Kinetin-Mediated Stimulation of Accumulation of Buckwheat Flavonoids in the Dark

1983 ◽  
Vol 38 (9-10) ◽  
pp. 711-718 ◽  
Author(s):  
U. Margna ◽  
T. Vainjärv
Keyword(s):  
Anthocyanin Biosynthesis ◽  
Flavonoid Biosynthesis ◽  
Accumulation Rates ◽  
Sharp Rise ◽  
Short Treatment ◽  
Exogenous Substrate ◽  
Percent Increase ◽  
High Level ◽  
Fold Stimulation ◽  
Stimulation Of

A short treatment of excised buckwheat cotyledons with a solution of kinetin lead to an up to 9-fold stimulation of anthocyanin biosynthesis, to an about 50 percent increase in the accumula­tion of rutin, and to an about 30 percent increase, on the average, in the accumulation of C-glycosylflavones in the treated material during its posttreatment incubation in the dark. When the treated cotyledons were incubated in a solution of ʟ--phenylalanine anthocyanin accumulation in the dark practically attained the same high level as it was observed in the illuminated cotyledons fed with exogenous ʟ--phenylalanine. In experiments with l4C-labelled L-phenylalanine kinetin induced a sharp rise in the labelling (resp. in the utilization of exogenous substrate for biosynthesis) of anthocyanins and rutin in the dark and a slight increase in the radioactivity of C-glycosylflavones. Similar labelling changes occurred in the illuminated cotyledons. However, both kinetin and light still more effectively promoted biosynthetic use of the endogenous sub­strate. As a result the relative portion of flavonoids formed from exogenous L-phenylalanine under these conditions showed a decrease as compared with the ratio of precursor use in the un­treated cotyledons. The results show that low accumulation rates of anthocyanins and other flavo­noids in the dark are conditioned by the limited access of substrate (ʟ--phenylalanine) molecules to the flavonoid enzymes lending further support to the idea that flavonoid biosynthesis is normally controlled at the substrate rather than at the enzymic level.

Swelling-activated transport of taurine in cultured gill cells of sea bass: physiological adaptation and pavement cell plasticity

2009 ◽  
Vol 296 (4) ◽  
pp. R1149-R1160 ◽  
Author(s):  
Martine Avella ◽  
Olivier Ducoudret ◽  
Didier F. Pisani ◽  
Philippe Poujeol
Keyword(s):  
Sea Bass ◽  
Physiological Adaptation ◽  
Dimensional Structure ◽  
Taurine Transport ◽  
Hypotonic Shock ◽  
Cells In Culture ◽  
Membrane Stretch ◽  
Gill Cells ◽  
Fold Stimulation ◽  
Stimulation Of

We have investigated volume-activated taurine transport and ultrastructural swelling response of sea bass gill cells in culture, assuming that euryhaline fish may have developed particularly efficient mechanisms of salinity adaptation. In vivo, when sea basses were progressively transferred from seawater to freshwater, we noticed a decrease in blood osmotic pressure. When gill cells in culture were subjected to 30% hypotonic shock, we observed a five-fold stimulation of [3H]taurine efflux. This transport was reduced by various anion channel inhibitors with the following efficiency: 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB) > niflumic acid > DIDS = diphenylamine-2-carboxylic acid. With polarized gill cells in culture, the hypotonic shock produced a five-fold stimulation of apical taurine transport, whereas basolateral exit was 25 times higher. Experiments using ionomycin, thapsigargin, BAPTA-AM, or removal of extracellular calcium suggested that taurine transport was regulated by external calcium. The inhibitory effects of lanthanum and streptomycin support Ca2+ entry through mechanosensitive Ca2+ channels. Branchial cells also showed hypotonically activated anionic currents sensitive to DIDS and NPPB. Similar pharmacology and time course suggested the potential existence of a common pathway for osmosensitive taurine and Cl− efflux through volume-sensitive organic osmolyte and anion channels. A three-dimensional structure study revealed that respiratory gill cells began to swell only 15 s after hypoosmotic shock. Apical microridges showed membrane outfoldings: the cell surface became smoother with a progressive disappearance of ridges. Therefore, osmotic swelling may not actually induce membrane stretch per se, inasmuch as the microridges may provide a reserve of surface area. This work demonstrates mechanisms of functional and morphological plasticity of branchial cells during osmotic stress.

