Biomedical subjects
Publications and source records attributed to J W Fell.
The validation of Sporidiobolus microsporus Higham, nom. nud. is based on phenotypic characterization and molecular sequence analysis of a partial region of the large sub-unit ribosomal DNA. The species is compared, based on phenotypic and molecular characteristics, with other species of Sporidiobolus and the closely related Rhodosporidium fluviale.
An investigation of the Accusport Lactate Analyser (ACC) was undertaken to assess its accuracy, linearity, reliability, and versatility. Accuracy was determined by comparing 32 blood assays on the ACC with those obtained using the Kodak Ektachem E250 (E250). Linearity was determined over the range 1.2-18.7 mmol/L. Reliability was measured at 1.7 (low) and 14.4 (high) mmol/L concentrations. Versatility involved determining the optimal sample volume, influence of haematocrit, and the effect of time delay from sampling to assay. Assays determined using the ACC confirm good agreement with the E250. The difference between the two methods compared for lactate determination does not exceed 1.1 mmol/L for concentrations up to approximately 20 mmol/L. Linearity is demonstrated by the regression equation y = 0.026 + 0.970x, r = 0.995. Reliability is expressed by the coefficient of variation of 7% (low) and 4.6% (high). The optimal sample size for accurate assay was determined to be between 20 microL and 50 microL. Mean lactate value did not vary significantly between a haematocrit of 35% and 45%. The Accusport is accurate, linear up to at least 18.7 mmol/L, has good reliability at high and low concentrations, and is able to analyse whole blood up to 15 minutes after sample application to the reagent strip.
The physiological profiles and proficiency of 32 volunteer surf life savers (LS), 15 professional lifeguards (LG), and 8 elite surf ironmen (IM) aged from 18 to 44 were compared. Measurements included anthropometry, muscular power, muscular strength-endurance, flexibility, VO2max, maximum heart rate, peak blood lactate response and proficiency in 3 rescue simulations. Both LG and IM were significantly faster than LS in all rescue simulations. IM had significantly greater VO2max (68.6 ml.kg-1.min-1) than LS (56.3) and LG (57.9). IM had significantly lower heart rates than LS after maximal swimming and running, and significantly lower blood lactate 3 minutes post swim (8.4 mmol/L) in comparison with LS (14.0) and LG (12.2). LG obtained better results than LS in 2 of the 3 muscular strength-endurance tasks. It is concluded that: LG and IM are significantly faster in aquatic rescue simulations than LS; IM have greater aerobic capacities than both other groups; the majority of Australian LS have adequate fitness and aquatic skills for surf rescue, although a small subset of LS do not. This group of poorly performing LS are not identified by current surf rescue screening procedures.
Species-specific oligonucleotide primers were designed for PCR identification of the basidiomycetous yeasts Cryptococcus neoformans, Trichosporon cutaneum and Rhodotorula mucilaginosa. The procedure uses standard PCR components including DNA from the test species and three primers: two universal external (upstream and downstream) limiting primers and a species-specific internal primer. Species identification requires the formation of a species-specific rDNA nucleotide segment that is significantly smaller (approximately 200 bp) than a non-target segment (approximately 600 bp). The procedure can be used to identify yeasts from single and mixed populations.
Classic methods for identification of yeasts rely on a variety of morphological and physiological tests that often take days to weeks to complete. We have been able to reduce the time to less than one day through the use of multiple segment-specific oligonucleotide priming of a region of the large subunit rDNA in a polymerase chain reaction. The "hot start" reaction was used with two universal external delimiting primers and one internal species-specific primer. Five specific primers were tested: a primer for a biologically similar group of Rhodotorula species, a generic (Cystofilobasidium) primer, and 3 species-specific primers (Leucosporidium scottii, Cryptococcus muscorum, and Rhodotorula mucilaginosa). In the absence of specific target DNA, the universal rDNA segment is amplified; in the presence of target DNA, the specific primer region is amplified. The technique is accurate within two base position differences when a 24 nucleotide-specific primer is used. The technique should be applicable to other marine eukaryotes.
Based on similarities in basidial morphology and nucleotide sequences of the V3 variable region in the large sub-unit ribosomal RNA, the yeast Leucosporidium lari-marini is considered phylogenetically related to the genus Cystofilobasidium. Therefore the new combination Cystofilobasidium lari-marini is proposed.
The V3 variable region of the large subunit rRNA was examined for nucleotide sequence signatures as potential taxonomic tools. Data are presented on 117 species, representing 23 genera of basidiomycetous yeasts. The results of nucleotide sequence alignments indicate that strains within species have identical base sequences and that species may differ from one another by one to more than 100 base positions. Phylogenetic analyses of the alignments indicates relationships among species, including the prediction of synonymous species and the clustering of species belonging to the Ustilaginales and Tremellales. These results suggest that species-specific nucleotide sequences can be used for the development of techniques for population analyses of a variety of marine and other microeukaryotes.
Samples of leaves of red mangrove (Rhizophora mangle) were incubated on an agar medium selective for pythiaceous oomycetes. Leaves on trees above the water did not contain oomycetes. Marine oomycetes, principally Phytophthora vesicula, had colonized leaves within 2 h of leaf submergence, probably finding them by chemotaxis. The frequency of occurrence of P. vesicula in submerged leaves reached 100% within 30 h of submergence. By 43 h most, if not all, parts of leaves were occupied, and surface treatment with a biocide indicated that leaves were occupied internally. Frequencies of P. vesicula remained near 100% through about 2 weeks of submergence and then declined to about 60% in older (>/=4 weeks) leaves. Leaves of white mangrove (Laguncularia racemosa) were also extensively occupied by P. vesicula after falling into the water column, but decaying leaves of turtlegrass (Thalassia testudinum) were not colonized by oomycetes. Ergosterol analysis indicated that the standing crop of living, non-oomycete (ergosterol-containing) fungal mass in submerged red-mangrove leaves did not rise above that which had been present in senescent leaves on the tree; decaying turtlegrass leaves had an ergosterol content that was only about 2% of the maximum concentration detected for red-mangrove leaves. These results suggest that oomycetes are the predominant mycelial eucaryotic saprotrophs of mangrove leaves that fall into the water column and that for turtlegrass leaves which live, die, and decompose under submerged conditions, mycelial eucaryotes make no substantial contribution to decomposition.
The effects of 24 to 72-hr exposure to fenthion (10(1)-10(3) ppb) were determined for a fungal community, nitrogen-fixing microbes, and representative meiofaunal and zooplankton invertebrates of a mangrove ecosystem. Also tested were the abilities of a benthic diatom and of fungi to grow in the presence of fenthion. Acute lethal, growth-inhibiting, or process-disrupting effects were not detected for exposures to less than 500 ppb fenthion. Results are compared with the findings of several other investigations of the impact of fenthion and other organophosphorus insecticides on non-target organisms.
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Metschnikowia isolates from ponds on Chatham Island, New Zealand, previously erroneously reported as M. zobellii, are described herein as M. bicuspidata var. chathamia var. n.
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