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At least 883 records · Page 49Linked to original sources

PubMed2000

Molecular characterization of a Litomosoides sigmodontis protein involved in the development of the microfilarial sheath during embryogenesis.

A cDNA clone Ls110 was isolated from a female Litomosoides sigmodontis expression library using an antiserum raised against the microfilarial sheath. The complete cDNA encodes a protein (Ls110) of 382 amino acids. Southern and PCR analyses revealed the presence of Ls110 in L. sigmodontis as a single copy gene. The transcription of the Ls110 gene was limited to female worms. In these worms the transcription was confined to the epithelial cells of the uterus. The protein Ls110 was detected not only in the epithelial layer of the uterus but also secreted in the lumen of the uterus. All the intra-uterine embryonic stages showed the protein bound to their egg shell/sheath, except the early multicellular embryonic stages and fully developed microfilariae. The transient occurrence of Ls110 on these structures of intra-uterine stages besides the presence of a cysteine-rich N-terminal region (SXC-like domain) suggest that the protein may play a role in the formation of the microfilarial sheath during embryogenesis.

Amino Acid Sequence↗

PubMed2000

Regulation of rat heat shock factor 2 expression during the early organogenic phase of embryogenesis.

A central step in the transcriptional regulation of heat shock protein (hsp) genes is the binding of the heat shock factor (HSF) to the upstream heat shock elements (HSEs). In vertebrates, HSF2 has been suggested to mediate the transcriptional regulation of hsp gene expression during development and differentiation. The expression levels of HSF2 were shown to vary widely among fully developed mouse organs. However, there exists limited information on the regulation of HSF2 expression during the inductive stage of organ formation in mammalian development. In this study, we have cloned the rat HSF2 cDNA and examined embryos for HSF2 expression from days 9.5 (E9.5) to 15.5 (E15.5) of gestation that correspond to the period when the major organ primordia are being actively established. We show that rat HSF2 has 94.6 and 96.3% identity to mouse HSF2 in nucleotide and amino acid sequences, respectively. By establishing a competitive RT-PCR, we show that about 503.6 pg of HSF2 mRNA were present per microgram of embryonic RNA in the primitive streak stage E9.5 embryos. The amounts of HSF2 mRNA then gradually decreased, resulting in an approximately 300-fold reduction in E15.5 embryos. The amounts of HSF2 mRNA in the embryos were found to be closely correlated with those of HSF2 protein and their HSE-binding activities. To our knowledge, this is the first detailed report on the structure and regulation of the rat HSF2 during the early organogenic period of mammalian embryogenesis.

Amino Acid Sequence↗

PubMed1997

Members of the AAA-gene family are involved in early embryogenesis of vertebrates.

Here the nucleotide sequence of three cDNAs from Xenopus laevis are reported. The corresponding genes belong to the AAA-family of genes showing the strongest sequence homology to the human HIV-1 Tat binding protein 1 (TBP-1) and to the yeast SUG1 gene, respectively. Analysis of their expression pattern indicate that they are maternally stored in oocytes and involved in very early stages of vertebrate embryogenesis.

Adenosine Triphosphatases↗

PubMed1999

Expression of novel homeobox genes in early embryogenesis in rice.

We isolated four novel cDNA clones of rice (Oryza sativa L.), which encode predicted proteins with a KN1-like homeodomain. In situ hybridization and RT-PCR analysis with solid cDNA libraries as templates showed that these genes are expressed in distinct patterns during the early stages of rice embryogenesis.

Amino Acid Sequence↗

PubMed2000

Histological analysis of indirect somatic embryogenesis in the Marsh clubmoss Lycopodiella inundata (L.) Holub (Pteridophytes).

An efficient in vitro plant regeneration method was developed for Lycopodiella inundata (L.) Holub, an endangered medicinal Lycopod (Pteridophytes). Vegetative apices were used as explant material. Nodular calluses were established after three cycles (13 weeks each) on a medium containing a few minerals and organic compounds and supplemented with 0.05 µM 3-indolebutyric acid (IBA) and 1.4 µM kinetin (Kin). Propagation was achieved every 13 weeks on this callus medium (CM). When nodular calluses were transferred on a medium supplemented with 2.5 µM IBA and 0.33 µM gibberellic acid (GA(3)) designated as embryogenic medium (EM), organized structures appeared and developed into plantlets. Development phases were characterized by histological studies. Some phases of zygotic embryogenesis previously described for Lycopods were observed in L. inundata. Histological analyses established that an indirect somatic embryo was derived from a single embryogenic cell by following the zygotic developmental pathway. As this phenomenon has not previously been reported in Lycopods, a comparison between somatic and zygotic embryos is discussed based upon morphology and histology.

