scholarly journals Chloroplast ultrastructure in leaves of Cucumis sativus chlorophyll mutant

2014 ◽  
Vol 52 (2) ◽  
pp. 131-137 ◽  
Author(s):  
Irena Palczewska ◽  
Barbara Gabara ◽  
Eugienia Mikulska ◽  
Bogusław Kubicki
Keyword(s):  
Cucumis Sativus ◽  
Control Plant ◽  
Chloroplast Ultrastructure ◽  
Normal Structure ◽  
Membrane System ◽  
Lamellar System ◽  
Electron Dense Material ◽  
Young Leaves ◽  
Chlorophyll Mutants ◽  
Irregular Arrangement

The developing and young leaves of <em>Cucumis sativus</em> chlorophyll mutants are yellow, when mature they become green and do not differ in their colour from those of control plants. The mesophyll of yellow leaves contains a diversiform plastid population with a varying degree of defectiveness, which is mainly manifested in the reduction or disorganization of the typical thylakoid system. DNA areas, ribosome-like particles and aggregates of electron-dense material are preserved in the stroma of mutated plastids. Starch grains are deficient. Apart from mutated plastids, chloroplasts with a normal structure, as in control plants, were also observed.The leaf greening process is accompanied by a reconstruction and rearrangement of the inner chloroplast lamellar system and an ability to accumulate starch. However, in the mutant chloroplasts as compared with control-plant ones, an irregular arrangement of grana and reduced number of inter-grana thylakoids can be seen. An osmiophilic substance stored in the stroma of mutated plastids and the vesicles formed from an internal plastid membrane take part in restoration of the membrane system.

Changes in photosynthetic apparatus of mustard (Sinapis alba) cotyledons following cycloheximide and kinetin treatments

Biologia ◽  
2008 ◽  
Vol 63 (5) ◽  
Author(s):  
Adriana Machlicová ◽  
L’udmila Slováková ◽  
Ján Hudák
Keyword(s):  
Photosynthetic Pigments ◽  
Structural Characteristics ◽  
Photosynthetic Apparatus ◽  
Chloroplast Ultrastructure ◽  
Membrane System ◽  
Sinapis Alba ◽  
Negative Effects ◽  
Chlorophyll Pigments ◽  
Leaf Mesophyll ◽  
Rubisco Subunits

AbstractBiochemical and accompanying structural characteristics of the photosynthetic process were studied in mustard seedlings cultivated on medium with increasing concentrations of cycloheximide alone as well as in combination with various kinetin concentrations. After 7 days of cultivation the contents of total chlorophyll, carotenoids and content of Rubisco in mustard cotyledons were determined. The content of chlorophyll pigments and carotenoids decreased in dependence of cycloheximide concentration. Following antibiotic treatment the content of both Rubisco subunits markedly decreased. In addition cycloheximide caused disturbance in mesophyll organization and chloroplast ultrastructure.Kinetin applied with cycloheximide increased the amount of photosynthetic pigments as well as of Rubisco, compared to the cycloheximide alone. In the seedlings treated with cycloheximide+kinetin the structure of leaf mesophyll and chloroplast membrane system was similar to control. Our results indicate that kinetin diminished the negative effects of cycloheximide on photosynthetic pigments and Rubisco as well as on the structural traits of the cotyledons.

Croissance, activité peroxydasique et modifications ultrastructurales induites par le cadmium dans la racine de tomate

2002 ◽  
Vol 80 (9) ◽  
pp. 942-953 ◽  
Author(s):  
Wahbi Djebali ◽  
Wided Chaïbi ◽  
Mohamed Habib Ghorbel
Keyword(s):  
Metal Accumulation ◽  
Root Apex ◽  
Membrane System ◽  
Editorial Staff ◽  
Tomato Plants ◽  
Electron Dense Material ◽  
Meristematic Cells ◽  
Vesicular Membrane ◽  
Root Tissues ◽  
Oxidative State

Accumulation of Cd in the organs of young tomato plants (Lycopersicon esculentum var. Ibiza F1), as well as its effects on growth, peroxidasic activity, and root ultrastructure were evaluated. Plants previously cultivated in a basic nutrient solution and then treated for 10 days with different concentrations of CdCl2 (0, 5, 10, 20, 50, 100 μM) accumulated high quantities of cadmium in their root tissues and showed reduced growth. Increased peroxidasic activity observed at this level reflects a state of oxidative stress induced by cadmium. An ultrastructural study of the root apex showed a strong vacuolization in the meristematic cells as well as deposition of electron-dense material in vacuoles and plastids. On either side of the cell wall, a medullated-like and (or) vesicular membrane system developed over a significant periplasmic space. Results suggest an endocellular metal accumulation leading to a disorganization of membrane systems, probably related to the onset of an oxidative state of stress.Key words: cadmium, tomato, peroxidases, ultrastructure, root.[Translated by editorial staff]

scholarly journals Membrane distribution in dividing endosperm cells of Haemanthus.

