Plastid Development in Leaf Epidermis

1981 ◽  
Vol 39 ◽  
pp. 618-619
Author(s):  
Jacob P. Varkey ◽  
Mathew J. Nadakavukaren
Keyword(s):  
Leaf Development ◽  
Osmium Tetroxide ◽  
Leaf Epidermis ◽  
Plastid Development ◽  
Mesophyll Cells ◽  
Plastid Ultrastructure ◽  
Epidermal Tissue ◽  
Standard Procedures ◽  
Growth Chambers ◽  
Light:Dark Cycle

Changes in the plastid ultrastructure during development of a leaf have been studied extensively. Most studies have been done on the development of chloroplasts in mesophyll cells. Chloroplasts are small and few in number or plastids never develop into chloroplasts in epidermal cells of leaves of many species. Not much is known about the development of plastids in the epidermal tissue. Sunflower was selected to study the plastid development in the epidermal tissue.Sunflower plants were grown from seeds in growth chambers maintained on a 14:10 light:dark cycle at a daytime temperature of 78 F and nighttime temperature of 70 F with 80% humidity. Samples for ultrastructural study were taken from primary leaves at different stages of development. Because the rate of leaf development can vary from plant to plant, samples were taken from the same primary leaves of selected seedlings. These samples fixed in glutaraldehyde followed by osmium tetroxide were processed for electron microscopy using standard procedures.

scholarly journals THE STRUCTURE OF CELLS DURING TOBACCO MOSAIC VIRUS REPRODUCTION

1965 ◽  
Vol 25 (3) ◽  
pp. 77-97 ◽  
Author(s):  
L. Kolehmainen ◽  
H. Zech ◽  
D. von Wettstein
Keyword(s):  
Endoplasmic Reticulum ◽  
Tobacco Mosaic Virus ◽  
Mosaic Virus ◽  
Electron Scattering ◽  
Osmium Tetroxide ◽  
Crystal Formation ◽  
Mesophyll Cells ◽  
Virus Particles ◽  
Flexible Rods ◽  
Late Stages

The submicroscopic organization of mesophyll cells from tobacco leaves systemically infected with tobacco mosaic virus (TMV) is described. After fixation with glutaraldehyde and osmium tetroxide the arrangement of the TMV particles within the crystalline inclusions is well preserved. Only the ribonucleic acid-containing core of the virus particles is visible in the micrographs. Besides the hexagonal virus crystals, several characteristic types of "inclusion bodies" are definable in the cytoplasm: The so-called fluid crystals seem to correspond to single layers of oriented TMV particles between a network of the endoplasmic reticulum and ribosomes. Unordered groups or well oriented masses of tubes with the diameter of the TMV capsid are found in certain areas of the cytoplasm. A complicated inclusion body is characterized by an extensively branched and folded part of the endoplasmic reticulum, containing in its folds long aggregates of flexible rods. Certain parts of the cytoplasm are filled with large, strongly electron-scattering globules, probably of lipid composition. These various cytoplasmic differentiations and the different forms of presumed virus material are discussed in relation to late stages of TMV reproduction and virus crystal formation.

Effects Of Varying Salinity On Leaf Ultrastructure Of Potamogeton Pectinatus L

1999 ◽  
Vol 5 (S2) ◽  
pp. 1256-1257
Author(s):  
A.D. Barnabas ◽  
P. Bunsi ◽  
Y. Naidoo ◽  
W.J. Przybylowicz ◽  
J. Mesjasz-Przybylowicz
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Salinity ◽  
Ultrastructural Changes ◽  
Potamogeton Pectinatus ◽  
Leaf Epidermis ◽  
Leaf Ultrastructure ◽  
Low Salinity ◽  
Transmission Electron ◽  
Standard Procedures

Potamogeton pectinatus is a submerged halophyte which occurs in waters of low salinity (5% to 10%). Its upper salinity tolerance has been reported to be 19%. Reasons why P.pectinatus is unable to tolerate salinities in excess of 19%is important to our understanding of its biology. In the present study, leaf ultrastructure of plants growing at low salinity was compared with plants growing at high salinity in order to assess the effects of different salinities on the ultrastructure. Attention was focussed on ultrastructural changes occurring in the leaf epidermis, the main photosynthetic tissue.Plants were grown in seawater at two salinities : 5%(low salinity) and 20% (high salinity). Pieces of mature leaf blades from both treatments were harvested and prepared for Transmission Electron Microscopy (TEM) following standard procedures. The overall distribution and concentration of chlorine (CI) in the leaves was ascertained since this element is the most abundant anion in seawater and is important in considerations of salt tolerance in submerged halophytes.

