bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure and expression of the cAMP cell‐surface receptor
Authors: Saxe Charles L. , Klein Peter , Sun Tzeli J. , Kimmel Alan R. , Devreotes Peter N. 
Published: May 2005

AbstractUsing antibodies specific for the 3′, 5′‐cyclic AMP (cAMP) cell surface receptor of Dictyostelium discoideum, we have screened γgtll expression libraries and isolated a series of cDNAs derived from cAMP receptor mRNA during early development. The identity of the cDNA clones was verified by multiple criteria: (1) β‐galactosidase fusion proteins synthesized by isolated cDNA clones stain intensely with cAMP receptor directed antiserum, (2) these fusion proteins affinity purify antibodies specific for the cAMP receptor, (3) the cDNA probes hybridize to a 2 kb mRNA whose change in relative level of abundance during development parallels that of receptor mRNA as assayed by in vitro translation, (4) the 2 kb mRNA size equals that of receptor mRNA as determined by in vitro translation of size fractionated poly (A)+ RNA, and (5) RNA transcribed in vitro from cDNAs containing the entire protein‐coding region produces a polypeptide by in vitro translation with an apparent molecular weight in close agreement with that of nascent cAMP receptor protein produced by in vitro translation of cellular RNA.The DNA sequence predicts an open reading frame of 392 amino acids. The deduced amino acid sequence contains seven domains enriched in hydrophobic residues. A model is proposed in which the cAMP cell‐surface receptor traverses the lipid bilayer seven times in a pattern similar to that of other receptors, such as rhodopsin, which interact with G‐proteins. The structural similarities suggest a gene family of related surface receptors from such evolutionarily diverse species as Dictyostelium, yeast, and mammals.
Characterization of an unusual cAMP receptor and its related polypeptides in Dictyostelium discoideum
Authors: Tsang Adrian , Grant Caroline , Kay Carolyn , Bain Gerard , Greenwood Michael , Noce Toshiaki , Tasaka Masao 
Published: May 2005

AbstractSeveral lines of evidence indicate that cAMP modulates developmental gene activity via cell‐surface receptors. We describe here a novel cAMP receptor, CABP1, whose properties are consistent with the idea that this protein is involved in gene regulation. Firstly, immunological techniques using anti‐CABP1 antibodies as probes showed that this cAMP receptor can be detected on the surface of developing cells. Secondly, there is a steady migration of CABP1 to the nucleus during development. Thirdly, some genetic variants exhibiting an altered pattern of development are found to possess modified CABP1. We also showed that CABP1 co‐purifies with at least seven other polypeptides which share common epitopes with CABP1. Interestingly, four of the CABP1‐related polypeptides can be detected on the cell surface as well as in the nucleus.
Regulation of gene expression by the intracellular second messengers IP3 and diacylglycerol
Authors: Kimmel Alan R. , Eisen Michael 
Published: May 2005

AbstractIn Dictyostelium, extracellular cAMP interacts specifically with cell‐surface receptors to promote the accumulation of a variety of intracellular second messengers, such as, 3′‐5′ cyclic adenosine monophosphate (cAMP) and 1,4,5 inositol trisphosphate (IP3). We and others have shown that activation of the cell‐surface cAMP receptor can also modulate the expression of the Dictyostelium genome during development. In at least one instance, synthesis of intracellular cAMP is required for appropriate gene regulation. However, the induction of most cAMP‐dependent gene expression can occur in the absence of receptor‐mediated activation of adenylate cyclase and a consequent accumulation of intracellular cAMP. These results suggest that other intracellular second messengers produced in response to receptor activation may potentially act as signal transducers to modulate gene expression during development. In vertebrate cells, IP3 and diacylglycerol (DAG) are intracellular activators of specific protein kinases; they are produced in equimolar amounts by cleavage of phosphoinositol bisphosphate after a receptor‐mediated activation of a membrane‐bound phosphodiesterase. IP3 and, thus, by inference, diacylglycerol are synthesized in Dictyostelium as a response to cAMP interacting with its cell‐surface receptor. Using defined conditions to inhibit the accumulation of extracellular cAMP, we have examined the effects of these compounds on the accumulation of extracellular cAMP, we have examined the effects of these compounds on the expression of genes that require cAMP for their maximal expression. Our results suggest that intracellular IP3 and DAG may in part mediate the action of extracellular cAMP on the expression of the Dictyostelium genome.
A Ca2+‐dependent signal transduction system participates in coupling expression of some cAMP‐dependent prespore genes to the cell surface receptor
Authors: Blumberg Daphne D. , Comer Joann F. , Higinbotham Kathleen G. 
Published: May 2005

