87 research outputs found
Changes in expression level of OsHKT1;5 alters activity of membrane transporters involved in K+ and Ca2+ acquisition and homeostasis in salinized rice roots
In rice, the OsHKT1;5 gene has been reported to be a critical determinant of salt tolerance. This gene is harbored by the SKC1 locus, and its role was attributed to Na+ unloading from the xylem. No direct evidence, however, was provided in previous studies. Also, the reported function of SKC1 on the loading and delivery of K+ to the shoot remains to be explained. In this work, we used an electrophysiological approach to compare the kinetics of Na+ uptake by root xylem parenchyma cells using wild type (WT) and NIL(SKC1) plants. Our data showed that Na+ reabsorption was observed in WT, but not NIL(SKC1) plants, thus questioning the functional role of HKT1;5 as a transporter operating in the direct Na+ removal from the xylem. Instead, changes in the expression level of HKT1;5 altered the activity of membrane transporters involved in K+ and Ca2+ acquisition and homeostasis in the rice epidermis and stele, explaining the observed phenotype. We conclude that the role of HKT1;5 in plant salinity tolerance cannot be attributed to merely reducing Na+ concentration in the xylem sap but triggers a complex feedback regulation of activities of other transporters involved in the maintenance of plant ionic homeostasis and signaling under stress conditions
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Prebiotic potential of a maize-based soluble fibre and impact of dose on the human gut microbiota
Dietary management of the human gut microbiota towards a more beneficial composition is one approach that may improve host health. To date, a large number of human intervention studies have demonstrated that dietary consumption of certain food products can result in significant changes in the composition of the gut microbiota i.e. the prebiotic concept. Thus the prebiotic effect is now established as a dietary approach to increase beneficial gut bacteria and it has been associated with modulation of health biomarkers and modulation of the immune system. Promitor™ Soluble Corn Fibre (SCF) is a well-known maize-derived source of dietary fibre with potential selective fermentation properties. Our aim was to determine the optimum prebiotic dose of tolerance, desired changes to microbiota and fermentation of SCF in healthy adult subjects. A double-blind, randomised, parallel study was completed where volunteers (n = 8/treatment group) consumed 8, 14 or 21 g from SCF (6, 12 and 18 g/fibre delivered respectively) over 14-d. Over the range of doses studied, SCF was well tolerated Numbers of bifidobacteria were significantly higher for the 6 g/fibre/day compared to 12g and 18g/fibre delivered/day (mean 9.25 and 9.73 Log10 cells/g fresh faeces in the pre-treatment and treatment periods respectively). Such a numerical change of 0.5 Log10 bifidobacteria/g fresh faeces is consistent with those changes observed for inulin-type fructans, which are recognised prebiotics. A possible prebiotic effect of SCF was therefore demonstrated by its stimulation of bifidobacteria numbers in the overall gut microbiota during a short-term intervention
Effects of Salt Stress on Three Ecologically Distinct Plantago Species
Comparative studies on the responses to salt stress of taxonomically related taxa should
help to elucidate relevant mechanisms of stress tolerance in plants. We have applied this
strategy to three Plantago species adapted to different natural habitats, P. crassifolia and P.
coronopus both halophytes and P. major, considered as salt-sensitive since it is never
found in natural saline habitats. Growth inhibition measurements in controlled salt treatments
indicated, however, that P. major is quite resistant to salt stress, although less than
its halophytic congeners. The contents of monovalent ions and specific osmolytes were
determined in plant leaves after four-week salt treatments. Salt-treated plants of the three
taxa accumulated Na+ and Cl- in response to increasing external NaCl concentrations, to a
lesser extent in P. major than in the halophytes; the latter species also showed higher ion
contents in the non-stressed plants. In the halophytes, K+ concentration decreased at moderate
salinity levels, to increase again under high salt conditions, whereas in P. major K+
contents were reduced only above 400 mM NaCl. Sorbitol contents augmented in all plants,
roughly in parallel with increasing salinity, but the relative increments and the absolute values
reached did not differ much in the three taxa. On the contrary, a strong (relative) accumulation
of proline in response to high salt concentrations (600 800 mM NaCl) was
observed in the halophytes, but not in P. major. These results indicate that the responses to
salt stress triggered specifically in the halophytes, and therefore the most relevant for tolerance
in the genus Plantago are: a higher efficiency in the transport of toxic ions to the
leaves, the capacity to use inorganic ions as osmotica, even under low salinity conditions,
and the activation, in response to very high salt concentrations, of proline accumulation and
K+ transport to the leaves of the plants.MAH was a recipient of an Erasmus Mundus pre-doctoral scholarship financed by the European Commission (Welcome Consortium). AP acknowledges the Erasmus mobility programme for funding her stay in Valencia to carry out her Master Thesis.Al Hassan, M.; Pacurar, AM.; LĂłpez Gresa, MP.; Donat Torres, MDP.; Llinares Palacios, JV.; Boscaiu Neagu, MT.; Vicente Meana, Ă“. (2016). Effects of Salt Stress on Three Ecologically Distinct Plantago Species. PLoS ONE. 11(8):1-21. doi:10.1371/journal.pone.0160236S12111
Is silicon a panacea for alleviating drought and salt stress in crops?
