Synechococcus
Dotaz
Zobrazit nápovědu
Cyanobacteria are among the most important primary producers on the Earth. However, the evolutionary forces driving cyanobacterial species diversity remain largely enigmatic due to both their distinction from macro-organisms and an undersampling of sequenced genomes. Thus, we present a new genome of a Synechococcus-like cyanobacterium from a novel evolutionary lineage. Further, we analyse all existing 16S rRNA sequences and genomes of Synechococcus-like cyanobacteria. Chronograms showed extremely polyphyletic relationships in Synechococcus, which has not been observed in any other cyanobacteria. Moreover, most Synechococcus lineages bifurcated after the Great Oxidation Event, including the most abundant marine picoplankton lineage. Quantification of horizontal gene transfer among 70 cyanobacterial genomes revealed significant differences among studied genomes. Horizontal gene transfer levels were not correlated with ecology, genome size or phenotype, but were correlated with the age of divergence. All findings were synthetized into a novel model of cyanobacterial evolution, characterized by serial convergence of the features, that is multicellularity and ecology.
- MeSH
- biologická evoluce * MeSH
- DNA bakterií genetika MeSH
- fylogeneze MeSH
- genom bakteriální * MeSH
- molekulární sekvence - údaje MeSH
- přenos genů horizontální * MeSH
- RNA ribozomální 16S genetika MeSH
- sekvenční analýza DNA MeSH
- sekvenční seřazení MeSH
- Synechococcus klasifikace genetika MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The Black Sea is the largest meromictic sea with a reservoir of anoxic water extending from 100 to 1000 m depth. These deeper layers are characterised by a poorly understood fluorescence signal called "deep red fluorescence", a chlorophyll a- (Chl a) like signal found in deep dark oceanic waters. In two cruises, we repeatedly found up to 103 cells ml-1 of picocyanobacteria at 750 m depth in these waters and isolated two phycoerythrin-rich Synechococcus sp. strains (BS55D and BS56D). Tests on BS56D revealed its high adaptability, involving the accumulation of Chl a in anoxic/dark conditions and its capacity to photosynthesise when re-exposed to light. Whole-genome sequencing of the two strains showed the presence of genes that confirms the putative ability of our strains to survive in harsh mesopelagic environments. This discovery provides new evidence to support early speculations associating the "deep red fluorescence" signal to viable picocyanobacteria populations in the deep oxygen-depleted oceans, suggesting a reconsideration of the ecological role of a viable stock of Synechococcus in dark deep waters.
- MeSH
- chlorofyl a metabolismus MeSH
- ekosystém MeSH
- fluorescence MeSH
- fotosyntéza MeSH
- fykoerythrin metabolismus MeSH
- fylogeneze MeSH
- genom bakteriální MeSH
- oceány a moře MeSH
- Synechococcus chemie klasifikace izolace a purifikace metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Černé moře MeSH
- oceány a moře MeSH
The carbon-concentrating mechanisms (CCMs) of cyanobacteria counteract the low CO2 affinity and CO2:O2 selectivities of the Rubisco of these photolithotrophs and the relatively low oceanic CO2 availability. CCMs have a significant energy cost; if light is limiting, the use of N sources whose assimilation demands less energy could permit a greater investment of energy into CCMs and inorganic C (Ci) assimilation. To test this, we cultured Synechococcus sp. UTEX LB 2380 under either N or energy limitation, in the presence of NO3- or NH4+. When growth was energy-limited, NH4+-grown cells had a 1.2-fold higher growth rate, 1.3-fold higher dissolved inorganic carbon (DIC)-saturated photosynthetic rate, 19% higher linear electron transfer, 80% higher photosynthetic 1/K1/2(DIC), 2.0-fold greater slope of the linear part of the photosynthesis versus DIC curve, 3.5-fold larger intracellular Ci pool, and 2.3-fold higher Zn quota than NO3--grown cells. When energy was not limiting growth, there were not differences between NH4+- and NO3--grown cells, except for higher linear electron transfer and larger intracellular Ci pool.We conclude that, when energy limits growth, cells that use the cheaper N source divert energy from N assimilation to C acquisition and assimilation; this does not happen when energy is not limiting.
