Molecular regulators of human blastocyst development and hatching: Their significance in implantation and pregnancy outcome

In humans, blastocyst hatching and implantation events are two sequential, critically linked and rate-limiting events for a prospective pregnancy. These events are regulated by embryo-endometrium derived molecular factors which include hormones, growth factors, cytokines, immune-modulators, cell adhesion molecules and proteases. Due to poor viability of blastocysts, they fail to hatch and implant, leading to a low 'Live Birth Rates', majorly contributing to infertility. Here, embryo-derived biomarkers analysis plays a key role to assess potential biological viability of blastocysts which are capable of implantation and prospective pregnancy. Thus far, embryo-derived biomarkers examined are mostly immune-modulators which are thought to be associated with blastocyst development-implantation and progression of pregnancy, leading to live births. There is an urgent need to develop a quantitative and a reliable non-invasive approach aiding embryo selection for elective single embryo transfer and to minimize recurrent pregnancy loss and multiple pregnancies. In this article, we provide a comprehensive review on our current knowledge and understanding of potential embryo-derived molecular regulators, that is, biomarkers, of development of human blastocysts, their hatching and implantation. We discuss their potential implications in the assessment of blastocyst implantation potential and pregnancy outcome in terms of live births in humans.

Soluble human leukocyte antigen-G is a potential embryo viability biomarker and a positive predictor of live-births in humans

PROBLEM

Human infertility affects 15-20% of reproductive-age couples and it is mitigated by assisted reproductive technology (ART) approaches. Poor biological viability of embryos contributes to implantation failure and live birth rate (LBR). This study is aimed to examine whether or not embryo-secreted soluble human leukocyte antigen-G (sHLA-G) is (i) associated with developing embryos and (ii) able to predict successful pregnancy outcome.

METHOD OF STUDY

A retrospective, multicentric study using 539 human embryo spent medium samples (E-SMs), analysed for sHLA-G levels by ELISA. Correlation analysis was performed on sHLA-G levels with developing embryonic stages, their quality scores and pregnancy outcome in terms of LBR.

RESULTS

Of 539 E-SMs analysed, 445 had detectable sHLA-G (83%) with levels varying within and across clinics and, between stages of embryonic development. Levels of sHLA-G (ng/mL) were significantly (P < .05) different in E-SMs of cleavage-stage embryos versus blastocysts. There was an insignificant correlation between the sHLA-G levels and morphology scores of embryos. But, sHLA-G levels showed a positive correlation with grades of blastocysts and importantly, its levels were significantly (P < .05) higher in live-birth vis-a-vis no-birth cases. Also, levels were higher in live-births out of blastocysts-ETs versus cleavage-stage-embryo transfers. Altered levels were observed with embryos, which resulted in miscarriages. Overall, a significant (P < .0001) association of sHLA-G with live births was observed.

CONCLUSION

Embryo-derived sHLA-G can be a valuable embryo viability, independent, biomarker, which can predict live-birth outcome and it could be useful as an adjunct to existing criteria for elective single embryo transfer.

P–258 Ubiquitin, in the human embryo secretome, is a biomarker for embryo viability: a potential predictor of live-births, post embryo transfer

Study question

Whether embryo-secreted ubiquitin could serve as a predictive biomarker for embryo development and viability for assessing pregnancy outcome?

Summary answer

Embryo-secreted ubiquitin concentrations showed positive correlations with (a) developing embryonic stages, (b) implantation rates, (iii) live-birth rates. Their altered levels were associated with miscarriages.

What is known already

Human infertility affects 15–20% couple and is mitigated by ART approaches. Poor biological-viability of in vitro developed embryos contributes to implantation failure and low birth rates(LBR). The current morphology-based embryo selection approach has shortcomings in identifying biologically-viable embryos capable of producing live-births. Earlier studies have identified ubiquitin as a biomarker for embryo developmental competence. However, there have been no studies on estimations of ubiquitin in embryo-spent medium samples (E-SMs) and their correlative analysis with embryo-quality score and pregnancy outcome. Hence, such studies are required to establish whether or not ubiquitin could be a biomarker predicting pregnancy outcome.

Study design, size, duration

This was a retrospective, multi-centric study performed between July 2018 and September 2020. A total of 574 E-SMs (from 574 individual embryos), from 325 infertile women, were analysed for ubiquitin levels. Frozen E-SMs post-thaw were subjected to sandwich ELISA (Mybiosource, USA). Correlation analysis was performed on ubiquitin levels with developing embryonic stages and their scores, implantation rates (IRs) and pregnancy outcomes in terms of LBR.

Participants/materials, setting, methods

We measured ubiquitin levels in E-SMs obtained from three embryonic stages i.e., cleavage-stage (2–10-cells; n = 182), morulae (n = 102) and blastocysts (n = 290). Ubiquitin concentrations among three developmental stages were compared and analysed using the Student’s t-test/ANOVA (P ≤ 0.05), followed by Tukey posthoc test. Levels of ubiquitin were correlated (using Pearson/Spearman analysis) with (a) developing embryonic stages, (b) embryo morphology, (c) IRs, and (d) pregnancy outcomes in terms of LBR.

Main results and the role of chance

Of 574 E-SMs analysed, 540 (94.07%) had detectable ubiquitin levels (pg/ml) and they varied in an increasing manner across developing embryonic stages and, across the three clinics. We observed a significantly different (p &lt; 0.0001) levels of ubiquitin in three sets of secretors i.e low (153.1 ± 5.4; n = 219), medium (498.9 ± 15.7) & high (1615 ± 46.5) secretors. Levels of ubiquitin among three developmental stages were significantly (p &lt; 0.05) different under FET, but not with fresh-ET categories. Ubiquitin levels were independent of cleavage-stage morphology score but showed a positive correlation with blastocyst grades. Also, we observed a significant (p &lt; 0.05) positive correlation of ubiquitin levels with implantation rates. Importantly, ubiquitin levels were higher in E-SMs of embryos which gave live-births vis-à-vis those with no-births. Moreover, altered levels (very high low) were associated with those embryos which resulted in miscarriages. This is the first report which measured ubiquitin in individual hE-SMs from three developing embryos and showed a development stage-wise positive correlations as well as a significant association (p &lt; 0.0001) of ubiquitin levels with implantation and live-birth rates.

Limitations, reasons for caution

Observed variations in levels of ubiquitin across clinics could be attributed to (i) oocyte/sperm donors’ variation and their infertility status (i) IVF-ET protocol differences. A large multi-centric cohort studies are required to establish the predictive value of ubiquitin for assessing embryo-viability and pregnancy outcome in term of live-births.

Wider implications of the findings: For the first time, our multi-centric study showed developmental stage-specific changes in ubiquitin levels. It could be a valuable biomarker of embryo-viability and to predict IR and live-births. Ubiquitin, as a biomarker, could be a valuable adjunct to currently practicing embryo score system for selecting transferable quality embryos.

Trial registration number

Not applicable

P–172 Data-independent acquisition-proteomics of human embryo-spent medium and identification of potential embryo biomarkers

Study question

Can human embryo-derived protein(s) serve as viability biomarkers to predict pregnancy outcome, post embryo transfer?

Summary answer

The human embryo-spent medium proteome, using data-independent acquisition (DIA) approach, could identify novel biomarkers for use in elective embryo transfer.

What is known already

Morphological assessment is used for elective embryo transfer. To improve IVF outcomes and to avoid multiple gestations, embryo-viability assessment is required toward single embryo transfer. Embryo proteomics could provide a non-invasive approach to assess embryo viability. With the advent of DIA mode proteomics, a robust proteome of E-SM could be determined.

Study design, size, duration

This was a retrospective study performed between May and December, 2020 using ten E-SMs obtained from ten individual transferable-quality embryos. Frozen E-SMs, following post-thaw, were subjected to LC-MS-MS analysis. Identified proteome profiles were being potentially correlated to embryo quality scores and pregnancy outcomes in terms of live births.

Participants/materials, setting, methods

The E-SMs were processed for proteomic analysis and subjected to reduction, alkylation and trypsin digestion. Trypsin digested samples were desalted followed by LC-MS/MS using DIA method. Obtained results were searched against human peptide spectral library using Skyline. Differentially expressed proteins were identified by MSStat. Individual peptide peak area under the curve was normalized and analyzed using Student t-test. Fold change was calculated to identify differentially regulated proteins in blank and E-SM samples.

Main results and the role of chance

Using a high-resolution mass spectrometer and high throughput DIA method, we identified 5,502 peptides corresponding to 3,396 proteins from blank and E-SM samples, derived from five non-transferred embryos. We observed that 516 proteins were specific to E-SMs vies-a-vies those of embryo-free blank medium. Statistical analysis showed that 25 proteins were significantly present E-SMs vs. blank. Interestingly, we observed that 16 proteins were down regulated and 9 were up regulated in E-SMs vs. blank medium. Furthermore, E-SMs, from transferred embryos, contained 2,467 peptides corresponding to 1,741 proteins; of these, 1, 689 proteins were specific to E-SMs with 60 (58 down regulated and 2 up regulated) of them being significantly expressed in E-SMs vis-à-vis embryo-free blank medium. Considering the available met analysis published data, our study is the first to use DIA acquisition for high-throughput analysis of human embryo proteome and identification of biomarkers of embryo viability and for possible prediction of pregnancy outcome.

