A new nitrogen-fixing Clostridium species from a high Arctic ecosystem

1979 ◽  
Vol 25 (8) ◽  
pp. 947-948 ◽  
Author(s):  
D. C. Jordan ◽  
Patricia J. McNicol
Keyword(s):  
Nitrogen Fixation ◽  
Nitrogenase Activity ◽  
High Arctic ◽  
Undescribed Species ◽  
Nitrogen Fixing ◽  
Canadian High Arctic ◽  
Clostridium Species ◽  
Gram Negative ◽  
Arctic Ecosystem ◽  
Devon Island

A hitherto undescribed species of yellow-pigmented, Gram-negative Clostridium sp., possessing nitrogenase activity, has been isolated from a number of sampling sites on the Truelove Lowland of Devon Island in the Canadian high Arctic. This bacterium, tentatively designated Clostridium arcticum sp. nov., accounted for 19% of all isolates recovered which were capable of anaerobic nitrogen fixation.

Taxonomic and ecologic observations of zoosporic fungi in soils of a high-arctic ecosystem

1976 ◽  
Vol 54 (5-6) ◽  
pp. 533-538 ◽  
Author(s):  
Tom Booth ◽  
Paul Barrett
Keyword(s):  
Species Diversity ◽  
Species Composition ◽  
Soil Acidity ◽  
High Arctic ◽  
Arctic Ecosystem ◽  
Devon Island ◽  
Zoosporic Fungi

Phylctochytrium arcticum Barr and Rhizophlyctis harderi Uebelmesser are reported as additional taxa in soils of Truelove Lowland (Devon Island, N.W.T.) and Nowakowskiella spp., Olpidium pendulum Zopf, Pythium irregularae Buisman. Pythium spp., Phlyctochytrium arcticum, and Rhizophydium sphaerotheca Zopf are readily detectable as active organisms in Lowland microhabitats. Species diversity is greatest in mesic and warm soils and species composition of water-logged soils is different than dry soils. Soil acidity effects on distribution are discussed and autecological considerations of Nowakowskiella elegans and R. sphaerotheca with respect to pH, percentage N, C, and P, milliequivalents Ca2+ and Mg2+, moisture, and temperature are presented.

Nitrogen fixation

1976 ◽  
Vol 274 (934) ◽  
pp. 341-358 ◽  
Keyword(s):  
Nitrogen Fixation ◽  
Metabolic Regulation ◽  
Higher Plants ◽  
Focal Point ◽  
Nitrogenase Activity ◽  
Nitrogen Fixing ◽  
Blue Green Algae ◽  
International Biological Programme ◽  
The 1960S ◽  
Biological Programme

The International Biological Programme served as a focal point for studies on biological nitrogen fixation during the 1960s. The introduction of the acetylene reduction technique for measuring nitrogenase activity in the field led to estimates becoming available of the contribution of lichens, blue-green algae, nodulated non-legumes and bacterial-grass associations, as well as of legumes. Other studies carried out on the physiology and biochemistry of the process led to the eventual purification and characterization of the nitrogenase enzyme. These studies, collectively, provided the springboard for current work, so essential in view of the present energy crisis, on how to increase the use and efficiency of nitrogen-fixing plants, on the metabolic regulation of the nitrogenase enzyme and on the genetics of the nitrogen-fixing process, both in higher plants and in free-living micro-organisms.

Nitrogen fixation and photosynthesis in high arctic forms of Nostoc commune

1994 ◽  
Vol 72 (7) ◽  
pp. 940-945 ◽  
Author(s):  
R. Lennihan ◽  
D. M. Chapin ◽  
L. G. Dickson
Keyword(s):  
Nitrogen Fixation ◽  
Acetylene Reduction ◽  
Terrestrial Ecosystems ◽  
Growing Season ◽  
High Arctic ◽  
Colony Morphology ◽  
Nostoc Commune ◽  
Devon Island ◽  
Low Levels ◽  
Temperature Optima

