957 resultados para Ascidian Embryos
Resumo:
Cells of the mononuclear phagocyte lineage possess receptors for macrophage colony-stimulating factor (CSF-1) encoded by the c-fms protooncogene and respond to CSF-1 with increased survival, growth, differentiation, and reversible changes in function. The c-fms gene is itself a macrophage differentiation marker. In whole mount analyses of mRNA expression in embryos, c-fms is expressed at very high levels on placental trophoblasts. It is detectable on individual cells in the yolk sac around 8.5 to 9 days postcoitus, appears on isolated cells in the head of the embryo around 9.5 dpc, and appears on numerous cells throughout the embryo by day 10.5. The extent of c-fms expression is much greater than for other macrophage-specific genes including lysozyme and a macrophage-specific protein tyrosine phosphatase. Our studies of the cis-acting elements of the c-fms promoter have indicated a key role for collaboration between the macrophage-specific transcription factor, Pu.1, which functions in determining the site of transcription initiation, and other members of the Ets transcription factor family. This is emerging as a common pattern in macrophage-specific promoters. We have shown that two PU box elements alone can function as a macrophage-specific promoter. The activity of both the artifical promoter and the c-fms promoter is activated synergistically by coexpression of Pu.1 and another Ets factor, c-Ets-2. A 3.5kb c-fms exon 2 promoter (but not the 300bp proximal promoter) is also active in a wide diversity of tumor cell lines. The interesting exception is the melanoma cell line K1735, in which the promoter is completely shut down and expression of c-fms causes growth arrest and cell death. The activity of the exon 2 promoter in these nonmacrophages is at least as serum responsive as the classic serum-responsive promoter of the c-fos gene. It is further inducible in nonmacrophages by coexpression of the c-fms product. Unlike other CSF-1/c-fms-responsive promoters, the c-fms promoter is not responsive to activated Ras even when c-Ets-2 is coexpressed. In most lines, production of full length c-fms is prevented by a downstream intronic terminator, but in Lewis lung carcinoma, read-through does occur, and expression of both c-fms and other macrophage-specific genes such as lysozyme and urokinase becomes detectable in conditions of serum deprivation. (C) 1997 Wiley-Liss, Inc.
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Objective: To evaluate influences of vitrification and warming of metaphase II (MII) mouse oocytes on survival, spindle dynamics. spindle morphology, and chromatin alignment on metaphase plates. Design: Experimental animal Study. Setting: University animal laboratory. Animal(s): Eight-week-old B6D2F1 mice. Intervention(s): Denuded MII oocytes were used fresh (control), exposed to vitrification/warming solutions (Sol Expos), or vitrified and warmed (Vitr). Main Outcome Measure(s): Oocyte recovery and survival after warming and the influence of solution exposure and cryopreservation on spindle dynamics and chromatin alignment. Result(s): Cryopreservation of two or 10 oocytes per straw resulted in recovery (100% +/- 0% and 95% +/- 4%, respectively; mean SE) and survival (95% 2% and 98% 2%, respectively). Immediately after warming (Vitr), significantly fewer oocytes assessed with immunocytochemistry contained spindles, compared with control and Sol Expos. When oocytes were placed into a 3 degrees 7C environment for 2 hours after exposure or warming, the ability to recognize spindles by immunocytochemistry was not significantly different between groups. Using live-cell time-lapse imaging with LC-Polscope, similar time-dependent spindle formation dynamics were observed. At 2 hours after collection or treatment, spindle morphology and length were not significantly different between the groups, nor was the incidence of aberrant alignment of chromatin on metaphase plates. Conclusion(s): Immediately after warming of vitrified MII oocytes, beta-tubulin is depolymerized and chromatin remains condensed on the metaphase plate. Within a 2-hour period, beta-tubulin repolymerizes, forming morphologically normal metaphase spindles with properly aligned chromatin.
