Hormonal responses during early embryogenesis in maize

2014 ◽  
Vol 42 (2) ◽  
pp. 325-331 ◽  
Author(s):  
Junyi Chen ◽  
Andreas Lausser ◽  
Thomas Dresselhaus
Keyword(s):  
Early Embryogenesis ◽  
Hormonal Response ◽  
Two Component System ◽  
Hormonal Responses ◽  
Embryo Patterning ◽  
Auxin Signalling ◽  
Model Plant Arabidopsis Thaliana ◽  
Endosperm Formation ◽  
Cytokinin Response

Plant hormones have been shown to regulate key processes during embryogenesis in the model plant Arabidopsis thaliana, but the mechanisms that determine the peculiar embryo pattern formation of monocots are largely unknown. Using the auxin and cytokinin response markers DR5 and TCSv2 (two-component system, cytokinin-responsive promoter version #2), as well as the auxin efflux carrier protein PIN1a (PINFORMED1a), we have studied the hormonal response during early embryogenesis (zygote towards transition stage) in the model and crop plant maize. Compared with the hormonal response in Arabidopsis, we found that detectable hormone activities inside the developing maize embryo appeared much later. Our observations indicate further an important role of auxin, PIN1a and cytokinin in endosperm formation shortly after fertilization. Apparent auxin signals within adaxial endosperm cells and cytokinin responses in the basal endosperm transfer layer as well as chalazal endosperm are characteristic for early seed development in maize. Moreover, auxin signalling in endosperm cells is likely to be involved in exogenous embryo patterning as auxin responses in the endosperm located around the embryo proper correlate with adaxial embryo differentiation and outgrowth. Overall, the comparison between Arabidopsis and maize hormone response and flux suggests intriguing mechanisms in monocots that are used to direct their embryo patterning, which is significantly different from that of eudicots.

Role of Auxin in Early Embryogenesis of Plants

2014 ◽  
Vol 48 (4) ◽  
pp. 371-380
Author(s):  
Song Lizhen ◽  
Wang Yi ◽  
Yang Qinghua ◽  
Cheng Youfa
Keyword(s):  
Early Embryogenesis

The role of PhoP/PhoQ two component system in regulating stress adaptation in Cronobacter sakazakii

2021 ◽  
pp. 103851
Author(s):  
Yan Ma ◽  
Yingying Zhang ◽  
Ke Chen ◽  
Lingzhu Zhang ◽  
Yibei Zhang ◽  
...  
Keyword(s):  
Stress Adaptation ◽  
Cronobacter Sakazakii ◽  
Two Component System ◽  
Component System ◽  
Two Component

scholarly journals Regulatory Role of the MisR/S Two-Component System in Hemoglobin Utilization in Neisseria meningitidis

2009 ◽  
Vol 78 (3) ◽  
pp. 1109-1122 ◽  
Author(s):  
Shuming Zhao ◽  
Grisselle E. Montanez ◽  
Pradeep Kumar ◽  
Soma Sannigrahi ◽  
Yih-Ling Tzeng
Keyword(s):  
Posttranscriptional Regulation ◽  
Regulatory Mechanisms ◽  
Two Component System ◽  
Gene Encoding ◽  
Positive Role ◽  
Upstream Gene ◽  
Component System ◽  
Two Component ◽  
Major Surface

ABSTRACT Outer membrane iron receptors are some of the major surface entities that are critical for meningococcal pathogenesis. The gene encoding the meningococcal hemoglobin receptor, HmbR, is both independently transcribed and transcriptionally linked to the upstream gene hemO, which encodes a heme oxygenase. The MisR/S two-component system was previously determined to regulate hmbR transcription, and its hemO and hmbR regulatory mechanisms were characterized further here. The expression of hemO and hmbR was downregulated in misR/S mutants under both iron-replete and iron-restricted conditions, and the downregulation could be reversed by complementation. No significant changes in expression of other iron receptors were detected, suggesting that the MisR/S system specifically regulates hmbR. When hemoglobin was the sole iron source, growth defects were detected in the mutants. Primer extension analysis identified a promoter upstream of the hemO-associated Correia element (CE) and another promoter at the proximal end of CE, and processed transcripts previously identified for other cotranscribed CEs were also detected, suggesting that there may be posttranscriptional regulation. MisR directly interacts with sequences upstream of the CE and upstream of the hmbR Fur binding site and thus independently regulates hemO and hmbR. Analysis of transcriptional reporters of hemO and hmbR further demonstrated the positive role of the MisR/S system and showed that the transcription of hmbR initiated from hemO was significantly reduced. A comparison of the effects of the misS mutation under iron-replete and iron-depleted conditions suggested that activation by the MisR/S system and iron-mediated repression by Fur act independently. Thus, the expression of hemO and hmbR is coordinately controlled by multiple independent regulatory mechanisms, including the MisR/S two-component system.

