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At least 415 records · Page 23Linked to original sources

PubMed2002

Screen for stage-specific expression genes between tail bud stage and heartbeat beginning stage in embryogenesis of gynogenetic silver crucian carp.

A systemic study was initiated to identify stage-specific expression genes in fish embryogenesis by using suppression subtractive hybridization (SSH) technique. In this study, we presented a preliminary result on screen for stage-specific expression genes between tail bud stage (TBS) and heartbeat beginning stage (HBS) in gynogenetic silver crucian carp (Carassius auratus gibelio). Two SSH plasmid libraries specific for TBS embryos and HBS embryos were constructed, and stage-specific expression genes were screened between the two stages. 1963 TBS positive clones and 2466 HBS positive clones were sampled to PCR amplification, and 1373 TBS and 1809 HBS PCR positive clones were selected to carry out dot blots. 169 TBS dot blot positive clones and 272 HBS dot blot positive clones were sequenced. Searching GenBank by using these nucleotide sequences indicated that most of the TBS dot blot positive clones could not be found homologous sequences in the database, while known genes were mainly detected from HBS dot blot positive clones. Of the 79 known genes, 20 were enzymes or kinases involved in important metabolism of embryonic development. Moreover, specific expressions of partial genes were further confirmed by virtual northern blots. This study is the first step for making a large attempt to study temporal and spatial control of gene expression in the gynogenetic fish embryogenesis.

Animals↗

PubMed2004

Overexpression of the tissue inhibitor of metalloproteinase-3 during Xenopus embryogenesis affects head and axial tissue formation.

Tissue inhibitors of metalloproteinases (TIMPs) modulate extracellular matrix remodeling during embryonic development and disease. TIMP-3 expression was examined during Xenopus laevis embryogenesis: TIMP-3 transcripts detected in the maternal pool of RNA increased at the mid-blastula transition, decreased dramatically during gastrulation and increased again during neurulation and axis elongation. Interestingly, the decrease during gastrulation was not seen in LiCl treated (dorsalized) embryos. Whole mount in situ hybridization of TIMP-3 using DIG-labeled RNA probes demonstrated that the transcripts were present in all dorsal tissues during embryogenesis, but were prominent only in head structures starting at stage 35. Overexpression of TIMP-3 through transgenesis and RNA injections led to developmental abnormalities and death. Both overexpression strategies resulted in post-gastrulation perturbation including those to neural and head structures, as well as truncated axes. However, RNA injections resulted in more severe early defects such as failure of neural tube closure, and transgenesis caused truncated axes and head abnormalities. No transgenic embryo expressing TIMP-3 survived past stage 40.

Abnormalities, Multiple↗

PubMed1982

The use of acetyl-CoA carboxylase activity and changes in wall composition as measures of embryogenesis in tissue cultures of oil palm (Elaeis guineensis).

With some lines of oil-palm tissue cultures embryogenesis occurs spontaneously within the callus grown on a medium containing 2.5 mg of 3-naphthylacetic acid/litre. One of the initial biochemical events that occurs just before the embryoid can be seen is the accumulation of fat droplets within the cells. This accumulation of lipid is correlated with an increase in acetyl-CoA carboxylase activity. The carboxylase is thus probably a rate-limiting step in fatty acid synthesis in these cells and can be used as a quantitative marker of somatic embryogenesis within the tissue. During the development of the embryoid tissue there is an increase in cell division and the differentiation of vascular cells with secondary thickened walls. These stages of the differentiation may be monitored by measuring the ratio of pectin synthesis (polygalacturonic acid formation) to hemicellulose synthesis (xylan formation).

Acetyl-CoA Carboxylase↗

PubMed1997

Proto-oncogene of int-3, a mouse Notch homologue, is expressed in endothelial cells during early embryogenesis.