The assimilation of N-NO3- requires more energy than that of N-NH4+ . This becomes relevant when energy is limiting and may impinge differently on cell energy budget depending on depth, time of the day and season. We hypothesize that N-limited and energy-limited cells of the oceanic cyanobacterium Synechococcus sp. differ in their response to the N source with respect to growth, elemental stoichiometry and carbon allocation. Under N limitation, cells retained almost absolute homeostasis of elemental and organic composition, and the use of NH4+ did not stimulate growth. When energy was limiting, however, Synechococcus grew faster in NH4+ than in NO3- and had higher C (20%), N (38%) and S (30%) cell quotas. Furthermore, more C was allocated to protein, whereas the carbohydrate and lipid pool size did not change appreciably. Energy limitation also led to a higher photosynthetic rate relative to N limitation. We interpret these results as an indication that, under energy limitation, the use of the least expensive N source allowed a spillover of the energy saved from N assimilation to the assimilation of other nutrients. The change in elemental stoichiometry influenced C allocation, inducing an increase in cell protein, which resulted in a stimulation of photosynthesis and growth.
- MeSH
- adenosintrifosfát metabolismus MeSH
- amoniové sloučeniny farmakologie MeSH
- bakteriální proteiny metabolismus MeSH
- biomasa MeSH
- dusičnany farmakologie MeSH
- dusík metabolismus MeSH
- energetický metabolismus * účinky léků MeSH
- fosfor metabolismus MeSH
- fotosyntéza účinky léků MeSH
- kyslík metabolismus MeSH
- lipidy analýza MeSH
- sacharidy analýza MeSH
- síra metabolismus MeSH
- Synechococcus cytologie účinky léků růst a vývoj metabolismus MeSH
- uhlík metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
The aim and novelty of this paper are found in assessing the influence of inhibitors and antibiotics on intact cell MALDI-TOF mass spectra of the cyanobacterium Synechococcus sp. UPOC S4 and to check the impact on reliability of identification. Defining the limits of this method is important for its use in biology and applied science. The compounds included inhibitors of respiration, glycolysis, citrate cycle, and proteosynthesis. They were used at 1-10 μM concentrations and different periods of up to 3 weeks. Cells were also grown without inhibitors in a microgravity because of expected strong effects. Mass spectra were evaluated using controls and interpreted in terms of differential peaks and their assignment to protein sequences by mass. Antibiotics, azide, and bromopyruvate had the greatest impact. The spectral patterns were markedly altered after a prolonged incubation at higher concentrations, which precluded identification in the database of reference spectra. The incubation in microgravity showed a similar effect. These differences were evident in dendrograms constructed from the spectral data. Enzyme inhibitors affected the spectra to a smaller extent. This study shows that only a long-term presence of antibiotics and strong metabolic inhibitors in the medium at 10-5 M concentrations hinders the correct identification of cyanobacteria by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF).
- MeSH
- antibakteriální látky toxicita MeSH
- antimycin A analogy a deriváty toxicita MeSH
- azidy toxicita MeSH
- buněčné dýchání účinky léků MeSH
- chloramfenikol toxicita MeSH
- citrátový cyklus účinky léků MeSH
- deoxyglukosa toxicita MeSH
- fluoracetáty toxicita MeSH
- glykolýza účinky léků MeSH
- malonáty toxicita MeSH
- proteosyntéza účinky léků MeSH
- pyruváty toxicita MeSH
- reprodukovatelnost výsledků MeSH
- spektrometrie hmotnostní - ionizace laserem za účasti matrice metody MeSH
- stav beztíže MeSH
- streptomycin toxicita MeSH
- Synechococcus chemie účinky léků izolace a purifikace metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- MeSH
- DNA MeSH
- reakce na tepelný šok MeSH
- sinice enzymologie genetika MeSH
- Publikační typ
- srovnávací studie MeSH
