Reduced Susceptibility of Roots of Safflower to Phytophthora cryptogea After Prior Adaptation of Roots to Hypoxic Conditions

1994 ◽  
Vol 42 (1) ◽  
pp. 29 ◽  
Author(s):  
BJ Atwell ◽  
AD Heritage
Keyword(s):  
Carthamus Tinctorius ◽  
Solution Culture ◽  
Adaptation To Hypoxia ◽  
Aerenchyma Formation ◽  
Phytophthora Cryptogea ◽  
Hypoxic Conditions ◽  
Profound Influence ◽  
Root Aerenchyma ◽  
Phytoalexin Synthesis ◽  
Prior Adaptation

Safflower (Carthamus tinctorius L. cv. Gila) was grown in solution culture; the roots were inoculated with zoospores of Phytophthora cryptogea 28 d after sowing. The period for which roots were subjected to hypoxia prior to inoculation (5%(v/v) O2 in the gas stream) had a profound influence on the degree of hyphal damage to roots 8 d after inoculation. Roots exposed to hypoxia for 7 d prior to inoculation were not more than 20% necrotic 8 d after inoculation and the shoots were fully hydrated, presumably through sustained water transport by the root. Plants which were exposed to hypoxia for just 1 d after inoculation, on the other hand, developed almost total necrosis of the root system and the shoots wilted severely subsequent to infection. We propose that while short periods of hypoxia pre-dispose safflower roots to hyphal infection, a longer period of adaptation to hypoxia reverses this susceptibility. The mechanism for this protective effect, while not known, could reside in root aerenchyma formation, phytoalexin synthesis, or other metabolic and ultrastructual changes characteristic of roots exposed to low O2 conditions.

Promotion of aerenchyma formation in Pinusserotina seedlings by ethylene

1988 ◽  
Vol 18 (2) ◽  
pp. 276-280 ◽  
Author(s):  
M.A. Topa ◽  
K.W. McLeod
Keyword(s):  
Morphological Changes ◽  
Day Treatment ◽  
Indigo Carmine ◽  
Solution Culture ◽  
Longitudinal Diffusion ◽  
Aerenchyma Formation ◽  
Hypoxic Conditions ◽  
Parenchyma Cells ◽  
Exogenous Ethylene ◽  
Flowing Solution

The following study was designed to investigate a possible regulatory role for ethylene in aerenchyma and lenticel formation in pond pine (Pinusserotina Michx.) seedlings, a moderately flood-tolerant species. Seedlings were grown in noncirculating, continuously flowing solution culture under aerobic or hypoxic solution conditions; half the seedlings were treated with exogenous ethylene for the last 23 days of the 30-day treatment period. Ethylene stunted root growth, induced hypertrophy of stems and taproots, and initiated adventitious root and lenticel formation in aerobically grown seedlings. Histological studies indicated that taproot hypertrophy and resultant fissures were partially due to both an increase in number and radial enlargement of loosely packed parenchyma cells in the pericycle region. Exogenous ethylene also promoted the predominantly schizogenous formation of intercellular air spaces in the pericycle region of aerobically grown seedlings, enough to allow longitudinal diffusion of atmospheric O2 to submerged roots, as indicated via an indigo-carmine dye technique. Ethylene-treated seedlings grown under hypoxic conditions exhibited signs of reduced root vigour, with more pronounced taproot hypertrophy and fissuring than in the aerobic + ethylene treatment. Taproot fissures were a result of a proliferation of undifferentiated, loosely packed parenchyma cells in the pericycle region, with little continuous periderm development or evidence of a well-defined phellogen. Our results suggest that ethylene promotes those morphological changes in flooded roots that increase internal porosity, enhancing internal aeration.

scholarly journals Comparison of Serum HIF-1α Levels in Swimming Athletes Before and After Hypoxic Non-Hypoxic Exercise

2020 ◽  
Vol 21 (1) ◽  
pp. 36-39
Author(s):  
Syahrastani Syahrastani ◽  
Argantos Argantos ◽  
Siska Alicia Farma
Keyword(s):  
Aerobic Exercise ◽  
The Body ◽  
Anaerobic Exercise ◽  
Adaptation To Hypoxia ◽  
Cross Sectional ◽  
Hypoxic Conditions ◽  
Before And After ◽  
Cross Sectional Design ◽  
Age Range ◽  
Hypoxic Exercise