Limitations, reasons for caution

Proteins, other than HAS, detected in the blank medium could be because of non-purified HAS or undeclared proteins and DIA approach used. A large cohort study and meta-analysis using DIA mode are required to establish the embryo-proteome having predictive potential for embryo biological viability.

Wider implications of the findings: For the first time, using DIA mode, a global embryo proteome assessment could be made, establishing a novel embryo viability biomarkers. This, along with the morphological analysis, could be practiced for selection of transferable quality embryo(s)

Trial registration number

Not applicable

Adenosine deaminase modulates metabolic remodeling and orchestrates joint destruction in rheumatoid arthritis

Rheumatoid Arthritis (RA) is a chronic autoimmune disease associated with inflammation and joint remodeling. Adenosine deaminase (ADA), a risk factor in RA, degrades adenosine, an anti-inflammatory molecule, resulting in an inflammatory bias. We present an integrative analysis of clinical data, cytokines, serum metabolomics in RA patients and mechanistic studies on ADA-mediated effects on in vitro cell culture models. ADA activity differentiated patients into low and high ADA sets. The levels of the cytokines TNFα, IFNγ, IL-10, TGFβ and sRANKL were elevated in RA and more pronounced in high ADA sets. Serum metabolomic analysis shows altered metabolic pathways in RA which were distinct between low and high ADA sets. Comparative analysis with previous studies shows similar pathways are modulated by DMARDs and biologics. Random forest analysis distinguished RA from control by methyl-histidine and hydroxyisocaproic acid, while hexose-phosphate and fructose-6-phosphate distinguished high ADA from low ADA. The deregulated metabolic pathways of High ADA datasets significantly overlapped with high ADA expressing PBMCs GEO transcriptomics dataset. ADA induced the death of chondrocytes, synoviocyte proliferation, both inflammation in macrophages and their differentiation into osteoclasts and impaired differentiation of mesenchymal stem cells to osteoblasts and mineralization. PBMCs expressing elevated ADA had increased expression of cytokines and P2 receptors compared to synovial macrophages which has low expression of ADA. Our data demonstrates increased cytokine levels and distinct metabolic signatures of RA based on the ADA activity, suggests an important role for ADA in the pathophysiology of RA joints and as a potential marker and therapeutic target in RA patients.

Research on early mammalian development in India

Historically, research in India on early mammalian development had only begun, rather modestly, in the last century, unlike the USA and UK. In India, initial studies were on gonadal and reproductive tissue development and function and they were limited to anatomical and histological characterization. This was followed by research on fertility regulation and contraception. Since the 1960s, a major initiative took place regarding endocrine biochemistry and the use of antifertility agents in inhibiting gonadal function and early development. Post-independence, the Indian government´s funding support enabled universities and institutions to embark on various research disciplines in biology but with no particular emphasis on developmental biology per se. Subsequently, India made significant progress in the area of mammalian reproduction and development, but not specifically in the core aspects of developmental biology. Reasons for this could be due to the nation's compulsion to invest and embark on socio-economic and infrastructure development and on research involving family planning methods for reversible-affordable contraceptives to curtail population growth. With regard to the latter, biologists were involved in hormone-based contraception research. During this pursuit, insights were achieved into basic aspects of the development of gonads, gametes and embryos. Notwithstanding this, in the post-1980s through to the present time, Indian scientists have contributed to (i) the understanding of the cellular and molecular regulation of early development, (ii) developing genetically modified mouse models, (iii) using assisted reproductive technologies, generating mammalian progeny, including humans and (iv) deriving pluripotent stem cell lines for developmental studies. This article provides a perspective on the past and current status of early mammalian development research in India.

Expression and function of interleukin-1β is required for hamster blastocyst hatching: Involvement of hatching-associated cathepsin proteases

In mammals, the phenomenon of blastocyst hatching is an essential prerequisite for successful implantation. Blastocyst hatching is regulated by various molecules. Of them, cytokines, expressed by preimplantation embryos, are thought to be functionally important in blastocyst development and hatching, but their mechanistic roles are not clearly understood. Here, we examined the involvement of two cytokines, namely, interleukin-1β (IL-1β) and its natural antagonist, IL-1ra, in blastocyst hatching in the golden hamster. Blastocysts expressed both cytokines and their receptor, IL-1rt1. Supplementation of IL-1β to cultured eight-cell embryos improved blastocyst hatching (84.1% ± 4.2% vs. 66.6% ± 6.8%; treated vs. control). This improvement was diminished by IL-1ra treatment (23.6% ± 12.9% vs. 76.4% ± 12.9%; treated vs. control). Interestingly, IL-1β-treated embryos showed increased messenger RNA expression of zonalytic proteases, that is, cathepsin-L and -B by 1.9 ± 0.5- and 3.5 ± 0.1-folds, respectively. This was accompanied by their increased enzyme activities; cathepsin-L by 2.8 ± 0.7 fold and -B by 2.3 ± 0.7-fold. Strikingly, proteases and IL-1β were intensely colocalized to trophectodermal projections of hatching blastocysts. This is the first report to show the involvement of embryonic IL-1β in regulating hatching-associated proteases required for blastocyst hatching.

Expression of IL-1β and implantation serine proteases is required for mouse blastocyst hatching

Mammalian blastocyst hatching is a critically indispensable process for successful implantation. One of the major challenges in IVF clinics is to achieve superior embryonic development with intrinsically potent hatching-competent blastocyst. However, the molecular regulation of hatching phenomenon is poorly understood. In this study, we examined the expression and function of one of the cytokines, IL-1β during blastocyst hatching in the mouse. In particular, the expression of IL-1β (Interleukin-1β), IL-1ra (Interleukin-1 receptor antagonist) and their functional receptor IL-1rt1 (Interleukin 1 receptor type-1) in morulae, zona intact- and hatched-blastocysts was studied. Supplementation of IL-1β to cultured embryos accelerated blastocyst development with improved hatching (treated: 89.6 ± 3.6% vs untreated: 65.4 ± 4.1%). When embryos were treated with IL-1ra, blastocyst hatching was decreased (treated: 28.8 ± 3.1% vs untreated: 67.5 ± 3.8%). Moreover, IL-1β and IL-1ra influenced the expression of hatching enzymes viz., implantation serine proteases (ISP1 and ISP2). While IL-1β increased the embryonic mRNA expression of ISPs (Isp1: 2-4; Isp2: 9- to 11-fold), IL-1ra decreased expression. The protein localization studies revealed increased nuclear presence predominantly of ISP 2 in IL-1β-treated blastocysts. This is the first report to show the functional significance of embryonic IL-1β in regulating hatching-associated proteases, particularly ISP2. These findings have implications in our understanding of molecular regulation of blastocyst hatching and implantation failure in other species including humans.

In situ differentiation of human-induced pluripotent stem cells into functional cardiomyocytes on a coaxial PCL-gelatin nanofibrous scaffold

Human-induced pluripotent stem cells (hiPSCs) derived cardiomyocytes (hiPSC-CMs) have been explored for cardiac regeneration and repair as well as for the development of in vitro 3D cardiac tissue models. Existing protocols for cardiac differentiation of hiPSCs utilize a 2D culture system. However, the efficiency of hiPSC differentiation to cardiomyocytes in 3D culture systems has not been extensively explored. In the present study, we investigated the efficiency of cardiac differentiation of hiPSCs to functional cardiomyocytes on 3D nanofibrous scaffolds. Coaxial polycaprolactone (PCL)-gelatin fibrous scaffolds were fabricated by electrospinning and characterized using scanning electron microscopy (SEM) and fourier transform infrared (FTIR) spectroscopy. hiPSCs were cultured and differentiated into functional cardiomyocytes on the nanofibrous scaffold and compared with 2D cultures. To assess the relative efficiencies of both the systems, SEM, immunofluorescence staining and gene expression analyses were performed. Contractions of differentiated cardiomyocytes were observed in 2D cultures after 2 weeks and in 3D cultures after 4 weeks. SEM analysis showed no significant differences in the morphology of cells differentiated on 2D versus 3D cultures. However, gene expression data showed significantly increased expression of cardiac progenitor genes (ISL-1, SIRPA) in 3D cultures and cardiomyocytes markers (TNNT, MHC6) in 2D cultures. In contrast, immunofluorescence staining showed no substantial differences in the expression of NKX-2.5 and α-sarcomeric actinin. Furthermore, uniform migration and distribution of the in situ differentiated cardiomyocytes was observed in the 3D fibrous scaffold. Overall, our study demonstrates that coaxial PCL-gelatin nanofibrous scaffolds can be used as a 3D culture platform for efficient differentiation of hiPSCs to functional cardiomyocytes.

Systems analysis of avascular necrosis of femoral head using integrative data analysis and literature mining delineates pathways associated with disease

Avascular necrosis of femoral head (AVNFH) is a debilitating disease, which affects the middle aged population. Though the disease is managed using bisphosphonate, it eventually leads to total hip replacement due to collapse of femoral head. Studies regarding the association of single nucleotide polymorphisms with AVNFH, transcriptomics, proteomics, metabolomics, biophysical, ultrastructural and histopathology have been carried out. Functional validation of SNPs was carried out using literature. An integrated systems analysis using the available datasets might help to gain further insights into the disease process. We have carried out an analysis of transcriptomic data from GEO-database, SNPs associated with AVNFH, proteomic and metabolomic data collected from literature. Based on deficiency of vitamins in AVNFH, an enzyme-cofactor network was generated. The datasets are analyzed using ClueGO and the genes are binned into pathways. Metabolomic datasets are analyzed using MetaboAnalyst. Centrality analysis using CytoNCA on the data sets showed cystathionine beta synthase and methylmalonyl-CoA-mutase to be common to 3 out of 4 datasets. Further, the genes common to at least two data sets were analyzed using DisGeNET, which showed their involvement with various diseases, most of which were risk factors associated with AVNFH. Our analysis shows elevated homocysteine, hypoxia, coagulation, Osteoclast differentiation and endochondral ossification as the major pathways associated with disease which correlated with histopathology, IHC, MRI, Micro-Raman spectroscopy etc. The analysis shows AVNFH to be a multi-systemic disease and provides molecular signatures that are characteristic to the disease process.

