Sensitivity to hypoxia and microbial activity are instrumental in pericarp-imposed dormancy expression in sunflower (Helianthus annuus L.)

2019 ◽  
Vol 29 (2) ◽  
pp. 85-96 ◽  
Author(s):  
Constanza P. Dominguez ◽  
María V. Rodríguez ◽  
Diego Batlla ◽  
Inés E. García de Salamone ◽  
Anita I. Mantese ◽  
...  
Keyword(s):  
Microbial Activity ◽  
Incubation Temperature ◽  
Bacterial Load ◽  
Bacterial Colony ◽  
Aba Metabolism ◽  
Increased Sensitivity ◽  
Bacteria And Fungi ◽  
Incubation Temperatures ◽  
Aba Content

AbstractWe used two sunflower genotypes displaying pericarp-imposed dormancy at high incubation temperatures (i.e. 30°C) to investigate the role of the pericarp as a limitation to oxygen availability to the embryo (hypoxia), and its impact on embryo abscisic acid (ABA) content and sensitivity to ABA. Results showed that both genotypes displayed very different oxygen threshold values for inhibition of embryo germination when incubation was performed at 30°C. Expression of dormancy in one genotype was therefore related to exacerbated embryo sensitivity to hypoxia, whereas in the other genotype, the pericarp appeared to act as a more severe restraint to oxygen entry. Increased sensitivity to hypoxia was, in part, related to increased sensitivity to ABA, but not to alterations in ABA metabolism. The activity of pericarp-microbial communities (bacteria and fungi) at high temperatures was also assessed as a potential determinant of hypoxia to the embryo. Oxygen consumption in pericarps incubated at 30°C was attenuated with antibiotics, which concomitantly promoted achene germination. In agreement with the observed more severe oxygen deprivation to the embryo exerted by the pericarp, the bacterial load in the pericarp was significantly higher in the commercial hybrid than in the inbred line; however, the application of antibiotics strongly reduced the bacterial colony counts for each genotype. Different bacterial and fungal communities, assessed through their profiles of carbon-source utilization, were determined between genotypes and after treatment with antibiotics. This work highlights the relationship between enhancement of sensitivity to hypoxia with incubation temperature and seed dormancy expression, and suggests that microbial activity might be part of the mechanism through which hypoxia is imposed.

Progress in research on dry afterripening

2011 ◽  
Vol 21 (2) ◽  
pp. 69-80 ◽  
Author(s):  
Raquel Iglesias-Fernández ◽  
María del Carmen Rodríguez-Gacio ◽  
Angel J. Matilla
Keyword(s):  
Reactive Oxygen Species ◽  
Reactive Oxygen ◽  
Storage Conditions ◽  
Oxygen Species ◽  
Dormancy Breaking ◽  
Aba Metabolism ◽  
Signalling Network ◽  
Increased Sensitivity ◽  
Temperature Window

AbstractThe transition from the dormant to the non-dormant state of a viable and mature seed can take place at low hydration by exposure to air-dry storage conditions (dry afterripening; AR). The events occurring during this loss of dormancy are of considerable physiological, ecological and agricultural interest. AR may be attributable to increased sensitivity to germination-stimulating factors and a widening of the temperature window for germination. Genetic, –omics and physiological studies on this mode of dormancy breaking provide support for a key role of the balance between gibberellin (GA) and abscisic acid (ABA) metabolism and sensitivity. Recent evidence also supports a possible role for ethylene (ET) in this complex signalling network that is necessary for AR implementation. However, hormone-independent signals, such as reactive oxygen species (ROS), nitrate (NO _{3}^{ - } ) or nicotinamide adenine dinucleotide (NAD+), also appear to be involved. The way in which hormone- and non-hormone-signalling pathways affects each other (cross-talk) is still under study. This review provides updated information on the programmes that overcome seed dormancy. Thus, we have reviewed: (1) the –omic status in dry seeds; (2) the relationship between temperature and nitrate signalling and AR; (3) alterations in ABA/GA synthesis and signalling; (4) the action of hormone molecules other than ABA and GA (i.e. ET, salicylic and jasmonic acids); and (5) participation of reactive oxygen species (ROS), NAD+ and protein carbonylation. Taken together, the acquisition and implementation of dry AR involve a complex signalling network that is difficult to disentangle.

