Ripening-Associated Microstructural Changes in Antisense ACC Synthase Tomato Fruit

2001 ◽  
Vol 7 (1) ◽  
pp. 59-71 ◽  
Author(s):  
G. O. Sozzi ◽  
A. A. Fraschina ◽  
M. A. Castro
Keyword(s):  
Cell Wall ◽  
Tomato Fruit ◽  
Environmental Scanning Electron Microscopy ◽  
Middle Lamella ◽  
Acc Synthase ◽  
Ethylene Biosynthesis ◽  
Environmental Scanning ◽  
High Electron ◽  
Exogenous Ethylene ◽  
Transgenic Tomatoes

The ultrastructural impact of low ethylene biosynthesis (less than 0.5% of normal levels) was evaluated in transgenic (A11.1) tomatoes ( Lycopersicon esculentumMill.) expressing an antisense 1-aminocyclopropane-1-carboxylic acid synthase (ACC-S) transgene by means of transmission and environmental scanning electron microscopy. In 48-day mature green fruit, no significant ultrastructural differences were found between transgenic and control tomatoes. In 78-day control fruit, which were overripe and showed deteriorated texture, many areas of the cytoplasm were devoid of structures, and micrographs showed cell collapse with folding and dissolution of the cell wall. On the other hand, in 90-day transgenic fruit, which were firm and not ripe, the cytoplasm showed a relatively high electron density. Plastids retained remnants of chloroplast thylakoids along with significant amounts of osmiophylic plastoglobuli, but lycopene was not detected. Conspicuous starch granules were observed in mature green transgenic tomatoes, but were not detected in 90-day chlorochromoplasts. Electron-dense regions reflecting the integrity of the middle lamella alternated with other partially degraded regions. This incipient dissolution of the middle lamella pectic polymers may be attributable to nonenzymatic deaggregation or to cell-wall hydrolases which could be ethylene independent or responsive to very low levels of ethylene. Besides, cells were attached along extended contact areas and appeared turgid. This feature may provide an explanation of firmness retention that does not solely involve cell walls. Disruption of the middle lamella and development of lycopene crystalloids were observed when exogenous ethylene (12 ppm) was applied.

scholarly journals Properties of chemically and mechanically isolated fibres of spruce (Picea abies [L.] Karst.). Part 1: Structural and chemical characterisation

Holzforschung ◽  
2005 ◽  
Vol 59 (2) ◽  
pp. 240-246 ◽  
Author(s):  
Ingo Burgert ◽  
Notburga Gierlinger ◽  
Tanja Zimmermann
Keyword(s):  
Cell Wall ◽  
Picea Abies ◽  
Environmental Scanning Electron Microscopy ◽  
Middle Lamella ◽  
Solid Wood ◽  
Wall Structure ◽  
Environmental Scanning ◽  
Cell Wall Assembly ◽  
Ir Microscopy ◽  
Mechanical Isolation

Abstract Single fibres of spruce (Picea abies [L.] Karst.) were isolated both chemically and mechanically from a solid wood sample. Mechanical isolation was carried out using very fine tweezers to peel out fibres, thereby taking advantage of the low shear strength between them. Chemical isolation was achieved using hydrogen peroxide and glacial acetic acid. Fibres were examined with Fourier-transform infrared (FT-IR) microscopy, and field-emission environmental scanning electron microscopy (FE-ESEM) in low-Vacuum mode to compare the isolation techniques with respect to their influence on cell wall structure and polymer assembly. The chemical treatment led to degradation of lignin and hemicelluloses, significantly influencing the cell wall assembly and structure. The cell wall polymers of mechanically isolated fibres remained in their natural constitution. As expected, the peeling process caused separation of cell wall layers. Our examinations indicate that delamination predominately took place at the interface between the secondary cell wall and the compound middle lamella. However, fracture between the S1 and S2 layers was examined as well. With respect to fibre quality, it was of particular importance that transverse crack propagation in the secondary cell walls (S2) was not observed.