Role of hypothalamic inputs in maintaining pituitary-adrenal responsiveness in repeated restraint

2003 ◽  
Vol 285 (5) ◽  
pp. E1110-E1117 ◽  
Author(s):  
D. Zelena ◽  
Z. Mergl ◽  
A. Földes ◽  
K. J. Kovács ◽  
Z. Tóth ◽  
...  
Keyword(s):  
Chronic Stress ◽  
Stress Responses ◽  
Mrna Level ◽  
Hormonal Changes ◽  
Mediobasal Hypothalamus ◽  
Hormonal Responses ◽  
Pomc Mrna ◽  
Paraventricular Nucleus Of Hypothalamus ◽  
Pituitary Adrenal Axis

The role of hypothalamic structures in the regulation of chronic stress responses was studied by lesioning the mediobasal hypothalamus or the paraventricular nucleus of hypothalamus (PVH). Rats were acutely (60 min) and/or repeatedly (for 7 days) restrained. In controls, a single restraint elevated the plasma adrenocorticotropin (ACTH), corticosterone, and prolactin levels. Repeated restraint produced all signs of chronic stress, including decreased body and thymus weights, increased adrenal weight, basal corticosterone levels, and proopiomelanocortin (POMC) mRNA expression in the anterior pituitary. Some adaptation to repeated restraint of the ACTH response, but not of other hormonal responses, was seen. Lesioning of the mediobasal hypothalamus abolished the hormonal response and POMC mRNA activation to acute and/or repeated restraint, suggesting that the hypothalamo-pituitary-adrenal axis activation during repeated restraint is centrally driven. PVH lesion inhibited the ACTH and corticosterone rise to the first restraint by ∼50%. In repeatedly restrained rats with PVH lesion, the ACTH response to the last restraint was reduced almost to basal control levels, and the elevation of POMC mRNA level was prevented. PVH seems to be important for the repeated restraint-induced ACTH and POMC mRNA stimulation, but it appears to partially mediate other restraint-induced hormonal changes.

The role of neurohumours in early embryogenesis

Development ◽  
1970 ◽  
Vol 23 (3) ◽  
pp. 549-569
Author(s):  
G. A. Buznikov ◽  
A. N. Kost ◽  
N. F. Kucherova ◽  
A. L. Mndzhoyan ◽  
N. N. Suvorov ◽  
...  
Keyword(s):  
Sea Urchin ◽  
Functional Activity ◽  
Early Onset ◽  
Active Sites ◽  
Physiological Effect ◽  
Early Embryogenesis ◽  
Dopamine Synthesis ◽  
Direct Involvement ◽  
Misgurnus Fossilis

In previous papers (Buznikov, Chudakova & Zvezdina, 1964; Buznikov, Chudakova, Berdysheva & Vyazmina, 1968) we reported that fertilized eggs of the sea-urchin Strongylocentrotus dröbachiensis synthesized a number of neurohumours, such as serotonin (5-hydroxytryptamine, 5-HT), acetylcholine (ACh), adrenalin (A), noradrenalin (NA) and dopamine. Synthesis of 5-HT was also demonstrated in the fertilized eggs of the loach Misgurnus fossilis and some marine Invertebrata. In experiments with sea-urchin embryos we were able to trace regular changes in the level of 5-HT, ACh, A and NA, related to the first cleavage divisions. This early onset of neurohumour synthesis, as well as regular changes in their level, suggests their direct involvement in the regulation of the first cleavage divisions. The functional activity of neurohumours (M) in adult organisms is realized through their reaction with the active sites of corresponding receptors (R) according to the following equation:The magnitude of the physiological effect under certain conditions is linearly proportional to the number of complexes MR formed (Turpayev, 1962; Ariëns, 1964).

Role of right heart receptors in the control of renin, vasopressin, and cortisol secretion in dogs

1992 ◽  
Vol 263 (5) ◽  
pp. R1071-R1077 ◽  
Author(s):  
D. H. Carr ◽  
D. B. Jennings ◽  
T. N. Thrasher ◽  
L. C. Keil ◽  
D. J. Ramsay
Keyword(s):  
Inferior Vena ◽  
Vena Cava ◽  
Plasma Renin ◽  
Atrial Pressure ◽  
Right Atrial ◽  
Right Heart ◽  
Hormonal Responses ◽  
The Right ◽  
Maximal Reduction

We have reported that increased left heart pressure inhibits increases in plasma renin activity (PRA), arginine vasopressin (AVP), and cortisol during arterial hypotension. The goal of this study was to determine whether increases in right heart pressure also inhibited hormonal responses to hypotension. Seven dogs were chronically instrumented with inflatable cuffs around the ascending aorta (AA), the pulmonary artery (PA), and the thoracic inferior vena cava (IVC), as well as with catheters in both atria, the abdominal aorta, and vena cava. The IVC, the PA, and the AA cuffs were inflated on different days to cause step reductions in mean arterial pressure (MAP) of 5, 10, 20, and 30% below control MAP. Graded constriction of the AA caused large increases in left atrial pressure and plasma atrial natriuretic peptide (ANP), but had no effect on plasma AVP or cortisol and caused only a small increase in PRA at the maximal reduction of MAP. Constriction of the IVC reduced both atrial pressures and plasma ANP, but stimulated increases in PRA, AVP, and cortisol. Constriction of the PA increased right atrial pressure and plasma ANP and caused increases in plasma AVP and cortisol that were similar to responses during IVC constriction, but the PRA response was only half (P < 0.05). These results indicate that increasing pressure on the right side of the heart can attenuate the PRA response to hypotension, and suggest that the inhibition is mediated by the rise in plasma ANP.

