Allometric growth ratios are independent of Igf2 gene dosage during development

In the mouse, allelic dosage of the paternally expressed gene coding for insulin-like growth factor II (Igf2), from null to bi-allelic, results in dose-dependent growth, an effect which appears to be fully established during a discrete period of embryogenesis that then persists throughout life. Here, we specifically quantify the influence of Igf2 allelic dosage on the proportionality of regional embryonic growth rather than overall growth. Remarkably, preservation of allometric growth ratios between head and body regions were observed throughout development, irrespective of the range of overall growth phenotype (60-130% of wild type). Evaluation of log-log plots suggests that each allele of Igf2 expressed corresponds to the equivalent of 2-4 days of relative growth. Igf2 is predominantly expressed in extra-embryonic mesoderm (E7.5-E8.25), 24 h before alterations in cell number are known to occur in embryos with disruption of the paternally expressed allele. We hypothesized that the preservation of proportionality may result from modification of extra-embryonic development and subsequent alteration of systemic nutritional supply. Morphological analyses of chorio-allantoic and placental development between E9 and E9.5 appeared Igf2 independent. This suggests either an intrinsic but systemic Igf2-dependent activity within the embryo or a more complex developmental mechanism accounts for the proportional phenotype. Allelic IGF2 expression is subject to stochastic variation in humans, with 10% of the population estimated to be functionally bi-allelic. Evaluation of allometric growth of normal and pathological human embryos, suggest intra-uterine growth phenotypes associated with altered IGF2 imprinting are also likely to be proportionate.

An adenosine triphosphatase of the sucrose nonfermenting 2 family, androgen receptor-interacting protein 4, is essential for mouse embryonic development and cell proliferation

An adenosine triphosphatase of the sucrose nonfermenting 2 protein family, androgen receptor-interacting protein 4 (ARIP4), modulates androgen receptor activity. To elucidate receptor-dependent and -independent functions of ARIP4, we have analyzed Arip4 gene-targeted mice. Heterozygous Arip4 mutants were normal. Arip4 is expressed mainly in the neural tube and limb buds during early embryonic development. Arip4-/- embryos were abnormal already at embryonic d 9.5 (E9.5) and died by E11.5. At E9.5 and E10.5, almost all major tissues of Arip4-null embryos were proportionally smaller than those of wild-type embryos, and the neural tube was shrunk in some Arip4-/- embryos. Dramatically reduced cell proliferation and increased apoptosis were observed in E9.5 and E10.5 Arip4-null embryos. Mouse embryonic fibroblasts (MEFs) isolated from Arip4-/- embryos ceased to grow after two to three passages and exhibited increased apoptosis and decreased DNA synthesis compared with wild-type MEFs. Comparison of gene expression profiles of Arip4-/- and wild-type MEFs at E9.5 revealed that putative ARIP4 target genes are involved in cell growth and proliferation, apoptosis, cell death, DNA replication and repair, and development. Collectively, ARIP4 plays an essential role in mouse embryonic development and cell proliferation, and it appears to coordinate multiple essential biological processes, possibly through a complex chromatin remodeling system.

Cbfa-1 mediates nitric oxide regulation of MMP-13 in osteoblasts

During bone development, osteoblast differentiation requires remodeling of the extracellular matrix. Although underlying mechanisms have not been elucidated, evidence points to the participation of the nitric oxide (NO) and cyclic guanosine 3',5'-monophosphate (cGMP) system. Here, we detected increased matrix metalloproteinase (MMP)-13 mRNA, protein and activity, as well as increased inducible NO synthase (iNOS) and NO production during the differentiation of MC3T3-E1 osteoblasts. Transcriptional activity of the MMP-13 promoter was augmented by NO, 8-bromo-cGMP (8-Br-cGMP), and by a dominant-positive form of protein kinase G (PKG1-alpha). The stimulatory effect on the MMP-13 promoter was partially inhibited by mutation of the osteoblast-specific element 2 (OSE-2) binding site. Core binding factor-1 (Cbfa-1) expression peaked at 7 days of differentiation, and was phosphorylated by PKG in vitro. Cbfa-1 was localized to cell nuclei, and its translocation was inhibited by the iNOS inhibitor 1400W. Immunohistological examination revealed that MMP-13 and Cbfa-1 expression levels are both reduced in 17-day-old embryos of iNOS-deficient mice. Silencing of Cbfa-1 mRNA blocked MMP-13 expression without interfering with endogenous NO production, confirming its role in NO-induced MMP-13 expression by MC3T3-E1 cells. The results described here suggest a mechanism by which NO regulates osteogenesis.