BACKGROUND: Notch and its homologues are key regulatory receptors of the cell fate decision in various developmental processes. The int-3 oncogene was originally identified as a frequent target in Mouse Mammary Tumour Virus (MMTV)-induced mammary tumours and has been regarded as a Notch homologue, based on its similarity to the intracellular domain of Notch. Studies with int-3 transgenic mice have suggested that the int-3 transgene affects the differentiation capacity of stem cells and leads to neoplastic proliferation in epithelial cells. However, the exact nature and the in vivo expression pattern of the int-3 proto-oncogene are unknown. The function of gene products in embryogenesis is also not clear. RESULTS: We isolated cDNA clones corresponding to the proto-oncogene of int-3 and analysed its overall structure. The predicted amino acid sequence of the int-3 proto-oncogene contains the conserved motif found in Notch family receptors. Therefore, we name Notch-4 for the int-3 proto-oncogene. However, Notch-4 has fewer EGF repeats and shows less similarity to Notch, compared with other mammalian Notch homologues. In embryogenesis, the expression of Notch-4 was detected in endothelial cells of blood vessels forming tissues such as the dorsal aorta, intersegmental vessels, yolk sac vessels, cephalic vessels, heart, vessels in branchial arches, and capillary plexuses. In these tissues, Notch-4 expression coincided with flk-1, the major regulatory gene of vasculogenesis and angiogenesis. We also found that Notch-4 expression was up-regulated in vitro during the differentiation of endothelial cells from embryonic stem cells (ES cells). CONCLUSION: The endothelial cell specific expression pattern of Notch-4, as well as its structural similarity of Notch, suggest that Notch-4 is an endothelial cell specific homologue of Notch and it may play a crucial role in vasculogenesis and angiogenesis.

Amino Acid Sequence↗

PubMed2000

Gene regulation during late embryogenesis: the RY motif of maturation-specific gene promoters is a direct target of the FUS3 gene product.

The Arabidopsis mutants fus3 and abi3 show pleiotropic effects during embryogenesis including reduced levels of transcripts encoding embryo-specific seed proteins. To investigate the interaction between the B3-domain-containing transcription factors FUS3 and ABI3 with the RY cis-motif, conserved in many seed-specific promoters, a promoter analysis as well as band-shift experiments were performed. The analysis of promoter mutants revealed the structural requirements for the function of the RY cis-element. It is shown that both the nucleotide sequence and the alternation of purin and pyrimidin nucleotides (RY character) are essential for the activity of the motif. Further, it was shown that FUS3 and ABI3 can act independently of each other in controlling promoter activity and that the RY cis-motif is a target for both transcription factors. For FUS3, which is so far the smallest known member of the B3-domain family, a physical interaction with the RY motif was established. The functional and biochemical data demonstrate that the regulators FUS3 and ABI3 are essential components of a regulatory network acting in concert through the RY-promoter element to control gene expression during late embryogenesis and seed development.

2S Albumins, Plant↗

PubMed2004

The FUS3 transcription factor functions through the epidermal regulator TTG1 during embryogenesis in Arabidopsis.

Loss-of-function mutations in the FUSCA3 (FUS3) gene of Arabidopsis result in alterations in cotyledon identity, inability to complete late seed maturation processes, and the premature activation of apical and root embryonic meristems, which indicates that this transcription factor is an essential regulator of embryogenesis. Although FUS3 shows a complex pattern of expression in the embryo, this gene is only required in the protoderm to carry out its functions. Moreover, the epidermal morphogenesis regulator TRANSPARENT TESTA GLABRA1 (TTG1) is negatively regulated by FUS3 in the embryo. When a loss-of-function ttg1 mutation is introduced into a fus3 mutant, a number of fus3-related phenotypes are rescued, indicating a functional TTG1 gene is required to manifest the fus3 mutant phenotype. It therefore appears that one of the functions of FUS3 is to restrict the domain of expression of TTG1 during embryogenesis. The FUS3-TTG1 interaction is both maternal and zygotic, suggesting a complex relationship is required between these gene products to allow correct seed development.

Anthocyanins↗

PubMed1999

Dynamic and tissue-specific expression of eIF4E during zebrafish embryogenesis.

