Effects of thyroid hormone on mitochondria and metabolism of human preimplantation embryos

Thyroid hormones are regarded as the major controllers of metabolic rate and oxygen consumption in mammals. Although it has been demonstrated that thyroid hormone supplementation improves bovine embryo development in vitro, the cellular mechanisms underlying these effects are so far unknown. In this study, we investigated the role of thyroid hormone in development of human preimplantation embryos. Embryos were cultured in the presence or absence of 10-7  M triiodothyronine (T3) till blastocyst stage. Inner cell mass (ICM) and trophectoderm (TE) were separated mechanically and subjected to RNAseq or quantification of mitochondrial DNA copy number. Analyses were performed using DESeq (v1.16.0 on R v3.1.3), MeV4.9 and MitoMiner 4.0v2018 JUN platforms. We found that the exposure of human preimplantation embryos to T3 had a profound impact on nuclear gene transcription only in the cells of ICM (1178 regulated genes-10.5% of 11 196 expressed genes) and almost no effect on cells of TE (38 regulated genes-0.3% of expressed genes). The analyses suggest that T3 induces in ICM a shift in ribosome and oxidative phosphorylation activity, as the upregulated genes are contributing to the composition and organization of the respiratory chain and associated cofactors involved in mitoribosome assembly and stability. Furthermore, a number of genes affecting the citric acid cycle energy production have reduced expression. Our findings might explain why thyroid disorders in women have been associated with reduced fertility and adverse pregnancy outcome. Our data also raise a possibility that supplementation of culture media with T3 may improve outcomes for women undergoing in vitro fertilization.

Human stem cells from single blastomeres reveal pathways of embryonic or trophoblast fate specification

Mechanisms of initial cell fate decisions differ among species. To gain insights into lineage allocation in humans, we derived ten human embryonic stem cell lines (designated UCSFB1-10) from single blastomeres of four 8-cell embryos and one 12-cell embryo from a single couple. Compared with numerous conventional lines from blastocysts, they had unique gene expression and DNA methylation patterns that were, in part, indicative of trophoblast competence. At a transcriptional level, UCSFB lines from different embryos were often more closely related than those from the same embryo. As predicted by the transcriptomic data, immunolocalization of EOMES, T brachyury, GDF15 and active β-catenin revealed differential expression among blastomeres of 8- to 10-cell human embryos. The UCSFB lines formed derivatives of the three germ layers and CDX2-positive progeny, from which we derived the first human trophoblast stem cell line. Our data suggest heterogeneity among early-stage blastomeres and that the UCSFB lines have unique properties, indicative of a more immature state than conventional lines.

Behavior and brain gene expression changes in mice exposed to preimplantation and prenatal stress

Preimplantation culture of mouse embryos has been suggested to result in reduced anxiety-like behavior in adulthood. Here, we investigated the effects of in vitro fertilization (IVF), embryo culture, and different diets on anxiety-like behavior using the elevated plus maze (EPM). We hypothesized that exposure to suboptimal conditions during the preimplantation stage would interact with the suboptimal diet to alter behavior. The expression of genes related to anxiety was then assessed by quantitative real-time polymerase chain reaction in various brain regions. When fed a normal diet during gestation and a moderately high-fat Western diet (WD) postnatally, naturally conceived (NC) and IVF mice showed similar anxiety-like behavior on the EPM. However, when fed a low-protein diet prenatally and a high-fat diet postnatally (LP/HF), NC mice showed a modest increase in anxiety-like behavior, whereas IVF mice showed the opposite: a strongly reduced anxiety-like behavior on the EPM. The robust reduction in anxiety-like behavior in IVF males fed the LP/HF diets was, intriguingly, associated with reduced expression of MAO-A, CRFR2, and GABA markers in the hypothalamus and cortex. These findings are discussed in relation to the developmental origin of health and disease hypothesis and the 2-hit model, which suggests that 2 events, occurring at different times in development, can act synergistically with long-term consequences observed during adulthood.