Successful Derivation of an Induced Pluripotent Stem Cell Line from a Genetically Nonpermissive Enhanced Green Fluorescent Protein-Transgenic FVB/N Mouse Strain

The embryonic stem cell line derivation from nonpermissive mouse strains is a challenging and highly inefficient process. The cellular reprogramming strategy provides an alternative route for generating pluripotent stem cell (PSC) lines from such strains. In this study, we successfully derived an enhanced green fluorescent protein (EGFP)-transgenic "N9" induced pluripotent stem cell (iPS cell, iPSC) line from the FVB/N strain-derived mouse embryonic fibroblasts (MEFs). The exposure of MEFs to human OCT4, SOX2, KLF4, and c-MYC (OSKM) transgenes via lentiviral transduction resulted in complete reprogramming. The N9 iPS cell line demonstrated all the criteria of a typical mouse PSC line, including normal colony morphology and karyotype (40,XY), high replication and propagation efficiencies, expression of the pluripotency-associated genes, spontaneous differentiation to three germ lineage-derived cell types, and robust potential of chimeric blastocyst formation. Taken together, using human OSKM genes for transduction, we report, for the first time, the successful derivation of an EGFP-expressing iPS cell line from a genetically nonpermissive transgenic FVB/N mouse. This cell line could provide opportunities for designing protocols for efficient derivation of PSC lines from other nonpermissive strains and developing mouse models of human diseases.

Mouse embryonic stem cell-derived cardiomyocytes cease to beat following exposure to monochromatic light: association with increased ROS and loss of calcium transients

We earlier established the mouse embryonic stem (ES) cell "GS-2" line expressing enhanced green fluorescent protein (EGFP) and have been routinely using it to understand the molecular regulation of differentiation into cardiomyocytes. During such studies, we made a serendipitous discovery that functional cardiomyocytes derived from ES cells stopped beating when exposed to blue light. We observed a gradual cessation of contractility within a few minutes, regardless of wavelength (nm) ranges tested: blue (~420-495), green (~510-575), and red (~600-700), with green light manifesting the strongest impact. Following shifting of cultures back into the incubator (darkness), cardiac clusters regained beatings within a few hours. The observed light-induced contractility-inhibition effect was intrinsic to cardiomyocytes and not due to interference from other cell types. Also, this was not influenced by any physicochemical parameters or intracellular EGFP expression. Interestingly, the light-induced cardiomyocyte contractility inhibition was accompanied by increased intracellular reactive oxygen species (ROS), which could be abolished in the presence of N-acetylcysteine (ROS quencher). Besides, the increased intracardiomyocyte ROS levels were incidental to the inhibition of calcium transients and suppression of mitochondrial activity, both being essential for sarcomere function. To the best of our knowledge, ours is the first report to demonstrate the monochromatic light-mediated inhibition of contractions of cardiomyocytes with no apparent loss of cell viability and contractility. Our findings have implications in cardiac cell biology context in terms of 1) mechanistic insights into light impact on cardiomyocyte contraction, 2) potential use in laser beam-guided (cardiac) microsurgery, photo-optics-dependent medical diagnostics, 3) transient cessation of hearts during coronary artery bypass grafting, and 4) functional preservation of hearts for transplantation.

Influence of the number of calves and lactating adult females in a herd on the adrenocortical activity of free-ranging Asian elephants

Abstract ContextPhysiological stress has the potential to influence animal population persistence. The endangered Asian elephant (Elephas maximus) is involved in intense conflict with humans in many parts of its range, which likely leads to stress for individuals and groups, with consequences for population survival. Thus, it is important to understand how the elephants’ stress levels are influenced by socio-ecological factors when not directly exposed to human-induced threats, and to use this understanding to improve conservation and management strategies. AimsThe present study was designed to provide baseline information on the link between socio-ecological factors and stress levels of undisturbed populations of elephants. The main aim was to determine the influence of a number of factors – herd size, season, number of calves and adult females present in a herd and their lactational status and body condition – on the adrenocortical activity of free-ranging adult female Asian elephants living in protected forests (without any direct exposure to human-induced threats), by measuring their faecal glucocorticoid metabolite (fGCM) levels. MethodsA total of 145 fresh faecal samples were collected from 123 identified adult female elephants inhabiting Bandipur and Nagarahole National Parks of southern India, between the years 2013 and 2015. fGCM levels were measured by employing a group-specific standardised 11-oxoetiocholanolone enzyme immunoassay (EIA). A generalised linear mixed-effects model (GLMM) was used to assess the influence of socio-ecological factors on fGCM levels of adult female elephants. Key resultsWhen fGCM levels were analysed with a GLMM, the following patterns were observed: fGCM levels were negatively correlated with the number of adult females (herd size) and positively correlated with the number of calves in a herd and active lactational status of an adult female. fGCM levels of adult female elephants were higher during the dry season (February to May) than wet season (August to December) and negatively correlated with body condition scores. ConclusionsAdrenocortical activity of female elephants is significantly influenced by the number of calves and adult females present in the herd, seasonality and lactational status. ImplicationsIt is important to consider the influence of multiple ecological and social correlates when assessing and interpreting the adrenocortical activity of Asian elephants. Our findings highlight the importance of maintaining the social structure of elephants in the wild to avoid detrimental effects on their physiological health. Insights from such assessments could be used to evaluate the stress in elephants that are involved in direct conflicts with humans to take appropriate management decisions for mitigating conflicts.

Directed differentiation of mouse P19 embryonal carcinoma cells to neural cells in a serum- and retinoic acid-free culture medium

P19 embryonal carcinoma cells (EC-cells) provide a simple and robust culture system for studying neural development. Most protocols developed so far for directing neural differentiation of P19 cells depend on the use of culture medium supplemented with retinoic acid (RA) and serum, which has an undefined composition. Hence, such protocols are not suitable for many molecular studies. In this study, we achieved neural differentiation of P19 cells in a serum- and RA-free culture medium by employing the knockout serum replacement (KSR) supplement. In the KSR-containing medium, P19 cells underwent predominant differentiation into neural lineage and by day 12 of culture, neural cells were present in 100% of P19-derived embryoid bodies (EBs). This was consistently accompanied by the increased expression of various neural lineage-associated markers during the course of differentiation. P19-derived neural cells comprised of NES⁺ neural progenitors (~ 46%), TUBB3⁺ immature neurons (~ 6%), MAP2⁺ mature neurons (~ 2%), and GFAP⁺ astrocytes (~ 50%). A heterogeneous neuronal population consisting of glutamatergic, GABAergic, serotonergic, and dopaminergic neurons was generated. Taken together, our study shows that the KSR medium is suitable for the differentiation of P19 cells to neural lineage without requiring additional (serum and RA) supplements. This stem cell differentiation system could be utilized for gaining mechanistic insights into neural differentiation and for identifying potential neuroactive compounds.

Assessment of ovarian follicular dynamics and folliculogenesis associated endocrine profiles following gonadotropin stimulation in the bonnet monkey

We evaluated ovarian follicular dynamics in bonnet monkeys by employing trans-abdominal ultrasonography. Following the administration of human follicle stimulating hormone (hFSH) and/or human menopausal gonadotropin (hMG), multiple follicular development was assessed and their numbers, size and growth profiles were monitored. The ultrasonograms showed that the follicular antrum appeared distinctly anechoic with well-defined hyperechoic borders. Depending on the type, quantity (12.5-25IU), and duration (6-9days) of hormones administered, the number of developing follicles was 2-12 per ovary with their lowest diameter being 2mm. With continued hormone administration, their numbers and diameters increased; which were more pronounced in animals administered with hFSH than with hMG, with follicles of 6-8mm. Interestingly, human chorionic gonadotropin (hCG) injection (2000-3000IU), when follicles acquiring >6-8mm sizes, induced the maximum expansion of antral follicles with sizes reaching up to 14mm. On days 3-5 post-hCG, the ultrasonograms showed loosely demarcated multiple hypoechoic structures and well-demarcated hyperechoic structures with anechoic/hypoechoic cores corresponding to unruptured luteinized follicles and corpora lutea, respectively. On day 4 post-hCG, there was a substantial reduction in the number of antral follicles. In stimulated animals, follicular growth, ovulation, and formation of luteal structures were accompanied by corresponding physiological changes in the serum estradiol and progesterone profiles. These findings, for the first time, showed that ultrasonographic imaging approach is useful for precise monitoring of temporal changes in follicular developmental dynamics and to time the hCG induced ovulation in the bonnet monkey.

