scholarly journals On the Ecology of Selenium Accumulation in Plants

Plants ◽  
2019 ◽  
Vol 8 (7) ◽  
pp. 197 ◽  
Author(s):  
Elizabeth A. H. Pilon-Smits
Keyword(s):  
Dry Weight ◽  
Ecological Impacts ◽  
Trophic Levels ◽  
Future Research ◽  
Negative Effects ◽  
Low Concentrations ◽  
Elemental Defense ◽  
Litter Deposition ◽  
High Concentrations ◽  
Local Ecosystem

Plants accumulate and tolerate Se to varying degrees, up to 15,000 mg Se/kg dry weight for Se hyperaccumulators. Plant Se accumulation may exert positive or negative effects on other species in the community. The movement of plant Se into ecological partners may benefit them at low concentrations, but cause toxicity at high concentrations. Thus, Se accumulation can protect plants against Se-sensitive herbivores and pathogens (elemental defense) and reduce surrounding vegetation cover via high-Se litter deposition (elemental allelopathy). While hyperaccumulators negatively impact Se-sensitive ecological partners, they offer a niche for Se-tolerant partners, including beneficial microbial and pollinator symbionts as well as detrimental herbivores, pathogens, and competing plant species. These ecological effects of plant Se accumulation may facilitate the evolution of Se resistance in symbionts. Conversely, Se hyperaccumulation may evolve driven by increasing Se resistance in herbivores, pathogens, or plant neighbors; Se resistance also evolves in mutualist symbionts, minimizing the plant’s ecological cost. Interesting topics to address in future research are whether the ecological impacts of plant Se accumulation may affect species composition across trophic levels (favoring Se resistant taxa), and to what extent Se hyperaccumulators form a portal for Se into the local food chain and are important for Se cycling in the local ecosystem.

scholarly journals ALLELOPATHIC INFLUENCE OF TRIANTHIMA PORTULACASTRUM L. ON GROWTH AND DEVELOPMENTAL RESPONSES OF SESAME (SESAMUM INDICUM L.)

2017 ◽  
Vol 4 (2) ◽  
pp. 183-186
Author(s):  
Prabhakaran J ◽  
Kavitha D
Keyword(s):  
Block Design ◽  
Dry Weight ◽  
Germination Percentage ◽  
Sesamum Indicum ◽  
Negative Effects ◽  
Chlorophyll Contents ◽  
Whole Plant ◽  
Low Concentrations ◽  
Seedling Length ◽  
Developmental Responses

An experiment was conducted in order to determine the allelopathic effects of the aqueous extract of Trianthima portulacastrum L.on the seed germination, seedling growth and chlorophyll content ofsesame (Sesamum indicum L.). Greenhouse experiment was carried out as RCBD (Randomized complete block design)with four replications. Treatments included 0, 1, 2, 3 and 4% (W/W) residues of whole plant of T.portulacastrum with normal field soil. Results showed that the low concentrations of T.portulacastrum had no significant effect on the germination percentage, seedling length, dry weight, total chlorophyll contents at lower concentration(1%) of weed residues. However, treatments with higher concentrations had negative effects on germination, growth and seedling dry weight of sesame.

scholarly journals A Cytochemical Study on the Pancreas of the Guinea Pig

1960 ◽  
Vol 7 (4) ◽  
pp. 631-644 ◽  
Author(s):  
Philip Siekevitz ◽  
George E. Palade
Keyword(s):  
Molecular Structure ◽  
Guinea Pig ◽  
Incubation Medium ◽  
Sedimentation Coefficient ◽  
Dry Weight ◽  
Analytical Ultracentrifuge ◽  
Cytochemical Study ◽  
Low Concentrations ◽  
Proteolytic Activities ◽  
High Concentrations

Ribonucleoprotein (RNP)1 particles isolated by DOC treatment from pancreatic microsomes have a RNA content of 35 to 45 per cent of their dry weight. In the analytical ultracentrifuge about 85 per cent of the material has a sedimentation coefficient of ∼85 S. These particles contain amylase, RNase, and trypsin-activatable proteolytic activities which cannot be washed off or detached by incubation in 0.44 M sucrose. The enzymes are released, however, by incubation in the presence of low concentrations of ATP, PP, or EDTA, and high concentrations of IP and AMP. At the same time, and at the same concentrations, ∼80 per cent of the RNA and ∼25 per cent of the protein of the particles becomes also non-sedimentable. The simultaneous addition of Mg++ to the incubation medium prevents these losses. This finding, together with the observation that all the Mg++ of the particles is released by the same agents, makes it likely that Mg++ holds the particles together, and that its removal by the chelators used causes the particles to disintegrate. These findings are discussed in relation to the molecular structure of the RNP particles.

