How the embryonic body axis is generated is a fundamental question in developmental biology. The molecular mechanisms involved in this process have been the subject of intensive studies using traditional model organisms during the last few decades, and the results have provided crucial information for understanding the formation of animal body plans. In particular, studies exploring the molecular nature of Spemann's organizer have revealed the intricate interactions underlying several signaling pathways (namely the Wnt/β-catenin, Nodal and Bmp pathways) that pattern the dorsoventral (DV) axis in vertebrate embryos. Furthermore, recent comparative studies have shown that many of these signaling interactions are also employed in other non-vertebrate model organisms for their early embryonic axis patterning. These results suggest that there is deep homology in DV patterning mechanisms among bilaterian animals and that these mechanisms may be traced back to the common ancestor of cnidarians and bilaterians. However, the mechanism by which the DV axis became inverted in the chordate lineage relative to the DV axis in other bilaterian animals remains unclear. Cephalochordata (i.e., amphioxus) represent a basal chordate group which occupies a key phylogenetic position for explorations of the origin of the chordate body plan. In this review, we summarize what is currently known regarding the developmental mechanisms that establish the DV axis in amphioxus embryos. By comparing this to what is known in vertebrates, we can start to hypothesize about the ancestral DV patterning mechanisms in chordates and discuss their possible evolutionary origins.

• MeSH
• cytoskelet metabolismus   MeSH
• embryo nesavčí embryologie   metabolismus   MeSH
• kopinatci embryologie   genetika   metabolismus   MeSH
• rozvržení tělního plánu genetika   MeSH
• signální transdukce genetika   MeSH
• vývojová regulace genové exprese * MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH

Formation of a dorsoventral axis is a key event in the early development of most animal embryos. It is well established that bone morphogenetic proteins (Bmps) and Wnts are key mediators of dorsoventral patterning in vertebrates. In the cephalochordate amphioxus, genes encoding Bmps and transcription factors downstream of Bmp signaling such as Vent are expressed in patterns reminiscent of those of their vertebrate orthologues. However, the key question is whether the conservation of expression patterns of network constituents implies conservation of functional network interactions, and if so, how an increased functional complexity can evolve. Using heterologous systems, namely by reporter gene assays in mammalian cell lines and by transgenesis in medaka fish, we have compared the gene regulatory network implicated in dorsoventral patterning of the basal chordate amphioxus and vertebrates. We found that Bmp but not canonical Wnt signaling regulates promoters of genes encoding homeodomain proteins AmphiVent1 and AmphiVent2. Furthermore, AmphiVent1 and AmphiVent2 promoters appear to be correctly regulated in the context of a vertebrate embryo. Finally, we show that AmphiVent1 is able to directly repress promoters of AmphiGoosecoid and AmphiChordin genes. Repression of genes encoding dorsal-specific signaling molecule Chordin and transcription factor Goosecoid by Xenopus and zebrafish Vent genes represents a key regulatory interaction during vertebrate axis formation. Our data indicate high evolutionary conservation of a core Bmp-triggered gene regulatory network for dorsoventral patterning in chordates and suggest that co-option of the canonical Wnt signaling pathway for dorsoventral patterning in vertebrates represents one of the innovations through which an increased morphological complexity of vertebrate embryo is achieved.

• MeSH
• 5' nepřekládaná oblast MeSH
• Chordata genetika   MeSH
• dánio pruhované embryologie   genetika   MeSH
• embryo nesavčí MeSH
• fylogeneze MeSH
• genetická variace genetika   fyziologie   MeSH
• genové regulační sítě MeSH
• homeodoménové proteiny genetika   MeSH
• konzervovaná sekvence genetika   MeSH
• kultivované buňky MeSH
• lidé MeSH
• molekulární evoluce MeSH
• molekulární sekvence - údaje MeSH
• Oryzias embryologie   genetika   MeSH
• protein goosecoid genetika   MeSH
• rozvržení tělního plánu genetika   MeSH
• sekvence aminokyselin MeSH
• sekvence nukleotidů MeSH
• sekvenční homologie aminokyselin MeSH
• vývojová regulace genové exprese MeSH
• Xenopus laevis embryologie   genetika   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