Journal Article↗

PubMed2000

Cytokinin-induced somatic embryogenesis and plant regeneration in Corydalis yanhusuo (Fumariaceae) - a medicinal plant.

An efficient method has been developed for regeneration of complete plants via somatic embryogenesis in Corydalis yanhusuo (Fumariaceae), an important medicinal plant, using tuber-derived callus. Primary callus was induced by culturing mature tuber pieces on Murashige and Skoog's (MS) medium supplemented with 2.0 mg l(-1) N(6)-benzyladenine (BA) and 0.5 mg l(-1) alpha-naphthaleneacetic acid (NAA) in darkness. Somatic embryos were induced by subculturing the primary callus on MS medium supplemented with 0.5-4.0 mg l(-1) BA, kinetin, or zeatin, within 2 weeks of culture in light. Embryos with well-developed cotyledonary leaves were transferred in half-strength liquid MS medium supplemented with 1.0 mg l(-1) zeatin riboside for the development of roots. Converted somatic embryos were cultured on half-strength MS medium supplemented with 6% sucrose, and with 0.5-10.0 mg l(-1) abscisic acid (ABA), paclobutrazol, or ancymidol, 0.5-5.0 mg l(-1) GA(3) and 15-100 mg l(-1) polyethylene glycol (PEG) 4000 for further development of plantlets and in vitro tuber formation. The development of somatic embryos over the surface of tuber and/or cotyledonary leaf base region of the converted primary somatic embryo was observed. Before ex vitro establishment of somatic embryo-derived plants, plants with well-developed tubers were cultured on half-strength MS medium with 2% sucrose and 0.1 mg l(-1) GA(3) for 3 weeks.

Journal Article↗

PubMed2001

Ontogenic variations in n-alkanes during somatic embryogenesis of flax (Linum usitatissimum L.).

Hypocotyl segments (HS) of flax seedlings germinated in vitro, were used to induce indirect somatic embryogenesis on solid medium. The composition and distribution of n-alkanes in flax tissues collected at different developmental stages were studied by capillary gas chromatography (GC) and capillary gas chromatography-mass spectrometry (GC-MS). During induction and development of callus from hypocotyl tissues a decrease in the percentage of total lipids was observed. In all types of tissue sampled - HS used as primary explants, HS with differentiating calli at the cut ends (HSC), embryogenic (EC) and non-embryogenic calli (NEC) and somatic embryos (SE) - a skewed-normal distribution of n-alkanes with a low mass range (C(13)-C(21)) were found. The highest content of n-alkanes occurred in the primary hypocotyl explants and in the early stages of callus development. Longer carbon chain n-alkanes were observed only in the mature or differentiated tissues of hypocotyls and SE. Although the n-alkane contents decreased with time, in SE and calli, a significantly lower n-alkane content was observed in EC when compared to NEC independent of the time in culture. These results suggest the utilisation of n-alkanes for heterotrophic cellular growth as well as its mobilisation from EC to developing SE.

Journal Article↗

PubMed2000

Plant regeneration from callus and suspension cultures of Valeriana edulis ssp. procera via simultaneous organogenesis and somatic embryogenesis.

Plants of the genus Valeriana produce irioid esters of biotechnological interest, known as valepotriates. The regeneration of Valeriana edulis ssp. procera via indirect organogenesis and somatic embryogenesis from leaf-derived callus and suspension cultures, is presented. For induction of callus, leaves were cultured on semisolid MS medium supplemented with 2,4-dichlorophenoxyacetic acid (2,4-D) and kinetin. Embryogenic and organogenic callus development was observed after 16 weeks. Calli were transferred to semisolid and liquid Murashige and Skoog (MS) medium supplemented with kinetin and 1-naphthaleneacetic acid (NAA). Appearance of shoot and somatic embryo occurred 4 weeks later. Shoots were rooted and somatic embryos were germinated and were transferred to the greenhouse. A better organogenic and embryogenic response was observed from suspension cultures. Histological observations of morphogenic callus revealed that both somatic embryos and shoots arose from the same type of callus.

Journal Article↗

PubMed1995

A graphic digital database of Drosophila embryogenesis.

Modern studies of the genetic control of development have increased the need for an accurate and comprehensive storage and display of gene expression data. This can be achieved in the form of an electronic graphic database of development. Here, we introduce the first steps towards a database of Drosophila embryogenesis. For each morphologically defined stage, a complete series of histological and/or optical sections are generated (optical sections are generated by laser confocal microscopy). Digitized sections are imported into a drawing program where they serve as templates to define the contours of organs and the position of individual cells. From these data, surface and point cloud models of all developmental stages are generated. Gene expression data can be entered by translating the expression domain of a given gene into the three-dimensional coordinate system of the database.