High bone morphogenetic protein-15 level in follicular fluid is associated with high quality oocyte and subsequent embryonic development

BACKGROUND

Bone morphogenetic protein-15 (BMP-15) has been shown to influence oocyte maturation and quality. However, no relationship has been established between BMP-15 and oocyte quality/embryonic development in humans. The aim of this study is to investigate BMP-15 level in human follicular fluid (FF) and its possible role in determining oocyte quality and developmental potential.

METHODS

A total of 79 oocytes and their corresponding FF from 79 women undergoing ICSI were examined. Individual oocytes were inseminated and subsequently assessed on the basis of their fertilization, cleavage and preimplantation development. BMP-15, FSH, estradiol (E(2)) and progesterone levels of FF were also analysed via the techniques of western blot or radioimmunoassay.

RESULTS

Higher FF BMP-15 levels were observed in the fertilized and cleaved groups versus the unfertilized and uncleaved groups, respectively (P < 0.05). The best (Grade I) embryo morphology was associated with higher FF BMP-15 levels than Grade II or III embryos (P < 0.01). A significant positive correlation was found between BMP-15 and E(2) levels in the same follicle.

CONCLUSION

The present study demonstrates that the BMP-15 level in FF appears to be a potential factor in predicting oocyte quality and subsequent embryo development, and is correlated with E(2) level, which may additionally be a valuable predictor of oocyte fertilization.

The allantois and chorion, when isolated before circulation or chorio-allantoic fusion, have hematopoietic potential

The chorio-allantoic placenta forms through the fusion of the allantois (progenitor tissue of the umbilical cord), with the chorionic plate. The murine placenta contains high levels of hematopoietic stem cells, and is therefore a stem cell niche. However, it is not known whether the placenta is a site of hematopoietic cell emergence, or whether hematopoietic cells originate from other sites in the conceptus and then colonize the placenta. Here, we show that the allantois and chorion, isolated prior to the establishment of circulation, have the potential to give rise to myeloid and definitive erythroid cells following explant culture. We further show that the hematopoietic potential of the allantois and chorion does not require their union, indicating that it is an intrinsic property of these tissues. These results suggest that the placenta is not only a niche for, but also a source of, hematopoietic cells.

Evx2-Hoxd13 intergenic region restricts enhancer association to Hoxd13 promoter

Expression of Hox genes is tightly regulated in spatial and temporal domains. Evx2 is located next to Hoxd13 within 8 kb on the opposite DNA strand. Early in development, the pattern of Hoxd13 expression resembles that of Evx2 in limb and genital buds. After 10 dpc, however, Evx2 begins to be expressed in CNS as well. We analyzed the region responsible for these differences using ES cell techniques, and found that the intergenic region between Evx2 and Hoxd13 behaves as a boundary element that functions differentially in space and time, specifically in the development of limbs, genital bud, and brain. This boundary element comprises a large sequence spanning several kilobases that can be divided into at least two units: a constitutive boundary element, which blocks transcription regulatory influences from the chromosomal environment, and a regulatory element, which controls the function of the constitutive boundary element in time and space.

High-efficiency FLP and PhiC31 site-specific recombination in mammalian cells

DNA site-specific recombinases (SSRs) such as Cre, FLPe, and φC31, are powerful tools for analyzing gene function in vertebrates. While the availability of multiple high-efficiency SSRs would facilitate a wide array of genomic engineering possibilities, efficient recombination in mammalian cells has only been observed with Cre recombinase. Here we report the de novo synthesis of mouse codon-optimized FLP (FLPo) and ΦC31 (ΦC31o) SSRs, which result in recombination efficiencies similar to Cre.

