scholarly journals The evolution of abscisic acid (ABA) and ABA function in lower plants, fungi and lichen

2010 ◽  
Vol 37 (9) ◽  
pp. 806 ◽  
Author(s):  
Wolfram Hartung
Keyword(s):  
Abscisic Acid ◽  
External Medium ◽  
Higher Plants ◽  
Regulatory Function ◽  
Physiological Concentration ◽  
Mycorrhizal Associations ◽  
Terrestrial Habitats ◽  
High Concentrations ◽  
Cyanobacteria And Algae ◽  
Almost All

Abscisic acid (ABA) – the universal stress hormone of cormophytes – was detected in very low concentrations in almost all organisms tested from a range of cyanobacteria, algae, bryophytes, fungi and lichens and higher plants (Fig. 1). There are a few reports only on stress-induced ABA biosynthesis in cyanobacteria and algae. This extra ABA is released to the external medium. Application of external ABA has been shown to produce weak and contradicting effects on development and metabolism of algae. In most studies, extremely high concentrations of external ABA have been applied, those being far beyond any physiological concentration range. It is, therefore, extremely difficult to discuss those data satisfactorily. When organisms start to colonise terrestrial habitats (e.g. aquatic liverworts, mosses), endogenous ABA is increased even under mild drought stress, then desiccation protecting mechanisms are stimulated and the formation of terrestrial organs is induced. The same can be observed in water ferns (Marsilea) and in a range of heterophyllous angiosperms. Sporophytes of hornwort and mosses that bear true stomata, have particularly high ABA levels and their stomata respond to ABA as is the case in cormophytes, although a significant regulatory function of these stomata does not exist. Fungi produce large amounts of ABA that are released into the external medium and do not seem to have a function for the fungus. Fungal ABA, however, may be significant in associations of fungi with cyanophytes and algae (lichens), in mycorrhizal associations and in the rhizosphere of higher plants.

The possible rôle of xanthoxin in plant growth and development

1978 ◽  
Vol 284 (1002) ◽  
pp. 499-507 ◽  
Keyword(s):  
Abscisic Acid ◽  
Hormonal Regulation ◽  
Growth And Development ◽  
Higher Plants ◽  
The Other ◽  
Regulatory Function ◽  
Root Tip ◽  
Root Tips ◽  
Root Primordia ◽  
Lateral Root Primordia

In higher plants, abscisic acid and xanthoxin are two potent growth regulators. Although similar properties in both substances have been demonstrated in several biological tests including biochemical interconversion of the substances, evidence is available that in the plant as a whole, xanthoxin has regulatory functions other than those of abscisic acid. Several environmental factors, such as water supply, photoperiod and low temperature, which affect growth and development also greatly change the level of abscisic acid in the plant; however, only small variations in the xanthoxin level have been observed in response to changes in the environmental conditions. On the other hand, a strong enhancement of the xanthoxin level can be induced when dark-grown seedlings are briefly illuminated; this treatment, however, has no influence on the abscisic acid level. This observation supports the hypothesis that light-induced inhibition of growth may be mediated by an increased formation of the growth inhibitor xanthoxin. Light-induced enhancement of the xanthoxin level may also contribute to the phototropic bending in dictyledonous seedlings. Evidence has been obtained from experiments in this laboratory that xanthoxin may be involved in the regulation of root branching. Decapitation of root tips causes a significant increase in the number of lateral root primordia. Chromatographic studies reveal the presence of two substances in the root, which, in a specific bioassay, are active inhibitors of the development of root primordia. The activity of these root inhibitors in the basal part decreases when the root tip is removed. They are probably produced in the root tip and are transported to the base. One of these inhibitors has been identified as xanthoxin, the other is cytokinin. The hormonal regulation of abscission is another process where xanthoxin may have a regulatory function. Senescent, abscinding petioles contain a factor called ‘senescence factor’ which promotes the abscission of leaves. In an attempt to identify its chemical nature, it was found that at least three different abscission accelerating substances, including xanthoxin, participate in the composition of the senescence factor.

scholarly journals Effects of Strontium on the Permeation and Gating Phenotype of Calcium Channels in Hair Cells

2008 ◽  
Vol 100 (4) ◽  
pp. 2115-2124 ◽  
Author(s):  
Adrian Rodriguez-Contreras ◽  
Ping Lv ◽  
Jun Zhu ◽  
Hyo Jeong Kim ◽  
Ebenezer N. Yamoah
Keyword(s):  
Hair Cell ◽  
Single Channel ◽  
Single Channels ◽  
Physiological Concentration ◽  
Closed State ◽  
Dependent Inactivation ◽  
Intracellular Ca ◽  
High Concentrations ◽  
Latency Distributions ◽  
Channel Properties