Efficient neural differentiation of mouse pluripotent stem cells in a serum-free medium and development of a novel strategy for enrichment of neural cells

Pluripotent stem cells (PSCs) offer an excellent model to study neural development and function. Although various protocols have been developed to direct the differentiation of PSCs into desired neural cell types, many of them suffer from limitations including low efficiency, long duration of culture, and the use of expensive, labile, and undefined growth supplements. In this study, we achieved efficient differentiation of mouse PSCs to neural lineage, in the absence of exogenous molecules, by employing a serum-free culture medium containing knockout serum replacement (KSR). Embryoid bodies (EBs) cultured in this medium predominantly produced neural cells which included neural progenitors (15-18%), immature neurons (8-24%), mature neurons (10-26%), astrocytes (27-61%), and oligodendrocytes (∼1%). Different neuronal subtypes including glutamatergic, GABAergic, cholinergic, serotonergic, and dopaminergic neurons were generated. Importantly, neurons generated in the KSR medium were electrically active. Further, the EB scooping strategy, involving the removal of the EB core region from the peripheral EB outgrowth, resulted in the enrichment of PSC-derived neural cells. Taken together, this study provides the evidence that the KSR medium is ideal for the rapid and efficient generation of neural cells, including functional neurons, from PSCs without the requirement of any other additional molecule.

Assessment of season-dependent body condition scores in relation to faecal glucocorticoid metabolites in free-ranging Asian elephants

We studied seasonal and annual changes in visual body condition scores (BCSs), and assessed how these scores were related to levels of faecal glucocorticoid metabolites (fGCMs) in free-ranging Asian elephants (Elephas maximus) in the seasonally dry tropical forests of the Mysore and Nilgiri Elephant Reserves in southern India. We assessed the animals' BCS visually on a scale of 1 to 5; where 1 represents a very thin and 5 represents a very fat elephant. To understand the influence of seasonality on BCS, we sampled the population during dry (n = 398) and wet seasons (n = 255) of 2013 and 2015 while, for annual changes in BCS, we sampled nine free-ranging adult females from different family groups that had been repeatedly sighted over seven years. To evaluate the influence of body condition on fGCM, 307 faecal samples were collected from 261 different elephants and were analysed. As a parameter of adrenocortical activity, and thus stress, fGCM was measured (μg/g) in the ethanol-extracted samples using a group-specific 11-oxoaetiocholanolone EIA (antibody raised against 11-oxoaetiocholanolone-17-CMO:BSA and biotinylated-11-oxoaetiocholanolone as a label). Effect of age and season on BCS in relation to fGCM was also studied. A seasonal shift in BCS was observed as expected, i.e. individuals with low BCS were more frequent during the dry season when compared with the wet season. Concentrations of fGCM were highest in individuals with lowest BCS (BCS 1) and then significantly declined till BCS 3. fGCM levels were almost comparable for BCS 3, 4 and 5. This pattern was more conspicuous in female than in male elephants. Season-dependent BCS, hence, reflect the stress status as measured by fGCM, especially in female Asian elephants. This could be used as an important non-invasive approach to monitor the physiological health of free-ranging elephant populations.

Ascorbic acid-mediated enhanced cardiomyocyte differentiation of mouse ES-cells involves interplay of DNA methylation and multiple-signals

Embryonic stem cells (ES-cells) provide a good model system to study lineage-specific differentiation. Though, the differentiation of ES-cells to cardiomyocytes is documented, a clear understanding of the molecular mechanism of differentiation and improved functional-differentiation efficiency are yet to be achieved. In this regard, ascorbic acid (Aa) is shown to be one of the effective cardiac inducers in ES-cells. But, its mechanism is poorly understood. We therefore, investigated the mechanism of Aa-mediated cardiomyocyte differentiation of ES-cells. Here, we describe the potential involvement of epigenetic (DNA methylation) as well as integrin- and Erk- signaling systems during cardiomyocyte differentiation. Transgenic GS-2 ES-cells and wild-type D3 ES-cells were differentiated to cardiomyocytes, in the presence or absence of Aa and with or without inhibitors of Erk-, collagen- and integrin- pathways. At specific time points, differentiated states of ES-cells were scored by gene expression analyses and the proportion of functional cTnI⁺ cardiomyocytes. DNA methylation changes of Isl-1, BMP-2, GATA-4 and α-MHC in cardiogenic cells, following stimulation with Aa, were analyzed by using methylation specific PCR (MSP). We observed that Aa, when applied in initial phase of ES-cell differentiation, consistently enhanced cardiac differentiation (99%) over that observed during spontaneous differentiation (70%). This was associated with enhanced expressions of cardiogenesis-associated genes. A two-fold increase in cTnI⁺ cells was observed, with appropriate myofibril arrangement. The observed effect of Aa was due to enhanced collagen and integrin signaling, coupled with a high p-ERK1/2 expression, downstream. Besides, the involvement of DNA methylation in regulating the expression of cardiac genes i.e., Isl-1 and α-MHC was also observed. Overall, this study, for the first time, demonstrates that Aa-mediated cardiac enhancement is brought about, mechanistically, through the interplay of epigenetic changes in DNA methylation of cardiac genes (Isl-1 and α-MHC) and integrin signaling system.

Cytokines and Blastocyst Hatching

Blastocyst implantation into the uterine endometrium establishes early pregnancy. This event is regulated by blastocyst- and/or endometrium-derived molecular factors which include hormones, growth factors, cell adhesion molecules, cytokines and proteases. Their coordinated expression and function are critical for a viable pregnancy. A rate-limiting event that immediately precedes implantation is the hatching of blastocyst. Ironically, blastocyst hatching is tacitly linked to peri-implantation events, although it is a distinct developmental phenomenon. The exact molecular network regulating hatching is still unclear. A number of implantation-associated molecular factors are expressed in the pre-implanting blastocyst. Among others, cytokines, expressed by peri-implantation blastocysts, are thought to be important for hatching, making blastocysts implantation competent. Pro-inflammatory (IL-6, LIF, GM-CSF) and anti-inflammatory (IL-11, CSF-1) cytokines improve hatching rates; they modulate proteases (MMPs, tPAs, cathepsins and ISP1). However, functional involvement of cytokines and their specific mediation of hatching-associated proteases are unclear. There is a need to understand mechanistic roles of cytokines and proteases in blastocyst hatching. This review will assess the available knowledge on blastocyst-derived pro-inflammatory and anti-inflammatory cytokines and their role in potentially regulating blastocyst hatching. They have implications in our understanding of early embryonic loss and infertility in mammals, including humans.

Differential expression of estrogen receptor alpha in the embryonic adrenal-kidney-gonadal complex of the oviparous lizard, Calotes versicolor (Daud.)

Estrogen signalling is critical for ovarian differentiation in reptiles with temperature-dependent sex determination (TSD). To elucidate the involvement of estrogen in this process, adrenal-kidney-gonadal (AKG) expression of estrogen receptor (ERα) was studied at female-producing temperature (FPT) in the developing embryos of the lizard, Calotes versicolor which exhibits a distinct pattern of TSD. The eggs of this lizard were incubated at 31.5±0.5°C (100% FPT). The torso of embryos containing adrenal-kidney-gonadal complex (AKG) was collected during different stages of development and subjected to Western blotting and immunohistochemistry analysis. The ERα antibody recognized two protein bands with apparent molecular weight ∼55 and ∼45kDa in the total protein extracts of embryonic AKG complex of C. versicolor. The observed results suggest the occurrence of isoforms of ERα. The differential expression of two different protein isoforms may reveal their distinct role in cell proliferation during gonadal differentiation. This is the first report to reveal two isoforms of the ERα in a reptile during development. Immunohistochemical studies reveal a weak, but specific, cytoplasmic ERα immunostaining exclusively in the AKG during late thermo-sensitive period suggesting the responsiveness of AKG to estrogens before gonadal differentiation at FPT. Further, cytoplasmic as well as nuclear expression of ERα in the medulla and in oogonia of the cortex (faint activity) at gonadal differentiation stage suggests that the onset of gonadal estrogen activity coincides with sexual differentiation of gonad. Intensity and pattern of the immunoreactions of ERα in the medullary region at FPT suggest endogenous production of estrogen which may act in a paracrine fashion to induce neighboring cells into ovarian differentiation pathway.

Endocrine correlates of musth in free-ranging Asian elephants (Elephas maximus) determined by non-invasive faecal steroid hormone metabolite measurements

The occurrence of musth, a period of elevated levels of androgens and heightened sexual activity, has been well documented for the male Asian elephant (Elephas maximus). However, the relationship between androgen-dependent musth and adrenocortical function in this species is unclear. The current study is the first assessment of testicular and adrenocortical function in free-ranging male Asian elephants by measuring levels of testosterone (androgen) and cortisol (glucocorticoid – a physiological indicator of stress) metabolites in faeces. During musth, males expectedly showed significant elevation in faecal testosterone metabolite levels. Interestingly, glucocorticoid metabolite concentrations remained unchanged between musth and non-musth periods. This observation is contrary to that observed with wild and captive African elephant bulls and captive Asian bull elephants. Our results show that musth may not necessarily represent a stressful condition in free-ranging male Asian elephants.

