bluuebunny/crossref_metadata_2025_split huggingface dataset:
Signal transduction pathways involved in the expression of the uridine diphosphoglucose pyrophosphorylase gene of Dictyostelium discoideum
Authors: Haribabu Bodduluri , Pavlovic Jovan , Bodduluri Sobha R. , Doody Jacqueline F. , Ortiz Benjamin D. , Mullings Suzan , Moon Byoung , Dottin Robert P. 
Published: May 2005

AbstractThe uridine diphosphoglucose pyrophosphorylase (UDPGP1) gene of Dictyostelium discoideum is an excellent marker to study the pathways that control the expression of genes during development. We have previously shown that the UDPGP1 gene is regulated by exogenous cAMP acting on cell‐surface cAMP receptors. Various steps in the signal transduction pathway between receptor stimulation and the induction of the gene can now be studied. Induction does not require the synthesis of intracellular cAMP, but does require new protein synthesis. By deletion and transformation with altered genes, two cis‐acting sequences that are required for UDPGP1 expression have been identified. A GC‐rich palindromic sequence located between −410 and −374 is essential for induction of the gene by extracellular cAMP, but not for its basal expression. A sequence element located between −374 and −337 is required for any basal expression of this gene. When the polarity of the palindromic sequence was reversed such that it resembled the H2K enhancer element, the gene could still be induced by exogenous cAMP. Two DNA binding activities were detected in gel mobility shift assays using a fragment containing both of the regulatory sequence elements of UDPGP1 gene. Transformation with a vector that resulted in the synthesis of anti‐sense UDPGP1 RNA led to almost total elimination of the enzyme antigen and no detectable enzyme activity. However, these transformants developed normally, indicating that either UDPGP is not required for development or residual synthesis of UDPGP may be sufficient for normal development.
Evidence for the presence of a growth factor in Dictyostelium discoideum
Authors: Whitbread John A. , Sims Matthew , Katz Eugene R. 
Published: May 2005

AbstractPolypeptide hormones, recognized for their ability to regulate cell growth and differentiation, have been classified as growth factors. These growth factors have been extensively described in higher eukaryotic organisms and cell lines [Hedin and Westermark, Cell 37:9–20, 1984]. Here we report the identification and partial characterization of a putative growth factor present in vegetative amoebae of the cellular slime mold Dictyostelium discoideum. A mutant was selected and found to be temperature sensitive due to the absence of an extracellular protein suggestive of a growth factor. The putative growth factor (DGF) is a protein resistant to both heat and strong detergent treatment but sensitive to reducing agents. The physiological significance of DGF is as yet unknown. DGF is of interest both in relation to understanding the events which control cell proliferation in Dictyostelium and in its relationship to other known growth factors.
Sequence elements that affect mRNA translational activity in developing Dictyostelium cells
Authors: Steel Laura F. , Jacobson Allan 
Published: May 2005

AbstractPost‐transcriptional controls, including changes in both mRNA translational activity and stability, play an important role in the regulation of ribosomal protein gene expression in developing Dictyostelium discoideum cells. Previously we have shown that the mechanisms which regulate the translational activity of the r‐protein mRNAs operate at the level of translational initiation and do not involve changes in polyadenylation or capping. By analysing the translational behavior of chimeric and mutant mRNAs in transformed cells, we have now been able to localize the determinants of translational activity of one of the r‐protein mRNAs to the 5′‐untranslated region. Although this and other r‐protein mRNAs differ strikingly from the Dictyostelium consensus in the region of the initiator AUG codon, we find that improving the match to that consensus does not increase the translational activity of the message in developing cells. Current experiments are designed to determine whether translational regulation is mediated by strong interactions with specific inhibitors or by weak interactions with translational initiation factors.
Developmental protein synthesis is required for the transcription of Dictyostelium prespore genes
Authors: Benedict M. A. , Desilver D. A. , Pelletier D. E. , Pentz W. H. , Ratner D. I. 
Published: May 2005