Evaluation and use of a low nutrient medium and reduced incubation temperature to study bacterial contamination in the water supply of dental units

1994 ◽  
Vol 40 (2) ◽  
pp. 127-131 ◽  
Author(s):  
H. N. Williams ◽  
H. Quinby ◽  
E. Romberg
Keyword(s):  
Water Supply ◽  
Nutrient Medium ◽  
Bacterial Contamination ◽  
Bacterial Population ◽  
Incubation Temperature ◽  
Stagnant Water ◽  
Bacterial Colony ◽  
Colony Forming Units ◽  
Peptone Medium ◽  
Incubation Temperatures

A low nutrient medium, dilute peptone, and reduced incubation temperatures (25 or 30 °C) were used to recover bacteria from dental unit water supply. Significantly greater numbers of bacterial colony-forming units were recovered on the dilute peptone medium than on the enriched media, blood agar or trypticase soy agar. Lower incubation temperatures yielded greater numbers of colony-forming units on all media. The bacterial population in dental unit water supply following stagnation in the supply lines and flushing of the lines was studied using dilute peptone incubated at 25 °C. No significant differences in the numbers of colony-forming units were found in stagnant water versus fresh water. Flushing the water lines for 10 min did not significantly reduce the numbers of colony-forming units.Key words: dental unit water, water contamination, bacterial contamination.

scholarly journals Role of Commensal Microbes in the γ-Ray Irradiation-Induced Physiological Changes in Drosophila melanogaster

2020 ◽  
Vol 9 (1) ◽  
pp. 31
Author(s):  
Hwa-Jin Lee ◽  
Shin-Hae Lee ◽  
Ji-Hyeon Lee ◽  
Yongjoong Kim ◽  
Ki Moon Seong ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Bacterial Load ◽  
Physiological Changes ◽  
Operational Taxonomic Units ◽  
Increased Sensitivity ◽  
Γ Ray ◽  
Significant Change ◽  
The Relationship ◽  
Locomotion Activity

Ionizing radiation induces biological/physiological changes and affects commensal microbes, but few studies have examined the relationship between the physiological changes induced by irradiation and commensal microbes. This study investigated the role of commensal microbes in the γ-ray irradiation-induced physiological changes in Drosophila melanogaster. The bacterial load was increased in 5 Gy irradiated flies, but irradiation decreased the number of operational taxonomic units. The mean lifespan of conventional flies showed no significant change by irradiation, whereas that of axenic flies was negatively correlated with the radiation dose. γ-Ray irradiation did not change the average number of eggs in both conventional and axenic flies. Locomotion of conventional flies was decreased after 5 Gy radiation exposure, whereas no significant change in locomotion activity was detected in axenic flies after irradiation. γ-Ray irradiation increased the generation of reactive oxygen species in both conventional and axenic flies, but the increase was higher in axenic flies. Similarly, the amounts of mitochondria were increased in irradiated axenic flies but not in conventional flies. These results suggest that axenic flies are more sensitive in their mitochondrial responses to radiation than conventional flies, and increased sensitivity leads to a reduced lifespan and other physiological changes in axenic flies.

Abscisic acid and the control of seed dormancy and germination

2010 ◽  
Vol 20 (2) ◽  
pp. 55-67 ◽  
Author(s):  
Eiji Nambara ◽  
Masanori Okamoto ◽  
Kiyoshi Tatematsu ◽  
Ryoichi Yano ◽  
Mitsunori Seo ◽  
...  
Keyword(s):  
Abscisic Acid ◽  
High Temperature ◽  
Seed Dormancy ◽  
Plant Hormone ◽  
The Core ◽  
Aba Metabolism ◽  
External Cues ◽  
Aba Content ◽  
Seed Dormancy And Germination