In mouse, the oocyte-to-embryo transition entails converting a highly differentiated oocyte to totipotent blastomeres. This transition is driven by degradation of maternal mRNAs, which results in loss of oocyte identity, and reprogramming of gene expression during the course of zygotic gene activation, which occurs primarily during the two-cell stage and confers blastomere totipotency. Full-grown oocytes are transcriptionally quiescent and mRNAs are remarkably stable in oocytes due to the RNA-binding protein MSY2, which stabilizes mRNAs, and low activity of the 5' and 3' RNA degradation machinery. Oocyte maturation initiates a transition from mRNA stability to instability due to phosphorylation of MSY2, which makes mRNAs more susceptible to the RNA degradation machinery, and recruitment of dormant maternal mRNAs that encode for critical components of the 5' and 3' RNA degradation machinery. Small RNAs (miRNA, siRNA, and piRNA) play little, if any, role in mRNA degradation that occurs during maturation. Many mRNAs are totally degraded but a substantial fraction is only partially degraded, their degradation completed by the end of the two-cell stage. Genome activation initiates during the one-cell stage, is promiscuous, low level, and genome wide (and includes both inter- and intragenic regions) and produces transcripts that are inefficiently spliced and polyadenylated. The major wave of genome activation in two-cell embryos involves expression of thousands of new genes. This unique pattern of gene expression is the product of maternal mRNAs recruited during maturation that encode for transcription factors and chromatin remodelers, as well as dramatic changes in chromatin structure due to incorporation of histone variants and modified histones.

• MeSH
• embryo savčí metabolismus   MeSH
• genom MeSH
• myši MeSH
• oocyty metabolismus   MeSH
• stabilita RNA genetika   MeSH
• transkriptom genetika   MeSH
• vývojová regulace genové exprese MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Research Support, N.I.H., Extramural MeSH

Cieľ: Posúdenie vývojových schopností ľudských embryí na základe časového priebehu prvých bunkových delení. Typ štúdie: Retrospektívna analýza. Názov a sídlo pracoviska: Prague Fertility Centre a Ústav pro péči o matku a dítě, CAR, Praha. Metodika: Vývoj embryí z IVF programu bol monitorovaný za použitia time-lapse (PrimoVision, Cryo- Innovation, 1 obr./10 min, intermittent white-light illumination) v štandardných kultivačných podmienkach (37,0 °C , 5 % CO2 vo vlhkom vzduchu). Získané záznamy boli uschované pre účely retrospektívnej analýzy. Priebeh 1. mitotického delenia embryí sme sledovali za pomoci intravitálneho farbenia chromatínu fluorescenčným farbivom (Hoechst 33342) a deliace vretienko sme vizualizovali pomocou polarizačnej mikroskopie (Oosight, Research Instruments). Analyzovali sme záznamy 180 embryí, ktorých vývoj jednoznačne viedol k vzniku klinického tehotenstva (dg. FHB, fetal heart beat). Časový priebeh prvých štyroch interfáz (IP) a synchrónia delenia dcérskych buniek (ID, interval delenia) boli manuálne zaznamenané a vyhodnotené u týchto embryí. IP1(prvá interfáza) bola definovaná ako časový interval od oplodnenia do syngamie. IP2 od 2bunkového do 3bunkového embrya, IP3 interval medzi 3–5bunkovým štádiom a IP4 bol časový interval medzi 5bunkovým a 9bunkovým štádiom. Interval delenia sesterských buniek v danej mitóze (tj. vyjadrenie synchrónnosti delenia) bol zaznamenaný ako ID1: interval od syngamie do 2bunkového štádia, ID2: interval od 3 do 4 buniek, ID3: od 5 do 8 buniek a ID4: od 9bunkového do 16bunkového embrya. Výsledky: U 180 embryí, ktorých vývoj viedol k vzniku klinickej gravidity, sme namerali tieto dĺžky interfáz: IP1 (prvá interfáza) trvala: 20–26 hod., IP2: 10–12 hod., IP3: 14–16 hod. a IP4: 20–26 hod. Intervaly delenia sesterských buniek v danej mitóze boli u týchto embryí nasledovné: ID1: 120–210 min., ID2: 20–60 min., ID3: 120–240 min. a ID4: 230–360 min. Záver: Vitálne embryá sa delia vo veľmi podobných časových intervaloch, ktoré je možné odmerať a vytvoriť referenčné hodnoty. Neinvazívne meranie dĺžky bunkového cyklu v prvých dňoch embryonálneho vývoja je možné použiť ako objektívne merateľný ukazovateľ životaschopnosti ľudských embryí.