AbstractElevated levels of cAMP are essential for the expression of many postaggregation prespore and prestalk mRNA species and for the suppression of some growth phase mRNAs. Here we review evidence that this regulation is mediated by cAMP interacting at the cell surface receptor. These effects of cAMP on gene expression can occur under conditions where the receptor‐associated adenylate cyclase is inactivated and in concentrations that are consistent with receptor binding. A number of differences are noted in the mechanism by which cAMP regulates prespore and prestalk genes. Finally, evidence is reviewed for the role of a Ca2+‐dependent signal transduction system in coupling the expression of some of the prespore mRNAs to the cAMP receptor. This signal transduction system does not appear to be involved in the expression of the cAMP‐dependent prestalk gene.
Analysis of cis and trans elements involved in cAMP‐inducible gene expression in Dictyostelium discoideum
Authors: Hjorth Annegrethe , Datta Sumana , Khanna Navin C. , Firtel Richard A. 
Published: May 2005

AbstractExpression of the Dictyostelium discoideum pst‐cath (CP2) gene is transcriptionally regulated during multicellular development, and the gene is inducible in competent single cells following administration of exogenous cAMP. The 5′ flanking region of pst‐cath (CP2) that extends from −313 to the Cap site (+−1) has previously been shown to contain sufficient cis,‐acting regulatory elements for proper developmental and cAMP‐inducible expression of a foreign gene [Datta and Firtel, 1987, Mol Cell Biol 7:149–159]. The −283 to −201 region includes two exceptional “G‐boxes” centered at −233 and −217 respectively, and this ∼︁ 80 bp region is essential for basal as well as regulated expression of the pst‐cath (CP2) gene. Here we summarize results obtained from a detailed analysis of a series of linker‐scanner mutants and mutants that carry small internal deletions within the essential 80‐bp region. Insertion of a synthetic oligonucleotide that includes the downstream G‐box is demonstrated to rescue a low level of cAMP‐inducible expression following insertion into cassette mutants. The effect of introducing a change in the relative spacing between regulatory elements has also been investigated.We have analyzed nuclear extracts for the presence of DNA‐binding proteins that interact specifically with the pst‐cath (CP2) regulatory region and identified two such putative trans‐acting factors: (1) the AT‐factor that is observed within a few hours following the onset of starvation and that binds tightly to stretches of alternating adenine‐thymine residues (poly(dA‐dT)); and (2) the AG‐factor that is present in nuclear extracts of aggregated cells. Competition studies have demonstrated significant differences in the affinity that characterizes the binding of the two factors to G‐box‐containing sequences. The binding specificities of these DNA‐binding proteins have been analyzed using gel mobility‐shift and DNaseI footprinting assays.
Characterization of two divergently transcribed Dictyostelium gene pairs and identification of G‐rich sequence element lying between them with the characteristics of a basal promoter element
Authors: Driscoll Donna M. , Pears Catherine J. , Williams Jeffrey G. 
Published: May 2005

AbstractThe cysteine proteinase 1 (CP1) and cysteine proteinase 2 (CP2) genes of Dictyostelium discoideum encode coordinately expressed mRNA sequences that are inducible by extracellular cAMP. Both genes form part of divergently transcribed gene pairs. The gene proximal to CP1 is coordinately regulated and encodes a protein containing several potential zinc binding domains of the kind found in DNA binding proteins. The gene proximal to CP2 is a constitutively transcribed gene of unknown function. There are multiple, short, G‐rich sequence elements between both gene pairs, and deletion of the pair of elements 200 nucleotides upstream from the CP2 gene abolishes cAMP‐inducibility. A synthetic oligonucleotide, containing two copies of the G‐rich element from the CP1 gene, will reconstitute cAMP‐inducibility in the deletion mutant of the CP2 gene. This shows that the elements in the two genes are functionally homologous. Efficient induction requires at least two copies of the CP1 element, but their relative orientation is unimportant. Two copies in an inverted orientation are, however, inactive when moved upstream of their normal position and are incapable of conferring cAMP‐inducibility on a heterologous gene. These observations suggest that these sequences are either essential promoter elements, not themselves interacting with the inducer, or that their interaction with a separate class of control sequences is necessary for inducible expression.
Nuclear plasmids in the Dictyostelium slime molds
Authors: Hughes Joanne E. , Ashktorab Hassan , Welker Dennis L. 
Published: May 2005

