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  • 1
    Electronic Resource
    Electronic Resource
    An alternative approach for the molecular characterization of uncultivable protists retaining morphological information (2005)
    Oxford, UK : Blackwell Science Inc
    The @journal of eukaryotic microbiology 52 (2005), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Recent culture-independent studies based on small-subunit ribosomal RNA (SSU rRNA) gene analysis revealed the existence of completely new clades of protists. The main problems with this approach are to correlate sequences from environmental rRNA genes with the organisms they belong to and then to detect the ecological role of these organisms in the environment. In order to overcome such problems we chose an alternative approach allowing us both a molecular characterization of uncultivable organisms with a low relative abundance in environmental samples, and a morphological analysis, even if restricted. The experimental protocol consists of two steps: an initial observation and photo-taking of the single cell under the DIC (Differential Interferential Contrast) microscope and then PCR amplification and direct sequencing of the 18S rRNA gene of the same cell. The advantages of this method are the possibility to: (1) establish a precise link between morphology and gene sequence; (2) detect the possible occurrence of highly similar species within the studied population; (3) avoid the insertion of Taq-polymerase errors in the gene sequence; and (4) detect possible polymorphisms in the gene under examination. Such an approach was used to sequence the 18S rRNA gene of organisms belonging to the class Karyorelictea that comprises several uncultivable ciliates with limited distinctive features. Gene sequences analysis revealed an unexpected genetic variability in trachelocercids and, in particular, the existence of polymorphisms in the SSU rRNA gene of a group of them. Such specimens show a similar morphology and, as a result of phylogenetic analysis, they form a constant clade.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.2005.05202003_6_2.x
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  • 2
    Electronic Resource
    Electronic Resource
    The interstitial ciliated protozoa of a Mediterranean microcommunity (1992)
    Springer
    Hydrobiologia 230 (1992), S. 79-92 
    Details
    ISSN: 1573-5117
    Keywords: ciliated protozoa ; Mediterranean sea ; interstitial environment ; diversity ; interspecific interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The main features of an interstitial ciliate community, living in the coastal sand of the Mediterranean sea, were analyzed during a one-year survey, carried out on 113 samples. The community was composed of 56 species, 31 of which belong to 8 ‘resident’ genera. Total density varied from 0 to 410 individuals cm−3 and followed a Spring-Summer and an Autumn-Winter trend, not related to temperature or to any single abiotic variable (interstitial dissolved O2, grain sand size, salinity), although the density of some taxa was related to one abiotic factor. During Spring, diversity increased by a synchronous bloom involving the whole community. Some taxa, such as the predator Lacrymaria and its prey Frontonia, were significantly associated. The finding of the simultaneous bloom of congeneric species, like that of the genus Remanella suggests that they respond to the same environmental factors, and avoid interspecific competition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00006128
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    Paper (German National Licenses)
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