[LIGHT-DEPENDENT SYNTHESIS OF CELL MEMBRANES IN THE Brc-1 MUTANT OF CHLAMYDOMONAS REINHARDTII].

The structural organization of cells of the Brc-1 mutant of the unicellular green algae Chlamydomonas reinhardtii grown in the light and in the dark has been studied. The Brc-1 mutant contains the brc-1 mutation in the nucleus gene LTS3. In the light, all membrane structures in mutant cells form normally and are well developed. In the dark under heterotrophic conditions, the mutant cells grew and divided well, however, all its cell membranes: plasmalemma, tonoplast, mitochondrial membranes, membranes of the nucleus shell and chloroplast, thylakoids, and the membranes of dictiosomes of the Golgi apparatus were not detected. In the dark under heterotrophic conditions, mutant cells well grow and divide. It were shown that a short-term (1-10 min) exposure of Brc-1 mutant cells to light leads to the restoration of all above-mentioned membrane structures. Possible reasons for the alterations of membrane structures are discussed.

[Valve-like structures in motor cells of the leaf of Distichlis spicata "Yesen 4A" (Poaceae)].

The salt gland of the leaf of Distichlis directly contacts the cells of interfascicular aquiferous parenchyma (motor cells). The cytoplasmic strand of motor cells produce deep invaginations, which form with the participation of mitochondria. The constriction of the cytoplasmic strand at the site of the localization of mitochondria leads to the fusion of the tonoplast and plasmalemma with mitochondrial membranes and the formation of a thin one-layer plate, a valve. At this locus, vacuolar and apoplast spaces are separated only by a valve. The cytoplasm of motor cells is filled with electron dense granules, which are considered as contractile elements. It is assumed that the cytoplasmic strand is involved in the reduction of the volume, which results in the generation of pressure on the valve. This leads to the direct throw-in of water into the apoplast space adjacent to the salt gland.

[Ultrastructural organization and composition of carotenoids in the eyespot in the mutant Chlamydomonas reinhardtii].

Biogenesis of the ultrastructure of the eyespot in the chloroplasts of unicellular green algae Chlamydomonas reinhardtii has been studied. We have found that the development of the structure of the eyespot correlates with the accumulation of carotenoids. Depending on their accumulation, the eyespots form from 1 to 4 lines of lipid-carotenoid globules. It has been shown that only carotenes are accumulated in the globules of the eyespots. We first have found that the composition of carotenes in the eyespots of the mutants may vary due to the changes in their composition in the membranes of chloroplasts.

[Structural-functional organization of the cells of Brc-1 mutant Chlamydomonas reinhardtii, supplying protoporphyrin IX in the dark].

The structural-functional characteristics of the cells of wild type CC-124 and Brc-1 mutant of the unicellular green algae Chlamydomonas reinhardtii while growing in the dark and light were studied. It has been shown that the cells of the wild type in heterotrophic and mixotrophic growth conditions had a well developed structure and high functional activity due to the ability of the cells to synthesize chlorophyll both in the light and in the dark. The cells of Brc-1 mutant lost their ability to synthesize chlorophyll in the dark and the cells' color was orange due to brc-1 mutation in the nuclear gene LTS3 that regulated the activity of Mg-chelatase enzyme. In the dark the mutant cells accumulated protoporphyrin IX and had a weakly developed structure with low functional activity. It has been ascertained that due to high content of protoporphyrin IX even a short-term exposure of the cells of Brc-1 mutant to the light was accompanied by very strong destructive changes in all the membranes in a cell: plasmalemma, chloroplast, mitochondrion, shells of the nucleus and vacuoles. The reasons of these significant damages of the membrane components and O2-gas exchange in the cells of Brc-1 mutant are discussed.

[Comparative analysis of the exogenous ammonium influence on soybean tissue and Chlamydomonas cells].