AbstractIt has been established previ‐ ously that the maintenance of expression of pre‐spore‐specific genes of Dictyostelium discoideum is prevented by the translational inhibitor cyclohex‐ imide. The drug had no effect upon the level of transcripts of the other genes examined, prestalk‐specific or cell type‐nonspecific. However, the interpretation of this result is open to question, because of possible nonspecific effects of cyclo‐heximide. We have now characterized the cellular specificity and temporal profiles of mRNA accumu‐ lation of additional Dictyostelium cDNA clones, and have examined other inhibitors of in vivo protein synthesis. Four structurally and mechanistically distinct translational inhibitors each prevented the reaccumulation of prespore transcripts in cyclic AMP‐primed, disaggregated amoebae. These results establish the importance of developmental protein synthesis in the accumulation of prespore gene transcripts. Nuclear run‐on transcription assays were used to learn whether protein synthesis is required primarily for mRNA synthesis or transcript stability. A transcriptional time course first demonstrated that the abundance of these cell‐specific transcripts during development mirrors their rates of synthesis. Significantly, the protein synthesis requirement of the prespore genes examined also occurs at the level of mRNA transcription, implying the existence of one or more developmentally regulated transcriptional activators.
Dictyostelium discoideum gene family contains a long internal amino acid repeat
Authors: Ennis Herbert L. , Giorda Roberto , Ohmachi Tetsuo , Shaw David R. , Blume John E. 
Published: May 2005

AbstractTwo different cDNA clones denoted pT0270‐6 and pT0270‐11 represent two mRNAs that are developmentally regulated during spore germination in Dictyosteliurn discoideum. The respective mRNAs are found only during early germination and are not present in other stages of growth or multicellular development. Four different genomic clones that hybridize to sequences that are common to both of the 270 cDNA clones were isolated from Dictyostelium libraries and se‐ quenced. Two are the genes for the two cDNAs, and the other two represent genes that do not seem to be transcribed. All four genomic se‐ quences possess a very unusual internal feature in the deduced protein sequences composed of a monotonous repeat of the tetrapeptide threonine‐ glutamic acid‐threonine‐proline. The other portions of the proteins have no homology among them‐ selves. The deduced protein corresponding to the 270‐6 gene is very similar to avocado (Persea arnericana) cellulase. Since cellulose in the spore wall has to be digested during spore germination this suggests that this protein may function as an endo‐( 1,4)‐beta‐D‐glucanase during germination.
Kinase activity and genetic characterization of a growth related antigen of Drosophila
Authors: Bedian Vahe , Jungklaus Christine E. , Cardoza Lisa , Kalm Laurence Von 
Published: May 2005

AbstractThe Drosophila developmental antigen recognized by the monoclonal antibody F7D6 is expressed in dividing embryonic and imaginal cells but is lost from all differentiating fissues except electrogenic cells of the nervous system and spontaneously contracting muscles. The 63 kDa antigen is associated with the inner surface of plasma membranes and is expressed in several classes of fumorous mutants of Drosophila. The monoclonal antibody was used for immunoprecip‐itating the antigen for biochemical characterization and for screening expression vector cDNA libraries. Here we report that this oncodevelopmental antigen is a phosphoprotein and a serine‐threonine specific protein kinase. A 1.6 kb cDNA isolated by immunological screening of an ovarian library hybridized to a single band on polytene chromosomes, localizing the gene to 72F on the left arm of the third chromosome. Immunofluorescence assays of deficiency stocks in the region confirmed the location of the gene and identity of the cDNA clone, and mapped the gene between the left breakpoints of Df(3L) st1100.62 and Df(3L) sti7, i.e., between 72F3–7 and 73A1–2. The biochemical and genetic properties indicate that this is a novel growth‐related kinase of Drosophila.
Despite expression in embryonic visceral mesoderm, H2.0 is not essential for Drosophila visceral muscle morphogenesis
Authors: Barad Mark , Erlebacher Adrian , McGinnis William 
Published: May 2005

AbstractH2.0, a homeobox gene identified by homology to the Sex combs reduced homeobox of Drosophila, is expressed in all the cellular precursors of the visceral musculature. By analogy to the essential function of most other known homeobox genes in determining the fate of cells where they are expressed, we hypothesized that mutation of H2.0 would disrupt gut muscle development. In this paper, we show that a small deletion, which eliminates H2.0, has no detectable effect on normal gut morphogenesis, visceral muscle actin organization, or larval peristalsis.
Regulatory elements near the Drosophila hsp 22 gene required for ecdysterone and heat shock induction
Authors: Rudolph Karen , Morganelli Christine , Berger Edward M. 
Published: May 2005

