Artificial insemination and the assisted reproductive technologies in non-human primates

The experience with artificial insemination (AI) and the more invasive ARTs (assisted reproductive technologies) in the propagation of non-human primates (NHPs), although limited, has included representation from the Great Apes and both Old World and New World Macaques. The application of these technologies in NHPs is impacted by high cost, substantial technical requirements and the limited captive populations of available animals. A major incentive for their use would be to propagate endangered, underrepresented individuals or valuable founder animals. Detailed protocols and a substantial experience base for the ARTs are available for rhesus and cynomolgus macaques and form the basis of this review, including sperm recovery, processing and long-term storage at low temperatures, insemination techniques and timing. Controlled ovarian stimulation and subsequent oocyte recovery required for the invasive ARTs such as intracytoplasmic sperm injection (ICSI), is also described. Three recent AI reports in Old World Macaques are reviewed, along with examples of the use of the ARTs in the propagation of valuable founder animals, in the preservation of endangered macaques, and finally in the creation of neurodegenerative disease models for biomedical research purposes.

Reprogramming following somatic cell nuclear transfer in primates is dependent upon nuclear remodeling

BACKGROUND

Somatic cell nuclear transfer (SCNT) requires cytoplast-mediated reprogramming of the donor nucleus. Cytoplast factors such as maturation promoting factor are implicated based on their involvement in nuclear envelope breakdown (NEBD) and premature chromosome condensation (PCC). Given prior difficulties in SCNT in primates using conventional protocols, we hypothesized that the ability of cytoplasts to induce nuclear remodeling was instrumental in efficient reprogramming.

METHODS

NEBD and PCC in monkey (Macaca mulatta) SCNT embryos were monitored by lamin A/C immunolabeling.

RESULTS

Initially, a persistent lamin A/C signal from donor cell nuclei after fusion with cytoplasts was observed indicative of incomplete NEBD following SCNT and predictive of developmental arrest. We then identified fluorochrome-assisted enucleation and donor cell electrofusion as likely candidates for inducing premature cytoplast activation and a consequent lack of nuclear remodeling. Modified protocols designed to prevent premature cytoplast activation during SCNT showed robust NEBD and PCC. Coincidently, over 20% of SCNT embryos reconstructed with fetal fibroblasts progressed to blastocysts. Similar results were obtained with other somatic cells. Reconstructed blastocysts displayed patterns of Oct-4 expression similar to fertilized embryos reflecting successful reprogramming.

CONCLUSIONS

Our results represent a significant breakthrough in elucidating the role of nuclear remodeling events in reprogramming following SCNT.

A comparative approach to somatic cell nuclear transfer in the rhesus monkey

BACKGROUND

Despite the potential utility of primate somatic cell nuclear transfer (SCNT) to biomedical research and to the production of autologous embryonic stem (ES) cells for cell- or tissue-based therapy, a reliable method for SCNT is not yet available. Employing the rhesus monkey as a clinically relevant animal model, we have compared a conventional electrofusion method for SCNT with a one-step micromanipulation (OSM) method.

METHODS

A prospective, randomized trial was conducted using only oocytes that were mature [metaphase II (MII)] at collection and a fibroblast-like cell line as nuclear donor cells (fetal fibroblasts). The embryos produced were characterized for in vitro developmental potential, cell number, karyotype and expression of nuclear mitotic apparatus (NuMA) and OCT-4.

RESULTS

An in vitro blastocyst development rate of 24.4% was achieved with the OSM method, significantly higher than the 12.2% obtained following electrofusion. SCNT-produced embryos expressed normal karyotypes, cell numbers and NuMA and OCT-4 proteins in most cases. SCNT with male nuclear donor cells resulted in the production of male, SCNT blastocysts, eliminating the possibility of a parthenogenetic origin. Of the four fibroblast cell lines tested as nuclear donor cells, two supported the routine production of blastocysts following SCNT.

CONCLUSIONS

The application of a modified SCNT technique (OSM) followed by embryo culture in hamster embryo culture medium-10 (HECM-10) allows, for the first time, the routine production of SCNT blastocysts, most of which appear normal by immunochemical, cytochemical and in vitro developmental criteria. These embryos will provide a resource for isolating ES cells and for studies of nuclear reprogramming by monkey cytoplasts.

Development of a monkey model for the study of primate genomic imprinting

An understanding of the role of imprinted genes in primate development requires the identification of suitable genetic markers that allow analysis of allele-specific expression and methylation status. Four genes, NDN (Necdin), H19, SNRPN and IGF2, known to be imprinted in mice and humans, were selected for study in rhesus monkeys along with two imprinting centres (ICs) associated with the regulation of H19/IGF2, NDN and SNRPN. GAPD was employed as a non-imprinted control gene. Primers designed to amplify polymorphic regions in these genes and ICs were based on human sequences. Genomic DNA was isolated from peripheral blood leukocytes of 93 rhesus macaques of Indian or Chinese-origin. Sequence analysis of amplicons resulted in the identification of 32 unique SNPs. Country-of-origin related differences in SNP distributions were evident. Since disruptions in imprinted gene expression and associated developmental abnormalities may result from in vitro embryo manipulation, we also examined imprinting in NDN, H19, SNRPN and IGF2 in rhesus monkey infants produced by natural mating or by ICSI. Muscle biopsies followed by RT-PCR and sequence analysis were performed in four heterozygous animals produced by natural mating and all four genes were expressed monoallelically supporting the conclusion that these genes are normally imprinted in monkeys. In the case of ICSI, five informative infants were selected based on parental analysis. Allele-specific studies indicated that the expected uniparental expression patterns were retained in animals produced from manipulated embryos. Moreover, methylation analysis revealed that CpG islands within H19/IGF2 and SNURF/SNRPN ICs were differentially methylated. The approach described here will allow examination of imprinting in the embryos and embryonic stem cells of the monkey.

Use of assisted reproductive technologies in the propagation of rhesus macaque offspring

The assisted reproductive technologies (ARTs) as tailored to the production of rhesus monkeys at the Oregon National Primate Research Center (ONPRC) are described. Efficient fertilization of mature oocytes recovered by aspiration from females subjected to follicular stimulation was achieved with fresh or frozen sperm by intracytoplasmic sperm injection (ICSI). Embryo development to the early cleavage stage occurred at high frequency. Cryopreserved embryos showed high postthaw survival and were also transferred in efforts to establish pregnancies. Three methods of transfer were evaluated, two involving embryo placement into the oviduct, laparoscopy and minilaparotomy, and a nonsurgical, transcervical approach that resulted in uterine deposition. Early cleaving embryos (Days 1-4) were transferred into the oviducts of synchronized recipients with optimal results and pregnancy rates of up to 36%. Pregnancy rates were similar when two fresh or frozen embryos were transferred (28- 30%), although more than two embryos had to be thawed to compensate for embryo loss during freeze-thawing. Normal gestational lengths, birth weights, and growth curves were seen with ART-produced infants compared with infants produced by natural mating in the timed mated breeding (TMB) colony at the ONPRC. In 72 singleton pregnancies established following the transfer of ART-produced embryos, the live-birth rate, at 87.5%, was statistically identical to that for the TMB colony. Further development of the ARTs should result in increasing use of these techniques to augment conventional approaches to propagating monkeys, especially those of defined genotypes.

Live birth after ovarian tissue transplant

Radiation and high-dose chemotherapy may render women with cancer prematurely sterile, a side-effect that would be avoided if ovarian tissue that had been removed before treatment could be made to function afterwards. Live offspring have been produced from transplanted ovarian tissue in mice and sheep but not in monkeys or humans, although sex steroid hormones are still secreted. Here we describe the successful transplantation of fresh ovarian tissue to a different site in a monkey, which has led to the birth of a healthy female after oocyte production, fertilization and transfer to a surrogate mother. The ectopically grafted tissue functions without surgical connection to major blood vessels and sets the stage for the transplantation of cryopreserved ovarian tissue in humans.