Math1 target genes are enriched with evolutionarily conserved clustered E-box binding sites

The basic helix-loop-helix (bHLH) transcription factor Math1 and its orthologs are fundamental for proper development of various neuronal subpopulations, such as cerebellar granule cells, D1 interneurons in the spinal cord, and inner ear hair cells. Although crucial for neurogenesis, the mechanisms by which Math1 specifically recognizes its direct targets are not fully understood. To search for direct and indirect target genes and signaling pathways controlled by Math1, we analyzed the effect of Math1 knockout on the expression profile of multiple genes in the embryonic cerebellum. Eighteen differentially expressed transcripts were identified and found to belong to a few developmentally-related functional groups, such as transcriptional regulation, proliferation, organogenesis, signal transduction, and apoptosis. Importantly, genomic analysis of E-box motifs has identified a significant enrichment and clustering of MATH1-binding E-boxes only in a subset of differentially expressed genes (Nr2f6, Hras1, and Hes5) in both mouse and man. Moreover, Math1 was shown by chromatin immunoprecipitation (ChIP) to bind, and by a luciferase reporter assay to activate transcription, of an upstream genomic fragment of Nr2f6. Taken together, we propose that when putative direct targets of Math1 are being selected for detailed studies on DNA microarray hybridization, the enrichment and clustering of binding E-boxes in multiple species may be helpful criteria. Our findings may be useful to the study of other bHLH transcription factors, many of which control the development of the nervous system.

Gene expression analysis identifies novel genes participating in early murine liver development and adult liver regeneration

Adult liver tissue regeneration may recapitulate molecular events of liver organogenesis. As gaps in our understanding of the fundamental processes that govern development and regeneration of the liver still exist, we studied gene expression in the developing liver at embryonic day 9.5 post coitum (E d9.5 p.c.). Microarray data from E d9.5 p.c. as well as previously published data from embryonic day 11.5 post coitum (E d11.5 p.c.) and embryonic day 13.5 post coitum (E d13.5 p.c.) were subjected to cluster analysis. This led to the identification of 130 genes which were characterized by continuous expression at all stages of liver development with peak expression of 44 genes at E d9.5 p.c. Five of these genes, previously not known to be associated with early liver development or with adult liver regeneration were selected for further analysis. The expression of the genes was studied by real-time polymerase chain reaction at 0, 2, 4, 6, 12, 24 and 48 hr after partial hepatectomy in the adult liver. Two of the genes, growth arrest protein 43 (GAP43) and paired-like homeodomain transcription factor 2 (Pitx2) were exclusively detected at 24 hr, whereas the genes Twist1, Midkine, and zinc finger protein of cerebellum 1 (Zic1) each showed a specific expression profile in the regenerating liver with peak expressions at 4, 24, and 6 hr, respectively. In summary, we were able to identify novel genes, that may act as regulators during liver formation as well as in the regeneration phase of adult liver. This information may contribute to the development of new targets for the treatment of liver diseases in the future.

Computerized three-dimensional analysis of the heart and great vessels in normal and holoprosencephalic human embryos

The developing heart and great vessels undergo drastic morphogenetic changes during the embryonic period. To analyze the normal and abnormal development of these organs, it is essential to visualize their structures in three and four dimensions, including the changes occurring with time. We have reconstructed the luminal structure of the hearts and great vessels of staged human embryos from serial histological sections to demonstrate their sequential morphological changes in three dimensions. The detailed structures of the embryonic heart and major arteries in normal and holoprosencephalic (HPE) human embryos could be reconstructed and visualized, and anatomical structures were analyzed using 3D images. By 3D analysis, cardiac anomalies such as double-outlet right ventricle and malrotation of the heart tube were identified in HPE embryos, which were not easily diagnosed by histological observation. Reconstruction and analysis of 3D images are useful for the study of anatomical structures of developing embryos and for identifying their abnormalities.

A history of normal plates, tables and stages in vertebrate embryology

Developmental biology is today unimaginable without the normal stages that define standard divisions of development. This history of normal stages, and the related normal plates and normal tables, shows how these standards have shaped and been shaped by disciplinary change in vertebrate embryology. The article highlights the Normal Plates of the Development of the Vertebrates edited by the German anatomist Franz Keibel (16 volumes, 1897-1938). These were a major response to problems in the relations between ontogeny and phylogeny that amounted in practical terms to a crisis in staging embryos, not just between, but (for some) also within species. Keibel's design adapted a plate by Wilhelm His and tables by Albert Oppel in order to go beyond the already controversial comparative plates of the Darwinist propagandist Ernst Haeckel. The project responded to local pressures, including intense concern with individual variation, but recruited internationally and mapped an embryological empire. Though theoretically inconclusive, the plates became standard laboratory tools and forged a network within which the Institut International d'Embryologie (today the International Society of Developmental Biologists) was founded in 1911. After World War I, experimentalists, led by Ross Harrison and Viktor Hamburger, and human embryologists, especially George Streeter at the Carnegie Department of Embryology, transformed Keibel's complex, bulky tomes to suit their own contrasting demands. In developmental biology after World War II, normal stages-reduced to a few journal pages-helped domesticate model organisms. Staging systems had emerged from discussions that questioned the very possibility of assigning an embryo to a stage. The historical issues resonate today as developmental biologists work to improve and extend stage series, to make results from different laboratories easier to compare and to take individual variation into account.