The situation of lack of oxygen supply to cells and tissues is often not realized by many people (hypoxia). Hypoxia can occur in various situations in life. The main effect of hypoxia is the effect on the brain, so the body will do everything it can to restore the state of homeostasis. HIF-1α protein is a marker of hypoxic conditions. HIF-1α regulates the synthesis of many genes to maintain and restore body homeostasis from hypoxia to normoxia. This study was a descriptive study with cross-sectional design. The sample of this study were six swimming athletes with a 12-19 year age range who met the inclusion and exclusion criteria. The HIF-1α protein is measured by the ELISA method. Data were analyzed statistically. The results showed higher levels of HIF-1α after anaerobic exercise than the levels of HIF-1α before and after aerobic exercise. This is greatly influenced by the intensity of the exercise carried out. This proves that cellular adaptation to hypoxia is more stable in aerobic exercise, where the body's metabolism during aerobic exercise is more stable  

scholarly journals Longitudinal Pattern of Aerenchyma Formation Using the Ti-Gompertz Model in Rice Adventitious Roots

2021 ◽  
Vol 12 ◽  
Author(s):  
Yun Chen ◽  
Guoming Li ◽  
Buhong Zhao ◽  
Yajun Zhang ◽  
Kun Liu ◽  
...  
Keyword(s):  
Adventitious Roots ◽  
Goodness Of Fit ◽  
Gompertz Model ◽  
Root Apex ◽  
Information Criterion ◽  
Ordinary Least Squares ◽  
Parameter Estimates ◽  
Aerenchyma Formation ◽  
Root Aerenchyma ◽  
Longitudinal Pattern

The longitudinal pattern of root aerenchyma formation of its relationship with the function of adventitious roots in rice remains unclear. In this study, the percentage of the aerenchyma area to the cross-sectional area (i.e., aerenchyma percentage) was fit with four non-linear models, namely, W0-Gompertz, Ti-Gompertz, logistic, and von Bertalanffy. Goodness-of-fit criteria such as the R2, the Akaike information criterion (AIC), and the Bayesian information criterion (BIC) were used to select the model. The bias of the parameters was evaluated using the difference between the ordinary least squares-based parameter estimates and the mean of 1,000 bootstrap-based parameter estimates and the symmetry of the distributions of these parameters. The results showed that the Ti-Gompertz model, which had a high goodness-of-fit with an R2 close to 1, lower AIC and BIC values, parameter estimates close to being unbiased, and good linear approximation, provided the best fit for the longitude pattern of rice aerenchyma formation with different root lengths among the competing models. Using the second- and third-order derivatives according to the distance from the root apex, the critical points of Ti-Gompertz were calculated. The rapid stage for aerenchyma formation was from the maximum acceleration point (1.38–1.76 cm from the root apex) to the maximum deceleration point (3.13–4.19 cm from the root apex). In this stage, the aerenchyma percentage increased by 5.3–15.7% per cm, suggesting that the cortical cells tended to die rapidly for the aerenchyma formation rather than for the respiration cost during this stage. Meanwhile, the volume of the aerenchyma of the entire roots could be computed using the integral function of the Ti-Gompertz model. We proposed that the longitudinal pattern of root aerenchyma formation modeled by the Ti-Gompertz model helped to deeply understand the relationship between the anatomical traits and physiological function in rice adventitious roots.

The human HIF (hypoxia-inducible factor)-3α gene is a HIF-1 target gene and may modulate hypoxic gene induction

2009 ◽  
Vol 424 (1) ◽  
pp. 143-151 ◽  
Author(s):  
Tetsuhiro Tanaka ◽  
Michael Wiesener ◽  
Wanja Bernhardt ◽  
Kai-Uwe Eckardt ◽  
Christina Warnecke
Keyword(s):  
Target Gene ◽  
Splice Variants ◽  
Lysyl Oxidase ◽  
Hypoxia Inducible Factor ◽  
Gene Induction ◽  
Adaptation To Hypoxia ◽  
Transcriptional Level ◽  
Dependent Manner ◽  
Hypoxic Conditions ◽  
Chemical Hypoxia