Nuclear transfer technology in mammalian cloning

The past several years have witnessed remarkable progress in mammalian cloning using nuclear transfer (NT). Until 1997 and the announcement of the successful cloning of sheep from adult mammary gland or fetal fibroblast cells, our working assumption was that cloning by NT could only be accomplished with relatively undifferentiated embryonic cells. Indeed, live offspring were first produced by NT over 15 years ago from totipotent, embryonic blastomeres derived from early cleavage-stage embryos. However, once begun, the progression to somatic cell cloning or NT employing differentiated cells as the source of donor nuclei was meteoric, initially involving differentiated embryonic cell cultures in sheep in 1996 and quickly thereafter, fetal or adult somatic cells in sheep, cow, mouse, goat, and pig. Several recent reviews provide a background for and discussion of these successes. Here we will focus on the potential uses of reproductive cloning along with recent activities in the field and a discussion concerning current interests in human reproductive and therapeutic cloning.

Nuclear transfer and cloning

The use of nuclear transfer in human reproductive and therapeutic cloning is reviewed with attention on the origins of this technology from its evolution to the present. The successes and limitations of mammalian reproductive cloning are itemized. A case is made against the use of human reproductive cloning to reproduce an existing person, based on the unacceptable risks to the embryo, fetus, or newborn. However, support is extended for human therapeutic cloning involving the derivation and use of embryonic stem cells to treat human disease.

Cryoloop vitrification yields superior survival of Rhesus monkey blastocysts

BACKGROUND

Vitrification using the cryoloop procedure was evaluated for preservation of non-human primate blastocysts by comparing survival results from two different cryoprotectant mixtures with prior results from controlled rate cooling.

METHODS

Rhesus monkey blastocysts were produced by intracytoplasmic sperm injection of mature oocytes from cycling females stimulated with recombinant human hormones. Morphologically well-formed blastocysts were divided between Procedure A (2.8 mol/l dimethylsulphoxide and 3.6 mol/l ethylene glycol with 0.65 mol/l sucrose and 25 micromol/l Ficoll in TALP-HEPES with 20% fetal bovine serum (TH20)) and Procedure B (3.4 mol/l glycerol and 4.5 mol/l ethylene glycol in TH20). After >48 h in liquid nitrogen, the removal of cryoprotectants was accomplished in the presence of a 3-step series of decreasing sucrose concentrations in TH20. Surviving embryos were co-cultured on buffalo rat liver cells.

RESULTS

Of 16 blastocysts vitrified via Procedure A, 38% survived with minimal lysis and only one hatched in culture; in contrast, of 33 blastocysts vitrified by Procedure B, 85% survived and 71% hatched. Of 22 blastocysts cryopreserved by conventional slow cooling, 36% survived and 6% hatched. Transfer into three recipients, each with two embryos vitrified with Procedure B, resulted in a successful twin-term pregnancy.

CONCLUSION

Modified cryoloop vitrification with a final solution of 3.4 mol/l glycerol and 4.5 mol/l ethylene glycol is a promising procedure for preserving Rhesus monkey blastocysts that is simple, rapid, and inexpensive.

Parthenogenetic activation of rhesus monkey oocytes and reconstructed embryos

This study determines the efficiency of sequential calcium treatments (electroporation or ionomycin) combined with protein synthesis (cycloheximide) or phosphorylation inhibitors (6-dimethylaminopurine) or the specific maturation promoting factor (MPF) inhibitor, roscovitine, in inducing artificial activation and development of rhesus macaque parthenotes or nuclear transfer embryos. Exposure of oocytes arrested at metaphase II (MII) to ionomycin followed by 6-dimethylaminopurine or to electroporation followed by cycloheximide and cytochalasin B induced pronuclear formation and development to the blastocyst stage at a rate similar to control embryos produced by intracytoplasmic sperm injection. Parthenotes did not complete meiosis or extrude a second polar body, consistent with their presumed diploid status. In contrast, oocytes treated sequentially with ionomycin and roscovitine extruded the second polar body and formed a pronucleus at a rate higher than that observed in controls. Following reconstruction by nuclear transfer, activation with ionomycin/6-dimethylaminopurine resulted in embryos that contained a single pronucleus and no polar bodies. All nuclear transfer embryos activated with ionomycin/roscovitine contained one large pronucleus. However, a third of these embryos emitted one or two polar bodies, clearly containing chromatin material. In summary, we have identified simple yet effective methods of oocyte or cytoplast activation in the monkey, ionomycin/6-dimethylaminopurine, electroporation/cycloheximide/cytochalasin B, and ionomycin/roscovitine, which are applicable to parthenote or nuclear transfer embryo production.

Intrauterine insemination-ready versus conventional semen cryopreservation for donor insemination: a comparison of retrospective results and a prospective, randomized trial

OBJECTIVE

To compare fecundity rates following intrauterine insemination (IUI) with donor sperm frozen conventionally versus an IUI-ready preparation.

DESIGN

Both retrospective results and a prospective, randomized study where recipients were assigned to one of two sperm cryopreservation methods in each cycle of intrauterine insemination are reported.

SETTING

University-based infertility practice, affiliated private practices, and andrology laboratory.

PATIENT(S)

Women desiring therapeutic insemination in an effort to establish pregnancy.

INTERVENTION(S)

Intrauterine insemination with donor sperm frozen conventionally or by an IUI-ready protocol.

MAIN OUTCOME MEASURE(S)

Cycle fecundity in donor IUI recipients.

RESULT(S)

In a retrospective analysis involving 642 inseminations in 209 recipients, 79 pregnancies were recorded for an overall pregnancy rate of 12.3% per insemination (or cycle): 11.3% with IUI-ready sperm and 13.9% with conventionally preserved sperm. In a follow-up prospective, randomized study, the pregnancy rate for IUI-ready sperm preparations was 36% per cycle (14 of 39) whereas that for conventionally preserved sperm was 19.6% per cycle (9 of 46). Thirteen of the 23 pregnancies occurred in the first study cycle of insemination; only two pregnancies were observed in patients undergoing more than four cycles of insemination.

CONCLUSION(S)

Cycle fecundity for IUI-ready donor sperm is equivalent to conventional cryopreserved sperm based on both prospective and retrospective assessments.

Human spermicidal activity of inorganic and organic oxidants

OBJECTIVE

To identify prospective oxidants that rapidly immobilize human sperm upon contact with human semen.

DESIGN

Inorganic, organic, and enzymatically-generated oxidants were mixed with human semen and spermicidal activity was tracked by a modified Sander-Cramer assay.

SETTING

Commercial and university-based laboratories.

PATIENT(S)

Semen samples obtained through a university-based andrology laboratory.

INTERVENTION(S)

Not applicable.

MAIN OUTCOME MEASURE(S)

Quantitation of spermicidal activity of test oxidants.

RESULT(S)

Sperm lost motility within 20 seconds of exposure to enzymatically generated free iodine (I(2)). Toluidine blue, phenazine methosulfate, or methylene blue exhibited some, albeit much less, spermicidal activity. Oxidants formed by mixing ascorbic acid with Fe(III)-EDTA, xanthine with xanthine oxidase, or by exposing sperm to the nitric oxide generator, SIN-1 (3-morpholinosydnonimine hydrochloride), were far less potent spermicidal agents.

CONCLUSION(S)

Free I(2) formed in situ and presented to semen is an extremely potent spermicide. Additional studies on methods of generating de novo I(2) may be beneficial in developing a novel new class of nondetergent-based spermicides.

Developmental competence of oocytes after ICSI in the rhesus monkey

Oocyte quantity and quality are critical to assisted reproductive technology (ART), yet few assessments beyond counting metaphase II (MII) oocytes exist. In this study, 30 +/- 2 oocytes per cycle were recovered from rhesus monkeys subjected to follicular stimulation with human gonadotrophins, of which 15 +/- 1 were MII. Oocyte quality was investigated by monitoring the developmental potential of oocytes subjected to intracytoplasmic sperm injection (ICSI). Despite uniform fertilization rates (71 +/- 4%), progression of embryos to blastocysts varied when expressed as a monthly average, from 20 to 85%, with lows from February to April and again in October, which could be attributed to developmental failure of a significant number of oocyte cohorts (14 of 55). Blastocyst rates, after elimination of failed cohorts, were uniform over time (59 +/- 4%). Neither culture conditions, the number of follicular stimulations, nor the individual sperm or oocyte donor were associated specifically with developmental failure, suggesting that intrinsic differences between stimulation cycles account for the observed variation in developmental potential. The in-vivo developmental competence of ICSI-produced embryos grown to blastocysts in vitro was also assessed. Two ongoing pregnancies and the birth of a normal female, 'Blastulina', represent landmarks in efforts to expand the use of ART in the rhesus monkey.

