PubMed · 9370788
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G Kjaergaard, C F Hansen. 1997-07-25. [ICN: with various backgrounds].. https://pubmed.ncbi.nlm.nih.gov/9370788/
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Examination of variation in ecological communities can lead to an understanding of the forces that structure communities, the consequences of change at the ecosystem level, and the relevant scales involved. This study details spatial and seasonal variability in the composition of nitrogen-fixing and cyanobacterial (i.e., oxygenic photosynthetic) functional groups of a benthic, hypersaline microbial mat from Salt Pond, San Salvador Island, Bahamas. This system shows extreme annual variability in the salinity of the overlying water and the extent of water coverage. Analysis of molecular variance and F(ST) tests of genetic differentiation of nifH and cyanobacterial 16S rRNA gene clone libraries allowed for changes at multiple taxonomic levels (i.e., above, below, and at the species level) to inform the conclusions regarding these functional groups. Composition of the nitrogen-fixing community showed significant seasonal changes related to salinity, while cyanobacterial composition showed no consistent seasonal pattern. Both functional groups exhibited significant spatial variation, changing with depth in the mat and horizontally with distance from the shoreline. The patterns of change suggest that cyanobacterial composition was more insensitive to water stress, and consequently, cyanobacteria dominated the nitrogen-fixing community during dry months but gave way to a more diverse community of diazotrophs in wet months. This seasonal pattern may allow the mat community to respond quickly to water-freshening events after prolonged dry conditions (system recovery) and maintain ecosystem function in the face of disturbance during the wet season (system resilience).
OBJECTIVE: To assess the delivery of advanced specialized medical care using The Partnered Care Model as a means of providing affordable access to all, irrespective of ability to pay. DESIGN AND METHODS: A retrospective analysis of all persons presenting to a specialized, private, cardiac unit, The Bahamas Interventional Cardiology Center (BICC), over an 8.5-year period from March 1996 to September 2004 was conducted. The Bahamas Heart Center's Discounted Service System had been applied since inception to all patients in three groups including insured patients billed at 100% of the fee schedule of The Medical Association of the Bahamas for the procedures performed, private self-pay and government patients billed at 75% and 50% respectively. Their respective distribution and contributions to total revenue was analyzed. A series of financial models were constructed taking into consideration variables that could influence the percentages of revenues collected from each sector and the number of individuals served RESULTS: One thousand five-hundred and forty-two patients received services in BICC over the 8.5 year period (56% males and 44% females age range: 0.25 - 96 years, with mean age of 55.7 years). One thousand eight-hundred and eighty-eight patient-procedures were performed, with 51% insured generating 69% total revenue, 18% Private producing 16% Revenue, and 31% Government patients generating 15%. Financial models were created to predict revenue behaviour in various scenarios. CONCLUSION: Partnered Care is a viable alternative for Governments (Ministries of Health) of developing countries to provide costly specialized healthcare to their populations at minimal expense and capital outlay. Partnered Care reduces the otherwise overwhelming burden of healthcare cost to governments, particularly in developing countries, by sharing the burden of care between the private, user and government sectors.
A dense 1 m thick layer of phototrophic purple sulfur bacteria is present at the pycnocline (17.8 m depth) in the meromictic South Andros Black Hole cave system (Bahamas). Two purple sulfur bacteria present in samples collected from this layer have been identified as belonging to the family Chromatiaceae. One isolate (BH-1), pink coloured, is non-motile, non-gas vacuolated, 2-3 microm in diameter and surrounded by a capsule. The other isolates (BH-2 and BH-2.4), reddish-brown coloured, are small celled (4 microm x 2 microm), motile by means of a single polar flagellum. In both isolates (BH-1 and BH-2), the intracellular photosynthetic membranes are of the vesicular type and bacteriochlorophyll a and carotenoids of the normal spirilloxanthin series are present. Both isolates grow well in the presence of sulfide and carbon dioxide in the light. During photoautotrophic growth sulfur globules are stored intracellularly as intermediate oxidation products. According to the 16S rRNA gene sequence data the isolates belong to the genera Thiocapsa and Allochromatium. However, at the species level a number of inconsistencies exist between the phenotypic and phylogenetic data, highlighting taxonomic problems within these genera. These inconsistencies may have implications for microbiologists studying the ecology of anoxygenic phototrophs. For ecologists studying the functioning of an ecosystem it may not be particularly important to know whether a specific isolate belongs to one species or another. However, if one wants to study the role of different populations within a particular functional group then the species concept is important. This study demonstrates that further work is still required on the taxonomy of purple sulfur bacteria in order that microbial ecologists are able to accurately identify a population/species isolated from hitherto undescribed aquatic ecosystems.