Ovarian dynamics in progesterone tablet-induced superovulation in goats assessed by magnetic resonance imaging

Controlled internal drug-releasing (CIDR) devices are commonly used for superovulation in goats. However, such devices are unavailable in some countries, including Japan. In this technical note, we aimed to explore the efficacy of an alternative superovulation protocol using progesterone tablets in goats. We employed intravaginal progesterone tablets (LUTINAS® Vaginal Tablet 100 mg) following a standard superovulation protocol. Additionally, we assessed the ovarian dynamics using 3T-magnetic resonance imaging (MRI) 1 day preceding the progesterone treatment (Day "-1") and 3 days before the end of treatment (Days 11-13). The ovarian monitoring was successfully performed in the short tau inversion recovery T2-weighted images of MRI, and ovulation was confirmed by the disappearance of follicles on Day 13 post-administration of the tablets. Immediately after ovulation, oviduct flushing yielded a substantial number of oocytes (13.5 ± 1.8 oocytes per animal). These findings provide evidence that the administration of progesterone tablets can serve as a viable alternative for inducing. Additionally, our findings suggest that 3T-MRI is a promising alternative to conventional ultrasonography for monitoring ovarian dynamics following superovulation in experimental goats.

Genome editing for disease resistance in livestock

One of the major burdens on the livestock industry is loss of animals and decrease in production efficiency due to disease. Advances in sequencing technology and genome-editing techniques provide the unique opportunity to generate animals with improved traits. In this review we discuss the techniques currently applied to genetic manipulation of livestock species and the efforts in making animals disease resistant or resilient.

Choosing a culture medium for SCNT and iSCNT reconstructed embryos: from domestic to wildlife species

Over the past decades, in vitro culture media have been developed to successfully support IVF embryo growth in a variety of species. Advanced reproductive technologies, such as somatic cell nuclear transfer (SCNT), challenge us with a new type of embryo, with special nutritional requirements and altered physiology under in vitro conditions. Numerous studies have successfully reconstructed cloned embryos of domestic animals for biomedical research and livestock production. However, studies evaluating suitable culture conditions for SCNT embryos in wildlife species are scarce (for both intra- and interspecies SCNT). Most of the existing studies derive from previous IVF work done in conventional domestic species. Extrapolation to non-domestic species presents significant challenges since we lack information on reproductive processes and embryo development in most wildlife species. Given the challenges in adapting culture media and conditions from IVF to SCNT embryos, developmental competence of SCNT embryos remains low. This review summarizes research efforts to tailor culture media to SCNT embryos and explore the different outcomes in diverse species. It will also consider how these culture media protocols have been extrapolated to wildlife species, most particularly using SCNT as a cutting-edge technical resource to assist in the preservation of endangered species.

Methodological strategies for transgene copy number quantification in goats (Capra hircus) using real-time PCR

Taking into account the importance of goats as transgenic models, as well as the rarity of copy number (CN) studies in farm animals, the present work aimed to evaluate methodological strategies for accurate and precise transgene CN quantification in goats using quantitative polymerase chain reaction (qPCR). Mouse and goat lines transgenic for human granulocyte-colony stimulating factor were used. After selecting the best genomic DNA extraction method to be applied in mouse and goat samples, intra-assay variations, accuracy and precision of CN quantifications were assessed. The optimized conditions were submitted to mathematical strategies and used to quantify CN in goat lines. The findings were as follows: validation of qPCR conditions is required, and amplification efficiency is the most important. Absolute and relative quantifications are able to produce similar results. For normalized absolute quantification, the same plasmid fragment used to generate goat lines must be mixed with wild-type goat genomic DNA, allowing the choice of an endogenous reference gene for data normalization. For relative quantifications, a resin-based genomic DNA extraction method is strongly recommended when using mouse tail tips as calibrators to avoid tissue-specific inhibitors. Efficient qPCR amplifications (≥95%) allow reliable CN measurements with SYBR technology. TaqMan must be used with caution in goats if the nucleotide sequence of the endogenous reference gene is not yet well understood. Adhering to these general guidelines can result in more exact CN determination in goats. Even when working under nonoptimal circumstances, if assays are performed that respect the minimum qPCR requirements, good estimations of transgene CN can be achieved.

