Inhibition of carbon fixation as a function of zinc uptake in natural phytoplankton assemblages

1979 ◽  
Vol 59 (4) ◽  
pp. 937-949 ◽  
Author(s):  
Anthony G. Davies ◽  
Jillian A. Sleep
Keyword(s):  
Carbon Fixation ◽  
Natural Populations ◽  
Plant Cells ◽  
Toxic Metal ◽  
Vitamin B ◽  
Phytoplankton Assemblages ◽  
Metal Contents ◽  
Rate Limiting ◽  
Natural Phytoplankton

There is now a substantial body of evidence that the growth rates of phytoplankton in culture are more closely related to the cellular levels of the rate-limiting constituent, be it a nutrient, micronutrient or toxic metal, than to the concentrations in the supporting medium; nitrate, Caperon (1968); phosphate, Fuhs (1969); silicate, Paasche (1973); vitamin B12, Droop (1968); iron, Davies (1970); mercury, Davies (1974); cadmium, Davies (1978a). This has suggested the requirement for a technique which would allow the determination of comparable relationships for natural populations of phytoplankton - how, for instance, their carbon fixation rates depend upon the metal contents of the plant cells. Although the effects of metals upon carbon fixation in phytoplankton assemblages from several different sea areas have already been examined (Knauer & Martin, 1972; Patin et al. 1974; Zingmark & Miller, 1975; Ibragim & Patin, 1976) no data seem to have been obtained on the levels of the metals present in the phytoplankton at the time of the measurements.

Copper inhibition of carbon fixation in coastal phytoplankton assemblages

1980 ◽  
Vol 60 (4) ◽  
pp. 841-850 ◽  
Author(s):  
Anthony G. Davies ◽  
Jillian A. Sleep
Keyword(s):  
Primary Production ◽  
Metal Concentration ◽  
Water Samples ◽  
Metal Pollution ◽  
Carbon Fixation ◽  
Plant Cells ◽  
English Channel ◽  
Phytoplankton Assemblages ◽  
Effect Of Copper ◽  
Coastal Phytoplankton

The effect of copper upon carbon fixation in coastal phytoplankton assemblages has been studied in relation to both the metal concentration in the water and the levels taken up by the plant cells. The phytoplankton populations were those present in water samples collected from Station L4 in the English Channel in the late autumn of 1979. The lowest copper concentrations causing detectable inhibition of photosynthesis lay in the range 1–25 μg/1, well below the levels which have been reported to be present in some sea areas around the British Isles; metal pollution may thus be influencing primary production in these contaminated regions.

Germanic acid inhibition of carbon fixation in natural phytoplankton assemblages

1982 ◽  
Vol 27 (2) ◽  
pp. 357-361 ◽  
Author(s):  
Anthony G. Davies ◽  
Jillian A. Sleep ◽  
D. S. Harbour
Keyword(s):  
Carbon Fixation ◽  
Acid Inhibition ◽  
Phytoplankton Assemblages ◽  
Natural Phytoplankton

Freezing in Silicon at Large Undercooling

1989 ◽  
Vol 157 ◽  
Author(s):  
P.A. Stolk ◽  
A. Polman ◽  
W.C. Sinke
Keyword(s):  
Interface Temperature ◽  
Limiting Factor ◽  
Time Resolved ◽  
Large Undercooling ◽  
Explosive Crystallization ◽  
Crystallization Speed ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Rate Limiting

ABSTRACTPulsed laser irradiation is used to induce epitaxial explosive crystallization of amorphous silicon layers buried in a (100) oriented crystalline matrix. This process is mediated by a self-propagating liquid layer. Time-resolved determination of the crystallization speed combined with numerical calculation of the interface temperature shows that freezing in silicon saturates at 16 m/s for large undercooling (> 130 K). A comparison between data and different models for melting and freezing indicates that the crystallization behavior at large undercooling can be described correctly if the rate-limiting factor is assumed to be diffusion in liquid Si at the solid/liquid interface.

scholarly journals Freshwater Chlorobia Exhibit Metabolic Specialization among Cosmopolitan and Endemic Populations

mSystems ◽  
2021 ◽  
Vol 6 (3) ◽  
Author(s):  
Sarahi L. Garcia ◽  
Maliheh Mehrshad ◽  
Moritz Buck ◽  
Jackson M. Tsuji ◽  
Josh D. Neufeld ◽  
...  
Keyword(s):  
Carbon Fixation ◽  
Carbon Sources ◽  
Natural Populations ◽  
Freshwater Ecosystems ◽  
Electron Donors ◽  
Functional Ecology ◽  
Lake Ecosystems ◽  
Tropical Regions ◽  
Metabolic Versatility ◽  
Globally Distributed

ABSTRACT Photosynthetic bacteria from the class Chlorobia (formerly phylum Chlorobi) sustain carbon fixation in anoxic water columns. They harvest light at extremely low intensities and use various inorganic electron donors to fix carbon dioxide into biomass. Until now, most information on the functional ecology and local adaptations of Chlorobia members came from isolates and merely 26 sequenced genomes that may not adequately represent natural populations. To address these limitations, we analyzed global metagenomes to profile planktonic Chlorobia cells from the oxyclines of 42 freshwater bodies, spanning subarctic to tropical regions and encompassing all four seasons. We assembled and compiled over 500 genomes, including metagenome-assembled genomes (MAGs), single-amplified genomes (SAGs), and reference genomes from cultures, clustering them into 71 metagenomic operational taxonomic units (mOTUs or “species”). Of the 71 mOTUs, 57 were classified within the genus Chlorobium, and these mOTUs represented up to ∼60% of the microbial communities in the sampled anoxic waters. Several Chlorobium-associated mOTUs were globally distributed, whereas others were endemic to individual lakes. Although most clades encoded the ability to oxidize hydrogen, many lacked genes for the oxidation of specific sulfur and iron substrates. Surprisingly, one globally distributed Scandinavian clade encoded the ability to oxidize hydrogen, sulfur, and iron, suggesting that metabolic versatility facilitated such widespread colonization. Overall, these findings provide new insight into the biogeography of the Chlorobia and the metabolic traits that facilitate niche specialization within lake ecosystems. IMPORTANCE The reconstruction of genomes from metagenomes has helped explore the ecology and evolution of environmental microbiota. We applied this approach to 274 metagenomes collected from diverse freshwater habitats that spanned oxic and anoxic zones, sampling seasons, and latitudes. We demonstrate widespread and abundant distributions of planktonic Chlorobia-associated bacteria in hypolimnetic waters of stratified freshwater ecosystems and show they vary in their capacities to use different electron donors. Having photoautotrophic potential, these Chlorobia members could serve as carbon sources that support metalimnetic and hypolimnetic food webs.

scholarly journals Determination of plasma glucose enrichment in human subjects after primed, constant infusions of 13C‐glycine before and after dietary vitamin B‐6 restriction

2009 ◽  
Vol 23 (S1) ◽  
Author(s):  
Vanessa Rodrigues Silva ◽  
Yvonne Lamers ◽  
Maria Ralat ◽  
Lesa Gilbert ◽  
Christine Keeling ◽  
...  
Keyword(s):  
Plasma Glucose ◽  
Human Subjects ◽  
Dietary Vitamin ◽  
Vitamin B ◽  
Before And After
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