Abstract:
:Ultrastructural features of embryogenic pollen in Datura innoxia are described, just prior to, during, and after completion of the first division of the presumptive vegetative cell. In anther cultures initiated towards the end of the microspore phase and incubated at 28 degrees C in darkness, the spores divide within 24 h and show features consistent with those of dividing spores in vivo. Cytokinesis is also normal in most of the spores and the gametophytic cell-plate curves round the presumptive generative nucleus in the usual highly ordered way. Further differentiation of the 2 gametophytic cells does not take place and the pollen either switches to embryogenesis or degenerates. After 48-72 h, the remaining viable pollen shows the vegetative cell in division. The cell, which has a large vacuole and thin layer of parietal cytoplasm carried over from the microspore, divides consistently in a plane parallel to the microspore division. The dividing wall follows a less-ordered course than the gametophytic wall and usually traverses the vacuole, small portions of which are incorporated into the daughter cell adjacent to the generative cell. The only structural changes in the vegetative cell associated with the change in programme appear to be an increase in electron density of both plastids and mitochondria and deposition of an electron-dense material (possibly lipid) on the tonoplast. The generative cell is attached to the intine when the vegetative cell divides. Ribosomal density increases in the generative cell and exceeds that in the vegetative cell. A thin electron-dense layer also appears in the generative-cell wall. It is concluded that embryogenesis commences as soon as the 2 gametophytic cells are laid down. Gene activity associated with postmitotic synthesis of RNA and protein in the vegetative cell is switched off. The data are discussed in relation to the first division of the embryogenic vegetative cells in Nicotiana tabacum.
journal_name
J Cell Scijournal_title
Journal of cell scienceauthors
Dunwell JM,Sunderland Nsubject
Has Abstractpub_date
1976-12-01 00:00:00pages
469-80issue
3eissn
0021-9533issn
1477-9137journal_volume
22pub_type
杂志文章abstract::Structures resembling nuclei but depleted of protein may be released by gently lysing cells in solutions containing non-ionic detergents and high concentrations of salt. These nucleoids sediment in gradients containing intercalating agents in a manner characteristic of DNA that is intact, supercoiled and circular. The...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1976-11-01 00:00:00
abstract::The characterization of the Caenorhabditis elegans unc-47 gene recently allowed the identification of a mammalian (gamma)-amino butyric acid (GABA) transporter, presumed to be located in the synaptic vesicle membrane. In situ hybridization data in rat brain suggested that it might also take up glycine and thus represe...
journal_title:Journal of cell science
pub_type: 杂志文章
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更新日期:1999-03-01 00:00:00
abstract::Peroxinectin, a cell-adhesive peroxidase (homologous to human myeloperoxidase), from the crayfish Pacifastacus leniusculus, was shown by immuno-fluorescence to bind to the surface of crayfish blood cells (haemocytes). In order to identify a cell surface receptor for peroxinectin, labelled peroxinectin was incubated wi...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1999-03-01 00:00:00
abstract::BN46/51 is an acidic protein found in the granular component of the nucleolus of the amebo-flagellate Naegleria gruberi. When Naegleria amebae differentiate into swimming flagellates, BN46/51 is found associated with the basal body complex at the base of the flagella. In order to determine the factors responsible for ...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1999-04-01 00:00:00
abstract::Behaviour of epitheliocytes and fibroblasts on special discontinuous substrata (metallic grids with square openings of 45x45 microm2) was examined in order to compare the ability of these cells to spread in two mutually perpendicular directions and to stretch over the void spaces. Two cell types with typical fibroblas...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1999-04-01 00:00:00
abstract::An apparatus is described by means of which the power versus frequency spectrum of the photomultiplier current can be obtained for laser light scattered by streaming cytoplasm in the algal cell Chara corallina. A Doppler peak is noted in the spectrum which is abolished when cytoplasmic streaming is arrested by electri...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1976-12-01 00:00:00