1982 ◽  
Vol 94 (3) ◽  
pp. 637-643 ◽  
Author(s):  
W T Jackson ◽  
B G Doyle
Keyword(s):  
Mitotic Spindle ◽  
Osmium Tetroxide ◽  
Membrane System ◽  
Potassium Ferrocyanide ◽  
Polar Regions ◽  
Chromosome Movement ◽  
Prominent Feature ◽  
Cell Organelles ◽  
Electron Dense Material

Membranes in cell-wall-free dividing endosperm cells of Haemanthus were examined after postfixation with osmium tetroxide-potassium ferrocyanide. We found that preservation and staining of membranes in metaphase cells was highly variable. Even adjacent cells often showed different degrees of preservation of membrane. However, this method does reveal a much more extensive membrane system in the mitotic spindle of Haemanthus than has been revealed previously using glutaraldehyde-osmium fixation. At prometaphase a system of membranes becomes associated with the kinetochore bundles. By metaphase, membranes constitute a prominent feature of kinetochore bundles, terminating near the kinetichores. Minipoles, identified by converging microtubules and associated membranes, are distributed in a zone extending laterally across the polar regions of the cell. The microtubules appear to terminate at the minipoles, whereas the membrane system becomes oriented generally perpendicular to the spindle axis and interfaces distally with a region of amorphous electron-dense material, helical polyribosomes, and cell organelles. The role of this extensive membrane system, if any, in chromosome movement is unknown. However, its distribution is coincident with the distribution of calcium-rich membranes and kinetochore fibers at metaphase in these cells (Wolniak, S. M., P. K. Hepler, and W. T. Jackson, 1981, Eur. J. Cell Biol., 25:171-174). Thus, these membranes may function in creating calcium domains that, in turn, may play a regulatory role in chromosome movement.

Ultrastructural Changes of Tobacco Chloroplasts Induced by Pyriclor

Weed Science ◽  
1970 ◽  
Vol 18 (1) ◽  
pp. 48-53 ◽  
Author(s):  
J. Geronimo ◽  
J. W. Herr
Keyword(s):  
Nicotiana Tabacum ◽  
Phaseolus Vulgaris ◽  
Chloroplast Ultrastructure ◽  
Membrane System ◽  
Chloroplast Envelope ◽  
Ultrastructural Changes ◽  
Complete Disappearance ◽  
Chloroplast Structure ◽  
Spherical Form ◽  
Shape And Size

Treatment of tobacco (Nicotiana tabacumL., var. NC-402) with 2,3,5-trichloro-4-pyridinol (pyriclor) leads to progressive disruption of chloroplast ultrastructure. Initial changes include the inception of a spherical form, swelling of the fret system, and commencement of loss of starch. More advanced changes include the complete disappearance of starch, further swelling and disorganization of the fret membrane system, followed by swelling and disruption of the membranes of the granal discs and rupture of the chloroplast envelope. The changes induced by pyriclor on chloroplast ultrastructure in tobacco are analagous to those caused by 2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine (atrazine) on kidney bean (Phaseolus vulgarisL.) and barnyardgrass (Echinochloa crusgalliL. Beauv.). The shape and size of mitochondria were not altered by treatment with the chemical; however, there appeared to be a significant increase in the number of mitochondria present when alterations in chloroplast structure could be seen. The appearance of visual symptoms of phytotoxicity (chlorosis) correlated with the onset of disruptive changes in chloroplast ultrastructure.

scholarly journals The effect of ammonium ions on the activity of glutamate dehydrogenase, alanine aminotransferase and aspartate aminotransferase in Cucumis sativus L. seedlings

2014 ◽  
Vol 50 (3) ◽  
pp. 429-436
Author(s):  
Genowefa Kubiak-Dobosz
Keyword(s):  
Glutamate Dehydrogenase ◽  
Cucumis Sativus ◽  
Aspartate Aminotransferase ◽  
Alanine Aminotransferase ◽  
Ammonium Ions ◽  
Cucumis Sativus L ◽  
Factors Affecting ◽  
Cucumber Seedlings ◽  
Young Leaves ◽  
Medium Activity

Changes in the activity of glutamate dehydrogenase (GDH), alanine aminotransferase (GPT) and aspartate aminotransferase (GOT) were studied in various organs of <em>Cucumis sativus</em> L. seedlings in relation to the uptake of mineral nitrogen (in form of N0<sub>3</sub><sup>-</sup> or NH<sub>4</sub><sup>+</sup> ) from the medium. Activity of GDH, GPT, and GOT was higher in young leaves and roots of cucumber seedlings if the plants developed- in an ammonium medium. No similar changes of aminotransferases activity were noted in the cotyledons. Factors affecting varying effect of ammonium ions upon GPT and GOT activity are discussed for particular organs of cucumber seedlings.

