Fixation of [13N]N2 and transfer of fixed nitrogen in the Anthoceros-Nostoc symbiotic association

Planta ◽  
1985 ◽  
Vol 164 (3) ◽  
pp. 406-414 ◽  
Author(s):  
J. C. Meeks ◽  
C. S. Enderlin ◽  
C. M. Joseph ◽  
J. S. Chapman ◽  
M. W. L. Lollar
Keyword(s):  
Symbiotic Association ◽  
Fixed Nitrogen

Strategies used by rhizobia to lower plant ethylene levels and increase nodulation

2002 ◽  
Vol 48 (11) ◽  
pp. 947-954 ◽  
Author(s):  
Wenbo Ma ◽  
Donna M Penrose ◽  
Bernard R Glick
Keyword(s):  
Plant Root ◽  
Molecular Nitrogen ◽  
Acc Deaminase ◽  
Inhibitory Effect ◽  
Symbiotic Association ◽  
Fixed Nitrogen ◽  
Negative Factor ◽  
Negative Effect ◽  
Plant Root Elongation ◽  
Lower Plant

Agriculture depends heavily on biologically fixed nitrogen from the symbiotic association between rhizobia and plants. Molecular nitrogen is fixed by differentiated forms of rhizobia in nodules located on plant roots. The phytohormone, ethylene, acts as a negative factor in the nodulation process. Recent discoveries suggest several strategies used by rhizobia to reduce the amount of ethylene synthesized by their legume symbionts, decreasing the negative effect of ethylene on nodulation. At least one strain of rhizobia produces rhizobitoxine, an inhibitor of ethylene synthesis. Active 1-aminocyclopropane-1-carboxylate (ACC) deaminase has been detected in a number of other rhizobial strains. This enzyme catalyzes the cleavage of ACC to α-ketobutyrate and ammonia. It has been shown that the inhibitory effect of ethylene on plant root elongation can be reduced by the activity of ACC deaminase.Key words: rhizobia, nodulation, ethylene, ACC deaminase, rhizobitoxine.

Partitioning of Symbiotically Fixed Nitrogen in Soybeans and Alfalfa 1

Crop Science ◽  
1984 ◽  
Vol 24 (5) ◽  
pp. 986-990 ◽  
Author(s):  
R. A. Henson ◽  
G. H. Heichel
Keyword(s):  
Fixed Nitrogen

Researching nitrogen solubility in nitrogen-containing austenitic steels at melting and recrystallization by CALPHAD method

2019 ◽  
pp. 53-66 ◽  
Author(s):  
L. A. Smirnov ◽  
I. I. Gorbachev ◽  
V. V. Popov ◽  
A. Yu. Pasynkov ◽  
A. S. Oryshchenko ◽  
...  
Keyword(s):  
Global Minimum ◽  
Nitrogen Solubility ◽  
Thermodynamic Description ◽  
Solidus Temperature ◽  
Liquidus Line ◽  
Calphad Method ◽  
Austenitic Steels ◽  
Nitrogen Transfer ◽  
Fixed Nitrogen ◽  
System Phase

The CALPHAD method has been employed to compose thermodynamic description of the Fe–Cr–Mn–Ni–Si–C–N system. Using an algorithm based on finding a global minimum of Gibbs energy, the calculations of system phase composition were performed in the temperature range from 1750°C to hardening and in the range of compositions corresponding to 04Kh20N6G11M2AFB steel. Calculations showed that at temperatures above liquidus line, Cr and Mn increase nitrogen solubility in the melt, while Ni and Si reduce it. With an increase in the content of Cr, Mn, Ni, and Si in steel in the studied composition range, both liquidus and solidus temperature decrease. The degree of influence on these temperatures of Cr, Mn, Ni and Si within the steel grade is different and ranges from ~3 to ~14°C. Calculations taking into account the possibility of nitrogen transfer between steel and the atmosphere of air showed that the amount of fixed nitrogen in the alloy under study varies, depending on the composition of the steel and temperature, from ~0.3 to ~0.6 wt%. As the temperature decreases from liquidus to solidus, the amount of fixed nitrogen increases, with the exception of those steel compositions when ferrite and not austenite is released from the liquid phase.

scholarly journals Prevalence and Photobiology of Photosynthetic Dinoflagellate Endosymbionts in the Nudibranch Berghia stephanieae

Animals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 2200
Author(s):  
Ruben X. G. Silva ◽  
Paulo Cartaxana ◽  
Ricardo Calado
Keyword(s):  
Food Deprivation ◽  
Photosynthetic Efficiency ◽  
Rapid Decrease ◽  
Complete Loss ◽  
Symbiotic Association ◽  
Non Invasive ◽  
Sea Slugs ◽  
Non Destructive ◽  
Over Time

Berghia stephanieae is a stenophagous sea slug that preys upon glass anemones, such as Exaiptasia diaphana. Glass anemones host photosynthetic dinoflagellate endosymbionts that sea slugs ingest when consuming E. diaphana. However, the prevalence of these photosynthetic dinoflagellate endosymbionts in sea slugs appears to be short-lived, particularly if B.stephanieae is deprived of prey that host these microalgae (e.g., during bleaching events impacting glass anemones). In the present study, we investigated this scenario, along with food deprivation, and validated the use of a non-invasive and non-destructive approach employing chlorophyll fluorescence as a proxy to monitor the persistence of the association between sea slugs and endosymbiotic photosynthetic dinoflagellates acquired through the consumption of glass anemones. Berghia stephanieae deprived of a trophic source hosting photosynthetic dinoflagellate endosymbionts (e.g., through food deprivation or by feeding on bleached E. diaphana) showed a rapid decrease in minimum fluorescence (Fo) and photosynthetic efficiency (Fv/Fm) when compared to sea slugs fed with symbiotic anemones. A complete loss of endosymbionts was observed within 8 days, confirming that no true symbiotic association was established. The present work opens a new window of opportunity to rapidly monitor in vivo and over time the prevalence of associations between sea slugs and photosynthetic dinoflagellate endosymbionts, particularly during bleaching events that prevent sea slugs from incorporating new microalgae through trophic interactions.

scholarly journals Microbial niche differentiation explains nitrite oxidation in marine oxygen minimum zones

2021 ◽  
Author(s):  
Xin Sun ◽  
Claudia Frey ◽  
Emilio Garcia-Robledo ◽  
Amal Jayakumar ◽  
Bess B. Ward
Keyword(s):  
Nitrogen Loss ◽  
Niche Differentiation ◽  
Nitrite Reduction ◽  
Nitrite Oxidation ◽  
Fixed Nitrogen ◽  
Anoxic Waters ◽  
Biogeochemical Models ◽  
Nitrite Oxidizing Bacteria ◽  
Oxygen Addition ◽  
Oxygen Minimum

AbstractNitrite is a pivotal component of the marine nitrogen cycle. The fate of nitrite determines the loss or retention of fixed nitrogen, an essential nutrient for all organisms. Loss occurs via anaerobic nitrite reduction to gases during denitrification and anammox, while retention occurs via nitrite oxidation to nitrate. Nitrite oxidation is usually represented in biogeochemical models by one kinetic parameter and one oxygen threshold, below which nitrite oxidation is set to zero. Here we find that the responses of nitrite oxidation to nitrite and oxygen concentrations vary along a redox gradient in a Pacific Ocean oxygen minimum zone, indicating niche differentiation of nitrite-oxidizing assemblages. Notably, we observe the full inhibition of nitrite oxidation by oxygen addition and nitrite oxidation coupled with nitrogen loss in the absence of oxygen consumption in samples collected from anoxic waters. Nitrite-oxidizing bacteria, including novel clades with high relative abundance in anoxic depths, were also detected in the same samples. Mechanisms corresponding to niche differentiation of nitrite-oxidizing bacteria across the redox gradient are considered. Implementing these mechanisms in biogeochemical models has a significant effect on the estimated fixed nitrogen budget.

Transfer of photosynthetically fixed carbon between the prokaryotic green alga Prochloron and its ascidian host

1983 ◽  
Vol 34 (3) ◽  
pp. 431 ◽  
Author(s):  
DJ Griffiths ◽  
L Thinh
Keyword(s):  
Light Intensity ◽  
Green Alga ◽  
Host Tissue ◽  
Total Carbon ◽  
Symbiotic Association ◽  
Fixed Carbon ◽  
Low Light ◽  
Ascidian Species ◽  
Dark Fixation ◽  
Efficient Transfer

