Transgenic goats produced by DNA pronuclear microinjection of in vitro derived zygotes

In vitro culture of reptile PGCS to preserve endangered species

Primordial germ cells (PGCs), are the source of gametes in vertebrates. There are similarities in the development of PGCs of reptiles with avian and mammalian species PGCs development. PGCs culture has been performed for avian and mammalian species but there is no report for reptilian PGCs culture. In vitro culture of PGCs is needed to produce transgenic animals, preservation of endangered animals and for studies on cell behaviour and research on fertility. Reptiles are traded as exotic pets and a source of food and they are valuable for their skin and they are useful as model for medical research. Transgenic reptile has been suggested to be useful for pet industry and medical research. In this research different aspects of PGCs development was compared in three main classes of vertebrates including mammalian, avian and reptilian species. It is proposed that a discussion on similarities between reptilian PGCs development with avian and mammalian species helps to find clues for studies of reptilian PGCs development details and finding an efficient protocol for in vitro culture of reptilian PG.

Green Composites Based on Animal Fiber and Their Applications for a Sustainable Future

Global climate change is already affecting the environment, as glaciers are receding, ice on rivers and lakes is melting, plant and animal range`s have altering, and trees are blooming early. Therefore, focus has shifted towards sustainable materials. There is a growing desire for materials that have a unique combination of qualities that metals, polymers, and other materials cannot provide, therefore scientists are turning their focus to green composites. Green composites offer a wide range of uses in automotive, aerospace, and marine applications. Composites are multiphase resources with separate interfaces that contain chemically different materials. Composites are made up of a variety of materials that are distinct in nature, and they give a set of desirable features that are superior to those of their predecessors or parents. Natural fibers are less expensive, more readily available, rust-resistant, plentiful, nontoxic, and safe for human skin, eyes, and respiratory systems. Green composites are created by combining renewable fibers with polymers (matrix) to create a new class of composites known as "green composites." This review includes studies on various animal-based fibers and their applications. In this article, recent advancements in the field of these fibers and their composites of fibers are also discussed. The physical, chemical, and mechanical properties are also discussed in this paper. Moreover, the benefits and drawbacks of using these fibers are also discussed in detail. Finally, the paper gives an outline of the topic. The results from composites constructed from each fiber are provided, along with appropriate references for more in-depth analysis studies. This review is specially performed to strengthen the knowledge bank of the young researchers working in the field of natural composites.

Laparoscopic Ovum Pick-Up Followed by In Vitro Embryo Production and Transfer in Assisted Breeding Programs for Ruminants

The potential of laparoscopic ovum pick-up (LOPU) followed by in vitro embryo production (IVEP) as a tool for accelerated genetic programs in ruminants is reviewed in this article. In sheep and goats, the LOPU-IVEP platform offers the possibility of producing more offspring from elite females, as the procedure is minimally invasive and can be repeated more times and more frequently in the same animals compared with conventional surgical embryo recovery. On average, ~10 and ~14 viable oocytes are recovered by LOPU from sheep and goats, respectively, which results in 3-5 transferable embryos and >50% pregnancy rate after transfer. LOPU-IVEP has also been applied to prepubertal ruminants of 2-6 months of age, including bovine and buffalo calves. In dairy cattle, the technology has gained momentum in the past few years stemming from the development of genetic marker selection that has allowed predicting the production phenotype of dairy females from shortly after birth. In Holstein calves, we obtained an average of ~22 viable oocytes and ~20% transferable blastocyst rate, followed by >50% pregnancy rate after transfer, declaring the platform ready for commercial application. The present and future of this technology are discussed with a focus on improvements and research needed.