HIF (hypoxia-inducible factor)-3α is the third member of the HIF transcription factor family. Whereas HIF-1α and -2α play critical roles in the cellular and systemic adaptation to hypoxia, little is known about the regulation and function of HIF-3α. At least five different splice variants may be expressed from the human HIF-3α locus that are suggested to exert primarily negative regulatory effects on hypoxic gene induction. In the present paper, we report that hypoxia induces the human HIF-3α gene at the transcriptional level in a HIF-1-dependent manner. HIF-3α2 and HIF-3α4 transcripts, the HIF-3α splice variants expressed in Caki-1 renal carcinoma cells, rapidly increased after exposure to hypoxia or chemical hypoxia mimetics. siRNA (small interfering RNA)-mediated HIF-α knockdown demonstrated that HIF-3α is a specific target gene of HIF-1α, but is not affected by HIF-2α knockdown. In contrast with HIF-1α and HIF-2α, HIF-3α is not regulated at the level of protein stability. HIF-3α protein could be detected under normoxia in the cytoplasm and nuclei, but increased under hypoxic conditions. Promoter analyses and chromatin immunoprecipitation experiments localized a functional hypoxia-responsive element 5′ to the transcriptional start of HIF-3α2. siRNA-mediated knockdown of HIF-3α increased transactivation of a HIF-driven reporter construct and mRNA expression of lysyl oxidase. Immunohistochemistry revealed an overlap of HIF-1α-positive and HIF-3α-positive areas in human renal cell carcinomas. These findings shed light on a novel aspect of HIF-3α as a HIF-1 target gene and point to a possible role as a modulator of hypoxic gene induction.

Specific features of root aerenchyma formation in Sium latifoliun L. (Apiaceae)

2016 ◽  
Vol 50 (5) ◽  
pp. 293-299 ◽  
Author(s):  
G. V. Shevchenko ◽  
V. A. Brykov ◽  
G. F. Ivanenko
Keyword(s):  
Aerenchyma Formation ◽  
Root Aerenchyma

scholarly journals Cooperative Binding of Phosphorylated DevR to Upstream Sites Is Necessary and Sufficient for Activation of the Rv3134c-devRS Operon in Mycobacterium tuberculosis: Implication in the Induction of DevR Target Genes

2008 ◽  
Vol 190 (12) ◽  
pp. 4301-4312 ◽  
Author(s):  
Santosh Chauhan ◽  
Jaya Sivaswami Tyagi
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Target Genes ◽  
Latent Tuberculosis ◽  
Adaptation To Hypoxia ◽  
Two Component System ◽  
Promoter Regions ◽  
Hypoxic Conditions ◽  
Dnase I Footprinting ◽  
Proximal Site ◽  
Necessary And Sufficient

ABSTRACT The DevR-DevS two-component system of Mycobacterium tuberculosis mediates bacterial adaptation to hypoxia, a condition believed to be associated with the initiation and maintenance of dormant bacilli during latent tuberculosis. The activity of the Rv3134c-devRS operon was studied in M. tuberculosis using several transcriptional fusions comprised of promoter regions and the gfp reporter gene under inducing and aerobic conditions. Aerobic transcription was DevR independent, while hypoxic induction was completely DevR dependent. The hypoxia transcriptional start point, TH, was mapped at −40 bp upstream of Rv3134c. In contrast, the divergently transcribed Rv3135 gene was not induced under hypoxic conditions. DNase I footprinting and mutational analyses demonstrated that induction required the interaction of DevR∼P with binding sites centered at bp −42.5 and −63.5 relative to TH. Binding to the distal site (D) was necessary to recruit another molecule of DevR∼P to the proximal site (P), and interaction with both sequences was essential for promoter activation. These sites did not bind to either unphosphorylated or phosphorylation-defective DevR protein, which was consistent with an essential role for DevR∼P in activation. Phosphorylated DevR also bound to three copies of the motif at the hspX promoter. The Rv3134c and hspX promoters have a similar architecture, wherein the proximal DevR∼P binding site overlaps with the promoter −35 element. A model for the likely mode of action of DevR at these promoters is discussed.

