The potential effect of melatonin on in vitro oocyte maturation and embryo development in animals

Melatonin is a hormone mainly secreted by the pineal gland during the circadian cycle, with low levels during the daytime and prominent levels during the night. It is involved in numerous physiological functions including the immune system, circadian rhythm, reproduction, fertilization, and embryo development. In addition, melatonin exerts anti-inflammatory and antioxidant effects inside the body by scavenging reactive oxygen and reactive nitrogen species, increasing antioxidant defenses, and blocking the transcription factors of pro-inflammatory cytokines. Its protective activity has been reported to be effective in various reproductive biotechnological processes, including in vitro maturation (IVM), embryo development, and survival rates. In this comprehensive review, our objective is to summarize and debate the potential mechanism and impact of melatonin on oocyte maturation and embryo development through various developmental routes in different mammalian species.

Genome-wide identification and evolutionary analysis of the FGF gene family in buffalo

Fibroblast growth factors (FGFs) are important polypeptide growth factors that play a critical role in many developmental processes, including differentiation, cell proliferation, and migration in mammals. This study employs in silico analyses to characterize the FGF gene family in buffalo, investigating their genome-wide identification, physicochemical properties, and evolutionary patterns. For this purpose, genomic and proteomic sequences of buffalo, cattle, goat, and sheep were retrieved from NCBI database. We identified a total of 22 FGF genes in buffalo. Physicochemical properties observed through ProtParam tool showed notable features of these proteins including in-vitro instability, thermostability, hydrophilicity, and basic nature. Phylogenetic analysis grouped 22 identified genes into nine sub-families based on evolutionary relationships. Additionally, analysis of gene structure, motif patterns, and conserved domains using TBtools revealed the remarkable conservation of this gene family across selected species throughout the course of evolution. Comparative amino acid analysis performed through ClustalW demonstrated significant conservation between buffalo and cattle FGF proteins. Mutational analysis showed three non-synonymous mutations at positions R103 > G, P7 > L, and E98 > Q in FGF4, FGF6, and FGF19, respectively in buffalo. Duplication events revealed only one segmental duplication (FGF10/FGF22) in buffalo and two in cattle (FGF10/FGF22 and FGF13/FGF13-like) with Ka/Ks values <1 indicating purifying selection pressure for these duplications. Comparison of protein structures of buffalo, goat, and sheep exhibited more similarities in respective structures. In conclusion, our study highlights the conservation of the FGF gene family in buffalo during evolution. Furthermore, the identified non-synonymous mutations may have implications for the selection of animals with better performance.Communicated by Ramaswamy H. Sarma.

Effects of EGF and melatonin on gene expression of cumulus cells and further in vitro embryo development in bovines

Despite previous research demonstrating the benefits of including growth factors and antioxidants to maturation medium to support embryo production, to date the effect of epidermal growth factor (EGF) and melatonin (Mel) on oocyte competency has not been studied. This study supplemented in vitro maturation (IVM) medium with EGF (10 ng/ml) and Mel (50 ng/ml) alone, or in combination, and evaluated cumulus cell (CC) gene expression and the development and quality of parthenogenetic blastocysts. No differences in CC gene expression levels indicative of developmental potential were found among the treatment groups. Antioxidant gene CuZnSOD was significantly (P < 0.05) decreased in CCs from the Mel group. Moreover, blastocyst rates on day 7 were significantly increased in EGF or Mel (P < 0.05), but not EGF+Mel. Significant decrease (P < 0.05) in GPX1, CuZnSOD, SLC2A1 and HSPA1A (P = 0.07) mRNA levels was observed in blastocysts from the Mel group. OCT4 gene expression was significantly increased (P < 0.05) in EGF+Mel and confirmed using immunofluorescence. Our results indicate that, despite the lack of changes of competence-related genes in CCs, IVM medium supplemented with Mel improved the culture environment sufficiently, resulting in improved blastocysts. Moreover, EGF and Mel combined during maturation increased OCT4 gene and protein expression in blastocysts, indicating its potential for stem cells.

Comparative Transcriptome Analyses during the Vegetative Cell Cycle in the Mono-Cellular Organism Pseudokeronopsis erythrina (Alveolata, Ciliophora)

Studies focusing on molecular mechanisms of cell cycles have been lagging in unicellular eukaryotes compared to other groups. Ciliates, a group of unicellular eukaryotes, have complex cell division cycles characterized by multiple events. During their vegetative cell cycle, ciliates undergo macronuclear amitosis, micronuclear mitosis, stomatogenesis and somatic cortex morphogenesis, and cytokinesis. Herein, we used the hypotrich ciliate Pseudokeronopsis erythrina, whose morphogenesis has been well studied, to examine molecular mechanisms of ciliate vegetative cell cycles. Single-cell transcriptomes of the growth (G) and cell division (D) stages were compared. The results showed that (i) More than 2051 significantly differentially expressed genes (DEGs) were detected, among which 1545 were up-regulated, while 256 were down-regulated at the D stage. Of these, 11 randomly picked DEGs were validated by reverse transcription quantitative polymerase chain reaction (RT-qPCR); (ii) Enriched DEGs during the D stage of the vegetative cell cycle of P. erythrina were involved in development, cortex modifications, and several organelle-related biological processes, showing correspondence of molecular evidence to morphogenetic changes for the first time; (iii) Several individual components of molecular mechanisms of ciliate vegetative division, the sexual cell cycle and cellular regeneration overlap; and (iv) The P. erythrina cell cycle and division have the same essential components as other eukaryotes, including cyclin-dependent kinases (CDKs), cyclins, and genes closely related to cell proliferation, indicating the conserved nature of this biological process. Further studies are needed focusing on detailed inventory and gene interactions that regulate specific ciliated cell-phase events.