L-OPU in Goat and Sheep-Different Variants of the Oocyte Recovery Method

Simple summary

In this study, minimally invasive laparoscopic methods of recovering oocytes in goat and sheep (L-OPU, laparoscopic ovum pick-up) were developed and improved. Applying the laparoscopic technique allows animal welfare to be significantly improved while still maintaining high effectiveness of the method. The method allows a high number of good quality oocytes to be obtained and additionally reduces the invasiveness of the method and tissue damage which occurs during the operation to a minimum. It requires a short time and allows animals to return to the herd immediately after the operation has been completed. Additionally, it also gives the opportunity for maximum use of the animal’s genetic capability. The limitation of using the L-OPU method in goats is its variable and changing effectiveness. That is why it is crucial to develop an effective and repeatable method. The study compared several variants of the method including varying techniques of conducting the operation, various tools for recovering oocytes, and different plans of hormonal stimulation. As a result, an optimal method of recovering oocytes was developed. The research may be of great importance in improving the welfare of animals and increasing the effectiveness of biotechnological methods used in goat and sheep breeding as well as in the area of research.

Abstract

The laparoscopic method of recovering oocytes in goats and sheep is one of the minimally invasive methods used in the biotechnology of animal reproduction. It allows for good quality oocytes that are suitable for in vitro maturation and fertilization to be recovered. The limitation of using the laparoscopic ovum pick-up (L-OPU) method in goat and sheep is its changing effectiveness and the lack of repeatability of results, as well as the varying effectiveness of different variants of the method. Therefore, it is necessary to develop effective non-invasive techniques allowing for multiple good quality oocyte recovery that would be suitable for in vitro maturation and fertilization. In this study, four different L-OPU variants were described in goats and sheep. Various techniques of recovering oocytes were discussed, including the techniques of conducting the operation, various tools for recovering oocytes, and different plans of hormonal stimulation. Recovery rates were 35% (Variant I), 57% (Variant II), 72% (Variant III), and 67% (Variant IV). After evaluation, 94% (both Variant I and II), 93% (Variant III), and 84% (Variant IV) of the oocytes were qualified for in vitro maturation. The results of the study show that the proposed technique of laparoscopic recovery of oocytes allows a sufficient number of ovarian cells suitable for in vitro culture to be obtained and as a consequence it makes them useful in in vitro maturation/in vitro fertilization (IVM/IVF) programs or cloning. The method allows for a fast and effective conduct of the operation in a living donor with minimal invasiveness while preserving the excellent condition of animals.

AANAT transgenic sheep generated via OPS vitrified-microinjected pronuclear embryos and reproduction efficiency of the transgenic offspring

Background

The open pulled straw (OPS) vitrification method has been successfully applied in mouse, pig, and goat embryos as well as in buffalo oocytes, but it has not yet been applied to the microinjected embryos. This study examined the effects of OPS vitrification on embryo development and the reproductive capacity of the transgenic offspring in order to establish a method for preservation of microinjected embryos.

Methods

Ovine pronuclear embryos were microinjected with the exogenous aralkylamine N-acetyltransferase gene (AANAT), frozen by the OPS method, and subsequently thawed for embryo transplantation. Pregnancy rate, lambing rate, survival rate, average birth weight and transgenic positive rate as well as reproduction efficiency and hormone level of the transgenic offspring were investigated to analyze the effect of OPS vitrification on microinjectd pronuclear embryos.

Results

No significant differences were observed in the birth rate, lamb survival rate and transgenic positive rate between the frozen and non-frozen AANAT-microinjected pronuclear embryos. The average birth weight of the frozen embryos offspring was greater than that of the non-frozen embryos. Importantly, the transgenic offspring that overexpressed the AANAT gene showed improved ovulation efficiency and lambing rate by regulating their hormone levels.

Conclusions

The OPS vitrification approach may be a valuable method in microinjected- embryo transfer technology, which could reserve embryos and result in fewer unnecessary animal sacrifices. In addition, the AANAT+ transgenic offspring exhibited improved reproductive capacity on account of regulation effect of melatonin on reproductive hormone. These data may provide available references for human-assisted reproduction.