In this work we studied the influence of exogenous ammonium on the total protein and chlorophyll contents, on the number of ribosomes and on the expression of ribosomal genes encoding the small subunit 18S rRNA and rpS6 protein in unicellular green alga Chlamydomonas reinhardtii and in callus tissue of Glycine max. Comparative analysis of two sets of data showed that although the lack of ammonium resulted in reduction of the number of ribosomes in alga and plant cells, this effect was not caused by decreasing of the expression level of the ribosomal genes. Possible mechanisms of the ammonium regulatory role in the ribosome biogenesis are discussed.

[The "crystals" in the sugar beet (Beta vulgaris L.) leaves].

Crystal containing cells widely distributed in plant tissues, though the origin of the crystals and their functions are still opened to question. Membrane vesicles in beet leaves are visible in electronic microscope. They originate in cytoplasm and penetrate into vacuole by pinocytosis with participation of tonoplast. In light microscope, vesicles are luminous likewise crystals in crystal cells. Such vesicles-"crystals" fulfill crystal cells also. The content of vesicles-"crystals" are electronic transparent at every path of leaf development. It was proposed that distinct vesicles-"crystals" in cytoplasm and vacuole and mass of them in crystal cells, vein bundles, and epidermal cells--all of them are lytic compartments. Later, obviously, true crystals are formed.

[Structural-functional organization of chloroplasts in leaves of xantha-702 mutant of Gossypium hirsutum L].

For cotton mutant xantha (Gossypium hirsutum L.), it has been established that synthesis of 5-aminolevulinic acid was blocked in the light. In the light this mutant accumulates chlorophyll by 30 times lower as compared to the parent type. In mutant xantha, a very few pigment-protein complexes of PS-I and PS-II are formed in chloroplasts, and formation of membrane system in these is blocked at the early stages, in most cases, at the stage of bubbles and single short thylakoids. Functional activity of reaction centers of PS-I and PS-II is close to zero. Only light-harvesting chlorophyll-a/b protein complexes of the two photosystems are formed in mutant xantha plastid membranes with maximum chlorophyll fluorescence at 728 and 681 nm, respectively. It has been concluded that in mutant xantha genetic block of 5-aminolevulinic acid biosynthesis in the light disturbs the formation and functioning of the complexes of reaction centers of PS-I and PS-II, hindering the development of the whole membrane system in chloroplasts, causing a sharp decrease in productivity.

[Electron dense substance of thylakoids in chloroplasts of tansy Tanacetum vulgare L].

An intrathylakoid electron opaque substance, further referred to as loculin, is found in 80-90 % of thylakoids of tansy leaf mesophyll chloroplasts at the stage of flower bud formation and flowering. Upon conventional isolation of chloroplasts in aqueous solution, and fixation in osmium solution alone, loculin is not retained in thylakoids. Preliminary fixation of leaves in glutaraldehyde makes it possible to isolate chloroplasts without injuring the envelope and stroma (glutar chloroplasts), and loculin is retained in thylakoids under these conditions. Upon prolonged incubation of glutar chloroplasts (for 24 h), loculin leaves thylakoids in the form of drops concentrating on the chloroplast envelope. Upon crossing the thylakoid membrane and chloroplast, loculin properties remain unchanged. It is assumed that loculin is an important metabolite necessary for active growth.

[The influence of ammonium and nitrate of nutrient medium on ultrastructural organization and photosynthesis of callus cells in Glycine max L]. / Vliianie ammoniia i nitrata pitatel'noi sredy na ul'trastrukturnuiu organizatsiiu i fotosintez kletok kallusa Glycine max L.

We studied the influence of exogenic ammonium on the functional activity and ultrastructural organization of cells of the mixotrophic soybean callus (Glycine max L.). Ammonium available in the nutrient medium increased the chlorophyll content, accelerating the rate of photosynthetic O2 evolution per unit of biomass. The presence of ammonium in the medium promoted formation of the protein-synthesizing system, which manifested itself as increased numbers of ribosomes, and thylakoids of chloroplasts, and higher electron density of the stroma in mitochondria and cytoplasm of mixotrophic cells. It has been concluded that the use of ammonium may lead to activation of protein synthesis, thus rising photosynthetic activity and favouring formation and development of membrane structures in chloroplasts.