abstract::We have generated 9 site-specific mutations in Saccharomyces cerevisiae actin. These mutants display a variety of phenotypes when expressed in vivo, including slow actin filament turnover, slow fluid-phase endocytosis, and defects in actin organization. Actin mutation D157E confers resistance to the actin-sequestering...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1999-05-01 00:00:00
abstract::Myogenesis proceeds by fusion of proliferating myoblasts into myotubes under the control of various transcription factors. In adult skeletal muscle, myogenic stem cells are represented by the satellite cells which can be cultured and differentiate in vitro. This system was used to investigate the subcellular distribut...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1999-04-01 00:00:00
abstract::Fibrillin-1, the main component of 10-12 nm microfibrils of the extracellular matrix, is synthesized as profibrillin and proteolytically processed to fibrillin. The putative cleavage site has been mapped to the carboxy-terminal domain of profibrillin-1, between amino acids arginine 2731 and serine 2732, by a spontaneo...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1999-04-01 00:00:00
abstract::A two-hybrid screening in yeast for proteins interacting with the human hnRNP A1, yielded a nuclear protein of 917 amino acids that we termed hnRNP A1 associated protein (HAP). HAP contains an RNA binding domain (RBD) flanked by a negatively charged domain and by an S/K-R/E-rich region. In in vitro pull-down assays, H...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1999-05-01 00:00:00
abstract::Zellweger syndrome and related disorders represent a group of lethal, genetically heterogeneous diseases. These peroxisome biogenesis disorders (PBDs) are characterized by defective peroxisomal matrix protein import and comprise at least 10 complementation groups. The genes defective in seven of these groups and more ...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1999-05-01 00:00:00
abstract::Dendritic cells are professional antigen presenting cells that capture antigens and migrate to lymphoid tissues to elicit specific T cell responses. Here we used an in vitro differentiation system for generating highly motile dendritic cells from chicken bone marrow progenitors by employing the conditional v-Rel estro...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1999-06-01 00:00:00
abstract::Sugar moieties have been shown to contain sufficient and necessary information to target examples of secreted and transmembrane glycoproteins to the apical surface of epithelial MDCK cells. We have investigated if the sugar chains of proteoglycans, the glycosaminoglycans, also contain structural determinants for apica...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1999-06-01 00:00:00
abstract::We depleted MAP4, a ubiquitously expressed microtubule (MT)-associated protein previously shown to be capable of stabilizing MTs, from HeLa cells by stably expressing antisense RNA. These HeLa-AS cells, in which the MAP4 level was decreased to 33% of the wild-type level, displayed decreased content of total tubulin (6...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1999-06-01 00:00:00
abstract::We have characterized precisely the cytokeratin expression pattern of sweat gland myoepithelial cells and have identified conditions for propagating this cell type and modulating its differentiation in culture. Rare, unstratified epithelioid colonies were identified in cultures initiated from several specimens of full...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1999-06-01 00:00:00
abstract::The evolutionary changes that occur in signal-mediated nuclear transport would be expected to reflect an increasing need to regulate nucleocytoplasmic exchanges as the complexity of organisms increases. This could involve changes in both the composition and structure of the pore complex, as well as the cytosolic facto...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1999-06-01 00:00:00
abstract::Waves of chemotactic movement during the early phase of aggregation in Dictyostelium discoideum are of 2 kinds, concentric waves produced by cells that emit cyclic AMP signals spontaneously, and spirals generated by excitations relayed continuously around loops of excitable cells. The period of a spiral wave is the ti...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1976-12-01 00:00:00
abstract::In the course of this study more than 20 proteins have been isolated from the larval cuticle of Manduca sexta. Synthesis, secretion, transport and accumulation of four particular proteins, representative members of four characteristic groups, were followed during metamorphosis by immunoblot and immuncytochemical metho...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1999-07-01 00:00:00