Salinity affects around 20% of all arable land while an even larger area suffers from recurrent drought. Together these stresses suppress global crop production by as much as 50% and their impacts are predicted to be exacerbated by climate change. Infrastructure and management practices can mitigate these detrimental impacts, but are costly. Crop breeding for improved tolerance has had some success but is progressing slowly and is not keeping pace with climate change. In contrast, Silicon (Si) is known to improve plant tolerance to a range of stresses and could provide a sustainable, rapid and cost-effective mitigation method. The exact mechanisms are still under debate but it appears Si can relieve salt stress via accumulation in the root apoplast where it reduces “bypass flow of ions to the shoot. Si-dependent drought relief has been linked to lowered root hydraulic conductance and reduction of water loss through transpiration. However, many alternative mechanisms may play a role such as altered gene expression and increased accumulation of compatible solutes. Oxidative damage that occurs under stress conditions can be reduced by Si through increased antioxidative enzymes while Si-improved photosynthesis has also been reported. Si fertilizer can be produced relatively cheaply and to assess its economic viability to improve crop stress tolerance we present a cost-benefit analysis. It suggests that Si fertilization may be beneficial in many agronomic settings but may be beyond the means of smallholder farmers in developing countries. Si application may also have disadvantages, such as increased soil pH, less efficient conversion of crops into biofuel and reduced digestibility of animal fodder. These issues may hamper uptake of Si fertilization as a routine agronomic practice. Here, we critically evaluate recent literature, quantifying the most significant physiological changes associated with Si in plants under drought and salinity stress. Analyses show that metrics associated with photosynthesis, water balance and oxidative stress all improve when Si is present during plant exposure to salinity and drought. We further conclude that most of these changes can be explained by apoplastic roles of Si while there is as yet little evidence to support biochemical roles of this element
Effects of salinity and drought on growth, ionic relations, compatible solutes and activation of antioxidant systems in oleander (Nerium oleander L.)
[EN] Nerium
oleander
is an
ornamental
species
of high
aesthetic
value,
grown
in arid
and
semi-
arid
regions
because
of its
drought
tolerance,
which
is also
considered
as
relatively
resistant
to salt;
yet
the
biochemical
and
molecular
mechanisms
underlying
oleanderÂżs
stress
toler-
ance
remain
largely
unknown.
To
investigate
these
mechanisms,
one-year-old
oleander
seedlings
were
exposed
to 15
and
30
days
of treatment
with
increasing
salt
concentratio
ns,
up
to 800
mM
NaCl,
and
to complete
withholding
of irrigation;
growth
parameters
and
bio-
chemical
markers
characteristic
of conserved
stress-response
pathways
were
then
deter-
mined
in stressed
and
control
plants.
Strong
water
deficit
and
salt
stress
both
caused
inhibition
of growth,
degradation
of photosynthetic
pigments,
a slight
(but
statistically
signifi-
cant)
increase
in the
leaf
levels
of specific
osmolytes,
and
induction
of oxidative
stressÂżas
indicated
by
the
accumulation
of malondialdehyde
(MDA),
a reliable
oxidative
stress
marker
Âżaccompanied
by
increases
in the
levels
of total
phenolic
compounds
and
antioxidant
fla-
vonoids
and
in the
specific
activities
of ascorbate
peroxidase
(APX)
and
glutathione
reduc-
tase
(GR).
High
salinity,
in addition,
induced
accumulation
of Na
+
and
Cl
-
in roots
and
leaves
and
the
activation
of superoxide
dismutase
(SOD)
and
catalase
(CAT)
activities.
Apart
from
anatomical
adaptations
that
protect
oleander
from
leaf
dehydration
at moderate
levels
of
stress,
our
results
indicate
that
tolerance
of this
species
to salinity
and
water
deficit
is based
on
the
constitutive
accumulation
in leaves
of high
concentratio
ns
of soluble
carbohydrates
and,
to a lesser
extent,
of glycine
betaine,
and
in the
activation
of the
aforementioned
antiox-
idant
systems.
Moreover,
regarding
specifically
salt
stress,
mechanisms
efficiently
blocking
transport
of toxic
ions
from
the
roots
to the
aerial
parts
of the
plant
appear
to contribute
to a
large
extent
to tolerance
in
Nerium
oleanderThis work was financed by internal funds of the Polytechnic University of Valencia to Monica Boscaiu and Oscar Vicente. Dinesh Kumar’s stay in Valencia was financed by a NAMASTE fellowship from the European Union, and Mohamad Al Hassan was a recipient of an Erasmus Mundus pre-doctoral scholarship financed by the European Commission (Welcome Consortium).Kumar, D.; Al Hassan, M.; Naranjo Olivero, MA.; Agrawal, V.; Boscaiu, M.; Vicente, O. (2017). Effects of salinity and drought on growth, ionic relations, compatible solutes and activation of antioxidant systems in oleander (Nerium oleander L.). PLoS ONE. 12(9). doi:10.1371/journal.pone.0185017Se018501712
International Society of Sports Nutrition Position Stand: Probiotics.