Chemical Regulation of Plastid Development. I. Inhibition of Chlorophyll Biosynthesis in Detached Pumpkin Cotyledons by CPTA. A Pigment and Ultrastructual Study

1974 ◽  
Vol 1 (1) ◽  
pp. 119 ◽  
Author(s):  
DJ Simpson ◽  
CO Chichester ◽  
TH Lee
Keyword(s):  
Light Intensity ◽  
Chlorophyll Biosynthesis ◽  
Carotenoid Biosynthesis ◽  
Chlorophyll Synthesis ◽  
High Light Intensity ◽  
High Light ◽  
Trimethylammonium Chloride ◽  
Plastid Development ◽  
Plastid Ultrastructure ◽  
Chlorophyll Accumulation

The effects of 2-(4-chlorophenylthio)ethyldiethylammonium chloride (CPTA) on chlorophyll accumulation, carotenoid biosynthesis and plastid ultrastructure were examined in expanding excised pumpkin cotyledons. CPTA in the dark caused an increased synthesis of non-photoconvertible protochlorophyll but had no effect on the ultrastructure of the starch-containing plastids. In the light, CPTA was a powerful inhibitor of chlorophyll synthesis in greening cotyledons, especially at high light intensity, and induced the accumulation of lycopene. When applied to the greened cotyledons, CPTA caused the transformation of the chloroplasts to chromoplast-like organelles containing osmiophilic globules and lycopene crystalloids. Two other structurally similar compounds,diethyl[4-{3'-(4"-methylphenyl)-3-oxoprop-2' -enyl}phenoxyethyl]ammonium chloride (SK&F 13831) and (2-chloroethyl)trimethylammonium chloride (chlormequat), also caused lycopene accumulation and inhibited chlorophyll synthesis. It is possible that CPTA can induce the formation of chromoplasts from proplastids and chloroplasts in tissue that does not normally contain such organelles.

Sebaceous Basal Cell Carcinoma - An Ultrastructural Study

1982 ◽  
Vol 40 ◽  
pp. 232-233
Author(s):  
Annette M. Andrews ◽  
Boon-Nam Blackwell ◽  
Terrell R. Hoage ◽  
Fred F. Kadiubar
Keyword(s):  
Basal Cell Carcinoma ◽  
Cell Carcinoma ◽  
Basal Cell ◽  
Sebaceous Gland ◽  
Osmium Tetroxide ◽  
Wistar Rat ◽  
Uranyl Acetate ◽  
Lead Citrate ◽  
Tumor Specimen ◽  
Standard Procedures

Basal cell carcinoma with sebaceous gland differentiation has been described in mice and humans but spontaneous skin tumors of this type are uncommon in the rat.The tumor specimen was taken from a 26 month old male Wistar rat. Electron microscopy specimens were fixed by immersion in cacodylatebuffered 4% glutaraldehyde, post-fixed in 1% osmium tetroxide, dehydrated, cleared and embedded by standard procedures. Semi-thin (μm) sections were stained with ethanolic uranyl acetate followed by lead citrate, then examined on a Philips EM201 electron microscope.

