Deactivation of aquaporins decreases internal conductance to CO2 diffusion in tobacco leaves grown under long-term drought

2008 ◽  
Vol 35 (7) ◽  
pp. 553 ◽  
Author(s):  
Shin-Ichi Miyazawa ◽  
Satomi Yoshimura ◽  
Yuki Shinzaki ◽  
Masayoshi Maeshima ◽  
Chikahiro Miyake
Keyword(s):  
Water Permeability ◽  
Abaxial Epidermis ◽  
Tobacco Leaves ◽  
Surface Areas ◽  
Co2 Diffusion ◽  
Internal Conductance ◽  
Air Space ◽  
Leaf Tissues ◽  
Intercellular Air Space

We compared the diffusion conductance to CO2 from the intercellular air space to the chloroplasts (internal conductance (g i)) between tobacco leaves acclimated to long-term drought (drought-acclimated (DA)) and those grown under sufficient irrigation (well-watered (WW)), and analysed the changes in g i in relation to the leaf anatomical characteristics and a possible CO2 transporter, aquaporin. The g i, which was estimated by combined analyses of CO2 gas exchange with chlorophyll fluorescence, in the DA plants was approximately half of that in the WW plants. The mesophyll and chloroplast surface areas exposing the intercellular air space, which potentially affect g i, were not significantly different between the WW and DA plants. The amounts of plasma membrane aquaporins (PIP), immunochemically determined using radish PIP antibodies, were unrelated to g i. After treatment with HgCl2, an aquaporin inhibitor, the water permeability of the leaf tissues (measured as the weight loss of fully-turgid leaf disks without the abaxial epidermis in 1 m sorbitol) in WW plants decreased with an increase in HgCl2 concentration. The g i in the WW plants decreased to similar levels to the DA plants when the detached leaflets were fed with 0.5 mm HgCl2. In contrast, both water permeability and g i were insensitive to HgCl2 treatments in DA plants. These results suggest that deactivation of aquaporins is responsible for the significant reduction in g i observed in plants growing under long-term drought.

scholarly journals Induction of cell wall phenolic monomers as part of direct defense response in maize to pink stem borer (Sesamia inferens Walker) and non-insect interactions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
P. Lakshmi Soujanya ◽  
J. C. Sekhar ◽  
C. V. Ratnavathi ◽  
Chikkappa G. Karjagi ◽  
E. Shobha ◽  
...  
Keyword(s):  
Induced Defense ◽  
Stem Borer ◽  
Defense Responses ◽  
Short Term ◽  
Mechanical Wounding ◽  
Leaf Tissues ◽  
Short And Long Term ◽  
Insect Interactions ◽  
Induced Defense Responses

AbstractPink stem borer (PSB) causes considerable yield losses to maize. Plant–insect interactions have significant implications for sustainable pest management. The present study demonstrated that PSB feeding, mechanical wounding, a combination of mechanical wounding and PSB regurgitation and exogenous application of methyl jasmonate have induced phenolic compound mediated defense responses both at short term (within 2 days of treatment) and long term (in 15 days of treatment) in leaf and stalk tissues of maize. The quantification of two major defense related phenolic compounds namely p-Coumaric acid (p-CA) and ferulic acid (FA) was carried out through ultra-fast liquid chromatography (UFLC) at 2 and 15 days after imposing the above treatments. The p-CA content induced in leaf tissues of maize genotypes were intrinsically higher when challenged by PSB attack at V3 and V6 stages in short- and long-term responses. Higher p-CA content was observed in stalk tissues upon wounding and regurgitation in short- and long-term responses at V3 and V6 stages. Significant accumulation of FA content was also observed in leaf tissues in response to PSB feeding at V3 stage in long-term response while at V6 stage it was observed both in short- and long-term responses. In stalk tissues, methyl jasmonate induced higher FA content in short-term response at V3 stage. However, at V6 stage PSB feeding induced FA accumulation in the short-term while, wounding and regurgitation treatment-induced defense responses in the long-term. In general, the resistant (DMRE 63, CM 500) and moderately resistant genotypes (WNZ ExoticPool) accumulated significantly higher contents of p-CA and FA content than susceptible ones (CM 202, BML 6) in most of the cases. The study indicates that phenolic mediated defense responses in maize are induced by PSB attack followed by wounding and regurgitation compared to the other induced treatments. Furthermore, the study confirmed that induced defense responses vary with plant genotype, stage of crop growth, plant tissue and short and long-term responses. The results of the study suggested that the Phenolic acids i.e. p-CA and FA may contribute to maize resistance mechanisms in the maize-PSB interaction system.

scholarly journals Leaf proteome modulation and cytological features of seagrass Cymodocea nodosa in response to long-term high CO2 exposure in volcanic vents

