Drought stress negatively affects plant growth and productivity. Plants sense soil drought at the root level but the underlying mechanisms remain unclear. At the cell level, we aim to reveal the ...short-term root perception of drought stress through membrane dynamics.
In our study, 15 Medicago truncatula accessions were exposed to a polyethylene glycol (PEG)-induced drought stress, leading to contrasted ecophysiological responses, in particular related to root architecture plasticity. In the reference accession Jemalong A17, identified as drought susceptible, we analyzed lateral roots by imaging of membrane-localized fluorescent probes using confocal microscopy. We found that PEG stimulated endocytosis especially in cells belonging to the growth differentiation zone (GDZ). The mapping of membrane lipid order in cells along the root apex showed that membranes of root cap cells were more ordered than those of more differentiated cells. Moreover, PEG triggered a significant increase in membrane lipid order of rhizodermal cells from the GDZ. We initiated the membrane analysis in the drought resistant accession HM298, which did not reveal such membrane modifications in response to PEG.
Our data demonstrated that the plasma membranes of root cells from a susceptible genotype perceived drought stress by modulating their physical state both via a stimulation of endocytosis and a modification of the degree of lipid order, which could be proposed as mechanisms required for signal transduction.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
As drought is increasingly frequent in the context of climate change it is a major constraint for crop growth and yield. The ability of plants to maintain their yield in response to drought depends ...not only on their ability to tolerate drought, but also on their capacity to subsequently recover. Post-stress recovery can indeed be decisive for drought resilience and yield stability. Pea (
), as a legume, has the capacity to fix atmospheric nitrogen through its symbiotic interaction with soil bacteria within root nodules. Biological nitrogen fixation is highly sensitive to drought which can impact plant nitrogen nutrition and growth. Our study aimed at dynamically evaluating whether the control of plant N status after drought could affect nodulated pea plant's ability to recover. Two pea genotypes, Puget and Kayanne, displaying different drought resilience abilities were compared for their capacity to tolerate to, and to recover from, a 2-weeks water-deficit period applied before flowering. Physiological processes were studied in this time-series experiment using a conceptual structure-function analysis framework focusing on whole plant carbon, nitrogen, and water fluxes combined to two
CO
and
N
labeling experiments. While Puget showed a yield decrease compared to well-watered plants, Kayanne was able to maintain its yield. During the recovery period, genotype-dependent strategies were observed. The analysis of the synchronization of carbon, nitrogen, and water related traits dynamics during the recovery period and at the whole plant level, revealed that plant growth recovery was tightly linked to N nutrition. In Puget, the initiation of new nodules after water deficit was delayed compared to control plants, and additional nodules developed, while in Kayanne the formation of nodules was both rapidly and strictly re-adjusted to plant growth needs, allowing a full recovery. Our study suggested that a rapid re-launch of N acquisition, associated with a fine-tuning of nodule formation during the post-stress period is essential for efficient drought resilience in pea leading to yield stability.
Peas, as legume crops, could play a major role in the future of food security in the context of worldwide human nutrient deficiencies coupled with the growing need to reduce consumption of animal ...products. However, pea yields, in terms of quantity and quality (i.e. grain content), are both susceptible to climate change, and more specifically to water deficits, which nowadays occur more frequently during crop growth cycles and tend to last longer. The impact of soil water stress on plant development and plant growth is complex, as its impact varies depending on soil water availability (through the modulation of elements available in the soil), and by the plant's ability to acclimate to continuous stress or to memorize previous stress events.
To identify the strategies underlying these plant responses to water stress events, pea plants were grown in controlled conditions under optimal water treatment and different types of water stress; transient (during vegetative or reproductive periods), recurrent, and continuous (throughout the plant growth cycle). Traits related to water, carbon, and ionome uptake and uses were measured and allowed the identification typical plant strategies to cope with water stress.
Our results highlighted (i) the common responses to the three types of water stress in shoots, involving manganese (Mn) in particular, (ii) the potential implications of boron (B) for root architecture modification under continuous stress, and (iii) the establishment of an "ecophysiological imprint" in the root system
an increase in nodule numbers during the recovery period.