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Contents Sex pre-selection of bovine offsprings has commercial relevance for cattle breeders and several methods have been used for embryo sex determination. Polymerase chain reaction (PCR) has proven to be a reliable procedure for accomplishing embryo sexing. To date, most of the PCR-specific primers are derived from the few single-copy Y-chromosome-specific gene sequences already identified in bovines. Their detection demands higher amounts of embryonic genomic material or a nested amplification reaction. In order to circumvent this, limitation we searched for new male-specific sequences potentially useful in embryo sexing using random amplified polymorphic DNA (RAPD) analysis. Random amplified polymorphic DNA (RAPD) assay reproducibility problems can be overcome by its conversion into Sequence Characterized Amplified Region (SCAR) markers. In this work, we describe the identification of two bovine male-specific markers (OPC16(323) and OPF10(1168)) by means of RAPD. These markers were successfully converted into SCARs (OPC16(726) and OPF10(984)) using two pairs of specific primers.Furthermore, inverse PCR (iPCR) methodology was successfully applied to elongate OPC16(323) marker in 159% (from 323 to 837 bp). Both markers are shown to be highly conserved (similarity >= 95%) among bovine zebu and taurine cattle; OPC16(323) is also highly similar to a bubaline Y-chromosome-specific sequence. The primers derived from the two Y-chromosome-specific conserved sequences described in this article showed 100% accuracy when used for identifying male and female bovine genomic DNA, thereby proving their potential usefulness for bovine embryo sexing.
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Introduction. The hippocampal formation is a specific structure in the brain where neurogenesis occurs throughout adulthood and in which the neuronal cell loss causes various demential states. The main goal of this study was to verify whether fetal neural progenitor cells (NPCs) from transgenic rats expressing green fluorescent protein (GFP) retain the ability to differentiate into neuronal cells and to integrate into the hippocampal circuitry after transplantation. Methods. NPCs were isolated from E14 (gestational age: 14 days postconception) transgenic-Lewis and wild-type Sprague-Dawley rat embryos. Wild-type and transgenic cells were expanded and induced to differentiate into a neuronal lineage in vitro. Immunocytochemical and electrophysiological analysis were performed in both groups. GFP-expressing cells were implanted into the hippocampus and recorded electrophysiologically 3 months thereafter. Immunohistochemical analysis confirmed neuronal differentiation, and the yield of neuronal cells was determined stereologically. Results. NPCs derived from wild-type and transgenic animals are similar regarding their ability to generate neuronal cells in vitro. Neuronal maturity was confirmed by immunocytochemistry and electrophysiology, with demonstration of voltage-gated ionic currents, firing activity, and spontaneous synaptic currents. GFP-NPCs were also able to differentiate into mature neurons after implantation into the hippocampus, where they formed functional synaptic contacts. Conclusions. GFP-transgenic cells represent an important tool in transplantation studies. Herein, we demonstrate their ability to generate functional neurons both in vitro and in vivo conditions. Neurons derived from fetal NPCs were able to integrate into the normal hippocampal circuitry. The high yield of mature neurons generated render these cells important candidates for restorative approaches based on cell therapy.
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Objective: To compare cryopreservation of mature human oocytes with slow-rate freezing and vitrification and determine which is most efficient at establishing a pregnancy. Design: Prospective randomized. Setting: Academically affiliated, private fertility center. Patient(s): Consenting patients with concerns about embryo cryopreservation and more than nine mature oocytes at retrieval were randomized to slow-rate freezing or vitrification of supernumerary (more than nine) oocytes. Intervention(s): Oocytes were frozen or vitrified, and upon request oocytes were thawed or warmed, respectively. Main Outcome Measure(s): Oocyte survival, fertilization, embryo development, and clinical pregnancy. Result(s): Patient use has resulted in 30 thaws and 48 warmings. Women`s age at time of cryopreservation was similar. Oocyte survival was significantly higher following vitrification/warming (81%) compared with freezing/thawing (67%). Fertilization was more successful in oocytes vitrified/warmed compared with frozen/thawed. Fertilized oocytes from vitrification/warming had significantly better cleavage rates (84%) compared with freezing/thawing (71%) and resulted in embryos with significantly better morphology. Although similar numbers of embryos were transferred, embryos resulting from vitrified oocytes had significantly enhanced clinical (38%) pregnancy rates compared with embryos resulting from frozen oocyte (13%). Miscarriage and/or spontaneous abortion rates were similar. Conclusion(s): Our results suggest that vitrification/warming is currently the most efficient means of oocyte cryopreservation in relation to subsequent success in establishing pregnancy. (Fertil Steril (R) 2010; 94: 2088-95. (C) 2010 by American Society for Reproductive Medicine.)