In vitro production of small ruminant embryos: late improvements and further research

Beyond the potential use of in vitro production of embryos (IVP) in breeding schemes, embryos are also required for the establishment of new biotechnologies such as cloning and transgenesis. Additionally, the knowledge of oocyte and embryo physiology acquired through IVP techniques may stimulate the further development of other techniques such as marker assisted and genomic selection of preimplantation embryos, and also benefit assisted procreation in human beings. Efficient in vitro embryo production is currently a major objective for livestock industries, including small ruminants. The heterogeneity of oocytes collected from growing follicles by laparoscopic ovum pick up or in ovaries of slaughtered females, remains an enormous challenge for IVM success, and still limits the rate of embryo development. In addition, the lower quality of the IVP embryos, compared with their in vivo-derived counterparts, translates into poor cryosurvival, which restricts the wider use of this promising technology. Therefore, many studies have been reported in an attempt to determine the most suitable conditions for IVM, IVF, and in vitro development to maximize embryo production rate and quality. This review aims to present the current panorama of IVP production in small ruminants, describing important steps for its success, reporting the recent advances and also the main obstacles identified for its improvement and dissemination.

Generation of human lactoferrin transgenic cloned goats using donor cells with dual markers and a modified selection procedure

The objective was to use dual markers to accurately select genetically modified donor cells and ensure that the resulting somatic cell nuclear transfer kids born were transgenic. Fetal fibroblast cells were transfected with dual marking gene vector (pCNLF-ng) that contained the red-shifted variant of the jellyfish green fluorescent protein (LGFP) and neomycin resistance (Neo) markers. Cell clones that were G418-resistant and polymerase chain reaction-positive were subcultured for several passages; individual cells of the clones were examined with fluorescence microscopy to confirm transgenic integration. Clones in which every cell had bright green fluorescence were used as donor cells for nuclear transfer. In total, 86.7% (26/30) cell clones were confirmed to have transgenic integration of the markers by polymerase chain reaction, 76.7% (23/30) exhibited fluorescence, but only 40% (12/30) of these fluorescent cell clones had fluorescence in all cell populations. Moreover, through several cell passages, only 20% (6/30) of the cell clones exhibited stable LGFP expression. Seven transgenic cloned offspring were produced from these cells by nuclear transfer. Overall, the reconstructed embryo fusion rate was 76.6%, pregnancy rates at 35 and 60 days were 39.1% and 21.7%, respectively, and the offspring birth rate was 1.4%. There were no significant differences between nuclear transfer with dual versus a single (Neo) marker (overall, 73.8% embryo fusion rate, 53.8% and 26.9% pregnancy rates, and 1.9% birth rate with five offspring). In conclusion, the use of LGFP/Neo dual markers and an optimized selection procedure reliably screened genetically modified donor cells, excluded pseudotransgenic cells, and led to production of human lactoferrin transgenic goats. Furthermore, the LGFP/Neo markers had no adverse effects on the efficiency of somatic cell nuclear transfer.

Precision editing of large animal genomes

Transgenic animals are an important source of protein and nutrition for most humans and will play key roles in satisfying the increasing demand for food in an ever-increasing world population. The past decade has experienced a revolution in the development of methods that permit the introduction of specific alterations to complex genomes. This precision will enhance genome-based improvement of farm animals for food production. Precision genetics also will enhance the development of therapeutic biomaterials and models of human disease as resources for the development of advanced patient therapies.

Detection of endoplasmic reticulum stress markers and production enhancement treatments in transgenic goats expressing recombinant human butyrylcholinesterase

Compromised lactation physiology has been observed in transgenic animals, possibly due to the excessive demand placed by the expression of complex recombinant glycoproteins in the mammary gland. In previous studies we described lactation parameters and milk composition characteristics of transgenic goats expressing recombinant human butyrylcholinesterase in milk, and we showed evidence suggesting that lactation cessation could be associated with endoplasmic reticulum stress. We now report data from immunohistochemistry studies targeting activation transcription factor 6 and caspase 12, two signal transducers associated with endoplasmic reticulum stress, designed to further elucidate potential mechanisms responsible for the disruption in mammary epithelium function previously described. We found strong evidence of endoplasmic reticulum stress associated with the premature cessation of lactation. In addition, we utilized previously generated knowledge to design and test two treatments for enhanced productivity in transgenic goats. Pre-partum treatment with reserpine and dexamethasone to stimulate mammary priming for lactation resulted in a significant increase in milk production on day 1 (573 ± 350 vs. 93 ± 92 mL; P < 0.01), first week (8,832 ± 2,286 vs. 5,946 ± 2,039; P < 0.01) and the first month of lactation (42.5 ± 10 vs. 34.9 ± 6 kg; P < 0.05) compared to untreated controls. Mammary infusions with inosine during the early stages of lactation to promote mammary stem-cell proliferation also resulted in significantly increased milk production volumes, ranging from 26 to 200% more milk, in the treated glands compared to placebo.