Mammalian cloning: possibilities and threats

The cloning of mammals originated with the production of limited numbers of genetically identical offspring by blastomere separation or embryo splitting. In the past few years, remarkable progress has been reported in cloning by nuclear transfer (NT) with donor nuclei recovered from embryonic, fetal or adult cells. Factors that contribute to the successful reprogramming of the transferred nucleus and the normal term development of the newly reconstructed embryo include the cell cycle stage of both the donor nucleus and recipient cytoplast, the timing of fusion and cytoplast activation, and the source of donor nuclei. The possibility of producing live offspring by somatic cell NT carries potential applications in animal husbandry, biotechnology, transgenic and pharmaceutical production, biomedical research, and the preservation of endangered species. However, the low efficiencies of cloning by NT coupled with high embryonic, fetal and neonatal losses may restrict immediate commercial applications in agriculture. These limitations notwithstanding, the greatest benefits and practical implications of this new technology could be in transplantation medicine and therapeutic cloning.

Estimates of genetic variance in an F2 maize population

Maize (Zea mays L.) breeders have used several genetic-statistical models to study the inheritance of quantitative traits. These models provide information on the importance of additive, dominance, and epistatic genetic variance for a quantitative trait. Estimates of genetic variances are useful in understanding heterosis and determining the response to selection. The objectives of this study were to estimate additive and dominance genetic variances and the average level of dominance for an F2 population derived from the B73 x Mo17 hybrid and use weighted least squares to determine the importance of digenic epistatic variances relative to additive and dominance variances. Genetic variances were estimated using Design III and weighted least squares analyses. Both analyses determined that dominance variance was more important than additive variance for grain yield. For other traits, additive genetic variance was more important than dominance variance. The average level of dominance suggests either overdominant gene effects were present for grain yield or pseudo-overdominance because of linkage disequilibrium in the F2 population. Epistatic variances generally were not significantly different from zero and therefore were relatively less important than additive and dominance variances. For several traits estimates of additive by additive epistatic variance decreased estimates of additive genetic variance, but generally the decrease in additive genetic variance was not significant.

Development and integration of an extended embryo culture program

OBJECTIVE

To study and evaluate a sequential, extended embryo culture system.

DESIGN

Prospective study.

SETTING

University-affiliated IVF clinic.

PATIENT(S)

All couples who were treated between October 1997 and July 1998.

INTERVENTION(S)

A standard human tubal fluid plus 10% serum substitute supplement (SSS) culture medium was used. The embryos were transferred to extended culture medium (S2 or G2) on day 3.

MAIN OUTCOME MEASURE(S)

Blastocyst formation and implantation and pregnancy rates.

RESULT(S)

Forty percent of the 20 donated cryopreserved embryos progressed to the blastocyst stage by day 6. Clinically, 7 (5.6%) of the 125 cycles did not result in a transfer. Blastocyst formation rates ranged from 33%-63% in the five study groups. Implantation rates ranged from 15%-52% and pregnancy rates ranged from 37%-75%.

CONCLUSION(S)

Extended culture to day 5 or 6 results in acceptable blastocyst formation rates, implantation rates, and pregnancy rates.

Fecundability trends among sperm donors as a measure of donor performance

OBJECTIVE

To examine fecundability trends among sperm donors.

DESIGN

Retrospective analysis.

SETTING

University-based sperm bank and donor insemination program.

PATIENT(S)

Sperm donors and recipients.

INTERVENTION(S)

A group of recipients underwent IUI with cryopreserved donor sperm. Fecundability was calculated for 20 sperm donors over 800 insemination cycles.

MAIN OUTCOME MEASURE(S)

Average fecundability per donor was compared for the first 40 cycles of a donor's use and for those donors within a group of more fertile recipients. Sperm parameters, recipient ages, and number of unique recipients for each donor were analyzed.

RESULT(S)

Average donor fecundability is constant; however, individual donors demonstrated differences among their fecundabilities (overall mean, 0.09; range, 0.01-0.26). These differences persisted for donors among a group of more fertile recipients (overall mean, 0.12; range, 0.02-0.35). A donor's fecundability at 15 cycles is predictive of his future performance.

CONCLUSION(S)

Differences in fecundability exist among sperm donors which cannot be discerned through routine semen parameters. Sperm donor fecundability should be analyzed periodically, and directors of sperm banks should consider discontinuing use of a donor whose outcome is substandard.

Nuclear transfer in the rhesus monkey: practical and basic implications

In early 1997, the birth of a lamb after transfer of the nucleus from an adult mammary gland cell into an enucleated oocyte, along with the production of rhesus monkeys by nuclear transfer of embryonic cells, marked a reemergence of the field of mammalian cloning. Clonally derived rhesus monkeys would be invaluable in biomedical research, and the commercial interests in transgenic sheep and cattle propagated by cloning are substantial. Nuclear transfer technology is under consideration in human in vitro fertilization clinics to overcome infertility secondary to advanced maternal age or mitochondrial-based genetic disease. Nuclear transfer involves preparing a cytoplast as a recipient cell, in most cases a mature metaphase II oocyte from which the chromosomes have been removed. A donor nucleus cell is then placed between the zona and the cytoplast, and fusion, as well as cytoplast activation, is initiated by electrical stimulation. Successful reprogramming of the donor cell nucleus by the cytoplast is critical--a step that may be influenced by cell cycle stage. Embryos produced by nuclear transfer are cultured in vitro for several cell divisions before cryopreservation or transfer to the oviduct or uterus of a host mother. The efficiency of producing live young by nuclear transfer in domestic species is low, with a high frequency of developmental abnormalities in both preterm and term animals. However, a number of pregnancies have now been established using fetal cells as the source of donor nuclei. The use of cell lines not only allows large clone sizes but also supports the ability to genetically manipulate cells in vitro before nuclear transfer. Ongoing research focused on the production of clonally derived rhesus monkeys using fetal fibroblasts and embryonic stem cells as the source of donor nuclei will be reviewed.

Motility potential of macaque epididymal sperm: the role of protein phosphatase and glycogen synthase kinase-3 activities

Human and monkey ejaculated sperm contain protein phosphatase-1 (PP1), PP1 inhibitor 2 (12), and glycogen synthase kinase-3 (GSK-3). Inhibition of ejaculated human sperm protein phosphatase (PP) activity with calyculin-a (CL-A) significantly stimulates motility, implicating protein dephosphorylation in motility regulation. The present experiments were conducted to characterize and compare PP and GSK-3 activity in monkey caput and caudal epididymal sperm, to determine the cellular distribution of these enzymes, and to test the thesis that epididymal sperm PP activity is inversely related to motility. Caput epididymal sperm populations, (8.8% motile) contained levels of PP activity that were >3 times as high as those of caudal spermatozoa. This PP activity was further identified by inhibitor response profiles as PP1. In both caput and caudal sperm, the majority of this PP1 activity was localized in 100,000 x g soluble fractions. Western blot analysis indicated that a portion of this difference was the result of elevated amounts of PP1 in caput compared with caudal epididymal sperm. The presence of GSK-3 activity was undetectable in 100,000 x g insoluble fractions of epididymal sperm, whereas both caput and caudal sperm soluble fractions contained GSK-3 activity, which was approximately threefold higher in caput sperm compared with caudal populations. Treatment of caput epididymal sperm from the rhesus macaque with the PP inhibitor CL-A resulted in a significant, dose-dependent increase from 8 to 38% motile cells (without any effect on their path velocity). In contrast, CL-A had no significant influence on either percent motility or path velocity of caudal epididymal sperm. Cytosolic PP1 and GSK-3 activities appear to be inversely related to the motility of monkey epididymal sperm and may have a regulatory role in the development of the potential for motility in epididymal sperm.

