scholarly journals The Arabidopsis Diacylglycerol Kinase 4 is involved in nitric oxide-dependent pollen tube guidance and fertilization

2019 ◽  
Author(s):  
Aloysius Wong ◽  
Lara Donaldson ◽  
Maria Teresa Portes ◽  
Jörg Eppinger ◽  
José Feijó ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Pollen Tube ◽  
Cell Communication ◽  
Male Gamete ◽  
Diacylglycerol Kinase ◽  
Vascular Wall ◽  
Pollen Tube Guidance ◽  
Actin Organization ◽  
Downstream Signaling

SummaryNitric oxide (NO) is a key signaling molecule that regulates diverse biological processes in both animals and plants. In animals, NO regulates vascular wall tone, neurotransmission and immune response while in plants, NO is essential for development and responses to biotic and abiotic stresses [1–3]. Interestingly, NO is involved in the sexual reproduction of both animals and plants mediating physiological events related to the male gamete [2, 4]. In animals, NO stimulates sperm motility [4] and binding to the plasma membrane of oocytes [5] while in plants, NO mediates pollen-stigma interactions and pollen tube guidance [6, 7]. NO generation in pollen tubes (PTs) has been demonstrated [8] and intracellular responses to NO include cytosolic Ca2+ elevation, actin organization, vesicle trafficking and cell wall deposition [7, 9]. However, the NO-responsive proteins that mediate these responses are still elusive. Here we show that PTs of Arabidopsis lacking the pollen-specific Diacylglycerol Kinase 4 (DGK4) grow slower and become insensitive to NO-dependent growth inhibition and re-orientation responses. Recombinant DGK4 protein yields NO-responsive spectral and catalytic changes in vitro which are compatible with a role in NO perception and signaling in PTs. NO is a fast, diffusible gas and, based on our results, we hypothesize it could serve in long range signaling and/or rapid cell-cell communication functions mediated by DGK4 downstream signaling during the progamic phase of angiosperm reproduction.

Losartan Increases No Production from the Bovine Aortic Wall That is Stimulated by Angiotensin II

2003 ◽  
Vol 1 (3) ◽  
pp. 113-117 ◽  
Author(s):  
M. Myronidou ◽  
B. Kokkas ◽  
A. Kouyoumtzis ◽  
N. Gregoriadis ◽  
A. Lourbopoulos ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Angiotensin Ii ◽  
Aortic Wall ◽  
Vascular Wall ◽  
Protective Role ◽  
Normal Function ◽  
No Production ◽  
Chemical Inactivation

In these studies we investigated if losartan, an AT1- receptor blocker has any beneficial effect on NO production from the bovine aortic preparations in vitro while under stimulation from angiotensin II. Experiments were performed on intact specimens of bovine thoracic aorta, incubated in Dulbeco's MOD medium in a metabolic shaker for 24 hours under 95 % O2 and 5 % CO2 at a temperature of 37°C. We found that angiotensin II 1nM−10 μM does not exert any statistically significant action on NO production. On the contrary, angiotensin II 10nM increases the production of NO by 58.14 % (from 12.16 + 2.9 μm/l to 19.23 + 4.2 μm/l in the presence of losartan 1nM (P<0.05). Nitric oxide levels depend on both rate production and rate catabolism or chemical inactivation. Such an equilibrium is vital for the normal function of many systems including the cardiovascular one. The above results demonstrate that the blockade of AT1-receptors favors the biosynthesis of NO and indicate the protective role of losartan on the vascular wall.

scholarly journals Arabidopsis DIACYLGLYCEROL KINASE4 is involved in nitric oxide-dependent pollen tube guidance and fertilization

Development ◽  
2020 ◽  
Vol 147 (8) ◽  
pp. dev183715 ◽  
Author(s):  
Aloysius Wong ◽  
Lara Donaldson ◽  
Maria Teresa Portes ◽  
Jörg Eppinger ◽  
José A. Feijó ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Pollen Tube ◽  
Pollen Tube Guidance

scholarly journals Heme proteins mediate the conversion of nitrite to nitric oxide in the vascular wall

2008 ◽  
Vol 295 (2) ◽  
pp. H499-H508 ◽  
Author(s):  
Wael F. Alzawahra ◽  
M. A. Hassan Talukder ◽  
Xiaoping Liu ◽  
Alexandre Samouilov ◽  
Jay L. Zweier
Keyword(s):  
Nitric Oxide ◽  
Heme Proteins ◽  
Soluble Guanylyl Cyclase ◽  
Vascular Wall ◽  
Rat Aorta ◽  
No Production ◽  
Paramagnetic Resonance ◽  
Physiological Importance