Analysis of integrin functions in peri-implantation embryos, hematopoietic system, and skin

Integrins mediate cell adhesion, permit traction forces important for cell migration, and cross-talk with growth factor receptors to regulate cell proliferation, cell survival, and cell differentiation. The plethora of functions explains their central role for development and disease. The progress in mouse genetics and the ease with which the mouse genome can be manipulated enormously contributed to our understanding of how integrins exert their functions at the molecular level. In the present chapter, we describe tests that are routinely used in our laboratory to investigate embryos, organs, and cells (peri-implantation embryos, hematopoietic system, epidermis, and hair follicles) that lack the expression of integrins or integrin-associated proteins.

Association Between Embryonic Loss and Damage to the Zona Pellucida by Invasive Micromanipulation During Oviductal Transfer of Early-Stage Embryos in Pigs

The aim of this study was to examine the impact of zona pellucida damage, which might arise during somatic cell nuclear transfer (SCNT), on the development and survival of transferred embryos. The zonae pellucidae of in vitro matured oocytes were either punctured with 8- to 10-microm square-ended nuclear injection pipettes and piezo pulses or slit with 35- to 40-microm enucleation pipettes. Intact oocytes were used as controls. These oocytes were electroactivated to induce parthenogenesis and transferred to the oviducts of estrus-synchronized recipient gilts. After 5 to 7 days, the recipient uteri were flushed to collect embryos, and embryonic development (morula-blastocyst stage embryos/collected embryos) and survival (viable embryos/collected embryos) were determined. In total, 221 zona-punctured, 129 zona-slitted and 57 intact embryos were transplanted into four, two and two gilts, respectively. The efficiency of embryo recovery was similar in all groups (64.3 to 79.1%). However, the zona-penetrated and incised embryos exhibited unstable development and survival compared with the controls; development and survival of the control embryos were 94.7 and 87.7%, whereas those of the zona-punctured embryos were 69.0 and 47.9% (P<0.01) and those of the zona-slit embryos were 64.7 and 50.0% (P<0.01). Cells with large foci that appeared to be macrophage giant cells were observed at the surface or inside the degenerated zona-damaged embryos. These results indicate that the recipient's immune response to damage to the zona pellucida may impair embryonic development after transplantation to the oviduct. This may be one of the factors causing the reduced efficiency of live progeny production by SCNT.

Ubiquitin C-terminal hydrolase L1 regulates the morphology of neural progenitor cells and modulates their differentiation

Ubiquitin C-terminal hydrolase L1 (UCH-L1) is a component of the ubiquitin system, which has a fundamental role in regulating various biological activities. However, the functional role of the ubiquitin system in neurogenesis is not known. Here we show that UCH-L1 regulates the morphology of neural progenitor cells (NPCs) and mediates neurogenesis. UCH-L1 was expressed in cultured NPCs as well as in embryonic brain. Its expression pattern in the ventricular zone (VZ) changed between embryonic day (E) 14 and E16, which corresponds to the transition from neurogenesis to gliogenesis. At E14, UCH-L1 was highly expressed in the ventricular zone, where neurogenesis actively occurs; whereas its expression was prominent in the cortical plate at E16. UCH-L1 was very weakly detected in the VZ at E16, which corresponds to the start of gliogenesis. In cultured proliferating NPCs, UCH-L1 was co-expressed with nestin, a marker of undifferentiated cells. In differentiating cells, UCH-L1 was highly co-expressed with the early neuronal marker TuJ1. Furthermore, when UCH-L1 was induced in nestin-positive progenitor cells, the number and length of cellular processes of the progenitors decreased, suggesting that the progenitor cells were differentiating. In addition, NPCs derived from gad (UCH-L1-deficient) mice had longer processes compared with controls. The ability of UCH-L1 to regulate the morphology of nestin-positive progenitors was dependent on its binding affinity for ubiquitin but not on hydrolase activity; this result was also confirmed using gad-mouse-derived NPCs. These results suggest that UCH-L1 spatially mediates and enhances neurogenesis in the embryonic brain by regulating progenitor cell morphology.