AbstractA transient expression assay was used to localize cis‐acting DNA regulatory elements near the Drosophila heat shock protein (hsp) 22 gene, that are involved in heat shock expression and in ecdysterone‐induced expression. The results identify a region between positions −320 and −232 that is essential for ecdysterone control, but not for heat‐induced expression, and a sequence between −199 and −56, which, when deleted, leads to the loss of heat shock induction. To investigate the function of these DNA sequences, transfection‐competition experiments were carried out. The evidence suggests that the DNA regulatory sequences identified by transient expression studies contain binding sites for transacting transcription factors.
Characterization and complementation analysis of sporogenous mutants of Dictyostelium discoideum
Authors: Sadiq May F. , Town Christopher D. 
Published: May 2005

AbstractSporogenous mutants of the cellular slime mold Dictyostelium discoideum are defined as mutants which are able to undergo terminal differentiation into spores in monolayer cultures in the presence of millimolar amounts of exogenous cyclic AMP. We describe the morphological development and cellular differentiation of a collection of 12 independently isolated sporogenous mutants of strain V12 M2. All mutants develop more rapidly than do wild‐type at an air‐water interface, display aberrant morphogenesis, and show overt spore and stalk differentiation as soon as 4 hr after starvation. All mutants differentiate in submerged monolayer culture in the presence of cAMP into variable proportions of spores and stalk cells. A number of the mutants also form both stalk cells and spores in submerged culture in the absence of exogenous cAMP. The spores formed by many of the mutants have a greatly reduced viability. Using parasexual genetics, we have found that two of the 12 mutants analyzed are dominant to wild‐type and the remaining ten fall into a minimum of four complementation groups, the overall analysis thus yielding a minimum of four and a maximum of seven complementation groups. Intracellular cAMP levels in vegetative cells are significantly elevated in the two dominant mutants but are similar to wild type in all the other mutants.
Effect of prenatal ethanol exposure on postnatal neural gene expression in the rat
Authors: Naus Christian C. G. , Bechberger John F. 
Published: May 2005

AbstractTo examine the effects of ethanol exposure on neural development, pregnant rats were fed a liquid diet in which 37.5% of the total caloric content was ethanol‐derived. The developmental appearance of the messenger RNAs coding for preprosomatostatin, glial fibrillary acidic protein, and proteolipid protein was examined by Northern blotting of total cellular RNA obtained from forebrain and hindbrain at various times after birth. In general, there was a delay in the developmental pattern of appearance of these mRNAs which was most noticeable at the early postnatal times. These results suggest that the previously reported delay in neural maturation is reflected at the level of the gene expression.
Several testis‐expressed genes in the mouse t‐complex have expression differences between wild‐type and t‐mutant mice
Authors: Ha Haesook , Howard C. Alan , Yeom Young Il , Abe Kuniya , Uehara Hiroshi , Artzt Karen , Bennett Dorothea 
Published: May 2005

AbstractThe t‐complex of the mouse occupies the proximal half of chromosome 17 and cantains genes which have profound effects on spermatogenesis. Mutations of several loci in the t‐complex appear to interact to cause male sterility or transmission ratio distortion (TRD).By cDNA screening or chromosomal walking we have identified seven genes, which are expressed in the germ cells of testis and map to various regions of the t‐complex. These genes were named t‐complex testis‐expressed (Tctex) genes. An analysis of their expression patterns in testes from +/+, +/t, and t/t mice was done by in situ hybridization and by northern blotting. Six genes begin to be expressed at the pachytene stage: Three of them are more abundant at pachytene stage, while three others are more abundant at postmeiotic stages. One gene is expressed at all the stages of spermatogenesis. Interestingly, four Tctex genes show differences in the amount of transcript between wild‐type and t‐mutant testes. The chromosomal location and expression pattern imply that Tctex genes might be candidate genes for sterility or TRD.
Elevated paraquat resistance can be used as a bioassay for longevity in a genetically based long‐lived strain of Drosophila
Authors: Arking Robert , Buck Steven , Berrios Angela , Dwyer Susan , Baker George T. 
Published: May 2005