Chromatin Diminution in Cyclops kolensis Lill. (Copepoda, Crustacea) as a Radical Way to Inactivate Redundant Genome in Somatic Cells

2018 ◽  
Vol 156 (3) ◽  
pp. 165-172 ◽  
Author(s):  
Andrey K. Grishanin ◽  
Maxim V. Zagoskin
Keyword(s):  
Chromosome Number ◽  
Repetitive Sequences ◽  
Early Embryogenesis ◽  
Chromosome Size ◽  
Chromatin Diminution ◽  
Elimination Process ◽  
Dna Elimination ◽  
Molecular Studies ◽  
Cyclops Kolensis

Chromatin diminution (CD) is a phenomenon of programmed DNA elimination which takes place in early embryogenesis in some eukaryotes. The mechanism and biological role of CD remain largely unknown. During CD in the freshwater copepod Cyclops kolensis, the genome of cells of the somatic lineage is reorganized and reduced in size by more than 90% without affecting the genome of germline cells. Although the diploid chromosome number is unchanged, chromosome size is dramatically reduced by CD. The eliminated DNA consists primarily of repetitive sequences and localizes within granules during the elimination process. In this review, we provide an overview of CD in C. kolensis including both cytological and molecular studies.

scholarly journals The Staphylococcus aureus KdpDE Two-Component System Couples Extracellular K+Sensing and Agr Signaling to Infection Programming

2011 ◽  
Vol 79 (6) ◽  
pp. 2154-2167 ◽  
Author(s):  
Ting Xue ◽  
Yibo You ◽  
De Hong ◽  
Haipeng Sun ◽  
Baolin Sun
Keyword(s):  
Staphylococcus Aureus ◽  
Uptake System ◽  
Main Function ◽  
Two Component System ◽  
Component System ◽  
Content Type ◽  
Two Component ◽  
Virulence Regulator ◽  
External K

ABSTRACTThe Kdp system is widely distributed among bacteria. InEscherichia coli, the Kdp-ATPase is a high-affinity K+uptake system and its expression is activated by the KdpDE two-component system in response to K+limitation or salt stress. However, information about the role of this system in many bacteria still remains obscure. Here we demonstrate that KdpFABC inStaphylococcus aureusis not a major K+transporter and that the main function of KdpDE is not associated with K+transport but that instead it regulates transcription for a series of virulence factors through sensing external K+concentrations, indicating that this bacterium might modulate its infectious status through sensing specific external K+stimuli in different environments. Our results further reveal thatS. aureusKdpDE is upregulated by the Agr/RNAIII system, which suggests that KdpDE may be an important virulence regulator coordinating the external K+sensing and Agr signaling during pathogenesis in this bacterium.

scholarly journals The CasKR Two-Component System Is Required for the Growth of Mesophilic and Psychrotolerant Bacillus cereus Strains at Low Temperatures

2014 ◽  
Vol 80 (8) ◽  
pp. 2493-2503 ◽  
Author(s):  
Sara Esther Diomandé ◽  
Stéphanie Chamot ◽  
Vera Antolinos ◽  
Florian Vasai ◽  
Marie-Hélène Guinebretière ◽  
...  
Keyword(s):  
Bacillus Cereus ◽  
Food Poisoning ◽  
Two Component System ◽  
Diverse Range ◽  
Component System ◽  
Content Type ◽  
Two Component ◽  
Temperature Ranges ◽  
Different Strains

ABSTRACTThe different strains ofBacillus cereuscan grow at temperatures covering a very diverse range. SomeB. cereusstrains can grow in chilled food and consequently cause food poisoning. We have identified a new sensor/regulator mechanism involved in low-temperatureB. cereusgrowth. Construction of a mutant of this two-component system enabled us to show that this system, called CasKR, is required for growth at the minimal temperature (Tmin). CasKR was also involved in optimal cold growth aboveTminand in cell survival belowTmin. Microscopic observation showed that CasKR plays a key role in cell shape during cold growth. Introducing thecasKRgenes in a ΔcasKRmutant restored its ability to grow atTmin. Although it was first identified in the ATCC 14579 model strain, this mechanism has been conserved in most strains of theB. cereusgroup. We show that the role of CasKR in cold growth is similar in otherB. cereus sensu latostrains with different growth temperature ranges, including psychrotolerant strains.

ROLE OF THE OVIDUCT DURING EARLY EMBRYOGENESIS

1993 ◽  
Vol 28 (3) ◽  
pp. 189-192 ◽  
Author(s):  
F. Gandolfi ◽  
T. A. L. Brevini ◽  
S. Modina ◽  
R. Bianchi ◽  
L. Passoni
Keyword(s):  
Early Embryogenesis
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