Home About us Contact
|
Home About us Contact | ||
|
|
||
Early Embryo Development (early + embryo_development)
Selected AbstractsEffects of Exogenous ACTH during Oestrus on Early Embryo Development and Oviductal Transport in the SowREPRODUCTION IN DOMESTIC ANIMALS, Issue 2 2007Y Brandt Contents This study was conducted to assess the effects of ACTH injections on the early development of embryos and their transportation to the uterus. Fifteen sows were monitored for ovulation using transrectal ultrasonography during the first two oestrous periods after weaning. The sows were randomly divided into a control group (C group, n = 8) and an ACTH-treated group (ACTH group, n = 7), and were all surgically fitted with intra-jugular catheters. From the onset of the second standing oestrus after weaning, the sows were injected (NaCl/synthetic ACTH) every 4 h. Blood samples were collected immediately before and 45 min after each injection. All sows were inseminated once 10,33 h before ovulation in their second oestrus after weaning. At 48 (n = 4) or 60 (n = 11) h after ovulation during their second oestrus, the sows were killed and the embryos retrieved from the oviduct and uterus. The embryos were counted and compared with the number of corpora lutea, cleavage rate was noted and, finally, the embryos were prepared for confocal laser scanning microscopy and transmission electron microscopy. There was no difference between the groups regarding cleavage rate, the cytoskeleton, or the number of active nucleoli. However, the ACTH group had significantly (p < 0.05) fewer ova/embryos retrieved (51%) than the C group (81%), and there was a tendency towards faster transportation to the uterus in the ACTH group, possibly because of high progesterone concentrations during treatment. To conclude, administration of ACTH every 4 h from onset of oestrus to 48 h caused significant loss of oocytes or embryos, and possibly faster transportation through the oviduct. [source] Medaka Oct4 is expressed during early embryo development, and in primordial germ cells and adult gonadsDEVELOPMENTAL DYNAMICS, Issue 2 2010Ana V. Sánchez-Sánchez Abstract Oct4 is a crucial transcription factor for controlling pluripotency in embryonic stem cells and the epiblast of mouse embryos. We have characterized the expression pattern of medaka (Oryzias latipes) Ol-Oct4 during embryonic development and in the adult gonads. Genomic analysis showed that Ol-Oct4 is the ortholog of zebrafish spg/pou2. However, their expression patterns are not the same, suggesting that Oct4 may play different roles in zebrafish and medaka. Using specific antibodies for the Ol-Oct4 protein, we showed that Ol-Oct4 is also expressed in primordial germ cells, in the spermatogonia (male germ stem cells), and during different stages of oocyte development. These results suggest that Ol-Oct4 plays a post-embryonic role in the maturing gonads and gametes. The Ol-Oct4 mRNA and protein expression patterns are similar to those of mammalian Oct4 and introduce medaka fish as a valid model for the functional and evolutionary study of pluripotency genes in vivo. Developmental Dynamics 239:672,679, 2010. © 2009 Wiley-Liss, Inc. [source] Microevolutionary support for a developmental hourglass: gene expression patterns shape sequence variation and divergence in DrosophilaEVOLUTION AND DEVELOPMENT, Issue 5 2008Tami Cruickshank SUMMARY A central goal of evolutionary developmental biology (Evo-Devo) is to synthesize comparative molecular developmental genetics and its description of the dynamic relationship between genotype and phenotype with the microevolutionary processes (mutation, random drift, and selection) of population genetics. To this end, we analyzed sequence variation of five gene classes that act sequentially to shape early embryo development in Drosophila: maternal, gap, pair-rule, segment polarity, and segment identity genes. We found two related patterns: (1) a microevolutionary pattern, wherein relative sequence variation within species is 2- to 3-fold higher for maternal-effect genes than for any other gene class; and, (2) a macroevolutionary pattern, wherein the relative sequence divergence among species for maternal-effect genes is 2- to 4-fold greater than for any other gene class. Both patterns are qualitatively and quantitatively consistent with the predictions of microevolutionary theory. Our findings connect within-species genetic variation to between-species divergence and shed light on the controversy over the existence of a "developmental hourglass," where mid-embryonic stages are more evolutionarily constrained than either earlier or later stages. Because maternal-effect genes experience relaxed selective constraint relative to zygotic-effect genes, they explore a wider mutational and phenotypic space. As a result, early acting maternal-effect genes diverge more widely across taxa and thereby broaden the base of the developmental hourglass. In contrast, later acting zygotic genes are relatively more constrained and limited in their diversification across taxa, narrowing the waist of the developmental hourglass. This pattern is obscured by genes with both maternal and zygotic expression, which experience the strongest evolutionary constraint. [source] Transcription profile in mouse four-cell, morula, and blastocyst: Genes implicated in compaction and blastocoel formationMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 2 2007Xiang-Shun Cui Abstract To gain insight into early embryo development, we utilized microarray technology to compare gene expression profiles in four-cell (4C), morula (MO), and blastocyst (BL) stage embryos. Differences in spot intensities were normalized, and grouped by using Avadis Prophetic software platform (version 3.3, Strand Genomics Ltd.) and categories were based on the PANTHER and gene ontology (GO) classification system. This technique identified 622 of 7,927 genes as being more highly expressed in MO when compared to 4C (P,<,0.05); similarly, we identified 654 of 9,299 genes as being more highly expressed in BL than in MO (P,<,0.05). Upregulation of genes for cytoskeletal, cell adhesion, and cell junction proteins were identified in the MO as compared to the 4C stage embryos, this means they could be involved in the cell compaction necessary for the development to the MO. Genes thought to be involved in ion channels, membrane traffic, transfer/carrier proteins, and lipid metabolism were also identified as being expressed at a higher level in the BL stage embryos than in the MO. Real-time RT-PCR was performed to confirm differential expression of selected genes. The identification of the genes being expressed in here will provide insight