An AANAT/ASMT transgenic animal model constructed with CRISPR/Cas9 system serving as the mammary gland bioreactor to produce melatonin-enriched milk in sheep

Melatonin as a potent antioxidant exhibits important nutritional and medicinal values. To produce melatonin-enriched milk will benefit the consumers. In this study, a sheep bioreactor which generates melatonin-enriched milk has been successfully developed by the technology that combined CRISPR/Cas9 system and microinjection. The AANAT and ASMT were cloned from pineal gland of Dorper sheep (Ovis aries). The in vitro studies found that AANAT and ASMT were successfully transferred to the mammary epithelial cell lines and significantly increased melatonin production in the culture medium compared to the nontransgenic cell lines. In addition, the Cas9 mRNA, sgRNA, and the linearized vectors pBC1-AANAT and pBC1-ASMT were co-injected into the cytoplasm of pronuclear embryos which were implanted into ewes by oviducts transferring. Thirty-four transgenic sheep were generated with the transgenic positive rate being roughly 35% which were identified by Southern blot and sequencing. Seven carried transgenic AANAT, two carried ASMT, and 25 carried both of AANAT and ASMT genes. RT-PCR and Western blot demonstrated that the lambs expressed these genes in their mammary epithelial cells and these animals produced melatonin-enriched milk. This is the first report to show a functional AANAT and ASMT transgenic animal model which produce significantly high levels of melatonin milk compared to their wild-type counterparts. The advanced technologies used in the study laid a foundation for generating large transgenic livestock, for example, the cows, which can produce high level of melatonin milk.

Efficient production of pronuclear embryos in breeding and nonbreeding season for generating transgenic sheep overexpressing TLR4

BACKGROUND

Brucella is a zoonotic Gram-negative pathogen that causes abortion and infertility in ruminants and humans. TLR4 is the receptor for LPS which can recognize Brucella and initiate antigen-presenting cell activities that affect both innate and adaptive immunity. Consequently, transgenic sheep over-expressing TLR4 are an suitable model to investigate the effects of TLR4 on preventing Brucellosis. In this study, we generated transgenic sheep overexpressing TLR4 and aimed to evaluate the effects of different seasons (breeding and non-breeding season) on superovulation and the imported exogenous gene on growth.

RESULTS

In total of 43 donor ewes and 166 recipient ewes in breeding season, 37 donor ewes and 144 recipient ewes in non-breeding season were selected for super-ovulation and injected embryo transfer to generate transgenic sheep. Our results indicated the no. of embryos recovered of donors and the rate of pronuclear embryos did not show any significant difference between breeding and non-breeding seasons (P > 0.05). The positive rate of exogenous TLR4 tested were 21.21 % and 22.58 % in breeding and non-breeding season by Southern blot. The expression level of TLR4 in the transgenic sheep was 1.5 times higher than in the non-transgenic group (P < 0.05). The lambs overexpressing TLR4 had similar growth performance with non-transgenic lambs, and the blood physiological parameters of transgenic and non-transgenic were both in the normal range and did not show any difference.

CONCLUSIONS

Here we establish an efficient platform for the production of transgenic sheep by the microinjection of pronuclear embryos during the whole year. The over-expression of TLR4 had no adverse effect on the growth of the sheep.

Current status of in vitro embryo production in sheep and goats

Sheep and goat production is an important economic activity in Spain with an increasing interest in milk production. Multiovulation and Embryo Transfer (MOET) and In vitro Embryo Production (IVEP) are assisted reproductive technologies aimed at increasing the genetic diffusion of females. In vitro embryo production is a multi-step methodology comprising the following procedures: (i) In vitro Maturation (IVM) of oocytes recovered directly from the follicles, (ii) In vitro Fertilization (IVF) or co-incubation of capacitated spermatozoa with in vitro matured oocytes and (iii) In vitro culture (IVC) of zygotes up to the blastocyst stage. In vitro embryo production from oocytes recovered from prepubertal females is called JIVET (Juvenile in vitro Embryo Transfer) and allows shortened generation intervals and increased genetic gain. Embryo production together with embryo cryoconservation would allow large-scale embryo marketing, a pathogen-free genetic movement and easier and cheaper germplasm commercial transactions. Commercial Embryo activity in small ruminants is low compared to cows in the European Union (data from the European Embryo Transfer Association) and in the world (data from the International Embryo Transfer Association). There is less IVEP research in small ruminants compared to other livestock species. The aim of this review was to provide an overview of the current status of IVEP of small ruminant with an emphasis on (i) description of the main methodologies currently used for IVM, IVF and IVC of embryos (ii) comparing procedures and outputs from JIVET and IVEP of adult females and (iii) the future research perspectives of this technology.