The regulation of protein synthesis is critical to diverse cellular processes and plays a pivotal role in regulating gene expression during embryogenesis. The cap-binding protein eIF4E is a translational factor whose activity appears to be both ubiquitous and central to the regulation of protein synthesis in all cell-types. As a cell-cycle regulator, mesoderm inducer and proto-oncogene, the amount and activity of the translational factor eIF4E must be under strict control, but the range of its expression and its concentration as a function of position and time in the developing embryo are unknown. Consequently, we have initiated studies to elucidate the expression of the eIF4E gene and its role in the regulating embryonic development. We have cloned a zebrafish gene encoding eIF4E, zeIF4E, and measured its developmental expression. Unexpectedly, we found that the zeIF4E gene produces two alternatively spliced transcripts that potentially encode different forms of the initiation factor. Molecular analyses and in situ hybridization reveal a potential role for eIF4E in regulating protein synthesis during vertebrate oogenesis, gastrulation, and erythropoiesis. The dynamic and asymmetric expression of eIF4E during zebrafish embryogenesis reveals that this ostensibly general translation factor may act as a tissue-specific translational enhancer.

Alternative Splicing↗

PubMed1999

A novel egg-derived tyrosine phosphatase, EDTP, that participates in the embryogenesis of Sarcophaga peregrina (flesh fly).

We have previously reported that cathepsin L mRNA is present in unfertilized eggs of Sarcophaga peregrina (flesh fly) as a maternal mRNA, which suggests that cathepsin L is required for embryogenesis. Now we have identified an egg protein, with a molecular mass of 100 kDa, that is extremely susceptible to cathepsin L digestion and which disappears rapidly as the embryos develop. We purified this protein to homogeneity, cloned its cDNA, and found that it contained a consensus sequence for the active site of tyrosine phosphatase. In fact this protein showed tyrosine phosphatase activity, indicating that it is a novel tyrosine phosphatase. The expression and subsequent disappearance of this protein, which we have named egg-derived tyrosine phosphatase (EDTP), may be indispensable for embryogenesis of Sarcophaga.

Amino Acid Sequence↗

PubMed1999

Dual specificity of activin type II receptor ActRIIb in dorso-ventral patterning during zebrafish embryogenesis.

Members of the transforming growth factor-beta (TGF-beta) superfamily are thought to regulate specification of a variety of tissue types in early embryogenesis. These effects are mediated through a cell surface receptor complex, consisting of two classes of ser/thr kinase receptor, type I and type II. In the present study, cDNA encoding zebrafish activin type II receptors, ActRIIa and ActRIIb was cloned and characterized. Overexpression of ActRIIb in zebrafish embryos caused dorsalization of embryos, as observed in activin-overexpressing embryos. However, in blastula stage embryos, ActRIIb induced formation of both dorsal and ventro-lateral mesoderm. It has been suggested that these inducing signals from ActRIIb are mediated through each specific type I receptor, TARAM-A and BMPRIA, depending on activin and bone morphogenetic protein (BMP), respectively. In addition, it was shown that a kinase-deleted form of ActRIIb (dnActRIIb) suppressed both activin- and BMP-like signaling pathways. These results suggest that ActRIIb at least has dual roles in both activin and BMP signaling pathways during zebrafish embryogenesis.

Activin Receptors, Type II↗

PubMed1999

Expression of five novel T-box genes and brachyury during embryogenesis, and in developing and regenerating limbs and tails of newts.

Several T-box genes are considered to play important roles in developing limbs, tails and neural retinae. Five novel T-box genes in the Japanese newt were isolated and their expression was analyzed, together with another T-box gene of brachyury, during embryogenesis and in the developing and regenerating limbs and tail. Four are designated CpTbx2, CpTbx3, CpTbx6R and CpEomesodermin based on molecular phylogenetic analyses, and the other is named CpUbiqT from its ubiquitous expression. While all were expressed during embryogenesis, only four of them (CpTbx2, CpTbx3, CpUbiqT and brachyury) were detected in developing limbs and/or tails. Except for brachyury, they were continuously expressed in normal adult appendages and showed elevated expression levels in regenerating limbs, whereas only CpTbx2 showed significant up-regulation in regenerating tails. Compared with orthologous genes in other species, CpTbx2, CpTbx3 and CpEomesodermin showed several notable differences such as an abundance of maternal transcripts of CpEomesodermin, a unique insertion sequence within the T-box domain of CpTbx2, and a lack of visible expression of CpTbx2and CpTbx3 in the apical ectodermal region of developing limbs. In view of the uniqueness of the newt, these results are discussed with respect to the possibility of their involvement in regeneration.