To minimize the effects of Ca2+ buffering and signaling, this study sought to examine single Ca2+ channel properties using Sr2+ ions, which substitute well for Ca2+ but bind weakly to intracellular Ca2+ buffers. Two single-channel fluctuations were distinguished by their sensitivity to dihydropyridine agonist (L-type) and insensitivity toward dihydropyridine antagonist (non-L-type). The L- and non-L-type single channels were observed with single-channel conductances of 16 and 19 pS at 70 mM Sr2+ and 11 and 13 pS at 5 mM Sr2+, respectively. We obtained KD estimates of 5.2 and 1.9 mM for Sr2+ for L- and non-L-type channels, respectively. At Ca2+ concentration of ∼2 mM, the single-channel conductances of Sr2+ for the L-type channel was ∼1.5 and 4.0 pS for the non-L-type channels. Thus the limits of single-channel microdomain at the membrane potential of a hair cell (e.g., −65 mV) for Sr2+ ranges from 800 to 2,000 ion/ms, assuming an ECa of 100 mV. The channels are ≥4-fold more sensitive at the physiological concentration ranges than at concentrations >10 mM. Additionally, the channels have the propensity to dwell in the closed state at high concentrations of Sr2+, which is reflected in the time constant of the first latency distributions. It is concluded that the concentration of the permeant ion modulates the gating of hair cell Ca2+ channels. Finally, the closed state/s that is/are altered by high concentrations of Sr2+ may represent divalent ion-dependent inactivation of the L-type channel.

Detection of Biogenic Amine Producer Bacteria in a Typical Italian Goat Cheese

2008 ◽  
Vol 71 (1) ◽  
pp. 205-209 ◽  
Author(s):  
SILVIA BONETTA ◽  
SARA BONETTA ◽  
ELISABETTA CARRARO ◽  
JEAN DANIEL COÏSSON ◽  
FABIANO TRAVAGLIA ◽  
...  
Keyword(s):  
Biogenic Amines ◽  
Enterococcus Faecalis ◽  
Biogenic Amine ◽  
Pediococcus Acidilactici ◽  
Bacterial Strains ◽  
Goat Cheese ◽  
Low Concentrations ◽  
Amine Content ◽  
High Concentrations ◽  
Almost All

The aim of this study was to research decarboxylating bacterial strains and biogenic amine content in a typical Italian goat cheese (Robiola di Roccaverano). The study was performed on fresh and ripened samples of goat cheese manufactured from industrial and artisanal producers. Sixty-seven bacterial strains isolated showed decarboxylating activity, and Enterococcus faecalis was the most widespread decarboxylating species in all artisanal and industrial products. Pediococcus acidilactici and Enterococcus malodoratus were also identified as biogenic amine producers in Robiola di Roccaverano cheese. All the E. faecalis strains isolated in this study were able to decarboxylate tyrosine. Tyramine was the most abundant biogenic amine in cheese samples, while histamine was the most widespread. High amounts of these two biogenic amines were found in ripened samples (up to 2,067 mg/kg for tyramine and 1,786 mg/kg for histamine), whereas 2-phenylethylamine and tryptamine were present in almost all ripened cheeses at low concentrations. The detection of strains producing biogenic amines and the high concentrations of tyramine and histamine found in ripened Robiola di Roccaverano could represent a potential risk to the consumer.

Efficacy of manufactured PIGOUT® baits for localised control of feral pigs in the semi-arid Queensland rangelands

2006 ◽  
Vol 33 (5) ◽  
pp. 427 ◽  
Author(s):  
Brendan D. Cowled ◽  
Eddie Gifford ◽  
Michelle Smith ◽  
Linton Staples ◽  
Steven J. Lapidge
Keyword(s):  
Significant Risk ◽  
Population Census ◽  
Population Declines ◽  
Feral Pigs ◽  
Remote Cameras ◽  
High Concentrations ◽  
Almost All ◽  
Bait Stations ◽  
Semi Arid ◽  
Feral Pig