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Genomic imprinting alterations have been shown to be associated with assisted reproductive technologies (ARTs) in animals. At present, data obtained in humans are inconclusive; however, some epidemiological studies have demonstrated an increased incidence of imprinting disorders in children conceived by ARTs. In the present study, we focused on the effect of ARTs [IVF and intracytoplasmic sperm injection (ICSI)] on the epigenetic reprogramming of the maternally methylated imprinting control region KvDMR1 in clinically normal children. Qualitative and quantitative methylation at KvDMR1 were assessed by the methylation-specific PCR approach and by the methylation-sensitive enzymatic digestion associated with real-time PCR method, respectively. DNA was obtained from peripheral blood of 12/18 and umbilical cord blood and placenta of 6/18 children conceived by IVF or ICSI. The methylation patterns observed in this group were compared with the patterns observed in 30 clinically normal naturally conceived children (negative controls) and in 3 naturally conceived Beckwith-Wiedemann syndrome patients (positive controls). Hypomethylation at KvDMR1 was observed in 3/18 clinically normal children conceived by ARTs (2 conceived by IVF and 1 by ICSI). A discordant methylation pattern was observed in the three corresponding dizygotic twins. Our findings corroborate the hypothesis of vulnerability of maternal imprinting to ARTs. Furthermore, the discordant methylation at KvDMR1 observed between dizygotic twins could be consequent to one of the following possibilities: (i) a differential vulnerability of maternal imprints among different embryos; or (ii) epimutations that occurred during gametogenesis resulting in the production of oocytes without the correct primary imprint at KvDMR1.
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Our purpose was to retrospectively compare controlled ovarian stimulation(COH) in IVF cycles with administration of hCG on the day of menses (D1-hCG) with women not receiving hCG at day 1 of menses (Control). Data on maternal age, endocrine profile, amount of rFSH required, embryo characteristics, implantation and pregnancy rates were recorded for comparison between D1-hCG (n = 36) and Control (n = 64). Dose of rFSH required to accomplish COH was significantly lower in D1-hCG. Following ICSI, more top-quality embryos were available for transfer per patient in the D1-hCG and biochemical pregnancy rates per transfer were significantly higher in the D1-hCG. Significantly higher implantation and on-going pregnancy rates per embryo transfer were observed in D1-hCG (64%) compared to Control (41%). Administration of D1-hCG prior to COH reduces rFSH use and enhances oocyte developmental competence to obtain top quality embryos, and improves implantation and on-going pregnancy rates. At present it is not clear if the benefit is related to producing an embryo that more likely to implant or a more receptive uterus, or merely fortuitous and related to the relatively small power of the study.
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Resveratrol is a stilbene compound found in grapes and other sources. In this study we examined the effects of trans-resveratrol (4.38-438 mu M/implant) in the vasculogenesis of yolk-sac membranes and its capacity to improve chick embryo growth. High concentrations of the stilbene (43.8-438 mu M) significantly inhibited early vessel formation, decreasing the percentage vitelline vessels of 3.5-day embryos by 50% compared to the control. In addition, basic fibroblast growth factor-stimulated vasculogenesis (140% of vessels as compared to control) was partially reversed by t-resveratrol (35% of inhibition) and treatments with cyclooxygenase inhibitors (acetylsalicylic acid and indomethacin) as well a protein-kinase C (PKC) activator (phorbol-12,13-dibutyrate) decreased the vessel number to 60%, 50%, and 44%, respectively. Treatments with t-resveratrol (4.38-43.8 mu M/implant) significantly increased the body length of embryos incubated in vitro uncoupled from any impairment in the body shape or detectable embryotoxic effect. We suggest that the antivasculogenic activity and the enhancement in embryonic growth promoted by non acute treatments with t-resveratrol were, at least in part, due to PKC inhibition. We suggest that t-resveratrol can be usable not only as a reliable functional nutriment, but also is useful for the development of prophylactic and/or therapeutic agents for treatment of angiogenic-degenerative diseases.