Protein profile and alpha-lactalbumin concentration in the milk of standard and transgenic goats expressing recombinant human butyrylcholinesterase

The expression of recombinant proteins of pharmaceutical interest in the milk of transgenic farm animals can result in phenotypes exhibiting compromised lactation performance, as a result of the extraordinary demand placed on the mammary gland. In this study, we investigated differences in the protein composition of milk from control and transgenic goats expressing recombinant human butyrylcholinesterase. In Experiment 1, the milk was characterized by gel electrophoresis and liquid chromatography/mass spectrometry in order to identify protein bands that were uniquely visible in the transgenic milk and/or at differing band densities compared with controls. Differences in protein content were additionally evaluated by computer assisted band densitometry. Proteins identified in the transgenic milk only included serum proteins (i.e. complement component 3b, ceruloplasmin), a cytoskeleton protein (i.e. actin) and a stress-induced protein (94 kDA glucose-regulated protein). Proteins exhibiting evident differences in band density between the transgenic and control groups included immunoglobulins, serum albumin, beta-lactoglobulin and alpha-lactalbumin. These results were found to be indicative of compromised epithelial tight junctions, premature mammary cell death, and protein synthesis stress resulting from transgene expression. In Experiment 2, the concentration of alpha-lactalbumin was determined using the IDRing assay and was found to be significantly reduced on day 1 of lactation in transgenic goats (4.33 +/- 0.97 vs. 2.24 +/- 0.25 mg/ml, P < 0.01), but was not different from non-transgenic controls by day 30 (0.99 +/- 0.46 vs. 0.90 +/- 0.11 mg/ml, P > 0.05). We concluded that a decreased/delayed expression of the alpha-lactalbumin gene may be the cause for the delayed start of milk production observed in this herd of transgenic goats.

A Gag peptide encompassing B- and T-cell epitopes of the caprine arthritis encephalitis virus functions as modular carrier peptide

Short synthetic peptides are important tools in biomedical research permitting to generate hapten specific polyclonal sera for analytical purposes or functional studies. In this paper we provide proof of principle that a peptide located in a highly conserved portion of the Gag protein of the caprine arthritis encephalitis virus and carrying an immunodominant T helper cell epitope functions as an efficient carrier peptide, mediating a strong antibody response to a peptidic hapten encompassing a well-characterized B cell epitope of Env. The carrier and hapten peptides were collinearly synthesized permutating their molecular arrangement. While the antibody response to the hapten was similar for both constructs, the antibody response to a B cell epitope overlapping the T helper cell epitope of the Gag carrier peptide was considerably different. This permits a modular use of the carrier peptide to generate antibody directed exclusively to the hapten peptide or a strong humoral response to both carrier- and hapten-peptide. Finally, we have mapped the epitopes involved in this polarized antibody response and discussed the potential immunological implications.

Milk composition studies in transgenic goats expressing recombinant human butyrylcholinesterase in the mammary gland

The use of the mammary gland of transgenic goats as a bioreactor is a well established platform for the efficient production of recombinant proteins, especially for molecules that cannot be adequately produced in traditional systems using genetically engineered microorganisms and cells. However, the extraordinary demand placed on the secretory epithelium by the expression of large amounts of the recombinant protein, may result in a compromised mammary physiology. In this study, milk composition was compared between control and transgenic goats expressing high levels (1-5 g/l) of recombinant human butyrylcholinesterase in the milk. Casein concentration, as evaluated by acid precipitation, was significantly reduced in the transgenic compared with the control goats throughout lactation (P < 0.01). Milk fatty acid composition for transgenic goats, as determined by gas chromatography, was found to have significantly fewer short chain fatty acids (P < 0.01) and more saturated fatty acids (P < 0.05) compared to controls, suggesting an overall metabolic stress and/or decreased expression of key enzymes (e.g. fatty acid synthase, stearoyl-CoA desaturase). The concentration of Na(+), K(+), assessed by atomic absorption spectrophotometry, and serum albumin, determined by bromocresol green dye and scanning densitometry, were similar in transgenic and control goats during the first several weeks of lactation. However, as lactation progressed, a significant increase in Na and serum albumin concentrations and a decrease in K(+) concentration were found in the milk of transgenic goats, while control animals remained unchanged (P < 0.01). These findings suggest that: (a) high expression of recombinant proteins may be associated with a slow-down in other synthetic activities at the mammary epithelium, as evidenced by a reduced casein expression and a decreased de-novo synthesis of fatty acids; (b) the development of permeable tight junctions may be the main mechanism involved in the premature cessation of milk secretion observed in these transgenic goats.

