scholarly journals Heavy Metal Stress Alters the Response of the Unicellular Cyanobacterium Synechococcus elongatus PCC 7942 to Nitrogen Starvation

Life ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 275
Author(s):  
Khaled A. Selim ◽  
Michael Haffner
Keyword(s):  
Heavy Metal ◽  
Nitrogen Starvation ◽  
Heavy Metal Stress ◽  
Synechococcus Elongatus ◽  
Metal Stress ◽  
Unicellular Cyanobacterium ◽  
Combined Nitrogen ◽  
Diazotrophic Cyanobacteria ◽  
Synechococcus Elongatus Pcc 7942 ◽  
Pcc 7942

Non-diazotrophic cyanobacteria are unable to fix atmospheric nitrogen and rely on combined nitrogen for growth and development. In the absence of combined nitrogen sources, most non-diazotrophic cyanobacteria, e.g., Synechocystis sp. PCC 6803 or Synechococcus elongatus PCC 7942, enter a dormant stage called chlorosis. The chlorosis process involves switching off photosynthetic activities and downregulating protein biosynthesis. Addition of a combined nitrogen source induces the regeneration of chlorotic cells in a process called resuscitation. As heavy metals are ubiquitous in the cyanobacterial biosphere, their influence on the vegetative growth of cyanobacterial cells has been extensively studied. However, the effect of heavy metal stress on chlorotic cyanobacterial cells remains elusive. To simulate the natural conditions, we investigated the effects of long-term exposure of S. elongatus PCC 7942 cells to both heavy metal stress and nitrogen starvation. We were able to show that elevated heavy metal concentrations, especially for Ni2+, Cd2+, Cu2+ and Zn2+, are highly toxic to nitrogen starved cells. In particular, cells exposed to elevated concentrations of Cd2+ or Ni2+ were not able to properly enter chlorosis as they failed to degrade phycobiliproteins and chlorophyll a and remained greenish. In resuscitation assays, these cells were unable to recover from the simultaneous nitrogen starvation and Cd2+ or Ni2+ stress. The elevated toxicity of Cd2+ or Ni2+ presumably occurs due to their interference with the onset of chlorosis in nitrogen-starved cells, eventually leading to cell death.

scholarly journals Self-replicating shuttle vectors based on pANS, a small endogenous plasmid of the unicellular cyanobacterium Synechococcus elongatus PCC 7942

Microbiology ◽  
2016 ◽  
Vol 162 (12) ◽  
pp. 2029-2041 ◽  
Author(s):  
You Chen ◽  
Arnaud Taton ◽  
Michaela Go ◽  
Ross E. London ◽  
Lindsey M. Pieper ◽  
...  
Keyword(s):  
Synechococcus Elongatus ◽  
Unicellular Cyanobacterium ◽  
Shuttle Vectors ◽  
Synechococcus Elongatus Pcc 7942 ◽  
Pcc 7942

scholarly journals Alanine Dehydrogenase Activity Is Required for Adequate Progression of Phycobilisome Degradation during Nitrogen Starvation in Synechococcus elongatus PCC 7942

2006 ◽  
Vol 188 (14) ◽  
pp. 5258-5265 ◽  
Author(s):  
Roxane Lahmi ◽  
Eleonora Sendersky ◽  
Alexander Perelman ◽  
Martin Hagemann ◽  
Karl Forchhammer ◽  
...  
Keyword(s):  
Dehydrogenase Activity ◽  
Cellular Response ◽  
Nitrogen Starvation ◽  
Synechococcus Elongatus ◽  
Wild Type ◽  
Sulfur Starvation ◽  
Alanine Dehydrogenase ◽  
In The Wild ◽  
Synechococcus Elongatus Pcc 7942 ◽  
Pcc 7942