[Ultrastructure organization of chloroplasts in chlorotica mutants of Pisum sativum L]. / Ul'trastrukturnaia organizatsiia khloroplastov chlorotica-mutantov Pisum sativum L.

A study was made of chlorophyll-protein complexes of photosystems, and of ultrastructural organization of chloroplasts in pea leaves of the primary cultivar Torsdag and of its mutants, chlorotica 2004 and 2014. It has been shown that mutants accumulated 80 and 55% chlorophyll, respectively, and were able to synthesize all four types of photosystem complexes. The value of the light-harvesting antenna in mutant 2014 was close to the control one, and in mutant 2004 it increased significantly (by 30%). These changes were caused by a proportional decrease (40-50%) in any complexes in mutant 2014, whereas the number of PS-I reaction centre complexes, decreased by 50% in mutant 2004 at nearly complete storage of PS-I reaction centre complexes, decreased by 50% in mutant 2004 at nearly complete storage of PS-II complexes. The proportional decrease of PS-I and PS-II complexes in mutant chlorotica 2014 was followed by partial reduction of the entire membrane system in chloroplasts, but with a normal development of both granal and intergranal thylakoids. On the contrary, the loss of PS-I reaction centre complexes in mutant chlorotica 2004 leads to reduction of unstacked sites of thylakoids in chloroplasts. It is concluded that this effect may be associated with localization of PS-I complexes mainly in unstacked sites of thylakoids.

[Structural and functional organization of chloroplasts in leaves of Pisum sativum L. under conditions of root hypoxia and iron deficiency]. / Strukturno-funktsional'naia organizatsiia khloroplastov v list'iakh Pisum sativum L. v usloviiakh kornevoi gipoksii i defitsita zheleza.

A combined effect of iron deficiency and root hypoxia on the biochemical composition activity and structure of chloroplasts in pea leaves have been studied. Both factors are shown to affect the accumulation of chlorophyll causing leaf chlorosis. At iron deficiency chlorosis occurs from the top of plant leaves. At root hypoxia chlorosis starts from the lower strata. At a combined action of both factors the destructive effects are summarized. It was established that light-harvesting complexes of photosystems were reduced stronger at iron deficiency, while complexes of reaction centers of photosystem I and photosystem II are lessened at root hypoxia. Nevertheless, even at a combined effect of both factors yellow leaves preserved small amounts of any pigment-protein complexes and their functional activities. The ultrastructure of chloroplasts during leaf chlorosis was gradually reduced. At first, intergranal sites of thylakoids and then granal ones were destroyed, that was typical of iron deficiency. However, even yellow and almost white leaves kept small thylakoids, capable of forming stacking and small grana made of 2-3 thylakoids. It has been concluded that the destructive effects are summarized due to different kinds of action of iron deficiency and root hypoxia on the structure and functioning of leaves at their combined action.

[Choline chloride effect on chloroplast ultrastructure and cell growth in Chlamydomonas reinhardtii]. / Ul'trastruktura khloroplastov i rost kletok Chlamydomonas reinhardtii pri deistvii kholinkhlorida.

The influence of growth retardant choline chloride (0.02, 0.2 and 2 g/l) on cell size and division as well as chlorophyll accumulation and chloroplast ultrastructure of unicellular green algae Chlamydomonas was studied. It was shown that at any concentration used (0.02, 0.2, and 2 g/l) choline chloride decreased the rate of cell division. The content of chlorophyll and carotenoid per cell decreased and the sizes of cells increased at all concentrations of choline chloride. On the basis of electron microscopy data, the conclusion was made that an increase in the concentration of choline chloride intensified destruction processes in membranes of chloroplasts and other cell organelles.

Groups of bonds determining the configuration of the thylakoid system.

Four groups of bonds determining the configuration of the thylakoid system have been established. The hypothesis presented here postulates the following. 1. There exist continuous lateral protein-protein interactions (bonds) all over the thylakoid membrane. 2. Lateral protein bonds are subdivided into two independent groups - lateral bonds of outer and inner membrane leaflets. 3. The configuration of a single thylakoid is determined by the mutual action of lateral and interlumenal bonds of the inner membrane leaflet, and the configuration of the thylakoid system of a chloroplast is determined by the mutual action of lateral and intermembrane (stacking) bonds of the outer membrane leaflet.