Use of a mouse in vitro fertilization model to understand the developmental origins of health and disease hypothesis

The Developmental Origins of Health and Disease hypothesis holds that alterations to homeostasis during critical periods of development can predispose individuals to adult-onset chronic diseases such as diabetes and metabolic syndrome. It remains controversial whether preimplantation embryo manipulation, clinically used to treat patients with infertility, disturbs homeostasis and affects long-term growth and metabolism. To address this controversy, we have assessed the effects of in vitro fertilization (IVF) on postnatal physiology in mice. We demonstrate that IVF and embryo culture, even under conditions considered optimal for mouse embryo culture, alter postnatal growth trajectory, fat accumulation, and glucose metabolism in adult mice. Unbiased metabolic profiling in serum and microarray analysis of pancreatic islets and insulin sensitive tissues (liver, skeletal muscle, and adipose tissue) revealed broad changes in metabolic homeostasis, characterized by systemic oxidative stress and mitochondrial dysfunction. Adopting a candidate approach, we identify thioredoxin-interacting protein (TXNIP), a key molecule involved in integrating cellular nutritional and oxidative states with metabolic response, as a marker for preimplantation stress and demonstrate tissue-specific epigenetic and transcriptional TXNIP misregulation in selected adult tissues. Importantly, dysregulation of TXNIP expression is associated with enrichment for H4 acetylation at the Txnip promoter that persists from the blastocyst stage through adulthood in adipose tissue. Our data support the vulnerability of preimplantation embryos to environmental disturbance and demonstrate that conception by IVF can reprogram metabolic homeostasis through metabolic, transcriptional, and epigenetic mechanisms with lasting effects for adult growth and fitness. This study has wide clinical relevance and underscores the importance of continued follow-up of IVF-conceived offspring.

Abstract 4895: A cancer stem cell instigator pathway revealed by transcriptomics, stem cell mutagenesis, and in-vivo tumor initiation

We have developed a multi-stage Cancer Stem Cell (CSC) model that recapitulates the natural process of carcinogenesis. Isogenic human embryonic stem cells (ESCs) exposed to non-biased mutagens were found to undergo rare spontaneous CSC transformation. Progenitor induced CSC (iCSC) clones exhibited classical CSC/SC marker expression, tumorsphere formation, resistance to common chemotherapeutic agents, and a capacity to form serially transplantable tumors in immunocompromised animals. A subset of progenitor clones formed tumors that took on a glioma-like morphology and produced more highly drug resistant mature CSCs that exhibited phenotypic characteristics of the primary patient glioma CSCs. Computational comparison to expression profiles of 313 human tumor lines confirmed that the mature CSCs had adopted a glioma-like expression profile.

An integrated molecular model of the instigator pathway was assessed by comprehensive RNASeq transcriptomics, tandem MS proteomics, microRNA profiling, and mutagen-induced molecular polymorphisms. Progenitor iCSCs were found to have an ESC expression phenotype, significantly differing in the expression of only 32 genes, with some bearing direct evidence of mutagenesis in the expressed transcript. The instigator genes formed a proto-oncology seed pathway that was expanded by progressive expression changes to a more classical oncology profile in the glioma-like tumors and mature iCSCs derived in vivo from the progenitor iCSC. Classical oncology targets evident in the late-stage tumor model were absent in the progenitor iCSCs. However, computational repositioning analysis identified a limited set of existing molecules that could act directly to mitigate the progenitor pathway in the iCSCs.

Citation Format: Ana Krtolica, Jacob Glanville, Gnanaratnam Giritharan, Eduardo Caceres, Erica Canino, Kyung-Ah Kim. A cancer stem cell instigator pathway revealed by transcriptomics, stem cell mutagenesis, and in-vivo tumor initiation. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4895. doi:10.1158/1538-7445.AM2013-4895

In vitro culture of mouse embryos reduces differential gene expression between inner cell mass and trophectoderm

Differences in gene expression and imprinting have been reported, comparing in vivo versus in vitro generated preimplantation embryos. Furthermore, mouse studies have shown that placenta development is altered following in vitro culture. However, the molecular mechanisms underlying these findings are unknown. We therefore isolated trophectoderm (TE) and inner cell mass (ICM) cells from in vivo and in vitro fertilization (IVF) embryos and evaluated their transcriptome using microarrays. We found that the transcriptomes of in vitro produced ICM and TE cells showed remarkably few differences compared to ICM and TE cells of in vivo generated embryos. In vitro fertilization embryos showed a reduced number of TE cells compared to in vivo embryos. In addition, TE of IVF embryos showed significant downregulation of solute transporter genes and of genes involved in placenta formation (Eomesodermin, Socs3) or implantation (Hbegf). In summary, IVF and embryo culture significantly affects the transcriptome of ICM and TE cells.