Expression and function of cyclooxygenase-2 is necessary for hamster blastocyst hatching

Blastocyst hatching is critical for successful implantation leading to pregnancy. Its failure causes infertility. The phenomenon of blastocyst hatching in humans is poorly understood and the available information on this stems from studies of rodents such as mice and hamsters. We and others showed that hamster blastocyst hatching is characterized by firstly blastocyst deflation followed by a dissolution of the zona pellucida (zona) and accompanied by trophectodermal projections (TEPs). We also showed that embryo-derived cathepsins (Cat) proteases, specifically Cat-L, -B and -P act as zonalysins and are responsible for hatching. In this study, we show the expression and function of one of the potential regulators of embryogenesis, cyclooxygenase (COX)-2 during blastocyst development and hatching. The expression of COX-2 mRNA and protein was observed in 8-cell through hatched blastocyst stages and it was also localized to blastocyst's TEPs. Specific COX-2 inhibitors, NS-398 and CAY-10404, inhibited blastocyst hatching; percentages achieved were only 28.4 ± 5.3 and 32.3 ± 5.4%, respectively, compared with >90% with untreated embryos. Interestingly, inhibitor-treated blastocysts failed to deflate, normally observed during hatching. Supplementation of prostaglandins (PGs)-E2 or -I2 to cultured embryos reversed the inhibitors' effect on hatching and also the deflation behavior. Importantly, the levels of mRNA and protein of Cat-L, -B and -P showed a significant reduction in the inhibitor-treated embryos compared with untreated embryos, although its mechanism remains to be examined. These data provide the first evidence that COX-2 is critical for blastocyst hatching in the golden hamster.

Aza-induced cardiomyocyte differentiation of P19 EC-cells by epigenetic co-regulation and ERK signaling

Stem cells in cell based therapy for cardiac injury is being potentially considered. However, genetic regulatory networks involved in cardiac differentiation are not clearly understood. Among stem cell differentiation models, mouse P19 embryonic carcinoma (EC) cells, are employed for studying (epi)genetic regulation of cardiomyocyte differentiation. Here, we comprehensively assessed cardiogenic differentiation potential of 5-azacytidine (Aza) on P19 EC-cells, associated gene expression profiles and the changes in DNA methylation, histone acetylation and activated-ERK signaling status during differentiation. Initial exposure of Aza to cultured EC-cells leads to an efficient (55%) differentiation to cardiomyocyte-rich embryoid bodies with a threefold (16.8%) increase in the cTnI+ cardiomyocytes. Expression levels of cardiac-specific gene markers i.e., Isl-1, BMP-2, GATA-4, and α-MHC were up-regulated following Aza induction, accompanied by differential changes in their methylation status particularly that of BMP-2 and α-MHC. Additionally, increases in the levels of acetylated-H3 and pERK were observed during Aza-induced cardiac differentiation. These studies demonstrate that Aza is a potent cardiac inducer when treated during the initial phase of differentiation of mouse P19 EC-cells and its effect is brought about epigenetically and co-ordinatedly by hypo-methylation and histone acetylation-mediated hyper-expression of cardiogenesis-associated genes and involving activation of ERK signaling.

Successful derivation of EGFP-transgenic embryonic stem cell line from a genetically non-permissive FVB/N mouse

Derivation of embryonic stem (ES)-cell lines from genetically non-permissive mouse strains, such as FVB/N, has been difficult, despite this strain offering advantages for mouse transgenesis for developmental studies. We earlier generated β-actin promoter-driven enhanced green fluorescent protein (EGFP)-transgenic FVB/N mice, expressing EGFP in all cells. Here, by optimizing culture system and using RESGROTM ES-cell culture medium, we successfully derived EGFP-transgenic ES-cell line, 'GS-2' line, from F1 hybrid blastocysts, from wild-type 129/SvJ female X EGFP-transgenic homozygous FVB/N male. The GS-2 ES-cell line exhibited all defining criteria of a typical ES-cell line, including normal colony morphology and karyotype (40,XY), high replication-expansion efficiency (passages: >100), expression of pluripotent markers (Oct-4, Nanog, Sox-2, SSEA-1 and others) and, embryoid body (EB) development and EB differentiation to ecto-/meso-/endo-dermal cell types, expressing nestin, BMP-4 and α-fetoprotein, respectively. GS-2 ES-cells formed (i) teratoma containing three germ lineage-derived cell types, (ii) chimeric blastocysts and fetuses, following their aggregation with wild-type 8-cell embryos, (iii) functional cardiac clusters and (iv) predominantly neural cell types when EBs were developed in KOSR-supplemented medium. Taken together, we derived a robust EGFP-transgenic GS-2 ES-cell line, from a non-permissive transgenic (FVB/N) mouse by a single cross to 129/SvJ wild-type mouse. The GS-2 ES-cell line exhibited full differentiation potential, in vitro/in vivo, providing enormous opportunity for stem cell research, including experimental cell transplantation studies.

Assessment of estrus cyclicity in the Asian elephant (Elephas maximus) by measurement of fecal progesterone metabolite 5α-P-3OH, using a non-invasive assay

Reproductive management of the Asian elephant (Elephas maximus) is important for its conservation. To monitor its estrous cyclicity, we earlier used an indirect ELISA to show that levels of fecal progesterone (P(4))-metabolite (allopregnanolone: 5α-P-3OH) in semi-captive females sampled randomly positively correlated with serum P(4) levels [12]. In this longitudinal study (51 weeks), we measured levels of fecal 5α-P-3OH and serum P(4) in seven semi-captive female elephants. Females exhibited three types of hormonal profiles. Four females showed cyclical patterns of fecal 5α-P-3OH and serum P(4) typical of normal estrous cycles, two showed acyclic pattern while one showed high values indicative of a pregnant animal. Values for anestrous or follicular phases were ≤ 0.3 μg g(-1) (5α-P-3OH) and ≤ 0.3 ng mL(-1) (P(4)); for luteal phase 0.32-11.09 μg g(-1) (5α-P-3OH) and 0.32-1.48 ng mL(-1) (P(4)); for pregnancy 1.41-7.38 μg g(-1) (5α-P-3OH) and 0.39-1.6 ng mL(-1) (P(4)). A positive correlation (t = 8.8, p < 0.01, n = 321) between levels of fecal 5α-P-3OH and serum P(4) was observed. A random sample of 30 free-ranging female elephants showed fecal 5α-P-3OH values of 0.06-23.4 μg g(-1), indicating them to be in different stages of estrous cyclicity. This study is the first to assess the reproductive phases of female Asian elephants based on the correlative-patterns of both the fecal 5α-P-3OH and serum P(4) values over multiple estrous cycles. This has a potential application in the reproductive management and conservation of Asian elephants.

Inhibition of tyrosine phosphorylation of sperm flagellar proteins, outer dense fiber protein-2 and tektin-2, is associated with impaired motility during capacitation of hamster spermatozoa

In mammals, acquisition of fertilization competence of spermatozoa is dependent on the phenomenon of sperm capacitation. One of the critical molecular events of sperm capacitation is protein tyrosine phosphorylation. In a previous study, we demonstrated that a specific epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor, tyrphostin-A47, inhibited hamster sperm capacitation, accompanied by a reduced sperm protein tyrosine phosphorylation. Interestingly, a high percentage of tyrphostin-A47-treated spermatozoa exhibited circular motility, which was associated with a distinct hypo-tyrosine phosphorylation of flagellar proteins, predominantly of Mr 45,000-60,000. In this study, we provide evidence on the localization of capacitation-associated tyrosine-phosphorylated proteins to the nonmembranous, structural components of the sperm flagellum. Consistent with this, we show their ultrastructural localization in the outer dense fiber, axoneme, and fibrous sheath of spermatozoa. Among hypo-tyrosine phosphorylated major proteins of tyrphostin-A47-treated spermatozoa, we identified the 45 kDa protein as outer dense fiber protein-2 and the 51 kDa protein as tektin-2, components of the sperm outer dense fiber and axoneme, respectively. This study shows functional association of hypo-tyrosine-phosphorylation status of outer dense fiber protein-2 and tektin-2 with impaired flagellar bending of spermatozoa, following inhibition of EGFR-tyrosine kinase, thereby showing the critical importance of flagellar protein tyrosine phosphorylation during capacitation and hyperactivation of hamster spermatozoa.

Expression of glucose transporter isoforms and the insulin receptor during hamster preimplantation embryo development

During preimplantation development, embryos of many species are known to express up to five isoforms of the facilitative glucose transporter proteins (GLUT). Development of hamster blastocysts is inhibited by glucose. We therefore investigated GLUT isoform and insulin receptor (IR) expression in hamster preimplantation embryos cultured in glucose-free medium from the 8-cell stage onwards. We show that GLUT1, 3 and 8 mRNA are constitutively expressed from the 8-cell to the blastocyst stage. The IR is expressed from the morula stage onwards. Messenger RNA of the insulin-responsive GLUT4 was not detected at any stage. GLUT1 and 3 were localised by immunocytochemistry. GLUT1 was expressed in both embryoblast and trophoblast, in the latter, mainly in basal and lateral membranes directed towards the blastocoel and embryoblast. GLUT3 was exclusively localised in the apical membrane of trophoblast cells. We show that hamster preimplantation embryos express several GLUT isoforms thus closely resembling embryos of other mammalian species. Despite endogenous IR expression, the insulin-sensitive isoform GLUT4 was not expressed, indicating that the insulin-mediated glucose uptake known from classical insulin target cells may not be relevant for hamster blastocysts.