Integrative Transcriptomic, and Proteomic Analysis of Flavonoid Biosynthesis During Fruit Maturation In Chinese Raspberry “Rubus Chingii Hu”

2021 ◽  
Author(s):  
Xiaobai Li ◽  
Jian Sun ◽  
Jingyong Jiang ◽  
Zhen Chen ◽  
Aaron Jackson
Keyword(s):  
Anthocyanin Biosynthesis ◽  
Flavonoid Biosynthesis ◽  
Fruit Maturation ◽  
Genetic Base ◽  
Kaempferol Glycosides ◽  
Flavonoid Composition ◽  
Rubus Chingii ◽  
Rubus Chingii Hu ◽  
Anthocyanin Production ◽  
Low Expression

Abstract Rubus chingii, is a red-fruited species of Rubus native to China, which is a popular and nutritious fruit in China. However, change in flavonoid composition and content during fruit maturation is poorly understood. This study examined flavonoids and the genes/proteins during four fruit ripening phases using LC-MS/MS. As a result, six major kinds of anthocyanins were first identified in R. chingii, which primarily consisted of flavanol-anthocyanins, are new to Rubus. Apart from anthocyanins, concentrations of fruit flavonoids were much higher than most berries including raspberries, and it is this that contributes to their high phenolic concentrations and antioxidant capabilities. In contrast to other known raspberries, R. chingii had a decline in flavonoids during fruit maturation, which was due to down-regulation of genes/proteins involved in phenylpropanoid and flavonoid biosynthesis. Surprisingly, anthocyanin continuously decreased during fruit coloration. This suggests that anthocyanins are not responsible for the fruit’s reddish coloration. The biosynthesis of these flavanol-anthocyanins consumed two flavonoid units both produced through the same upstream pathway. Their presence indicates a reduction in the potential biosynthesis of anthocyanin production. Also, the constantly low expression of RcANS gene down-regulated overall anthocyanin biosynthesis. The lack of RcF3’5’H gene/protein hindered the production of delphinidin glycosides. Flavonoids primarily comprising of quercetin/kaempferol-glycosides were predominately located at fruit epidermal-hair and placentae. The profile and biosynthesis of R. chingii flavonoids are unique to Rubus. It could be used to broaden the genetic base of raspberry cultivars and to improve their fruit quality.

scholarly journals Performance of the national fencing team of Ukraine at the XXXII Olympic Games and the prospects of its performance at the next Olympic Games

2021 ◽  
pp. 84-87
Author(s):  
Olga Kuvaldina ◽  
Volodymyr Driukov
Keyword(s):  
Olympic Games ◽  
Crucial Importance ◽  
Team Members ◽  
National Team ◽  
Sports Events ◽  
The World ◽  
High Level ◽  
Sports Statistics ◽  
Stimulation Of ◽  
The Olympic Games

Analysis of Ukrainian athletes’ results at the XXXII Olympiad Games allows pointing out the factors of the weak performance of Ukrainian athletes in women's individual saber and epee competitions, as well as men's team epee competitions, despite the possibility of winning medals in these sports events according to many analysts including those of Infostrada Sports and other sports statistics experts. These, in our opinion, include an unsatisfactory level of efficiency of the process of reaching the peak of readiness for the Olympic Games; lack of psychological stability of athletes at the competitions; weak tactical preparation of some athletes. Based on the performances of athletes of the Ukrainian fencing team in Tokyo, a conclusion was made about the unsatisfactory level of athletes’ preparation for the XXXII Olympic Games. Only 20% of the national team members were able to realize their potential at the XXXII Olympic Games. The dynamics of the athletes’ results at the World Championships 2017 – 2019 indicates the need to use in the new Olympic cycle the planning, which is focused on our athletes reaching the peak of readiness for the Olympics: at first, the training should be aimed at the maximum stimulation of the growth of sportsmanship, whereas at the final stage it should be focused on its realization in the major competitions. It is shown that despite the unsuccessful performance of the Ukrainian fencing team in the Olympic Tokyo, this type of martial arts has significant potential for improving sports achievements at the XXXIII Olympic Games 2024 in Paris. It is noted that in the new Olympic cycle it is of crucial importance to identify candidates for the XXXIII Olympic Games as soon as possible and to create all the conditions for their full-fledged preparation. Thus, to ensure further winning medal places at the Olympic Games, it is necessary to improve the system of sports training in the Olympic cycle, which envisages participation in numerous competitions during the year to achieve a high level of readiness in the major competitions of triennial – the Olympic Games.

