Feasibility of /sup 55/Fe autoradiography as performed on N/sub 2/-fixing Anabaena spp. populations and associated bacteria
/sup 55/Fe emits low-energy X rays and Auger electrons by electron capture decay. Auger electrons are useful for autoradiographic examination of /sup 55/Fe incorporation among microbial communities. Attainable resolution, in terms of silver grain deposition, is excellent and comparable to /sup 3/H. Two known Fe-demanding processes, photosynthetic CO/sub 2/ fixation and N/sub 2/ fixation, were examined by autoradiography of Anabaena populations. During photosynthetically active (illuminated) N/sub 2/-fixing periods, biological incorporation of /sup 55/FeCl/sub 3/ by vegetative cells and heterocysts was evident. When N/sub 2/ fixation was suppressed by NH/sub 4//sup +/ additions, heterocysts revaled no incorporation of /sup 55/Fe. Conversely, when N/sub 2/-fixing Anabaena filaments were placed in darkness, /sup 55/Fe incorporation decreased in vegetative cells, whereas heterocysts showed sustained rates of /sup 55/Fe incorporation. Bacteria actively incorporated /sup 55/Fe under both light and dark conditions. The chelated (by Na/sub 2/-ethylenediaminetetraacetate) form of /sup 55/FeCl/sub 3/ was more readily incorporated than the nonchelated form. Furthermore, abiotic adsorption of /sup 55/Fe to filters and nonliving particles proved lower when chelated /sup 55/Fe was used in experiments. /sup 55/Fe autoradiography is useful for observing the fate and cellular distribution of various forms of Fe among aquatic microbial communities.
- Research Organization:
- Univ. of North Carolina, Morehead, NC
- OSTI ID:
- 5503811
- Journal Information:
- Appl. Environ. Microbiol.; (United States), Vol. 43:1
- Country of Publication:
- United States
- Language:
- English
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ALGAE
AUTORADIOGRAPHY
BACTERIA
IRON 55
TRACER TECHNIQUES
AQUATIC ECOSYSTEMS
AUGER ELECTRON SPECTROSCOPY
CARBON DIOXIDE
COMPARATIVE EVALUATIONS
FEASIBILITY STUDIES
IRON CHLORIDES
NITROGEN FIXATION
TRITIUM COMPOUNDS
X RADIATION
BETA DECAY RADIOISOTOPES
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
CHLORIDES
CHLORINE COMPOUNDS
ECOSYSTEMS
ELECTROMAGNETIC RADIATION
ELECTRON CAPTURE RADIOISOTOPES
ELECTRON SPECTROSCOPY
EVEN-ODD NUCLEI
HALIDES
HALOGEN COMPOUNDS
INTERMEDIATE MASS NUCLEI
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IRON COMPOUNDS
IRON ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
LABELLED COMPOUNDS
MICROORGANISMS
NUCLEI
OXIDES
OXYGEN COMPOUNDS
PLANTS
RADIATIONS
RADIOISOTOPES
SPECTROSCOPY
TRANSITION ELEMENT COMPOUNDS
YEARS LIVING RADIOISOTOPES
550701* - Microbiology- Tracer Techniques
550201 - Biochemistry- Tracer Techniques