Human embryonic stem cells derived from embryos at different stages of development share similar transcription profiles

We have derived hESC from biopsied blastomeres of cleavage stage embryos under virtually the same conditions we used for the derivation of hESC lines from inner cell mass of blastocyst stage embryos. Blastomere-derived hESC lines exhibited all the standard characteristics of hESC including undifferentiated proliferation, genomic stability, expression of pluripotency markers and the ability to differentiate into the cells of all three germ layers both in vitro and in vivo. To examine whether hESC lines derived from two developmental stages of the embryo differ in gene expression, we have subjected three blastomere-derived hESC lines and two ICM-derived hESC lines grown under identical culture conditions to transcriptome analysis using gene expression arrays. Unlike previously reported comparisons of hESC lines which demonstrated, apart from core hESC-associated pluripotency signature, significant variations in gene expression profiles of different lines, our data show that hESC lines derived and grown under well-controlled defined culture conditions adopt nearly identical gene expression profiles. Moreover, blastomere-derived and ICM-derived hESC exhibited very similar transcriptional profiles independent of the developmental stage of the embryo from which they originated. Furthermore, this profile was evident in very early passages of the cells and did not appear to be affected by extensive passaging. These results suggest that during derivation process cells which give rise to hESC acquire virtually identical stable phenotype and are not affected by the developmental stage of the starting cell population.

Abstract LB-386: Targeting of induced cancer stem cells with iniparib in combination with carboplatin and gemcitabine

BACKGROUND: Mounting evidence exists that human breast cancers include a stem-like cell population with self-renewing, tumorigenic properties. This population of cells, known as cancer stem cells (CSCs) or tumor-initiating cells, shares phenotypic characteristics with embryonic stem cells (ESCs), including activation of certain developmental pathways, and is resistant to many anticancer therapies. Distinguishing features of stem cells include active DNA repair and resistance to apoptosis, which enable their survival in the presence of conventional cytotoxic and cytostatic therapies that target actively proliferating cells. Identification of pharmaceuticals that preferentially target CSCs represents a novel strategy in modern drug discovery and development. We investigated whether treatment with iniparib (BSI-201) can potentiate the anti-proliferative effects of gemcitabine and carboplatin in CSCs.

METHODS: A multi-stage stem cell carcinogenesis model that mirrors the natural progression of carcinogenesis was previously developed using in vitro and in vivo selection of mutated ESCs, which exhibit specific tumor-initiating and cancer stem cell-associated behaviors (SLL Sciences). These induced CSCs (iCSCs) were treated with iniparib (3.7, 11, 33, or 100 μM), gemcitabine (1.5 nM), carboplatin (10 μM), or gemcitabine + carboplatin for 72 hours, and effects on iCSC proliferation were evaluated using an ELISA-based bromodeoxyuridine (BrdU) assay and an ATP-based detection assay for measuring cellular metabolism. Effects of iniparib and/or gemcitabine on DNA damage were evaluated by immunofluorescence staining of iCSC using antibodies against γH2AX (a marker of double strand DNA breaks) at 24 hours after treatment.

RESULTS: Treatment with iniparib alone resulted in a dose-dependent decrease in cellular proliferation and metabolism, with the IC50 established at 60 μM. Iniparib (60 μM), gemcitabine (1.5 nM), and carboplatin (10 μM) each induced >50% reduction in iCSC proliferation; addition of iniparib to gemcitabine resulted in an 80% reduction in BrdU incorporation compared with gemcitabine alone (P = 0.027). To assess iniparib-associated DNA damage, γH2AX foci were quantified in > 300 cells for each treatment combination. Cells treated with iniparib, gemcitabine, or iniparib + gemcitabine demonstrated 3.7-, 6.8-, and 8.8-fold increases in γH2AX foci, respectively, compared with untreated control (P < 0.005).

CONCLUSIONS: These findings demonstrate that iniparib increases the effects of gemcitabine in terms of antiproliferative activity and DNA damage in this CSC model.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-386. doi:10.1158/1538-7445.AM2011-LB-386

Effect of ICSI on gene expression and development of mouse preimplantation embryos

BACKGROUND

In vitro culture (IVC) and IVF of preimplantation mouse embryos are associated with changes in gene expression. It is however not known whether ICSI has additional effects on the transcriptome of mouse blastocysts.

METHODS

We compared gene expression and development of mouse blastocysts produced by ICSI and cultured in Whitten's medium (ICSI(WM)) or KSOM medium with amino acids (ICSI(KSOMaa)) with control blastocysts flushed out of the uterus on post coital Day 3.5 (in vivo). In addition, we compared gene expression in embryos generated by IVF or ICSI using WM. Global pattern of gene expression was assessed using the Affymetrix 430 2.0 chip.