Light-induced reversible local fusions of thylakoid membranes in the presence of dibucaine or tetracaine.

The dynamics of structural changes in pea chloroplasts in the presence of 25-50 microM dibucaine or tetracaine has been examined using electron microscopy. The light-induced uptake of anesthetic cations by thylakoids is attended by the appearance of local fusions of stroma-exposed thylakoid membranes. The first membrane protrusions and interthylakoid contacts are observed after 4 s illumination and they become numerous by 10 s. As a result, a network of anastomoses is formed which is maintained during at least 10 min. These effects are reversible in the dark and can be reproduced several times. The formation of membrane fusions is inhibited by the addition of protonophore. It is supposed that the energy-dependent uptake of protonated anesthetics by thylakoids leads to an increase in positive surface charge and thus a lateral pressure on the inner side of the thylakoid membrane. The appearance of membrane protrusions (crinkles) having the positive curvature of their inner surface may be considered as a way of compensating for lateral pressure. Presumably, anastomoses result from the fusion of crinkles to adjacent thylakoids.

[Changes in the intervertebral disks in disorders of segmental blood supply of the spine]. / Izmenenie mezhpozvonochnogo diska pri narushenii segmentarnogo krovosnabzheniia pozvonochnika.

In 50 mature Chinchilla rabbits a model of chronic insufficiency of blood supply in the lumbar vertebral bodies has been disturbed as a result of unilateral sectioning of the segmentary arteries and veins. By means of light and transmissive electron microscopy the dynamics of structural changes has been followed in tissue of the intervertebral discs for 3 months after the operative intervention. Under hypoxia in the ground substance of the pulposus++ nucleus even proteoglycans granular-filamentous network gradually develops and floccular material and transverse striated filamentous aggregates are accumulated. Notochord cells are subjected to certain degenerative changes and die. Simultaneously fibroblastic cells of the pulposus++ nucleus periphery become activated, they produce glycosaminoglycans and collagen. As a result the hydrated tissue of the pulposus++ nucleus is substituted for a newly formed fibrous cartilage. The process of fibroses in the intervertebral disc is completed in 3 months after blood circulation has been disturbed in the vertebral bodies.

[Extra- and intraorganic blood channel of the rabbit lumbar vertebrae in health and after cutting the segmentary arteries and veins]. / Ekstra- i intraorgannoe krovenosnoe ruslo poiasnichnykh pozvonkov krolikov v norme i pri pererezke segmentarnykh arterii i ven.

Extra- and intraorganic blood bed of the lumbar vertebrae has been investigated by means of the cast method and vital injection of the vessels with Indian ink-gelatin mixture and subsequent serial translucent preparations. Existence of constant topographo-anatomical relations has been stated between the segmentary arteries and veins with the lumbar vertebrae. Peculiarities in spatial organization of the microcirculatory bed have been revealed in different zones of the vertebral body, as well as peculiarity of blood supply of the epiphyseal osseous marginal plate. Topography and localization of changes in the intraorganic vertebral blood bed have been studied under conditions of bilateral crossing of the segmentary vascular fasciculi at the level of one, two and three vertebrae. Compensatory resources of the vertebral column blood bed are discussed, when large extra-organic trunks in the lumbar part are damaged.

[Reversible changes in the volume of isolated mitochondria in the course of ion flux oscillations between the mitochondria and the medium]. / Obratimye izmeneniia ob"ema izolirovannykh mitokhondrii v khode kolebanii ionnykh potokov mezhdu mitokhondriiami i sredoi.

Glutaraldehyde has been used for electron microscopic studies of mitochondrial volume fluctuation during Sr2+--induced oscillation of ion fluxes. It has been shown that the observed ultrastructural and fluctuations of mitochondria is reversible to correlate with light-scattering value as well as to the direction of ion transfer. Determination of the intramitochondrial volume at different stages of oscillatory cycle shows the increase in the volume during the process of swelling up to 2.4-5.6 times compared with the shrihkate state.