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.

Reproductive efficiency of adult and prepubertal goats subjected to repeated follicular aspiration

The objective of this study was to assess the reproductive response of adult and prepubertal goats subjected to repeated laparoscopic ovum pick-up (LOPU). The study animals were divided into two groups, specifically, adult nanny goats (GA, n=10) and prepubertal nanny goats (GP, n=10), which were subjected to estrous synchronization and ovarian stimulation for LOPU. Both groups underwent six LOPU procedures at seven-day intervals and were subsequently subjected to controlled mating and pregnancy diagnosis to evaluate their future fertility. The study showed a reduction in the number of follicles visualized and in the amount and quality of the oocytes that were recovered and exposed to in vitro maturation. As indicated by the fertility test, however, no complications were found during the laparoscopic procedures that would impair the reproductive future of the animals. Therefore, a viable number of oocytes were obtained even with the decreased reproductive efficiency, proving that repeated LOPUs do not interfere with the reproductive of adult and prepubertal nanny goats. These results indicate a positive aspect of this procedure, allowing for increasing reproductive performance of this kind, when used for the production in vitro.

In vitro maturation and fertilization of prepubertal and pubertal black Bengal goat oocytes

Oocytes retrieval, in vitro maturation (IVM) and fertilization (IVF) efficiency are inevitable steps towards in vitro production of embryos. In the present study, these parameters were investigated in the ovaries of prepubertal (n = 31) and pubertal (n = 61) black Bengal goats obtained from a slaughterhouse. Nuclear maturation was evaluated upon aspiration and following IVM in TCM-199 (Earle's salt with L-glutamine and sodium bicarbonate) for 27 h at 39℃ under 5% CO₂ in humidified air. The oocytes retrieval and efficiency (mean ± SD) per prepubertal and pubertal goats were 5.2 ± 0.6 and 6.8 ± 0.6, and 77.3 ± 0.1% and 80.5 ± 0.6%, respectively. Anaphase I - telophase I stages differed significantly (7.3 ± 0.8 vs. 2.6 ± 0.2, p < 0.05) between the two groups of goats. After IVM, the percentages of metaphase II were significantly higher (66.3 vs. 60.3, p < 0.05) in pubertal goats than in their prepubertal counterparts. The percentages of normal in vitro fertilization (IVF) in Fert-Tyrode's albumin lactate pyruvate of pubertal goat oocytes did not differ between Percoll and swim-up sperm separation methods (36.7 ± 0.9% vs. 32.7 ± 1.3%, p > 0.05). Furthermore, sperm capacitation by heparin alone or in combination with ionomycin did not lead to a significant increase in the normal fertilization rate (34.8 ± 1.7 vs. 32.2 ± 1.5%, respectively) in the oocytes of pubertal goats. In conclusion, the ovaries of pubertal black Bengal goats obtained from the slaughterhouse could be used for in vitro embryo production. However, further optimization of the IVM and IVF techniques are necessary for satisfactory in vitro embryo production.