Characterization of protein phosphatases in mouse oocytes

Okadaic acid (OA) enhances the resumption of meiosis in mouse oocytes, indicating that serine/threonine protein phosphatase-1 (PP1) and/or PP2A is involved. However, specific identification of PP1 and/or PP2A in mouse oocytes has not been reported. Here we demonstrate that fully grown germinal vesicle-intact (GVI) mouse oocytes contain mRNA corresponding to two isotypes of PP1, PP1alpha and PP1gamma. In addition, the transcript for PP2A was also present. At the protein level only PP1alpha and PP2A were recognized in fully grown GVI oocytes by Western blot analysis. Neither of the PP1gamma spliced variant proteins, PP1gamma1 and PP1gamma2, was detectable. Immunohistochemical analysis of ovarian tissue from gonadotropin-stimulated adult mice resulted in subcellular localization of both PP1alpha and PP2A, but not PP1gamma, in oocytes from all stages of folliculogenesis. In primordial oocytes, PP1alpha and PP2A were present in the cytoplasm. In more advanced stages of oogenesis, PP1alpha, although still present in the cytoplasm, was highly concentrated in the nucleus, whereas PP2A was predominantly cytoplasmic with a distinct reduction in the nuclear area. Both PP1alpha and PP2A were immunodetectable in oocytes during the prepubertal period. Eleven-day-old mouse oocytes, considered OA-insensitive and germinal vesicle breakdown (GVB)-incompetent, displayed both PP1alpha and PP2A predominantly in the cytoplasm. By 15 days of age mouse oocytes, which are beginning to acquire OA sensitivity and GVB competence, showed a relocation of PP1alpha into the nucleoplasm while PP2A remained predominantly cytoplasmic. This is the first specific identification of PP1alpha and PP2A in mouse oocytes. The differential localization of PP1alpha and PP2A, in addition to the relocation of PP1alpha during the acquisition of meiotic competence, suggests that these PPs have distinct regulatory roles during the resumption of meiosis.

Oocytes are a source of catecholamines in the primate ovary: evidence for a cell-cell regulatory loop

Catecholamines, thought to derive from the extrinsic innervation of the ovary, participate in the regulation of ovarian development and mature gonadal function. Recently, intraovarian neurons containing tyrosine hydroxylase (TH), the rate-limiting enzyme in catecholamine biosynthesis, were described in the ovary of nonhuman primates. We now show that the primate ovary expresses both the genes encoding TH and dopamine beta-hydroxylase (DBH), the key enzymes in norepinephrine (NE) biosynthesis. Ovarian neurons were identified as a site of TH and DBH gene expression, and surprisingly, oocytes were identified as an exclusive site of DBH synthesis. Oocytes contain neither TH mRNA nor protein, indicating that they are unable to synthesize dopamine (DA). They did, however, express a DA transporter gene identical to that found in human brain. The physiological relevance of this transporter system and DBH in oocytes was indicated by the ability of isolated oocytes to metabolize exogenous DA into NE. Isolated follicles containing oocytes-but not those from which the oocytes had been removed-responded to DA with an elevation in cAMP levels; this elevation was prevented by propranolol, a beta-adrenoreceptor antagonist. The results suggest that oocytes and somatic cells are linked by a neuroendocrine loop consisting of NE synthesized in oocytes from actively transported DA and cAMP produced by somatic follicular cells in response to NE-induced beta-adrenoreceptor activation.

Uneven distribution of desmosterol and docosahexaenoic acid in the heads and tails of monkey sperm

Previously we demonstrated high concentrations of desmosterol and docosahexaenoic acid (DHA, 22:6 n-3) in monkey testes and sperm. Desmosterol, a cholesterol precursor, is not present elsewhere in the body. High concentrations of DHA are found elsewhere only in the retina and brain. To examine the distribution of these compounds in the heads and tails of sperm, we separated them and determined their sterol, fatty acid, and phospholipid molecular species composition. Desmosterol predominated in tails (134.4 vs. 1.7 microg/10(9) cells in heads). The cholesterol content was also greater in the tails (66.2 vs. 30.3 microg/10(9) cells in heads). Sperm tails had more polyunsaturated fatty acids than the heads (34.1 vs. 12.1% of total fatty acids) which resulted mainly from the higher contents of DHA (19.6 vs. 1.1%) and arachidonic acid (20:4 n-6) (6.4 vs. 1.6%) in the tails. These differences in fatty acid composition occurred mainly in phospholipids: phosphatidyl choline and phosphatidyl ethanolamine for n-3 fatty acids and phosphatidyl serine and cardiolipin for n-6 fatty acids. Fifteen phospholipid molecular species were identified. Sperm tails had more molecular species containing unsaturated fatty acids than the heads. Our results reveal the large differences in membrane lipid composition between the heads and tails of sperm. Most (99%) of the desmosterol and DHA in sperm is located in the tail. These differences may be responsible for the different functions of these two components of sperm. The large number of double bonds in DHA, six, and in desmosterol, two, may contribute to the membrane fluidity necessary for the motility of the sperm tails.

Recent progress in mammalian cloning

PURPOSE

Our purpose was to review recent progress in the use of nuclear transfer technology to produce genetically identical mammals.

METHODS

A literature review was conducted.

RESULTS

The reasons for cloning nonhuman mammals are manyfold including commercial, biomedical, and basic research applications. Individual steps in the nuclear transfer process are itemized, along with a detailed description of the specific approaches used in the production of Dolly, NETI, and DITTO. The potential application of nuclear transfer in the treatment of human infertility is also considered, along with bioethical concerns. Finally, insights are provided concerning the future application of cloning technology in rhesus macaques.

CONCLUSIONS

The cloning of a lamb (Dolly) from an adult, mammary gland cell coupled with the successful production of rhesus monkeys (NETI and DITTO) by nuclear transfer of embryonic cells marks the beginning of a "Golden Age" in the development and application of somatic cell cloning technology in mammals.

Transient exposure of rhesus macaque oocytes to calyculin-A and okadaic acid stimulates germinal vesicle breakdown permitting subsequent development and fertilization

Exposure of mammalian oocytes to the protein phosphatase (PP)-1 (PP1) and PP2A inhibitor okadaic acid (OA) stimulates oocyte meiosis. However, treated oocytes do not develop beyond metaphase I (MI), and they display morphological aberrations. Experiments were conducted to define inhibitor treatment conditions for macaque oocytes that would result in germinal vesicle breakdown (GVB) stimulation and completion of meiosis without significant cytoplasmic abnormalities. As described above for OA, continual exposure of macaque oocytes to 50 nM calyculin-a (CL-A) significantly enhanced GVB at 24 h compared to that in controls, and the majority of the treated oocytes displayed cytoplasmic abnormalities. However, transient exposure (10 min) of rhesus macaque oocytes to either 50 nM CL-A or 1.0 microM OA enhanced GVB rates compared to that in controls and did not increase the incidence of cytoplasmic abnormalities. Meiotic maturation from germinal vesicle-intact oocytes to MII was enhanced following transient treatment with CL-A or OA compared to that in controls; however, development from MI to MII occurred at a similar frequency. In vitro-matured oocytes transiently exposed to OA and CL-A were capable of fertilization. In addition, ovarian immunohistochemical analysis revealed that both PP1 and PP2A were present in macaque oocytes. PP1 was localized throughout the cytoplasm with a predominance in the nucleus, whereas PP2A was evenly distributed throughout the cytoplasm with a reduction in the nuclear area. These results taken together-differential developmental responses to inhibitor treatment and intracellular enzyme localizations-may be indicative of multiple regulatory roles of PP1 and/or PP2A during meiosis.

A bolus of recombinant human follicle stimulating hormone at midcycle induces periovulatory events following multiple follicular development in macaques

The efficacy of follicle stimulating hormone (FSH) as an alternative to luteinizing hormone (LH)/human chorionic gonadotrophin (HCG) for the initiation of periovulatory events in primate follicles is unknown. A single bolus of 2500 IU recombinant (r)-hFSH was compared to 1000 IU r-HCG for its ability to promote oocyte nuclear maturation and fertilization, granulosa cell luteinization and corpus luteum function following r-hFSH (60 IU/day) induction of multiple follicular development in rhesus monkeys. Following the r-hFSH bolus, bioactive luteinizing hormone concentrations were <3 ng/ml. Peak concentrations of serum FSH (1455+/-314 mIU/ml; mean+/-SEM) were attained 2-8 h after r-hFSH, and declined by 96 h. Bioactive HCG concentrations peaked between 2-8 h after r-HCG and remained > or = 100 ng/ml for >48 h, while immunoreactive FSH concentrations were at baseline. The proportion of oocytes resuming meiosis and undergoing in-vitro fertilization (IVF) were comparable for r-hFSH (89%; 47+/-19%) and r-HCG (88%; 50+/-17%). In-vitro progesterone production and expression of progesterone receptors in granulosa cells did not differ between groups. Peak concentrations of serum progesterone in the luteal phase were similar, but were lower 6-9 days post-FSH relative to HCG. Thus, a bolus of r-hFSH was equivalent to r-HCG for the reinitiation of oocyte meiosis, fertilization and granulosa cell luteinization, but a midcycle FSH surge did not sustain normal luteal function in primates.