Analog-Digital Conversion↗

PubMed2000

Integrins: regulators of embryogenesis.

Integrins are heterodimeric transmembrane glycoproteins involved in cell-cell and cell-extracellular matrix adhesion. They also participate in cytoskeletal rearrangements, co-regulation of growth factor activities and activation of signal transductions. This review describes experimental approaches that have given new insights into the integrin functions during embryogenesis. Using anti-functional antibodies, peptide inhibitors of integrin-ligand interactions and genetic ablation of integrins results, this review will show that integrins are key molecules during early development of both invertebrates and vertebrates.

Animals↗

PubMed2001

Expression of the Daucus carota somatic embryogenesis receptor kinase (DcSERK) protein in insect cells.

The Daucus carota somatic embryogenesis receptor kinase (DcSERK) gene serves as marker to monitor the transition from somatic into embryogenic plant cells. To determine the intrinsic biochemical properties of the DcSERK protein, a predicted transmembrane receptor, the kinase domain was expressed as a 40-kDa his-tag fusion protein in the baculovirus insect cell system. The kinase domain fusion protein was able to autophosphorylate in vitro. Phosphoamino acid analysis of the autophosphorylated DcSERK protein revealed that it was autophosphorylated on serine and threonine residues. This is the first evidence of the biochemical characterization of a transmembrane receptor kinase from embryogenic plant cell cultures.

Amino Acid Sequence↗

PubMed1999

Comparison of munc-18 and cdk5 expression in the nervous system during mouse embryogenesis.

Cyclin-dependent kinase-5 (Cdk5) and its neuron-specific activator, p35, are essential for the proper migration of neurons. While the defects in p35 null mice are largely confined to the cerebral cortex, the anomalies in cdk5 nullizygous mice are also evident in the hippocampus and cerebellum. This suggested that additional cyclin-like activators, such as Munc-18, must be coexpressed with Cdk5 in some migrating neurons. Therefore, the expression patterns of munc-18 and cdk5 were determined in the developing mouse nervous system by in situ hybridization. In the embryonic day 11.5-13.5 developing neocortex, cdk5 was expressed in the proliferative zone and also in migratory and postmitotic neurons. In contrast, munc-18 messenger RNA was only detected in postmigratory, differentiated neurons. In the cerebellum and the hippocampus, cdk5 was expressed in proliferative, migrating and postmigratory neurons, while munc-18 was expressed in migrating and postmigratory neurons. This supports the hypothesis that Munc-18 could compensate for the loss of p35 in migrating neurons in the hippocampus and cerebellum, but not the cerebral cortex. Munc-18 levels increased substantially during late embryogenesis and into adulthood. Therefore, the function of Munc-18 is most likely relevant to mature neurons and any redundancy with p35 in migration is probably fortuitous.

Animals↗

PubMed2003

Vacuolar-type H+-ATPase E subunit is required for embryogenesis and yolk transfer in Caenorhabditis elegans.

Vacuolar H(+)-ATPases (V-ATPases) are ATP-dependent proton pumps localized at membranes of intracellular acidic organelles and plasma membranes of various cell types. By virtue of its regulation in acidification, V-ATPase is required for many intracellular processes such as receptor-mediated endocytosis and protein sorting. Here we report the molecular characterization of the E subunit of V-ATPase in Caenorhabditis elegans. This subunit is one of the most well conserved subunits sharing approximately 57% identity with the human homologue, ATP6E. Green fluorescent protein (GFP) and whole-mount immunostaining analyses showed that V-ATPase E subunit (vha-8) is abundantly expressed in the H-shaped excretory cell, consistent with the expression patterns observed for other V-ATPase subunits. Double-stranded RNAs (or RNAi) targeted to vha-8 resulted in embryonic and larval lethality for the first filial generation, indicating that vha-8 is essential during early developmental processes. In addition, accumulation of abnormal endomitotic oocytes and defects in receptor-mediated endocytosis were observed in parental animals. These findings suggest that multiple phenotypes caused by the disruption of pH homeostasis are due to the defective V-ATPase. In summary, vha-8 encoding the E subunit of V-ATPase in C. elegans is essential for embryogenesis and receptor-mediated endocytosis.

Amino Acid Sequence↗

PubMed1997

Cloning of Drosophila MCM homologs and analysis of their requirement during embryogenesis.