into the complex gene regulatory networks effecting compaction and blastocoel formation. Mol. Reprod. Dev. © 2006 Wiley-Liss, Inc. [source] Surface mapping of binding of oviductin to the plasma membrane of golden hamster spermatozoa during in vitro capacitation and acrosome reactionMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 6 2006Frederick W.K. Kan Abstract Oviductins are high-molecular-weight glycoproteins synthesized and secreted by nonciliated oviductal epithelial cells and have been shown to play a role in fertilization and early embryo development. The present study was carried out to examine the in vitro binding capacity of hamster oviductin to homologous sperm and to determine the sites of its localization in untreated, capacitated, and acrosome-reacted spermatozoa. Freshly prepared epididymal and capacitated sperm as well as acrosome-reacted sperm were incubated with oviductal fluid prepared from isolated hamster oviducts, fixed and then probed with a monoclonal antibody against hamster oviductin. Results obtained with pre-embedding immunolabeling experiments revealed binding of oviductin to the acrosomal cap and the apical aspect of the postacrosomal region. Immunolabeling of both regions appeared to be more intense in capacitated spermatozoa. Acrosome-reacted sperm showed an immunoreaction of moderate intensity over the postacrosomal region. The plasma membrane overlying the equatorial segment also exhibited a weak labeling. Quantitative analysis obtained with the surface replica technique indicated that oviductin had a higher binding affinity for the acrosomal cap than the postacrosomal region and that the binding of oviductin to the latter plasma membrane domain was enhanced during capacitation. Binding of oviductin to the postacrosomal region, however, was attenuated after acrosome reaction. Immunolabeling for oviductin was found to be the weakest over the equatorial segment regardless of the experimental conditions. The binding of hamster oviductin to specific membrane domains of the homologous sperm and the changes in its distribution during capacitation and acrosome reaction may be important for the function of hamster oviductin preceding and during fertilization. Mol. Reprod. Dev. © 2006 Wiley-Liss, Inc. [source] Cytoskeletal Changes in Oocytes and Early Embryos During in vitro Fertilization Process in MiceANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 1 2010E. Gumus Summary The cytoskeleton plays crucial roles in the development and fertilization of germ cells and in the early embryo development. The growth, maturation and fertilization of oocytes require an active movement and a correct localization of cellular organelles. This is performed by the re-organization of microtubules and actin filaments. Therefore, the aim of the present study was to determine the changes in cytoskeleton during in vitro fertilization process using appropriate immunofluorescence techniques. While the chromatin content was found to be scattered throughout the nucleus during the oocyte maturation period, it was seen only around nucleolus following the completion of the maturation. Microtubules, during oocyte maturation, were regularly distributed throughout the ooplasm which was then localized in the subcortical region of oocytes. Similarly microfilaments were scattered throughout the ooplasm during the oocyte maturation period whereas they were seen in the subcortical region around the polar body and above the meiotic spindle throughout the late developmental stages. In conclusion, those changes occurred in microtubules and microfilaments might be closely related to the re-organization of the genetic material during the oocyte maturation and early embryo development. [source] Analysis of segregation distortion and association of the bovine FGF2 with fertilization rate and early embryonic survivalANIMAL GENETICS, Issue 5 2009X. Wang Summary Fibroblast growth factor 2 (FGF2) plays an important role in fertility and early embryo development. The objectives of this study were to test the association of FGF2 polymorphisms with fertilization success in cattle using an in vitro fertilization experimental system and to investigate the mechanisms leading to the presence of rare alleles of FGF2 in the Holstein population. A total of 7502 fertilizations were performed and a total of 5049 embryos were produced to collect fertilization and embryo survival records. A total of 444 ovaries, from which oocytes were aspirated and fertilized, were genotyped for two single nucleotide polymorphisms (SNPs) previously identified in FGF2 (g.23G>T and g.11646A>G). Frequency of the TT genotype of the g.23G>T SNP was low in the ovary population (5.4%) and in a different Holstein cattle population (6.6%) examined in this study. Single SNP analysis showed that both SNPs were associated with early embryonic survival rate. Two-way interaction analysis revealed significant association of epistatic interaction between the SNPs with fertilization rate. To test whether or not low frequency of allele T for the g.23G>T SNP in the population is a result of a fertilization failure of T oocytes, semen from six GG bulls was used to fertilize a total of 458 oocytes obtained from 19 GT ovaries. A significant segregation distortion was observed for 169 embryos genotyped for the g.23G>T SNP. We conclude that oocytes carrying the T allele show a reduced fertilization rate and that segregation distortion leads to rarity of the TT genotype in the population. [source] Analysis of the oviductal glycoprotein 1 polymorphisms and their effects on components of litter size in rabbitsANIMAL GENETICS, Issue 5 2009M. Merchán Summary The objective of this work was to study the effect of the oviductal glycoprotein 1 (OVGP1) genotype and mRNA expression on litter size and other fertility measures, as OVGP1 has positive effects on fertilization and early embryo development. We have analysed an F2 cross of two lines of rabbits divergently selected for uterine capacity. The OVGP1 mRNA expression was analysed in both lines, but no differences were observed between them. The promoter region and mRNA were sequenced in the F0 generation, and 17 polymorphic sites were found to co-segregate in three haplotypes (A, B and C). An association study was performed between several reproductive traits and a triallelic microsatellite identified in the promoter region as well as a non-synonymous SNP located in exon 11 [g.12944C>G (p.Arg468Gly)]. The alleles g.12944G and g.325(GT)14T(G)5 of the B haplotype have a positive effect on the total number of kits born, number born alive, number of implanted embryos and foetal and prenatal embryo survival. [source] | ||||||||||