bluuebunny/crossref_metadata_2025_split huggingface dataset:
Butyrate induces expression of transfected human fetal and endogenous mouse embryonic globin genes in GM 979 erythroleukemia cells
Authors: Zhang Jun‐Wu , Raich Natacha , Enver Tariq , Anagnou Nicholas P. , Stamatoyannopoulos George 
Published: May 2005

AbstractWe have analyzed the expression of endogenous murine genes and of transfected human fetal Aγ globin gene in GM 979, a mouse erythroleukemia line which produces adult as well as embryonic globins. Optimal induction of the endogenous murine adult globin genes was obtained with DMSO or HMBA while the ϵy and βh1 embryonic genes were preferentially induced by butyrate. Similarly, the transferred human Aγ globin gene was preferentially induced by butyrate. These results as well as previous observations in vivo or in erythroid cell cultures suggest that butyrate preferentially induces the expression of fetal globin genes.
Direct gene transfer to protoplasts: Fate of the transferred genes
Authors: Saul Michael W. , Potrykus Ingo 
Published: May 2005

AbstractDirect gene transfer to protoplasts is one of several methods developed for the production of transgenic plants. This method utilizes the efficient uptake of DNA from the surrounding medium by protoplasts (cell wall‐less plant cells). Where a suitable protoplast system exists large numbers of transformant clones can be efficiently produced and often regenerated to normal fertile plants. This review concentrates on the fate of the DNA which is taken up into the protoplasts. Particular emphasis is given to the factors which can influence the integration and form of the transferred DNA, the expression of transferred genes, and the inheritance in further generations of those genes. The information available suggests (1) that DNA is taken up by a large proportion of the cells in a transformation mixture, (2) that this DNA forms complexes sometimes involving carrier DNA, (3) that fewer cells actually take up DNA into the nucleus, and (4) that the complex may be rearranged and/or amplified and then integrated into the genome. If the DNA is arranged in such a way that a gene can be expressed it does so in a normal manner and is stably inherited both mitotically and meiotically.
Cell cycle‐regulated gene expression in transgenic plant cells
Authors: Kawata Takefumi , Nakayama Takuya , Ohtsubo Norihiro , Tabata Tetsuya , Iwabuchi Masaki 
Published: May 2005

AbstractA majority of histone genes are expressed in the S phase during the cell cycle. Using the gene expression system of transformed sunflower cells into which wheat histone H3 gene was introduced by the Ti‐plasmid gene transfer technique, we determined three cis‐acting control sequences (hexameric, octameric, and nonameric motifs) which seemed to confer the S‐phase‐specific transcription of wheat histone genes. Furthermore, as candidates for regulatory transcription factors, three nuclear DNA‐binding proteins HBP‐la, HBP‐lb, and HBP‐2 that interact with the hexameric and nonameric motifs were identified. The structural analysis of the cDNA of HBP‐la revealed that a nuclear protein has the leucine‐zipper structure and a DNA‐binding motif. The hexameric motif in the H3 gene was also seen in cauliflower mosaic virus 35S (CaMV 35S) promoter and shown to function as a regulatory element of this promoter. The wheat HBP‐1b can interact with the hexameric motif of the CaMV 35S promoter. Much attention has been paid to the significance of the hexameric sequences within the H3 and CaMV 35S promoters and the DNA‐binding proteins HBP‐la and HBP‐lb.
Analysis of coat‐color patterns in aggregation chimeras between BALB/cA and C3H/HeN mice with special reference to migratory patterns and clone number of epidermal melanoblasts
Authors: Tachi Chikashi , Yokoyama Minesuke , Kojima Hiroko 
Published: May 2005

AbstractChimeras provide unique opportunities to study interactions between the phenotypically similar but genotypically allogeneic cell populations during embryogenesis in vivo. From the quantitative analysis of coat‐color patterns in C3H/HeN↔BALB/cA chimeras, a model was proposed stating that the aggregability of the C3H/ HeN‐derived melanoblasts in the chimeras was inversely related to the ratio between the mean free path of the epidermal melanoblasts in the normal C3H/He N mouse and that in the chimeras. As a corollary, the possibility was suggested that during the migration of melanoblasts, mechanisms identical with or similar to contact inhibition of movement might operate after collision between the isogeneic, but not between the allogeneic melanoblasts. With regard to the number of melanoblast clones in the trunk region of the mouse, the present series of analyses yielded the value of 24–28 arranged unilaterally; the value closely approximated the number of the somites in that region and provided further support for the proposition made earlier by Tachi [Dev Genet 9:121–154, 1988; “Development of Preimplantation Embryos and Their Environment.” New York: Alan R. Liss, Inc., 1989, pp 263–274].
Heat shock causes the collapse of the intermediate filament cytoskeleton in Drosophila embryos
Authors: Walter Marika F. , Biessmann Harald , Petersen Nancy S. 
Published: May 2005

