Showing papers by "Antonia Herrero published in 1991"

Control of Nitrogenase mRNA Levels by Products of Nitrate Assimilation in the Cyanobacterium Anabaena sp. Strain PCC 7120.

Abstract: Nitrate inhibited nitrogenase synthesis and heterocyst development in the cyanobacterium Anabaena sp. strain PCC 7120. Inhibition of dinitrogen fixation by nitrate did not take place, however, in nitrate reductase-deficient derivatives of this strain. Hybridization of total RNA isolated from cells grown on different nitrogen sources with an internal fragment of the nifD gene showed that regulation of nitrogenase activity by nitrate is exerted through a negative control of the nitrogenase mRNA levels.

Sequence-specific endonucleases from the cyanobacterium Nostoc sp. ATCC 29132.

Abstract: The nitrogen-fixing cyanobacterium Nostoc sp. ATCC 29132 was shown to contain two sequence-specific endonucleases. Nsp(29132) I was an isoschizomer of AsuII, and Nsp(29132) II was an isoschizomer of BamHI. Nsp(29132) II was shown to generate ends that could be ligated to those generated by BamHI.

Regulation of Nitrogen Assimilation in the Cyanobacterium Synechococcus

Abstract: Synechococcus is a unicellular cyanobacterium able to assimilate nitrate, nitrite or ammonium. Cellular elements involved in the assimilation of these compounds are subjected to repression by ammonium. Ammonium also promotes an immediate inhibition of the nitrate transport system. We have recently identified a gene (ntcA) whose product appears to be required for the expression of genes subjected to repression by ammonium. Mutants that constitutively express elements of the nitrate assimilation system have also been reported, suggesting that negative regulatory elements might also be involved in the control of nitrogen assimilation in Synechococcus.