Objective: The evaluation of the developmental abilities of human embryos according to the timing of their early mitotic cleavages. Design: Retrospective study. Setting: Prague Fertility Centre and Institute for Care of Mother and Child, CAR, Prague. Methods: The embryos obtained in IVF program were used for further observations and subjected to automated time-lapse monitoring (PrimoVision, Cryo-Innovation, 1 picture/10 min, intermittent whitelight illumination) under standard cultivation conditions (37.0 °C , 5% CO2 in humid air). Image sequences were digitally recorded for later use. For intravital spindle detection we used polaryzing microscopy (Oosight, Research Instruments) and Hoechst 33342 fluorescent dye for intravital chromatin visualization. A total number of 180 human embryos which gave a vital pregnancies (FHB, fetal heart beat) were analysed retrospectively for timing of early cleavages. In our study, the exact timing of the four interphases (IP) and synchrony of sister cell divisions (ID, interval division) occurring after fertilization were identified and manually recorded. Interphases: IP1 was defined as the period from fertilization till 2 cell stage. IP2 between 2 and 3 cells stages, IP3 between 3 and 5 and IP4 between 5 and 9 cells embryo. Interval division: ID2 was recorded as a time interval between 3 and 4 cells, ID3 between 5 and 8 cells and ID4 between 9 and 16 cells stage embryos. Results: In the embryos giving viable pregnancies, the durations of IP1 was 20–26 hrs. IP2 was 10–12 hrs, IP3 was 14-16 hrs and IP4 was 20–26 hrs. In these embryos, the sister blastomeres cleaved in a very synchronous manner. The duration of ID1 was recorded to varry from 120 to 210 min. ID2 from 20 to 60 min., ID3 from 120 to 240 min. and ID4 from 230 to 360 min. Conclusion: The viable embryos cleave in a very similar time pattern which can be defined and applied as referencial value. Non-invasive monitoring of the timing of early embryo cleavages can be used as an objectively measurable predictor of human embryo.

• MeSH
• buněčné dělení MeSH
• buněčný cyklus MeSH
• časové faktory MeSH
• embryo savčí cytologie   ultrastruktura   MeSH
• embryonální struktury MeSH
• embryonální vývoj MeSH
• fertilizace in vitro MeSH
• interfáze MeSH
• kultivace embrya MeSH
• lidé MeSH
• mitóza genetika   MeSH
• nakládání s embryem MeSH
• referenční hodnoty MeSH
• reprodukovatelnost výsledků MeSH
• retrospektivní studie MeSH
• selekce (genetika) MeSH
• výzkum embrya MeSH
• zobrazování trojrozměrné MeSH
• Check Tag
• lidé MeSH
• ženské pohlaví MeSH

The divergence of two differentiating extraembryonic cell types (trophectoderm and primitive endoderm) from the pluripotent epiblast population (the source of fetal progenitor cells) by the blastocyst stage of mouse development relies upon the activation and execution of lineage-specific gene expression programmes. While our understanding of the central transcription factor 'effectors' directing these cell-fate choices has accumulated rapidly, what is less clear is how the differential expression of such genes within the diverging lineages is initially generated. This review summarizes and consolidates current understanding. I introduce the traditional concept and importance of a cell's spatial location within the embryo, referencing recent mechanistic and molecular insights relating to cell fate. Additionally, I address the growing body of evidence that suggests that heterogeneities among blastomeres precede, and possibly inform, their spatial segregation in the embryo. I also discuss whether the origins of such early heterogeneity are stochastic and/or indicative of intrinsic properties of the embryo. Lastly, I argue that the robustness and regulative capacity of preimplantation embryonic development may reflect the existence of multiple converging, if not wholly redundant, mechanisms that act together to generate the necessary diversity of inter-cell-lineage gene expression patterns.

• MeSH
• blastomery fyziologie   MeSH
• buněčná diferenciace fyziologie   MeSH
• buněčný rodokmen fyziologie   MeSH
• embryo savčí metabolismus   fyziologie   MeSH
• embryonální vývoj fyziologie   MeSH
• myši MeSH
• pohyb buněk fyziologie   MeSH
• transkripční faktory metabolismus   MeSH
• vývojová regulace genové exprese fyziologie   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH

The first embryonic division represents a starting point for the development of a new individual. In many species, tight control over the first embryonic division ensures its accuracy. However, the first division in humans is often erroneous and can impair embryo development. To delineate the spatiotemporal organization of the first mitotic division typical for normal human embryo development, we systematically analyzed a unique timelapse dataset of 300 IVF embryos that developed into healthy newborns. The zygotic division pattern of these best-quality embryos was compared to their siblings that failed to implant or arrested during cleavage stage. We show that division at the right angle to the juxtaposed pronuclei is preferential and supports faithful zygotic division. Alternative configurations of the first mitosis are associated with reduced clustering of nucleoli and multinucleation at the 2-cell stage, which are more common in women of advanced age. Collectively, these data imply that orientation of the first division predisposes human embryos to genetic (in)stability and may contribute to aneuploidy and age-related infertility.