Galactosidases in tomato fruit ontogeny: decreased galactosidase activities in antisense ACC synthase fruit during ripening and reversal with exogenous ethylene

1998 ◽  
Vol 25 (2) ◽  
pp. 237 ◽  
Author(s):  
G.O. Sozzi ◽  
S.A. Camperi ◽  
O. Cascone ◽  
A.A. Fraschina
Keyword(s):  
De Novo ◽  
Tomato Fruit ◽  
Acc Synthase ◽  
Green Fruit ◽  
Chlorophyll Breakdown ◽  
Level Of Activity ◽  
Promotive Effect ◽  
Ripe Stage ◽  
Exogenous Ethylene ◽  
Transgenic Tomatoes

α- and β-galactosidase (α- and β-Gal) activities, firmness and pigment content were analysed in tomato (Lycopersicon esculentum Mill.) pericarp during fruit growth and ripening, comparing normal fruit with transgenic fruit containing an ACC-synthase antisense transgene. Normal and transgenic immature green fruit had similar temporal patterns of total α- and β-Gal activity. Immature 21-day-old fruit displayed 93% and 134% higher α- and β-Gal activity on a per gram fresh weight basis, respectively, than mature-green fruit. During ripening, normal fruit presented increasing levels of α- and β-Gal activity towards the red-ripe stage. β-Gal II was detected in mature-green tomatoes; it rose rapidly and reached maximum values at the red-ripe stage. In contrast, α- and β-Gal activity in antisense fruit decreased after reaching the breaker stage, and a low continuous level of activity was apparent between 54 and 108 days after anthesis. 48- to 108-day-old transgenic fruit showed constant basal levels of β-Gal II. There were no significant differences in enzyme activity between antisense attached and detached fruit. An exogenous ethylene treatment performed in transgenic tomatoes brought about a promotive effect on total α- and β-Gal activity in general and on β-Gal II in particular, thus suggesting a role for ethylene in de novo synthesis or activation of these enzymes. Softening, chlorophyll breakdown and lycopene biosynthesis were impaired in the antisense fruits, but the impairment was only complete for lycopene synthesis and all were reversed by applied ethylene. These results can be associated with the signal transduction pathways proposed to be operational during tomato ripening.

Effects of Exogenous Ethylene on AC and Rin Tomato Fruit

2014 ◽  
Vol 1033-1034 ◽  
pp. 677-680
Author(s):  
Ling Li ◽  
Hai Xue Liu ◽  
Yong Bo Peng ◽  
Shi Li ◽  
Tie Ling Liu
Keyword(s):  
Respiration Rate ◽  
Ethylene Production ◽  
Tomato Fruit ◽  
Acc Oxidase ◽  
Acc Synthase ◽  
Ethylene Biosynthesis ◽  
Flesh Firmness ◽  
Ethephon Treatment ◽  
Production Increase ◽  
Exogenous Ethylene

The flesh firmness of AC andrinmutant tomato fruits picked freshly were the largest. Respiration rate and ethylene production were very low at this time. With ethylene production increase, fruit firmness began to decline. 100μL/L ethephon significantly increased AC tomato fruit ethylene release, respiration rate, ACS activity and ACO activity, and decreased flesh firmness. However, there were no significant differences inrinmutant between control and ethephon treatment. It was shown RIN transcription factor regulated ethylene biosynthesis by ACC synthase and ACC oxidase.

Acetyl Group Distribution in Acetylated Wood Investigated by Microautoradiography

Holzforschung ◽  
2001 ◽  
Vol 55 (3) ◽  
pp. 270-275 ◽  
Author(s):  
Marie Rosenqvist
Keyword(s):  
Cell Wall ◽  
Weight Gain ◽  
Acetic Anhydride ◽  
Wood Cell Wall ◽  
Environmental Scanning Electron Microscopy ◽  
Environmental Scanning ◽  
Accurate Information ◽  
Concentration Gradients ◽  
Good Opportunity ◽  
Acetyl Group

