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  • 1
    Electronic Resource
    Electronic Resource
    Phylogenetic Placement of Trichonympha (1998)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 45 (1998), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Flagellated protists of the Class Hypermastigida have previously been classified on morphology alone, since no molecular sequences have been available. We have isolated DNA from 350 cells of the hypermastigote Trichonympha, manually collected from the hindgut of Zootermopsis angusticollis, and used this DNA as template for polymerase chain reaction amplification of the small-subunit ribosomal RNA gene. The DNA sequence of the amplified fragment is closely related to that of a previously-unidentified gut symbiont from the termite Reticulitermes flavipes, and phylogenetic analysis places both sequences as a sister group to the known trichomonads. in agreement with the morphological classification.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1998.tb05097.x
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Competence development by Haemophilus influenzae is regulated by the availability of nucleic acid precursors (2001)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 40 (2001), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: DNA uptake by naturally competent bacteria provides cells with both genetic information and nucleotides. In Haemophilus influenzae, competence development requires both cAMP and an unidentified signal arising under starvation conditions. To investigate this signal, competence induction was examined in media supplemented with nucleic acid precursors. The addition of physiological levels of AMP and GMP reduced competence 200-fold and prevented the normal competence-induced transcription of the essential competence genes comA and rec-2. The rich medium normally used for growth allows only limited competence. Capillary electrophoresis revealed only a subinhibitory amount of AMP and no detectable GMP, and the addition of AMP or GMP to this medium also reduced competence 20- to 100-fold. Neither a functional stringent response system nor a functional phosphoenolpyruvate:glycose phosphotransferase system (PTS) was found to be required for purine-mediated repression. Added cAMP partially restored both transcription of competence genes and competence development, suggesting that purines may reduce the response to cAMP. Potential binding sites for the PurR repressor were identified in several competence genes, suggesting that competence is part of the PUR regulon. These observations are consistent with models of competence regulation, in which depleted purine pools signal the need for nucleotides, and support the hypothesis that competence evolved primarily for nucleotide acquisition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2001.02419.x
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  • 3
    Electronic Resource
    Electronic Resource
    Regulation of competence development and sugar utilization in Haemophilus influenzae Rd by a phosphoenolpyruvate:fructose phosphotransferase system (1996)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 21 (1996), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Changes in intracellular cAMP concentration play important roles in Haemophilus influenzae, regulating both sugar utilization and competence for natural transformation. In enteric bacteria, cAMP levels are controlled by the phosphoenolpyruvate:glycose phosphotransferase system (PTS) in response to changes in availability of the preferred sugars it transports. We have demonstrated the existence of a simple PTS in H. influenzae by several methods. We have cloned the H. influenzaeptsI gene, encoding PTS Enzyme I; genome analysis locates it in a pts operon structurally homologous to those of enteric bacteria. In vitro phosphorylation assays confirmed the presence of functional PTS components. A ptsI null mutation reduced fructose uptake to 1% of the wild-type rate, and abolished fructose fermentation even when exogenous cAMP was provided. The ptsI mutation also prevented fermentation of ribose and galactose, but utilization of these cAMP-dependent sugars was restored by addition of cAMP. In wild-type cells the non-metabolizable fructose analogue xylitol prevented fermentation of these sugars, confirming that the fructose PTS regulates cAMP levels. Development of competence under standard inducing conditions was reduced 250-fold by the ptsI mutation, unless cells were provided with exogenous cAMP. Competence is thus shown to be under direct nutritional control by a fructose-specific PTS.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1996.441420.x
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  • 4
    Electronic Resource
    Electronic Resource
    Bacteria mating preferences (1991)
    [s.l.] : Nature Publishing Group
    Nature 352 (1991), S. 25-26 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] SIR — Although the parasexual processes of bacteria are very different from the sexual systems of higher eukaryotes, there are often surprising parallels. In particular, the preferential uptake of homologous transforming DNA by competent bacteria closely resembles the mating preferences ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/352025b0
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  • 5
    Electronic Resource
    Electronic Resource
    Digging up the roots of life (1996)
    [s.l.] : Nature Publishing Group
    Nature 379 (1996), S. 587-588 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] WHEN did life arise? What did it look like? These questions were once the province of theologians, but in recent years palaeontologists have been better guides. Molecular systematists have now joined the game, and the latest molecular evidence, published last month in Science1, points to a date ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/379587a0
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  • 6
    Electronic Resource
    Electronic Resource
    Male mutation rates and the cost of sex for females (1994)
    [s.l.] : Nature Publishing Group
    Nature 369 (1994), S. 145-147 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Figure 1 shows three representative selection functions9, and Fig. 2 some results of simulations using them. All partheno-genetic populations (heavy lines in Fig. 2) reach mutation/ selection equilibria at a mean fitness, Weq, of ef, where //f is the genomic mutation rate in females10'11. ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/369145a0
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    Paper (German National Licenses)
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