The localization of (3H) thymidine incorporation in the DNA of replicating spinach chloroplasts by electron-microscope autoradiography

1976 ◽  
Vol 20 (2) ◽  
pp. 341-355
Author(s):  
R.J. Rose ◽  
J.V. Possingham
Keyword(s):  
Grain Size ◽  
Electron Microscope ◽  
Thymidine Incorporation ◽  
Membrane System ◽  
Chloroplast Envelope ◽  
Lamellar System ◽  
Electron Microscope Autoradiography ◽  
Spinach Chloroplasts ◽  
Microscope Autoradiography ◽  
Leaf Disks

Electron-microscope autoradiography has been used to obtain information on the localization of DNA labelled with [3H]thymidine in chloroplasts known to be replicating and concomitantly synthesizing and segregating DNA, in cultured leaf disks. The studies were made using both Microdol-X developer and a ‘compact’ developer which gave a smaller grain size. About 80% of the grains were associated with the granal membranes and with presumptive DNA regions (3-nm fibril material in clear areas). Few grains occurred in association with the chloroplast envelope. We suggest that the DNA of chloroplasts is associated with the grana lamellae and extends into the stroma. Some light-microscope autoradiographs of whole chloroplasts show spiral or helical-like labelling patterns. We interpret these patterns as demonstration of the possibility that DNA occurs along the length of a continuous lamellar membrane system. Chloroplast fractionation experiments provided data consistent with the electron-microscope autoradiographic studies as most of the label was associated with chlorophyll-containing lamellae. We consider an association of chloroplast DNA molecules along the length of a continuous lamellar system would ensure an orderly segregation of DNA to daughter chloroplasts, during the binary fission of spinach chloroplasts by constriction division.

scholarly journals Influence of nitrogen deficiency on photosynthesis and chloroplast ultrastructure of pepper plants (Research Note)

2001 ◽  
Vol 10 (1) ◽  
pp. 59-64 ◽  
Author(s):  
S. DONCHEVA ◽  
V. VASSILEVA ◽  
G. IGNATOV
Keyword(s):  
Plant Biomass ◽  
Nitrogen Deficiency ◽  
Weight Ratio ◽  
Chloroplast Ultrastructure ◽  
Biomass Accumulation ◽  
Dry Weight ◽  
Membrane System ◽  
Nitrogen Deprivation ◽  
Shoot Dry Weight ◽  
Pepper Plants

Pepper plants (Capsicum annuum L. cv. Zlaten Medal) were grown on nutrient solution without nitrogen, and photosynthetic response of plants was examined by determination of leaf CO2 fixation and chlorophyll and carotenoid contents. The absence of nitrogen in the medium resulted in a decrease of the leaf area and of plant biomass accumulation, and in an increase of the root-shoot dry weight ratio. The photosynthetic activity and chlorophyll and carotenoid contents decreased significantly under nitrogen deprivation. Examination of nitrogen deficient leaves by transmission electron microscopy showed dramatic changes in chloroplast ultrastructure. The proportion of starch granules and plastoglobules in the stroma matrix was increased and internal membrane system was greatly reduced. It seems that nitrogen plays an important role in the formation of chloroplast structure and hence to the photosynthetic intensity and productivity of pepper plants.

Ontogenesis of corneal surface ultrastructure in nocturnal Lepidoptera

1971 ◽  
Vol 262 (843) ◽  
pp. 343-363 ◽  
Keyword(s):  
Light And Electron Microscopy ◽  
Spatial Relationship ◽  
Membrane System ◽  
The Body ◽  
Corneal Surface ◽  
Surface Ultrastructure ◽  
New Material ◽  
Body Cuticle ◽  
The One ◽  
Irregular Arrangement

The morphogenesis of epicorneal structures in nocturnal Lepidoptera was studied with light and electron microscopy. During the first 4-5 days after pupation, microvilli (with their tips hexagonally distributed) arose gradually from the corneagenous cell surface. At the time of onset of moulting (about 5 days after pupation), patches of lamellar elements appeared distal to the tips of the microvilli. There was one patch for each microvillus from which the patch was separated by a narrow cleft. The cleft was traversed by a few thin bridges which seemed to originate in the microvillus. The bridges were interpreted to be extracellular continuations of intramicrovillar filaments and to insert on the proximal surface of the patch. At about 5 1/2 days after pupation, the patches were seen to be composed of two outer electron-dense lines and a less distinct, inner and thicker dense line. The patches bulged markedly, their concavity turned towards the microvillar tip. A number of discrete bridges extended between the microvillus and the base of the patch, which now appeared as a low dome. The bases of the domer later coalesced to form a continuous lamellar 'membrane' system ( epicorneal lamina , ECL), and the concavity of the domes increased, forming successively deeper lamina evagmations (LE) which strictly retained their spatial relationship to the tips of the microvilli (MV) throughout the ontogenesis. Growth of the ECL evaginations to form an array of successively higher cupoles—and, finally, the complete nipple anlage-was suggested to take place by addition of new material at all points of the LE surface within the palisade of MV/LE bridges. The latter were proposed to act as structures of constraint preventing the ECL to buckle randomly and causing the evaginations to develop in a regular fashion. The results were compared with those described in reports on the morphogenesis of the body cuticle of insects. It was proposed that different types of corneal surface protuberances (corneal nipples of various heights; low protrusions in regular or irregular arrangement) as well as some types of surface lpturing in the body cuticle of insects may be produced on the basis of the same mechanism as the one described for the formation of the full-sized nipples of nocturnal Lepidoptera

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