Summary Sapwood of Scots pine (Pinus silvestris L.) was acetylated with 14C- and 3H-labelled acetic anhydride. The distribution of acetyl groups was investigated with microautoradiography and microautoradiographs were evaluated with ESEM, Environmental Scanning Electron Microscopy. The investigation showed that the impregnation of wood with radioisotope-labelled substances provides a good opportunity to investigate the location of substances covalently bonded to the wood material. Introduced 14C-labelled acetyl groups show an even distribution in the wood cell wall, with no discernible concentration gradients at acetylation levels of about 5, 15 and 20% weight gain. 3H-labelled acetyl groups show an even distribution in the wood cell wall at 15 and 20% weight gain, with no discernible concentration gradients. At the 5% weight gain level, however, an uneven distribution of 3H-labelled acetyl groups over the cell wall is observed. Nevertheless, the unevenness is random and no concentration gradient is discernible at this level. 3H with a relatively high resolution, 0.5–1 μm, compared to 14C with a resolution of 2–5 μm, gives more accurate information about where exactly the acetyl groups are situated in the wood cell wall. Acetic anhydride was evenly distributed when a full impregnation procedure was used. The chemical and physical properties of acetic anhydride allow a uniform penetration into the pine cell wall and a complete acetylation takes place when the specimens are heated.

Role of Ethylene in the Biosynthesis of Fatty Acid-Derived Volatiles in Tomato Fruits

2011 ◽  
Vol 343-344 ◽  
pp. 937-950
Author(s):  
Yuan Hong Xie ◽  
Hong Yan Gao ◽  
Yun Bo Luo ◽  
Hong Xing Zhang ◽  
Xiang Ning Chen ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Linolenic Acid ◽  
Tomato Fruit ◽  
Ethylene Biosynthesis ◽  
Hydroperoxide Lyase ◽  
Wild Type ◽  
Tomato Fruits ◽  
Aroma Volatiles ◽  
Exogenous Ethylene

Regulation of ethylene biosynthesis or action has an important effect on volatiles production in tomato (Lycopersicon esculentum) fruits. To understand the role of ethylene in the biosynthesis of fatty acid-derived aroma volatiles in tomato, we used Lichun tomato from a transgenic line with strictly suppression of ethylene biosynthesis (antisenseLeACS2tomato) and its wild type background line. This study was focused on the levels of the precursor substrates, activities and transcriptional levels of aroma volatile-related enzymes, including lipoxygenase (LOX), hydroperoxide lyase (HPL) and alcohol dehydrogenase (ADH). We also investigated the different abilities of converting the precursor substrates to aroma volatiles in ethylene suppressed transgenic and wild-type (WT) tomato fruits. Our results showed that the contents of endogenous linoleic and linolenic acid in tomato fruits were ethylene depended. Suppression of ethylene biosynthesis increased the content of endogenous linolenic acid inLichuntomato fruit and then declined the ratio of linoleic /linolenic acid. Exogenous ethylene changed the value of linoleic acid /linolenic acid in antisenseLeACS2(ACS) tomato fruit to the similar level of WT. During the ripening of wild type Lichun tomato fruit, LOX activity was ethylene and development dependent. Suppression of ethylene biosynthesis did not inhibit the transcriptional expression ofLoxCgene. And the HPL and ADH activities were partial ethylene-dependent during the ripening of wild typeLichuntomato fruit. Moreover, suppression of ethylene biosynthesis also affected the bioconversion of unsaturated-fatty acid precursors to C6 aldehydes and C6 alcohols. All these results indicated that ethylene had complicated effects on the biosynthesis of fatty acid-derived armoa volatiles by affecting the precursor’s content, enzyme activities, enzyme expression and the substrate utilization.

scholarly journals Inhibition of Ethylene Biosynthesis and Action in Cut Carnations (Dianthus caryophyllus L.) by Aminotriazole

1994 ◽  
Vol 119 (2) ◽  
pp. 282-287 ◽  
Author(s):  
Steven A. Altman ◽  
Theophanes Solomos
Keyword(s):  
Morphological Changes ◽  
Dianthus Caryophyllus ◽  
Acc Synthase ◽  
Ethylene Biosynthesis ◽  
Vase Life ◽  
Ethylene Evolution ◽  
Dependent Inhibition ◽  
Ethylene Action ◽  
Exogenous Ethylene ◽  
Acc Content