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Objective: To assess the impact of the mean oocyte diameter (MOD) on occurrence of fertilization and embryo quality in assisted reproduction cycles. Design: Prospective observational study. Setting: Sector of Human Reproduction of the University Hospital, Faculty of Medicine of Ribeirao Preto, University of Sao Paulo (HCFMRP-USP). Patient(s): Thirty-five women undergoing intracytoplasmic sperm injection (ICSI) at the University Hospital of Ribeirao Preto from May to October 2007. Intervention(s): MOD assessment. Main Outcome Measure(s): Occurrence of fertilization and qualitative embryo classification on 2nd and 3rd day after ICSI. Result(s): We divided 160 metaphase II oocytes according to MOD into groups A (MOD below the 25th percentile), B (MOD between 25th and 75th percentile), and C (MOD above the 75th percentile). There was no statistically significant association between MOD and the occurrence of fertilization or the qualitative embryo classification on days 2 and 3. There was no statistically significant difference between groups regarding number of cells or the qualitative embryo classification on days 2 and 3. Conclusion(s): The MOD of mature oocytes does not seem to be related to the occurrence of fertilization or to the developmental quality of human embryos on days 2 and 3 after ICSI. (Fertil Steril(R) 2010;93:621-5. (C)2010 by American Society for Reproductive Medicine.)
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In vitro culture conditions affect both the maternal and embryonic expression of genes and is likely to alter both oocyte and embryo developmental competence. The search for better and less variable culture conditions simulating those in vivo has led to the development of defined culture media, with lower impact on the molecular reprogramming of oocytes and embryos. We evaluated embryo development and relative abundance (RA) of Hsp-70 and Bax transcripts in bovine blastocysts produced from oocytes matured in a chemically defined IVM system with synthetic polymers. Immature cumulus oocyte complexes (COCs) were matured for 22-24 h in alpha-MEM supplemented with IGF-1, insulin, 0.1% polyvinyl alcohol (PVA), or 0.1% polyvinylpyrrolidone (PVP), but without FSH or LH. The control group consisted of COCs matured it, TCM plus FSH and 10% estrous cow serum. After fertilization. presumptive zygotes were co-cultured with cumulus cells until 224 h post-insemination. Total RNA was isolated from embryo pools, reverse transcribed into cDNA, and subjected to transcript analysis by real-time PCR. Cleavage rate was higher (P < 0.05) for the control group (68.3%) than for the PVA (54.4%) and PVP-40 (58.3%) groups. Nevertheless. there was no difference among the PVA, PVP-40 and control groups in blastocyst or hatching rates. similarly, no difference in relative abundance of Hsp-70 and Bax transcripts was detected in comparison to the control group. We inferred that bovine oocytes can be matured in serum- and gonadotrophin-free medium supplemented with PVA or PVP, enriched with IGF-I and insulin, without altering post-cleavage development and relative abundance of some genes associated with stress and apoptosis. (C) 2009 Elsevier Inc. All rights reserved.
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Objectives: To evaluate the influence of the morphology of the first polar body (PB) on intracytoplasmic sperm injection (ICSI) outcomes. Methods: The morphology of the first PB was assessed in 3177 metaphase 11 oocytes and classified as: intact and normal size, fragmented, or enlarged size. The rates of fertilization, cleavage, and embryo quality were evaluated on day 2. Results: The rates of fertilization, cleavage, and formation of good quality embryos resulting from the insemination of oocytes with an enlarged first PB (20.7%, 18.7%, and 5.0%, respectively) were significantly lower than those for oocytes with an intact first PB of normal size (70.8%, 62.5%, and 19%, respectively) or a fragmented first PB (69.7%, 60.5%, and 17.1%, respectively). Rates did not differ significantly between oocytes with an intact first PB of normal size and oocytes with a fragmented first PB (P>0.05). Conclusions: The presence of an enlarged PB is related to poorer rates of fertilization, cleavage, and top quality embryos. However, identification of first PB fragmentation does not seem to interfere with ICSI outcomes. (C) 2008 International Federation ofGynecology and Obstetrics. Published by Elsevier Ireland Ltd. All rights reserved.
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Objective: To compare oocyte maturation, fertilization and cleavage rates, and embryonic developmental quality after culture of human immature oocytes from polycystic ovary syndrome (PCOS) patients in human tubal fluid (HTF) or tissue culture medium (TCM) 199. Design: Prospective, randomized, controlled trial. Setting: University hospital. Patient(s): Thirteen women undergoing 23 in vitro maturation cycles, from whom 119 oocytes were retrieved. Intervention(s): Cumulus-enclosed germinal vesicle-stage oocytes matured in TCM-199-supplemented or HTF-supplemented media. Main Outcome Measure(s): Oocyte maturation and fertilization rates, embryonic developmental quality. Result(s): Significant differences were observed between TCM 199 and HTF regarding maturation rate (82% vs. 56.9%), fertilization rate (70% vs. 39.4%), and embryo quality (81.3% vs. 41.7%). Conclusion(S): Human tubal fluid medium, although widely used for embryo fertilization and maintenance in IVF techniques, is not,in appropriate medium for the maturation of oocytes obtained from PCOS patients in nonstimulated cycles. (Fertil Steril(R) 2009;91:509-13. (C)2009 by American Society for Reproductive Medicine.)