scholarly journals The Flavonoid Biosynthesis Network in Plants

2021 ◽  
Vol 22 (23) ◽  
pp. 12824
Author(s):  
Weixin Liu ◽  
Yi Feng ◽  
Suhang Yu ◽  
Zhengqi Fan ◽  
Xinlei Li ◽  
...  
Keyword(s):  
Biosynthetic Pathway ◽  
Current Knowledge ◽  
Anthocyanin Biosynthesis ◽  
Basic Structure ◽  
Ring Structure ◽  
Flavonoid Biosynthesis ◽  
Comprehensive Overview ◽  
Flavonoid Biosynthetic Pathway ◽  
Intermediate Metabolites ◽  
Important Intermediate

Flavonoids are an important class of secondary metabolites widely found in plants, contributing to plant growth and development and having prominent applications in food and medicine. The biosynthesis of flavonoids has long been the focus of intense research in plant biology. Flavonoids are derived from the phenylpropanoid metabolic pathway, and have a basic structure that comprises a C15 benzene ring structure of C6-C3-C6. Over recent decades, a considerable number of studies have been directed at elucidating the mechanisms involved in flavonoid biosynthesis in plants. In this review, we systematically summarize the flavonoid biosynthetic pathway. We further assemble an exhaustive map of flavonoid biosynthesis in plants comprising eight branches (stilbene, aurone, flavone, isoflavone, flavonol, phlobaphene, proanthocyanidin, and anthocyanin biosynthesis) and four important intermediate metabolites (chalcone, flavanone, dihydroflavonol, and leucoanthocyanidin). This review affords a comprehensive overview of the current knowledge regarding flavonoid biosynthesis, and provides the theoretical basis for further elucidating the pathways involved in the biosynthesis of flavonoids, which will aid in better understanding their functions and potential uses.

scholarly journals Stimulation of the alternative oxidase of Neurospora crassa by Nucleoside phosphates

1980 ◽  
Vol 188 (1) ◽  
pp. 141-144 ◽  
Author(s):  
J Vanderleyden ◽  
C Peeters ◽  
H Verachtert ◽  
H Bertrand
Keyword(s):  
Neurospora Crassa ◽  
Oxidase Activity ◽  
Alternative Oxidase ◽  
Purine Nucleoside ◽  
Submitochondrial Particles ◽  
Fold Stimulation ◽  
Succinate Oxidase ◽  
Stimulation Of

The alternative-oxidase-mediated succinate oxidase activity of Neurospora crassa decreases drastically when mitochondria are fractionated into submitochondrial particles or treated with deoxycholate. The activity, however, can be completely restored in the presence of nucleoside 5′-monophosphates. The purine nucleoside 5′-monophosphates are more effective than the pyrimidine homologues. 5′-GMP gives a 10-fold stimulation of the alternative-oxidase-mediated succinate oxidase activity in submitochondrial particles. A comparison is made with the results obtained earlier with Moniliella tomentosa [Hanssens & Verachtert (1976) J. Bacteriol. 125, 825–835; Vanderleyden, Van Den Eynde & Verachtert (1980) Biochem. J. 186, 309–316].

scholarly journals Glucose stimulates somatostatin secretion in pancreatic δ-cells by cAMP-dependent intracellular Ca2+ release

2019 ◽  
Vol 151 (9) ◽  
Author(s):  
Geoffrey Denwood ◽  
Andrei Tarasov ◽  
Albert Salehi ◽  
Elisa Vergari ◽  
Reshma Ramracheya ◽  
...  
Keyword(s):  
Electrical Activity ◽  
Secretory Vesicles ◽  
Glucose Levels ◽  
Somatostatin Secretion ◽  
Elevated Glucose ◽  
Mouse Islets ◽  
Underlying Mechanisms ◽  
Fold Stimulation ◽  
Cyclase Activator ◽  
Stimulation Of