AbstractHeat shock has a dramatic effect on the organization of the cytoplasm, causing the intermediate filament cytoskeleton to aggregate of the nucleus. This has previously been shown in cultured Drosophila and mammalian cells. In this paper we analyze the heat lability of the intermediate filament cytoskeleton in early Drosophila embryos by indirect immunofluorescence. At all stages of embryogenesis tested, the intermediatefilamentcytoskeleton, which is maternally provided, is severely disturbed by 30 min heat shock at 37°C. After the nuclei have migrated to the subcortical cytoplasm, it collapses around them. Nuclei in all heat‐shocked embryos are considerably enlarged and become displaced. Embryos before cellular blastoderm stage, in which heat shock protein synthesis is not inducible, are irreversibly arrested in development by heat shock. Embryos at or after cellular blastoderm, which do synthesize heat shock proteins in response to stress, are also immediately arrested in development but continue development when returned to 25°C. We discuss the possibility that cytoplasmic events such as the intermediate filament cytoskeleton rearrangement may be involved in heat shock‐mediated phenocopy induction.
Cell type specific expression of a CaMV 35S‐GUS gene in transgenic soybean plants
Authors: Yang Ning‐Sun , Christou Paul 
Published: May 2005

AbstractA number of independently derived transgenic soybean plants expressing a chimeric β‐glucuronidase (GUS) gene under the control of the 355 CaMV promoter and a nopaline synthase polyadenylation signal were recovered using direct DNA transfer via electric discharge particle acceleration. Expression of GUS in R, plants was localized using thin tissue sections. Many tissue types expressed GUS at various levels. Pericycle cells in root, parenchyma cells in xylem, and phloem tissues of stem and leaf had high levels of enzyme activity. Procambium, phloem, and cortex cells in root, vascular cambium cells in stem, and the majority of cortex cells in leaf midrib, expressed low or no GUS activity. Intermediate levels of GUS activity were detected in leaf mesophyll cells, certain ground tissue cells in stem and leaf midrib, and in trichome and epidermal guard cells. Thus, we conclude that the 35S CaMV promoter is cell‐type specific and is developmentally regulated in soybean.
Arabidopsis: Sensitivity of growth to high temperature
Authors: Binelli Giorgio , Mascarenhas Joseph P. 
Published: May 2005

AbstractArabidopsis thaliana seedlings as measured by an electrolyte leakage assay, have been found to be extremely sensitive to high temperature stress as compared to a high temperature tolerant variety (Tracy) of soybean. Over 50% ion leakage occurred in Arabidopsis leaves during a 15‐minute exposure to 50°C, indicating a heat killing time of less than 15 minutes. In contrast, the heat killing time for soybean at 50°C was over five times longer. When soybean or Arabidopsis seedlings in culture plates were exposed to 37°C for 2 hours and then returned to 23°C, they suffered no apparent short‐term or long‐term damage. Soybean seedlings given a 42°C, treatment for 2 hours also showed no damage. Arabidopsis seedlings after a 42°C treatment for 2 hours showed no apparent immediate damage, but 48 hours after return to 23°C severe damage symptoms were visible and after 96 hours all the seedlings were dead. Both soybean and Arabidopsis seedlings synthesize heat shock proteins (hsps) when exposed to 42°C for 2 hours. The hsps synthesized are of similar molecular weights, although the relative abundances of the different size classes are very different in the two plants. Even though hsps are produced in Arabidopsis seedlings after a 2 hour exposure to 42°C their presence is not sufficient for the seedlings to recover from the effects of rhe heat shock when returned to 23°C. Our results show that Arabidopsis has a heat sensitive genotype. This along with its other characteristics should make it a good model system in which to assay in transgenic plants, the functions of homologous and heterologous genes that might be candidates for determining heat tolerance in plants.
Characterization of IMP‐E3, A gene active during imaginal disc morphogenesis in Drosophila melanogaster
Authors: Moore John T. , Fristrom Dianne , Hammonds Ann S. , Fristrom James W. 
Published: May 2005