Effect of Sex of Embryo on Developmental Competence, Epigenetic Status, and Gene Expression in Buffalo (Bubalus bubalis) Embryos Produced by Hand-Made Cloning

Buffalo embryos were produced by hand-made cloning using skin fibroblasts from male and female buffaloes (n = 4 each) as donor cells for examining the effect of sex. Although the rate of blastocyst formation (43.8% ± 1.31% vs. 42.2% ± 1.22%) was similar, the total cell number (333 ± 10.4 vs. 270 ± 10.9) was higher (p < 0.05) whereas the apoptotic index (6.39 ± 0.25 vs. 8.52 ± 0.38) was lower (p < 0.05) for male than for female blastocysts. In the blastocysts, the global level of H3K18ac was found to be in the following order: male>female>IVF (in vitro fertilization) blastocysts (p < 0.05). The global level of H3K9me2 was not significantly different between male and female blastocysts and was higher (p < 0.05) compared with that in their IVF counterparts. The relative mRNA abundance of X-chromosome-linked (XIST, HPRT, PGK, and G6PD), apoptosis- (CASPASE3) and pregnancy-related genes (IFN-τ) was significantly higher (p < 0.05) whereas that of DNMT1 was significantly lower (p < 0.05) in female than in male blastocysts; however, in the case of apoptosis- (BCL-XL) and developmental competence-related genes (IGF1R and OCT4), the expression level was similar between the two groups. The gene expression level of OCT4 and IFN-τ but not of IGF1R was significantly lower (p < 0.05) in cloned than in IVF blastocysts. This study demonstrates that the epigenetic status, quality, and expression level of several genes but not the developmental competence are affected by the sex of cloned embryos.

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

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

Differential expression pattern of key regulatory developmental genes in pre-implant zona free cloned vs in vitro fertilized goat embryos

The success of Somatic cell nuclear transfer (SCNT) primarily depends on the extent of reprogramming of donor cells genome. The error of reprogramming may lead to inappropriate expression of embryonic genes at any stage of development. Under the present study the relative expression of different genes related to pluripotency (Oct-4 and Nanog), growth factors (IGF-2 and IGF-2R) and DNA methyltransferase gene (Dnmt-1) was evaluated in SCNT embryos at 8-16 cells, morula and blastocyst stages as compared to IVF group. In SCNT, significantly higher degree of relative expression was observed for Oct-4 in morula (1.41) and blastocysts (1.14) as compared to 8-16 cells (referral stage) whereas in IVF, a lower expression was observed at morula (0.82) stage. The expression of Nanog in SCNT embryos was increased significantly in morula (2.23) and decreased subsequently in blastocyst (0.56), whereas it was increased significantly from 8 to 16 cells to morula (1.62) and blastocyst (4.5) of IVF group. The IGF-2 and IGF-2R showed significantly higher expression rates in morula and blastocysts of SCNT (6.56, 5.90 and 1.11, 1.4) and IVF (8.69, 8.25 and 2.96, 3.91) embryos, respectively as compared to referral stage. The expression of Dnmt-1 was significantly higher in SCNT morula (1.29) and blastocyst (1.15) however in IVF, it was similar in 8-16 cells stage and morula but, higher in blastocyst (1.58). The dissimilar pattern of gene expression of SCNT might be a consequence of incomplete reprogramming of donor nucleus which resulted into lower blastocyst rate of SCNT as compared to IVF embryos.

Developmental competence and expression profile of genes in buffalo (Bubalus bubalis) oocytes and embryos collected under different environmental stress

The study examined the effects of different environmental stress on developmental competence and the relative abundance (RA) of various gene transcripts in oocytes and embryos of buffalo. Oocytes collected during cold period (CP) and hot period (HP) were matured, fertilized and cultured in vitro to blastocyst hatching stage. The mRNA expression patterns of genes implicated in developmental competence (OCT-4, IGF-2R and GDF-9), heat shock (HSP-70.1), oxidative stress (MnSOD), metabolism (GLUT-1), pro-apoptosis (BAX) and anti-apoptosis (BCL-2) were evaluated in immature and matured oocytes as well as in pre-implantation stage embryos. Oocytes reaching MII stage, cleavage rates, blastocyst yield and hatching rates increased (P < 0.05) during the CP. In MII oocytes and 2-cell embryos, the RA of OCT-4, IGF-2R, GDF-9, MnSOD and GLUT-1 decreased (P < 0.05) during the HP. In 4-cell embryos, the RA of OCT-4, IGF-2R and BCL-2 decreased (P < 0.05) in the HP, whereas GDF-9 increased (P < 0.05). In 8-to 16-cell embryos, the RA of OCT-4 and BCL-2 decreased (P < 0. 05) in the HP, whereas HSP-70.1 and BAX expression increased (P < 0.05). In morula and blastocyst, the RA of OCT-4, IGF-2R and MnSOD decreased (P < 0.05) during the HP, whereas HSP-70.1 was increased (P < 0.05). In conclusion, deleterious seasonal effects induced at the GV-stage carry-over to subsequent embryonic developmental stages and compromise oocyte developmental competence and quality of developed blastocysts.