Sperm abnormalities in retinitis pigmentosa

PURPOSE

To determine the fatty acid composition of erythrocytes and sperm, along with the functional characteristics of sperm, in patients with retinitis pigmentosa. Sperm and retinal cells share important homologies. Both are rich in the highly polyunsaturated fatty acid, docosahexaenoic acid (DHA, 22:6[n-3]), and both contain a structural component called the axoneme. Low concentrations of DHA in the retina of monkeys are known to cause visual impairment. Because blood levels of DHA in retinitis pigmentosa patients are less than normal, reduced DHA in the retina might contribute to the visual impairment characteristic of this disease. This study was conducted on the hypothesis that the sperm of retinitis pigmentosa patients might be abnormal and that these abnormalities might infer similar lipid and structural abnormalities of the retina.

METHODS

The lipid composition of erythrocytes and sperm (fatty acids and sterols) and sperm function were analyzed in 26 patients with retinitis pigmentosa and in 8 healthy men.

RESULTS

The sperm of patients with retinitis pigmentosa had a much lower DHA concentration, a lower desmosterol-to-cholesterol ratio, reduced motility, abnormal structure, and lower sperm counts compared with that in normal subjects. Usher's II patients exhibited the most pronounced reductions of DHA in sperm. Sperm DHA concentration was positively correlated to sperm motility, to sperm count, and to the desmosterol-to-cholesterol ratio. Lower erythrocyte DHA was also observed in retinitis pigmentosa patients.

CONCLUSIONS

These results indicate that the sperm of patients with retinitis pigmentosa, particularly those with Usher's II, have an abnormal lipid composition that is associated with reduced motility. The possibility exists that these patients might have similar abnormalities in the DHA biochemistry of the retina. Sperm biochemistry and function may be a marker for this disease. A clinical trial of DHA in retinitis pigmentosa is suggested for future study.

Initiation of periovulatory events in gonadotrophin-stimulated macaques with varying doses of recombinant human chorionic gonadotrophin

During in-vitro fertilization (IVF) cycles, a large bolus of human chorionic gonadotrophin (HCG) is used to induce periovulatory events, but the efficacy of lower doses is undefined. Following follicular stimulation in rhesus monkeys, oocyte nuclear maturation, IVF, granulosa cell luteinization and corpus luteum function were compared after injection of 100, 300 or 1000 IU recombinant HCG or 1000 IU urinary HCG. Bioactive HCG rose to peak concentrations within 2 h that were proportional to the dose administered (100 < 300 < 1000 IU, recombinant HCG = urinary HCG). The duration of surge values (>100 ng/ml) was also dose-dependent (0 h, 100 IU; 24 h, 300 IU; >48 h, 1000 IU, recombinant and urinary HCG). While the proportions of oocytes resuming meiosis and undergoing IVF were similar among groups, fewer animals yielded fertilizable oocytes following 100 and 300 IU (five of nine) compared to 1000 IU recombinant and urinary HCG (nine of 10). Peak values of serum progesterone in the luteal phase were similar, but declined 2 days earlier after 100 and 300 IU relative to 1000 IU recombinant and urinary HCG. Thus, 3-10 fold lower doses of HCG elicit low amplitude surges of short duration that induce periovulatory events such as re-initiation of oocyte meiosis and granulosa cell luteinization. However, oocyte fertilization and luteal function may optimally require surges of higher amplitude and longer duration similar to those produced by standard doses of 1000 IU recombinant or urinary HCG.

Rhesus monkeys produced by nuclear transfer

Genetically identical nonhuman primates can provide a powerful animal model for gene therapy and research activities where the physiological parameters directly or indirectly under study are heritable. Here we demonstrate that nuclear transfer is a viable technology for the production of identical rhesus macaques. Oocytes recovered from gonadotropin-treated females were enucleated by aspiration of the first polar body and underlying ooplasm, then activated by cycloheximide exposure. Individual diploid blastomeres, recovered from in vitro-fertilization-produced embryos (either fresh or frozen-thawed) and used as nuclear donors, were injected under the zona pellucida of enucleated (chromosome-free) oocytes and fused by electric pulses. The reconstituted embryos were cocultured on buffalo rat liver cells before cryostorage and transfer to synchronized host mothers. Of the 9 females receiving a total of 29 reconstituted embryos, 3 became pregnant, with two live births resulting, one male and one female. The parentage of both infants was established unequivocally by genotype analysis at 7 highly variable short tandem repeat loci.

An intrauterine insemination-ready cryopreservation method compared with sperm recovery after conventional freezing and post-thaw processing

OBJECTIVE

To test a sucrose-glycerol cryoprotectant for IUI-ready sperm preparation.

DESIGN

Semen aliquots from normozoospermic donors either were subjected to conventional semen freezing (TES and Tris yolk buffer in 7.4% final glycerol) with post-thaw processing or were preprocessed and frozen in HEPES-buffered human tubal fluid with 1% human serum albumin, 4% sucrose, and 6% glycerol. All aliquots were cooled to 4 degrees C, exposed to liquid nitrogen vapors, and stored in liquid nitrogen. Aliquots from each were processed by centrifugation resuspension or by centrifugation in Percoll (Pharmacia, Alameda, CA) before sperm parameters were analyzed.

SETTING

University-based andrology laboratory.

MAIN OUTCOME MEASURE(S)

Recovery of motile sperm.

RESULT(S)

Percoll processing produced preparations with higher percentages of motile cells; however, cryopreserved sperm had a lower recovery of motile sperm compared with Percoll-processed fresh semen or centrifugation/resuspension-processed fresh or frozen samples. The percentages of sperm with normal morphologies were significantly increased in the IUI-ready samples compared with samples frozen conventionally. The IUI-ready Percoll-processed sample produced the best results, with a final mean motility of 36% and an overall yield of motile sperm of 17.4%.

CONCLUSION(S)

The sucrose-glycerol-based cryoprotectant produced an IUI-ready preparation with motile sperm recovery comparable to that of conventional semen cryopreservation but with improved percent morphology.

Sperm-induced oocyte activation in the rhesus monkey: nuclear and cytoplasmic changes following intracytoplasmic sperm injection

Intracytoplasmic sperm injection (ICSI) has increased the potential of the assisted reproductive technologies to propagate mammalian species and has provided an opportunity for research into cell cycle control and the mechanisms involved in sperm-induced oocyte activation. We have investigated the efficacy of ICSI in the rhesus monkey, the mechanism of fertilization following sperm injection and the cytoskeletal rearrangement that occurs upon oocyte activation. These studies were conducted on mature, and to a lesser extent, immature oocytes. Ejaculated spermatozoa, washed, capacitated and activated before immobilization, were injected into oocytes using conventional ICSI methodology. Sperm injection into mature oocytes induced oocyte activation (19/22; 86%) and pronuclear formation. In contrast, sham-injected oocytes did not activate readily (2/16; 13%). To localize oocyte activation factor(s), spermatozoa were separated mechanically into heads and tails which were then injected individually into mature oocytes. Activation occurred in 87% (20/23) of oocytes receiving heads. After tail injection, a single microtubule aster was nucleated and one pronucleus (PN) was seen in four of 21 oocytes. Intracytoplasmic injection of sperm extract (SE) resulted in oocyte activation at a significantly higher rate than occurred following sham injection (76 versus 13%). Sperm-induced oocyte activation was also evaluated in immature metaphase (MI) oocytes; activation occurred in 46% (12/26) of cases; however, only 8% of the activated oocytes exhibited 2 PN. Finally, beta-tubulin localization in untreated and taxol-treated oocytes was established as a marker for cytoplasmic changes associated with oocyte activation. These results are consistent with the hypothesis that spermatozoa contain an oocyte activating factor(s) which is primarily localized in the sperm head. Moreover, an activation response is limited to mature oocytes and is accompanied by cytoskeletal changes analogous to those seen following conventional fertilization.