scholarly journals Comparative effect of Nickel and beta-aminobutiric Acid on some Secondary Metabolits of Echium amoenum

2015 ◽  
Vol 9 (5) ◽  
pp. 25-30 ◽  
Author(s):  
Peyman Rajaei ◽  
Neda Mohamadi
Keyword(s):  
Secondary Metabolites ◽  
Dry Weight ◽  
Aminobutyric Acid ◽  
Stress Effects ◽  
Low Concentrations ◽  
Iranian Traditional Medicine ◽  
Wonderful Variety ◽  
Research Findings ◽  
Echium Amoenum ◽  
High Concentrations

Plants have a wonderful variety of secondary metabolites which may be change due to environmental factors and stress conditions. Considering the importance of Echium amoenum in Iranian traditional medicine, this study aimed to investigate the effect of abiotic stresses on the possibility of further production of secondary metabolites in the plant. In general, according our research findings, beta-aminobutyric acid increased growth indexes. Effect of BABA on secondary metabolites was different. BABA increased plant flavonoids but reduced the tannins. Numerous studies have pointed to the stress effects of this material at high concentrations but the concentrations used in this study increased the plant growth. Nickel in applied concentrations had no significant reduction in plant dry weight but increased the photosynthetic pigments. Ni increased plant flavonoids but reduced the tannins. Nickel and beta-aminobutyric acid at low concentrations, is recommended to use for greater production of secondary metabolites in Echium cultivation.DOI: http://dx.doi.org/10.3126/ijls.v9i5.12687

scholarly journals EFFECTS OF K-IBA AND RADICLE-CLIPPING TREATMENTS ON ROOT DEVELOPMENT OF NORTHERN RED OAK

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 607f-607
Author(s):  
Daniel G. Krueger ◽  
Bert T. Swanson
Keyword(s):  
Root Development ◽  
Quercus Rubra ◽  
Dry Weight ◽  
Root Systems ◽  
Red Oak ◽  
Northern Red Oak ◽  
Stem Height ◽  
Root Dry Weight ◽  
Low Concentrations ◽  
High Concentrations

To increase root fibrosity, acorns of northern red oak (Quercus rubra L.) were germinated and subjected to several radicle clipping (+/-) and K-IBA concentration treatments combintations prior to planting. Taproots and laterals ≥ 1 mm in diameter at the point of origin were counted. Low concentrations of K-IBA (0-4000 ppm) resulted in four root morphologies: 1) a single taproot and 3-6 laterals (no clipping/no K-IBA), 2) 4-5 taproots and 1-3 laterals (clipped only), 3) a single taproot and 5-12 laterals (not clipped/K-IBA) and 4) 6-12 taproots and 1-2 laterals. High concentrations of K-IBA (4000-10,000 ppm) `clipped' unclipped radicles resulting in root systems similiar to those clipped by hand. Stem height was unaffected by treatment. Radicle-clipping may increase stem caliper. K-IBA treatments may decrease root dry weight.

Effect of Body Size on Accumulation of Po210 in Mussel, Perna viridis, at Samut Sakhon Province

2014 ◽  
Vol 931-932 ◽  
pp. 624-628 ◽  
Author(s):  
Boonsom Porntepkasemsan ◽  
Kanitha Srisuksawad ◽  
Vorapot Permnamthip
Keyword(s):  
Body Size ◽  
Body Burden ◽  
Seasonal Fluctuation ◽  
Dry Weight ◽  
Condition Index ◽  
Seasonal Effect ◽  
Perna Viridis ◽  
Wet Season ◽  
Low Concentrations ◽  
High Concentrations

Levels of 210Po in mussel (Perna viridis) collected from green mussel farming area at the Samut Sakhon province during the period of 2012 are presented. Parameters including total tissues wet weight and dry weight, maximum length, and the physiological performance of mussels using Condition Index were measured. The type of fluctuations observed with 210Po concentrations are interpreted as a seasonal effect which peaks of high concentrations in wet season and low concentrations in dry season. Analysis of 210Po activities in mussel (activity per individual) revealed the lower activities in smaller sized mussels (2.0-2.5 cm) and the higher in the larger sized group (6.5-7.0 cm). In the contrary, 210Po concentrations decreased with increasing shell length, or with increasing body size. The 210Po body burdens (activity per mussel) varied from 2.413 to 17.183 mBq while the 210Po concentrations were ranged from 2.511 to 4.474 Bq.Kg-1 ww. The results indicated that larger mussels were transfer lower 210Po concentrations to consumer on a weight basis. It is concluded that the apparent seasonal fluctuation of radionuclide concentration were mostly caused by mussel body size fluctuation and not by radionuclide body burden fluctuation.