AbstractA long‐lived (L) strain of Drosophila melanogaster, derived from a normal‐lived (R) strain by artificial selection, has a significantly different adult longevity. Previous work has shown that (1) the two strains age in the same manner, (2) the major genes responsible for much of the L strain's extended longevity are located on the 3rd chromosome, and (3) the extended longevity phenotype is significantly modulated by the larval environment. In this report, we investigate the resistance of the L and R strains to the lethal effects of dietary paraquat. We show that, within the limitations of our described chromosomal and environmental manipulations, the extended longevity phenotype always accompanies the phenotype of elevated paraquat resistance. In addition, reversed selection applied to the L strain results in the simultaneous decrease of both life span and paraquat resistance. Thus, the presence or absence of the latter phenotype may be used as a bioassay for the presence or absence of the extended longevity phenotype, without any necessary implication of causality. Use of this bioassay should greatly speed up the genetic analysis of this system by allowing us to identify long‐lived animals at a young age. Finally, we show that the age‐related loss of elevated paraquat resistance in both strains precedes all the other age‐related functional decrements which we have previously noted in this system.
Morphological abnormalities, neonatal mortality, and reproductive abnormalities in mice transgenic for diphtheria toxin genes that are driven by the promoter for adipocyte lipid binding protein
Authors: Homanics Gregg E. 
Published: May 2005

AbstractTransgenic mice were used in an experiment that was designed to serve as a model of a possible approach to reducing the amount of carcass fat in meat animals. The objective was to reduce the number of adipocytes in transgenic mice thereby restricting the capacity to accumulate lipid. Our approach employed the technique of genetic ablation. The promoter for the adipocyte lipid binding protein gene was used in an attempt to direct expression of diphtheria toxin genes specifically to adipocytes. Three diphtheria toxin genes were used; they encode, respectively, an extremely cytotoxic wild type toxin, a less toxic attenuated toxin, and a nonfunctional toxin. While it was not possible to accurately assess effects of the transgenes on lipid accumulation, several informative observations were noted. A large percentage of transgenic founder mice that harbor either wild type or attenuated toxin genes are morphologically abnormal, die as neonates, or exhibit reproductive abnormalities including sterility or failure to transmit the transgene to offspring. In contrast, mice that harbor the nonfunctional toxin gene or are nontransgenic rarely have these same abnormalities. These results suggest that the trans‐genic mice are expressing the transgenes in cells other than adipocytes and that the aberrant production of functional toxin is responsible for the congenital abnormalities. The production of morphological and reproductive abnormalities in transgenic animals should be useful for investigating normal developmental processes.
Expression of glucose phosphate isomerase in interspecific hybrid (Mus musculus × Mus caroli)
Authors: West John D. , Ansell John D. , Flockhart Jean H. 
Published: May 2005

AbstractHybrid Mus musculus × Mus caroli embryos were produced by inseminating M. musculus (C57BL/Ola Ws) females with M. caroli sperm. Control M. caroli embryos developed more rapidly than did control M. musculus embryos and implanted approximately 1 day earlier. At 1 1/2 days, both the hybrid embryos and those of the maternal species (M. musculus) had cleaved to the 2‐cell stage. By 2 1/2 days some of the hybrids were retarded compared to M. musculus, and by 3½ days most were lagging behind. This is consistent with the idea that the rate of development of hybrid embryos declines once it becomes dependent on embryo‐coded gene products.We have used this difference in rate of preim‐plantation development, between hybrid and M. musculus embryos, to try to determine whether the activation of embryonic Gpi‐1s genes, that encode glucose phosphate isomerase (GPI‐1), is age‐related or stage‐related. In control M. musculus embryos (both mated and Al groups), the GPI‐1AB and GPI‐1A allozyme, indicative of paternal gene expression, were detected in 7 of 9 samples of 3 1/2‐day compacted morula stage embryos and were seen in all 19 samples of 31/2‐day blastocysts. In hybrid embryos, these allozymes were detected 1 day later. They were not detected in any 31/2‐day samples (12 samples of compacted morulae) but were consistently detected at 4½ days (4 samples of blastocysts and 2 samples of uncompacted morulae). Our interpretation of the results is that gene activation in hybrid embryos is stage‐specific, rather than age‐specific, and probably begins around the 8‐cell stage, with detectable levels of enzyme accumulating later. Analysis of GPI‐1 elec‐trophoresis indicated that both the paternal (M. caroli) and maternal (M. musculus) Gpi‐1s alleles were equally expressed in hybrid embryos and that the paternally derived allele was not activated before the maternally derived allele. © 1992 Wiley‐Liss, Inc.
Catalase and superoxide dismutase gene expression and distribution during stem development in maize
Authors: Acevedo Alberto , Scandalios John G. 
Published: May 2005

