ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Numbers of 5S and tRNA genes in macro- and micronuclei of Tetrahymena pyriformis (1976)
    Springer
    Chromosoma 54 (1976), S. 327-337 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Macronuclei of Tetrahymena pyriformis contain approximately 200 copies of the genes for 25S and 17S ribosomal RNA (rRNA) per haploid genome. Micronuclei, however, contain only a few copies of the rRNA genes per haploid complement. Since macronuclei develop from, products of meiosis, fertilization and division of micronuclei, we suggested that the multiple copies of the rRNA genes in macronuclei are generated by amplification of the small number of genes in micronuclei (Yao et al., 1974). This process provides a simple mechanism for maintaining the homogeneity of the repeated rRNA genes. To test if amplification is a general mechanism operating on all repeated genes in Tetrahymena, we have examined the numbers of 5S RNA and tRNA genes in macro- and micronuclei. 5S RNA was purified by polyacrylamide gel electrophoresis and hybridized to saturation against macro- and micronuclear DNA. Approximately 0.013–0.014% of macronuclear DNA and about 0.009% of micronuclear DNA is complementary to 5S RNA. After correcting for the differences in the DNA sequence complexities between the two nuclei, we calculate that there are 300–350 5S genes per haploid macro- or micronuclear genome. From these data we conclude that there is little or no detectable amplification of the 5S genes in macronuclei relative to micronuclei. Similar studies using tRNA indicate that these genes are also highly repeated in both nuclei; about 800 genes are present per haploid genome. Thus, amplification from a small number of genes can be excluded as the mechanism for generating the repeated copies of the 5S and tRNA genes in Tetrahymena and it is likely that another, as yet unidentified, mechanism operates to maintain the homogeneity of these genes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00292813
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    The Regulation of Dictyostelium Development by Transmembrane Signalling (1995)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 42 (1995), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . Dictyostelium discoideum has a well characterized life cycle where unicellular growth and multicellular development are separated events. Development is dependent upon signal transduction mediated by cell surface, cAMP receptor/G protein linkages. Secreted cAMP acts extracellularly as a primary signal and chemoattractant. There are 4 genes for the distinct cAMP receptor subtypes, CAR1, CAR2, CAR3 and CAR4. These subtypes are expressed with temporally and spatially specific patterns and cells carrying null mutations for each gene have distinct developmental phenotypes. These results indicate an essential role for cAMP signalling throughout Dictyostelium development to regulate such diverse pathways as cell motility, aggregation (multicellularity), cytodifferentiation, pattern formation and cell type-specific gene expression.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1995.tb01565.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Organization of the 5S RNA genes in macro- and micronuclei of Tetrahymena pyriformis (1978)
    Springer
    Chromosoma 67 (1978), S. 1-20 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The organization of the 5S genes in macro- and micronuclei of Tetrahymena pyriformis was studied using restriction endonucleases. After complete digestion of macronuclear DNA with BamH-I or Hpa I, 5S RNA hybridized to a DNA fragment of approximately 280 base pairs (bp). When macronuclear DNA was only partially digested with these enzymes, hybridization with 32P-5S RNA demonstrated an oligomeric series with a spacing of 280 bp. These results indicate that the 5S genes are tandemly repeated in macronuclei and that the repeating unit is 280 bp (or 180,000 daltons). Since 5S RNA is 120 nucleotides, we conclude that the 5S repeat units contain a 120 bp transcribed region and a 160 bp spacer region. When macronuclear DNA was digested with Eco RI, Bgl I, or Eco RI + Bgl I, 5S RNA hybridized to DNA of molecular weight 3–4×106, suggesting that these enzymes do not cleave within a 5S repeat. These 3–4×106 dalton fragments define the maximum size of an average cluster of 5S repeated units. Assuming the size of the 5S repeat to be 0.18×106 daltons, there are about 15–20 5S repeats per average tandem cluster, and since there are 350 5S-genes per haploid genome, there must be approximately 15–20 tandem arrays. Results obtained using micronuclear DNA suggest that organization of the 5S-genes is very similar in macro- and micronuclei. Macronuclear rRNA genes are extracnromosomal palindromic dimers. In contrast, 5S genes in Tetrahymena were found to be integrated within the genomes of both macro- and micronuclei and not linked to the rRNA genes. Moreover, it is unlikely that they are palindromes; rather they appear to be tandemly repeated in “head-to-tail” linkages. Thus, the organization of the 5S genes in Tetrahymena is similar to that of higher eukaryotes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00285644