Somatostatin secretion from pancreatic islet δ-cells is stimulated by elevated glucose levels, but the underlying mechanisms have only partially been elucidated. Here we show that glucose-induced somatostatin secretion (GISS) involves both membrane potential-dependent and -independent pathways. Although glucose-induced electrical activity triggers somatostatin release, the sugar also stimulates GISS via a cAMP-dependent stimulation of CICR and exocytosis of somatostatin. The latter effect is more quantitatively important and in mouse islets depolarized by 70 mM extracellular K+, increasing glucose from 1 mM to 20 mM produced an ∼3.5-fold stimulation of somatostatin secretion, an effect that was mimicked by the application of the adenylyl cyclase activator forskolin. Inhibiting cAMP-dependent pathways with PKI or ESI-05, which inhibit PKA and exchange protein directly activated by cAMP 2 (Epac2), respectively, reduced glucose/forskolin-induced somatostatin secretion. Ryanodine produced a similar effect that was not additive to that of the PKA or Epac2 inhibitors. Intracellular application of cAMP produced a concentration-dependent stimulation of somatostatin exocytosis and elevation of cytoplasmic Ca2+ ([Ca2+]i). Both effects were inhibited by ESI-05 and thapsigargin (an inhibitor of SERCA). By contrast, inhibition of PKA suppressed δ-cell exocytosis without affecting [Ca2+]i. Simultaneous recordings of electrical activity and [Ca2+]i in δ-cells expressing the genetically encoded Ca2+ indicator GCaMP3 revealed that the majority of glucose-induced [Ca2+]i spikes did not correlate with δ-cell electrical activity but instead reflected Ca2+ release from the ER. These spontaneous [Ca2+]i spikes are resistant to PKI but sensitive to ESI-05 or thapsigargin. We propose that cAMP links an increase in plasma glucose to stimulation of somatostatin secretion by promoting CICR, thus evoking exocytosis of somatostatin-containing secretory vesicles in the δ-cell.

Vitamin D3 and glucose-6-phosphate dehydrogenase in rat duodenal epithelial cells

1989 ◽  
Vol 257 (5) ◽  
pp. G760-G765
Author(s):  
L. B. Nasr ◽  
J. D. Monet ◽  
P. Lucas ◽  
C. A. Bader
Keyword(s):  
Vitamin D ◽  
Intraperitoneal Administration ◽  
Middle Part ◽  
G6pd Activity ◽  
Dihydroxyvitamin D3 ◽  
Rat Duodenum ◽  
High Level ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Stimulation Of

A microdensitometric method was employed to determine enzyme activities in situ in undisrupted tissue rat duodenum. The effect of 1 alpha,25-dihydroxyvitamin D3 [1,25(OH)2D3] on glucose-6-phosphate dehydrogenase (G6PD) activity and on the two utilization pathways of synthesized NADPH, H1 (mixed function oxidation) and H2 (biosynthesis), was studied. In normal animals, a crypt-to-villus gradient of G6PD activity and of both NADPH utilization pathways was observed. A high level of NADPH utilization occurred predominantly via the H2 pathway. In vitamin D-deficient rat animals, G6PD activity in the middle part of the villus was approximately 60% lower than in normal animals [10.05 +/- 0.35 vs. 3.95 +/- 0.26 (means +/- SE) A585.min-1.micron-3 X 10(5), P less than 0.001] with reduced NADPH utilization via the H2 pathway (8.39 +/- 0.49 vs. 2.73 +/- 0.43 A585.min-1.micron-3 X 10(5), P less than 0.001) but not the H1 pathway (1.65 +/- 0.17 vs. 1.22 +/- 0.19 A585.min-1.micron-3 X 10(5), P = NS). Intraperitoneal administration of 1,25(OH)2D3 (500 pmol) to vitamin D-deficient animals resulted in increased G6PD activity within 30 min (4.09 +/- 0.38 vs. 5.51 +/- 0.39 A585.min-1.micron-3 X 10(5), P less than 0.05), attaining normal levels within 2 h. The H2 but not the H1 pathway of NADPH utilization increased significantly in response to 1,25(OH)2D3. This increase is essentially located in the basal and middle parts of the villus. Thus 1,25(OH)2D3 may influence biosynthesis in the duodenum via stimulation of G6PD activity and the H2 pathway of NADPH utilization.