Conservative population declines of 73% were recorded in three independent feral pig populations in Welford National Park, Queensland, when PIGOUT® baits containing 72 mg of sodium fluoroacetate were used in a baiting program following prefeeding. Declines were measured using a prebaiting population census with remote cameras, followed by carcass recovery. The knockdown of susceptible feral pigs may have been higher than this, since any carcasses not recovered reduced the recorded efficacy. In addition, feral pigs know to have left the baiting area after trapping and telemetry-tagging, and subsequently not exposed to toxic baits, were included in the analysis. The use of remote cameras and carcass recovery appears to be a relatively accurate means of recording localised declines in feral pig populations. This method is applicable only when carcass recovery is possible, such as in open areas in the semi-arid rangelands. A decline of 86% of radio-tagged feral pigs attending bait stations was also recorded. Camera observations revealed no non-target consumption of baits. Measurement of sodium fluoroacetate–contaminated tissues from feral pigs showed that residues were too low to present a significant risk to recorded scavenging animals in the area. Some feral pigs vomited before death, with vomitus containing sodium fluoroacetate poison at high concentrations. No vomitus was consumed by non-target species. Almost all feral pigs were killed relatively rapidly after ingestion of sodium fluoroacetate and the signs observed in a small number of poisoned feral pigs did not indicate a significant welfare concern.

Partial dissociation of nitrogen aggregates in diamond by high temperature-high pressure treatments

1978 ◽  
Vol 361 (1704) ◽  
pp. 109-127 ◽  
Keyword(s):  
General Relation ◽  
Infrared Region ◽  
Optical Measurements ◽  
Type I ◽  
Paramagnetic Resonance ◽  
High Concentrations ◽  
Partial Dissociation ◽  
Almost All ◽  
Electron Paramagnetic

Type I (a) diamonds contain high concentrations of nitrogen, almost all of which is in an aggregated form. The two main aggregates are recognized by characteristic absorption features in the infrared region of the spectrum. These are called A and B features; usually a peak designated B' is also present. When such diamonds were heated at 1960 °C and above under a stabilizing pressure of 85kbar (8.5 GPa) the nitrogen aggregates partially dissociated, producing single substitutional atoms which were identified by electron paramagnetic resonance (e.p.r.) measurements. Experiments with selected diamonds, showing wide variations in their characteristic infrared absorption, determined the relative stability of the A and B centres. Optical measurements led to the determination of a general relation between the strengths of the A, B and B' features. The experimental observations suggest a scheme for the occurrence of type I (a) diamonds containing nitrogen atoms which have aggregated into A centres; type I (b) diamonds can also be included in this scheme.

Crosstalk between nitric oxide (NO) and abscisic acid (ABA) signalling molecules in higher plants

2019 ◽  
Vol 161 ◽  
pp. 41-49 ◽  
Author(s):  
Ved Prakash ◽  
Vijay Pratap Singh ◽  
Durgesh Kumar Tripathi ◽  
Shivesh Sharma ◽  
Francisco J. Corpas
Keyword(s):  
Nitric Oxide ◽  
Abscisic Acid ◽  
Higher Plants ◽  
Signalling Molecules

RNA, PROTEIN AND DNA SYNTHESIS STIMULATED BY TESTOSTERONE, INSULIN AND PROLACTIN IN THE RAT VENTRAL PROSTATE CULTURED IN CHEMICALLY DEFINED MEDIUM

1975 ◽  
Vol 80 (4) ◽  
pp. 761-774 ◽  
Author(s):  
Risto Johansson
Keyword(s):  
Response Times ◽  
Defined Medium ◽  
Ventral Prostate ◽  
Chemically Defined Medium ◽  
Physiological Concentration ◽  
Rat Ventral Prostate ◽  
Organ Type ◽  
High Concentrations ◽  
H Protein

ABSTRACT In an organ type tissue culture of the rat ventral prostate in a chemically defined medium insulin (0.08 IU/ml) stimulated the synthesis of RNA within 6–12 h, the synthesis of protein within 6–12 h and the synthesis of DNA within 2–4 days. Testosterone (10−8 m) stimulated these synthetic processes somewhat more slowly: the synthesis of RNA within 12–24 h, protein within 12–24 h and DNA at 4 days. Rather high concentrations of insulin were needed while testosterone was effective at a physiological concentration. Prolactin (1000 ng/ml) stimulated the synthesis of RNA and protein, but not DNA, when added together with either testosterone or insulin, but was completely ineffective when added alone. The response times resembled those of insulin. The lower concentrations of prolactin were ineffective. Growth hormone, luteinizing hormone and follicle stimulating hormone did not stimulate the synthesis of RNA, protein or DNA even when added with testosterone. The results confirm the findings of the numerous in vivo experiments that the hypophyseal hormone prolactin has a direct effect on the ventral prostate.