AbstractCellular slime molds are one of only three types of eukaryotes known to contain circular nuclear plasmids. Unlike the 2‐μm circle in Saccharomyces, different strains of Dictyostelium can carry different, nonhomologous plasmids. Covalently closed, circular DNA plasmids have been identified in D. discoideum, D. mucoroides, D. giganteum, and D. purpureum. These plasmids range in size from 1.3–27 kb and in copy number from 50‐300 molecules per cell. Plasmids have been identified in approximately one‐fifth of all isolates examined. The organization of their DNA in nucleosomes establishes their presence in the nucleus. We have successfully cotransformed endogenous Dictyostelium plasmids into D. discoideum using the G418 resistance shuttle vector B10S. Transformants carrying D. discoideum plasmids are recovered at much higher frequency than those carrying plasmids from the other Dictyostelium species. We have constructed recombinant plasmids based on the D. discoideum plasmid Ddp2 and the G418 resistance gene. With these extrachromosomal vectors, transformed cells are recovered at frequencies of up to 10−4 per input cell, the vectors are stably maintained at high copy number in the absence of selection, and the vectors can be used to introduce foreign DNA sequences into D. discoideum cells.
Actin‐binding proteins are conserved from slime molds to man
Authors: Schleicher Michael , André Elisabeth , Hartmann Herbert , Noegel Angelika A. 
Published: May 2005

AbstractDNA clones encoding the actin‐binding proteins α‐actinin and severin from Dictyostelium discoideum were isolated and sequenced. Comparisons of the deduced amino acid sequences with proteins from other species showed striking similarities at distinct regions. The F‐actin cross‐linking molecule α‐actinin carries two characteristic EF‐hand structures highly homologous to the Ca2+‐binding loops of proteins from the calmodulin superfamily. An N‐terminal region that is conserved in α‐actinin from D. discoideum and vertebrates is also related to parts of the dystrophin sequence and might represent the F‐actin binding site. Severin, gelsolin, villin, and fragmin share homologous sequences that are believed to participate in the severing activity of these proteins.
Inactivation of the α‐actinin gene in Dictyostelium
Authors: Noegel Angelika A. , Witke Walter 
Published: May 2005

Abstractα‐Actinin‐negative transformants of Dictyostelium have been obtained by transforming cells with a transformation vector carrying part of the α‐actinin gene in either sense or antisense orientation. The transformants did not produce detectable α‐actinin anymore and contained an altered RNA lacking the 3′ part of the coding sequences. The deficiency in α‐actinin was due to an integration of the transformation vector into the gene, since it could be detected by Southern blot analysis in the endogenous gene.
Defective intercellular cohesion in glycosylation mutants of Dictyostelium discoideum
Authors: Boose Jeri Ann , Ziska Suzanne E. , Henderson Ellen J. 
Published: May 2005

AbstractIn order to identify the biological roles of protein‐linked oligosaccharides, we have isolated mutants by a selection for amoebae with temperature‐sensitive defects in glycan assembly and processing. Of these, 75% were also temperature sensitive for development [Boose and Henderson, 1986]. Two such mutants with distinct developmental phenotypes and glycosylation patterns are described. Mutant HT7 cannot complete aggregation at the restrictive temperature and is defective in expression of EDTA‐resistant cohesion. The biochemical defect appears to be early in glycan processing. A revertant of HT7 has recovered aggregation capability, EDTA‐resistant cohesion, and reverted almost totally to wild‐type glycosylation. Mutant HT15 aggregates at the restrictive temperature but then disperses into a cell lawn. It is less deficient in EDTA‐resistant cohesion than HT7 and has a different glycosylation profile. These results provide strong support for a role of protein N‐linked oligosaccharides in aggregation‐stage intercellular cohesion.
Signals controlling cell differentiation and pattern formation in Dictyostelium
Authors: Kay Robert R. , Berks Mary , Traynor David , Taylor Graham W. , Masento Mark S. , Morris Howard R. 
Published: May 2005