Differences in developmental competence and gene expression profiles between buffalo (Bubalus bubalis) preimplantation embryos cultured in three different embryo culture media

The objective of this study was to compare effects of in vitro culture systems on embryonic development and expression patterns of developmentally important genes in preimplantation buffalo embryos. After IVM/IVF presumptive zygotes were cultured in one of three systems: undefined TCM-199, mCR2aa medium supplemented with 10 % FBS and defined PVA-myo-inositol-phosphate-EGF medium. No (P > 0.05) differences at 2-cell, 4-cell and 8-cell to 16- cell stages were observed among the three cultured media used, however, increased (P < 0.05) blastocyst yield, cell number and hatching rate were found in defined medium compared to undefined media. The expression patterns of genes implicated in embryo metabolism (GLUT-1), anti-apoptosis (BCL-2), imprinting (IGF-2R), DNA methylation (DNMT-3A) and maternal recognition of pregnancy (IFNT) were increased (P < 0.05) in hatched blastocysts derived from defined medium compared to undefined media. In conclusion, serum-free, defined medium improved developmental competence of in vitro cultured buffalo embryos. Whether these differences in morphological development and gene expression have long-term effects on buffalo calves born after embryo transfer remains unknown. However, it is possible that early adaptations of the preimplantation embryo to its environment persist during fetal and post-natal development.

Effects of Two Types of Melatonin-Loaded Nanocapsules with Distinct Supramolecular Structures: Polymeric (NC) and Lipid-Core Nanocapsules (LNC) on Bovine Embryo Culture Model

Melatonin has been used as a supplement in culture medium to improve the efficiency of in vitro produced mammalian embryos. Through its ability to scavenge toxic oxygen derivatives and regulate cellular mRNA levels for antioxidant enzymes, this molecule has been shown to play a protective role against damage by free radicals, to which in vitro cultured embryos are exposed during early development. In vivo and in vitro studies have been performed showing that the use of nanocapsules as active substances carriers increases stability, bioavailability and biodistribution of drugs, such as melatonin, to the cells and tissues, improving their antioxidant properties. These properties can be modulated through the manipulation of formula composition, especially in relation to the supramolecular structures of the nanocapsule core and the surface area that greatly influences drug release mechanisms in biological environments. This study aimed to evaluate the effects of two types of melatonin-loaded nanocapsules with distinct supramolecular structures, polymeric (NC) and lipid-core (LNC) nanocapsules, on in vitro cultured bovine embryos. Embryonic development, apoptosis, reactive oxygen species (ROS) production, and mRNA levels of genes involved in cell apoptosis, ROS and cell pluripotency were evaluated after supplementation of culture medium with non-encapsulated melatonin (Mel), melatonin-loaded polymeric nanocapsules (Mel-NC) and melatonin-loaded lipid-core nanocapsules (Mel-LNC) at 10⁻⁶, 10⁻⁹, and 10⁻¹² M drug concentrations. The highest hatching rate was observed in embryos treated with 10⁻⁹ M Mel-LNC. When compared to Mel and Mel-NC treatments at the same concentration (10⁻⁹ M), Mel-LNC increased embryo cell number, decreased cell apoptosis and ROS levels, down-regulated mRNA levels of BAX, CASP3, and SHC1 genes, and up-regulated mRNA levels of CAT and SOD2 genes. These findings indicate that nanoencapsulation with LNC increases the protective effects of melatonin against oxidative stress and cell apoptosis during in vitro embryo culture in bovine species.

Melatonin delivery by nanocapsules during in vitro bovine oocyte maturation decreased the reactive oxygen species of oocytes and embryos

In this work, a promising approach to increase the advantageous properties of melatonin through its encapsulation into lipid-core nanocapsules (LNC) was examined. Oocytes were treated during in vitro maturation with non-encapsulated melatonin (Mel), melatonin-loaded lipid-core nanocapsules (Mel-LNC), and unloaded LNC. Cytotoxicity, meiotic maturation rate, development to the blastocyst stage, reactive oxygen species (ROS) and glutathione levels, mean cell number and apoptotic cell/blastocyst, and mRNA quantification were evaluated. Both Mel and Mel-LNC enhanced in vitro embryo production, however, Mel-LNC proved to be more effective at decreasing ROS levels and the apoptotic cell number/blastocyst, increasing the cleavage and blastocyst rates, up-regulating the GPX1 and SOD2 genes, and down-regulating the CASP3 and BAX genes. Mel-LNC could penetrate into oocytes and remain inside the cells until they reach the blastocyst stage. In conclusion, when melatonin was encapsulated in LNC and applied during in vitro oocyte maturation, some quality aspects of the blastocysts were improved.

