ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

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
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The pathogenic fungus Candida albicans commonly causes mucosal surface infections. In immunocompromised patients, C. albicans may penetrate into deeper tissue, enter the bloodstream and disseminate within the host causing life-threatening systemic infections. In order to elucidate how C. albicans responds to the challenge of a blood environment, we analysed the transcription profile of C. albicans cells exposed to human blood using genomic arrays and a cDNA subtraction protocol. By combining data obtained with these two methods, we were able to identify unique sets of different fungal genes specifically expressed at different stages of this model that mimics bloodstream infections. By removing host cells and incubation in plasma, we were also able to identify several genes in which the expression level was significantly influenced by the presence of these cells. Differentially expressed genes included those that are involved in the general stress response, antioxidative response, glyoxylate cycle as well as putative virulence attributes. These data point to possible mechanisms by which C. albicans ensures survival in the hostile environment of the blood and how the fungus may escape the bloodstream as an essential step in its systemic dissemination.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: In filamentous fungi, glycerol biosynthesis has been proposed to play an important role during conidiospore germination and in response to a hyperosmotic shock, but little is known about the genes involved. Here, we report on the characterization of the major Aspergillus nidulans glycerol 3-phosphate dehydrogenase (G3PDH)-encoding gene, gfdA. G3PDH is responsible for the conversion of dihydroxyacetone phosphate (DHAP) into glycerol 3-phosphate (G3P), which is subsequently converted into glycerol by an as yet uncharacterized phosphatase. Inactivation of gfdA does not abolish glycerol biosynthesis, showing that the other pathway from DHAP, via dihydroxyacetone (DHA), to glycerol is also functional in A. nidulans. The gfdA null mutant displays reduced G3P levels and an osmoremediable growth defect on various carbon sources except glycerol. This growth defect is associated with an abnormal hyphal morphology that is reminiscent of a cell wall defect. Furthermore, the growth defect at low osmolarity is enhanced in the presence of the chitin-interacting agent calcofluor and the membrane-destabilizing agent sodium dodecyl sulphate (SDS). As inactivation of gfdA has no impact on phospholipid biosynthesis or glycolytic intermediates levels, as might be expected from reduced G3P levels, a previously unsuspected link between G3P and cell wall integrity is proposed to occur in filamentous fungi.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The pathogenic fungus, Candida albicans contains homologues of the transcriptional repressors ScTup1, ScMig1 and ScNrg1 found in budding yeast. In Saccharomyces cerevisiae, ScMig1 targets the ScTup1/ScSsn6 complex to the promoters of glucose repressed genes to repress their transcription. ScNrg1 is thought to act in a similar manner at other promoters. We have examined the roles of their homologues in C. albicans by transcript profiling with an array containing 2002 genes, representing about one quarter of the predicted number of open reading frames (ORFs) in C. albicans. The data revealed that CaNrg1 and CaTup1 regulate a different set of C. albicans genes from CaMig1 and CaTup1. This is consistent with the idea that CaMig1 and CaNrg1 target the CaTup1 repressor to specific subsets of C. albicans genes. However, CaMig1 and CaNrg1 repress other C. albicans genes in a CaTup1-independent fashion. The targets of CaMig1 and CaNrg1 repression, and phenotypic analyses of nrg1/nrg1 and mig1/mig1 mutants, indicate that these factors play differential roles in the regulation of metabolism, cellular morphogenesis and stress responses. Hence, the data provide important information both about the modes of action of these transcriptional regulators and their cellular roles. The transcript profiling data are available at /transcriptdata/.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The role of cAMP signalling during germination of asexual spores (conidia) of the filamentous fungus Aspergillus nidulans was investigated. A. nidulans strains defective for adenylate cyclase (CyaA) or for the functionally overlapping cAMP-dependent protein kinase (PkaA) and newly characterized SchA protein kinase, homologous to Saccharomyces cerevisiae Sch9, show altered trehalose mobilization and kinetics of germ tube outgrowth, in addition to other defects in colony formation. cAMP-dependent trehalose breakdown is triggered by the addition of a carbon source independently of further catabolism, suggesting that cAMP signalling controls early events of conidial germination in response to carbon source sensing. Additional results suggest that cAMP has targets other than PkaA and SchA and that PkaA retains activity in the absence of cAMP. Conversely, PkaA regulates cAMP levels in A. nidulans because these are elevated by ≈ 250-fold in a strain that lacks PkaA. Furthermore, analysis of mutant strains impaired in both adenylate cyclase and RasA GTPase previously implicated in the control of A. nidulans spore germination suggested that RasA and cAMP signalling proceed independently during germination in A. nidulans.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 24 (1997), S. 0 
