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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Inc
    The @journal of eukaryotic microbiology 52 (2005), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. Cloning/sequencing and fragment analysis of ribosomal RNA genes (rDNA) are becoming increasingly common methods for the identification of microbial taxa. Sequences of these genes provide many additional taxonomic characters for species that otherwise have few distinctive morphological features, or that require involved microscopy or laboratory culture and testing. These same approaches are now being applied with great success in ecological studies of natural communities of microorganisms. Extensive information on the composition of natural microbial assemblages is being amassed at a rapid pace through genetic analyses of environmental samples and comparison of the resulting genetic information with well-established (and rapidly growing) public databases. We examined microbial eukaryote diversity in a natural seawater sample from the coastal western North Atlantic Ocean using two molecular biological approaches: the cloning and sequencing of rRNA genes and by fragment analysis of these genes using the terminal restriction fragment length polymorphism (T-RFLP) method. A simple experiment was carried out to examine changes in the overall eukaryote (largely protistan) diversity and species composition (phylotype diversity) of a natural microbial assemblage when a seawater sample is placed in a container and incubated at ambient light and temperature for 72 h. Containment of the natural seawater sample resulted in relatively minor changes in the overall eukaryote diversity (species richness) obtained by either molecular method at three time points (time-zero, time-24 h, time-72 h). However, substantial changes in the dominance of particular eukaryote phylotypes took place between the three sampling times. Only 18% of the total number of phylotypes observed in the study were observed at all three time points, while 65% (108 of 165) phylotypes were observed only at a single time point (54 unique phylotypes initially, 37 more unique phylotypes at 24 h, and 17 more at 72 h). The results of this study indicate that a high diversity of protistan taxa existed in the original seawater sample at very low abundance, and thus were not observed in the initial characterization of community structure. Containment resulted in significant shifts in the dominance of these taxa, enabling the presence of previously unobserved phylotypes to be documented after 24 or 72 h of incubation.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Inc
    The @journal of eukaryotic microbiology 52 (2005), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Traditional microscope-based studies of protistan assemblages in the Ross Sea, Antarctica have contributed significantly to our understanding of the microbial biogeography and food web structure in this extreme cold-water environment. However, these investigations have neither been able to characterize the genetic diversity of the communities, nor have they necessarily determined the abundances or trophic contribution of the dominant organisms. Resolution of the latter issue is hindered by the fact that physiological studies are often conducted on opportunistic species that respond to enrichment culture rather than species truly representative of intact communities. Therefore, we sought to determine the genetic diversity of microbial eukaryotes in ice, water and slush samples from the Ross Sea, and establish both morphologic and physiologic links between enrichment cultures and the genetic data. Denaturing gradient gel electrophoresis and ribosomal clone library analyses indicate that the protistan communities are very diverse, but those present in similar habitats are more alike than those in different habitats at the same site. We have been able to identify several protists from our enrichment cultures as being genetically represented in the original samples. General studies of their physiology have been initiated and methods for determining their abundances are being developed.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Inc
    The @journal of eukaryotic microbiology 52 (2005), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Ice, slush, sediment and water samples were collected from the Ross Sea, Antarctica and enriched with a variety of inorganic and organic nutrients. All cultures were maintained at an ambient temperature of 1°C, and amoebae were observed to occur in the slush, sediment and water enrichments. Amoebae were isolated into clonal or monocultures, and their characterization was accomplished using a combination of molecular and morphological methods. Full-length 18S ribosomal DNA sequence data indicated that seven of the isolates represented four different amoebae of the Vexilliferidae and Vannellidae families. Acquisition of 18S ribosomal sequences from the parasomes of two amoebae further confirmed their identification as Neoparamoeba species. Light microscopy, fluorescence microscopy and TEM observations were accomplished and further support the molecular data. To determine whether these amoebae represented psychrophilic strains, their temperature tolerances were tested. Cultures were inoculated at 1°C and the temperature was raised 1°C/day (to a total of 5°), and then held at that temperature for 6 days. This pattern was repeated in 5°-increments, up to 20°C. The cultures were observed frequently for death and possible cyst formation. Three (2 types of Vannellids) out of seven amoeba cultures survived up to 20°C. Whereas, the two different Vexilliferids died at a range of temperatures between 10°C and 20°C. These data indicate that amoebae found in the Antarctic are varied in their physiological adaptation for growth at cold temperatures.
    Type of Medium: Electronic Resource
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  • 4
    Publication Date: 2022-05-25
    Description: Author Posting. © National Shellfisheries Association, 2005. This article is posted here by permission of National Shellfisheries Association for personal use, not for redistribution. The definitive version was published in Journal of Shellfish Research 24 (2005): 719-731, doi:10.2983/0730-8000(2005)24[719:NSRRGC]2.0.CO;2.
    Description: Western Long Island Sound (LIS) lobsters collected by trawl surveys, lobstermen and coastal residents during 2000 to 2002 were identified histologically as infected with a parasome-containing amoeba. Primers to conserved SSU rRNA sequences of parasome-containing amoebae and their nonparasome-containing relatives were used to amplify overlapping SSU rRNA fragments of the presumptive parasite from gill, antenna, antennal gland and ventral nerve cord of infected lobsters. The consensus sequence constructed from these fragments had 98% or greater nucleotide sequence identity with SSU rRNA gene sequences of strains of Neoparamoeba pemaquidensis and associated with high confidence in distance- and parsimony-based phylogenetic analyses with strains of Neoparamoeba pemaquidensis and not members of the family Paramoebidae, e.g., Paramoeba eilhardi. Primers designed to SSU rRNA sequences of the lobster amoeba and other paramoebid/vexilliferid amoebae were used in a nested polymerase chain reaction (PCR) protocol to test DNA extracted from formalin-fixed paraffin-embedded tissues of lobsters collected during the 1999 die-off, when this amoeba initially was identified by light and electron microscopy and reported to be a paramoeba of the genera Paramoeba or Neoparamoeba (Mullen et al. 2004). All sequences amplified from 1999 lobsters, with the exception of one, had 98% to 99% identity to each other, and the 1999 PCR product consensus had 98% identity to Neoparamoeba pemaquidensis strains CCAP 1560/4 (AF371969.1) and 1560/5 (AF371970.1). Molecular characterization of the amoeba from western LIS lobsters by direct amplification circumvents a collective inability to culture the organism in vitro, provides insight into the molecular epidemiology of neoparamoebiasis in American lobster, and allows for PCR-based detection of infected lobsters for future research and diagnostics.
    Description: Funding for this work was provided by the Connecticut Department of Environmental Protection under Long Island Sound Research Fund Grant No. CWF 333-R to S. Frasca; and by the Connecticut Sea Grant College Program, Grants No. LR/LR-4 to R. Gast and No. LR/LR-5 to P. Gillevet and C. O’Kelly, through the US Department of Commerce, National Oceanic and Atmospheric Administration (NOAA), Award NA16RG1364.
    Keywords: Homarus americanus ; Lobster ; Molecular phylogeny ; Neoparamoeba pemaquidensis ; Paramoebiasis ; PCR ; Small-subunit rRNA
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
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