RESULTS

Blastocysts from ICSI fertilization have a reduction in the number of trophoblastic and inner cell mass cells compared with embryos generated in vivo. Approximately 1000 genes are differentially expressed between ICSI blastocyst and in vivo blastocysts; proliferation, apoptosis and morphogenetic pathways are the most common pathways altered after IVC. Unexpectedly, expression of only 41 genes was significantly different between embryo cultured in suboptimal conditions (WM) or optimal conditions (KSOM(aa)).

CONCLUSIONS

Our results suggest that fertilization by ICSI may play a more important role in shaping the transcriptome of the developing mouse embryo than the culture media used.

Derivation of human embryonic stem cell lines from biopsied blastomeres on human feeders with minimal exposure to xenomaterials

In a continuous effort to improve the generation of therapeutic grade human embryonic stem cell (hESC) lines, we focused on preserving developmental capacity of the embryos, minimizing the exposure to xenomaterials, increasing derivation efficacy, and reducing the complexity of the derivation procedure. In this study, we describe an improved method for efficient derivation of hESC lines from blastomeres of biopsied embryos. Our protocol substituted feeder cells of mouse origin with human foreskin fibroblasts (HFFs), limited serum exposure of cells to formation of the initial outgrowth, and increased derivation efficacy from 12.5% (one hESC line out of 13 biopsies) to 50% (3 out of 6 biopsies) by using early population doubling (PD) HFFs. In addition, it eliminated a need for embryo-blastomere coculture, thus reducing the complexity of the culture and enabling continued development of the biopsied embryo under optimal conditions. All derived lines maintained normal karyotype and expressed totipotent phenotype including the ability to differentiate into trophectoderm and all three germ layers.

Pregnancy rates and peripheral progesterone levels following Ovsynch or CIDR ovulation synchronization/timed artificial insemination protocols in postpartum dairy cows

Peripheral progesterone (P4) concentrations as well as pregnancy rates (PR) between cows treated with Ovsynch or CIDR ovulation synchronization/TAI protocols were compared. Two hundred and twenty-seven postpartum lactating Holstein cows were randomly assigned to Ovsynch (n = 111) or CIDR (n = 116) ovulation synchronization/TAI protocols. Pregnancy was diagnosed by ultrasonography at day 35 after TAI and later confirmed by rectal palpation at day 60 post TAI. Milk samples were taken from the beginning of treatment (day -10) until day 35 after TAI (day 0) for P4 determination. Pregnancy rates for Ovsynch and CIDR groups of cows were 31 and 41%, respectively. The PR of ovulation synchronized cows for Ovsynch and CIDR groups were 49 and 69%, respectively. Progesterone levels during the sampling period were similar (P > 0.05) between Ovsynch and CIDR treated cows. Key words: Pregnancy rate, progesterone, Ovsynch, CIDR, cows

Gonadotropin releasing hormone receptor gene and protein expression and immunohistochemical localization in bovine uterus and oviducts

Recently GnRH, GnRH-R systems has been demonstrated in various extrahypothalamic and extrapituitary reproductive tissues in different mammalian species, where GnRH acts in an autocrine and or paracrine manner and modulates different biological processes. GnRH-R mRNA has also been demonstrated in bovine ovaries (follicle and corpus luteum) and normal and carcinogenic human endometrium/endometrial cells. This is the first study elucidating presence of GnRH-R mRNA and GnRH-R protein in bovine uterus and oviducts in follicular and luteal phases of the estrous cycle and further localizing the receptors to endometrial and oviductal epithelial cells. To our knowledge this is the first report demonstrating GnRH-R mRNA and protein in mammalian oviducts. We used gene-specific primers and monoclonal GnRH-R antibody to test GnRH-R mRNA and GnRH-R protein through RT-PCR and immunobloting. Immunohistochemistry was employed to localize these receptors to endometrial and oviductal epithelial cells. GnRH-R mRNA and receptor protein were expressed at expected molecular weights of 920bp and 60kD, respectively. Densitometry analysis revealed that expression levels for GnRH-R protein in uterus and oviducts were similar to bovine pituitary. The presence of GnRH receptors in bovine uterus and oviducts is intriguing and it would be imperative to examine the functional role of this system in the regulation of reproductive processes.