AIMS: The aims of this work were (1) to analyze concomitantly both structural and functional responses of pea plants subjected to decreasing water availability and (2) to evaluate their ability to ...recover after the drought period. METHODS: A pot experiment compared the growth and the nitrogen nutrition of pea plants exposed, during their vegetative stage, to seven water availability levels. RESULTS: Our results showed that the plant first reacted to water deprivation by maintaining root growth during drought and secondly to a nitrogen deficiency by allocating more carbon to the nodules responsible for nitrogen acquisition during recovery. The specific activity of nodules was negatively impacted by water stress during drought, fully recovered afterwards except after a severe water stress and the number of nodules initiated during recovery depended on the nitrogen nutritional index of the plant at the end of the drought period. This strategy allowed the plant to recover sufficiently and to maintain high values of yield components at harvest, except after a severe water stress, which reduced seed number. CONCLUSION: Our findings revealed that water availability levels did not change plant strategy in response to drought but increased the responses observed.
The cultivation of legumes shows promise for the development of sustainable agriculture, but yield instability remains one of the main obstacles for its adoption. Here, we tested whether the yield ...stability (i.e., resistance and resilience) of pea plants subjected to drought could be enhanced by soil microbial diversity. We used a dilution approach to manipulate the microbial diversity, with a genotype approach to distinguish the effect of symbionts from that of microbial diversity as a whole. We investigated the physiology of plants in response to drought when grown on a soil containing high or low level of microbial diversity. Plants grown under high microbial diversity displayed higher productivity and greater resilience after drought. Yield losses were mitigated by 15% on average in the presence of high soil microbial diversity at sowing. Our study provides proof of concept that the soil microbial community as a whole plays a key role for yield stability after drought even in plant species living in relationships with microbial symbionts. These results emphasize the need to restore soil biodiversity for sustainable crop management and climate change adaptation.
Plants grown under high microbial diversity display higher productivity and better resilience after drought. We provide proof of concept that the soil microbial community as a whole plays a key role in plant stability under drought even in plant species supporting microbial symbiotic relationships.
Introduction Peas, as legume crops, could play a major role in the future of food security in the context of worldwide human nutrient deficiencies coupled with the growing need to reduce consumption ...of animal products. However, pea yields, in terms of quantity and quality (i.e. grain content), are both susceptible to climate change, and more specifically to water deficits, which nowadays occur more frequently during crop growth cycles and tend to last longer. The impact of soil water stress on plant development and plant growth is complex, as its impact varies depending on soil water availability (through the modulation of elements available in the soil), and by the plant’s ability to acclimate to continuous stress or to memorize previous stress events. Method To identify the strategies underlying these plant responses to water stress events, pea plants were grown in controlled conditions under optimal water treatment and different types of water stress; transient (during vegetative or reproductive periods), recurrent, and continuous (throughout the plant growth cycle). Traits related to water, carbon, and ionome uptake and uses were measured and allowed the identification typical plant strategies to cope with water stress. Conclusion Our results highlighted (i) the common responses to the three types of water stress in shoots, involving manganese (Mn) in particular, (ii) the potential implications of boron (B) for root architecture modification under continuous stress, and (iii) the establishment of an “ecophysiological imprint” in the root system via an increase in nodule numbers during the recovery period.
The addition of cetuximab (CTX) to the combination of cisplatin and 5-fluorouracil increases the overall survival (OS) in recurrent/metastatic head and neck squamous cell carcinoma. Only a few ...patients are eligible for this treatment because of its toxicity. The combination of CTX and paclitaxel (TXL) could be included in sequential treatment strategies. Patients were treated with CTX (400/250 mg/m) and TXL (60–80 mg/m) weekly until disease progression or unacceptable toxicity. Efficacy and safety outcomes were determined retrospectively. A total of 42 patients were included in this analysis. The overall response rate was 38% 95% confidence interval (CI); 23–53%. The disease control rate with TXL and CTX combination was 74%. Seven (17%) patients progressed before the first evaluation. The median progression-free survival was 3.9 months 95% CI; 3.1–4.7 months and the median OS was 7.6 months 95% CI; 5.3–9.9 months. Neurotoxicity and skin rash were the most frequent grade≥2 toxicities, reported in 17 and 12% of patients, respectively. Previous chemotherapy seems to be associated with a lower response rate and progression-free survival but not with the OS. The combination of CTX and TXL was an active and well-tolerated treatment in this series of patients with a poor prognosis and who were mostly symptomatic.
