Mechanisms of temperature acclimatisation in the psychrotolerant green alga Coccomyxa subellipsoidea C-169 (Trebouxiophyceae).

Despite the interest in different temperature acclimatisations of higher plants, few studies have considered the mechanisms that allow psychrotolerant microalgae to live in a cold environment. Although the analysis of the genomes of some algae revealed the presence of specific genes that encode enzymes that can be involved in the response to stress, this area has not been explored deeply. This work aims to clarify the acclimatisation mechanisms that enable the psychrotolerant green alga Coccomyxa subellipsoidea C-169 to grow in a broad temperature spectrum.

How Light Modulates the Growth of Cells by Changing the Function of Phycobilisomes.

The aim of this study was to examine how light intensity and quality affect the photosynthetic apparatus of cells by modulating the structure and function of phycobilisomes. Cells were grown in equal amounts of white, blue, red, and yellow light of low (LL) and high (HL) intensity. Biochemical characterization, fluorescence emission, and oxygen exchange were used to investigate selected cellular physiological parameters.

How Light Reactions of Photosynthesis in C4 Plants Are Optimized and Protected under High Light Conditions.

Most C4 plants that naturally occur in tropical or subtropical climates, in high light environments, had to evolve a series of adaptations of photosynthesis that allowed them to grow under these conditions. In this review, we summarize mechanisms that ensure the balancing of energy distribution, counteract photoinhibition, and allow the dissipation of excess light energy. They secure effective electron transport in light reactions of photosynthesis, which will lead to the production of NADPH and ATP.

The effect of temperature conditions during growth on the transformation frequency of obtained by electroporation.

In this study, we have shown that transformation efficiency of C-169 obtained by electroporation can be significantly increased by either supra- or sub-optimal growth temperatures.

Stable transformation of unicellular green alga Coccomyxa subellipsoidea C-169 via electroporation.

In this study, we have shown the applicability of electroporation and hygromycin B as a convenient selectable marker for stable nuclear transformation of Coccomyxa subellipsoidea C-169. Since it is the first sequenced eukaryotic microorganism from polar environment, this offers unique opportunities to study adaptation mechanisms to cold.

PEG-mediated, Stable, Nuclear and Chloroplast Transformation of .

The ability to achieve nuclear or chloroplast transformation in plants has been a long standing goal, especially in microalgae research. Over past years there has been only little success, but transient and stable nuclear transformation has been achieved in multiple species. Our newly developed method allows for relatively simple transformation of in both nuclear and chloroplast genome by means of homologous recombination between the genome and a transformation vector.

Deletion of psbQ' gene in Cyanidioschyzon merolae reveals the function of extrinsic PsbQ' in PSII.

We have successfully produced single-cell colonies of C. merolae mutants, lacking the PsbQ' subunit in its PSII complex by application of DTA-aided mutant selection. We have investigated the physiological changes in PSII function and structure and proposed a tentative explanation of the function of PsbQ' subunit in the PSII complex.

Differences in photosynthetic responses of NADP-ME type C4 species to high light.

Three species chosen as representatives of NADP-ME C4 subtype exhibit different sensitivity toward photoinhibition, and great photochemical differences were found to exist between the species. These characteristics might be due to the imbalance in the excitation energy between the photosystems present in M and BS cells, and also due to that between species caused by the penetration of light inside the leaves. Such regulation in the distribution of light intensity between M and BS cells shows that co-operation between both the metabolic systems determines effective photosynthesis and reduces the harmful effects of high light on the degradation of PSII through the production of reactive oxygen species (ROS).

Transformation of the Cyanidioschyzon merolae chloroplast genome: prospects for understanding chloroplast function in extreme environments.

We have successfully transformed an exthemophilic red alga with the chloramphenicol acetyltransferase gene, rendering this organism insensitive to its toxicity. Our work paves the way to further work with this new modelorganism. Here we report the first successful attempt to achieve a stable, under selectable pressure, chloroplast transformation in Cyanidioschizon merolae-an extremophilic red alga of increasing importance as a new model organism.

Chloramphenicol acetyltransferase-a new selectable marker in stable nuclear transformation of the red alga Cyanidioschyzon merolae.

In this study, we have shown the applicability of chloramphenicol acetyltransferase as a new and convenient selectable marker for stable nuclear transformation as well as potential chloroplast transformation of Cyanidioschyzon merolae-a new model organism, which offers unique opportunities for studding the mitochondrial and plastid physiology as well as various evolutionary, structural, and functional features of the photosynthetic apparatus.

The short-term response of Arabidopsis thaliana (C3) and Zea mays (C4) chloroplasts to red and far red light.