AbstractThe steroid hormone 20‐hydroxyecdysone (20‐HE) induces imcainol discs to form adult appendages in Drosophila. We have isolated a set of six ecdysone‐responsive genes that apparently encode disc cell‐surface or secreted proteins. Transcripts from one of these genes, IMP‐E3, accumulate rapidly within 1–2 h in response to hormone. Developmentally,IMP‐E3 transcripts reach maximum levels during the first stages of metamorphosis (white prepupae, WPP) and are primarily limited to imaginal tissues. Transcripts are also present during embryogenesis (0–3 h and 12–18 h). Two different‐sized transcripts (1.2 and 1.4 kb) result from differential polyadenylation, with the larger transcript predominating in WPP. The conceptual IMP‐E3 protein contains a signal peptide, an RGD sequence, and a potential glycosylphosphatidylinositol anchor. We speculate that the protein provides a transient cue important for imaginal disc morphogenesis.
Molecular and developmental analyses of the protein encoded by the Drosophila gene Ectodermal
Authors: Raha Debasish , Nguyen Quan Dong , Garen Alan 
Published: May 2005

AbstractThe Drosophila gene ectodermal (ect, located at 67D8‐10 on chromosome 3) is expressed for a short period at mid‐embryogenesis in all ectodermally derived tissues except the nervous system. During this stage the tissues involved form tubular structures by a process of invagination followed by cell fusion. Here we report the sequence of the ect protein as deduced from the longest ORF (280 codons) of an ect cDNA. The principal molecular features of the ect protein are: (1) a consensus leader sequence for targeting to the rough ER; (2) a central domain containing a remarkably high density of acidic residues arranged in large clusters separated by smaller clusters of hydrophobic residues; (3) a consensus nuclear‐targeting sequence near the C‐terminus; (4) a single tyrosine residue located at a potential tyrosine‐sulfation site. The antibody staining pattern of the ect protein corresponds to the in situ hybridization pattern of the transcript. A possible role for the ect protein in the complex process of fubular formation that occurs in embryonic ectodermal tissues is discussed.
In situ hybridization studies on murine catalase mRNA expression during embryonic development
Authors: Reimer D. L. , Singh S. M. 
Published: May 2005

AbstractIn situ hybridization using nucleic acid probes was used to detect cell‐ and tissue‐specific transcript(s) of embryonic genes during development and differentiation. This highly sensitive technique has the potential to provide valuable information on the regulation of low‐abundance housekeeping genes during development. We have determined the experimental conditions required to detect the catalase message in adult mouse liver. Catalase effects the breakdown of H2O2 to O2 and H2O and offers protection against the toxic effects of oxygen radicals. We used a cloned 550 bp BamHI‐Pstl fragment from a mouse catalase cDNA (pMCT‐1) to generate 35S‐labeled sense and antisense riboprobes. The experimental conditions used were sensitive enough to quantitate the abundance of silver grains generated by the antisense riboprobe on the adult liver, a tissue known to be positive for this message. The hybridization protocol was applied to serial sections of 13‐ and 18‐day‐old mouse embryos. The results suggest that the catalase expression in the liver and brain begins with somite formation and increases with development and differentiation. On the other hand, this message appears to be absent in mesenchyme, particularly in day 13 embryos. The message in positive tissues appears evenly distributed throughout the cell. The observed expression of the catalase message in the adult liver is approximately six times that in the embryonic liver. It is compatible with the enzyme activity results and emphasizes the sensitivity of the in situ hybridization method (over northern blot, etc.) used in this study.
Cell‐cell adhesion and morphogenesis in Dictyostelium discoideum
Authors: Siu Chi‐Hung , Kamboj Rajender K. 
Published: May 2005