Laparoscopy vs. laparotomy for embryo transfer to produce transgenic goats (Capra hircus)

This study was performed to produce transgenic Korean native goat (Capra hircus) by laparoscopic embryo transfer (ET) to overcome the limitations of ET performed by laparotomy. Transgenic embryos were produced by DNA pronuclear microinjection of in vivo zygotes. The recipient goats were synchronized for estrus by using an introvaginal progesterone devices as a controlled internal drug-releasing insert (CIDR) for 13 days and injection of 400 IU PMSG 48 h before removal of the insert. Embryos were transferred on day 3 and 4 after removal of the insert. Recipient goats were deprived of feed for 48 h, then suspended in a laparotomy cradle at an angle of 45°. After obtaining a sufficient pneumoperitoneum, the laparoscope and forceps were inserted abdominally through 5 mm trocar sleeves. Examination of the ovaries and uterus was performed and then 213 embryos were transferred into the oviducts via the infundibula of 76 recipient goats. To compare pregnancy rates, ET was also performed by laparotomy in 82 recipient goats. The pregnancies in the recipient goats were diagnosed by ultrasound on day 30 after embryo transfer. The pregnancy rate with laparoscopic ET was significantly higher than with ET performed by laparotomy (46.1% vs. 28.6%, p < 0.05). In addition, the pregnancy rates were compared between ovulated and non-ovulated ovaries of the recipient goats in the laparoscopic ET group. No significant difference was observed between the pregnancy rates of ovulated and non-ovulated ovaries (41.3% vs. 33.3%, p < 0.05) suggesting that ET may also be possible in non-ovulated recipients through artificial rupture of Graafian follicles. These results suggest that laparoscopic ET is a highly efficient method for the transfer of goat embryos.

Total RNA and protein content, Cyclin B1 expression and developmental competence of prepubertal goat oocytes

The aim of this study was to examine the relationship between the developmental competence of oocytes and their total RNA and protein contents, and the level of Cyclin B1 transcription. Ovaries from prepubertal goats were collected from a slaughterhouse. Oocytes were recovered by slicing and those with two or more layers of cumulus cells and homogenous cytoplasm were matured in vitro (20-25 oocytes per drop) for 27 h. Both before and after IVM, samples of oocytes were denuded and categorised into four group treatments by diameter (<110 microm, 110-125 microm, 125-135 microm; >135 microm), separated into sub-groups of 10 oocytes per treatment-replicate and stored in liquid nitrogen until total RNA content analysis by spectophotometry, total protein content analysis by a colorimetric assay and Cyclin B1 transcription analysis by RT-PCR. For the study of developmental competence, the rest of the matured oocytes were fertilised in vitro in groups of 20-25 for 24 h. Presumptive zygotes were denuded, sorted into the four categories of diameter noted above, and placed into culture drops in groups of 18-25 for in vitro culture. Cleavage rate was evaluated at 48 hpi and embryo development at 8 d post-insemination. There were four replicates of each treatment for each assay or evaluation point of the experiment. There were no significant differences between the size categories of oocytes at collection in total RNA content, total protein content and Cyclin B1 mRNA. There were significant differences (P<0.05) in the expression of Cyclin B1 before IVM with oocytes in the >135 mm diameter category having the highest value for this variant. There were no significant differences in these characteristics between the categories of oocyte diameter after IVM except in respect of total RNA content, which was lower for the largest size of oocytes (>135 microm; mean+/-S.D.=12.3+/-1.84 ng/oocyte) than the other three size groups (19.2+/-1.38-22.1+/-4.44 ng/oocyte; P<0.05). Significant differences (P<0.05) in cleavage rate were observed between the different oocyte size categories (<110 microm, 3.0%; 110-125 microm, 32%; 125-135 microm, 50%; >135 microm, 73%). Only oocytes >125 microm diameter developed to the blastocyst stage (125-135 microm, 7%; >135 microm, 10%). This study showed that the RNA content and the Cyclin B1 RNA expression of prepubertal goat oocytes, and their development to embryos varied between the different size categories of the oocytes.