Effect of 2,4-D on Ametryne Toxicity

Weed Science ◽  
1974 ◽  
Vol 22 (3) ◽  
pp. 285-292 ◽  
Author(s):  
J. R. Diem ◽  
D. E. Davis
Keyword(s):  
Zea Mays ◽  
Acetic Acid ◽  
Glycine Max ◽  
Dry Weight ◽  
Low Concentrations ◽  
High Concentrations ◽  
Eichornia Crassipes ◽  
Dichlorophenoxy Acetic Acid ◽  
Toxic Concentrations ◽  
Species Mixtures

Nontoxic concentrations of 2,4-D [(2,4-dichlorophenoxy)acetic acid] increased the toxicity of ametryne [2-(ethylamino)-4-(isopropylamino)-6-(methylthio)-s-triazine], when applied to the roots of waterhyacinth [Eichornia crassipes(Mart.) Solms], when applied to the roots or foliage of corn (Zea maysL.), and to a lesser extent, when applied to the roots of soybean [Glycine max(L.) Merr.]. Nontoxic concentrations of 2,4-D frequently also increased the absorption of ametryne, water, and radioactive calcium by all three species. Mixtures containing toxic concentrations of 2,4-D with ametryne were not synergistic and sometimes the mixtures were less toxic than ametryne alone. Toxic concentrations of 2,4-D also decreased plant dry weight and the absorption of ametryne, water, and calcium. Low concentrations of ametryne increased the absorption of water and sometimes calcium while high concentrations decreased dry weight and the absorption of water and calcium.

scholarly journals Leaching from leaves of Sarcomphalus joazeiro and Cenostigma bracteosum stimulate or inhibit the germination of Mimosa caesalpiniifolia?

2021 ◽  
Vol 10 (3) ◽  
pp. e15610313073
Author(s):  
Fernando dos Santos Araújo ◽  
Josenilda Aprígio Dantas de Medeiros ◽  
Francival Cardoso Félix ◽  
Luiz Augusto da Silva Correia ◽  
Cibele dos Santos Ferrari ◽  
...  
Keyword(s):  
Seed Germination ◽  
Primary Root ◽  
Dry Weight ◽  
Forest Composition ◽  
Initial Growth ◽  
Leaf Extracts ◽  
Allelopathic Potential ◽  
Low Concentrations ◽  
High Concentrations ◽  
And Control

Allelopathy is an ecological mechanism that influences the development of neighboring plants. The objective was to evaluate the allelopathic potential of Cenostigma bracteosum and Sarcomphalus joazeiro on seed germination and initial growth of Mimosa caesalpiniifolia seedlings. Seeds of this species were placed to germinate on paper towel substrate, and then moistened with extracts from dry leaf of S. joazeiro and C. bracteosum at 1.0; 2.5; 5.0 and 10.0% (w.v-1), and control (0.0% - distilled water) at 25 °C. The variables evaluated: germination, germination speed index, primary root length and root system dry weight of the seedlings. Positive allelopathic effects of S. joazeiro leaf extracts were observed on the vigor of M. caesalpiniifolia; when used in low concentrations (up to 2.6%), C. bracteosum leaf extracts stimulated germination of M. caesalpiniifolia seeds and showed more severe toxic effects when exposed to high concentrations (5.0%). S. joazeiro leaf extracts favor the germination and vigor of M. caesalpiniifolia seedlings, while C. bracteosum leaf extracts cause phytotoxic effects on seed germination and initial growth of M. caesalpiniifolia seedlings from the concentration of 5%. Therefore, there are indications of benefits for regeneration or associated forest composition between M. caesalpiniifolia and S. joazeiro.

Neutrophil Elastase Potentiates Cathepsin G-lnduced Platelet Activation

1992 ◽  
Vol 68 (05) ◽  
pp. 570-576 ◽  
Author(s):  
Mary A Selak
Keyword(s):  
Neutrophil Elastase ◽  
Cell Activation ◽  
Thromboxane A2 ◽  
Creatine Phosphate ◽  
Dense Granule ◽  
Cathepsin G ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Low Concentrations ◽  
High Concentrations