Differential developmental competence and gene expression patterns in buffalo (Bubalus bubalis) nuclear transfer embryos reconstructed with fetal fibroblasts and amnion mesenchymal stem cells

The developmental ability and gene expression pattern at 8- to 16-cell and blastocyst stages of buffalo (Bubalus bubalis) nuclear transfer (NT) embryos from fetal fibroblasts (FFs), amnion mesenchymal stem cells (AMSCs) and in vitro fertilized (IVF) embryos were compared in the present studies. The in vitro expanded buffalo FFs showed a typical "S" shape growth curve with a doubling time of 41.4 h and stained positive for vimentin. The in vitro cultured undifferentiated AMSCs showed a doubling time of 39.5 h and stained positive for alkaline phosphatase, and these cells also showed expression of pluripotency markers (OCT 4, SOX 2, NANOG), and mesenchymal stem cell markers (CD29, CD44) and were negative for haematopoietic marker (CD34) genes at different passages. Further, when AMSCs were exposed to corresponding induction conditions, these cells differentiated into adipogenic, chondrogenic and osteogenic lineages which were confirmed through oil red O, alcian blue and alizarin staining, respectively. Donor cells at 3-4 passage were employed for NT. The cleavage rate was significantly (P < 0.05) higher in IVF than in FF-NT and AMSC-NT embryos (82.6 ± 8.2 vs. 64.6 ± 1.3 and 72.3 ± 2.2 %, respectively). However, blastocyst rates in IVF and AMSC-NT embryos (30.6 ± 2.7 and 28.9 ± 3.1 %) did not differ and were significantly (P < 0.05) higher than FF-NT (19.5 ± 1.8 %). Total cell number did not show significant (P > 0.05) differences between IVF and AMSC-NT embryos (186.7 ± 4.2, 171.2 ± 3.8, respectively) but were significantly (P < 0.05) higher than that from FF-NT (151.3 ± 4.1). Alterations in the expression pattern of genes implicated in transcription and pluripotency (OCT4, STAT3, NANOG), DNA methylation (DNMT1, DNMT3A), histone deacetylation (HDAC2), growth factor signaling and imprinting (IGF2, IGF2R), apoptosis (BAX, BCL2), metabolism (GLUT1) and oxidative stress (MnSOD) regulation were observed in cloned embryos. The transcripts or expression patterns in AMSC-NT embryos more closely followed that of the in vitro derived embryos compared with FF-NT embryos. The results demonstrate that multipotent amnion MSCs have a greater potential as donor cells than FFs in achieving enhanced production of cloned buffalo embryos.

Transcriptomic Features of Bovine Blastocysts Derived by Somatic Cell Nuclear Transfer

Reprogramming incompletely occurs in most somatic cell nuclear transfer (SCNT) embryos, which results in misregulation of developmentally important genes and subsequent embryonic malfunction and lethality. Here we examined transcriptome profiles in single bovine blastocysts derived by in vitro fertilization (IVF) and SCNT. Different types of donor cells, cumulus cell and ear-skin fibroblast, were used to derive cSCNT and fSCNT blastocysts, respectively. SCNT blastocysts expressed 13,606 genes on average, similar to IVF (13,542). Correlation analysis found that both cSCNT and fSCNT blastocyst groups had transcriptomic features distinctive from the IVF group, with the cSCNT transcriptomes closer to the IVF ones than the fSCNT. Gene expression analysis identified 56 underrepresented and 78 overrepresented differentially expressed genes in both SCNT groups. A 400-kb locus harboring zinc-finger protein family genes in chromosome 18 were found coordinately down-regulated in fSCNT blastocysts, showing a feature of reprogramming-resistant regions. Probing into different categories of genes important for blastocyst development revealed that genes involved in trophectoderm development frequently were underrepresented, and those encoding epigenetic modifiers tended to be overrepresented in SCNT blastocysts. Our effort to identify reprogramming-resistant, differentially expressed genes can help map reprogramming error-prone loci onto the genome and elucidate how to handle the stochastic events of reprogramming to improve cloning efficiency.

A comparative study on expression profile of developmentally important genes during pre-implantation stages in buffalo hand-made cloned embryos derived from adult fibroblasts and amniotic fluid derived stem cells

Abnormal gene expression in somatic cell nuclear transfer embryos due to aberrant epigenetic modifications of the donor nucleus may account for much of the observed diminished viability and developmental abnormalities. The present study compared the developmentally important gene expression pattern at 4-cell, 8- to 16-cell, morula, and blastocyst stages of buffalo nuclear transfer (NT) embryos from adult fibroblasts (AFs) and amniotic fluid stem cells (AFSCs). In vitro fertilized embryos were used as control embryos. Alterations in the expression pattern of genes implicated in transcription and pluripotency (OCT4, STAT3, NANOG), DNA methylation (DNMT1, DNMT3A), histone deacetylation (HDAC2), growth factor signaling, and imprinting (IGF2, IGF2R), apoptosis (BAX, BCL2), oxidative stress (MnSOD), metabolism (GLUT1) regulation were observed in cloned embryos. The expression of transcripts in AFSC-NT embryos more closely followed that of the in vitro fertilized embryos compared with AF-NT embryos. It is concluded that AFSCs with a relatively undifferentiated genome may serve as suitable donors which could be reprogrammed more efficiently to reactivate expression of early embryonic genes in buffalo NT.