Enhancement of primate oocyte maturation and fertilization in vitro by inhibin A and activin A

OBJECTIVE

A role for inhibin and activin in primate oocyte maturation was investigated.

DESIGN

The maturation and fertilization of rhesus monkey oocytes recovered from the excised ovaries of nine regularly cycling animals was compared for untreated germinal vesicle (GV)-intact controls versus oocytes cultured in the presence of inhibin, activin, inhibin + activin, or in a combination with follistatin.

SETTING

Nonhuman primates in a research institute environment.

INTERVENTIONS

Bilateral oophorectomy.

MAIN OUTCOME MEASURE

Oocyte maturation from germinal vesicle breakdown (GVBD) to metaphase II (MII) and fertilization.

RESULTS

Germinal vesicle breakdown, progression to MII and fertilization was monitored in oocytes cultured for 48 hours. Activin alone, at an optimum concentration of 100 ng/mL, stimulated GVBD whereas both GVBD and MII development was enhanced in the presence of inhibin + activin. The latter also accelerated the rate of maturation to MII. All treatment groups exhibited a higher incidence of GVBD compared with controls. When follistatin was added, the stimulatory effect of activin or activin + inhibin was abolished. Exposure to medium containing inhibin + activin significantly increased the percentage of MII oocytes that fertilized compared with controls (68% versus 25%, respectively).

CONCLUSIONS

Inhibin and activin are potent stimulators of primate oocyte maturation, producing mature oocytes in vitro that fertilize with high efficiency.

Differential preimplantation development of rhesus monkey embryos in serum-supplemented media

Several media, some augmented with amino acids, have been formulated recently, based on simplex optimization, to support the preimplantation development of mouse embryos. For the highly limited studies on preimplantation development of nonhuman primate embryos, a complex medium (CMRL-1066) has been employed. Our objective was to compare the developmental ability of rhesus monkey embryos in a simple medium containing amino acids, KSOM/AA, with the complex media used previously. Zygotes (99) were recovered following in vitro fertilization (IVF) from six monkeys, allocated to either CMRL or KSOM/AA both containing 10% fetal calf serum (FCS), and monitored daily until reaching the expanded or hatched blastocyst stage. The distribution of cells between the inner cell mass (ICM) and trophectoderm was determined at the end of culture by differential nuclear staining. Although a greater number of embryos cultured in KSOM/AA vs. CMRL developed to the morula stage (80%) and beyond (66% to expanded blastocyst), the differences were not significant. Such embryos in KSOM/AA did, however, develop at a significantly faster rate, on average, reaching the expanded blastocyst stage 26 hr earlier than did embryos cultured in CMRL. KSOM/AA embryos hatched in less time and had a higher percentage (43 vs. 34) of cells allocated to the ICM. These results indicate that a simple medium, KSOM/AA, in the presence of serum, supports the development of rhesus monkey embryos at high efficiency and at a faster rate than that observed for embryos cultured in the complex medium, CMRL-1066.

Midcycle administration of a progesterone synthesis inhibitor prevents ovulation in primates

Progesterone receptors appear in granuloma cells of preovulatory follicles after the midcycle gonadotropin surge, suggesting important local actions of progesterone during ovulation in primates. Steroid reduction and replacement during the gonadotropin surge in macaques was used to evaluate the role of progesterone in the ovulatory process. Animals received gonadotropins to induce development of multiple preovulatory follicles, followed by human chorionic gonadotropin (hCG) administration (day 0) to promote oocyte (nuclear) maturation, ovulation, and follicular luteinization. On days 0-2, animals received no further treatment; a steroid synthesis inhibitor, trilostane (TRL); TRL + R5020; or TRL + dihydrotestosterone propionate (DHT). On day 3, ovulation was confirmed by counting ovulation sites and collecting oviductal oocytes. The meiotic status of oviductal and remaining follicular oocytes was evaluated. Peak serum estradiol levels, the total number of large follicles, and baseline serum progesterone levels at the time of hCG administration were similar in all animals. Ovulation sites and oviductal oocytes were routinely observed in controls. Ovulation was abolished in TRL. Progestin, but not androgen, replacement restored ovulation. Relative to controls, progesterone production was impaired for the first 6 days post-hCG in TRL, TRL + R5020, and TRL + DHT. Thereafter, progesterone remained low in TRL but recovered to control levels with progestin and androgen replacement. Similar percentages of mature (metaphase II) oocytes were collected among groups. Thus, steroid reduction during the gonadotropin surge inhibited ovulation and luteinization, but not reinitiation of oocyte meiotic maturation, in the primate follicle. The data are consistent with a local receptor-mediated role for progesterone in the ovulatory process.

Developmental potential of embryos produced by in-vitro fertilization from gonadotrophin-releasing hormone antagonist-treated macaques stimulated with recombinant human follicle stimulating hormone alone or in combination with luteinizing hormone

We previously demonstrated, in luteinizing hormone (LH)-deficient macaques, that follicular growth and maturation occurred with administration of exogenous (recombinant human) follicle stimulating hormone (r-hFSH) alone, and that the oocytes recovered fertilized at a notably higher rate than their counterparts from animals receiving both r-hFSH and r-hLH (Zelinski-Wooten et al., 1995). Here, the developmental potential of embryos produced from animals treated with r-hFSH alone or in combination with r-hLH was evaluated. Embryos (n = 127) were cryopreserved, thawed and either co-cultured on buffalo rat liver cells until the hatched blastocyst stage or transferred to synchronized recipients. Although embryos from each treatment group demonstrated a similar ability to develop to hatched blastocysts with a definitive inner cell mass, a significant difference was seen in cryosurvival (56 versus 78%) and in developmental rate to the hatched blastocyst (12 versus 10 days) between embryos from the r-hFSH alone and the combination group respectively. Pregnancies resulted following oviductal embryo transfers in both groups, with corpus luteum rescue occurring on days 12-16 of the luteal phase. In summary, r-hFSH alone during the pre-ovulatory interval is adequate for the gametogenic events required to produce embryos that develop either in vitro or in vivo; however, exposure to r-hLH may improve embryo viability and the rate of development.

Primate sperm contain protein phosphatase 1, a biochemical mediator of motility

Sperm motility initiation, capacitation, and hyperactivation are modulated by an interplay of intracellular Ca2+, cAMP, and pH. Mechanisms by which these mediators alter sperm function have not been elucidated but may involve reversible alterations in regulatory protein phosphorylation. Studies were designed 1) to investigate the influence of the protein phosphatase (PP) inhibitor calyculin A (CA) on human sperm motility and 2) to characterize the CA-sensitive PP and its endogenous regulators in human and rhesus monkey sperm. CA (50 nM) treatment of human sperm resulted in an increase in percentage motility and an acceleration in mean path velocity. Inhibition of either protein phosphatase-1 (PP1) or protein phosphatase-2A (PP2A) could be responsible for this motility stimulation, since both of these phosphatases are sensitive to nanomolar quantities of CA. PP activity in human (n = 4) and rhesus monkey (n = 4) sperm sonicates was measured using [32P]-phosphorylase-a, the preferred substrate for PP1 and PP2A, in the absence of divalent cations. Human (6.2 +/- 4.5 x 10(-2) mU/10(6) sperm) and monkey (4.3 +/- 0.8 x 10(-2) mU/10(6) sperm) sonicates contained activity tentatively identified as PP1 on the basis of inhibition profiles in okadaic acid (OA) and CA. Western blot analysis with antibodies against various isoforms of PP1 subsequently documented the presence of PP1 gamma 2 in human and monkey sperm. PP1 activity in most tissues is regulated by the heat-stable inhibitors I1 or I2. Sperm sonicates contained inhibitor activity similar to I2 as well as glycogen synthase kinase-3 (GSK-3) activity, which is involved in the activation of the PP1-I2 complex. These results indicate, for the first time, that human and rhesus monkey sperm contain PP1 and regulators of PP1 and that inhibition of PP1 activity by CA can enhance motility.