AbstractAbscisic acid (ABA) is a plant hormone that regulates seed dormancy and germination. Seeds undergo changes in both ABA content and sensitivity during seed development and germination in response to internal and external cues. Recent advances in functional genomics have revealed the integral components involved in ABA metabolism (biosynthesis and catabolism) and perception, the core signalling pathway, as well as the factors that trigger ABA-mediated transcription. These allow for comparative studies to be conducted on seeds under different environmental conditions and from different genetic backgrounds. This review summarizes our understanding of the control of ABA content and the responsiveness of seeds to afterripening, light, high temperature and nitrate, with a focus on which tissues are involved in its metabolism and signalling. Also described are the regulators of ABA metabolism and signalling, which potentially act as the node for hormone crosstalk. Integration of such knowledge into the complex and diverse events occurring during seed germination will be the next challenge, which will allow for a clearer understanding of the role of ABA.

scholarly journals An R2R3-type myeloblastosis transcription factor MYB103 is involved in phosphorus remobilization

2020 ◽  
Vol 2 (1) ◽  
Author(s):  
Fangwei Yu ◽  
Shenyun Wang ◽  
Wei Zhang ◽  
Hong Wang ◽  
Li Yu ◽  
...  
Keyword(s):  
Cell Wall ◽  
Transcription Factor ◽  
Abiotic Stresses ◽  
Myb Transcription Factor ◽  
Ethylene Signaling ◽  
Biotic And Abiotic Stresses ◽  
P Deficiency ◽  
P Concentration ◽  
Increased Sensitivity

Abstract The members of myeloblastosis transcription factor (MYB TF) family are involved in the regulation of biotic and abiotic stresses in plants. However, the role of MYB TF in phosphorus remobilization remains largely unexplored. In the present study, we show that an R2R3 type MYB transcription factor, MYB103, is involved in phosphorus (P) remobilization. MYB103 was remarkably induced by P deficiency in cabbage (Brassica oleracea var. capitata L.). As cabbage lacks the proper mutant for elucidating the mechanism of MYB103 in P deficiency, another member of the crucifer family, Arabidopsis thaliana was chosen for further study. The transcript of its homologue AtMYB103 was also elevated in response to P deficiency in A. thaliana, while disruption of AtMYB103 (myb103) exhibited increased sensitivity to P deficiency, accompanied with decreased tissue biomass and soluble P concentration. Furthermore, AtMYB103 was involved in the P reutilization from cell wall, as less P was released from the cell wall in myb103 than in wildtype, coinciding with the reduction of ethylene production. Taken together, our results uncover an important role of MYB103 in the P remobilization, presumably through ethylene signaling.

Phytotoxic Effect of Decaying Quackgrass (Agropyron repens) Residues

Weed Science ◽  
1979 ◽  
Vol 27 (6) ◽  
pp. 595-598 ◽  
Author(s):  
T. V. Toai ◽  
D. L. Linscott
Keyword(s):  
Incubation Temperature ◽  
Soil Surface ◽  
Water Soluble ◽  
Water Extracts ◽  
Phytotoxic Activity ◽  
Phytotoxic Effect ◽  
Effects Of Temperature ◽  
Incubation Temperatures ◽  
Toxin Formation ◽  
Agropyron Repens

We studied the effects of temperature (5, 10, 20, and 30 C) on the phytotoxic activity of decaying quackgrass [Agropyron repens (L.) Beauv.] leaves and rhizomes that were incubated in soils for 0, 1, 2, 4, and 6 weeks. Alfalfa (Medicago sativa L.) seeds were grown for 96 h in water, water extracts of control soils, and water extracts of soil with quackgrass rhizomes or leaves. Dried quackgrass rhizomes and leaves contained water-soluble toxins that inhibited alfalfa seedling development and growth. There was a strong interaction between incubation time and temperature on the development of additional toxins by decomposing quackgrass. High incubation temperature (30 C) accelerated toxin formation and ultimate decay. Intermediate temperature (20 C) delayed toxin formation and decay. Low incubation temperatures (5 C and 10 C) prevented formation of additional toxin. In all extracts of quackgrass and soil that had been incubated for 6 weeks, normal alfalfa seedling number equaled that in water. However, seedling growth varied with incubation temperatures.Treatment of quackgrass with glyphosate [N-(phosphonomethyl) glycine] in the greenhouse did not influence the toxicity of decaying quackgrass leaves. The highest toxic effect was noted after 1 week of decay on the soil surface.

scholarly journals Ref2, a regulatory subunit of the yeast protein phosphatase 1, is a novel component of cation homoeostasis