Production of transgenic goat (Capra hircus) with human Granulocyte Colony Stimulating Factor (hG-CSF) gene in Brazil

In order to produce transgenic goats with hG-CSF, a total of 24 adult Saanen and 48 adult undefined breed goats were used as donors and recipients, respectively. Donors were estrus-synchronized with vaginal sponges and superovulated by a treatment with 200 mg FSH given twice daily in decreasing doses over 3 days starting 48 h before sponge removal. Ovulation was induced by injecting 100 microg GnRH 36 h after sponge removal. The recipients also received an estrus synchronization treatment. Donors were mated with fertile Saanen bucks and, approximately 72 h after sponge removal, zygotes were recovered surgically by flushing oviducts. The recovered zygotes were briefly centrifuged to a reliable visualization of the pronuclei. The DNA construct containing hG-CSF gene flanked by goat and bovine alphas1-casein sequences was injected into pronuclei of 129 zygotes. The microinjected embryos (3-6 per female) were transferred to 27 recipients. Ten recipients became pregnant and 12 kids were born. One transgenic male founder was identified in the group of kids. This is the first report of a birth of a transgenic goat in Latin America.

Recombinant human butyrylcholinesterase from milk of transgenic animals to protect against organophosphate poisoning

Dangerous organophosphorus (OP) compounds have been used as insecticides in agriculture and in chemical warfare. Because exposure to OP could create a danger for humans in the future, butyrylcholinesterase (BChE) has been developed for prophylaxis to these chemicals. Because it is impractical to obtain sufficient quantities of plasma BChE to treat humans exposed to OP agents, the production of recombinant BChE (rBChE) in milk of transgenic animals was investigated. Transgenic mice and goats were generated with human BChE cDNA under control of the goat beta-casein promoter. Milk from transgenic animals contained 0.1-5 g/liter of active rBChE. The plasma half-life of PEGylated, goat-derived, purified rBChE in guinea pigs was 7-fold longer than non-PEGylated dimers. The rBChE from transgenic mice was inhibited by nerve agents at a 1:1 molar ratio. Transgenic goats produced active rBChE in milk sufficient for prophylaxis of humans at risk for exposure to OP agents.

Effect of oocyte diameter on meiotic competence, embryo development, p34 (cdc2) expression and MPF activity in prepubertal goat oocytes

The aim of this study was to analyze the relationship between oocyte diameter, meiotic and embryo developmental competence and the expression of the catalytic subunit of MPF, the p34(cdc2), at mRNA, RNA and protein level, as well as its kinase activity, in prepubertal (1-2 months old) goat oocytes. MPF is the main meiotic regulator and a possible regulator of cytoplasmic maturation; therefore, it could be a key factor in understanding the differences between competent and incompetent oocytes. Oocytes were classified according to oocyte diameter in four categories: <110, 110-125, 125-135 and >135 microm and matured, fertilized and cultured in vitro. The p34(cdc2) was analyzed in oocytes at the time of collection (0 h) and after 27 h of IVM (27 h) in each of the oocyte diameter categories. The oocyte diameter was positively related to the percentage of oocytes at MII after IVM (0, 20.7, 58 and 78%, respectively) and the percentage of blastocysts obtained at 8 days postinsemination (0, 0, 1.95 and 12.5%, respectively). The expression of RNA and mRNA p34(cdc2) did not vary between oocyte diameters at 0 and 27h. Protein expression of p34(cdc2) increased in each oocyte category after 27 h of maturation. MPF activity among diameter groups did not vary at 0h but after IVM there was a clear and statistically significant increase of MPF activity in the biggest oocytes.

Embryo development of prepubertal goat oocytes fertilised by intracytoplasmic sperm injection (ICSI) according to oocyte diameter