MCM (minichromosome maintenance) gene family of Saccharomyces cerevisiae encodes essential DNA replication factors that participate in the initiation of DNA replication. In addition, their localization to the nucleus in a mitosis-dependent manner fueled the hypothesis that MCMs also act to couple DNA replication to mitosis. We report the identification of a Drosophila gene family with extensive sequence identity to the MCM genes. Results from antibody injection experiments suggest that MCMs play an essential role in DNA replication during embryogenesis. Evolutionary conservation of MCM sequences and function in Drosophila could potentially facilitate studies of how initiation of DNA replication is regulated and coupled to mitosis during metazoan development.

Amino Acid Sequence↗

PubMed1998

Structure of the mouse osteoclastogenesis inhibitory factor (OCIF) gene and its expression in embryogenesis.

Osteoclastogenesis inhibitory factor (OCIF) is a novel soluble-form member of the tumor necrosis factor receptor family and is involved in the regulation of bone mass. Here we isolated genomic and cDNA clones for mouse OCIF and determined their structures. Mouse OCIF gene spans 29 kb and contains five exons of 270, 367, 192, 225 and 1765 bp long. Four cysteine-rich domains and two death domain homologous regions characterized in human OCIF are rigidly conserved in mouse OCIF. The onset of OCIF gene expression in mouse embryogenesis is at day 8.5. In a pregnant female mouse, OCIF gene is expressed in decidua, a maternal tissue surrounding each embryo, immediately after implantation. The isolation of mouse OCIF gene should facilitate studies on OCIF knock-out mice for a better understanding of the role of OCIF in vivo.

Amino Acid Sequence↗

PubMed1999

A Drosophila derailed homolog, doughnut, expressed in invaginating cells during embryogenesis.

Members of the RYK family of receptors are homologous to tyrosine kinases but do not exhibit kinase activity in vitro. We describe a new member of this family in Drosophila, which we call Doughnut (DNT). The protein product was found to be 70% identical to the Drosophila Derailed (DRL) protein and 35-40% identical to the mammalian RYK proteins. During Drosophila embryogenesis, DNT was found to be expressed in a highly dynamic pattern, including many invaginating cells. Many aspects of the expression pattern resembled that of unpaired, a gene that encodes a secreted protein that stimulates the Drosophila JAK/STAT signaling pathway. RYK proteins contain amino acid substitutions at residues that are highly conserved amongst proteins that exhibit kinase activity. Therefore, it has been unclear whether RYK family members are catalytically active or, if they are not, how they might transduce a signal. When expressed in cell culture DNT became phosphorylated on tyrosine, as did a mutant form of the receptor, containing an arginine residue in place of lysine within the predicted nucleotide binding site. These results suggest that DNT associates with a catalytically active kinase, but may not be capable of autophosphorylation.

Amino Acid Sequence↗

PubMed2000

An ascidian glycine-rich RNA binding protein is not induced by temperature stress but is expressed under a genetic program during embryogenesis.

We have cloned a putative ascidian glycine-rich RNA binding protein gene, CiGRP1. Its maternal transcript and protein are stored in the unfertilized egg. They are gradually decreased during the first few rounds of cleavage. The CiGRP1 zygotic transcript and protein start to accumulate at the gastrula stage. The CiGRP1 transcript is expressed in the brain precursor and mesenchyme precursor cells of the gastrula and the neurula stage, and the brain and mesenchyme cells of the tailbud stage embryo. The CiGRP1 protein is found in all nuclei and in the cytoplasm of brain and mesenchyme cells. Although many glycine-rich RNA binding protein homologs of plants and vertebrates are cold-inducible, CiGRP1 cannot be induced by cold shock or heat shock at the transcriptional and translational levels during embryogenesis. The temporal expression pattern and the tissue-restricted expression pattern of CiGRP1 suggest that it has important roles in the very early stage of development and in the brain and the mesenchyme tissue specification.

Amino Acid Sequence↗

PubMed2000

Synthesis of 60- and 72 kDa heat shock proteins in early porcine embryogenesis.

Proteins of selected embryonic stages were metabolically labeled with [(35)S]-methionine and analyzed by two-dimensional SDS-polyacrylamide gel electrophoresis (2-D PAGE) to study protein expression from 4- to 8-cell to blastocyst stage of porcine embryos. Two proteins with molecular weights of 60 and 72kDa were de novo synthesized during the 4- to 8-cell stage were the earliest that were detected. They were identified as HSP60 and HSP72 according to their locations on 2-D autoradiography and the immunoblotting result of anti-HSP 60 and HSP 72 antibodies of 1-cell stage of porcine embryos. In protein translation in early pig embryogenesis the timing of their synthesis suggests that HSP60 and HSP72 play significant roles as chaperones.

Animals↗