Fission yeast cells either remain in the mitotic cell cycle or exit to meiotic sporulation from an uncommitted G1 state dependent on the presence or absence of nitrogen source in the medium (Nurse and Bissett, 1981). We examined how heterothallic haploid cells, which cannot sporulate, behave under nitrogen-starvation for longer than 25 days at 26 degrees C. These cells were shown to enter a sta...

soil unsaturated zone is one of the important parts of hydrological cycle that has an especial role in agricultural water resources management. the objective of this research was to determine the amount of root water uptake under simultaneous water, salinity, and nitrogen stresses as prevailing conditions in arid and semi-arid regions. to do so, the experiment was conducted with four quantitati...

Over much of the ocean’s surface, productivity and growth are limited by a scarcity of bioavailable nitrogen. Sedimentary 15N records spanning the last deglaciation suggest marked shifts in the nitrogen cycle during this time, but the quantification of these changes has been hindered by the complexity of nitrogen isotope cycling. Herewepresent a database of 15N in sediments throughout the world...

The nitrogen cycle (N-cycle), principally supported by prokaryotes, involves different redox reactions mainly focused on assimilatory purposes or respiratory processes for energy conservation. As the N-cycle has important environmental implications, this biogeochemical cycle has become a major research topic during the last few years. However, although N-cycle metabolic pathways have been studi...

Intensive agricultural systems are largely responsible for the increase in global reactive nitrogen compounds, which are associated with significant environmental impacts. The nitrogen cycle in agricultural systems is complex and highly variable, which complicates characterization in environmental assessments. Appropriately representing nitrogen inputs into an ecosystem is essential to better u...

In order to accommodate the physiologically incompatible processes of photosynthesis and nitrogen fixation within the same cell, unicellular nitrogen-fixing cyanobacteria have to maintain a dynamic metabolic profile in the light as well as the dark phase of a diel cycle. The transition from the photosynthetic to the nitrogen-fixing phase is marked by the onset of various biochemical and regulat...

In order to accommodate the physiologically incompatible processes of photosynthesis and nitrogen fixation within the same cell, unicellular nitrogen-fixing cyanobacteria have to maintain a dynamic metabolic profile in the light as well as the dark phase of a diel cycle. The transition from the photosynthetic to the nitrogen-fixing phase is marked by the onset of various biochemical and regulat...

Nitrogen, although abundant in the atmosphere, is paradoxically a limited resource for multicellular organisms. In the Animalia, biological nitrogen fixation has solely been demonstrated in termites. We found that all individuals of field-collected Mediterranean fruit flies (Ceratitis capitata) harbour large diazotrophic enterobacterial populations that express dinitrogen reductase in the gut. ...

sterilized soils are commonly used for the study of xenobiotic sorption and as an abiotic control in biodegradation experiments. they are also used for the chemical study of nitrogen and carbon cycle processes and the elimination of the biological factors. in this research the effects of different soil sterilization methods such as autoclaving, fumigating and exposure to ultraviolet and microwa...

Humans continue to transform the global nitrogen cycle at a record pace, reflecting an increased combustion of fossil fuels, growing demand for nitrogen in agriculture and industry, and pervasive inefficiencies in its use. Much anthropogenic nitrogen is lost to air, water, and land to cause a cascade of environmental and human health problems. Simultaneously, food production in some parts of th...