 11.5, 10.9, and 3.9%, respectively). The embryos produced in experiment 2 were transferred to synchronized recipients. Of the three pregnancies established on day 40, one resulted in the delivery of a healthy Pashmina kid.

The Effects of Cryopreservation on Different Passages of Fibroblast Cell Culture in Brown Brocket Deer (Mazama gouazoubira).

The brown brocket deer Mazama gouazoubira is 1 of the 10 recognized brocket deer of the Neotropical region. Recently, this species has suffered a population decline due to current threats, mainly poaching and habitat loss. Several studies have shown that some endangered species can benefit from interspecies somatic cell nuclear transfer technology through the use of their somatic cells, such as the fibroblasts. Thus, the aim of this study was to verify the viability and the effect of cryopreservation on fibroblasts after several passages. For this purpose, fibroblast cells were cultured until passages 4, 7, and 10 (cultured control groups) and cryopreserved in cryotubes (frozen/warmed groups). The cellular viability, functionality, and percentage of cells undergoing necrosis and apoptosis were evaluated. The survival rates were always higher than 80% irrespective of the tested group, except for passage 10 in the frozen/warmed group. Population doubling time of cultured cells from passage 10 was significantly higher than that of passages 4 and 7, exhibiting low metabolic activity and a higher percentage of cells in initial apoptosis. In conclusion, the M. gouazoubira fibroblast-derived cell line provides an essential resource for further studies regarding reproductive biotechniques and is likely to be useful as an ex situ conservation strategy.

The use of antifreeze protein type III for vitrification of in vitro matured bovine oocytes.

The aim of this study was to evaluate the use of antifreeze protein type III (AFP III) into vitrification medium on meiotic spindle morphology of in vitro matured bovine oocytes as well as the fertilization and blastocyst rates. Mature cumulus-oocyte complexes (COC) were distributed in four groups: control (untreated), vitrified without supplementation (AFP0) or supplemented with 500 (AFP500) or 1000 ng/mL (AFP1000) into vitrification solutions. Samples from each group were used to analyze the organization of meiotic spindle by confocal microscopy and the remaining COC were submitted to in vitro fertilization and culture for eight days. Control group exhibited only 15% of abnormal spindle. However, the spindle morphology was affected in all vitrified groups regardless to AFP concentration: 75.8%, 76.1% and 69.2% (P > 0.05) for AFP0, AFP500 and AFP1000, respectively. Similar cleavage rate was obtained among the vitrified groups (AFP0 = 17.9%, AFP500 = 16.9% and AFP1000 = 17.8%), but lower (P < 0.05) compared with control group (68.7%). At Day 5 of culture, embryo production rate of AFP500 (30.8%) and AFP1000 (25.0%) were similar to control group (49.4%). However, at Day 8 of culture, AFP0, AFP500 and AFP1000 groups exhibited lower (P < 0.05) blastocyst rates (10.0%, 3.8% and 9.4%, respectively) when compared to control (41.1%). In conclusion, AFP III did not preserve meiotic spindle organization against the cryoinjuries. However, the use of AFP III improved embryo development at Day 5 of culture, although this effect was not maintained up to the blastocyst formation.

Overexpression of hyaluronan synthase 2 and gonadotropin receptors in cumulus cells of goats subjected to one-shot eCG/FSH hormonal treatment for ovarian stimulation.

Hormonal ovarian stimulation may affect transcripts in somatic cells of cumulus-oocyte complexes (COCs) and affect the resulting oocyte quality. Here, in parallel with morphological classification and in vitro maturation (IVM) rate analysis, we investigated the expression of hyaluronan synthase 2 (HAS2), gonadotropic receptors (FSHR and LHR) and connexin 43 (GJA1) in cumulus cells (CCs) from goat COCs after multi-dose FSH (MD) or one-shot FSH/eCG (OS) treatments, using bovine COCs as control groups. The MD treatment produced more large follicles, and the resulting COCs had a better morphology and IVM rate than were obtained with OS. The OS treatment produced COCs with increased HAS2, FSHR, LHR and GJA1 expression. This gene expression pattern was also observed in the CCs of COCs that showed poor morphological characteristics. On the other hand, the mRNA levels were more similar between groups after IVM; FSHR and LHR were the main genes that showed decreased expression. Some events that occurred in bovine CCs during IVM, such as cell expansion, increased HAS2 expression and decreased GJA1 expression, were less evident or did not occur in goat COCs. In conclusion, increasing HAS2, FSHR, LHR and GJA1 expression in goat COCs does not confer greater meiotic competence to oocytes. Instead, it may result from poor regulation of gene expression in CCs by lower quality oocytes. Finally, cumulus expansion, together with HAS2 upregulation and GJA1 downregulation, seems to be more important for bovine COCs than for goat COCs. Additional studies are needed to investigate the importance of other HAS isoforms and connexins in goat COCs.

Comparison of Two Doses of Ropivacaine Hydrochloride for Lumbosacral Epidural Anaesthesia in Goats Undergoing Laparoscopy Assisted Embryo Transfer.

Goats (n = 12) undergoing laparoscopy assisted embryo transfer were randomly allotted to two groups (I and II) and injected same volume of ropivacaine hydrochloride at 1.0 mg/kg and 0.5 mg/kg body weight, respectively, at the lumbosacral epidural space. The hind quarters of all the animals were lifted up for the first 3.0 minutes following injection. Immediately after induction the animals were restrained in dorsal recumbency in Trendelenburg position in a cradle. Laparoscopy was performed after achieving pneumoperitoneum using filtered room air. Regional analgesia and changes in physiological parameters were recorded. The mean induction time in animals of group I (n = 6) was 12.666 ± 1.994 minutes. In these animals the analgesia extended up to the umbilical region and lasted for 60 minutes. Only two animals in group II were satisfactorily induced in 11.333 ± 2.333 minutes. In animals of group I, the time taken for regaining the full motor power was significantly long (405 ± 46.314 min) when compared to group II goats (95 ± 9.219 min). From this study it was concluded that ropivacaine did not produce adequate analgesia in most of the goats at 0.5 mg/kg. When used at 1.0 mg/kg, it produced satisfactory regional analgesia lasting for one hour but the prolonged motor loss precludes its use. Additional studies using ropivacaine hydrochloride at doses in between the two extremes used here may be undertaken before recommending it for lumbosacral anaesthesia in goats undergoing laparoscopy.