Assessment of difference in gene expression profile between embryos of different derivations

Researchers have exerted sustained efforts to improve the viability of somatic cell nuclear transfer (SCNT) embryos, testing their experimental designs and probing the resultant embryos. However, the lack of a reliable method to estimate the efficacy of these experimental attempts is a chief hindrance to tackling the low-viability problem in SCNT. Here, we introduce a procedure that assesses the degree of difference in gene expression profiles (GEPs) of blastocysts from each other as a representative control of good quality. We first adapted a multiplex reverse transcription-polymerase chain reaction strategy to obtain GEPs for 15 reprogramming-related genes from single mouse blastocysts. GEPs of individual blastocysts displayed a broad range of variations, the extent of which was calculated using a weighted root mean square deviation (wRMSD). wRMSD-based quantitation of GEP difference (qGEP) found that GEP difference between in vivo-derived blastocysts (in vivo) and SCNT blastocysts was greater than the difference between in vivo blastocysts and in vitro-produced (IVP) blastocysts, demonstrating that the SCNT group was more distantly related to the in vivo group than the IVP group. Our qGEP approach for grading individual blastocysts would be useful for selecting a better protocol to derive embryos of better quality prior to field applications.

Expression profile of developmentally important genes between hand-made cloned buffalo embryos produced from reprogramming of donor cell with oocytes extract and selection of recipient cytoplast through brilliant cresyl blue staining and in vitro fertilized embryos

PURPOSE

To compare the expression profile of developmentally important genes between hand-made cloned buffalo embryos produced from reprogramming of donor cell with oocyte extracts and selection of recipient cytoplast through brilliant cresyl blue staining and in vitro fertilized (IVF) embryos.

METHODS

Hand-made cloned embryos were produced using oocyte extracts treated donor cells and brilliant cresyl blue (BCB) stained recipient cytoplasts. IVF embryos were produced by culturing 15-20 COCs in BO capacitated sperms from frozen thawed buffalo semen and the mRNA expression patterns of genes implicated in metabolism (GLUT1), pluripotency (OCT4), DNA methylation (DNMT1), pro- apoptosis (BAX) and anti-apoptosis (BCL2) were evaluated at 8- to16- cell stage embryos.

RESULTS

A significantly (P < 0.05) higher number of 8- to16- cell and blastocyst stages (73.9 %, 32.8 %, respectively) were reported in hand-made cloning (HMC) as compared to in vitro fertilization (49.2 %, 24.2 %, respectively). The amount of RNA recovered from 8- to 16- cell embryos of HMC and in vitro fertilization did not appear to be influenced by the method of embryo generation (3.76 ± 0.61 and 3.82 ± 0.62 ng/μl for HMC and in vitro fertilization embryos, respectively). There were no differences in the expression of the mRNA transcripts of genes (GLUT1, OCT4, DNMT1, BAX and BCL2) were analysed by real-time PCR between hand-made cloned and IVF embryos.

CONCLUSIONS

Pre-treatment of donor cells with oocyte extracts and selection of developmentally competent oocytes through BCB staining for recipient cytoplast preparations may enhance expression of developmentally important genes GLUT1, OCT4, DNMT1, BAX, and BCL2 in hand-made cloned embryos at levels similar to IVF counterparts. These results also support the notion that if developmental differences observed in HMC and in vitro fertilization produced foetuses and neonates are the results of aberrant gene expression during the pre-implantation stage, those differences in expression are subtle or appear after the maternal to zygotic transition stage of development.

Generation of aminoterminally truncated, stable types of bioactive bovine and porcine fibroblast growth factor 4 in Escherichia coli

Fibroblast growth factor 4 (FGF4) is a crucial growth factor for the development of mammalian embryos. We previously produced hexahistidine-tagged, bovine and porcine FGF4 (Pro(32) to Leu(206) ) proteins without a secretory signal peptide at the aminoterminus in Escherichia coli. Here, we found that these were unstable; site-specific cleavage between Ser(54) and Leu(55) in both FGF4 derivatives was identified. In order to generate stable FGF4 derivatives and to investigate their biological activities, aminoterminally truncated and hexahistidine-tagged bovine and porcine FGF4 (Leu(55) to Leu(206) ) proteins, termed HisbFGF4L and HispFGF4L, respectively, were produced in E. coli. These FGF4 derivatives were sufficiently stable and exerted mitogenic activities in fibroblasts. Treatment with the FGF4 derivatives promoted the phosphorylation of ERK1/2, which are crucial kinases in the FGF signaling pathway. In the presence of PD173074, an FGF receptor inhibitor, the phosphorylation of ERK1/2 was inhibited and resulted in abolition of the growth-promoting activity of FGF4 derivatives. Taken together, we demonstrate that HisbFGF4L and HispFGF4L are capable of promoting the proliferation of bovine- and porcine-derived cells, respectively, via an authentic FGF signaling pathway. These FGF4 derivatives may be applicable for dissecting the roles of FGF4 during embryogenesis in cattle and pigs.