Effects of abscisic acid and high concentrations of PEG on Hevea brasiliensis somatic embryos development

Plant Science ◽  
1997 ◽  
Vol 124 (2) ◽  
pp. 183-191 ◽  
Author(s):  
Laurent Linossier ◽  
Philippe Veisseire ◽  
Françoise Cailloux ◽  
Alain Coudret
Keyword(s):  
Abscisic Acid ◽  
Hevea Brasiliensis ◽  
Somatic Embryos ◽  
High Concentrations

The role of NO in plant response to salt stress: interactions with polyamines

2020 ◽  
Vol 47 (10) ◽  
pp. 865
Author(s):  
Natalia Napieraj ◽  
Małgorzata Reda ◽  
Małgorzata Janicka
Keyword(s):  
Salt Stress ◽  
Higher Plants ◽  
Growth Parameters ◽  
Plant Response ◽  
No Donors ◽  
Signalling Molecule ◽  
Defence Responses ◽  
High Concentrations ◽  
Ionic Effects

Soil salinity is a major abiotic stress that limits plant growth and productivity. High concentrations of sodium chloride can cause osmotic and ionic effects. This stress minimises a plant’s ability to uptake water and minerals, and increases Na+ accumulation in the cytosol, thereby disturbing metabolic processes. Prolonged plant exposure to salt stress can lead to oxidative stress and increased production of reactive oxygen species (ROS). Higher plants developed some strategies to cope with salt stress. Among these, mechanisms involving nitric oxide (NO) and polyamines (PAs) are particularly important. NO is a key signalling molecule that mediates a variety of physiological functions and defence responses against abiotic stresses in plants. Under salinity conditions, NO donors increase growth parameters, reduce Na+ toxicity, maintain ionic homeostasis, stimulate osmolyte accumulation and prevent damages caused by ROS. NO enhances salt tolerance of plants via post-translational protein modifications through S-nitrosylation of thiol groups, nitration of tyrosine residues and modulation of multiple gene expression. Several reviews have reported on the role of polyamines in modulating salt stress plant response and the capacity to enhance PA synthesis upon salt stress exposure, and it is known that NO and PAs interact under salinity. In this review, we focus on the role of NO in plant response to salt stress, paying particular attention to the interaction between NO and PAs.

scholarly journals Analogs of the Autoinducer 3-Oxooctanoyl-Homoserine Lactone Strongly Inhibit Activity of the TraR Protein ofAgrobacterium tumefaciens

1998 ◽  
Vol 180 (20) ◽  
pp. 5398-5405 ◽  
Author(s):  
Jun Zhu ◽  
John W. Beaber ◽  
Margret I. Moré ◽  
Clay Fuqua ◽  
Anatol Eberhard ◽  
...  
Keyword(s):  
Homoserine Lactone ◽  
Mass Action ◽  
Wild Type ◽  
Dna Binding Sites ◽  
Agonistic Activity ◽  
High Concentrations ◽  
Mediate Cell ◽  
Potent Antagonist ◽  
Almost All ◽  
Related Compounds

ABSTRACT The TraR and TraI proteins of Agrobacterium tumefaciensmediate cell-density-dependent expression of the Ti plasmidtra regulon. TraI synthesizes the autoinducer pheromoneN-(3-oxooctanoyl)-l-homoserine lactone (3-oxo-C8-HSL), while TraR is an 3-oxo-C8-HSL-responsive transcriptional activator. We have compared the abilities of 3-oxo-C8-HSL and 32 related compounds to activate expression of a TraR-regulated promoter. In a strain that expresses wild-type levels of TraR, only 3-oxo-C8-HSL was strongly stimulatory, four compounds were detectably active only at high concentrations, and the remaining 28 compounds were inactive. Furthermore, many of these compounds were potent antagonists. In contrast, almost all of these compounds were stimulatory in a congenic strain that overexpresses TraR and no compound was a potent antagonist. We propose a model in which autoinducers enhance the affinity of TraR either for other TraR monomers or for DNA binding sites and that overexpression of TraR potentiates this interaction by mass action. Wild-type A. tumefaciens released a rather broad spectrum of autoinducers, including several that antagonize induction of a wild-type strain. However, under all conditions tested, 3-oxo-C8-HSL was more abundant than any other analog, indicating that other released autoinducers do not interfere with tra gene induction. We conclude that (i) in wild-type strains, only 3-oxo-C8-HSL significantly stimulates tra gene expression, while many autoinducer analogs are potent antagonists; (ii) TraR overexpression increases agonistic activity of autoinducer analogs, allowing sensitive biodetection of many autoinducers; and (iii) autoinducer stimulatory activity is potentiated by TraR overproduction, suggesting that autoinducers may shift an equilibrium between TraR monomers and dimers or oligomers. When autoinducer specificities of other quorum-sensing proteins are tested, care should be taken not to overexpress those proteins.

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