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Amalia Piro ◽  
Letizia Bernardo ◽  
Ilia Anna Serra ◽  
Isabel Barrote ◽  
Irene Olivé ◽  
...  
Keyword(s):  
Metabolic Pathways ◽  
Total Protein Content ◽  
Cymodocea Nodosa ◽  
Cell Respiration ◽  
Strong Reduction ◽  
Vulcano Island ◽  
Leaf Tissues ◽  
Cytological Features ◽  
Harvesting Process

AbstractSeagrass Cymodocea nodosa was sampled off the Vulcano island, in the vicinity of a submarine volcanic vent. Leaf samples were collected from plants growing in a naturally acidified site, influenced by the long-term exposure to high CO2 emissions, and compared with others collected in a nearby meadow living at normal pCO2 conditions. The differential accumulated proteins in leaves growing in the two contrasting pCO2 environments was investigated. Acidified leaf tissues had less total protein content and the semi-quantitative proteomic comparison revealed a strong general depletion of proteins belonging to the carbon metabolism and protein metabolism. A very large accumulation of proteins related to the cell respiration and to light harvesting process was found in acidified leaves in comparison with those growing in the normal pCO2 site. The metabolic pathways linked to cytoskeleton turnover also seemed affected by the acidified condition, since a strong reduction in the concentration of cytoskeleton structural proteins was found in comparison with the normal pCO2 leaves. Results coming from the comparative proteomics were validated by the histological and cytological measurements, suggesting that the long lasting exposure and acclimation of C. nodosa to the vents involved phenotypic adjustments that can offer physiological and structural tools to survive the suboptimal conditions at the vents vicinity.

Long-Term Release from High Level Waste Glass - Part IV: The Effect of Leaching Mechanism

1984 ◽  
Vol 44 ◽  
Author(s):  
Eberhard Freude ◽  
Bernd Grambow ◽  
Werner Lutze ◽  
Harald Rabe ◽  
Rodney C. Ewing
Keyword(s):  
Linear Time ◽  
High Surface ◽  
High Level Waste ◽  
Corrosion Mechanism ◽  
Surface Areas ◽  
One Year ◽  
The Stability ◽  
High Level ◽  
Long Term Behavior

During the past ten years extensive data have been determined for the corrosion of nuclear waste forms in short-term laboratory experiments (usually less than one year). The long-term behavior of glass has been inferred by: (1) the acceleration of corrosion rates at high temperatures [1]; (2) the use of high surface areas of the glass to small volumes of solution [1]; and the analysis of natural glasses altered over long periods of geologic time [2, 3]. The most recent efforts have concentrated on understanding the mechanisms of corrosion [1, 4, 5]. The corrosion mechanism may be used to make long-term extrapolations of the “stability” of the waste form. In this paper, we consider a linear time dependence for the corrosion under near saturation conditions and use a rate equation in the QTERM code [6, 7, 8] to model the long-term behavior of the German glass, C-31−3EC [9], JSS A [10, 11] and SRL TDS 131 [1]. The data base for C-31−3EC has been published elsewhere [9, 12, 13, 14], and we include experimental work completed by Rabe for boron and silica, at 200°C.

Is a Low Internal Conductance to CO2 Diffusion a Consequence of Succulence in Plants with Crassulacean Acid Metabolism?

1997 ◽  
Vol 24 (6) ◽  
pp. 777 ◽  
Author(s):  
Kate Maxwell ◽  
Susanne von Caemmerer ◽  
John R. Evans
Keyword(s):  
Crassulacean Acid Metabolism ◽  
Acid Metabolism ◽  
Ambient Air ◽  
Co2 Assimilation ◽  
Co2 Partial Pressure ◽  
Co2 Diffusion ◽  
Internal Conductance ◽  
C3 Species ◽  
Cam Species ◽  
Transient Phases

Leaf internal conductance to CO2 (gi) from substomatal cavity to the carboxylation sites of Rubisco was measured in the leaf succulent CAM species, Kalanchoe daigremontiana Hamet et Perr. Measurements were made during Rubisco-mediated atmospheric C3 carboxylation in phase IV photosynthesis. Using simultaneous gas exchange and chlorophyll fluorescence techniques, internal conductance was calculated to be 0.05 mol m-2 s-1 bar-1 , when measured at both saturating and limiting light. This is one of the lowest recorded values for gi as compared to a range of C3 species with comparable Rubisco content and indicates a large diffusion limitation to atmospheric CO2 fixation through the C3 pathway in K. daigremontiana. In ambient air, CO2 partial pressure at the carboxylation sites of Rubisco was 109 µbar. Internal diffusion is limited by a thick leaf consisting of densely packed, succulent mesophyll with a small portion of airspace. We speculate that a low internal conductance to CO2 diffusion results from the compromise between a succulent mesophyll required for C4 acid storage and access for CO2 diffusion to both PEPC in the cytoplasm and Rubisco in the chloroplasts. Restricted diffusion of CO2 within the leaf makes CO2 assimilation less efficient during the transient phases of crassulacean acid metabolism.