AbstractThe major inducers of cell differentiation in Dictyostelium appear to be cyclic AMP and DIF‐1. Recently we have chemically identified DIF‐1, together with the closely related DIF‐2 and ‐3. They represent a new chemical class of potent effector molecules, based on a phenyl alkanone with chloro, hydroxy, and methoxy substitution of the benzene ring. Previous work has shown that DIF‐1 can induce prestalk‐specific gene expression within 15 min, whereas it suppresses prespore differentiation. Hence, DIF‐1 can control the choice of pathway of cell differentiation in Dictyostelium and is therefore likely to be involved in establishing the prestalk/prespore pattern in the aggregate. In support of this, we show that DIF treatment of slugs results in an enlarged prestalk zone. Cyclic AMP seems less likely to have such a pathway‐specifie role, but later in development it becomes inhibitory to stalk cell differentiation. This inhibition may be important in suppressing terminal stalk cell differentiation until culmination.Spore differentiation can be induced efficiently by high levels of Br‐cyclic AMP, a permeant analogue of cyclic AMP. In this, it phenocopies certain spore‐maturation mutants, and we propose that during normal development spore differentiation is triggered by an elevation in intracellular cyclic AMP levels. How this elevation in cyclic AMP levels is brought about is not known. The experiments with Br‐cyclic AMP also provide the first direct evidence that elevated levels of intracellular cyclic AMP induce differentiation in Dictyostelium.
Lithium respecifiescyclic ‐AMP‐lnduced cell‐type specific gene expression in Dictyostelium
Authors: Van Lookeren Campagne Michiel M. , Wang Mei , Spek Wouter , Peters Dorien , Schaap Pauline 
Published: May 2005

AbstractWe investigated the effect of LiCl on pattern formation and cAMP‐regulated gene expression in Dictyostelium discoideum. In intact slugs, 5 mM LiCl induces an almost complete redifferentiation of prespore into prestalk cells. We found that LiCl acts by interfering with the transduction of extracellular cAMP to cell‐type‐specific gene expression; LiCl inhibits the induction of prespore‐specific gene expression by cAMP, while it promotes the induction of prestalk‐associated gene expression by cAMP. Our results indicate that two divergent pathways transduce the extracellular cAMP signal to, respectively, prestalk and prespore gene expression.
Geometry and spatial patterns in Polysphondylium pallidum
Authors: McNally J. G. , Cox E. C. 
Published: May 2005

AbstractThe formation of secondary sori in whorls of Polysphondylium pallidum provides an attractive model system for the study of symmetry breaking during morphogenesis. Tip‐specific antibodies that permit detection of very early stages in this patterning process are available. We have found that the patterns of tip‐specific antigen expression vary considerably depending on the size, shape, and developmental stage of the whorl. All of these patterns, however, are well explained by patterning models that rely on short‐range autocatalysis and long‐range inhibition, as exemplified by reaction‐diffusion theories. In the context of reaction‐diffusion, we discuss the possible effects of initial conditions, boundary conditions, and nonlinearities on the selection of patterns in P. pallidum whorls.
Euchromatic inversions causing mosaic gene expression in Drosophila hydei: A study of forked and Zebra
Authors: van Breugel Frans M. A. 
Published: May 2005

AbstractIn D. hydei two new mutants, In(1)f3 and IN(5)Z, show obvious mosaic gene expression. Their phenotypic expression is susceptible to the breeding temperature and to the addition of a supernumerary Y chromosome to the chromosome set. In this respect the mutants resemble standard cases of position‐effect variegation based on the action of heterochromatin. However, since neither centromeric nor sex chromosomal heterochromatin apparently are involved, the mutations point to a new type of variegation provoked by euchromatic sections. The mosaic patterns of these mutants, in particular those of In(1)f3, will be described.
Identification and expression of the gap segmentation gene hunchback in drosophila melanogaster
Authors: Bender Michael , Horikami Sandra , Cribbs David , Kaufman Thomas C. 
Published: May 2005

