Effects of slow clinorotation on lipid contents and proton permeability of thylakoid membranes of pea chloroplasts.

Photochemical characteristics and lipid composition of thylakoid membranes from 12 day-old pea leaves that were exposed to slow clino-rotation were examined and compared with a vertical control. Proton permeability of thylakoid membranes was estimated from light-induced proton uptake (delta H+) and post-illumination proton efflux in chloroplast suspensions. The delta pH magnitude was calculated from the level of light-induced quenching of 9-aminoacridine fluorescence. Proton permeability of thylakoid membranes increased during exposure to clino-rotation. When subsequently transferred to darkness, proton efflux increased almost 2-fold in clinorotated leaves. The results were compared with data on pigment and polar lipid composition of photosynthetic membranes in clino-rotated and control plants. It was concluded that both the increase of proton permeability and the decrease of polar lipid content in chloroplasts were induced by clino-rotation.

[Identification and localization of virus RNA in pepper (Capsicum anuum L.) chloroplasts by means of the PCR method]. / Identifikatsiia i opredelenie lokalizatsii virusnoi RNK v khloroplastakh pertsa (Capsicum annuum L.) metodom polimeraznoi tsennoi reaktsii.

Localization of virus RNA in stroma of Capsicum anuum L. chloroplasts was determined by the PCR method. Accumulation of virus protein in the membranes and stroma of infected pepper chloroplasts has been studied. It is concluded that the virus protein synthesis takes place in the pepper chloroplasts.

[Effect of tobacco mosaic virus on the ultrastructure of leaf mesophyll cells of the pepper Capsicuum anuum L]. / Vliianie virusa tabachnoi mozaiki na ul'trastrukturu kletok mezofilla lista pertsa Capsicuum anuum L.

Chlorotic areas of Capsicuum anuum L. leaves infected with tobacco mosaic virus (TMV) have been investigated. Pathological changes of chloroplasts were found out. Swelling, more osmophilic plastoglobuli, loosened thylakoid structure were observed. It was shown that chloroplasts did not take part in the process of virus replication. Some structural changes of mitochondria were discovered too. They were most tolerant to the virus infection in comparison with other organoids.

Influence of clinorotation on some parameters of photosynthetic apparatus.

This study aimed to examine the electron transport rates in the thylakoids, isolated from leaves of pea plants grown under clinorotation and in vertical control, to measure the chlorophyll a/b (Chl a/b) ratio in such thylakoids and in photosystem I (PSI) particles isolated from them, to elucidate if there are any differences in changes of PS II activity in thylakoids and Chl a/b ratio in PS I particles under phosphorylation of polypeptides of thylakoid pigment-protein complexes.

[Functions and localization of nucleotide-binding sites of CF1-ATPase using dialdehyde derivatives of ADP and ATP]. / Issledovanie funktsii i lokalizatsii nukleotidsviazyvaiushchikh tsentrov CF1-ATPazy s pomoshch'iu dial'degidnykh proizvodnykh ADP i ATP.

The covalent binding of dialdehyde derivatives of ATP and ADP (o-ATP and o-ADP) results in inactivation of chloroplast CF1-ATPase, the degree of inactivation being increased at a rise in temperature and pH. o-ADP causes predominant inhibition of the Mg2+-dependent, while o-ATP--of both Mg2+- and Ca2+-dependent activities of CF1-ATPase. The substrates and reaction products prevent the enzyme inactivation, whereas the stimulators of the Mg2+-dependent ATPase activity enhance it. The effect of these stimulators is correlated with predominant incorporation of [3H] o-nucleotide into the beta-subunit of CF1. In the absence of the stimulators o-ADP is predominantly bound to the alpha-subunit of CF1. The binding of o-ADP and o-ATP to the beta-subunit is increased in the presence of Mg2+. A comparative analysis of the labelled nucleotides incorporation into individual subunits and the changes in the catalytic and regulatory properties of the enzyme demonstrated that the catalytic and stimulator-sensitive "regulatory" sites of the enzyme are located on the beta-subunits.

The effect of microgravity on proton permeability of thylakoid membranes and contribution of II and I photosystems in photosynthetic electron transport in pea chloroplasts.

According to a number investigations microgravity conditions affect membrane apparatus of photosynthesis in cells of higher plants and alga [for review, see Kordyum et al., 1994; Kordyum, 1997]. (see for review). Chloroplasts of space-grown pea plants showed disintegration of grana, shrinkage of the membrane constituting the grana stacks and other structural perturbance of the photosynthetic membranes. However there have been no studies on the effect of microgravity on proton permeability of thylakoid membranes and closely connected with this parameter their photochemical characteristics. The aim of the study is investigation of microgravity effects on protonic permeability of photosynthetic membrane and contribution of photosystem II (PSII) and photosystem I (PSI) in electron transfer from water to potassium ferrycianide (FeCy) in isolated pea chloroplasts. Pea.

[Isolation and properties of CF1 ATPase chloroplasts with changed submolecular structure]. / Vydelenie i svoistva CF1-ATPazy s izmenennoi submolekuliarnoi Strukturoi.

An isolation procedure is worked out and properties are studied of CF1 ATPase from chloroplasts with changed submolecular structure. The enzyme, isolated by chlorophorm treatment, produced Ca-dependent ATPase activity in water solution. As compared with the enzyme isolated by well known Lien and Racker method, the enzyme preparation obtained is slightly activated by heating, is not activated by trypsin and has a lesser ability to recover ATP synthesis in EDTA-treated chloroplasts. Purification on DEAE-Sephadex produced the enzyme preparation free of delta-subunit. Chlorophorm treatment is suggested to change submolecular protein structure, in particular, loosening of the link of delta-subunit with other enzyme subunits. The data obtained suggest that delta-subunit participates in the binding of CF1 ATPase with chloroplast membrane.

[Effect of cations and protons on chloroplast and etioplast membranes]. / Deistvie kationov i protonov na membrany khloroplastov i étioplastov.

The stacking of grana and intergrana tylakoids of chloroplast, etioplast and etiochloroplast membranes was studied at various concentrations of H+ and bivalent cations. It was demonstrated that bivalent cations and H+ cause stacking of all types of the membranes tested and is not strictly correlated with the presence of a well-formed ligh-harvesting chlorophyll a/b-protein complex. In preparations of intergrana tylakoids (in contrast to those of grana tylakoids) the effects of cations was minimal. The stacking of intergrana tylakoids is more appreciable in the presence of H+ which is probably due to the peculiarities of components located on the membrane surface.