scholarly journals STEROID INHIBITION OF PROTEIN INCORPORATION BY ISOLATED AMPHIBIAN OOCYTES

1974 ◽  
Vol 61 (1) ◽  
pp. 26-34 ◽  
Author(s):  
Allen W. Schuetz ◽  
Robin A. Wallace ◽  
James N. Dumont
Keyword(s):  
Rana Pipiens ◽  
Follicle Cells ◽  
Blood Protein ◽  
Short Treatment ◽  
Nuclear Maturation ◽  
Desoxycorticosterone Acetate ◽  
Protein Incorporation ◽  
The Relationship ◽  
Stimulation Of

The relationship between blood protein (vitellogenin) incorporation and nuclear maturation was studied in individual amphibian oocytes after in vitro exposure to desoxycorticosterone acetate (DOCA). Isolated Rana pipiens oocytes were incubated in vitro with radioactively labeled oocyte yolk precursor ([3H]vitellogenin) obtained from estrogenized Xenopus laevis. Incorporation of labeled vitellogenin into the oocytes continued over a 24-h period. Oocytes simultaneously exposed to DOCA and to labeled vitellogenin exhibited both inhibition of vitellogenin incorporation and stimulation of nuclear maturation and cortical changes. Inhibition of vitellogenin incorporation was observed after approximately 9 h of incubation and was correlated with the time of nuclear breakdown. Preincubation of oocytes in steroid for 9 h essentially terminated vitellogenin incorporation. Incorporation of vitellogenin occurred after removal of follicle cells from the oocyte by a short treatment with EDTA. These results demonstrate the macromolecular vitellogenin transport system remains operative in oocytes which can undergo nuclear maturation and that the steroid DOCA can affect its function. Evidence suggests that the mechanism of steroid inhibition is in part the result of inhibition of the micropinocytotic process in the oocyte cortex.

Excitation-induced activation of the Na(+)-K+ pump in rat skeletal muscle

1994 ◽  
Vol 266 (4) ◽  
pp. C925-C934 ◽  
Author(s):  
M. E. Everts ◽  
T. Clausen
Keyword(s):  
Soleus Muscle ◽  
Contractile Activity ◽  
Activation Mechanism ◽  
Rat Skeletal Muscle ◽  
Ouabain Binding ◽  
Direct Stimulation ◽  
Rat Soleus Muscle ◽  
Fold Stimulation ◽  
86Rb Influx ◽  
Stimulation Of

The stimulating effect of excitation on the Na(+)-K+ pump was characterized in measurements of 22Na efflux, intracellular Na+ content, 86Rb influx, and [3H]ouabain binding in isolated rat soleus muscle. Direct stimulation (10 V, 1 ms, 2 Hz) rapidly increased 22Na efflux and 86Rb influx about twofold. These effects were blocked by tetracaine and ouabain, were not associated with any significant increase in intracellular Na+, and could not be attributed to a rise in extracellular K+. The stimulation of 22Na efflux was unaffected by tubocurarine, dantrolene, trifluoperazine, or bumetanide. Stimulation at 2 Hz increased the rate of [3H]ouabain binding by approximately 120% within 1 min, indicating an early specific activation of the Na(+)-K+ pump. Stimulation at 60 Hz for 10 s increased intracellular Na+ content by 58%. Reextrusion of Na+ was complete in 2 min and could be prevented by ouabain (10(-4) M) or by cooling to 0 degrees C. It is concluded that, in rat soleus muscle, excitation leads to a rapid and pronounced (up to 15-fold) stimulation of the Na(+)-K+ pump, even at modest increases in intracellular Na+. This activation mechanism may be essential for the maintenance of transmembrane Na(+)-K+ gradients and prompt recovery of excitability during contractile activity.

Sign in / Sign up

Export Citation Format

Share Document