Light quality has various effects on photochemistry and protein phosphorylation in Zea mays and Arabidopsis thaliana thylakoids due to different degrees of light penetration across leaves and redox status in chloroplasts. The effect of the spectral quality of light (red, R and far red, FR) on the function of thylakoid proteins in Zea mays and Arabidopsis thaliana was investigated. It was concluded that red light stimulates PSII activity in A.

Metabolic responses to lead of metallicolous and nonmetallicolous populations of Armeria maritima.

Metabolic responses to Pb(NO₃)₂ (Pb) ions of excised leaves of metallicolous (MPs) and nonmetallicolous populations (NMPs) of Armeria maritima, cultivated on normal soil, were examined. Detached leaves were exposure to Pb for 24 h, and metabolic parameters were investigated. Pb decreased the photosynthesis (Pn) rate and photosystem II (PSII) activity, whereas the photochemical efficiency of PSII remained unchanged.

Light intensity and quality stimulated Deg1-dependent cleavage of PSII components in the chloroplasts of maize.

Recent studies have revealed that photo damages inducing high white light illumination of C3-type plant Arabidopsis thaliana promotes Deg1-mediated degradation of not only photosystem II core proteins D1/D2 but also minor LHCII proteins CP26, CP29 and PSII-associated PsbS protein. Using biochemical and immunological approaches we show that that the substrate pool of the heterologously expressed Deg1 ortholog protease from C4-type plant Zea mays is very similar to that of the A. thaliana in both mesophyll and bundle sheath chloroplasts.

Tandem multiplication of the IS26-flanked amplicon with the bla(SHV-5) gene within plasmid p1658/97.

The IncF plasmid p1658/97 (c. 125 kb) from Escherichia coli isolates recovered during a clonal outbreak in a hospital in Warsaw, Poland, in 1997 contains the extended-spectrum β-lactamase (ESBL) gene bla(SHV-5), originated from the Klebsiella pneumoniae chromosome. A region containing the bla(SHV-5) gene is flanked by two IS26 copies and its copy number multiplies spontaneously within p1658/97 and RecA-deficient E.

Phosphorylation of PSII proteins in maize thylakoids in the presence of Pb ions.

Lead is potentially toxic to all organisms including plants. Many physiological studies suggest that plants have developed various mechanisms to contend with heavy metals, however the molecular mechanisms remain unclear. We studied maize plants in which lead was introduced into detached leaves through the transpiration stream.

High light stimulates Deg1-dependent cleavage of the minor LHCII antenna proteins CP26 and CP29 and the PsbS protein in Arabidopsis thaliana.

The chloroplast Deg1 protein performs proteolytic cleavage of the photodamaged D1 protein of the photosystem II (PSII) reaction center, PSII extrinsic subunit PsbO and the soluble electron carrier plastocyanin. Using biochemical, immunological and mass spectrometry approaches we showed that the heterogeneously expressed Deg1 protease from Arabidopsis thaliana can be responsible for the degradation of the monomeric light-harvesting complex antenna subunits of PSII (LHCII), CP26 and CP29, as well as PSII-associated PsbS (CP22/NPQ4) protein. The results may indicate that cytochrome b (6) protein and two previously unknown thylakoid proteins, Ptac16 and an 18.

Differential turnover of the photosystem II reaction centre D1 protein in mesophyll and bundle sheath chloroplasts of maize.

Photoinhibition is caused by an imbalance between the rates of the damage and repair cycle of photosystem II D1 protein in thylakoid membranes. The PSII repair processes include (i) disassembly of damaged PSII-LHCII supercomplexes and PSII core dimers into monomers, (ii) migration of the PSII monomers to the stroma regions of thylakoid membranes, (iii) dephosphorylation of the CP43, D1 and D2 subunits, (iv) degradation of damaged D1 protein, and (v) co-translational insertion of the newly synthesized D1 polypeptide and reassembly of functional PSII complex. Here, we studied the D1 turnover cycle in maize mesophyll and bundle sheath chloroplasts using a protein synthesis inhibitor, lincomycin.

High light induced accumulation of two isoforms of the CF1 alpha-subunit in mesophyll and bundle sheath chloroplasts of C4 plants.

The effect of light irradiance on the amount of ATP synthase alpha-subunit in mesophyll (M) and bundle sheath (BS) chloroplasts of C(4) species such as maize (Zea mays L., type NADP-ME), millet (Panicum miliaceum, type NAD-ME) and guinea grass (Panicum maximum, type PEP-CK) was investigated in plants grown under high, moderate and low light intensities equal to 800, 350 and 50 micromol photons m(-2) s(-1), respectively. The results demonstrate that alpha-subunit of ATP synthase in both M and BS chloroplasts is altered by light intensity, but differently in the investigated species.