Embryo-endometrial expression of leukemia inhibitory factor in the golden hamster (Mesocricetus auratus): increased expression during proestrous and window of implantation stages

Leukemia inhibitory factor (LIF) is a pleiotropic IL-6 family cytokine and its maternal uterine expression is critical for mouse blastocyst implantation. In the golden hamster (Mesocricetus auratus), although the blastocyst hatching phenomenon is quite interesting and LIF is shown to regulate hatching, information is not available on the embryonic and uterine expression of LIF and hormonal regulation of LIF expression during the peri-implantation period. The present investigation is aimed at studying embryonic and uterine expression of LIF during preimplantation hamster development. We observed embryonic expression of LIF mRNA and protein in the 8-cell, morula and blastocyst stages. In cycling females, uterine LIF mRNA expression was maximal during the oestrogen-dominant phase of the oestrous cycle, i.e. proestrous stage. Interestingly, during pregnancy, both LIF mRNA and protein were highly upregulated on Days 3.5 and 4 (‘window of implantation’), implying a role for this cytokine in blastocyst hatching and implantation. Cell type-specific localisation of LIF mRNA and protein was observed predominantly in luminal epithelium and uterine glands with faint staining being detected in the stroma. The hamster uterus encoded a ~4.2 kb LIF transcript whose coding region, when cloned and sequenced, showed a high degree of identity to the murine cDNA counterpart. These data demonstrate that: (1) hamster preimplantation embryos show LIF mRNA and protein expression; (2) uterine expression of LIF mRNA and protein was dependent on elevated levels of circulating oestrogen, and (3) there is a possible functional association of LIF with the peri-implantation development in the golden hamster.

Chemoprevention of rat mammary carcinogenesis by black tea polyphenols: modulation of xenobiotic-metabolizing enzymes, oxidative stress, cell proliferation, apoptosis, and angiogenesis

Chemoprevention of dietary constituents has emerged as a cost-effective approach to control the incidence of breast cancer. The present study was therefore designed to evaluate the chemopreventive efficacy of black tea polyphenols (Polyphenon-B) during the preinitiation phase of 7,12-dimethylbenz[a]anthracene (DMBA) induced mammary carcinogenesis using xenobiotic-metabolizing enzymes, cellular redox status, cell proliferation, apoptosis, and angiogenesis as biomarkers of chemoprevention. Intragastric administration of DMBA induced adenocarcinomas that showed enhanced activities of phase I carcinogen activation and phase II detoxification enzymes with increased lipid and protein oxidation and decrease in antioxidant status. This was associated with increased cell proliferation, angiogenesis, and evasion of apoptosis as revealed by upregulation of proliferating cell nuclear antigen (PCNA), Bcl-2, and vascular endothelial growth factor (VEGF), and downregulation of Bax, caspase 3, and poly(ADP-ribose) polymerase (PARP). Dietary administration of Polyphenon-B effectively suppressed the incidence of mammary tumors as evidenced by modulation of xenobiotic-metabolizing enzymes and oxidant-antioxidant status, inhibition of cell proliferation and angiogenesis, and induction of apoptosis. The present study provides evidence that Polyphenon-B exerts multifunctional inhibitory effects on DMBA-induced mammary carcinogenesis and suggests that it can be developed as a potential chemopreventive agent.

Pentoxifylline improves sperm capacitation and in vitro fertilization of oocytes in the golden hamster

Pentoxifylline (PF) is used to improve motility of spermatozoa from subfertile or nonfertile males to accomplish in vitro fertilization in humans. The possible adverse effect of PF on pre- and peri-implantation stage embryo development in a suitable rodent model, such as the golden hamster, is yet to be determined. In this study, hamster cauda epididymal spermatozoa were exposed to different concentrations (0.23 to 3.6 mM) of PF, and their quantitative [percentage of motility] and qualitative [Score 0 to 5] motility were assessed and values expressed as the sperm motility index. Upon addition of spermatozoa to dishes containing PF, an immediate increase in sperm motility and sperm motility index was evident, which increased up to 4 to 6 h and then declined. The sperm motility index increase by PF was dose-dependant, and >or= 1.8 mM PF was detrimental after 4 h. The optimum dose of PF was found to be 0.45 mM. To assess the fertilizing ability of PF-treated spermatozoa, in vitro fertilization was carried out. Fertilization rates for spermatozoa treated with 3.6 mM PF were lower (53.8 +/- 7.8) than for the controls (69.5 +/- 10.2), whereas treatment with 0.45 mM PF increased the rates (91.6 +/- 4.3) compared with that of the controls (80.2 +/- 5.9). In conclusion, low concentrations (0.23 to 0.45 mM) of PF improve sperm capacitation and fertilization of oocytes in vitro in the golden hamster.

Tyrosine phosphorylated proteins in mammalian spermatozoa: molecular and functional aspects

During mammalian fertilization, spermatozoa must undergo capacitation and the acrosome reaction. These processes of sperm function are critically associated with various molecular events and one such process is protein tyrosine phosphorylation (PYP). This event is downstream of increases in intracellular Ca2+ and activities of HCO3- activated adenylate cyclase, cAMP-dependent-protein kinase-A and reactive oxygen species. Though, PYP is known to be mediated by tyrosine kinases and phosphatases, only a few of them have been identified and characterized in spermatozoa. Since most identified tyrosine kinases are soluble proteins from somatic cells, it is believed that distinct mechanisms could exist in spermatozoa for PYP. Such sperm-specific protein tyrosine kinases/ phosphatases still remain to be thoroughly characterized in most species, including hamsters. Nevertheless, a few tyrosine phosphorylated sperm proteins have been identified in hamsters and in other mammals as well. There is very limited information available on our understanding of the molecular and ultrastructural localization, as well as the characteristics of tyrosine phosphorylated proteins. Functionally, how sperm motility is regulated by PYP is also poorly understood. Knowledge of tyrosine phoshorylated proteins and how they regulate sperm function is of immense significance in our understanding of male (in)fertility and clinical management of fertility; especially, in the light of studies that implicate the hypo-tyrosine phosphorylated state of sperm proteins with asthenozoospermic condition in humans. This article provides a comprehensive review on PYP and its regulation by kinases and phosphatases.

Tyrphostin-A47 inhibitable tyrosine phosphorylation of flagellar proteins is associated with distinct alteration of motility pattern in hamster spermatozoa

To acquire fertilizing potential, mammalian spermatozoa must undergo capacitation and acrosome reaction. Our earlier work showed that pentoxifylline (0.45 mM), a sperm motility stimulant, induced an early onset of hamster sperm capacitation associated with tyrosine phosphorylation of 45-80 kDa proteins, localized to the mid-piece of the sperm tail. To assess the role of protein tyrosine phosphorylation in sperm capacitation, we used tyrphostin-A47 (TP-47), a specific protein tyrosine kinase inhibitor. The dose-dependent (0.1-0.5 mM) inhibition of tyrosine phosphorylation by TP-47 was associated with inhibition of hyperactivated motility and 0.5 mM TP-47-treated spermatozoa exhibited a distinct circular motility pattern. This was accompanied by hypo-tyrosine phosphorylation of 45-60 kDa proteins, localized to the principal piece of the intact-sperm and the outer dense fiber-like structures in detergent treated-sperm. Sperm kinematic analysis (by CASA) of spermatozoa, exhibiting circular motility (at 1st hr), showed lower values of straight line velocity, curvilinear velocity and average path velocity, compared to untreated controls. Other TP-47 analogues, tyrphostin-AG1478 and -AG1296, had no effect either on kinematic parameters or sperm protein tyrosine phosphorylation. These studies indicate that TP-47-induced circular motility of spermatozoa is compound-specific and that the tyrosine phosphorylation status of 45-60 kDa flagellum-localized proteins could be key regulators of sperm flagellar bending pattern, associated with the hyperactivation of hamster spermatozoa.

Germ cell-specific localization of immunoreactive riboflavin carrier protein in the male golden hamster: appearance during spermatogenesis and role in sperm function

Riboflavin carrier protein (RCP) is a phosphoglycoprotein (37 kDa) that is well studied in chicken. An immunologically cross-reacting protein was identified in mammals and active immunization of male rats and bonnet monkeys with chicken RCP lead to an approximately 80% reduction in fertility. However, the physiological mechanism responsible for inhibition of male fertility has not been investigated. Moreover, information on the cell type-specific localization and the origin of immunoreactive RCP during spermatogenesis is extremely limited. Hence, studies were carried out to determine the pattern of expression of immunoreactive RCP during spermatogenesis and its role in sperm function in the golden hamster. Immunoreactive RCP was germ cell-specific, found to be associated with the acrosome-organizing region of early spermatids and showed interesting patterns of immunolocalization during late stages of spermiogenesis. Mature spermatozoa exhibited acrosome-specific localization, mainly in the peri-acrosomal membrane. The immunoreactive protein was undetectable in (non)gonadal somatic cells tested. The protein had a molecular mass of 45-55 kDa and was biosynthesized by round spermatids. The acrosome-specific localization of immunoreactive RCP was unchanged during capacitation, but it was substantially lost during acrosome reaction. Functional studies indicated that treatment of spermatozoa with anti-RCP antibodies did not have any effect on either capacitation or acrosome reaction, but markedly reduced the rate of sperm penetration into zona-free hamster oocytes. These results show the existence of male germ cell-specific immunoreactive RCP, having a potential role in sperm-egg interaction in hamsters. Also the pattern of immunoreactive-RCP localization makes it an ideal marker to monitor development of acrosome in mammalian spermatozoa.