Maturity and fertility of rhesus monkey oocytes collected at different intervals after an ovulatory stimulus (human chorionic gonadotropin) in in vitro fertilization cycles

In rhesus monkeys undergoing ovarian stimulation for in vitro fertilization (IVF), a midcycle injection of human chorionic gonadotropin (hCG) substitutes for the LH surge and induces preovulatory oocyte maturation. The time interval between injection and oocyte collection, ideally, allows for the completion of oocyte maturation without ovulation, which would reduce the number of oocytes available for harvest. To evaluate the influence of this time interval on oocyte parameters following hCG administration, we conducted a series of gonadotropin treatment protocols in 51 animals in which the interval from hCG administration to follicular aspiration was systematically varied from 27 to 36 hr. Follicle number and size, evaluated prior to hCG administration by sonography, did not vary significantly or consistently with preovulatory maturation time. Oocytes were harvested by laparotomy or laparoscopy, and scored for maturity before insemination. The percentage of mature, metaphase II (MII) oocytes at recovery increased significantly with increasing preovulatory time and was inversely proportional to that of metaphase I (MI) oocytes. However, oocyte yield tended toward a progressive decrease with increasing preovulatory maturation times from a high of 27 oocytes at 27 hr to a low of 17 oocytes/animal at the 36 hr time interval. Fertilization levels declined significantly from a high of 50% at 27 hr to a low of 30% at 36 hr. Thus, although higher percentages of mature oocytes were recovered at the longer time intervals, optimal oocytes/embryo harvests were realized after the shorter time intervals (27 and 32 hr) and are most compatible with the goal of achieving high yields of fertile oocytes and embryos following gonadotropin stimulation in rhesus monkeys.

Regulation of human sperm motility and hyperactivation components by calcium, calmodulin, and protein phosphatases

The role of Ca2+, calmodulin, and protein phosphatases on motility and hyperactivation of noncapacitated, capacitating, and detergent-permeabilized reactivated human sperm was examined. In noncapacitated sperm, W7 inhibited percent motility (%MOT), curvilinear velocity (VCL), amplitude of lateral head displacement (ALH), and percent hyperactivation (%HYP) in an extracellular Ca2+ concentration-dependent manner (p < .05). However, in capacitating sperm, inhibition of motility by W7 was independent of external Ca2+. Treatment of reactivated sperm with a synthetic calmodulin inhibitor peptide decreased VCL and ALH in a Ca(2+)-dependent manner (p < .05). Ca2+ exhibited a dramatic influence on motility within a narrow concentration range (0.7 to 1.0 microM) in reactivated sperm. A calmodulin-dependent protein phosphatase (PP2B) was identified by activity assay, immunoblotting, and dephosphorylation of endogenous phosphoproteins. The sperm enzyme, unlike bovine brain PP2B, was inhibited by 1 microM okadaic acid (OA) in the presence of Mn2+, suggesting that the sperm enzyme is unique. In reactivated sperm, inhibition of endogenous PP2B-like activity with anti-PP2B antibodies altered ALH, whereas OA altered both VCL and ALH and also inhibited a subset of Ca(2+)-dependent dephosphorylations of cAMP-dependent phosphoproteins in capacitating sperm. These results suggest (1) an important role for calmodulin and PP2B in Ca(2+)-regulated motility parameters, particularly ALH, and (2) that modulation of human sperm motility, including hyperactivation by cAMP-dependent phosphorylation, requires calmodulin-dependent as well as other protein dephosphorylations.

Follicle stimulating hormone alone supports follicle growth and oocyte development in gonadotrophin-releasing hormone antagonist-treated monkeys

Both follicle stimulating hormone (FSH) and luteinizing hormone (LH) are proposed requirements for follicular growth and steroidogenesis; however, the role of LH in primate folliculogenesis is unclear. Follicular stimulation by recombinant human FSH (n = 5) with and without recombinant LH (1:1; n = 6) following 90 days of gonadotrophin-releasing hormone (GnRH) antagonist (Antide) treatment in macaques was evaluated. Human chorionic gonadotrophin (HCG) was administered when six follicles > or = 4 mm were observed. Oocytes were aspirated 27 h later and inseminated in vitro. Chronic Antide reduced serum oestradiol and bioactive LH to concentrations observed in hypophysectomized rhesus monkeys. Multiple follicular growth required a longer interval following recombinant FSH (12 +/- 1 days) than recombinant FSH+recombinant LH (9 +/- 0.2 days), but the total number of follicles/animal did not differ between groups. The day prior to HCG, oestradiol concentrations were 4-fold less following recombinant FSH compared to recombinant FSH+recombinant LH. With recombinant FSH, more oocytes completed meiosis to metaphase II (51%) and fertilized (89 +/- 5%) relative to recombinant FSH+recombinant LH (12 and 52 +/- 11% respectively). Follicular growth and maturation in LH-deficient macaques occurred with FSH alone. Thus, LH is not required for folliculogenesis in primates. Higher fertilization rates following follicular stimulation with FSH alone suggest that the presence of LH with FSH (1:1) during the pre-ovulatory interval impairs gametogenic events in the periovulatory period.

Functional characterization of the primate sperm acrosomal antigen (PSA-63)

Monoclonal antibody (HS-63) raised in mice against human ejaculated sperm, polyclonal antibodies raised in rabbits against the cognate mouse testicular antigen (MSA-63; or Fab) and polyclonal antibodies raised in the rabbit against recombinant fusion proteins (GST-63) showed acrosomal localization in permeabilized rhesus monkey and human ejaculated sperm. Tail localization of the cognate primate sperm antigen (PSA-63) was also seen with intact MSA-63 antibodies and Fab fragments. The ability of these antibodies to inhibit sperm binding to the zona pellucida was measured with hemizona binding assays (HZAs). HS-63 (1.2 mg/ml) inhibited rhesus monkey sperm binding (mean +/- SEM) to homologous hemizonae (treatment, 15.5 +/- 3.3; control, 58.9 +/- 9.4; P < 0.025), whereas comparable concentrations of protein from nonimmunized mouse preparations were inactive (ascites fluid, 67.6 +/- 43.5; no ascites fluid, 72.0 +/- 44.6). Intact MSA-63 antibodies inhibited (up to 99%) monkey sperm-zona binding in a concentration-dependent manner. Moreover, inhibition in this case by intact MSA-63 antibody was limited to capacitated sperm. Similarly, intact MSA-63 antibodies inhibited (up to 85%) human sperm binding to homologous zonae in an antibody concentration-dependent manner. Fab fragments derived from MSA-63, when present in insemination mixtures (0.5 mg/ml), inhibited (P < 0.01) primate sperm binding to homologous hemizonae (monkey, 9.6 +/- 3; human sperm 9.4 +/- 2) compared with matched hemizona controls (monkey, 117 +/- 29; human, 20.4 +/- 3). Furthermore, rhesus monkey sperm-zona binding was reduced by 84% in the presence of rabbit anti-GST-63 antibodies.(ABSTRACT TRUNCATED AT 250 WORDS)

Rhesus monkey oocyte maturation and fertilization in vitro: roles of the menstrual cycle phase and of exogenous gonadotropins

Our objectives were to improve the efficiency of rhesus monkey oocyte maturation and fertilization in vitro and to determine the influence of menstrual cycle phase and exogenous gonadotropins on these processes. Immature oocytes were recovered from antral follicles of ovaries excised from unstimulated animals (n = 14). The highest yield and quality was associated with oocytes obtained from early follicular phase ovaries, and more of these oocytes underwent germinal vesicle breakdown (GVBD; 55%) and matured to metaphase II (MII; 40%) than did oocytes from late follicular (GVBD, 28%; MII, 9%) or luteal (GVBD, 13%; MII, 10%) phase ovaries. Exogenous human (h) FSH and hLH improved GVBD and MII levels for oocytes recovered from late follicular phase ovaries and increased GVBD, but not MII, for oocytes from luteal phase ovaries. MII levels for oocytes from early follicular phase ovaries were adversely affected. Early follicular phase oocytes underwent GVBD faster and attained MII sooner than did those from either late follicular or luteal phase ovaries. Whereas exogenous gonadotropins did not significantly affect oocyte fertilization, follicular phase oocytes tended to be fertilized at a higher rate (p = 0.07). These results demonstrate that higher maturation levels are obtained with oocytes from early follicular phase ovaries and that gonadotropins influence oocyte performance in a cycle phase-dependent manner.