Resveratrol treatment during goat oocytes maturation enhances developmental competence of parthenogenetic and hand-made cloned blastocysts by modulating intracellular glutathione level and embryonic gene expression

PURPOSE

The aim of the present study was to determine whether supplementation of resveratrol, a stilbenoid antioxidant with therapeutic significance, influences goat (Capra hircus) oocyte maturation and subsequent embryonic development and expression of apoptosis and early embryonic development-related genes.

METHODS

Five different concentrations of resveratrol (0.1, 0.25, 0.5, 2.0 and 5.0 μM) were used in in vitro maturation (IVM) medium. Cell tracker blue and 2',7'-dichlorodihydrofluorescein diacetate (H2DCFDA) fluorescent stains were used to assay intracellular glutathione and reactive oxygen species levels in mature oocytes. Parthenogenetic activation and hand-made cloning were performed to check the developmental potential following resveratrol treatment. We used quantitative real-time PCR to analyze embryonic gene expression.

RESULT

Compared to control, no significant improvement was observed in nuclear maturation in resveratrol-treated groups and at 5.0 μM concentration maturation rate decreased significantly (P < 0.05). But resveratrol treatment at the concentrations of 0.25, 0.5 μM significantly reduced intracellular ROS, and increased GSH concentrations. Oocytes treated with 0.25, 0.5 μM resveratrol when subsequently used for PA and HMC, higher extent of blastocyst yields were observed. Expression analysis of proapoptotic (Bax) gene in mature oocytes, cumulus cells, and HMC-derived blastocysts revealed lesser transcript abundances in various resveratrol-treated groups., however no change in the same was observed for antiapoptotic gene (Bcl2). Differential expression of genes associated with developmental competence and nuclear reprogramming was also observed in HMC-derived blastocysts.

CONCLUSION

Our results show that resveratrol treatment at optimum concentrations (0.25 and 0.5 μM) during IVM produced beneficial microenvironment within oocytes by increasing the intracellular GSH, decreasing ROS level and this in turn, stimulated embryonic development and regulated gene expression.

Comparative expression analysis of embryonic development-related genes at different stages of parthenogenetic and in vitro fertilized embryos in caprine

Aberrant gene expression occurs in parthenogenetic embryos due to abnormal epigenetic modifications in the genome that probably diminish viability and enhance developmental abnormalities in these embryos. In the present study, five developmentally important genes (HPRT1, Cx43, Sox2, Mest and IGF2R) were analysed at different stages in parthenotes (haploid and diploid) and compared with similar stages in in vitro fertilized (IVF) embryos. The results indicated that in haploid parthenotes expression of HPRT1 was upregulated (P < 0.05) only at the 2-4-cell stage whereas Cx43 expression was significantly (P < 0.05) downregulated in all stages as compared with the control. However, expression of this gene was upregulated (P < 0.05) in 2-4-cell and morula stages of diploid parthenotes. Expression of Sox2 was significantly (P < 0.05) downregulated in morula stage haploid parthenotes, whereas it was upregulated (P < 0.05) in 8-16-cell stage diploid embryos. The expression of Mest was upregulated (P < 0.05) at the 2-4-cell stage of both haploid and diploid parthenotes, whereas it was downregulated in 8-16-cell stage diploid embryos as compared with control. IGF2R expression was upregulated (P < 0.05) only in morula stage haploid and diploid parthenote as compared with control. These results indicate that parthenogenetic embryos showed aberrant gene expression of developmentally important genes such as HPRT1, Cx43, Sox2, Mest and IGF2R in comparison with IVF embryos, this finding may be one of the major reasons for the poor developmental competence of parthenogenetic embryos.

Effects of repetitive ionomycin treatment on in vitro development of bovine somatic cell nuclear transfer embryos

To artificially activate embryos in somatic cell nuclear transfer (SCNT), chemical treatment with ionomycin has been used to induce transient levels of Ca(2+) and initiate reprogramming of embryos. Ca(2+) oscillation occurs naturally several times after fertilization (several times with 15- to 30-min intervals). This indicates how essential additional Ca(2+) influx is for successful reprogramming of embryos. Hence, in this report, the experimental design was aimed at improving the developmental efficiency of cloned embryos by repetitive Ca(2+) transients rather than the commonly used ionomycin treatment (4 min). To determine optimal Ca(2+) inflow conditions, we performed three different repetitive ionomycin (10 µM) treatments in reconstructed embryos: Group 1 (4-min ionomycin treatment, once), Group 2 (30-sec treatment, 4 times, 15-min intervals) and Group 3 (1-min treatment, 4 times, 15-min intervals). Pronuclear formation rates were checked to assess the effects of repetitive ionomycin treatment on reprogramming of cloned embryos. Cleavage rates were investigated on day 2, and the formation rates of blastocysts (BLs) were examined on day 7 to demonstrate the positive effect of repeated ionomycin treatment. In Group 3, a significant increase in BL formation was observed [47/200 (23.50%), 44/197 (22.33%) and 69/195 (35.38%) in Groups 1, 2 and 3, respectively]. Culturing embryos with different ionomycin treatments caused no significant difference among the groups in terms of the total cell number of BLs (164.3, 158.5 and 145.1, respectively). Additionally, expression of the anti-apoptotic Bcl-2 gene and MnSOD increased significantly in Group 3, whereas the expression of the pro-apoptotic Bax decreased statistically. In conclusion, the present study demonstrated that repeated ionomycin treatment is an improved activation method that can increase the developmental competence of SCNT embryos by decreasing the incidence of apoptosis.