Impact of embryonic expression of enhanced green fluorescent protein on early mouse development

The impact of embryonic enhanced green fluorescent protein (EGFP)-expression on development is not clear. In this study, we comprehensively assessed EGFP-expression pattern and its effect on early mouse development, following pronuclear-microinjection of the EGFP-transgene, containing chicken-beta-actin promoter and cytomegalovirus enhancer. Preimplantation embryos exhibited differential EGFP-expression patterns. While blastocyst development of non-expressing embryos was 77.3+/-1.8%, that of expressing embryos was only 43.9+/-1.6% (P<0.0001). Developmental competence of embryos negatively correlated (r=-0.99) with the levels of EGFP-expression. Faint-, moderate-, and intense-expressing embryos developed to 83.1+/-5.3%, 50+/-5%, and 9.5+/-3.9% blastocysts, respectively (P<0.002). Interestingly, blastocysts expressing faint-moderate levels of EGFP were developmentally competent through the post-implantation period and delivered viable transgenic 'green' mice, following embryo transfer. These results indicate that hyper-expression of EGFP affects preimplantation development and faint-moderate level of its expression is compatible with normal embryogenesis in the mouse.

Embryo-endometrial proteases during early mammalian development

In mammals, extensive remodeling of uterine endometrial matrix occurs during reproductive cycle and blastocyst implantation. This is regulated by a variety of molecules such as hormones, growth factors, cytokines and proteases. In this article, we review the current state of knowledge available on various proteases and their inhibitors functionally involved in the embryo-endometrial tissues and present some data on endometrial proteases in hamsters and rats during estrous cycle and early pregnancy. We demonstrate the presence of at least four gelatinolytic activities in endometrial samples, belonging to gelatinase-A and -B categories and their dependence on calcium/zinc ions for enzyme activity and, their interrelationships between zymogen and active forms. We believe that the embryo-endometrial proteases are essential for hatching of blastocysts and for the dynamic remodeling of endometrial tissues, occurring during the critical peri-implantation period.

Successful development of viable blastocysts from enhanced green fluorescent protein transgene-microinjected mouse embryos: comparison of culture media

To improve efficiency of transgenesis, we compared M16 and CZB embryo culture media, supporting development to blastocysts of FVB/N mouse pronuclear-eggs, microinjected with enhanced green fluorescent protein (EGFP) transgene. When EGFP-injected-eggs were cultured (120 hr), blastocyst development was significantly (P < 0.03) higher in M16 medium (72.5 +/- 2.4%) than that in CZB (13.2 +/- 4.3%) or CZBG (CZB with 5.6 mM glucose at 48 hr culture) (62.1 +/- 3.7%) media. Blastocyst development of noninjected embryos was higher in M16 (92.0 +/- 2.6%) and CZBG (83.9 +/- 3.9%) media than in CZB (31.9 +/- 2.8%) medium (P < 0.0001). However, percentages of morulae at 72 hr were comparable in all treatments. Developed blastocysts were better in M16 than in CZB or CZBG media. Consistent with this, mean cell number per blastocyst, developed from injected embryos, was significantly (P < 0.002) higher in M16 medium (79.6), than those in CZB (31.3) or CZBG media (60.7); similar with noninjected embryos. Cell allocation to trophectoderm (TE) and inner cell mass (ICM), i.e., TE:ICM ratio, for injected blastocysts in M16 (3.0) was less than (P < 0.05) those in CZB (4.2) and CZBG (4.4) media; similar with noninjected blastocysts. Moreover, blastocysts, developed in M16 and CZBG media, hatched, attached, and exhibited trophoblast outgrowth; 18% of them showed EGFP-expression. Importantly, blastocysts from M16 medium produced live transgenic "green" pups (11%) following embryo transfer. Taken together, our results indicate that supplementation of glucose, at 48 hr of culture (CZBG), is required for morula to blastocyst transition; M16 medium, containing glucose from the beginning of culture, is superior to CZB or CZBG for supporting development of biologically viable blastocysts from EGFP-transgene-injected mouse embryos.

Heparin binding-epidermal growth factor improves blastocyst hatching and trophoblast outgrowth in the golden hamster

The effect of heparin binding-epidermal growth factor (HB-EGF) on the in-vitro development of hamster 8-cell embryos was investigated. Supplementation of HB-EGF to culture medium accelerated zona escape of blastocysts (63 +/- 9% compared with 33 +/- 9% after 36 h; P < 0.05). Complete zona escape of blastocysts persisted even after 48 h (61 +/- 11% versus 30 +/- 4%) and 60 h (75 +/- 6% versus 42 +/- 8%). Addition of anti-HB-EGF antibody drastically reduced the percentage of zona escaped-blastocysts (30.0 +/- 5.0% versus 92.3 +/- 2.8%; P < 0.05). Interestingly, a significant increase in the area of trophoblast outgrowth occurred in the presence of HB-EGF (116 x 10(3) +/- 8 x 10(3) microm(2) versus 74 x 10(3) +/- 8 x 10(3) microm(2) at 48 h; P < 0.05). This, however, was not due to an increased number of trophectodermal cells in HB-EGF-treated blastocysts. Immunoreactive HB-EGF was localized in blastocysts and uterine sections, visible by intense immunostaining in the luminal epithelium, particularly on the apical surface. Moreover, the expression of HB-EGF in the uterus was maximum on day 4 of pregnancy, coinciding with the timing of zona escape and implantation. The receptor of HB-EGF, viz. EGF receptor was also detected in blastocysts and the luminal epithelium of day 4 pregnant uterus. These results show that HB-EGF improves blastocyst hatching and trophoblast outgrowth in hamsters.

Pentoxifylline induced signalling events during capacitation of hamster spermatozoa: significance of protein tyrosine phosphorylation

To fertilize the oocyte, mammalian spermatozoa must undergo capacitation and acrosome reaction. These events are believed to be associated with various biochemical changes primarily mediated by cAMP, Ca2+ and protein kinases. But the precise signaling mechanisms governing sperm function are not clear. To study this, we used pentoxifylline (PF), a sperm motility stimulant and a cAMP-phosphodiesterase inhibitor, during capacitation and acrosome reaction of hamster spermatozoa. PF induced an early onset of sperm capacitation and its action involved modulation of sperm cell signaling molecules viz, cAMP, [Ca2+]i and protein kinases. The PF-induced capacitation was associated with an early and increased total protein phosphorylation coupled with changes in the levels of reactive oxygen species. Protein kinase (PK)-A inhibitor (H-89) completely inhibited phosphorylation of a 29 kDa protein while PK-C inhibitor (staurosporine) did not inhibit phosphorylation. Interestingly, PF induced protein tyrosine phosphorylation of a set of proteins (Mr 45-80 K) and a greater proportion of PF-treated spermatozoa exhibited protein tyrosine phosphorylation, compared to untreated controls (82 + 9% vs 34 +/- 10%; p < 0.001); tyrosine-phosphorylated proteins were localized specifically to the mid-piece of the sperm. The profile of protein tyrosine phosphorylation was inhibitable by higher concentrations (> 0.5 mM) of tyrosine kinase inhibitor, tyrphostin A47. However, at lower (0.1-0.25 mM) concentrations, the compound interestingly induced early sperm capacitation and protein tyrosine phosphorylation, like PF. These results show that protein tyrosine phosphorylation in the mid-piece segment (mitochondrial sheath) appears to be an early and essential event during PF-induced capacitation and a regulated level of tyrosine phosphorylation of sperm proteins is critical for capacitation of hamster spermatozoa.

Embryo culture-based generation of enhanced green fluorescent protein-transgenic mice

One of the limitations of transgenesis is low efficiency. In this study, we generated transgenic mice harboring the enhanced green fluorescent protein (EGFP) gene, under the control of chicken-beta-actin promoter and cytomegalovirus enhancer, using two approaches and compared their efficiencies. One involved culture of EGFP-injected embryos developing through EGFP-expressing "green" blastocysts, followed by their transfer to uterus. The second was oviductal-transfer of EGFP-injected-eggs. Embryo culture-based-transgenesis (ECBT) produced 100% transgenic mice, unlike the second approach. Moreover, ECBT required reduced number of recipients and markedly increased pregnancy rates. Of the nine founders, seven exhibited ubiquitous EGFP-expression, one (GU1) was a mosaic and the other (G18) was non-expressing. The molecular basis for this was attributed to repeat-induced gene silencing, since the G18 had a high copy number (approximately 99/genome) of the non-mutated and non-rearranged EGFP-transgene integrated at a single site. Our results show the superiority of ECBT over the conventional oviductal approach for generating transgenic "green" mice.

Differential influence of recombinant non-glycosylated and glycosylated glycodelin on human sperm function: comparative studies with hamster spermatozoa

Glycodelin, also known as placental protein 14, has been implicated in endometriosis-related infertility. To determine the role of glycodelin and its glycosylated state, the influence of recombinant nonglycosylated-glycodelin (nongly-glycodelin) and glycosylated-glycodelin (gly-glycodelin) on human sperm function was evaluated. Whereas there was a significant (P<0.001) increase in the capacitation of nongly-glycodelin-treated spermatozoa compared with untreated controls (28.8 +/- 1.0% v. 21 +/- 1.5% respectively), treatment of spermatozoa with gly-glycodelin markedly (P<0.001) inhibited capacitation (10.7 +/- 0.3%); acrosome reaction (AR) remained unaltered in all treatments. In a zona-free hamster egg penetration assay, the egg penetration index was higher (P<0.001) with nongly-glycodelin-treated spermatozoa (3.4 +/- 0.3) than with gly-glycodelin-treated spermatozoa (0.4 +/- 0.1) and untreated spermatozoa (1.6 +/- 0.2). A similar influence of glycodelin on capacitation was observed with hamster spermatozoa. However, the AR rate was higher (P<0.01) in nongly-glycodelin-treated spermatozoa (39.4 +/- 1.6%) than in either gly-glycodelin-treated spermatozoa (19.3 +/- 2.0%) or untreated controls (30.0 +/- 1.2%). Moreover, the in vitro fertilization rate was significantly (P<0.01) higher with nongly-glycodelin treated-spermatozoa compared with untreated spermatozoa (77.5 +/- 2.3% v. 52.9 +/- 4.3%) and gly-glycodelin-treated spermatozoa (38.3 +/- 6.5%; P<0.05). These results indicate that whereas nongly-glycodelin improves, gly-glycodelin inhibits, capacitation and fertilization potential of human and hamster spermatozoa, and that the glycosylation status of glycodelin determines its influence on sperm function.