scholarly journals Information encoded in volumes and areas of dendritic spines is nearly maximal across mammalian brains

2021 ◽  
Author(s):  
Jan Karbowski ◽  
Paulina Urban
Keyword(s):  
Dendritic Spines ◽  
Excitatory Synapses ◽  
Information Efficiency ◽  
Spine Length ◽  
Entropy Maximization ◽  
Surface Areas ◽  
Heavy Tailed Distributions ◽  
Mean Size ◽  
Heavy Tailed

Long-term information associated with neuronal memory resides in dendritic spines. However, spines can have a limited size due to metabolic and neuroanatomical constraints, which should effectively limit the amount of encoded information in excitatory synapses. This study investigates how much information can be stored in the sizes of dendritic spines, and whether is it optimal in any sense? It is shown here, using empirical data for several mammalian brains across different regions and physiological conditions, that dendritic spines nearly maximize entropy contained in their volumes and surface areas for a given mean size. This result is essentially independent of the type of a fitting distribution to size data, as both short- and heavy-tailed distributions yield similar nearly 100 % information efficiency in the majority of cases, although heavy-tailed distributions slightly better fit the data. On average, the highest information is contained in spine volume, and the lowest in spine length or spine head diameter. Depending on a species and brain region, a typical spine can encode between 6.1 and 10.8 bits of information in its volume, and 3.1-8.1 bits in its surface area. Our results suggest a universality of entropy maximization in spine volumes and areas, which can be a new principle of memory storing in synapses.

scholarly journals Antioxidant responses of peanut (Arachis hypogaea L.) seedlings to prolonged salt-induced stress

2015 ◽  
Vol 67 (4) ◽  
pp. 1303-1312 ◽  
Author(s):  
Musa Kavas ◽  
Oya Akça ◽  
Ufuk Akçay ◽  
Begüm Peksel ◽  
Seçkin Eroğlu ◽  
...  
Keyword(s):  
Salinity Stress ◽  
Growth Parameters ◽  
Ion Leakage ◽  
Stress Growth ◽  
Salt Treatment ◽  
Antioxidant Responses ◽  
Stress Protection ◽  
Arachis Hypogaea L ◽  
Leaf Tissues

In this study, the effects of long-term NaCl treatment were investigated in two cultivars of peanut designated as drought-resistant and drought-sensitive. Growth parameters, changes in the concentrations of MDA, H2O2 and proline, and the activities of antioxidant enzymes were determined under salinity stress. Growth parameters indicated the superiority of cv. Florispan to cv. Gazipa?a under milder salinity stress treatment. However, comparative analysis of the two cultivars showed that MDA, H2O2, ion leakage levels and photosystem II activities were not significantly different, except for the proline activity, which increased only in Florispan leaf tissues under 100 mM salt treatment. Among the processes that govern the tolerance in peanut tissues, proline level and the activity of glutathione reductase (GR) appeared to be only components that play an important part in salt stress protection.

Zinc deficiency in wheat and lupins in Western Australia is affected by the source of phosphate fertiliser

1992 ◽  
Vol 32 (4) ◽  
pp. 455 ◽  
Author(s):  
MM Riley ◽  
JW Gartrell ◽  
RF Brennan ◽  
J Hamblin ◽  
P Coates
Keyword(s):  
Western Australia ◽  
Zn Deficiency ◽  
Single Superphosphate ◽  
Rock Phosphates ◽  
Phosphate Fertiliser ◽  
Leaf Tissues ◽  
Natural Component ◽  
Residual Effectiveness ◽  
Term Field

A long-term field experiment is being conducted in the wheatbelt of Western Australia to determine the effects of source of phosphate fertiliser on the residual effectiveness of zinc (Zn) to wheat and to sweet, narrow-leafed lupins grown in rotation. The initial 2 years' results of that experiment reported here indicate that both wheat and lupins responded to the addition of Zn to the soil. The requirements of these crops for Zn, can be mostly met with the small amount of Zn that is a natural component in single superphosphate manufactured from rock phosphates, but not with diammonium phosphate (DAP). The internal requirements for Zn of the aboveground tissues of lupins appear greater than those of wheat. Depending on the stage of growth, critical concentrations of Zn in the youngest leaf tissues of wheat that were prognostic of Zn deficiency, were found to vary from about 7 to 16 �g/g, while those in lupins were found to vary from about 28 to 37 �g/g.

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