2010 ◽  
Vol 426 (3) ◽  
pp. 355-364 ◽  
Author(s):  
Jofre Ferrer-Dalmau ◽  
Asier González ◽  
Maria Platara ◽  
Clara Navarrete ◽  
José L. Martínez ◽  
...  
Keyword(s):  
Protein Phosphatase ◽  
Living Organism ◽  
Calcium Sensitivity ◽  
Growth Conditions ◽  
Protein Phosphatase 1 ◽  
Regulatory Subunit ◽  
Alkaline Ph ◽  
Yeast Protein ◽  
Increased Sensitivity

Maintenance of cation homoeostasis is a key process for any living organism. Specific mutations in Glc7, the essential catalytic subunit of yeast protein phosphatase 1, result in salt and alkaline pH sensitivity, suggesting a role for this protein in cation homoeostasis. We screened a collection of Glc7 regulatory subunit mutants for altered tolerance to diverse cations (sodium, lithium and calcium) and alkaline pH. Among 18 candidates, only deletion of REF2 (RNA end formation 2) yielded increased sensitivity to these conditions, as well as to diverse organic toxic cations. The Ref2F374A mutation, which renders it unable to bind Glc7, did not rescue the salt-related phenotypes of the ref2 strain, suggesting that Ref2 function in cation homoeostasis is mediated by Glc7. The ref2 deletion mutant displays a marked decrease in lithium efflux, which can be explained by the inability of these cells to fully induce the Na+-ATPase ENA1 gene. The effect of lack of Ref2 is additive to that of blockage of the calcineurin pathway and might disrupt multiple mechanisms controlling ENA1 expression. ref2 cells display a striking defect in vacuolar morphogenesis, which probably accounts for the increased calcium levels observed under standard growth conditions and the strong calcium sensitivity of this mutant. Remarkably, the evidence collected indicates that the role of Ref2 in cation homoeostasis may be unrelated to its previously identified function in the formation of mRNA via the APT (for associated with Pta1) complex.

scholarly journals TLR4-dependent GM-CSF protects against lung injury in Gram-negative bacterial pneumonia

2012 ◽  
Vol 302 (5) ◽  
pp. L447-L454 ◽  
Author(s):  
Louis R. Standiford ◽  
Theodore J. Standiford ◽  
Michael J. Newstead ◽  
Xianying Zeng ◽  
Megan N. Ballinger ◽  
...  
Keyword(s):  
Lung Injury ◽  
Bacterial Pneumonia ◽  
Lavage Fluid ◽  
Alveolar Epithelial Cells ◽  
Intratracheal Administration ◽  
Bacterial Colony ◽  
Gram Negative ◽  
Gm Csf

Toll-like receptors (TLRs) are required for protective host defense against bacterial pathogens. However, the role of TLRs in regulating lung injury during Gram-negative bacterial pneumonia has not been thoroughly investigated. In this study, experiments were performed to evaluate the role of TLR4 in pulmonary responses against Klebsiella pneumoniae (Kp). Compared with wild-type (WT) (Balb/c) mice, mice with defective TLR4 signaling (TLR4lps-d mice) had substantially higher lung bacterial colony-forming units after intratracheal challenge with Kp, which was associated with considerably greater lung permeability and lung cell death. Reduced expression of granulocyte-macrophage colony-stimulating factor (GM-CSF) mRNA and protein was noted in lungs and bronchoalveolar lavage fluid of TLR4 mutant mice postintratracheal Kp compared with WT mice, and primary alveolar epithelial cells (AEC) harvested from TLR4lps-d mice produced significantly less GM-CSF in vitro in response to heat-killed Kp compared with WT AEC. TLR4lps-d AEC underwent significantly more apoptosis in response to heat-killed Kp in vitro, and treatment with GM-CSF protected these cells from apoptosis in response to Kp. Finally, intratracheal administration of GM-CSF in TLR4lps-d mice significantly decreased albumin leak, lung cell apoptosis, and bacteremia in Kp-infected mice. Based on these observations, we conclude that TLR4 plays a protective role on lung epithelium during Gram-negative bacterial pneumonia, an effect that is partially mediated by GM-CSF.