The aim of this study was to evaluate embryo development of prepubertal goat oocytes fertilised by ICSI according to their diameter. Three experiments were carried out to achieve this objective. In all experiments, oocytes were matured in TCM199 supplemented with hormones, cysteamine and serum for 27 h at 38.5 degrees C. In Experiment 1, we studied the nuclear stage of goat zygotes produced by conventional ICSI and IVF using 20 nM ionomycin plus 10 microM heparin as sperm treatment. A group of Sham-injected oocytes was used as control. Results showed differences in the percentage of 2 PN (zygotes with male and female pronuclei) between ICSI, IVF and Sham (40.9, 26.6 and 3.0%, respectively; P<0.05). In Experiment 2, we evaluated the embryo development of prepubertal goat oocytes produced by ICSI and IVF after 192 h of culture in SOF medium. The percentage of morulae plus blastocysts obtained was higher in the ICSI than in the IVF group (13.4 and 5.1%, respectively; P<0.05). In Experiment 3, IVM-oocytes were classified in four groups depending on their diameter (Group A: <110 microm; Group B: 110-125 microm; Group C: 125-135 microm; Group D: >135 microm), fertilised by ICSI and cultured for 192 h. Results showed a positive correlation between oocyte diameter and embryo development (morulae+blastocysts: Group A: 0%; Group B: 6.2%; Group C: 46.4% and Group D: 33.3%). In conclusion, sperm treatment with ionomycin plus heparin using the conventional ICSI protocol improved fertilisation rates in comparison to IVF. Oocytes smaller than 125 microm were unable to develop up to blastocyst stage.

Effect of roscovitine on nuclear maturation, MPF and MAP kinase activity and embryo development of prepubertal goat oocytes

The low number of embryos obtained from IVM-IVF-IVC of prepubertal goat oocytes could be due to an incomplete cytoplasmic maturation. Roscovitine (ROS) inhibits MPF and MAP kinase activity and maintains the oocyte at Germinal Vesicle (GV) stage. The aim of this study was to determine if meiotic activity is arrested in prepubertal goat oocytes cultured with 0, 12.5, 25, 50 and 100 microM of ROS for 24 h. A group of oocytes from adult goats was cultured with 25 microM of ROS to compare the effect of ROS on prepubertal and adult goat oocytes. A sample of oocytes was stained to evaluate the nuclear stage at oocyte collection time and after ROS incubation. IVM-oocytes not exposed to ROS formed the control group. Prepubertal goat IVM-oocytes were inseminated and cultured for 8 days. The percentage of oocytes at GV stage, after exposition to ROS was significantly higher in adult goat oocytes (64.5%) than in prepubertal goat oocytes. No differences were found among 25, 50 and 100 microM ROS concentrations (29, 23 and 26%, oocytes at GV stage, respectively). After 8 days of culture, no differences in total embryos were observed between control oocytes and oocytes treated with 12.5 and 25 microM (45.2, 36.1 and 39.4%, respectively), however the percentage of blastocysts was higher in the control group. Western blot for the MAPK and p34(cdc2) showed that both enzymes were active in prepubertal goat oocytes after 24h of ROS exposition. In conclusion, a low percentage of prepubertal goat oocytes reached GV stage after ROS incubation; possibly because most of them had reinitiated the meiosis inside the follicle. ROS did not affect fertilization or total embryos but ROS showed a negative effect on blastocyst development.

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.

Effect of donor stimulation, frozen semen and heparin treatment on the efficiency of in vitro embryo production in goats

Investigations on in vitro embryo production in goats in comparison with other domestic species, especially cattle, have been the subject of few reports despite their usefulness for both basic research and commercial application. The objectives of this study were to compare the efficiency of IVP in goats using immature follicular oocytes recovered from FSH-primed and control goats. After IVM, oocytes were fertilized with fresh or frozen-thawed semen capacitated with or without heparin. Mature oocytes were fertilized in vitro with fresh and frozen-thawed sperm of a single buck. Sperm preparation included swim-up separation and heparin treatment (50 micrograms/ml of sperm suspension for 45 min) before spermatozoa were added to oocytes in TALP-IVF. After IVF, the zygotes were cultured for 24h and cleaved embryos were further cultured with goat oviduct epithelial cells or transferred to synchronized recipients. Mean number of oocytes recovered from FSH-primed goats (24.5 +/- 8.6) was significantly higher (P < 0.01; t test) in comparison to control does (14.7 +/- 4.7). Irrespective of fresh or frozen semen, no differences were observed in blastocyst yield when sperm was treated with heparin. However, the highest cleavage rate (99/126; 79.4%) as well as blastocyst yield (47/126; 37.3%) was obtained after IVF with fresh sperm capacitated without heparin. Contrary to fresh sperm, heparin treatment of frozen-thawed sperm significantly improved (P < 0.01) embryo cleavage. No differences between in vivo developmental competence of embryos related to sperm origin were found after transferring into recipients. Overall, more than 60% of the recipients became pregnant and 20% of all transferred embryos survived delivering 13 healthy kids. Our caprine IVP system allows obtaining embryos with developmental competence comparable to bovine IVP.