AbstractThe temporal and spatial patterns of expression of the Cat and Sod genes encoding the multiple catalases and superoxide dismutases in maize have been examined throughout stem development. Three stages of stem development have been defined based upon catalase activity profiles and stem internode elongation. At stage 1, catalase activity is low and internodes remain short; at stage 2, catalase activity dramatically increases and internodes rapidly elongate; and at stage 3, catalase activity decreases to levels intermediate to stage 1 and 2, and internode elongation ceases. Zymogram analysis and immunoassays show that only the CAT‐3 catalase isozyme is present in the stem, even though both Cat1 and Cat3 mRNAs accumulate throughout stem development. Cat2 mRNA is not detectable in the developing stem. In full‐grown stems catalase is localized primarily in the sclerenchyma beneath the epidermis and around the vascular bundles and may possibly play a role in lignification. Unlike catalase, all the superoxide dismutase (SOD) isozymes and transcripts are present in the developing stem. Thus, these two major antioxidant gene‐enzyme systems show differential patterns of expression during stem development in maize. © 1992 Wiley‐Liss, Inc.
Distinct developmental regulatory mechanisms for two members of the aldolase gene family
Authors: Maine Ann B. , Ciejek‐Baez Elena 
Published: May 2005

AbstractThe aldolase isozyme family is composed of three members, A, B, and C, which are encoded by separate genes. The proteins are expressed in a tissue‐restricted manner during development and in the adult. To elucidate the regulation of aldolose mRNA in the mouse liver, we analyzed its expression by a number of methods including Northern blot, RNA dot blot, and nuclear run‐on assays. Our experiments demonstrate that the expression of aldolase A in the liver is primarily regulated by post‐transcriptional control. In contrast, we found that changes in the level of aldolase B mRNA are due to changes in the rate of initiation of transcription. In addition, we examined the regulation of aldolase expression in the adult kidney. We found that although the kidney has eight times more aldolase B than the live, the rate of initiation of transcription is similar in both tissues. Also, the rate of initiation of transcription of aldolase A is the same in the adult kidney and liver although there is 40 times more steady state aldolase A mRNA in the kidney than in the liver. © 1992 Wiley‐Liss, Inc.
Developmental analysis of the cell recognition mechanism in the ciliate Euplotes raikovi
Authors: Luporini Pierangelo , Miceli Cristina , Ortenzi Claudio , Vallesi Adriana 
Published: May 2005

AbstractEuplotes raikovi, like other ciliates, passes through a postconjugal immaturity, operatively identified by an apparent cell inability to form mating pairs under experimental conditions that are the same as those used for inducing mating at maturity. In cells homozygous for the gene mat‐2, which controls the pheromone Er‐2, Er‐2 mRNA synthesis and mature Er‐2 secretion were shown to start from the very beginning of the life cycle and continue throughout immaturity, although to extents estimated to be 5‐ to 10‐fold lower than at maturity. In addition, experiments of 125 I‐Er‐2 binding and crosslinking provided evidence that autocrine pheromone‐binding sites, showing values of the dissociation constant of the order of 10−9 M, are on the surface of immature cells. The number of these sites per cell was estimated to increase from less than 106 per cell of 5–7 fissions of age, to about 16 × 106 at maturity. These results were taken to suggest that a pheromone‐receptor production is stimulated during immaturity by autocrine pheromone binding to cells and that this production might be essential for the development of a pheromone‐receptor density high enough to transform the cell from “immature” to “adult,” that is competent to respond as well to pheromones of conspecific, genetically different cells. © 1992 Wiley‐Liss, Inc.