Regulation of peri-attachment embryo development in the golden hamster: role of growth factors

The molecular regulation of mammalian peri-implantation development is complex and difficult to study in vivo. We successfully cultured hamster blastocysts through hatching and peri-attachment stages, using a chemically defined medium, HECM-2h. Using this system, we showed that a species-specific, embryonic cysteine-like protease is involved in blastocyst hatching and that the process is modulated by growth factors. In particular, heparin binding-epidermal growth factor (HB-EGF) or leukemia inhibitory factor (LIF) enhance blastocyst hatching, and the former also improves attachment and trophoblast outgrowth. We observed interesting changing patterns of expression of mRNA and/or immunoreactive protein for EGF, HB-EGF, LIF and transforming growth factor-beta (TGF-beta) in the embryo and/or endometrial tissue, during peri-implantation development. Together, it appears that hamster blastocyst hatching, attachment and trophoblast outgrowth are regulated by autocrine and/or paracrine growth factors, produced by the embryo-endometrial tissues.

Molecular insights into the causes of male infertility

Infertility is a reproductive health problem that affects many couples in the human population. About 13-18% of couple suffers from it and approximately one-half of all cases can be traced to either partner. Regardless of whether it is primary or secondary infertility, affected couples suffer from enormous emotional and psychological trauma and it can constitute a major life crisis in the social context. Many cases of idiopathic infertility have a genetic or molecular basis. The knowledge of the molecular genetics of male infertility is developing rapidly, new "spermatogenic genes" are being discovered and molecular diagnostic approaches (DNA chips) established. This will immensely help diagnostic and therapeutic approaches to alleviate human infertility. The present review provides an overview of the causes of human infertility, particularly the molecular basis of male infertility and its implications for clinical practice.

Evidence for the involvement of a species-specific embryonic protease in zona escape of hamster blastocysts

The source and nature of zona lytic factors during zona escape of hamster blastocyts were investigated. When cultured in hamster embryo culture medium (HECM)-2h, all 8-cell embryos (n = 135) developed to zona escaped-blastocysts with complete zona lysis. In addition, 2-cell embryos, when co-cultured with zona escaping-blastocysts (at a ratio of 1:10), exhibited zona lysis. Various other embryos at the 1-8-cell stages also showed zona lysis when cultured with zona-escaping blastocysts. However, zonae from mice, rats, sheep and humans were resistant to lysis under these conditions. Pronase treatment resulted in rapid zona lysis in hamsters (7 +/- 1 s), whereas in other species zona lysis was much slower: mouse (662 +/- 27 s), rat (532 +/- 16 s), sheep (120 +/- 12 s) and human (104 +/- 8 s). When cysteine protease inhibitors (antipain, leupeptin, E-64 and p-hydromercuricbenzoate) were tested, they completely inhibited zona escape, while trypsin inhibitors (TLCK and SBTI) did not. Uterine zona lysin contribution in zona escape was discounted since: (i) uterine luminal flushing and endometrial extract from day 4 (the time of zona escape in vivo) pregnant females failed to lyse zonae and (ii) endogenous oocytes and transferred 2-cell embryos (to day 3 pseudopregnant recipients) were all zona-intact, while 71% of transferred blastocysts exhibited zona escape, following their recovery after 24 h. These observations suggest that a species-specific, embryonic proteolytic factor, with a cysteine protease-like activity, is involved in the zona escape of blastocysts in hamsters.

Active immunization against riboflavin carrier protein results in peri-implantation embryonic loss leading to pregnancy termination in rats: use of alternate adjuvants

To investigate the mechanism of pregnancy termination following immuno-neutralization of riboflavin carrier protein (RCP) and to use acceptable adjuvants, we actively immunized female rats with reduced and carboxymethylated RCP (RCM-RCP) using various adjuvants (during primary immunization) such as sodium phthalylated lipopolysaccharide (SPLPS), purified S. typhi outer membrane proteins (porins) and a combination of them. Rats (5-14 per group) were immunized with alugel adsorbed RCM-RCP (100 microg/dose) either alone or with SPLPS or porins or SPLPS+porins. Control animals received RCM-RCP emulsified with Fruend's completelincomplete adjuvants (FCA/FIA). All animals received five boosters at intervals of 21 days. The lowest (4 X 10(-3)) and the highest (> 70 X 10(-3)) anti-RCM-RCP antibody titers were observed in alugel adsorbed-RCM-RCP group and control groups, respectively. Immunized animals showed reduced fertility following 3rd, 4th and 5th boosters. Reduction in fertility was 30-60% in alugel adsorbed RCM-RCP group, 90-100% in FCA-RCM-RCP group and 80-90% in SPLPS+porins group. Fertility reduction was not strictly correlatable with the serum antibody titers. RCP-specific IgG could be localized in the uterine endometrial glands and luminal epithelial cells in the immunized animals. Animals in the FCA/FIA group showed abnormal implantation/resorption sites and their histological sections showed degenerated embryos. But, day 5 preimplantation embryos were normal. These results show that (a) SPLPS+porins can be used as adjuvants in place of FCA/FIA for active immunization against RCM-RCP and (b) early termination of pregnancy in the immunized animals is due largely to the failure of normal embryo implantation.

Sperm-mediated gene transfer into oocytes of the golden hamster: assessment of sperm function

The possibility of sperm as a vehicle to deliver foreign DNA to oocytes was tested in hamsters. Epididymal spermatozoa, incubated with linearized plasmid DNA encoding ovine growth hormone (pCMXoGH), showed a spontaneous tendency to interact with DNA. Kinetics of sperm uptake of DNA was determined by using [32P]-labeled DNA. Spermatozoa took up the added DNA by 15-30 min and the uptake was inhibited by human seminal fluid in a dose dependent manner. Addition of DNA did not affect the functional competence of spermatozoa, in terms of their ability to undergo capacitation and acrosome reaction (34.5% +/- 2.2 vs 35% +/- 1.5). The fertilizing ability of DNA treated-spermatozoa from hamsters and humans was assessed by zona-free hamster egg penetration assay. Number of sperm penetrated per oocyte were 23 +/- 4.5 and 1.4 +/- 1.3 for hamster and human spermatozoa, respectively. Penetrated oocytes harbored sperm-treated DNA both with hamster (30.2 cpm/oocyte) and human (19.2 cpm/oocyte) spermatozoa. These results show that the hamster and human spermatozoa have a strong tendency to interact with exogenous (foreign) DNA and are able to transfer DNA to oocytes. Sperm may be used as a vector for DNA transfer and this approach has potential in the production of transgenic animals.

Successful development in vitro of hamster 8-cell embryos to 'zona-escaped' and attached blastocysts: assessment of quality and trophoblast outgrowth

The peri-implantation development involves zona escape (hatching) of blastocysts and their attachment and proliferation. These events are difficult to study in vivo, so in this study hamster 8-cell embryos were cultured through the hatched and attached blastocyst stages using different formulations of hamster embryo culture medium (HECM)-2. Supplementation of succinate, amino acids, vitamins (inositol, pantothenate, choline chloride) and bovine serum albumin (BSA) to HECM-2 supported 100% development of 'zona-escaped' blastocysts. In this medium (designated as hatching, i.e. HECM-2h) all blastocysts invariably deflated and escaped from focally lysed zonae, which underwent complete dissolution. In their presence, pre-morula stage embryos also escaped from zonae. Omission of BSA from HECM-2h failed to support zona escape whereas that of vitamins reduced zona escape (34.0% +/- 7.0). Blastocysts with the potential to undergo zona escape in HECM-2h were of high quality as they had a higher mean cell number (MCN) than the MCN of those developing in BSA-free HECM-2h (35.2 +/- 1.6 v. 24.3 +/- 1.1). Cell allocation (i.e. trophectoderm to inner cell mass ratio) in blastocysts remained unaltered in both media (2.6 +/- 0.2 v. 2.7 +/- 0.2). Supplementation of 10% bovine fetal serum (BFS) to HECM-2h was detrimental to the development of blastocysts (22.3% +/- 7.4) and none of them underwent zona escape. Interestingly, BFS was required either as a supplement to the medium or as a coating on dishes for azonal blastocysts to attach (> or = 70%) and exhibit trophoblast (TB) outgrowth (30.3 x 10(3) +/- 2.9 x 10(3) micron 2 at 48 h). These results show that HECM-2h supports maximal development of zona-escaped blastocysts with the potential to attach and exhibit TB outgrowth, and there is a developmental stage-specific requirement for serum during peri-attachment in hamster development.