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The aim of this study was to compare the crown-rump length (CRL) and the fetal head and trunk (HT) volume between singletons and twins conceived after in vitro fertilization. Thirty pregnant patients submitted to embryo transfer were enrolled in this research. Ten conceived twins (20 dichorionic fetuses) while other 20 conceived singletons. The gestational age was calculated by adding 14 d to the number of days between the oocyte retrieval and the scheduled ultrasound. Three-dimensional ultrasound scans were performed weekly from 73 d (10 wk and 3 d) to 101 d (14 wk and 3 d) of gestational age. HT volume was assessed by VOCAL using 15 degrees step rotation on the manual mode. The measurement of CRL was performed by using the longitudinal plane of the fetus in the multiplanar view. The CRL and HT volume weekly relative increase were evaluated to compare the growth between singletons and twins. No significant difference was identified, in any analyzed week, when comparing the mean of CRL and HT volume between singletons and twins. Additionally, no significant difference between singletons and twins was noticed when comparing the weekly relative increase, both for CRL and HT volume. However, the weekly relative increase was significantly higher for HT volume than for CRL in every week studied for both singletons and twins. The total relative increase observed between 73 and 101 d was much higher for HT volume than for CRL: 679 +/- 39% versus 138 +/- 18% in singletons and 689 +/- 58% versus 139 +/- 21% in twins (HT volume and CRL, respectively), suggesting that HT volume could more accurately determine the gestational age.
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The sciarid DNA puff C4 BhC4-1 gene is amplified and transcribed in salivary glands at the end of the larval stage. In transgenic Drosophila, the BhC4-1 promoter drives transcription in prepupal salivary glands and in the ring gland of late embryos. A bioinformatics analysis has identified 162 sequences similar to distinct regions of the BhC4-1 proximal promoter, which are predominantly located either in 5` or 3` regions or introns in the Drosophila melanogaster genome. A significant number of the identified sequences are found in the regulatory regions of Drosophila genes that are expressed in the salivary gland. Functional assays in Drosophila reveal that the BhC4-1 proximal promoter contains both a 129 bp (-186/-58) salivary gland enhancer and a 67 bp (-253/-187) ring gland enhancer that drive tissue specific patterns of developmentally regulated gene expression, irrespective of their orientation.
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BACKGROUND: Comparative genomic hybridization (CGH) is a valuable alternative to fluorescence in situ hybridization (FISH) for preimplantation genetic screening (PGS) because it allows full karyotype analysis. However, this approach requires the cryopreservation of biopsied embryos until results are available. The aim of this study is to reduce the hybridization period of CGH, in order to make this short-CGH technique suitable for PGS of Day-3 embryos, avoiding the cryopreservation step. METHODS: Thirty-two fibroblasts from six aneuploid cell lines (Coriell) and 48 blastomeres from 10 Day-4 embryos, discarded after PGS by FISH with 9 probes (9-chr-FISH), were analysed by short-CGH. A reanalysis by the standard 72 h-CGH and FISH using telomeric probes was performed when no concordant results between short-CGH and FISH diagnosis were observed. The short-CGH was subsequently applied in a clinical case of advanced maternal age. RESULTS: In 100% of the fibroblasts analysed, the characteristic aneuploidies of each cell line were detected by short-CGH. The results of the 48 blastomeres screened by short-CGH were supported by both 72 h-CGH results and FISH reanalysis. The chromosomes most frequently involved in aneuploidy were 22 and 16, but aneuploidies for the other chromosomes, excepting 1, 10 and 13, were also detected. Forty-one of the 94 aneuploid events observed (43.6%) corresponded to chromosomes which are not analysed by 9-chr-FISH. CONCLUSIONS: We have performed a preliminary validation of the short-CGH technique, including one clinical case, suggesting this approach may be applied to Day-3 aneuploidy analysis, thereby avoiding embryo cryopreservation and perhaps helping to improve implantation rate after PGS.