AbstractDuring development of Dictyostelium discoideum, cells acquire EDTA‐resistant cell‐cell adhesion at the aggregation stage. The EDTA‐resistant cell binding activity is associated with a cell surface glycoprotein of Mr 80,000 (gp80), which mediates cell‐cell binding via ho‐mophilic interaction. Analysis of the structure of gp80 deduced from cDNA sequence reveals the presence of three internally homologous segments in the NH2‐terminal domain, which also contains regions with homology to the neural cell adhesion molecule. Secondary structure predictions show an abundance of β‐structures and very few α‐helices. This is confirmed by circular dichroism measurements. It is likely that the homologous segments are organized into globular structures, extended from the cell surface by a Pro‐rich stalk domain. The cell binding activity of gp80 resides within the first globular repeat of the NH2‐terminal domain and has been mapped to a 51 amino acid region between Val123 and Leu 173. Synthetic oligopeptides corresponding to sequences within this region have been prepared and assayed for their ability to bind to cell surface gp80. Results lead to identification of the homophilic binding site to an octapeptide sequence within this region. Synthetic peptides containing this octapeptide sequence and univalent antibodies directed against this site block the formation of organized cell streams during aggregation. Although cell aggregates are eventually formed, most fail to undergo further development to give rise to slugs and fruiting bodies, indicating that cell‐cell adhesion involving gp80 is an important step in normal morphogenesis.
Regulation of the anterior‐like cell state by Ammonia in Dictyostelium discoideum
Authors: Nathan Feit Ira , Bonner John Tyler , Suthers Hannah B. 
Published: May 2005

AbstractAmmonia appears to be an important regulatory signal for several aspects of the Dictyostelium life cycle. The postulated role of ammonia in the determination of the prespore pathway in cells of the slug stage has led us to examine the effect of ammonia on the prestalk/prespore ratio of migrating slugs. In the presence of 10−3 M ammonium chloride, the volume of the prestalk region decreases by 40.8%. The kinetics of the process make it unlikely that this is due to a shift in the differentiation pathway. A test of the hypothesis that the decrease in volume of the prestalk region is due to the conversion of prestalk cells to anterior‐like cells shows that the percent of anterior‐like cells in the posterior region increases by the amount predicted by the hypothesis. This suggests that ammonia may be the molecular signal, produced by the tip, that prevents anterior‐like cells from chemotactically migrating to the tip and thereby becoming anterior cells. The effect of enzymatic removal of ammonia from vitally stained migrating slugs is the appearance of a series of dark stripes beginning at the posterior end and progressing forward. We interpret this as a result of progressive removal of anterior‐like cells from tip dominance and essentially as the formation of new potential tips. Indeed, in a few cases one or even two of the stripes separate from the posterior of the cell mass and form small fruiting bodies. We consider the phenomenon of stripe formation further evidence that the tip acts on anterior‐like cells through ammonia.
Position‐Dependent regulation of the prestalk‐prespore pattern in Dictyostelium slugs
Authors: Pogge‐von Strandmann Ralph , Kay Robert R. 
Published: May 2005

AbstractIn classical transplantation experiments, we have attempted to distinguish between cell sorting and position‐dependent mechanisms of pattern formation during the regulation of amputated prespore regions of Dictyostelium slugs. Host and transplanted tissue were distinguished by prior labelling with 14C and 3H, and their distributions in the manipulated slugs were determined by double‐label scintillation counting of serial sections of the slugs. First, we showed that the regenerated prestalk region is formed predominantly from the anterior of a prespore isolate. This disproves extreme cell sorting models, which hold that the new prestalk cells arise at random in the prespore mass, before sorting to the prestalk zone. Second, we showed that a proportion of posterior cells, which are not normally recruited into the new prestalk region, can be recruited into it if they are transplanted into the anterior of the prespore isolate. Recruitment of these cells occurs only during the first hour of regulation. We believe that these experiments prove a position‐dependent mechanism of pattern formation during slug regulation. This in turn implies the existence of localized inductive signals in the regulating fragments. Although cell sorting occurs efficiently when cells are misplaced in the slug, it does not appear to play a major role in reforming the prestalk/prespore pattern.
Processing of neutral N‐linked oligosaccharides during early Dictyostelium discoideum development
Authors: Hobbs Lisa J. , Das O. Prem , Henderson Ellen J. 
Published: May 2005