Bundle sheath cells and cell-specific plastid development in Arabidopsis leaves

Development ◽  
1998 ◽  
Vol 125 (10) ◽  
pp. 1815-1822 ◽  
Author(s):  
E.A. Kinsman ◽  
K.A. Pyke
Keyword(s):  
Vascular Tissue ◽  
Chloroplast Development ◽  
Mesophyll Cell ◽  
Ultrastructural Level ◽  
Bundle Sheath ◽  
Plastid Development ◽  
Mesophyll Cells ◽  
Differential Development ◽  
Bundle Sheath Cells ◽  
Sheath Cells

Bundle sheath cells form a sheath around the entire vascular tissue in Arabidopsis leaves and constitute a distinct leaf cell type, as defined by their elongate morphology, their position adjacent to the vein and by differences in their chloroplast development compared to mesophyll cells. They constitute about 15% of chloroplast-containing cells in the leaf. In order to identify genes which play a role in the differential development of bundle sheath and mesophyll cell chloroplasts, a screen of reticulate leaf mutants of Arabidopsis was used to identify a new class of mutants termed dov (differential development of vascular-associated cells). The dov1 mutant clearly demonstrates a cell-specific difference in chloroplast development. Mutant leaves are highly reticulate with a green vascular pattern. The underlying bundle sheath cells always contain normal chloroplasts, whereas chloroplasts in mesophyll cells are abnormal, reduced in number per cell and seriously perturbed in morphology at the ultrastructural level. This demonstrates that differential chloroplast development occurs between the bundle sheath and mesophyll cells in the Arabidopsis leaf.

scholarly journals THE FINE STRUCTURE OF CHLOROPLAST STROMA FOLLOWING ALDEHYDE OSMIUM-TETROXIDE FIXATION

1965 ◽  
Vol 24 (1) ◽  
pp. 79-93 ◽  
Author(s):  
B. E. S. Gunning
Keyword(s):  
Avena Sativa ◽  
Osmium Tetroxide ◽  
Ground Substance ◽  
Plastid Development ◽  
Rapid Synthesis ◽  
Thin Sections ◽  
Green Algal ◽  
Leaf Tissues ◽  
Chloroplast Stroma ◽  
Cytoplasmic Ribosomes

Markedly improved fixation of leaf tissues is obtained by means of a glutaraldehyde (or acrolein)-osmium tetroxide procedure, as compared with the results of potassium permanganate or osmium tetroxide fixation methods. The procedure has proved useful in all species so far examined. Chloroplasts are particularly well preserved. In this paper details of components of the ground-substance of Avena sativa plastids are presented. They include the following:—(i) The "tromacentre" is an area of aggregated fibrils, each 85 A in diameter, and of uncertain length. Individual fibrils may be composed of subunits. The whole aggregate is usually up to 1 µ in diameter, and is visible in thin sections in the light microcope. It is present at all stages of plastid development, and, under conditions of rapid synthesis in the plastid, it may be up to 2 µ in diameter. Evidence that it is proteinaceous is presented. Osmiophilic globules are often associated with it. (ii) Areas which resemble bacterial and blue-green algal nucleoplasms, containing fibrils approximately 30 A wide. These regions are smaller than the stromacentre and, like that structure, they occur in all stages of plastid development. Unlike it, there are several such areas per chloroplast. (iii) Particles which have some of the morphological and staining characteristics of ribosomes. Present at all stages of development, they are approximately two-thirds the size of the cytoplasmic ribosomes. They can occur in groups, thus resembling polyribosomes. (iv) The remaining material is granular, and may include dissociated portions of stromacentre material. The validity of the observations and their significance is discussed.

scholarly journals Developmental Effects on Relative Use of PEPCK and NADP-ME Pathways of C4 Photosynthesis in Maize

2021 ◽  
Author(s):  
Jennifer J Arp ◽  
Shrikaar Kambhampati ◽  
Kevin Chu ◽  
Somnath Koley ◽  
Lauren M Jenkins ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Leaf Development ◽  
Phosphoenolpyruvate Carboxykinase ◽  
C4 Photosynthesis ◽  
Leaf Age ◽  
Bundle Sheath ◽  
Decarboxylase Activity ◽  
Mesophyll Cells ◽  
Source To Sink ◽  
Canopy Position

