Heterocyst Metabolism and Development

Wölk, C. Peter; Ernst, Anneliese; Elhai, Jeff

doi:10.1007/0-306-48205-3_27

Cited by 120 publications

(200 citation statements)

References 389 publications

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“…strain PCC 7120, nitrogen deficiency leads to the development of specialized cells called heterocysts that protect nitrogenase against inactivation by O 2 [9], however, elevated O 2 partial pressures remain harmful to nitrogenase activity to some extent [6,10e12]. The enzyme activity is induced during the late stages of heterocyst differentiation and then declines in a rather short time (usually less than several hours) under ambient air or N 2 , because its product ammonia meets the nitrogen nutritional requirements of the cells and consequently suppresses de novo nitrogenase synthesis [9].…”

Section: Introductionmentioning

confidence: 99%

Sustained photobiological hydrogen production in the presence of N2 by nitrogenase mutants of the heterocyst-forming cyanobacterium Anabaena

Masukawa

Hausinger

Inoue

2014

International Journal of Hydrogen Energy

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Hydrogen productionBiofuel Nitrogenase Site-directed mutagenesis a b s t r a c t Heterocyst-forming cells of the cyanobacterium Anabaena sp. strain PCC 7120 DHup, lacking an uptake hydrogenase, photobiologically produce H 2 by nitrogenase. Under N 2 -rich atmosphere, the nitrogenase activity declines in a rather short time due to the sufficiency of combined nitrogen. From the parental DHup strain, site-directed double-crossover variants, dc-Q193S and dc-R284H, were created with amino acid substitutions presumed to be located in the vicinity of the FeMo-cofactor of nitrogenase. Unlike the case for the DHup strain, H 2 production activities of the variants were not decreased by the presence of high concentrations of N 2 and they continuously produced H 2 over 21 days with occasional headspace gas replacement. This property of N 2 insensitivity is a potentially useful strategy for reducing the cost of the culture gas in future practical applications of sustainable biofuel production. This Anabaena strain has only the Mo-containing nitrogenase which reduces acetylene to ethylene, but the dc-Q193S variant also produced ethane at low but measurable rates along with greater rates of ethylene production.

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Section: Introductionmentioning

confidence: 99%

Sustained photobiological hydrogen production in the presence of N2 by nitrogenase mutants of the heterocyst-forming cyanobacterium Anabaena

Masukawa

Hausinger

Inoue

2014

International Journal of Hydrogen Energy

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“…or related strains are subjected to combined-nitrogen step-down, some of the vegetative cells of the filaments differentiate into heterocysts, which gain the capacity of nitrogen fixation but lose the function of CO 2 fixation. Thus, an active exchange of assimilated carbon and nitrogen occurs between both cell types (Wolk et al 1994). In these cyanobacteria, both global nitrogen control and heterocyst differentiation is mainly exerted by Nitrogen control A (NtcA), a transcriptional activator of the CAP family, which binds to the consensus sequence GTN 10 AC (Herrero et al 2004).…”

Section: Introductionmentioning

confidence: 99%

Sucrose synthase and RuBisCo expression is similarly regulated by the nitrogen source in the nitrogen-fixing cyanobacterium Anabaena sp.

Curatti

Giarrocco²,

Salerno³

2005

Planta

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In higher plants and cyanobacteria, sucrose (Suc) metabolism is carried out by a similar set of enzymes. The function and regulation of Suc metabolism in cyanobacteria has begun to be elucidated. In strains of Anabaena sp., filamentous nitrogen-fixing cyanobacteria, Suc synthase (SuS, EC 2.4.1.13) controls Suc cell level through the cleavage of the disaccharide. The present work shows that there are two sus genes in Anabaena (Nostoc) sp. that are co-regulated regarding the nitrogen source; however, only susA accounts for the extractable SuS activity and for the control of the Suc level. Primer extension analysis has uncovered the sequence of the Anabaena susA and susB ammonium-activated putative promoters, which share a high sequence similarity with that of rbcLS encoding ribulose bisphosphate carboxylase/oxygenase (EC 4.1.1.39) and other ammonium up-regulated genes. Moreover, susA and rbcLS expression is developmentally co-localized to the vegetative cells of the nitrogen-fixing cyanobacterial filaments. Our results strongly suggest the existence of a regulatory network that would coordinate the expression of key genes for Suc and nitrogen metabolism, carbon fixation, and development in Anabaena sp.

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“…They consist of large strings of cells formed mainly by vegetative cells in which photosynthesis takes place alternated every 10 to 20 cells by one heterocyst in which the nitrogen fixation takes place. 90 The acetylene (C 2 H 2 ) reduction method is commonly used to follow the process of nitrogen fixation. 91 As for N 2 , the triple bond of acetylene is broken and reduced to ethylene (C 2 H 4 ) 92 which can be detected very sensitively with laser photoacoustics.…”

Section: Microbiologymentioning

confidence: 99%

Photoacoustic Spectroscopy in Trace Gas Monitoring

Harren

Mandon

Cristescu

2000

Encyclopedia of Analytical Chemistry

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Since ancient times people have searched for ways to understand processes occurring in the environment, atmosphere or living organisms. Study of the gaseous trace compounds present may shed new light on chemical reactions taking place in the atmosphere or biochemical reactions inside organisms such as plants, animals and human beings. This article presents photoacoustic spectroscopy as a sensitive, on‐line and noninvasive tool for monitoring the concentration of trace gases. Following a short introduction and a historic overview, attention is focused on the description of devices and equipment which determine the detection limits and selectivity. An overview is given of the current detection limits for photoacoustic detection. Applications are discussed with emphasis on environmental monitoring (in ambient air, car exhaust and stack gas emission), on medical applications and on biological applications (in postharvest physiology, plant physiology, microbiology and entomology).

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Heterocyst Metabolism and Development

Cited by 120 publications

References 389 publications

Sustained photobiological hydrogen production in the presence of N2 by nitrogenase mutants of the heterocyst-forming cyanobacterium Anabaena

Sustained photobiological hydrogen production in the presence of N2 by nitrogenase mutants of the heterocyst-forming cyanobacterium Anabaena

Sucrose synthase and RuBisCo expression is similarly regulated by the nitrogen source in the nitrogen-fixing cyanobacterium Anabaena sp.

Photoacoustic Spectroscopy in Trace Gas Monitoring

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