Antibodies to sperm-specific human FA-1 inhibit in vitro fertilization in rhesus monkeys: development of a simian model for testing of anti-FA-1 contraceptive vaccine

The feasibility of using the rhesus monkey as a non-human primate model for testing the efficacy of a contraceptive vaccine based on FA-1 antigen was evaluated. Affinity-purified anti-FA-1 polyclonal antibodies (Fab' fragments) and anti-FA-1 monoclonal antibody were used as probes in these studies. Anti-FA-1 antibodies (polyclonal Fab' as well as monoclonal IgG) predominantly reacted with the postacrosomal, mid-piece and tail regions of rhesus monkey sperm, as with human sperm, by an indirect immunofluorescence technique (IFT). These antibodies also specifically recognized a single protein band of 51 +/- 2 kDa, corresponding to the dimeric form of FA-1 antigen, on a Western blot of lithium diiodosalicylate (LIS)-solubilized monkey sperm. Anti-FA-1 antibodies, when present in the insemination mixture, inhibited the in vitro fertilization (IVF) of monkey oocytes. These results indicate that FA-1 antigen in rhesus monkey sperm is similar in subcellular localization, molecular identity and function to that in human sperm, and that the rhesus monkey represents a permissible non-human primate model in which the efficacy of a contraceptive vaccine based on FA-1 antigen can be tested.

Individualized gonadotropin regimens for follicular stimulation in macaques during in vitro fertilization (IVF) cycles

Follicular stimulation was compared in macaques receiving sequential gonadotropin treatment which was terminated after seven, eight, or nine days depending on the time required to attain preselected criteria of follicular maturation. Although estradiol levels and follicle sizes varied, the number of follicles and oocytes/animal, oocyte nuclear maturity, IVF rates and progesterone levels during the luteal phase were similar among groups. Reducing the duration of gonadotropin treatment to individualize follicular stimulation regimens does not compromise follicle or gamete quality.

Developmental potential of rhesus monkey embryos produced by in vitro fertilization

This study was an examination of the developmental potential of in vitro fertilization (IVF)-produced rhesus monkey embryos that were cultured in medium alone or cocultured with various cell types. End points were the quality and yield of embryos attaining the expanded or hatched blastocyst stage. A total of 96 IVF-produced embryos were cryopreserved and thawed, and 90 embryos were considered intact and suitable for culture. These embryos were placed into one of five treatment groups consisting of four different cell supports and medium alone. Two primary cultures (bovine oviductal cells [bOVID] and bovine cumulus cells [bCUM]) and two established cell lines (Vero cells and buffalo rat liver cells [BRL]) were utilized for coculture of embryos. Embryos were cultured for up to 14 days, and growth curves were established for all embryos that expanded and/or hatched. The developmental rate for embryos classified as viable varied substantially; in number of days to reach a given stage, early morulae ranged from Days 3 to 9 post-insemination, morulae from Days 4 to 9, blastocysts from Days 6 to 11, expanded blastocysts from Days 7 to 12, and hatched blastocysts from Days 9 to 15. On the basis of developmental curves, 30% of the embryos were arrested upon thawing or shortly after. Of the remaining embryos classified as viable, developmental efficiencies to the hatched blastocyst stage for the various treatments were 1) bOVID, 33%; 2) bCUM, 15%; 3) Vero cells, 9%; 4) BRL, 45%; and 5) medium alone, 8%.(ABSTRACT TRUNCATED AT 250 WORDS)

Initiation of periovulatory events in primate follicles using recombinant and native human luteinizing hormone to mimic the midcycle gonadotropin surge

The amplitude and duration of the midcycle LH surge required for periovulatory changes in the primate follicle are incompletely defined. We reported that short (4- to 14-h) LH surges were insufficient to induce periovulatory events after multiple follicular development in macaques. In contrast, an 18- to 24-h LH surge induced oocyte maturation plus granulosa cell luteinization, but did not support corpus luteum function. In this study, the periovulatory changes following LH surges of 48 h elicited using pituitary (pit) or recombinant (r) human (h) LH were compared to those after 24-h LH surge durations or after urinary hCG (u-hCG) treatment. Beginning at menses, rhesus monkeys were treated with human gonadotropins for 9 days to stimulate follicular growth. On day 10, animals (n = 3-5/group) received 1) a single injection of u-hCG [79 +/- 3 micrograms RP-1 equivalents (equiv), im], 2) two injections of pit-hLH (91 +/- 4 micrograms RP-1 equiv, im), 3) one injection of r-hLH (21 +/- 1 micrograms RP-1 equiv, im), or 4) two injections of r-hLH (21 +/- 1 micrograms RP-1 equiv). Oocytes and granulosa cells were obtained via follicle aspiration 27 h after the initial LH or hCG injection. In all groups, serum estradiol rose to similar peak levels by day 10. Circulating LH-like bioactivity was elevated for more than 48 h after u-hCG. Peak serum LH bioactivities were proportional to the administered LH doses, as determined in the in vitro bioassay. Two injections of either r-hLH or pit-hLH elicited surge levels (> 100 ng/mL) of bioactive LH for 36-48 h, whereas one injection sustained surge levels for only 18-24 h. The proportions of oocytes resuming meiosis (68-76%) were similar in all groups. Immunocytochemical staining for progesterone receptor and in vitro progesterone production by granulosa cells in all LH-treated groups were comparable to those of cells form the hCG-treated group. Peak levels of progesterone in the luteal phase were comparable in monkeys treated with two doses of pit-hLH and r-hLH (18.5 +/- 10.4 vs. 8.1 +/- 1.5 ng/mL) and approached that in u-hCG treated monkeys (39.5 +/- 18.0 ng/mL). However, progesterone levels in animals treated once with r-hLH (3.4 +/- 1.5 ng/mL) were less (P < 0.05) than those in u-hCG-treated monkeys.(ABSTRACT TRUNCATED AT 400 WORDS)

Developmental changes in narrative and non-narrative discourse in children with and without brain injury

This study presents a set of narrative and non-narrative tasks and analytic procedures for examining the discourse development of children with perinatal brain injury and typically developing children. Three oral discourse genres were collected at ages 5, 6, and 7: script, picture description, and replica play narration. Genre performances were assessed for the presence of hypothesized genre features. Results suggest these tasks and procedures are able to characterize development in discourse abilities for both a normative group and for children with perinatal brain injury. The group of children with brain injury produced shorter discourse performance with more off-task talk. This group also showed difficulty in fully differentiating the various genre types and in creating integrated discourse performances. However, most of these children demonstrated considerable growth in control of genre features over this time period. The possible utility of these tasks and procedures for clinical assessment is discussed.

Steroid reduction during ovarian stimulation impairs oocyte fertilization, but not folliculogenesis, in rhesus monkeys

OBJECTIVE

To test the hypothesis that steroids locally modulate and may be required for normal follicular function and gametogenesis in primates, the effects of steroid reduction during gonadotropin-stimulated folliculogenesis was studied in rhesus monkeys.

DESIGN

Animals received human FSH (hFSH; days 1 to 6) and hFSH+human LH (hLH; day 7) to promote multiple follicular growth, and then received hCG (day 8) for ovulatory maturation. Four animals received trilostane (3 beta-hydroxysteroid dehydrogenase inhibitor) on days 1 to 8 or no inhibitor (controls; n = 4). Follicles were aspirated 34 hours after hCG.

MAIN OUTCOME MEASURES

Follicular growth, serum E2, P, and pregnenolone, oocyte nuclear maturity, and IVF.

RESULTS

Trilostane markedly reduced E2 to levels as low as 7% of controls throughout the follicular phase. Pregnenolone was 66-fold greater during trilostane treatment relative to controls. In both groups, P was at baseline during follicular stimulation but was reduced for 72 hours after hCG in trilostane-treated animals. Despite E2 suppression, follicular growth and oocyte nuclear maturity were unaltered by trilostane. Trilostane hindered the fertilizability of metaphase II oocytes (15%) in three of four animals compared with controls (65%). Metaphase I oocytes that required > 8 hours to complete meiosis in vitro failed to fertilize in the same three of four receiving trilostane relative to controls (31%).

CONCLUSIONS

Follicular growth and oocyte meiosis did not require high or increasing E2 levels. Levels of follicular products other than E2 may be of value in determining the progress of ovarian stimulation protocols. However, the acquisition of oocyte competence for fertilization may require steroids.