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Aspergillus nidulans conidiospores contain high levels of the non-reducing disaccharide trehalose. We show that upon induction of conidiospore germination, the trehalose pool is rapidly degraded and a glycerol pool is transiently accumulated. A trehalase with an acidic pH optimum was purified from conidiospores. Characterization of the treA gene encoding this trehalase shows that it is homologous to Saccharomyces cerevisiae vacuolar acid trehalase, the product of the ATH1 gene, and to two related proteins of unknown function identified in Mycobacterium tuberculosis and Mycobacterium leprae. A. nidulans mutants that lack acid trehalase activity were constructed by gene replacement at the treA locus. Analysis of these mutants suggests that the treA gene product is localized in the conidiospore wall, is required for growth on trehalose as a carbon source, and is not involved in the mobilization of the intracellular pool of trehalose. Therefore, it is proposed that a cytoplasmic regulatory trehalase is controlling this latter process.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: A cAMP-activatable Ca2+-dependent neutral trehalase was identified in germinating conidia of Aspergillus nidulans and Neurospora crassa. Using a PCR approach, A. nidulans and N. crassa genes encoding homologues of the neutral trehalases found in several yeasts were cloned and sequenced. Disruption of the AntreB gene encoding A. nidulans neutral trehalase revealed that it is responsible for intracellular trehalose mobilization at the onset of conidial germination, and that this phenomenon is partially involved in the transient accumulation of glycerol in the germinating conidia. Although trehalose mobilization is not essential for the completion of spore germination and filamentous growth in A. nidulans, it is required to achieve wild-type germination rates under carbon limitation, suggesting that intracellular trehalose can partially contribute the energy requirements of spore germination. Furthermore, it was shown that trehalose accumulation in A. nidulans can protect germinating conidia against an otherwise lethal heat shock. Because transcription of the treB genes is not increased after a heat shock but induced upon heat shock recovery, it is proposed that, in filamentous fungi, mobilization of trehalose during the return to appropriate growth is promoted by transcriptional and post-translational regulatory mechanisms, in particular cAMP-dependent protein kinase-mediated phosphorylation.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: We have characterized the Aspergillus nidulans gldB gene encoding a NADP+-dependent glycerol dehydrogenase. A basal expression level was observed for gldB, which increased significantly under conditions of hyper-osmotic shock (1 M NaCl). Growth of strains in which gldB was disrupted was severely reduced on plates containing 1% glucose and 1 M NaCl, but these strains were able to grow on plates containing 1 M NaCl and 1% glycerol, arabitol, mannitol or erythritol. Uptake of these polyols compensated for the inability of the gldB disruptants to produce glycerol. Presence of 1% glucose in these plates prevented growth restoration by all the polyols tested with the exemption of glycerol, indicating that uptake of mannitol, arabitol and erythritol is subject to glucose repression, whereas uptake of glycerol is significantly less or not repressed. No intracellular glycerol dehydrogenase activity could be detected in the gldB disruption strains. Intracellular glycerol levels in these strains were strongly decreased compared to wild type, whereas intracellular mannitol, erythritol and arabitol levels were increased. Conidia of the gldB disruption strain did not accumulate glycerol upon germination in glucose media with or without 1 M NaCl and germ tube emergence was significantly delayed in this strain in the presence of 1 M NaCl in comparison to the wild type. These data indicate that gldB is essential for osmotolerance in A. nidulans and that the pathways for glycerol biosynthesis under osmotic stress differ between yeast and filamentous fungi.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Biofilm is the predominant type of microbial development in natural environments, and potentially represents a major form of resistance or source of recurrence during host infection. Although a large number of studies have focussed on the genetics of bacterial biofilm formation, very little is known about the genes involved in this type of growth in fungi. A genetic screen for Candida glabrata Biofilm mutants was performed using a 96-well plate model of biofilm formation. Study of the isolated mutant strains allowed the identification of four genes involved in biofilm formation (RIF1, SIR4, EPA6 and YAK1). Epa6p is a newly identified adhesin required for biofilm formation in this pathogenic yeast. EPA6 and its close paralogue EPA7 are located in subtelomeric regions and their transcription is regulated by Sir4p and Rif1p, two proteins involved in subtelomeric silencing. Biofilm growth conditions induce the transcription of EPA6 and EPA7: this is dependent on the presence of an intact subtelomeric silencing machinery and is independent of the Mpk1p signalling pathway. Finally, the kinase Yak1p is required for expression of both adhesin genes and acts through a subtelomeric silencing machinery-dependent pathway.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The aspergilli comprise a diverse group of filamentous fungi spanning over 200 million years of evolution. Here we report the genome sequence of the model organism Aspergillus nidulans, and a comparative study with Aspergillus fumigatus, a serious human pathogen, and Aspergillus oryzae, used in the ...
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    ISSN: 1432-0983
    Keywords: Key wordsAspergillus fumigatus ; DNA-mediated transformation ; Orotidine 5′-monophosphate decarboxylase ; Electroporation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A homologous transformation system for the opportunistic fungal pathogen Aspergillus fumigatus was developed. It is based on the A. fumigatus pyrG gene, encoding orotidine 5′-monophosphate decarboxylase, which was cloned and sequenced. Transformation of both Aspergillus (Emericella) nidulans and A. fumigatus pyrG mutant strains by the use of protoplasts or electroporation established the functionality of the cloned gene. DNA sequencing of the A. fumigatus pyrG1 mutant allele revealed that it encodes a truncated, non-functional, PyrG protein. Transformation of an A. fumigatus pyrG1 mutant with a plasmid carrying the novel pyrG2 allele constructed by in vitro mutagenesis yielded prototrophic transformants following recombination between both mutation sites. Analysis of transformants carrying the entire plasmid showed that up to 45% of integration had occurred at the pyrG locus. This provides a tool to target defined genetic constructs at a specific locus in the A. fumigatus genome in order to study gene regulation and function.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...