Efficiency of SCNT buffalo (Bubalus bubalis) embryos in different culture medium and analysis of mRNA expression of insulin-like growth factors during embryogenesis

Growth factors in culture media are known to affect the embryo production rates in in vitro production cultures. To improve the efficiency of somatic cell nuclear transfer (SCNT) derived embryos in Indian buffaloes (Bubalus bubalis), embryos were cultured in three different culture mediums viz. Group-A; TCM-199 + FBS, Group-B; TCM-199 + Poly vinyl alcohol (PVA) and Group-C; CR1aa + BSA. Embryo production rate and expression level of insulin-like growth factor genes (IGF-1, IGF-1R, IGF-2 and IGF-2R) were analysed in embryo culture. Cleavage and blastocyst production rates were 62.5% and 22.3% in Group-A, 53.8% and 13.0% in Group-B and 62.0% and 19.2% in Group-C respectively, whereas in in vitro fertilization (IVF) control cultured in TCM-199 plus 10% FBS, rates were 79.1% and 29.4%. Relative gene expression of SCNT embryos was compared with that in IVF control. IGF-1 and IGF-2 mRNA expression at blastocyst stage was up-regulated (p ≤ 0.05) in all culture groups, while IGF-1R and IGF-2R expression was down regulated (p ≤ 0.05) in Group-B and Group-C. In conclusion, the higher mRNA levels at certain stages in different culture conditions affected in vitro development of SCNT embryos. These results show that the transcript level of the insulin-like growth factor genes was significantly altered by in vitro culture condition. Culture medium TCM-199 with 10% FBS produced higher number of embryos and was able to co-op with gene expression of IVF control. Differences continue to be observed between SCNT cultured and IVF embryos, and until these differences are minimized, aberrations in SCNT embryonic development will continue to arise.

Nuclear-cytoplasmic incompatibility and inefficient development of pig-mouse cytoplasmic hybrid embryos

Inter-species somatic cell nuclear transfer (iSCNT) embryos usually fail to develop to the blastocyst stage and beyond due to incomplete reprogramming of donor cell. We evaluated whether using a karyoplast that would require less extensive reprogramming such as an embryonic blastomere or the meiotic spindle from metaphase II oocytes would provide additional insight into the development of iSCNT embryos. Our results showed that karyoplasts of embryonic or oocyte origin are no different from somatic cells; all iSCNT embryos, irrespective of karyoplast origin, were arrested during early development. We hypothesized that nuclear-cytoplasmic incompatibility could be another reason for failure of embryonic development from iSCNT. We used pig-mouse cytoplasmic hybrids as a model to address nuclear-cytoplasmic incompatibility in iSCNT embryos. Fertilized murine zygotes were reconstructed by fusing with porcine cytoplasts of varying cytoplasmic volumes (1/10 (small) and 1/5 (large) total volume of mouse zygote). The presence of pig cytoplasm significantly reduced the development of mouse zygotes to the blastocyst stage compared with control embryos at 120 h post-human chorionic gondotropin (41 vs 6 vs 94%, P<0.05; 1/10, 1/5, control respectively). While mitochondrial DNA copy numbers remained relatively unchanged, expression of several important genes namely Tfam, Polg, Polg2, Mfn2, Slc2a3 (Glut3), Slc2a1 (Glut1), Bcl2, Hspb1, Pou5f1 (Oct4), Nanog, Cdx2, Gata3, Tcfap2c, mt-Cox1 and mt-Cox2 was significantly reduced in cytoplasmic hybrids compared with control embryos. These results demonstrate that the presence of even a small amount of porcine cytoplasm is detrimental to murine embryo development and suggest that a range of factors are likely to contribute to the failure of inter-species nuclear transfer embryos.

DNA methylation analysis on satellite I region in blastocysts obtained from somatic cell cloned cattle

Many observations have been made on cloned embryos and on adult clones by somatic cell nuclear transfer (SCNT), but it is still unclear whether the progeny of cloned animals is presenting normal epigenetic status. Here, in order to accumulate the information for evaluating the normality of cloned cattle, we analyzed the DNA methylation status on satellite I region in blastocysts obtained from cloned cattle. Embryos were produced by artificial insemination (AI) to non-cloned or cloned dams using semen from non-cloned or cloned sires. After 7 days of AI, embryos at blastocyst stage were collected by uterine flushing. The DNA methylation levels in embryos obtained by using semen and/or oocytes from cloned cattle were similar to those in in vivo embryos from non-cloned cattle. In contrast, the DNA methylation levels in SCNT embryos were significantly higher (P < 0.01) than those in in vivo embryos from non-cloned and cloned cattle, approximately similar to those in somatic cells used as donor cells. Thus, this study provides useful information that epigenetic status may be normal in the progeny of cloned cattle, suggesting the normality of germline cells in cloned cattle.