Pregnancy prediction models and eSET criteria for IVF patients--do we need more information?

PURPOSE

The purpose of the present study was to evaluate statistical prediction models and simple allocation criteria, based on predictors for pregnancy, as tools to identify a good prognosis group in a possible eSET setting.

METHODS

A pregnancy prediction model based on logistic regression models was generated by analysis of 1675 DET treatment cycles. The model was evaluated and compared to simple eSET allocation criteria.

RESULTS

Embryo quality, patient age, and basal FSH were identified as significant predictors (at 5% significance level) of pregnancy. Although comparable to previously generated models, the predictive ability of the present model was relatively poor and practically similar to simple allocation criteria based on age and embryo quality.

CONCLUSIONS

Existing prediction models, or simple allocation criteria, are limited in identifying good prognosis patients. Future studies of the applicability of improved pregnancy prediction models will need very comprehensive and detailed patient and embryo information.

PPARδ and its activator PGI2 are reduced in diabetic embryopathy: involvement of PPARδ activation in lipid metabolic and signalling pathways in rat embryo early organogenesis

Maternal diabetes significantly increases the risk of congenital malformations, and the mechanisms involved are not yet clarified. This study was designed to address peroxisome proliferator-activated receptor delta (PPARdelta) involvement in diabetic embryopathy. We investigated the concentrations of PPARdelta and its endogenous agonist prostaglandin (PG)I(2), as well as the effect of PPARdelta activation on lipid metabolism and PGE(2) concentrations in embryos from control and streptozotocin-induced diabetic rats during early organogenesis. Embryos from diabetic rats showed decreased concentrations of PPARdelta and its endogenous agonist PGI(2) when compared with controls. In embryos from control rats, the addition of the PPARdelta activators (cPGI(2) and PGA(1)) increased embryonic phospholipid levels and de novo phospholipid synthesis studied using (14)C-acetate as a tracer. PGE(2) formed from arachidonate released from phospholipid stores was also up-regulated by PPARdelta activators. In embryos from diabetic rats, reduced phospholipid synthesis and PGE(2) content were observed, and clearly up-regulated by cPGI(2) additions to values similar to those found in control embryos. These data suggest that PPARdelta may play an important role in lipid metabolic and signalling pathways during embryo organogenesis, developmental pathways that are altered in embryos from diabetic rats, possibly as a result of a reduction in levels of PPARdelta and its endogenous activator PGI(2).

[Theoretical and applied aspects of epigenetic reprogramming in mammalian development]

Epigenetic reprogramming implies changes in germ and somatic cells of an embryo, which are the consequences of gene activity regulation by means of DNA methylation, histone modification, and altered chromatin compaction. This suggests that epigenetic changes in mammalian cell nucleus occur during gametogenesis and toti-potent zygote formation. Epigenetic changes proceed during morphological and inductive interactions between cleaving blastomeres and subsequent interactions between the inner cell contents and trophoectoderm, as well as when the germinal layers (blastophyllums) and their derivatives appear, i.e., during the embryonic histogenesis. Some authors assume that in vitro fertilization and consequent human zygote cultivation lead to defects of genomic imprinting. This leads to abnormal embryonic and fetal development and increased incidence of hereditary diseases-Beckwith-Wiederman or Angelman syndromes. The present review, critically considers the facts on which the above hypothesis is based.

Interobserver and intraobserver variation in day 3 embryo grading

OBJECTIVE

Variations in pregnancy rates (PR) between IVF programs are due to multiple factors, including embryo quality. Standardized embryo grading systems have been developed to improve communication between embryologists and clinicians. However, these grading systems have not been validated. We sought to quantify both interobserver and intraobserver variability using a standardized day 3 embryo grading system (Veeck scale).

DESIGN

Prospective, sample-randomized, controlled, blinded study.

SETTING

University hospital.

PATIENT(S)

Twenty-six practicing embryologists.

INTERVENTION(S)

Observation and grading of 35 video clips of day 3 embryos.

MAIN OUTCOME MEASURE(S)

Interobserver and intraobserver variability. Embryologists were also assessed by education level, years of experience, size of IVF program, and type of grading system used. Kappa scores and intraclass correlation coefficients were calculated.