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.

Developmental competence of heifer oocytes selected using the brilliant cresyl blue (BCB) test

The aim of this study was to evaluate the usefulness of the brilliant cresyl blue (BCB) test in the selection of more competent heifer oocytes for in vitro embryo production (IVEP). IVEP from selected BCB heifer oocytes was compared to IVEP from morphologically selected heifer (control group) and cow oocytes. BCB staining determines the activity of glucose-6-phosphate dehydrogenase (G6PD), an enzyme synthesized in growing oocytes but with less activity in grown oocytes. Six hundred and fifty seven heifer cumulus-oocyte complexes (COC) were classified morphologically as Grade 1-3 and exposed to 26 microM of BCB and classified as: blue (or grown) oocytes (BCB+) or unstained oocytes or growing oocytes (BCB-). Grade 1-3 heifer oocytes showed significantly different percentages of BCB+ oocytes (78.6, 66.2, and 51.1%, respectively; P<0.05). The diameter of BCB+ oocytes was significantly higher than BCB- oocytes (152.6+/-5.8 microm and 147+/-5.9 microm, respectively; P<0.001). The percentage of BCB+ oocytes reaching the blastocyst stage was significantly higher than those of BCB- and control heifer oocytes (12.3, 1.6, and 5.2%, respectively; P<0.05), but lower than those of cow oocytes (30.0%; P<0.05). In conclusion, heifer oocytes selected by the BCB test (BCB+) are larger and more competent for IVEP than control heifer oocytes. However, fewer heifer oocytes selected using the BCB test develop to blastocyst stage compared to cow oocytes.

State-of-the-art production, conservation and transfer of in-vitro-produced embryos in small ruminants

Today, although not efficient enough to replace multiple ovulation and embryo transfer, in vitro embryo production for small ruminants is a platform for new reproductive technologies, such as embryo sexing, transgenesis and cloning. The in vitro embryo-production system developed for sheep and goats is more efficient now than 15 years ago, but could still be improved. Laparoscopic collection of oocytes in live animals treated with gonadotrophin indicates a promising future for the application of this technology to genetic improvement programmes. Oocyte maturation in defined medium with epidermal growth factor and cysteamine appears as efficient as oocyte maturation in follicular fluid-supplemented medium and allows future study of the effect of other factors involved in the cytoplasmic maturation of oocytes from these species. Further efforts have to be made to standardise the semen-capacitating process and to improve the quality and freezability of in-vitro-produced (IVP) embryos. The optimisation of IVP procedures for deer species has required the study of the seasonal variation of oocyte competence and the development of a specific methodology to allow the culture of embryos up to the blastocyst stage.

State of the art in the production of transgenic goats

This review summarises recent advances in the field of transgenic goats for the purpose of producing recombinant proteins in their milk. Production of transgenic goats via pronuclear microinjection of DNA expression vectors has been the traditional method, but this results in low efficiencies. Somatic cell nuclear transfer has dramatically improved efficiencies in rates of transgenesis. Characterisation of transfected cells in vitro before use in nuclear transfer guarantees that kids born are transgenic and of predetermined gender. Using these platform technologies, several recombinant proteins of commercial interest have been produced, although none of them has yet gained marketing approval. Before these technologies are implemented in goat improvement programmes, efficiencies must be improved, costs reduced, and regulatory approval obtained for the marketing of food products derived from such animals.