• MeSH
• aparát dělícího vřeténka * metabolismus   MeSH
• buněčné jádro * metabolismus   MeSH
• embryo savčí cytologie   MeSH
• embryonální vývoj * MeSH
• fertilizace in vitro MeSH
• lidé MeSH
• mitóza * MeSH
• stadium rýhování vajíčka cytologie   MeSH
• zygota * metabolismus   cytologie   MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

DNA methylation/demethylation pattern, determined by 5-methylcytosine (5-MeC) immunostaining, was evaluated in porcine "in vivo" produced embryos from zygote up to the blastocyst stage. In one-cell stage embryos, only the maternal pronucleus showed a positive labeling whilst the paternal pronucleus showed almost no labeling. The intensity of labeling is high until the late morula stage. Blastocysts containing less than 100 cells showed the same intensity of labeling in both the inner cell mass (ICM) nuclei and the trophectodermal (TE) cell nuclei. Interestingly, with further cell multiplication, cells of the ICM became more intensively labeled when compared to TE cells. This distinct methylation pattern is even more profound in blastocysts containing about 200-300 cells and is not caused by the difference in the cell volume of ICM and TE cells.

• MeSH
• blastocysta metabolismus   MeSH
• chromatin metabolismus   MeSH
• embryo savčí embryologie   metabolismus   MeSH
• financování organizované MeSH
• metylace DNA MeSH
• prasata MeSH
• zvířata MeSH
• zygota metabolismus   MeSH
• Check Tag
• ženské pohlaví MeSH
• zvířata MeSH

Proper timing of degradation of maternal protein reserves is important for early embryonic development. The major modification that triggers proteins to degradation is ubiquitination, mediated by ubiquitin-proteolytic system. We focus here on Skp 1-Cul 1-F-box complex (SCF-complex), E3 ubiquitin-ligase, a part of ubiquitin-proteolytic system, which transfer ubiquitin to the substrate protein. We describe in this chapter the methods for the characterization of the expression profile of mRNA and protein of invariant members of SCF-complex and for the definition of SCF-complex activity.

• MeSH
• aktivace transkripce MeSH
• embryonální vývoj * MeSH
• proteinligasy komplexu SCF metabolismus   MeSH
• proteolýza MeSH
• skot MeSH
• stanovení celkové genové exprese MeSH
• ubikvitinligasy metabolismus   MeSH
• vývojová regulace genové exprese MeSH
• zvířata MeSH
• Check Tag
• skot MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

• MeSH
• kuřecí embryo MeSH
• lymfatické cévy anatomie a histologie   MeSH
• srdce MeSH
• Check Tag
• kuřecí embryo MeSH

In the Caenorhabditis elegans nematode, the oocyte nucleolus disappears prior to fertilization. We have now investigated the re-formation of the nucleolus in the early embryo of this model organism by immunostaining for fibrillarin and DAO-5, a putative NOLC1/Nopp140 homolog involved in ribosome assembly. We find that labeled nucleoli first appear in somatic cells at around the 8-cell stage, at a time when transcription of the embryonic genome begins. Quantitative analysis of radial positioning showed the nucleolus to be localized at the nuclear periphery in a majority of early embryonic nuclei. At the ultrastructural level, the embryonic nucleolus appears to be composed of a relatively homogenous core surrounded by a crescent-shaped granular structure. Prior to embryonic genome activation, fibrillarin and DAO-5 staining is seen in numerous small nucleoplasmic foci. This staining pattern persists in the germline up to the ∼100-cell stage, until the P4 germ cell divides to give rise to the Z2/Z3 primordial germ cells and embryonic transcription is activated in this lineage. In the ncl-1 mutant, which is characterized by increased transcription of rDNA, DAO-5-labeled nucleoli are already present at the 2-cell stage. Our results suggest a link between the activation of transcription and the initial formation of nucleoli in the C. elegans embryo.

• MeSH
• buněčné jadérko genetika   metabolismus   ultrastruktura   MeSH
• Caenorhabditis elegans embryologie   genetika   ultrastruktura   MeSH
• embryo nesavčí embryologie   ultrastruktura   MeSH
• genetická transkripce fyziologie   MeSH
• genom u helmintů fyziologie   MeSH
• jaderné proteiny genetika   metabolismus   MeSH
• proteiny Caenorhabditis elegans genetika   metabolismus   MeSH
• vývojová regulace genové exprese fyziologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH