Effects of L-methionine-DL-sulphoximine on the assimilation of newly fixed NH3, acetylene reduction and heterocyst production in Anabaena cylindrica

Stewart, W. D. P.; Rowell, P.

doi:10.1016/s0006-291x(75)80463-3

Cited by 259 publications

(118 citation statements)

References 13 publications

Supporting

Mentioning

110

Contrasting

Order By: Relevance

“…Although one must be cautious about the interpretation of this finding because the Nostoc colonies were not axenic, three points may be noted. First, the results are rather similar to what is found when the analogue L-methionine-DL-sulphoximine (MSO) is added to N2-fixing cultures of the free-living Anabaena cylindrica (Stewart and Rowell, 1975). Second, although our results do not necessarily imply that the effector responsible is an inhibitor of the MSO type, it is clearly of host-plant origin since this capacity to liberate ammonia is lost in the free-living state.…”

Section: Discussionsupporting

confidence: 81%

The Cyanophyte‐hepatic Symbiosis Ii. Nitrogen Fixation and the Interchange of Nitrogen and Carbon

Stewart

Rodgers

1977

New Phytologist

View full text Add to dashboard Cite

SUMMARYFree-living and symbiotic phycobionts of Anthoceros punctatus and Blasia pusilla reduce acetylene and fix '^N2; gametophytes and sporophytes without algae do not. Nitrogenase activity by free-living and symbiotic Nostoc is higher under microaerobic than aerobic conditions in the light, and is higher in the light than in the dark. The free-living Blasia phycobiont grows heterotrophically on sucrose and less well on fructose and glucose; heterotrophic growth on galactose is negligible. There is a transfer of ^^N from the alga, via the gametophyte to the sporophyte of Anthoceros. About 98% of the extracellular nitrogen liberated into the medium by excised Nostoc colonies is in the form of ammonia; there is negligible liberation of peptides and amino acids. The capacity to excrete ammonia is lost after 72 h of growth free from the liverwort. Excised Nostoc colonies show a negligible capacity to fix CO2 photosynthetically and autoradiographic studies show a transfer of fixed carbon from Blasia gametophytes to the algal cavities. Sucrose may be the main extracellular carbon compound liberated by Blasia gametophytes. In Anthoceros, nitrogenase activity can be sustained for days when alga-containing gametophytes are placed in the dark, if the sporophytes remain exposed to the light. This indicates a transfer of photosynthate from the sporophyte, via the gametophyte, to the alga.

show abstract

Section: Discussionsupporting

confidence: 81%

The Cyanophyte‐hepatic Symbiosis Ii. Nitrogen Fixation and the Interchange of Nitrogen and Carbon

Stewart

Rodgers

1977

New Phytologist

View full text Add to dashboard Cite

show abstract

“…The occurrence of the lag in reactivation suggests that a component formed in the light is involved in the activating process. MSX (an inhibitor of glutamine synthetase; Stewart & Rowell, 1975) and acetylene (which competitively inhibits nitrogen fixation) allowed higher levels of acetylene reduction to continue in the latter part of the light period. Both of these compounds will reduce the amount of nitrogen available for assimilation, although by two different mechanisms.…”

Section: Discussionmentioning

confidence: 99%

Regulation of nitrogenase activity in relation to the light-dark regime in the filamentous non-heterocystous cyanobacterium Trichodesmium sp. NIBB 1067

Ohki

Zehr

Fujita

1992

Journal of General Microbiology

View full text Add to dashboard Cite

A periodicity in nitrogen fixation potential with respect to the light-dark regime was studied in the filamentous non-heterocystous cyanobacterium Trichodesmium sp. NIBB 1067. During a 12 h light/l2 h dark cycle, potential nitrogenase activity measured by acetylene reduction in the light was insignificant in the dark period, but developed after illumination for 1 to 3 h. Maximum nitrogenase activity was found at the middle of the light period, and activity decreased near the end of the light period. Manipulation of the length of the light and dark periods, and use of the glutamine synthetase inhibitor L-methionine sulphoximine, led to the conclusion that (1) the periodicity in activity was not attributable to an endogenous rhythm, (2) development and maintenance of nitrogenase activity in Trichodesmium was regulated by the light period, and (3) the decrease in activity at the end of the light period was due to the accumulation of an intermediate(s) in nitrogen metabolism. The nitrogenase Fe-and MoFe-proteins were always present despite the changes in nitrogenase activity associated with the light-dark cycle. However, a change in apparent molecular mass of the Fe-protein on SDS-PAGE correlated with the change in nitrogenase activity. The results indicate that changes of nitrogenase activity in Trichodesmium under a light-dark regime can be attributed to activation and deactivation of the Fe-protein, and that the activation of the protein depends on light.

show abstract

“…Previously, we have provided evidence based on enzyme studies (Dharmawardene et al, 1973;Rowell et al, 1977), the use of analogues (Stewart & Rowell, 1975;Ladha et al, 1978) and I5N tracer studies that glutamine synthetase is a major enzyne involved in NH4+ assimilation in N,-fixing cyanobacteria. This conclusion is also supported by other work (Wolk et al, 1976;Meeks et al, 1977;Ownby, 1977;Thomas et al, 1977) and there is now substantial evidence that the glutamine synthetase/glutamate synthase pathway (see, for example, Brown et al, 1974) is the primary route of NH4+ assimilation in N,-fixing cyanobacteria.…”

mentioning

confidence: 94%

Purification and some Properties of Glutamine Synthetase from the Nitrogen-fixing Cyanobacteria Anabaena cylindrica and a Nostoc sp.

Sampaio

Rowell

Stewart

1979

Journal of General Microbiology

Self Cite

134

View full text Add to dashboard Cite

Glutamine synthetase has been purified to homogeneity from two N,-fixing cyanobacteria, Anabaena cylindrica and a species of Nostoc (the phycobiont of Peltigera canina). The activities of the A . cylindrica enzyme in the biosynthetic and transferase assays were, respectively, 9-4 and 32 pmol product formed min-l (mg protein)-l; the corresponding values for the Nostoc sp. enzyme were 6.5 and 20. Stabilization of the enzyme required Mg2+, glutamate, EDTA and a thiol reagent to be present during purification.The molecular weight of the A. cylindrica enzyme was 59 1000 as estimated by sedimentation analysis, 660000 by gel filtration and 565000 by polyacrylamide gel electrophoresis; the Nostoc sp. enzyme gave values of 630000 by gel filtration and 575000 by electrophoresis. The molecular weights of the sub-units of each enzyme were approximately 49000 to 50 000. Electron microscopy revealed that each molecule was composed of 12 sub-units arranged in two superimposed hexagonal rings. The maximum diameter of the rings was 13-6 nm and the distance between the centres of adjacent sub-units was 4.9 nm.When dialysed in the absence of stabilizing ligands the A . cylindrica enzyme lost activity and the protein band characteristic of the native enzyme was replaced by three bands with approximate molecular weights of 510000, 310000 and 130000. These sub-species reassociated and activity was restored by adding 2-mercaptoethanol and substrates. A similar reversible deactivation has been observed with glutamine synthetase from photosynthetic eukaryotes and yeast but no similar data have been reported for a N,-fixing prokaryote.

show abstract

Effects of L-methionine-DL-sulphoximine on the assimilation of newly fixed NH3, acetylene reduction and heterocyst production in Anabaena cylindrica

Cited by 259 publications

References 13 publications

The Cyanophyte‐hepatic Symbiosis Ii. Nitrogen Fixation and the Interchange of Nitrogen and Carbon

The Cyanophyte‐hepatic Symbiosis Ii. Nitrogen Fixation and the Interchange of Nitrogen and Carbon

Regulation of nitrogenase activity in relation to the light-dark regime in the filamentous non-heterocystous cyanobacterium Trichodesmium sp. NIBB 1067

Purification and some Properties of Glutamine Synthetase from the Nitrogen-fixing Cyanobacteria Anabaena cylindrica and a Nostoc sp.

Contact Info

Product

Resources

About