Comparative potential of cultured skin fibroblast, cumulus, and granulosa cell to produce somatic cell nuclear transfer (SCNT) preimplantation embryos in buffaloes (Bubalus bubalis) in relation to gene expressions

To improve the efficiency of somatic cell nuclear transfer (SCNT)-derived embryos in buffaloes (Bubalus bubalis), skin fibroblast, cumulus, and granulosa cells were cultured up to the 15th passage and cloned embryos were produced from each cell type. At the 15th passage the cumulative population doublings (CPDs) in cumulus cells was higher (60.78) than skin fibroblast (57.12) and granulosa (56.05) cell lines. Gene expression of chromatin remodelling proteins, that is, HDAC1, DNMT1, DNMT3a, and DNMT3b, were comparable at all five passages (P-3, P-6, P-9, P-12, and P-15) groups in cumulus cells but different in skin fibroblast and granulosa cells. Cleavage and blastocyst production rate in cumulus (65.9 and 27.4%)-derived embryos was higher than skin fibroblast (63.8 and 24.3%) and granulosa (62.5 and 22.3%)-derived embryos. Expressions of HDAC1, DNMT1, and DNMT3a mRNA in cumulus-derived blastocysts were similar to IVF blastocysts (control), whereas skin fibroblast and granulosa-derived blastocysts expression was significantly different (p < or = 0.05). DNMT3b mRNA expression in all the three donor cell types and IVF control were similar. The expression pattern of these genes showed the effect of donor cell type with different epigenetic reprogramming capabilities for SCNT embryo production rate. Overall, results indicated that cumulus cells are the best nuclear donor for SCNT.

Changes in the expression of pluripotency-associated genes during preimplantation and peri-implantation stages in bovine cloned and in vitro produced embryos

In cattle, embryos elongate before implantation and after hatching. Changes in gene expression during this transition are not well studied. Especially important are variations in the expression of pluripotency-associated genes as a result of assisted reproductive biotechnologies, such as cloning and in vitro fertilization (IVF). We hypothesize that there will be a decline in the expression of key pluripotency-associated genes and an increase in the expression of IFN-tau in elongated embryos when compared with day-7 blastocysts. To test this we generated cloned and IVF bovine day-7 blastocyst and day-17 elongated embryos (day 0 = day of nucleus transfer or IVF). Gene expression in all embryos was assessed via RT-qPCR. OCT4 was overexpressed (p < 0.05) in the cloned blastocysts when compared with IVF. No differences in gene expression at this stage between cloned and IVF embryos were found for EOMES, NANOG and FGF4. At elongation EOMES, NANOG and FGF4 were upregulated in IVF embryos (p < 0.05). IFN-tau and OCT4 were expressed at similar levels. There were changes in the expression levels for all transcripts between blastogenesis and elongation. NANOG, IFN-tau and EOMES were overexpressed in all the elongated embryos (p < 0.05), FGF4 was underexpressed in both treatments. OCT4 dropped drastically in the cloned elongated embryos, but not in the IVF. Interestingly only adult donor cells (but not fetal) from which the cloned embryos originated also expressed high levels of OCT4. Our findings might help to understand the shift of gene expression during elongation and to identify key markers of embryonic development useful for embryo screening purposes.

Elongation and gene expression in bovine cloned embryos transferred to temporary recipients

Elongated embryos provide a unique source of information about trophoblastic differentiation, gene expression and maternal-embryonic interactions; however they are difficult and costly to obtain, especially elongated cloned embryos. One alternative is their production in heterologous temporary recipients such as sheep and goats. We aimed to produce elongated bovine cloned embryos using heterologous transfer to temporary recipients. Day-7 cloned cattle blastocysts were transferred to the uteri of ewes and goats and recovered as elongated structures at day 17. We evaluated elongation, length, presence of embryonic disc and expression of several important genes for embryonic development. We also produced homologous (cloned cattle embryos transferred into cattle uteri). Cloned bovine blastocysts were able to proceed with preimplantation development through elongation with high efficiency despite the species to which they were transferred. In qualitative and quantitative RT-PCR experiments we found differences in the pattern of gene expression among embryos recovered from different species. Sox2, Nanog and FGF-4 were markedly deregulated. No previous reports about the expression pattern of the studied genes had been published for elongated bovine cloned embryos produced in intermediate recipients, furthermore, the pattern of expression of Nanog, Oct4, Eomes, Cdx2, IFN-tau, Dicer, FGF-4 and Sox2 shown here are novel for elongated cloned bovine embryos created by hand-made cloning. Our data confirmed that sheep and goats can be used as temporary recipients. This model could serve as a basis for further research on gene expression and cellular changes during bovine peri-implantation development.