Treating `Elliott's White' cut carnations with 50 or 100 mm aminotriazole for 4 days inhibits the respiratory climacteric and significantly extends vase life. Aminotriazole induced time- and concentration-dependent inhibition of ethylene evolution and onset of the ethylene climacteric by inhibiting ACC synthase activity. Flowers treated with 50 or 100 mm aminotriazole for 2 days exhibited concentration-dependent increases in ethylene evolution, respiratory activity, ACC synthase activity, and petal ACC content in response to the application of exogenous ethylene at 10 μl·liter-1. Senescence-associated morphological changes, increased ACC synthase activity, ACC content, and ethylene evolution were completely inhibited in flowers treated for 4 days with 100 mm aminotriazole. Although treatment with 50 mm aminotriazole for 4 days did not completely inhibit components of the ethylene biosynthetic pathway, no morphological or respiratory responses to the application of exogenous ethylene at 10 μl·liter-1 were observed, a result indicating that prolonged aminotriazole treatment inhibited ethylene action. Chemical names used: 3-1H-amino-1,2,4-triazole-1-yl (aminotriazole), 1-aminocyclopropane-1-carboxylic acid (ACC).

Nitrate increases ethylene production and aerenchyma formation in roots of lowland rice plants under water stress

2017 ◽  
Vol 44 (4) ◽  
pp. 430 ◽  
Author(s):  
Cuimin Gao ◽  
Lei Ding ◽  
Yingrui Li ◽  
Yupei Chen ◽  
Jingwen Zhu ◽  
...  
Keyword(s):  
Water Stress ◽  
Ethylene Production ◽  
Oryza Sativa L ◽  
Acc Synthase ◽  
Ethylene Biosynthesis ◽  
Lowland Rice ◽  
Shoot Biomass ◽  
Aerenchyma Formation ◽  
Exogenous Ethylene ◽  
Root Cortical Aerenchyma

Ethylene increases root cortical aerenchyma formation in maize (Zea mays L.), rice (Oryza sativa L.) and other species. To further investigate the effects of nitrate, ammonium and water stress on ethylene production and aerenchyma formation in roots, two lowland rice cultivars (Shanyou 63, hybrid indica, and Yangdao 6, inbred indica) were cultured hydroponically with 10% (w/v) polyethylene glycol to simulate water stress. Water stress decreased shoot biomass, stomatal conductivity and leaf water potential in cultivars fed with nitrate but not with ammonium. Water stress induced more aerenchyma formation in cultivars fed with nitrate rather than ammonium, and increased cortical aerenchyma was found in Yangdao 6. Endogenous ethylene production by roots increased significantly under water stress in plants fed with nitrate rather than ammonium. Exogenous ethylene stimulated root cortical aerenchyma formation. Expression of the ethylene biosynthesis gene 1-aminocyclo-propane-1-carboxylic acid (ACC) synthase (ACS5) was greater in roots fed with nitrate rather than ammonium in the presence and absence of water stress. The expression of ethylene signalling pathway genes involved in programmed cell death (lesion-simulating disease (L.S.D.)1.1 and L.S.D.2; enhanced disease susceptibility (EDS) and phytoalexin-deficient (PAD4)) were regulated by the N form and water stress. In plants of cultivars fed with ammonium, L.S.D.1.1 expression increased under water stress, whereas L.S.D.2, EDS and PAD4 expression decreased. In conclusion, nitrate increases ethylene production and cortical aerenchyma formation in roots of water-stressed lowland rice. However, ammonium increased L.S.D.1.1 expression in water-stressed roots, and decreased ACS5, EDS and PAD4 expression, which would inhibit ethylene production and aerenchyma formation.