Nitric oxide (NO) has been shown to be the endothelium-derived relaxing factor (EDRF), and its impairment contributes to a variety of cardiovascular disorders. Recently, it has been recognized that nitrite can be an important source of NO; however, questions remain regarding the activity and mechanisms of nitrite bioactivation in vessels and its physiological importance. Therefore, we investigated the effects of nitrite on in vivo hemodynamics in rats and in vitro vasorelaxation in isolated rat aorta under aerobic conditions. Studies were performed to determine the mechanisms by which nitrite is converted to NO. In anesthetized rats, nitrite dose dependently decreased both systolic and diastolic blood pressure with a threshold dose of 10 μM. Similarly, nitrite (10 μM-2 mM) caused vasorelaxation of aortic rings, and NO was shown to be the intermediate factor responsible for this activity. With the use of electrochemical as well as electron paramagnetic resonance (EPR) spectroscopy techniques NO generation was measured from isolated aortic vessels following nitrite treatment. Reduction of nitrite to NO was blocked by heating the vessel, suggesting that an enzymatic process is involved. Organ chamber experiments demonstrated that aortic relaxation induced by nitrite could be blocked by both hemoglobin and soluble guanylyl cyclase (sGC) inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxaline-1-one (ODQ). In addition, both electrochemical and EPR spin-trapping measurements showed that ODQ inhibits nitrite-mediated NO production. These findings thus suggest that nitrite can be a precursor of EDRF and that sGC or other heme proteins inhibited by ODQ catalyze the reduction of nitrite to NO.

Estimating oxygen transport resistance of the microvascular wall

2000 ◽  
Vol 279 (2) ◽  
pp. H657-H671 ◽  
Author(s):  
Arjun Vadapalli ◽  
Roland N. Pittman ◽  
Aleksander S. Popel
Keyword(s):  
Nitric Oxide ◽  
Endothelial Cells ◽  
Smooth Muscle ◽  
Diffusion Model ◽  
Oxygen Transport ◽  
Vascular Wall ◽  
Nitric Oxide Production ◽  
Endothelial Surface

The problem of diffusion of O2 across the endothelial surface in precapillary vessels and its utilization in the vascular wall remains unresolved. To establish a relationship between precapillary release of O2 and vascular wall consumption, we estimated the intravascular flux of O2 on the basis of published in vivo measurements. To interpret the data, we utilized a diffusion model of the vascular wall and computed possible physiological ranges for O2 consumption. We found that many flux values were not consistent with the diffusion model. We estimated the mitochondrial-based maximum O2 consumption of the vascular wall (Mmt) and a possible contribution to O2 consumption of nitric oxide production by endothelial cells (MNO). Many values of O2 consumption predicted from the diffusion model exceeded Mmt + MNO. In contrast, reported values of O2consumption for endothelial and smooth muscle cell suspensions and vascular strips in vitro do not exceed Mmt. We conjecture that most of the reported values of intravascular O2 flux are overestimated, and the likely source is in the experimental estimates of convective O2 transport at upstream and downstream points of unbranched vascular segments.

Female gametophyte-controlled pollen tube guidance

2010 ◽  
Vol 38 (2) ◽  
pp. 627-630 ◽  
Author(s):  
Mihaela-Luiza Márton ◽  
Thomas Dresselhaus
Keyword(s):  
Pollen Tube ◽  
Female Gametophyte ◽  
Cell Communication ◽  
Flowering Plants ◽  
Sperm Cells ◽  
Double Fertilization ◽  
Pollen Tube Guidance ◽  
Communication Events ◽  
Extensive Cell

During the evolution of flowering plants, their sperm cells have lost mobility and are transported from the stigma to the female gametophyte via the pollen tube to achieve double fertilization. Pollen tube growth and guidance is largely governed by the maternal sporophytic tissues of the stigma, style and ovule. However, the last phase of the pollen tube path is under female gametophyte control and is expected to require extensive cell–cell communication events between both gametophytes. Until recently, little was known about the molecules produced by the female gametophyte that are involved in this process. In the present paper, we review the most recent development in this field and focus on the role of secreted candidate signalling ligands.

Thrombin Does Not Alter Vascular Hyporeactivity in Models of Endotoxin-Induced Septic Shock in Rats

1995 ◽  
Vol 88 (2) ◽  
pp. 149-157 ◽  
Author(s):  
Viviane Martin ◽  
Marie-Louise Wiesel ◽  
Anne Albert ◽  
Alain Beretz
Keyword(s):  
Nitric Oxide ◽  
Disseminated Intravascular Coagulation ◽  
Vascular Tone ◽  
Endotoxic Shock ◽  
Vascular Wall ◽  
Anticoagulant Treatment ◽  
Intravascular Coagulation ◽  
Vascular Hyporeactivity