AbstractWe have used metabolic radiolabeling with oligosaccharide precursors, coupled with subcellular fractionation, to examine the distribution of several classes of asparagine‐linked oligosaccharides during early development. In Dictyostelium, we have observed endoglycosidase H (endo H)‐sensitive structures with sizes corresponding to 10 (Hex10) and 11 (Hex11) hexose residues on the chitobiose core. Only Hex11 was detected as the major structure on fucosylated endo H‐resistant species. All Hex11 species cofractionated with plasma membrane and secreted glycoproteins, whereas Hex10 appeared to be confined to intracellular membrane and soluble glycoproteins. Sulfated species correlated with lysosomal and secreted fractions, and glucose residues were markedly depressed in Hex11 of secreted glycoproteins. Outer branch structural studies have revealed several components of the endo H‐sensitive species. Usingα‐mannosidase and β‐hexosaminidase as diagnostic tools, species elucidated thus far are: a structure with 10 mannoses, a structure with nine mannoses and an intersecting N‐acetylglucosamine, structures with three glucoses and seven or eight mannoses and several larger species with multiple blocks to digestion.
Formation of the Dictyostelium spore coat
Authors: West Christopher M. , Erdos Gregory W. 
Published: May 2005

AbstractThe spore coat forms as a rigid extracellular wall around each spore cell during culmination. Coats purified from germinated spores contain multiple protein species and an approximately equal mass of polysaccharide, consisting mostly of cellulose and a galactose/N‐acetyl‐galactosamine polysaccharide (GPS). All but the cellulose are prepackaged during prespore cell differentiation in a regulated secretory compartment, the prespore vesicle. The morphology of this compartment resembles an anastomosing, tubular network rather than a spherical vesicle. The molecules of the prespore vesicle are not uniformly mixed but are segregated into partially overlapping domains. Although lysosomal enzymes have been found in the prespore vesicle, this compartment does not function as a lysosome because it is not acidic, and a common antigen associated with acid hydrolases is found in another, acidic vesicle population. All the prespore vesicle profiles disappear at the time of appearance of their contents outside of the cell; this constitutes an early stage in spore coat formation, which can be detected both by microscopy and flow cytometry. As an electron‐dense layer, the future outer layer of the coat, condenses, cellulose can be found and is located immediately beneath this outer layer Certain proteins and the GPS become associated with either the outer or inner layers surrounding this middle cellulose layer. Assembly of the inner and outer layers occurs in part from a pool of glycoproteins that is shared between spores, and unincorporated molecules loosely reside in the interspore matrix, a location from which they can be easily washed away. When the glycosylation of several major protein species is disrupted by mutation, the coat is assembled, but differences are found in its porosity and the extractibility of certain proteins. In addition, the retention or loss of proteolytic fragments in the mutants indicates regions of spore coat proteins that are required for association with the coat. Comparative examination of the macrocyst demonstrates that patterns of molecular distributions are not conserved between the macrocyst and spore coats. Thus spore coat assembly is characterized by highly specific intermolecular interactions, leading to saturable associations of individual glycoproteins with specific layers and the exclusion of excess copies to the interspore space.
Multiple genes for cell surface cAMP receptors in Dictyostelium discoideum
Authors: Saxe Charles L. , Johnson Ronald , Devreotes Peter N. , Kimmel Alan R. 
Published: May 2005

AbstractWe have cloned and characterized three genes (CAR1, CAR2, CAR3) encoding potential cell surface, cyclic adenosine 3′:5′ monophosphate (AMP) receptors from Dictyostelium discoideum. The three proteins are predicted to be substantially similar in amino acid sequence throughout most of their transmembrane (TM) and loop domains but are distinctly different in their carboxyl terminal segments. In addition, all three genes possess an intron which interrupts an equivalent codon of TM3.CAR1 is expressed early in development when the cAMP relay system is being established. As development proceeds multiple size forms of CAR1 RNA are detected which apparently result from differences in their 5′‐untranslated regions. Late in development levels of CAR1 RNA decrease. In contrast, CAR2 encodes a single sized RNA which is expressed only during postaggregative development. CAR3 expression is ∼10% of CAR1 during early development, is maximal during tight aggregate formation but declines thereafter. Only one size class of CAR3 mRNA is detected throughout development.Because RNA for each of the three genes is present in postaggregative cells, it was of interest to determine the cell type distribution of each RNA. Gene‐specific probes were hybridized to RNAs isolated from cells of Percoll gradient‐enriched prespore and prestalk fractions and relative levels of hybridization compared. CAR1 and CAR3 show approximately the same pattern of accumulation; a 3–4 fold enrichment in prestalk cells. CAR2, however, is highly enriched in prestalk cells, more than 10 fold relative to prespore cells.