RESULT(S)

Practicing embryologists differed from control (Lucinda Veeck) by as much as two grades, despite using the same grading system (Kappa = 0.24, interclass correlation coefficient = 0.98). There was also variability in grading the same embryo (Kappa = 0.69, interclass correlation coefficient = 0.88). Programs with higher cycle numbers per year had lower variability.

CONCLUSION(S)

There is substantial interobserver variability and moderate intraobserver variability among embryologists. Such variability could alter both the expected quality of embryos transferred, as well as the number transferred, both of which directly impact IVF program success.

Embryo morphology and development are dependent on the chromosomal complement

OBJECTIVE

To analyze embryo morphology in relation to the corresponding chromosomal status, in order to evaluate the effects of aneuploidy over fragmentation, delayed cleavage, and arrested cleavage.

DESIGN

Retrospective study.

SETTING

Reproductive Medicine Unit, Società Italiana di Studi di Medicina della Riproduzione, Bologna, Italy.

PATIENT(S)

A total of 662 patients with a poor prognosis for pregnancy underwent 916 cycles of preimplantation genetic diagnosis for aneuploidy.

INTERVENTION(S)

The chromosomes XY, 13, 15, 16, 18, 21, and 22 were analyzed in blastomeres biopsied from day 3 embryos.

MAIN OUTCOME MEASURE(S)

Embryo morphology, chromosomal status of the analyzed blastomeres, and spreading and reanalysis of nontransferred embryos.

RESULT(S)

The incidence of chromosomal abnormalities was significantly higher in arrested or slow-cleaving embryos, and in embryos cleaving too fast, compared to embryos with eight cells at 62 hours after insemination. The presence of an uneven number of blastomeres or fragments scattered in the perivitelline space was associated with an increased incidence of chromosomal abnormalities.

CONCLUSION(S)

A correlation between embryo development and chromosomal complement makes the incidence of chromosomal abnormalities significantly higher in embryos dividing according to a time frame and a symmetry plan which are different from what are expected. The type of fragmentation is also related to chromosomal status, which explains why the extrusion of fragments might severely affect embryo viability.

Steel factor controls midline cell death of primordial germ cells and is essential for their normal proliferation and migration

During germ-cell migration in the mouse, the dynamics of embryo growth cause many germ cells to be left outside the range of chemoattractive signals from the gonad. At E10.5, movie analysis has shown that germ cells remaining in the midline no longer migrate directionally towards the genital ridges, but instead rapidly fragment and disappear. Extragonadal germ cell tumors of infancy, one of the most common neonatal tumors, are thought to arise from midline germ cells that failed to die. This paper addresses the mechanism of midline germ cell death in the mouse. We show that at E10.5, the rate of apoptosis is nearly four-times higher in midline germ cells than those more laterally. Gene expression profiling of purified germ cells suggests this is caused by activation of the intrinsic apoptotic pathway. We then show that germ cell apoptosis in the midline is activated by down-regulation of Steel factor (kit ligand) expression in the midline between E9.5 and E10.5. This is confirmed by the fact that removal of the intrinsic pro-apoptotic protein Bax rescues the germ-cell apoptosis seen in Steel null embryos. Two interesting things are revealed by this: first, germ-cell proliferation does not take place in these embryos after E9.0; second, migration of germ cells is highly abnormal. These data show first that changing expression of Steel factor is required for normal midline germ cell death, and second, that Steel factor is required for normal proliferation and migration of germ cells.

Effect of sperm glutathione peroxidases 1 and 4 on embryo asymmetry and blastocyst quality in oocyte donation cycles

OBJECTIVE

To prospectively determine the impact of concrete components of the sperm oxidative glutathione stress system in terms of enzymatic activity and mitochondrial RNA (mRNA) expression on embryo quality and reproductive outcome. Human spermatozoa use the glutathione system to inactivate reactive oxygen metabolites, and there is a close correlation between some components of the glutathione system and male fertility. However, very few data are published regarding this system in sperm cells and its effect on fertilization ability and embryo development in human beings.

DESIGN

An oocyte-donation model, used to homogenize the female factor.

SETTING

University-affiliated private IVF setting.

PATIENT(S)

Semen samples from infertile males (n = 43) of couples undergoing oocyte-donation cycles (n = 43).

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Gene expression and activity of glutathione peroxidases (GPXs) 1 and 4, glutathione reductase, and intracellular glutathione (GSH) by fluorescent quantitative polymerase chain reaction and spectrophotometry, respectively.