Effect of in vitro fertilization on gene expression and development of mouse preimplantation embryos

In vitro culture (IVC) of preimplantation mouse embryos is associated with changes in gene expression. It is however, not known if the method of fertilization affects the global pattern of gene expression. We compared gene expression and development of mouse blastocysts produced by in vitro fertilization (IVF) versus blastocysts fertilized in vivo and cultured in vitro from the zygote stage (IVC) versus control blastocysts flushed out of the uterus on post coital day 3.5. The global pattern of gene expression was assessed using the Affymetrix 430 2.0 chip. It appears that each method of fertilization has a unique pattern of gene expression and development. Embryos cultured in vitro had a reduction in the number of trophoblastic cells (IVF 33.5 cells, IVC 39.9 cells, and 49.6 cells in the in vivo group) and, to a lesser degree, of inner cell mass cells (12.8, 11.7, and 13.8 respectively). The inner cell mass nuclei were larger after culture in vitro (140 microm(2), 113 microm(2), and 86 microm(2) respectively). Although a high number of genes (1912) was statistically different in the IVF cohort when compared with the in vivo control embryos, the magnitude of the changes in gene expression were low and only a minority of genes (29 genes) was changed more than fourfold. Surprisingly, IVF embryos were different from IVC embryos (3058 genes were statistically different, but only three changed more than fourfold). Proliferation, apoptosis, and morphogenetic pathways are the most common pathways altered after IVC. Overall, IVF and embryo culture have a profound effect on gene expression pattern and phenotype of mouse preimplantation embryos.

Paternal influence on apoptosis, and expression of BCL2, BAX, TP53, heat shock protein-70 and interferon tau genes in bovine preimplantation embryo

The bull effects on apoptosis, and BAX, BCL2, TP53, heat shock protein 70 (HSPA1A) and interferon tau (IFNT) gene expression in in vitro produced embryos were investigated. The degree of correlation of this effect with the 60- to 90-d non-return rates was also investigated. Standard in vitro fertilization and embryo culture were performed using frozen semen from six genetically unrelated bulls. Live, apoptotic, and dead cell percentages in blastocysts were determined, after staining with annexin V, propidium iodide, and bisbenzamide. BAX, BCL2, TP53, HSPA1A and IFNT gene expression levels in blastocysts were determined by RT-PCR. The non-return rate data for all experimental bulls were obtained from a local artificial insemination center. Apoptotic, live and dead blastomere percentages, and HSPA1A and IFNT expression levels in blastocysts were different (P < 0.01) among bulls. BAX, BCL2 and TP53 expression levels were not different among bulls. The non-return rate was highly correlated (P < 0.05) with BCL2 (r = -0.93) or the ratio of BAX to BCL2 (r = 0.84) gene expression. None of the other in vitro fertility parameters were correlated with non-return rate. This study concluded that the development, apoptosis, and HSPA1A and IFNT gene expression of in vitro produced embryos are influenced by individual bulls. Key words: Bovine, embryo, fertility, apoptosis, gene expression, interferon

Effects of oxygen tension on gene expression in preimplantation mouse embryos

OBJECTIVE

To compare the effects of atmospheric and physiologic oxygen concentrations on the global patterns of gene expression during mouse preimplantation development.

DESIGN

Comparative analysis of in vivo-produced and in vitro-produced embryos.

SETTING

Research laboratory.

PATIENT(S)

None.

INTERVENTION(S)

Control embryos at the blastocyst stage that developed in vivo were collected from uteri. Experimental embryos were obtained at the zygote stage and cultured to the blastocyst stage in Whitten's medium or KSOM medium with amino acids under 20% oxygen (atmospheric) or 5% oxygen (physiologic).

MAIN OUTCOME MEASURE(S)

Embryo development, cell number, and gene expression assayed by microarray technology.

RESULT(S)

Low (physiologic) oxygen concentration is associated with faster embryo development and increased cell number. In addition, there are marked perturbations in the global pattern of gene expression, as assessed by oligonucleotide microarray, after culture in 20% oxygen as compared with 5% oxygen.

CONCLUSION(S)

Culture in low oxygen is associated with fewer perturbations in the global pattern of gene expression and more closely resembles that of the in vivo control embryos. These findings provide rationale for culturing human embryos in the presence of 5%, rather than 20%, oxygen.