Amino Acid Sequence↗

PubMed2002

Essential role of growth factor receptor-mediated signal transduction through the mitogen-activated protein kinase pathway in early embryogenesis of the echinoderm.

In this study it was shown that growth factor receptors (GFR) play a crucial role in early embryogenesis of the echinoderms Hemicentrotus pulcherrimus and Clypeaster japonicus by transmitting signals to the mitogen-activated protein kinase (MAPK) pathway. The phosphorylation ratio of extracellular signal-regulated kinase 1 (ERK1) changed dynamically during early embryogenesis and showed a peak at the swimming blastula (sBl) stage. Suramin, an inhibitor of GFR, when applied during the sBl stage perturbed morphogenesis, including primary mesenchyme cell (PMC) migration, cell proliferation, archenteron elongation, spiculogenesis, pigment cell differentiation and phosphorylation of myosin light chains (MLC). Genistein, a receptor-type protein tyrosine kinase inhibitor, severely inhibited PMC migration, gastrulation and the phosphorylation of MLC. Manumycin A, a Ras inhibitor, inhibited spiculogenesis and invagination. PD98059, a MAPK/ERK kinase inhibitor, perturbed early PMC migration and pigment cell differentiation, but not spiculogenesis and gastrulation (although these two events were significantly delayed). PMC ingression was not perturbed by genistein, suramin, manumycin A or PD98059. All of the inhibitors perturbed the phosphorylation of ERK1, which was completely restored by exogenous platelet-derived growth factor (PDGF)-AB. PDGF-AB also partially restored elongation of the archenteron by restoring cell proliferation that had been perturbed by suramin.

Animals↗

PubMed2005

Telomere length regulation during cloning, embryogenesis and ageing.

Telomeres are nucleoprotein complexes at the end of eukaryotic chromosomes with an essential role in chromosome capping. Owing to the end-replication problem of DNA polymerase, telomeres shorten during each cell division. When telomeres become critically short, they loose their capping function, which in turn induces a DNA damage-like response. This mechanism inhibits cell proliferation at the senescence stage and there is evidence that it limits the regenerative capacity of tissues and organs during chronic diseases and ageing. The holoenzyme telomerase synthesises telomeric DNA de novo, but, in humans, it is active only during embryogenesis, in immature germ cells and in a subset of stem/progenitor cells during postnatal life. Telomere length can be maintained or increased by telomerase, a process that appears to be regulated by a variety of telomere-binding proteins that control telomerase recruitment and activity at the telomeres. During embryogenesis, telomerase is strongly activated at the morula/blastocyst transition. At this transition, telomeres are significantly elongated in murine and bovine embryos. Early embryonic telomere elongation is telomerase dependent and leads to a rejuvenation of telomeres in cloned bovine embryos. Understanding of the molecular mechanisms underlying this early embryonic telomere elongation programme is of great interest for medical research in the fields of regeneration, cell therapies and therapeutic cloning.

Aging↗

PubMed2004

AtNAP7 is a plastidic SufC-like ATP-binding cassette/ATPase essential for Arabidopsis embryogenesis.