abstract::Recent studies have suggested a correlation between increased expression of specific beta-tubulin isotypes and paclitaxel resistance in drug-selected cell lines. In an attempt to establish a causal link, we have transfected Chinese hamster ovary cells with cDNAs encoding epitope-tagged class I, II, and IVb beta-tubuli...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1999-07-01 00:00:00
abstract::We have performed a real time analysis of fluorescence-tagged vesicle and mitochondria movement in living CHO cells transfected with microtubule-associated protein tau or its microtubule-binding domain. tau does not alter the speed of moving vesicles, but it affects the frequencies of attachment and detachment to the ...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1999-07-01 00:00:00
abstract::Previous studies indicate that a zinc- and phorbol ester-binding factor is necessary for in vitro endosome fusion and for the effect of Rab5 on endosome fusion. Rab5 is a small GTPase that regulates membrane fusion between early endosomes derived from either receptor-mediated endocytosis or fluid-phase endocytosis. In...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1999-08-01 00:00:00
abstract::Morphological examination of the highly polarized protozoan parasite Toxoplasma gondii suggests that secretory traffic in this organism progresses from the endoplasmic reticulum to the Golgi apparatus using the nuclear envelope as an intermediate compartment. While the endoplasmic reticulum is predominantly located ne...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1999-08-01 00:00:00
abstract::The contribution of three actin cross-linking proteins, alpha-actinin (alphaA), gelation factor (ABP-120), and the 34 kDa actin-bundling protein to cellular functions has been studied in three single mutant (alphaA-, 120-, and 34-) and three double mutant (alphaA-/120-, 34-/alphaA-, 34-/120-) strains of Dictyostelium ...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1999-08-01 00:00:00
abstract::A model is proposed for an amplification step in chemotactically sensitive cells or growth cones that accounts for their extraordinary directional sensitivity. It is assumed that cells have an intrinsic pattern forming system that generates the signals for extension of filopods and lamellipods. An external signal such...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1999-09-01 00:00:00
abstract::Rat hepatocytes adherent to a rigid film of type I collagen will spread and enter S phase, while those attached to collagen gel or a dried collagen substrate remain round and quiescent. The current studies were initiated to determine the mechanism by which these different substrates differentially influence cell cycle...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1999-09-01 00:00:00
abstract::Using autoimmune antibodies from a patient with primary biliary cirrhosis we have identified a 68 kDa nuclear envelope protein, termed PBC68. This protein is co-precipitated with a 98 kDa and a 250 kDa polypeptide and is distinct from the nuclear lamins. Immunostaining of digitonin-permeabilized cells indicates that P...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1999-09-01 00:00:00
abstract::Elastic extracellular matrix protein tenascin-C (TN) has very restricted expression in normal tissues, but is expressed in large quantities during embryogenesis and hyperplastic processes. To examine the importance of mechanical stress on the regulation of TN expression in vivo, the effects of various mechanical loadi...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1999-09-01 00:00:00
abstract::Syndecan-4 is a widely expressed transmembrane heparan sulfate proteoglycan which localizes to focal adhesions. Previous studies showed that the syndecan-4 cytoplasmic domain can associate with and potentiate the activity of protein kinase C, which is required for focal adhesion formation. To examine further the role ...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1999-10-01 00:00:00
abstract::The Rel/NF-kappaB family of transcription factors and regulators has so far only been described in vertebrates and arthropods, where they mediate responses to many extracellular signals. No counterparts of genes coding for such proteins have been identified in the Caenorhabditis elegans genome and no NF-kappaB activit...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1999-10-01 00:00:00
abstract::The transcription termination factor TTF-1 exerts two functions in ribosomal gene (rDNA) transcription: facilitating initiation and mediating termination of transcription. Using HeLa cells, we show that TTF-1 protein is colocalized with the active transcription machinery in the nucleolus and also with the inactive mac...
journal_title:Journal of cell science
pub_type: 杂志文章
doi:
更新日期:1999-10-01 00:00:00