scholarly journals Influence of Gelatin-Thrombin Matrix Tissue Sealant on Bacterial Colony Formation and Risk of Pelvic Infection

2016 ◽  
Vol 2016 ◽  
pp. 1-6
Author(s):  
Michael J. Jarrett ◽  
Andres Vázquez-Torres ◽  
Daniel N. Frank ◽  
Bruce D. McCollister ◽  
Patrick K. Henthorn ◽  
...  
Keyword(s):  
Colony Formation ◽  
Rrna Gene ◽  
Contributing Factors ◽  
Vaginal Cuff ◽  
Pelvic Infection ◽  
Bacterial Colony ◽  
E Coli ◽  
Tissue Sealant

Objective. Gelatin-thrombin matrix (GTM) tissue sealant use was previously identified as an independent predictor of pelvic infection following hysterectomies. We aim to elucidate contributing factors by assessing influence of GTM on bacterial colony formation and characterizing bacteria present at the vaginal cuff.Methods.Escherichia coliwas incubated in phosphate-buffered saline (PBS) and pelvic washings with and without GTM to assess influence on colony formation. Pelvic washings of the vaginal cuff were collected from hysterectomies occurring from June through October 2015.In vitrotechniques, 16S rRNA gene qPCR, and 16S amplicon sequencing were performed with washings to characterize bacteria at the vaginal cuff.Results. Mean bacterial colony formation in PBS was greater forE. coliincubated in the presence of GTM (1.48 × 107 CFU/mL) versus without (9.95 × 105 CFU/mL) following 20-hour incubation (p=0.001). Out of 61 pelvic washings samples, 3 were culture positive (≥5000 CFU/mL) withEnterococcus faecalis.Conclusion.In vitroexperiments support a facilitating role of GTM on colony formation ofE. coliin PBS. However, given the negative results of surgical site washings following adequate disinfection, the role of GTM in promoting posthysterectomy pelvic infections may be limited. Analysis of pelvic washings revealed presence ofE. faecalis, but results were inconclusive. Further studies are recommended.

Thermal and water source effects upon the stability of enteroviruses in surface freshwaters

1989 ◽  
Vol 35 (4) ◽  
pp. 474-480 ◽  
Author(s):  
Christon J. Hurst ◽  
William H. Benton ◽  
Kim A. McClellan
Keyword(s):  
Bacterial Growth ◽  
Incubation Temperature ◽  
Water Source ◽  
Inactivation Rate ◽  
Human Enterovirus ◽  
Strongly Correlated ◽  
Artificial Lake ◽  
Viral Inactivation ◽  
Term Survival ◽  
Incubation Temperatures

The long-term survival of three human enterovirus serotypes, Coxsackievirus B3, echovirus 7, and poliovirus 1 was examined in samples of surface freshwater collected from five sites of physically different character. These were an artificial lake created by damming a creek, a small groundwater outlet pond, both a large- and a medium-sized river, and a small suburban creek. Survival was studied at temperatures of −20, 1, and 22 °C. The average amount of viral inactivation was 6.50–7.0 log10 units over 8 weeks at 22 °C, 4–5 log10 units over 12 weeks at 1 °C, and 0.4–0.8 log10 units over 12 weeks at −20 °C. The effect of incubation temperature upon viral inactivation rate was statistically significant (p < 0.00001). As determined by pairing tests, survival was also significantly related to both viral serotype and water source at each of the three incubation temperatures (p ≤ 0.05). Efforts were made to determine whether the rate of viral inactivation observed at the different incubation temperatures was related to characteristics inherent to the water that was collected from the different locations. The characteristics examined included physical and chemical parameters, indigenous bacterial counts, and the amount of bacterial growth that the waters would support (measured as the maximum number of generations which seeded bacteria could undergo after being placed into either pasteurized or sterile-filtered water samples). Analysis of viral inactivation rate versus these characteristics revealed three apparent effectors of viral persistence. These were (i) hardness and conductivity, both of which strongly correlated with one another; (ii) turbidity and suspended solids content, both of which strongly correlated with one another; and (iii) the number of generations of bacterial growth that a sample was capable of supporting, which also correlated with hardness and conductivity.Key words: virus, survival, inactivation rate, water.

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