In bacteria, yeast, and mammals, iron-sulfur (Fe-S) cluster-containing proteins are involved in numerous processes including electron transfer, metabolic reactions, sensing, signaling, and regulation of gene expression. In humans, iron-storage diseases such as X-linked sideroblastic anemia and ataxia are caused by defects in Fe-S cluster availability. The biogenesis of Fe-S clusters involves several pathways, and in bacteria, the SufABCDSE operon has been shown to play a vital role in Fe-S biogenesis and repair during oxidative stress. Although Fe-S proteins play vital roles in plants, Fe-S cluster biogenesis and maintenance and physiological consequences of dysfunctional Fe-S cluster assembly remains obscure. Here we report that Arabidopsis plants deficient for the SufC homolog AtNAP7 show lethality at the globular stage of embryogenesis. AtNAP7 is expressed in developing embryos and in apical, root, and floral meristems and encodes an ATP-binding cassette/ATPase that can partially rescue growth defects in an Escherichia coli SufC mutant during oxidative stress. AtNAP7 is plastid-localized, and mutant embryos contain abnormal developing plastids with disorganized thylakoid structures. We found that AtNAP7 can interact with AtNAP6, a plastidic Arabidopsis SufD homolog, and because Arabidopsis plastids also harbor SufA, SufB, SufS, and SufE homologs, plastids probably contain a complete SUF system. Our results imply that AtNAP7 represents a conserved SufC protein involved in the biogenesis and/or repair of oxidatively damaged Fe-S clusters and suggest an important role for plastidic Fe-S cluster maintenance and repair during Arabidopsis embryogenesis.

ATP-Binding Cassette Transporters↗

PubMed2005

Subdomains for transport via plasmodesmata corresponding to the apical-basal axis are established during Arabidopsis embryogenesis.

The axial body pattern of Arabidopsis is determined during embryogenesis by auxin signaling and differential gene expression. Here we demonstrate that another pathway, cell-to-cell communication through plasmodesmata (PD), is regulated during apical-basal pattern formation. The SHOOT MERISTEMLESS (STM) promoter was used to drive expression in the shoot apical meristem (SAM) and a subset of cells at the base of the hypocotyl of 1x,2x, and 3x soluble green fluorescent proteins (sGFPs), and the P30 movement protein of Tobacco mosaic virus (TMV) translationally fused to 1x and 2x sGFP. In the early heart stage, 2x sGFP (54 kDa) moves throughout the whole embryo, whereas 3x sGFP (81 kDa) shows more restricted movement. As the embryo develops, PD apertures are down regulated to form local subdomains allowing transport of different sized tracers. For example, movement of 2x sGFP to the cotyledon, and 3x sGFP to root tips, becomes restricted. Subdomains of cell-to-cell transport align with the apical-basal embryo body axis and correspond to the shoot apex, cotyledons, hypocotyl, and root. Studies with P30-GFP fusions reinforce the distinction between embryonic symplastic subdomains. Although P30 targets embryo cell walls as puncta (diagnostic for functional localization of P30 to PD in adult plants), P30 cannot dilate embryonic PD to overcome the barriers for transport between symplastic subdomains, suggesting that specific boundaries separate symplastic subdomains of the embryo. Thus, cell-to-cell communication via plasmodesmata conveys positional information critical to establish the axial body pattern during embryogenesis in Arabidopsis.

Arabidopsis↗

PubMed2005

Cysteine protease mcII-Pa executes programmed cell death during plant embryogenesis.

Programmed cell death (PCD) is indispensable for eukaryotic development. In animals, PCD is executed by the caspase family of cysteine proteases. Plants do not have close homologues of caspases but possess a phylogenetically distant family of cysteine proteases named metacaspases. The cellular function of metacaspases in PCD is unknown. Here we show that during plant embryogenesis, metacaspase mcII-Pa translocates from the cytoplasm to nuclei in terminally differentiated cells that are destined for elimination, where it colocalizes with the nuclear pore complex and chromatin, causing nuclear envelope disassembly and DNA fragmentation. The cell-death function of mcII-Pa relies on its cysteine-dependent arginine-specific proteolytic activity. Accordingly, mutation of catalytic cysteine abrogates the proteolytic activity of mcII-Pa and blocks nuclear degradation. These results establish metacaspase as an executioner of PCD during embryo patterning and provide a functional link between PCD and embryogenesis in plants. Although mcII-Pa and metazoan caspases have different substrate specificity, they serve a common function during development, demonstrating the evolutionary parallelism of PCD pathways in plants and animals.