C4 photosynthesis is an adaptive photosynthetic pathway which concentrates CO2 around Rubisco in specialized bundle sheath cells to reduce photorespiration. Historically, the pathway has been characterized into three different subtypes based on the decarboxylase involved, although recent work has provided evidence that some plants can use multiple decarboxylases, with maize in particular using both the NADP-malic enzyme (NADP-ME) pathway and phosphoenolpyruvate carboxykinase (PEPCK) pathway. Parallel C4 pathways could be advantageous in balancing energy and reducing equivalents between bundle sheath and mesophyll cells, in decreasing the size of the metabolite gradients between cells and may better accommodate changing environmental conditions or source to sink demands on growth. The enzyme activity of C4 decarboxylases can fluctuate with different stages of leaf development, but it remains unclear if the pathway flexibility is an innate aspect of leaf development or an adaptation to the leaf microenvironment that is regulated by the plant. In this study, variation in the two C4 pathways in maize were characterized at nine plant ages throughout the life cycle. Two positions in the canopy were examined for variation in physiology, gene expression, metabolite concentration, and enzyme activity, with particular interest in asparagine as a potential regulator of C4 decarboxylase activity. Variation in C4 and C3 metabolism was observed for both leaf age and canopy position, reflecting the ability of C4 pathways to adapt to changing microenvironments.

An SEM/TEM study of structures associated with bacteroids in peanut (Arachis hyppogaea L.) root nodules

1988 ◽  
Vol 46 ◽  
pp. 288-289
Author(s):  
C. J. Emerson ◽  
A. K. Bal
Keyword(s):  
Arachis Hypogaea ◽  
Acetylene Reduction ◽  
Phosphate Buffer ◽  
Osmium Tetroxide ◽  
Root Nodules ◽  
Acetylene Reduction Activity ◽  
Reduction Activity ◽  
Dense Bodies ◽  
Growth Chambers ◽  
Large Spherical

Nitrogen-fixing peanut root nodules have highly specialized, large spherical bacteroids and show higher acetylene-reduction activity than the nodules of other legumes induced by the same strain of rhizobia. Differences are also found in their anatomical organization and with regard to bacteroid-associated organelles and other structures (dense bodies) found on the host-symbiont interface. In this investigation, further description of these organelles and structures was made at different stages of development in a correlated SEM/TEM study.Arachis hypogaea L. cv. Jumbo Virginia plants were grown in environmental growth chambers and inoculated with Rhizobium sp. 32Hl. For TEM, slices of nodules were fixed in Karnovsky's fixative in Sorensen's phosphate buffer, pH 7.2 for 1 h at 4°C. Tissues were rinsed in buffer, post-fixed with 1% phosphate-buffered osmium tetroxide for 1 h at 4°C and dehydrated in ethanol. 1% p-phenylenediamine was added at the 70% ethanol step (30 min) to preserve lipids.

Changes in the plastid ultrastructure during greening in cultured soybean cells

1989 ◽  
Vol 47 ◽  
pp. 1010-1011
Author(s):  
M.A. Gillott ◽  
G. Erdös ◽  
D. E. Buetow
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Gene Regulation ◽  
Uranyl Acetate ◽  
Total Darkness ◽  
Ultrastructural Changes ◽  
Ethanol Dehydration ◽  
Mesophyll Cells ◽  
Plastid Ultrastructure ◽  
Transmission Electron

Mesophyll cells isolated from soybeans (Glycine max, L. Merr. var. Corsoy) can be grown photoautotrophically in suspension culture. The SB-P cell line can be bleached by maintaining them in total darkness in sucrose supplemented media for several weeks, and will regain photosynthetic competency when returned to the light. This system is ideally suited for the study of gene regulation and the biochemical and ultrastructural changes which occur during the greening process.Cells were fixed for electron microscopy after 8 weeks of growth in total darkness and at intervals of 1 h to 12 d after transfer to the light. Chlorophyll measurements were determined for each sample. For transmission electron microscopy, the cells were fixed for 1-2 h in 4% glutaraldehyde in 0.1M Pipes buffer, pH 7.4, washed in the same buffer, then postfixed for 1 h in 1% OsO4 in Pipes, pH 6.8. Following a graded ethanol dehydration series the cells were transferred into propylene oxide and embedded in Epon. Sections were stained with uranyl acetate and observed on a JEOL 100C TEM operated at 80 kV.

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