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Multiple genes for cell surface cAMP receptors in Dictyostelium discoideum (1991)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 12 (1991), S. 6-13 
    Details
    ISSN: 0192-253X
    Keywords: Signal transduction ; G-proteins ; adenylyl cyclase ; gene expression ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We 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.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020120104
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Preface (1988)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 9 (1988), S. ix 
    Details
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020090402
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Structure and expression of the cAMP cell-surface receptor (1988)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 9 (1988), S. 227-235 
    Details
    ISSN: 0192-253X
    Keywords: receptors ; transmembrane signalling ; Dictyostelium ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Using 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.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020090405
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Genes encoding novel GTP-binding proteins in Dictyostelium (1988)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 9 (1988), S. 259-265 
    Details
    ISSN: 0192-253X
    Keywords: G-proteins ; gene expression ; developmental regulation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have identified a two-member gene family in the Dictyostelium genome and have isolated corresponding cDNA or genomic DNA recombinant clones. Analyses of these DNA sequences predicted encoded proteins of ∼200 amino acids with ∼90% sequence identity to each other. These Dictyostelium proteins also share amino acids identity within the GTP-binding domains in the family of G-regulatory proteins involved in cellular regulation and transmembrane signalling. Additional structural similarities are seen with members of the ras supergene family, such as ras, ral, and rho. They are similar in size (usually ∼200 amino acids), possess four conserved domains involved in GTP interaction and are believed to be anchored in the membrane by fatty acid modification of a cysteine residue near the carboxy terminus. More extensive identity is observed with YPT1 and SEC4, two other members of this family of genes that are essential in yeast. The amino-terminal half of both Dictyostelium proteins is 70% identical in amino acid sequence to the YPT1 and SEC4 yeast proteins with less identity continuing through the remainder of the proteins. In addition these proteins terminate in two cysteine residues that are thought to be required for membrane anchorage.The two genes within this Dictyostelium family are organized differently in the genome and are differentially regulated during development. One gene is colinear in sequence with its mRNA in the protein coding region, whereas the other gene encodes a spliced mRNA. The intron-containing gene is associated with a developmentally regulated (AAC)-repeat sequence. Finally, we have shown that the expression of one of the genes is induced during development with kinetics similar to that of other (AAC)n-associated genes; conversely, the expression of the second gene is repressed at a similar developmental stage.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020090408
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Regulation of gene expression by the intracellular second messengers IP3 and diacylglycerol (1988)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 9 (1988), S. 351-358 
    Details
    ISSN: 0192-253X
    Keywords: Dictyostelium ; diacylglycerol ; inositol trisphosphate ; developmetal regulation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: In 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.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020090416
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    facet.materialart.
    Unknown
    Structure of a Lipid Droplet Protein (2004)
    Cell Press
    Details
    Publication Date: 2004-07-01
    Print ISSN: 0969-2126
    Electronic ISSN: 1878-4186
    Topics: Biology , Medicine
    Published by Cell Press
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 10
    facet.materialart.
    Unknown
    Organization of the 5S RNA genes in macro- and micronuclei of Tetrahymena pyriformis (1978)
    Springer
    Details
    Publication Date: 1978-01-01
    Print ISSN: 0009-5915
    Electronic ISSN: 1432-0886
    Topics: Biology , Medicine
    Published by Springer
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...