ABSTRACT Degradation of the cyanobacterial light-harvesting antenna, the phycobilisome, is a general acclimation response that is observed under various stress conditions. In this study we identified a novel mutant of Synechococcus elongatus PCC 7942 that exhibits impaired phycobilisome degradation specifically during nitrogen starvation, unlike previously described mutants, which exhibit aberrant degradation under nitrogen, sulfur, and phosphorus starvation conditions. The phenotype of the new mutant, AldΩ, results from inactivation of ald (encoding alanine dehydrogenase). AldΩ is deficient in transcription induction of a number of genes during nitrogen starvation. These genes include the “general nutrient stress-related” genes, nblA and nblC, the products of which are essential for phycobilisome degradation. Furthermore, transcripts of several specific nitrogen-responsive genes accumulate at lower levels in AldΩ than in the wild-type strain. In contrast, ald inactivation did not decrease the accumulation of transcripts during sulfur starvation. Transcription of ald is induced upon nitrogen starvation, which is consistent with the ability of wild-type cells to maintain a low cellular content of alanine under these conditions. Unlike wild-type cells, AldΩ accumulates alanine upon nitrogen starvation. Our analyses suggest that alanine dehydrogenase activity is necessary for an adequate cellular response to nitrogen starvation. Decomposition of alanine may be required to provide a sufficient amount of ammonia. Furthermore, the accumulated alanine, or a related metabolite, may interfere with the cues that modulate acclimation during nitrogen starvation. Taken together, our results provide novel information regarding cellular responses to nitrogen starvation and suggest that mechanisms related to nitrogen-specific responses are involved in modulation of a general acclimation process.

Isolation Of PS II Nanoparticles And Oxygen Evolution Studies In Synechococcus Spp. PCC 7942 Under Heavy Metal Stress

2009 ◽  
Author(s):  
Iffat Zareen Ahmad ◽  
Shanthy Sundaram ◽  
Ashutosh Tripathi ◽  
K. K. Soumya ◽  
M. R. Singh ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Oxygen Evolution ◽  
Heavy Metal Stress ◽  
Metal Stress ◽  
Ps Ii ◽  
Pcc 7942

scholarly journals Role of calcium in acclimation of the cyanobacterium Synechococcus elongatus PCC 7942 to nitrogen starvation

Microbiology ◽  
2009 ◽  
Vol 155 (1) ◽  
pp. 25-34 ◽  
Author(s):  
Francisco Leganés ◽  
Karl Forchhammer ◽  
Francisca Fernández-Piñas
Keyword(s):  
Nitrogen Starvation ◽  
Transcriptional Regulator ◽  
Synechococcus Elongatus ◽  
Signal Suppression ◽  
Intracellular Ca ◽  
Step Down ◽  
Synechococcus Elongatus Pcc 7942 ◽  
Pcc 7120 ◽  
Pcc 7942

A Ca2+ signal is required for the process of heterocyst differentiation in the filamentous diazotrophic cyanobacterium Anabaena sp. PCC 7120. This paper presents evidence that a transient increase in intracellular free Ca2+ is also involved in acclimation to nitrogen starvation in the unicellular non-diazotrophic cyanobacterium Synechococcus elongatus PCC 7942. The Ca2+ transient was triggered in response to nitrogen step-down or the addition of 2-oxoglutarate (2-OG), or its analogues 2,2-difluoropentanedioic acid (DFPA) and 2-methylenepentanedioic acid (2-MPA), to cells growing with combined nitrogen, suggesting that an increase in intracellular 2-OG levels precedes the Ca2+ transient. The signalling protein PII and the transcriptional regulator NtcA appear to be needed to trigger the signal. Suppression of the Ca2+ transient by the intracellular Ca2+ chelator N,N′-[1,2-ethanediylbis(oxy-2,1-phenylene)]bis[N-[2-[(acetyloxy)methoxy]-2-oxoethyl]]-,bis[(acetyloxy)methyl] ester (BAPTA-AM) inhibited expression of the glnB and glnN genes, which are involved in acclimation to nitrogen starvation and transcriptionally activated by NtcA. BAPTA-AM treatment partially inhibited expression of the nblA gene, which is involved in phycobiliprotein degradation following nutrient starvation and is regulated by NtcA and NblR; in close agreement, BAPTA-AM treatment partially inhibited bleaching following nitrogen starvation. Taken together, the results presented here strongly suggest an involvement of a defined Ca2+ transient in acclimation of S. elongatus to nitrogen starvation through NtcA-dependent regulation.

scholarly journals Transcriptome landscape of Synechococcus elongatus PCC 7942 for nitrogen starvation responses using RNA-seq

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Sun Young Choi ◽  
Byeonghyeok Park ◽  
In-Geol Choi ◽  
Sang Jun Sim ◽  
Sun-Mi Lee ◽  
...  
Keyword(s):  
Nitrogen Starvation ◽  
Synechococcus Elongatus ◽  
Rna Seq ◽  
Synechococcus Elongatus Pcc 7942 ◽  
Pcc 7942
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