Development of in vitro tests to predict fertility of bulls

The overall objective was to develop an in vitro test to predict fertility of bulls in the field. We investigated the bull effect on in vitro embryo production, zona binding and acrosome reaction, and the correlation of this effect to field fertility meas ured by 60–90 d non-return rate. Frozen semen from three separate ejaculates of eight unrelated young bulls, obtained from an artificial insemination (AI) center, was used. On thawing, ejaculates from each bull were pooled, motile sperm were selected and (a) subjected to immunofluorescent assay at 0 and 4 h of incubation in capacitation medium to assess acrosome status, (b) used in an in vitro fertilization assay system to assess cleavage and blastocyst production rates, and (c) sperm-zona binding assay was carried out to determine the number of sperm bound to the zona pellucida of mature oocytes. Percentage of pre-freeze motile sperm (PrFM) and non-return rate data were obtained from the AI center. PrFM, percentage of acrosome reacted sperm at 0 h (AR1), increase in percentage of acrosome reacted sperm after 4 h (InAR) and sperm-zona binding rates (ZB) differed (P < 0.05) among sperm samples obtained from different young bulls. Significant correlations (P < 0.05) were observed between PrFM and AR1 (r = -0.31), InAR (r = 0.36), and ZB (r = 0.32). AR1 was negatively correlated to ZB (r = -0.27) and cleavage rate (r = -0.20), InAR was positively correlated with ZB (r = 0.31) and cleavage rate (r = 0.26). None of the in vitro tests was correlated with non-return rate. These findings indicate that along with pre-freeze motility, a combination of in vitro tests including the percentage of spontaneously acrosome reacted sperm at thawing, might be useful in predicting bull field fertility. Such a combination of assays, however, has yet to be determined. Key words: Field fertility, acrosome reaction, zona binding, IVF, fertility assay

In vitro assessment of corpus luteum function in cattle following Ovsynch and CIDR ovulation synchronization protocols

Non-lactating beef cows (N = 40) were used to determine in vitro production of progesterone by CLs collected on days 6–8, 13–15 and 19–20, following Ovsynch or CIDR ovulation synchronization protocols. Progesterone released by the CL tissues into the medium was measured after 1 h of incubation (control) and after 6 h of hormone treatments (LH, PGF2α or LH + PGF2α). In vitro progesterone production did not differ (P > 0.05) between Ovsynch and CIDR ovulation synchronization protocols. Pooled data, irrespective of ovulation synchronization treatments, showed interaction (P < 0.05) between hormone treatment and stage of CL. Key words: Corpus luteum, progesterone, cows, ovulation synchronization

GnRH receptor messenger ribonucleic acid expression in bovine ovary

The present study was undertaken to investigate the mRNA expression for gonadotropin-releasing hormone (GnRH) receptor in bovine ovary. Granulosa cells from small (< 4 mM), medium (5–8 mM) and large follicles (> 8 mM) and tissues from corpora lutea (CL) of different stages: Stage I (days 1–4), Stage II (days 5–10), Stage III (days 11–17), and Stage IV (days 18–21, days after ovulation) were harvested from bovine ovaries collected at a local abattoir. The mRNA isolated from representative samples was subjected to reverse transcription-polymerase chain reaction (RT-PCR) using gene sequence specific primers. The resultant PCR amplified gonadotropin-releasing horm one receptor (GnRH-R) cDNA products were identified and confirmed through Southern blot hybridization and nucleotide sequence analysis, respectively. The results showed the presence of GnRH-R mRNA transcripts in both follicles and CL. Key words: Bovine, granulosa cells, corpus luteum, GnRH receptor, mRNA

In vitro embryo production using ovaries removed from culled cows

The objective was to utilize in vitro maturation and fertilization to maximize embryo production from culled dairy cows. Ovaries were removed (via a colopotomy technique) from culled Holstein cows (n = 21) 2 d after standing estrus (T1), 2 d after treatment with 40 mg follicle stimulating hormone (FSH) given at standing estrus (T2), or at an unknown stage of the estrous cycle (T3).Treatment with FSH increased (P < 0.05) oocyte recovery rate (mean ± SEM, 14.6 ± 2.2, 25.4 ± 3.4, and 11.1 ± 2.6 oocytes ovary–1), for groups T1, T2 and T3, respectively, and the number of blastocysts obtained (1.6 ± 0.5, 4.4 ± 0.4 and 1.6 ± 0.6 blastocysts ovary–1). Culled dairy cows of high genetic merit are potential embryo donors, with an average of six to eight transferable embryos obtained from each FSH-treated cow. Key words: FSH treatment, oocyte recovery, IVM, IVF, culled cows