Lactation performance of transgenic goats expressing recombinant human butyryl-cholinesterase in the milk

The production of recombinant proteins in the milk of transgenic animals has attracted significant interest in the last decade, as a valuable alternative for the production of recombinant proteins that cannot be or are inefficiently produced using conventional systems based on microorganisms or animal cells. Several recombinant proteins of pharmaceutical and biomedical interest have been successfully expressed in high quantities (g/l) in the milk of transgenic animals. However, this productivity may be associated with a compromised mammary physiology resulting, among other things, from the extraordinary demand placed on the mammary secretory cells. In this study we evaluated the lactation performance of a herd of 50 transgenic goats expressing recombinant human butyryl-cholinesterase (rBChE) in the milk. Our findings indicate that high expression levels of rBChE (range 1-5 g/l) are produced in these animals at the expense of an impaired lactation performance. The key features characterizing these transgenic performances were the decreased milk production, the reduced milk fat content which was associated with an apparent disruption in the lipid secretory mechanism at the mammary epithelium level, and a highly increased presence of leukocytes in milk which is not associated with mammary infection. Despite of having a compromised lactation performance, the amount of rBChE produced per transgenic goat represents several orders of magnitude more than the amount of rBChE present in the blood of hundreds of human donors, the only other available source of rBChE for pharmaceutical and biodefense applications. As a result, this development constitutes another successful example in the application of transgenic animal technology.

Purification of transgenic plant-derived recombinant human acetylcholinesterase-R

Nicotiana benthamiana plants were engineered to express a codon-optimized gene encoding the human acetylcholinesterase-R (AChE) isoform. The transgenic plants expressed the protein at >0.4% of total soluble protein, and the plant-produced enzyme was purified to homogeneity. Following lysis, procainamide affinity chromatography and anion-exchange chromatography, more than 400-fold purification was achieved and electrophoretic purity was obtained. This pure protein is kinetically indistinguishable from the only commercially available source of human acetylcholinesterase, which is produced in mammalian cell culture. Thus, we have demonstrated a model system for the production of acetylcholinesterase, which is not susceptible to the quantitative limitations or mammalian pathogens associated with purification from mammalian cell culture or human serum.

Health and reproductive profiles of malaria antigen-producing transgenic goats derived by somatic cell nuclear transfer

Nuclear transfer (NT) using transfected primary cells is an efficient approach for the generation of transgenic goats. However, reprogramming abnormalities associated with this process might result in compromised animals. We examined the health, reproductive performance, and milk production of four transgenic does derived from somatic cell NT. Goats were derived from two fetal cell lines, each transfected with a transgene expressing a different version of the MSP-1(42) malaria antigen, either glycosylated or non-glycosylated. Two female kids were produced per cell line. Health and growth of these NT animals were monitored and compared with four age-matched control does. There were no differences in birth and weaning weights between NT and control animals. The NT does were bred and produced a total of nine kids. The control does delivered five kids. The NT does expressing the glycosylated antigen lactated only briefly, probably as a result of over-expression of the MSP-1(42) protein. However, NT does expressing the non-glycosylated antigen had normal milk yields and produced the recombinant protein. These data demonstrated that the production of healthy transgenic founder goats by somatic cell NT is readily achievable and that these animals can be used successfully for the production of a candidate Malaria vaccine.

Update on reproductive biotechnologies in small ruminants and camelids

Recent advances in reproductive biotechnologies in small ruminants include improvement of methods for in vitro production of embryos and attempts at spermatogonial stem cell transplantation. In vitro production of embryos by IVM/IVF, intra-cytoplasmic sperm injection (ICSI), or nuclear transfer (NT) has been made possible by improvements in oocyte collection and maturation techniques, and early embryo culture systems. However, in vitro embryo production still is not very efficient due to several limiting factors affecting the outcome of each step of the process. This paper discusses factors affecting in vitro embryo production in small ruminants and camelids, as well as preliminary results with the technique of spermatogonial stem cell transplantation.

Advanced assisted reproduction technologies (ART) in goats

Assisted reproduction technologies (ART) are reviewed with special emphasis on goat genetic improvement programs. Estrous synchronization and artificial insemination are the most commonly used ART worldwide because of their simplicity and excellent cost/benefit, especially when proven sires are used. Multiple ovulation and embryo transfer (MOET) has not become widely used due to its unpredictability. In vitro embryo production using oocytes collected by laparoscopy from valuable donors has the potential to improve the results obtained from MOET and expand its applications (for example, using prepubertal donors). However, the costs and inefficiencies of the system might restrict its use to special situations. Finally, transgenesis and cloning are expected to have a significant impact on the future genetic improvement of livestock. However, because of low efficiencies and high costs, their present use is restricted to applications with high returns such as the production of recombinant proteins of pharmaceutical and biomedical interest.