Hypoxia micromanages glioma

2016 ◽  
Vol 9 (411) ◽  
pp. ec11-ec11
Author(s):  
Leslie K. Ferrarelli
Keyword(s):  
Mirna Biogenesis ◽  
Adaptation To Hypoxia ◽  
Hypoxic Conditions ◽  
Poor Patient ◽  
Glioma Initiating Cells ◽  
Expression Of Genes ◽  
Multiple Processes ◽  
Functional Blocking ◽  
Mirna Biogenesis Pathway ◽  
Poor Patient Survival

Glioblastoma (GBM) is an aggressive brain cancer that is often characterized by a hypoxic microenvironment. Hypoxia-inducible factors (HIFs) transcriptionally promote multiple processes associated with GBM progression. Hu et al. found that hypoxia-induced HIF1α in GBM increased the production of a microRNA (miRNA) that drove the proliferation of glioma-initiating cells (GICs), a subpopulation of cells that may promote the growth and recurrence of GBM. The abundance of various miRNAs was increased by hypoxia, but only the functional blocking of miR-215 decreased the proliferation of cultured patient tumor–derived GICs in intracranial xenografts in mice. The amount of mature miR-215 and pre-miR-215, but not that of pri-miR-215, was increased in GICs cultured under hypoxic conditions, suggesting that the production of miR-215 was enhanced at a posttranscriptional step in the miRNA biogenesis pathway. However, the abundance of the Drosha and Dicer complexes that mediate this step was not increased by hypoxia. HIF1α, the abundance of which was increased in hypoxic GICs, interacted with the Drosha complex on pri-miR-215, and silencing HIF1α prevented the hypoxia-induced increase in the amount of miR-215 in GICs. Microarray and reporter analyses in GICs revealed that miR-215 targets and silences the mRNA encoding the histone demethylase KDM1B. Knocking down KDM1B in GICs increased neurosphere formation and the expression of genes associated with glucose metabolism in GIC cultures, and endothelial cells cultured in medium conditioned by KDM1B-deficient GICs exhibited increased migration. Decreased abundance of KDM1B in GBM patient tumors correlated with increased expression of HIF1A and miR-215 and with poor patient survival. The findings identify a miRNA biogenesis-targeted pathway through which hypoxia promotes GBM growth.J. Hu, T. Sun, H. Wang, Z. Chen, S. Wang, L. Yuan, T. Liu, H.-R. Li, P. Wang, Y. Feng, Q. Wang, R. E. McLendon, A. H. Friedman, S. T. Keir, D. D. Bigner, J. Rathmell, X.-d. Fu, Q.-J. Li, H. Wang, X.-F. Wang, MiR-215 is induced post-transcriptionally via HIF-Drosha complex and mediates glioma-initiating cell adaptation to hypoxia by targeting KDM1B. Cancer Cell 29, 49–60 (2016). [PubMed]

scholarly journals The influence of altitude hypoxia on uroflowmetry parameters in women

2016 ◽  
Vol 311 (3) ◽  
pp. F562-F566 ◽  
Author(s):  
Vittore Verratti ◽  
Luana Paulesu ◽  
Tiziana Pietrangelo ◽  
Christian Doria ◽  
Camillo Di Giulio ◽  
...  
Keyword(s):  
Scientific Evidence ◽  
Flow Time ◽  
Adaptation To Hypoxia ◽  
Adult Women ◽  
Flow Volume ◽  
Altitude Hypoxia ◽  
Hypoxic Conditions ◽  
Time Flow ◽  
New Strategies

There is scientific evidence to suggest a correlation between hypoxia and the physiology of micturition. During a Himalayan Scientific and Mountaineering Expedition, we performed tests to investigate the functional interactions between altitude hypoxia and uroflowmetry parameters in women. The tests were carried out in seven women (36.3 ± 7.1 yr) from normoxic [1,340 meters above sea level (m a.s.l.)] to hypoxic conditions (up to 5,050 m a.s.l.) and during the return descent. The following measures were determined: uroflowmetry parameters and saturation of peripheral oxygen (SpO2). As expected, SpO2 decreased from 97.7 to 77.8% with increasing altitude. Micturition flow time, flow volume, and voiding time increased with altitude ( P < 0.04 for all), indicating a negative correlation with SpO2. In conclusion, in young adult women, micturition physiological parameters were affected during adaptation to hypoxia; the correlation with SpO2 strongly suggests a role of hypoxia in these changes. These data could help to support the design of new strategies for both prevention and medical treatment. An example of the latter might be hyperbaric oxygen therapy, which in some studies has proved able to reduce the symptoms in patients with hypoxic bladder.

Sign in / Sign up

Export Citation Format

Share Document