Position statement: The International Society of Sports Nutrition (ISSN) provides an objective and critical review of the mechanisms and use of probiotic supplementation to optimize the health, performance, and recovery of athletes. Based on the current available literature, the conclusions of the ISSN are as follows: 1)Probiotics are live microorganisms that, when administered in adequate amounts, confer a health benefit on the host (FAO/WHO).2)Probiotic administration has been linked to a multitude of health benefits, with gut and immune health being the most researched applications.3)Despite the existence of shared, core mechanisms for probiotic function, health benefits of probiotics are strain- and dose-dependent.4)Athletes have varying gut microbiota compositions that appear to reflect the activity level of the host in comparison to sedentary people, with the differences linked primarily to the volume of exercise and amount of protein consumption. Whether differences in gut microbiota composition affect probiotic efficacy is unknown.5)The main function of the gut is to digest food and absorb nutrients. In athletic populations, certain probiotics strains can increase absorption of key nutrients such as amino acids from protein, and affect the pharmacology and physiological properties of multiple food components.6)Immune depression in athletes worsens with excessive training load, psychological stress, disturbed sleep, and environmental extremes, all of which can contribute to an increased risk of respiratory tract infections. In certain situations, including exposure to crowds, foreign travel and poor hygiene at home, and training or competition venues, athletes' exposure to pathogens may be elevated leading to increased rates of infections. Approximately 70% of the immune system is located in the gut and probiotic supplementation has been shown to promote a healthy immune response. In an athletic population, specific probiotic strains can reduce the number of episodes, severity and duration of upper respiratory tract infections.7)Intense, prolonged exercise, especially in the heat, has been shown to increase gut permeability which potentially can result in systemic toxemia. Specific probiotic strains can improve the integrity of the gut-barrier function in athletes.8)Administration of selected anti-inflammatory probiotic strains have been linked to improved recovery from muscle-damaging exercise.9)The minimal effective dose and method of administration (potency per serving, single vs. split dose, delivery form) of a specific probiotic strain depends on validation studies for this particular strain. Products that contain probiotics must include the genus, species, and strain of each live microorganism on its label as well as the total estimated quantity of each probiotic strain at the end of the product's shelf life, as measured by colony forming units (CFU) or live cells.10)Preclinical and early human research has shown potential probiotic benefits relevant to an athletic population that include improved body composition and lean body mass, normalizing age-related declines in testosterone levels, reductions in cortisol levels indicating improved responses to a physical or mental stressor, reduction of exercise-induced lactate, and increased neurotransmitter synthesis, cognition and mood. However, these potential benefits require validation in more rigorous human studies and in an athletic population
A new statistical framework for genetic pleiotropic analysis of high dimensional phenotype data
Installation, setup and use of a low cost c - band meteosat - 8 ground receiving station in Rwanda
Clinical Applications of Conebeam CTP Imaging in Cerebral Disease:A Systematic Review
BACKGROUND: Perfusion imaging with multidetector CT is integral to the evaluation of patients presenting with ischemic stroke due to large-vessel occlusion. Using conebeam CT perfusion in a direct-To-Angio approach could reduce workflow times and improve functional outcome.PURPOSE: Our aim was to provide an overview of conebeam CT techniques for quantifying cerebral perfusion, their clinical applications, and validation.DATA SOURCES: A systematic search was performed for articles published between January 2000 and October 2022 in which a conebeam CT imaging technique for quantifying cerebral perfusion in human subjects was compared against a reference technique.STUDY SELECTION: Eleven articles were retrieved describing 2 techniques: dual-phase (n = 6) and multiphase (n = 5) conebeam CTP. DATA ANALYSIS: Descriptions of the conebeam CT techniques and the correlations between them and the reference techniques were retrieved.DATA SYNTHESIS: Appraisal of the quality and risk of bias of the included studies revealed little concern about bias and applicability. Good correlations were reported for dual-phase conebeam CTP; however, the comprehensiveness of its parameter is unclear. Multiphase conebeam CTP demonstrated the potential for clinical implementation due to its ability to produce conventional stroke protocols. However, it did not consistently correlate with the reference techniques.LIMITATIONS: The heterogeneity within the available literature made it impossible to apply meta-Analysis to the data.CONCLUSIONS: The reviewed techniques show promise for clinical use. Beyond evaluating their diagnostic accuracy, future studies should address the practical challenges associated with implementing these techniques and the potential benefits for different ischemic diseases.</p
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