Apoptosis↗

PubMed2006

Genes directly regulated by LEAFY COTYLEDON2 provide insight into the control of embryo maturation and somatic embryogenesis.

The B3 domain protein LEAFY COTYLEDON2 (LEC2) is required for several aspects of embryogenesis, including the maturation phase, and is sufficient to induce somatic embryo development in vegetative cells. Here, we demonstrate that LEC2 directly controls a transcriptional program involved in the maturation phase of seed development. Induction of LEC2 activity in seedlings causes rapid accumulation of RNAs normally present primarily during the maturation phase. Several RNAs encode proteins with known roles in maturation processes, including seed-storage and lipid-body proteins. Clustering analyses identified other LEC2-induced RNAs not previously shown to be involved in the maturation phase. We show further that genes encoding these maturation RNAs all possess in their 5' flanking regions RY motifs, DNA elements bound by other closely related B3 domain transcription factors. Our finding that recombinant LEC2 specifically binds RY motifs from the 5' flanking regions of LEC2-induced genes provides strong evidence that these genes represent transcriptional targets of LEC2. Although these LEC2-induced RNAs accumulate primarily during the maturation phase, we show that a subset, including AGL15 and IAA30, accumulate in seeds containing zygotes. We discuss how identification of LEC2 target genes provides a potential link between the roles of LEC2 in the maturation phase and in the induction of somatic embryogenesis.

Arabidopsis↗

PubMed2003

AthPEX10, a nuclear gene essential for peroxisome and storage organelle formation during Arabidopsis embryogenesis.

In yeasts and mammals, PEX10 encodes an integral membrane protein with a C3HC4 RING finger motif in its C-terminal domain and is required for peroxisome biogenesis and matrix protein import. In humans, its dysfunction in peroxisome biogenesis leads to severe Zellweger Syndrome and infantile Refsum disease. Here we show that dysfunction of a homologous gene in Arabidopsis leads to lethality at the heart stage of embryogenesis, impairing the biogenesis of peroxisomes, lipid bodies, and protein bodies. In a T-DNA insertion mutant disrupting the fourth exon of the AthPEX10 gene, ultrastructural analyses fail to detect peroxisomes characteristic for wild-type embryogenesis. Storage triacyl glycerides are not assembled into lipid bodies (oil bodies; oleosomes) surrounded by the phospholipid-protein monolayer membrane. Instead, the dysfunctional monolayer membranes, which derive from the bilayer membrane of the endoplasmic reticulum, accumulate in the cytosol. Concomitantly the transfer of the storage proteins from their site of synthesis at the endoplasmic reticulum to the vacuoles is disturbed. The mutant can be rescued by transformation with wild-type AthPEX10 cDNA. Transformants of wild-type Hansenula polymorpha cells with the AthPEX10 cDNA did produce the encoded protein without targeting it to peroxisomes. Additionally, the cDNA could not complement a Hansenula pex10 mutant unable to form peroxisomes. The ultrastructural knockout phenotype of AthPEX10p suggests that this protein in Arabidopsis is essential for peroxisome, oleosome, and protein transport vesicle formation.

Amino Acid Sequence↗

PubMed1978

Evidence for translocation of DNA sequences during sea urchin embryogenesis.

Hairpin-like DNA was prepared in vitro from the family of sequences that are inverted relative to each other and, as pairs, are relatively homologous and adjacent on the sea urchin genome. The majority of these hairpins are shown to have base pair mismatch positions distributed along their stems. Comparison of the hairpins derived from the DNA of morula, blastula, and gastrula stage embryos shows that during embryogenesis there are changes in the average number and position of S1 nuclease-sensitive base pair mismatch sites on the majority of the hairpin stems. Our data indicate that during early embryogenesis there are sequence changes in vivo within the majority of the adjacent inverted repeat sequences of the sea urchin genome. We have also found that there is higher specificity for the occurrence of sequence-change events within that fraction of the inverted repeat sequences that are methylated in vivo.

Animals↗