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  • Blue-green alga  (1)
  • Cyanobacterium  (1)
  • Heterocyst and nitrogenase  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Genetic control of heterocyst formation in the blue-Green algae Nostoc muscorum and nostoc linckia (1977)
    Springer
    Archives of microbiology 114 (1977), S. 155-159 
    Details
    ISSN: 1432-072X
    Keywords: Blue-green algae ; Nostoc ; Mutants ; Heterocyst and nitrogenase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Non-heterocystous, non-nitrogenfixing (het - nif-), heterocystous, non-nitrogenfixing (het + nif-) and multiple heterocystous, nitrogen-fixing (M-het + nif+) mutants of heterocystous, nitrogen-fixing (het + nif+) wild-type Nostoc muscorum and Nostoc linckia were isolated and characterized with respect to (a) nitrogenfixing activity, (b) reversion frequency, (c) ammonium repressibility of heterocyst formation, (d) heterocyst spacing pattern, and (e) action of L-methionine-DL-sulphoximine (MSO), an inhibitor of glutamine synthetase (GS), on heterocyst regulation. The mutant and revertant results suggest: (i) either involvement of a common genetic determinant in the formation of heterocyst and nitrogenase or the organization of het genes and nif genes in a single operon prone to complete inactivation by a single polar mutation, (ii) non-participation of active nitrogenase in regulation of heterocyst spacing; (iii) involvement of genetic factor(s) in the control of heterocyst spacing pattern in N. linckia, and (iv) apparently different nature of the mechanism of heterocyst inhibition by proheterocyst from that of heterocyst inhibition by NO 3 - or NH 4 + . L-Methionine-DL-sulphoximine inhibits growth and causes heterocyst formation in chains in N. linckia growing in nitrogen-free, NO 3 - , NO 2 - or NH 4 + medium, thus indicating a close physiological linkage between heterocyst and inorganic nitrogen metabolism regulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00410777
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    An azide-resistant mutant of the blue-green algaNostoc muscorum producing heterocyst and nitrogenase in the presence of fixed inorganic nitrogen source (1978)
    Springer
    Archives of microbiology 119 (1978), S. 197-201 
    Details
    ISSN: 1432-072X
    Keywords: Blue-green alga ; Nostoc ; Azide-resistant mutant ; Heterocyst and Nitrogenase regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The N2, NO 3 − , NO 2 − , NH 4 + and glutamine growing cultures of parentNostoc muscorum are found more or less equally sensitive to azide inhibition of growth. A mutant strain resistant to sodium azide was isolated from the parent strain in NO 3 − medium and the two strains were compared with regard to their heterocyst formation and nitrogenase activity in NO 3 − , NO 2 − , NH 4 + and glutamine media. While the parent strain stops production of both heterocyst and nitrogenase in all the fixed nitrogen media, the azide resistant strain forms both in the fixed inorganic nitrogen media but only heterocyst and no nitrogenase in the glutamine medium. Clearly a single genetic determinant of regulatory nature appears to mediate azide-resistance as well as relief of heterocyst and nitrogenase formation from inhibition by the fixed inorganic nitrogen source. The results of glutamine effect on the heterocyst and nitrogenase formation of the two strains indicate the operation of two levels of glutamine-sensitive regulation, one which operates through the common genetic determinant of heterocyst and nitrogenase regulation and the other exclusive to nitrogenase regulation. The in vivo functional nitrogenase does not appear to be the reason for azide-resistance and neither ammonia nor glutamine or its close metabolic product seems to function in the control of heterocyst spacing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00964273
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Genetic transformation of glutamine auxotrophy to prototrophy in the cyanobacterium Nostoc muscorum (1990)
    Springer
    Archives of microbiology 154 (1990), S. 414-416 
    Details
    ISSN: 1432-072X
    Keywords: Cyanobacterium ; Ammonium assimilation ; Glutamine auxotrophy ; Transformation ; MSX-resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Glutamine auxotrophic (Gln -) and l-methionine d,l-sulfoximine (MSX) resistant (MSX r) mutants of N. muscorum were isolated and characterized for nitrogen nutrition, nitrogenase activity, glutamine synthetase (GS) activity and glutamine amide, α-keto-glutarate amido transferase (GOGAT) activity. The glutamine auxotroph was found to the GOGAT-containing GS-defective, incapable of growth with N2 or NH 4 + but capable of growth with glutamine as nitrogen source, thus, suggesting GS to be the primary enzyme of both ammonia assimilation and glutamine formation in the cyanobacterium. The results of transformation and reversion studies suggests that glutamine auxotrophy is the result of a mutation in the gln A gene and that gln A gene can be transferred from one strain to another by transformation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00276541
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    Paper (German National Licenses)
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