Novel biomarkers related to main clinical hallmarks of Chronic obstructive pulmonary disease (COPD), a heterogeneous disorder with pulmonary and extra-pulmonary manifestations, were investigated by ...profiling the serum levels of 1305 proteins using Slow Off-rate Modified Aptamers (SOMA)scan technology.
Serum samples were collected from 241 COPD subjects in the multicenter French Cohort of Bronchial obstruction and Asthma to measure the expression of 1305 proteins using SOMAscan proteomic platform. Clustering of the proteomics was applied to identify disease subtypes and their functional annotation and association with key clinical parameters were examined. Cluster findings were revalidated during a follow-up visit, and compared to those obtained in a group of 47 COPD patients included in the Melbourne Longitudinal COPD Cohort.
Unsupervised clustering identified two clusters within COPD subjects at inclusion. Cluster 1 showed elevated levels of factors contributing to tissue injury, whereas Cluster 2 had higher expression of proteins associated with enhanced immunity and host defense, cell fate, remodeling and repair and altered metabolism/mitochondrial functions. Patients in Cluster 2 had a lower incidence of exacerbations, unscheduled medical visits and prevalence of emphysema and diabetes. These protein expression patterns were conserved during a follow-up second visit, and substanciated, by a large part, in a limited series of COPD patients. Further analyses identified a signature of 15 proteins that accurately differentiated the two COPD clusters at the 2 visits.
This study provides insights into COPD heterogeneity and suggests that overexpression of factors involved in lung immunity/host defense, cell fate/repair/ remodelling and mitochondrial/metabolic activities contribute to better clinical outcomes. Hence, high throughput proteomic assay offers a powerful tool for identifying COPD endotypes and facilitating targeted therapies.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The combination platinum, 5-fluorouracil (5-FU) and cetuximab is the standard first-line regimen of recurrent and/or metastatic head and neck squamous cell carcinoma (HNSCC). Due to the toxicity of ...this treatment, alternative therapies are often offered to patients. The aim of this study was to evaluate the overall survival obtained with a first line chemotherapy adapted to patients functional status and the administration of all active drugs within successive lines of chemotherapy.
This series included a total of 194 patients with recurrent and/or metastatic HNSCC treated from 2006 to 2011 in a single institution where the administration of successive lines of chemotherapies has been the standard clinical approach. Treatment was administered according to clinical practice guidelines.
Most patients received at least two treatment lines. Only 11 patients (6%) were treated with a combination of cisplatin, 5-FU and cetuximab in front line, but most patients received at least one platinum-based regimen (n = 154 patients, 78%); 162 (82%) received taxanes, 36 (18%) received 5-FU, 27 (14%) received capecitabine, 67 (34%) received methotrexate and 134 (68%) received cetuximab. The median overall survival was 9.8 months (95% CI: 8.1-11.4 months) and reached 13.1 months among the subgroup of 131 patients eligible for inclusion in a clinical trial.
The survival outcomes of patients treated in the first-line setting with chemotherapy regimens adapted to their functional status, followed by several subsequent regimens were comparable with published outcomes of patients treated by platinum, 5-FU and cetuximab.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
To investigate the effect of chronic oral arginine aspartate on the growth hormone (GH), GH‐releasing hormone (GHRH), insulin‐like growth factor‐1 (IGF‐1) and IGF‐binding protein‐3 (IGFBP‐3) ...secretions in healthy volunteers. Twenty‐three healthy non‐athlete volunteer males were administered arginine aspartate (30 g) orally once daily at 21:00 h for 21 consecutive days. Subjects were hospitalized on days 0, 1, 3, 5, 7, 14 and 21 of treatment. At each hospitalization, concentrations of GHRH, GH, IGF‐1 and IGFBP‐3 were measured over 4 h after arginine aspartate intake. GH, IGF‐1 and IGFBP‐3 concentrations were also determined over 12 h at days 0, 1 and 21. Compared with day 1, 4 h GH levels dropped at day 5 and subsequently rose to levels not significantly different from initial ones. The latter was substantiated by 12 h GH levels that did not significantly change from days 1 to 21. GHRH levels were not statistically different, although there was a trend in median values that seemed to inversely mirror those of GH. This dynamic over the course of the study for GH and GHRH was accompanied by a general decrease in IGF‐1 and IGFBP‐3. In healthy volunteers, a chronic oral treatment with 30 g/day arginine aspartate is followed by a decrease in IGF‐1 and IGFBP‐3 secretions.
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