RESULT(S)

Fertilization rate, pronuclear number, asymmetry, and pronuclear body distribution were not correlated with any sperm glutathione parameters that were considered. When day 3 embryo parameters were evaluated, only GPX4 mRNA expression in sperm cells was statistically significantly lower when asymmetric embryos were observed. Also, worst embryo development and morphology on day 5 was statistically significantly correlated with lower sperm GPX1 activity (101.07 vs. 258.8 IU/mg protein). Glutathione system analysis in fresh sperm was not statistically significantly different in patients achieving pregnancy compared with those who not, and we did not find any correlation with implantation rate.

CONCLUSION(S)

We have been able to correlate embryo morphology on day 3 with the sperm expression of GPX family members. The results indicate that sperm-derived mRNA may condition human embryo quality and persist even to blastocyst stage. The correlation of the sperm GPX family mRNA expression with embryo health appears quite promising for discovery of molecular causes of male infertility.

A new serine/threonine protein kinase, Omphk1, essential to ventral body wall formation

Here, we report a new serine/threonine protein kinase of the SNF1 subfamily Omphk1. Two Omphk homologues exist in each vertebrate species, and one homologue exists in Drosophila and Caenorhabditis elegans; the kinase domain is highly conserved among these homologues, and several domains are conserved among vertebrate Omphk. Omphk1 expression dynamically changes in the developing central nervous system, is found ubiquitously in epidermis, and is present uniquely in several other tissues. Its expression is also found in each tissue associated with the ventral body wall closure: the primary body wall composed of primitive ectoderm and each component of the secondary body wall. Concomitantly, its null mutant exhibits omphalocele with a failure in closure of the secondary body wall. There are no apparent gross morphological defects in brain, however, despite the unique Omphk1 expression in this tissue.

Myocardin is a direct transcriptional target of Mef2, Tead and Foxo proteins during cardiovascular development

Myocardin is a transcriptional co-activator of serum response factor (Srf), which is a key regulator of the expression of smooth and cardiac muscle genes. Consistent with its role in regulating cardiovascular development, myocardin is the earliest known marker specific to both the cardiac and smooth muscle lineages during embryogenesis. To understand how the expression of this early transcriptional regulator is initiated and maintained, we scanned 90 kb of genomic DNA encompassing the myocardin gene for cis-regulatory elements capable of directing myocardin transcription in cardiac and smooth muscle lineages in vivo. Here, we describe an enhancer that controls cardiovascular expression of the mouse myocardin gene during mouse embryogenesis and adulthood. Activity of this enhancer in the heart and vascular system requires the combined actions of the Mef2 and Foxo transcription factors. In addition, the Tead transcription factor is required specifically for enhancer activation in neural-crest-derived smooth muscle cells and dorsal aorta. Notably, myocardin also regulates its own enhancer, but in contrast to the majority of myocardin target genes, which are dependent on Srf, myocardin acts through Mef2 to control its enhancer. These findings reveal an Srf-independent mechanism for smooth and cardiac muscle-restricted transcription and provide insight into the regulatory mechanisms responsible for establishing the smooth and cardiac muscle phenotypes during development.

MRI analysis of angiogenesis during mouse embryo implantation

Uterine receptivity and embryo implantation depend on local induction of angiogenesis and vascular permeability. Poor uterine receptivity has been implicated in implantation failure; however, relatively little is known about the mechanism that underlies endometrial vascular hyperpermeability in implantation sites. Here we show that contrast-enhanced (CE)-MRI and fluorescence microscopy using biotin-BSA-GdDTPA allowed high-resolution detection and quantitative assessment of mouse embryo implantation sites as early as embryonic day 4.5 (E4.5), and subsequent vascular expansion at E5.5. Vessel permeability, but not blood volume, was significantly elevated in E4.5 implantation sites relative to nonimplanted uterus, showing that elevation of vascular permeability is a very early response preceding E4.5. A significantly increased blood volume was detected by MRI and fluorescence microscopy in implantation sites between E4.5 and E5.5. On the other hand, despite the increase in blood volume, implantation sites showed only a small nonsignificant further increase in vascular permeability during these 2 days, demonstrating the rapid dynamics of vascular remodeling during the early days of pregnancy. Functional imaging by MRI, as reported here, allows multiparametric measurement of angiogenesis during normal mouse implantation and would facilitate the application of MRI to evaluate involvement of the vasculature in mouse models of impaired implantation.