SummaryWe have previously demonstrated that human neutrophil cathepsin G is a strong platelet agonist that binds to a specific receptor. This work describes the effect of neutrophil elastase on cathepsin G-induced platelet responses. While platelets were not activated by high concentrations of neutrophil elastase by itself, elastase enhanced aggregation, secretion and calcium mobilization induced by low concentrations of cathepsin G. Platelet aggregation and secretion were potentiated in a concentration-dependent manner by neutrophil elastase with maximal responses observable at 200 nM. Enhancement was observed when elastase was preincubated with platelets for time intervals of 10–60 s prior to addition of a low concentration of cathepsin G and required catalytically-active elastase since phenylmethanesulphonyl fluoride-inhibited enzyme failed to potentiate cell activation. Neutrophil elastase potentiation of platelet responses induced by low concentrations of cathepsin G was markedly inhibited by creatine phosphate/creatine phosphokinase and/or indomethacin, indicating that the synergism between elastase and cathepsin G required the participation of ADP and thromboxane A2. On the other hand, platelet responses were not attenuated by the PAF antagonist BN 52021, signifying that PAF-acether did not play a role in elastase potentiation. At higher concentrations porcine pancreatic elastase exhibits similar effects to neutrophil elastase, demonstrating that the effect of elastase was not unique to the neutrophil protease. While neutrophil elastase failed to alter the ability of cathepsin G to hydrolyze a synthetic chromogenic substrate, preincubation of platelets with elastase increased the apparent affinity of cathepsin G binding to platelets. In contrast to their effect on cathepsin G-induced platelet responses, neither neutrophil nor pancreatic elasatse potentiated aggregation or dense granule release initiated by ADP, PAF-acether, arachidonic acid or U46619, a thromboxane A2 mimetic. Moreover, unlike its effect on cathepsin G, neutrophil elastase inhibited thrombin-induced responses. The current observations demonstrate that elastase can potentiate platelet responses mediated by low concentrations of cathepsin G, suggesting that both enzymes may function synergistically to activate platelets under conditions where neutrophil degranulation occurs.

In Vitro Effects of Ethanol on Rabbit Platelet Aggregation, Secretion of Granule Contents, and Cyclic AMP Levels in the Presence of Prostacyclin

1989 ◽  
Vol 61 (02) ◽  
pp. 254-258 ◽  
Author(s):  
Margaret L Rand ◽  
Peter L Gross ◽  
Donna M Jakowec ◽  
Marian A Packham ◽  
J Fraser Mustard
Keyword(s):  
Cyclic Amp ◽  
Inhibitory Effect ◽  
Rabbit Platelet ◽  
Inhibitory Effects ◽  
Low Concentrations ◽  
Rabbit Platelets ◽  
High Concentrations ◽  
In Vitro Effects ◽  
Aggregation Of Platelets

SummaryEthanol, at physiologically tolerable concentrations, inhibits platelet responses to low concentrations of collagen or thrombin, but does not inhibit responses of washed rabbit platelets stimulated with high concentrations of ADP, collagen, or thrombin. However, when platelet responses to high concentrations of collagen or thrombin had been partially inhibited by prostacyclin (PGI2), ethanol had additional inhibitory effects on aggregation and secretion. These effects were also observed with aspirin- treated platelets stimulated with thrombin. Ethanol had no further inhibitory effect on aggregation of platelets stimulated with ADP, or the combination of ADP and epinephrine. Thus, the inhibitory effects of ethanol on platelet responses in the presence of PGI2 were very similar to its inhibitory effects in the absence of PGI2, when platelets were stimulated with lower concentrations of collagen or thrombin. Ethanol did not appear to exert its inhibitory effects by increasing cyclic AMP above basal levels and the additional inhibitory effects of ethanol in the presence of PGI2 did not appear to be brought about by further increases in platelet cyclic AMP levels.

Aggregation of Cat Platelets in Vitro

1970 ◽  
Vol 23 (03) ◽  
pp. 601-620 ◽  
Author(s):  
Th. B Tschopp
Keyword(s):  
Adenosine Monophosphate ◽  
Blood Collection ◽  
Base Line ◽  
Reversible Aggregation ◽  
Low Concentrations ◽  
Irreversible Aggregation ◽  
High Concentrations ◽  
Two Phases ◽  
Improved Technique

SummaryAggregation of cat platelets in the citrated plasma is examined by means of Born’s absorptiometer. A marked tendency of the platelets of this species to spontaneous aggregation necessitated first of all the development of an improved technique of blood collection.A hypothesis according to which 5-HT is released from the platelets, explains the absence of oscillations on the base line of the absorptiometer, the absence of platelet swelling, when ADP is added, and the effect of stirring on the aggregation curves in cat PRP. The average volume of cat platelets amounts to 10.46 μ3 when directly fixed in the blood, when fixed from PRP to 12.17 μ3, when fixed from stirred PRP to 13.51 μ3.In low concentrations (0.3-2 μM) ADP produce reversible aggregation; in narrowly restricted, individually dissimilar mean concentrations irreversible aggregation in two phases and in high concentrations, irreversible aggregation in one phase. Like ADP serotonin produces 2 phase irreversible aggregation in concentrations of 3-10 μM, but unlike ADP, the aggregation velocity decreases again with high 5-HT concentrations (>100 μM). Adrenaline does not produce aggregation and it is likely that adenosine and adenosine monophosphate inhibit the aggregation by serotonin but not by ADP. Species differences in the aggregation of human, rabbit and cat platelets are discussed.

Sign in / Sign up

Export Citation Format

Share Document