Environmental scanning electron microscopy of fresh human gallstones reveals new morphologies of precipitated calcium salts

1992 ◽  
Vol 50 (2) ◽  
pp. 1322-1323
Author(s):  
Howard S. Kaufman ◽  
Keith D. Lillemoe ◽  
John T. Mastovich ◽  
Henry A. Pitt
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Environmental Scanning Electron Microscopy ◽  
Environmental Scanning ◽  
X Ray Diffraction ◽  
Calcium Salts ◽  
Cholesterol Gallstones ◽  
X Ray ◽  
Ca Carbonate ◽  
Scanning Electron

Gallstones contain precipitated cholesterol, calcium salts, and proteins. Calcium (Ca) bilirubinate, palmitate, phosphate, and carbonate occurring in gallstones have variable morphologies but characteristic windowless energy dispersive x-ray (EDX) spectra. Previous studies of gallstone microstructure and composition using scanning electron microscopy (SEM) with EDX have been limited to dehydrated samples. In this state, Ca bilirubinates appear as either glassy masses, which predominate in black pigment stones, or as clusters, which are found mostly in cholesterol gallstones. The three polymorphs of Ca carbonate, calcite, vaterite, and aragonite, have been identified in gallstones by x-ray diffraction, however; the morphologies of these crystals vary in the literature. The purpose of this experiment was to study fresh gallstones by environmental SEM (ESEM) to determine if dehydration affects gallstone Ca salt morphology.Gallstones and bile were obtained fresh at cholecystectomy from 6 patients. To prevent dehydration, stones were stored in bile at 37°C. All samples were studied within 4 days of procurement.

Detector strategies for environmental scanning electron microscopy

1992 ◽  
Vol 50 (2) ◽  
pp. 1296-1297
Author(s):  
Klaus-Ruediger Peters
Keyword(s):  
High Vacuum ◽  
Environmental Scanning Electron Microscopy ◽  
Charge Carriers ◽  
Environmental Scanning ◽  
Surface Information ◽  
X Ray ◽  
Detector Electrode ◽  
Electrons And Ions ◽  
Low Energy Electrons ◽  
Environmental Sem

Environmental SEM operate at specimen chamber pressures of ∼20 torr (2.7 kPa) allowing stabilization of liquid water at room temperature, working on rugged insulators, and generation of an environmental secondary electron (ESE) signal. All signals available in conventional high vacuum instruments are also utilized in the environmental SEM, including BSE, SE, absorbed current, CL, and X-ray. In addition, the ESEM allows utilization of the flux of charge carriers as information, providing exciting new signal modes not available to BSE imaging or to conventional high vacuum SEM.In the ESEM, at low vacuum, SE electrons are collected with a “gaseous detector”. This detector collects low energy electrons (and ions) with biased wires or plates similar to those used in early high vacuum SEM for SE detection. The detector electrode can be integrated into the first PLA or positioned at any other place resulting in a versatile system that provides a variety of surface information.

Silicification of wood-cell walls

1994 ◽  
Vol 52 ◽  
pp. 428-429
Author(s):  
S. E. Keckler ◽  
D. M. Dabbs ◽  
N. Yao ◽  
I. A. Aksay
Keyword(s):  
Electron Microscopy ◽  
Cell Wall ◽  
Cell Walls ◽  
Lignin Content ◽  
Resin Composite ◽  
Middle Lamella ◽  
Cellulose Fibers ◽  
Complex Structures ◽  
Rich Region ◽  
Inorganic Precursors

Cellular organic structures such as wood can be used as scaffolds for the synthesis of complex structures of organic/ceramic nanocomposites. The wood cell is a fiber-reinforced resin composite of cellulose fibers in a lignin matrix. A single cell wall, containing several layers of different fiber orientations and lignin content, is separated from its neighboring wall by the middle lamella, a lignin-rich region. In order to achieve total mineralization, deposition on and in the cell wall must be achieved. Geological fossilization of wood occurs as permineralization (filling the void spaces with mineral) and petrifaction (mineralizing the cell wall as the organic component decays) through infiltration of wood with inorganics after growth. Conversely, living plants can incorporate inorganics into their cells and in some cases into the cell walls during growth. In a recent study, we mimicked geological fossilization by infiltrating inorganic precursors into wood cells in order to enhance the properties of wood. In the current work, we use electron microscopy to examine the structure of silica formed in the cell walls after infiltration of tetraethoxysilane (TEOS).

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