In the symbiotic association between the prokaryotic green alga Prochloron and three didemnid host species (Diplosoma similis, Lissoclinum bistratum, Trididemnum cyclops), between 6 and 51 % of the total carbon fixed during exposure for 1 h to H14CO3- in the light (150 �E m-2 s-1) becomes associated with the host tissue. Dark fixation of 14CO2 in these ascidian species and in Lissoclinum punctatum never exceeds 6% of photosynthetic fixation at saturating light intensity. The corresponding values for dark fixation of 14CO2 in isolated Prochloron cells fall within the same range. There is very little excretion of photosynthate from whole colonies of the above ascidian species nor from Didemnum molle, Lissoclinum voeltzkowi and Trididemnum miniatum (usually less than 1 % of total photosynthate at saturation light intensity), suggesting an efficient transfer mechanism from Prochloron to host. Evidence from pulse-chase experiments suggests that transfer probably involves the early products of photosynthesis. The extent of transfer of photosynthate between Prochloron and T. cyclops varies with the rate of photosynthetic 14CO2 fixation into the whole colony but there is some transfer even at low light intensities, which strongly limit photosynthesis.

Illite-smectites and the influence of burial diagenesis on the geochemical cycling of nitrogen

Clay Minerals ◽  
1998 ◽  
Vol 33 (4) ◽  
pp. 539-546 ◽  
Author(s):  
P. A. Schroeder ◽  
A. A. McLain
Keyword(s):  
Reaction Mechanisms ◽  
Ostwald Ripening ◽  
Precipitation Reaction ◽  
Oil Well ◽  
Burial Diagenesis ◽  
Fixed Nitrogen ◽  
Geochemical Cycling ◽  
Oil Generation ◽  
Fraction Increase ◽  
Changing Rate

AbstractFixed nitrogen in illite-smectites (I-S) has been measured for Miocene shales from a Gulf of Mexico oil well. Fixed N values for the <0.2 µm fraction increase with depth from 150 ppm (1000 m) to a maximum of 360 ppm (3841 m). This increase is coincident with illitization from 41% I in I-S to 75% I in I-S. Below 3841 m, fixed N values decrease to 190 ppm (4116 m) while I-S is maintained with a slight increase from 77 to 82%. The changes in fixed N with increasing illitization are consistent with the notion that illitization proceeds via both transformation and dissolution/ precipitation reaction mechanisms. The trend of decreasing fixed N in illitic I-S is compatible with surface-controlled crystal growth and Ostwald ripening mechanisms for illitization. The trend may also be linked to the timing of maximum NH] release from kerogen maturation during oil generation. The changing rate of NH+4 liberation from organic matter and multiple illitization reaction mechanisms can result in complex N geochemical cycling pathways throughout early diagenesis to metamorphism.

scholarly journals Breeding for Enhancing Legumovirus Resistance in Mungbean: Current Understanding and Future Directions

Agronomy ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 622 ◽  
Author(s):  
Chandra Mohan Singh ◽  
Poornima Singh ◽  
Aditya Pratap ◽  
Rakesh Pandey ◽  
Shalini Purwar ◽  
...  
Keyword(s):  
Mosaic Virus ◽  
Seed Quality ◽  
Soil Health ◽  
Mosaic Disease ◽  
Bipartite Begomoviruses ◽  
Yellow Mosaic Virus ◽  
Symbiotic Association ◽  
Detection Techniques ◽  
Vigna Species ◽  
Mungbean Yellow Mosaic Virus

Yellow mosaic disease (YMD) affects several types of leguminous crops, including the Vigna species, which comprises a number of commercially important pulse crops. YMD is characterized by the formation of a bright yellow mosaic pattern on the leaves; in severe forms, this pattern can also be seen on stems and pods. This disease leads to tremendous yield losses, even up to 100%, in addition to deterioration in seed quality. Symptoms of this disease are similar among affected plants; YMD is not limited to mungbean (Vigna radiata L. Wilczek) and also affects other collateral and alternate hosts. In the last decade, rapid advancements in molecular detection techniques have been made, leading to an improved understanding of YMD-causing viruses. Three distinct bipartite begomoviruses, namely, Mungbean Yellow Mosaic India Virus (MYMIV), Mungbean Yellow Mosaic Virus (MYMV), and Horsegram Yellow Mosaic Virus (HgYMV), are known to cause YMD in Vigna spp. Vigna crops serve as an excellent protein source for vegetarians worldwide; moreover, they aid in improving soil health by fixing atmospheric nitrogen through a symbiotic association with Rhizobium bacteria. The loss in the yield of these short-duration crops due to YMD, thus, needs to be checked. This review highlights the discoveries that have been made regarding various aspects of YMD affecting mungbean, including the determination of YMD-causing viruses and strategies used to develop high-yielding YMD-resistant mungbean varieties that harness the potential of related Vigna species through the use of different omics approaches.

Sign in / Sign up

Export Citation Format

Share Document