Nostoc commune, a colonial cyanobacterium, has been suggested as an important contributor of nitrogen to terrestrial ecosystems in the Canadian High Arctic, yet little is known about the ecophysiology of this organism in arctic environments. This study focused on the physiological performance of macroscopic colonies of N. commune found on Devon Island, N.W.T. The objectives were to examine the influence of temperature, colony morphology, and seasonal phenology on nitrogen fixation rates and the effects of light and temperature on photosynthesis. Maximum rates of acetylene reduction in N. commune (2119 nmol C2H4∙g−1∙h−1) were higher than those previously recorded for arctic N. commune but lower than values reported for temperate poulations. Depending on the time of the growing season, the temperature optimum for acetylene reduction varied from 15 °C to greater than 20 °C. Photosynthetic temperature optima did not occur below 20–25 °C (the highest temperatures measured). Light saturation of photosynthesis was reached at low levels of irradiance (100–150 μmol∙m−2∙s−1 PPFD). Acetylene reduction rates varied strongly with colony morphology. Thin, fragile, flattened colonies had higher rates than thicker, more resilient, flattened colonies or spherical colonies. Cold post-thaw temperatures appeared to delay the recovery of maximum nitrogen fixation rates for 2–3 weeks following the onset of the growing season. Compared with two other species of cyanobacteria present on Truelove Lowland (Gloeocapsa alpina and Gleotrichia sp.), N. commune had higher rates of nitrogen fixation. Key words: Nostoc commune, cyanobacteria, High Arctic, nitrogen fixation, photosynthesis.

scholarly journals A new hesperornithiform (Aves) specimen from the Late Cretaceous Canadian High Arctic with comments on high-latitude hesperornithiform diet

2016 ◽  
Vol 53 (12) ◽  
pp. 1476-1483 ◽  
Author(s):  
Laura E. Wilson ◽  
Karen Chin ◽  
Stephen L. Cumbaa
Keyword(s):  
Late Cretaceous ◽  
High Latitude ◽  
Upper Cretaceous ◽  
Current Knowledge ◽  
High Arctic ◽  
Time Of Death ◽  
Canadian High Arctic ◽  
Size And Shape ◽  
Devon Island ◽  
Paleoecological Reconstructions

Here we describe a new hesperornithiform specimen from the Upper Cretaceous Kanguk Formation of Devon Island, Nunavut, Canada. This specimen (NUVF 286) is referred to cf. Hesperornis sp. based on size and shape of femora and teeth preserved with other skeletal elements. Previous osteohistologic analyses indicate a subadult ontogenetic stage at the time of death. This new cf. Hesperornis specimen includes the first teeth associated with a high-latitude hesperornithiform, allowing for comments on the trophic behavior of these birds. Paleoecological reconstructions based on current knowledge of polar assemblages and comparisons to modern birds suggest that high-latitude hesperornithiform birds may have had more varied diets than previously assumed.

Characterization of a nitrogen-fixing bacterial strain from the roots of Digitaria sanguinalis

1976 ◽  
Vol 22 (2) ◽  
pp. 254-260 ◽  
Author(s):  
Lynn E. Barber ◽  
Harold J. Evans
Keyword(s):  
Nitrogen Fixation ◽  
Bacterial Strain ◽  
Optimal Growth ◽  
Root Systems ◽  
Mixed Cultures ◽  
Nitrogen Fixing ◽  
Digitaria Sanguinalis ◽  
Gram Negative ◽  
Root Sample

Rates of nitrogen fixation of 3 to 10 g of N2 fixed per hectare per day were associated with root systems of Digitaria sanguinalis. A Gram-negative motile aerobic bacterial strain that was capable of N2 fixation was isolated from a washed root sample of one of these plants. Optimal growth and N2 fixation occurred at a pH of about 6.5, a temperature of 30–37 °C, and at a pO2 of about 0.01 atm. Increased rates of N2 fixation resulted when this strain was grown in mixed cultures with aerobic or facultative bacteria. Observations of cellular and cultural morphology and results of biochemical and physiological studies indicate that the isolate may be related to the Azotobacteraceae but that it is not identical with any of the members of this family. The importance of N2 fixation by this isolate in nature is unknown.

scholarly journals Geological overview and cratering model for the Haughton impact structure, Devon Island, Canadian High Arctic

2005 ◽  
Vol 40 (12) ◽  
pp. 1759-1776 ◽  
Author(s):  
Gordon R. Osinski ◽  
Pascal Lee ◽  
John G. Spray ◽  
John Parnell ◽  
Darlene S. S. Lim ◽  
...  
Keyword(s):  
High Arctic ◽  
Impact Structure ◽  
Canadian High Arctic ◽  
Devon Island
Sign in / Sign up

Export Citation Format

Share Document