AbstractGenetic analysis has shown that the gap segmentation gene hunchback (hb) is a member of the genetic hierarchy involved in pattern formation in Drosophila. To identify the hb gene, we have mapped the position of hb mutant breakpoints within a chromosomal walk of the 85A region by genomic Southern blots and determined the transcription pattern of DNA from the walk. We detect a single gene within the domain defined by breakpoint mapping. We conclude that we have identified the hunchback gene because three mutations that inactivate hb physically interrupt or delete this gene. Northern analysis shows that the hb gene gives rise to at least five overlapping transcripts ranging in length from 2.6 to 3.5 kilobases. S1 nuclease and primer extension experiments demonstrate that the gene employs two promoters and three polyadenylation sites. The two hb promoters have different temporal specificities. Transcripts arising from the upstream promoter are detected from 0–12 hours of embryogenesis as well as in adult female and male RNA preparations. Transcripts arising from the downstream promoter accumulate only from 0–6 hours of embryogenesis. During the syncytial blastoderm stage, transcripts from the hb gene accumulate over a broad anterior and a narrow posterior domain. This pattern sharpens during the late blastoderm/early gastrula stage to produce an embryo with two stripes of hybridization anterior and one stripe posterior. Later, hb transcripts are detected within the ventral hypoderm in extended germ band stage embryos.
Genetic determination of sporangiophore development in Phycomyces
Authors: Gutiérrez‐Corona Félix , Cerdé‐Olmedo Enrique 
Published: May 2005

AbstractThe mycelium of the fungus Phycomyces. essentially a giant multinucleate cell, produces two kinds of asexual reproductive structures, called macrophores and microphores, and a succession of structures for sexual reproduction. Following the treatment of spores with N‐methyl‐N′ ‐nitro‐N‐nitrosoguanidine, conditional imb mutants have been isolated that form no macrophores at 26°C, but do at 14°C. At the restrictive temperature, few imb mutants (2 of 13) develop microphores, and none is able to complete the sexual cycle. This suggests that genes responsible for macrophorogenesis are involved in microphorogenesis and in sexual development as well. Light reduces macrophorogenesis and totally abolishes microphorogenesis in the wild type under the conditions of our experiments. These photomorphogenetic effects require the normal function of genes madA and madB, which are responsible for phototropism. Light inhibits microphorogenesis in the two imb mutants that form microphores at the restrictive temperature. Genetic alterations of carotenogenesis lead to an excess of microphores and a scarcity of macrophores in the dark, but they have little influence on vegetative reproduction in the light.
Epithelial differentiation in Drosophila pupae
Authors: Mitchell Hershel K. , Petersen Nancy S. 
Published: May 2005

AbstractThe construction of cell hairs on the wings in developing pupae of Drosophila provides a unique system for studies of the regulation of differentiation in the absence of cell division. Early steps in hair construction are the extrusion of cell hairs and the deposition of the external impervious layer called “cuticulin.” Some properties of six of the most abundant proteins that are present during the early stages of hair construction are described. These proteins make up about 40% of the total protein of the preparation.
Genetic analysis of chorion formation in Drosophila melanogaster: I. The effects of one somatic‐specific and seven germ‐line‐specific mutations
Authors: Galanopoulos Vasilis K. , Orr William , Szabad János , Kafatos Fotis C. 
Published: May 2005

AbstractEight X‐linked recessive female sterile mutations, derived from a hybrid dysgenic screen of Drosophila melanogaster and representing eight distinct loci, have been characterized by genetic and ultrastructural analysis. Four have abnormal respiratory appendages, three have essentially normal appendages but show moderate defects in the endochorion, and one mutant, fs(1)nela, exhibits major defects in both the endochorion and the respiratory appendages. Germ line clones of all eight mutants were generated using the dominant female sterile technique. Seven of the eight mutations are germ line specific, indicating that, although the eggshell is produced by the follicular cells, germ line functions play a significant role in its elaboration. The mutant that shows major defects, fs(1)nela, is somatic line specific, and exerts its effect in the ovary.
Genetic analysis of modifiers affecting sexual dimorphism and temperature sensitivity of bx1 in Drosophila melanogaster
Authors: Larsen Ellen 
Published: May 2005

AbstractTwo modifiers of bithorax1 phenotypic expression are described. An X‐chromosome region is associated with sexual dimorphism in bx1 penetrance. It is hypothesized that sexual dimorphism is in part due to a lack of dosage compensation of the modifier, in males. A third chromosome region that segregates with the pink peach allele is implicated in mediating temperature sensitivity. By appropriate combinations of modifiers, both sexual dimorphism and temperature sensitivity can be greatly reduced.