1. Hypotension and vascular hyporesponsiveness to vasoconstrictors are observed during endotoxic shock, and are associated with increased production of nitric oxide in the vascular wall. Disseminated intravascular coagulation is another feature of septicaemia. We hypothesized that thrombin generated during disseminated intravascular coagulation might modulate the changes in vascular tone induced by endotoxin. 2. Incubation of rat aortic rings for 4 h with α-thrombin (0.003–3.0 NIH units/ml) did not change their reactivity to noradrenaline. Incubation for 4 h with lipopolysaccharide increased the EC50 for noradrenaline, whereas co-incubation of thrombin (0.5 NIH units/ml) with lipopolysaccharide did not alter this hyporeactivity to noradrenaline. 3. In vivo in rats, lipopolysaccharide caused early (1 h) and late (4–6 h) hyporeactivity to noradrenaline. In rats infused with lipopolysaccharide and heparin (1 U min−1 kg−1, 0.4 ml/h) or hirudin (2.2 mg ml−1 kg−1, 0.8 ml/h), vasopressor responses to noradrenaline were not different from those after infusion of lipopolysaccharide alone. Aortic rings taken from rats receiving both anticoagulant treatment and lipopolysaccharide had the same sensitivity to noradrenaline as those obtained from rats receiving lipopolysaccharide alone. 4. Our results suggest that, in vivo, disseminated intravascular coagulation does not modify the early and late effects of lipopolysaccharide on arterial pressure and that, in vitro, thrombin neither induces hyporeactivity to noradrenaline nor modifies lipopolysaccharide-induced hyporeactivity. We propose that thrombin generated during disseminated intravascular coagulation in rats does not play a major role in the alterations of vascular tone observed during endotoxic shock.

scholarly journals Female gametophyte expressed Arabidopsis thaliana lipid transfer proteins AtLtpI.4 and AtLtpI.8 provide a link between callose homeostasis, pollen tube guidance, and fertilization success

2021 ◽  
Author(s):  
Khushbu Kumari ◽  
Meng Zhao ◽  
Sebastian Britz ◽  
Christine Weiste ◽  
Wolfgang Dröge-Laser ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Pollen Tube ◽  
Female Gametophyte ◽  
Control Cell ◽  
Cell Communication ◽  
Large Family ◽  
Fertilization Success ◽  
Lipid Transfer ◽  
Lipid Transfer Proteins ◽  
Pollen Tube Guidance

ABSTRACTNon-specific lipid transfer proteins (LTPs) represent a sub-class among the large family of Cysteine-rich proteins (CRPs) specific to land plants. LTPs possess a hydrophobic cavity, enabling them to bind and stabilize a variety of lipid molecules outside membranes. In line with the existence of an N-terminal signal peptide, secreted LTPs represent a well-suited mobile signal carrier in the plant’s extracellular matrix. Thus, LTPs are currently considered as key players to mediate the bulk flow of lipids between membranes/compartments as well as the buildup of lipid barrier polymers including cutin and suberin.Here, we show that floral expressed Arabidopsis thaliana AtLtpI.4 (AtLTP2) and AtLtpI.8 (AtLTP5), mutually control cell-cell communication between growing pollen tubes and ovules during fertilization. Arabidopsis mutants lacking functional AtLtpI.4 and AtLtpI.8 exhibit significantly reduced fertilization success. Cross-pollination and cell biological analyses revealed that AtLtpI.4/I.8 double mutants are impaired in pollen tube guidance towards ovules. Our finding that the AtLtpI.4/I.8 phenotype correlates with aberrant callose depositions in the micropylar region during ovule development suggests that both LTPs represent novel players of a joint signaling pathway that controls callose homeostasis in the female gametophyte.

Pollination in Arabidopsis Thaliana

1998 ◽  
Vol 4 (S2) ◽  
pp. 1180-1181
Author(s):  
K. Lennon ◽  
E. Lord
Keyword(s):  
Pollen Tube ◽  
Cell Communication ◽  
Embryo Sac ◽  
Pollen Grain ◽  
Secretory Cells ◽  
Higher Plant ◽  
Transmitting Tissue ◽  
Pollen Tube Guidance ◽  
Complex Processes ◽  
Communication Events

In flowering plants, pollination and the process of fertilization are complex processes involving a series of cell-to-cell communication events. Though details of the progression of the pollen tube through the pistil, beginning with germination of the pollen grain on the stigma and culminating with delivery of the sperm cells to the embryo sac, are well established for several higher plant species, the mechanisms involved have yet to be elucidated. It has been shown that the transmitting tissue, which coincides with the path of pollen tubes in the gynoecium, is composed of highly secretory cells characterized by an extensive extracellular matrix (ECM). The actual roles that this ECM plays in pollination are currently unknown, although functions proposed include mechanical and/or chemotropic pollen tube guidance as well as pollen tube nutrition.

502: Pressure Induces Nitric Oxide Production by Human Ureteral Cells in Vitro

2005 ◽  
Vol 173 (4S) ◽  
pp. 137-137
Author(s):  
Michael M. Ohebshalom ◽  
Stella K. Maeng ◽  
Jie Chen ◽  
Dix P. Poppas ◽  
Diane Felsen
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Production ◽  
Oxide Production

Effects of sodium nitroprusside(a donor of nitric oxide) on development of porcine preantral follicle cultured in vitro

2011 ◽  
Vol 37 (1) ◽  
pp. 55-59
Author(s):  
Qing QUAN ◽  
Yong TAO ◽  
Xiao-rong ZHANG ◽  
Gui-dong YAO ◽  
Jin-ju WANG
Keyword(s):  
Nitric Oxide ◽  
Sodium Nitroprusside ◽  
Preantral Follicle
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