Effect of Certain Quinones, Diquat, and Diuron on Chlorella pyrenoidosa Chick. (Emerson strain)

Weed Science ◽  
1968 ◽  
Vol 16 (1) ◽  
pp. 69-73 ◽  
Author(s):  
G. Zweig ◽  
J. E. Hitt ◽  
R. McMahon
Keyword(s):  
Chlorophyll Content ◽  
Oxygen Evolution ◽  
Physiological Activity ◽  
Chlorophyll Concentration ◽  
Chlorella Pyrenoidosa ◽  
Inhibitory Effect ◽  
Cell Number ◽  
Drastic Decrease ◽  
Oxygen Evolving

The effect of 1,4-naphthoquinone, 1,4-benzoquinone, and several CI and NH2-substituted quinones has been studied on growth, chlorophyll concentration, and oxygen evolution in Chlorella pyrenoidosa Chick. (Emerson strain). Drastic decrease of the studied parameters usually was noted after 24 to 48 hr treatment at 3×10–5 M concentration. The effect of the quinones was compared with that of 6,7-dihydrodipyrido [l,2-a:2,l-c-]pyrazidinium salt (diquat) and 3-(3,4-dichlorophenyl)-l,l-dimethylurea (diuron). Diuron inhibited oxygen evolution immediately after addition, but could be washed out and the effect was reversible. Diquat had no inhibitory effect on oxygen evolution and chlorophyll content but caused a slight decrease in cell number. Although some quinones have an almost immediate effect on the oxygen-evolving mechanism, it seems more likely that the overall effect of the quinones is on the total physiological activity of the algal cells. Oxygen evolution seems to affected earlier than chlorophyll destruction, and the observed long-term damage is irreversible. Most of the compounds studied could be classified as algicidal, with the exception of diuron, diquat, and 1,4-benzoquinone which may be considered to be algistatic.

Determination and Characterization of the Effects of Fluometuron and MSMA onChlorella

Weed Science ◽  
1979 ◽  
Vol 27 (3) ◽  
pp. 294-299 ◽  
Author(s):  
T. O. Blythe ◽  
S. M. Grooms ◽  
R. E. Frans
Keyword(s):  
Kinetic Analysis ◽  
Oxygen Evolution ◽  
Chlorella Pyrenoidosa ◽  
Cell Number ◽  
Probit Analysis ◽  
Heterotrophic Growth ◽  
Autotrophic Growth ◽  
University Of Texas ◽  
Unicellular Green Alga

Studies were conducted on the effects of fluometuron [1,1-dimethyl-3-(α,α,α-trifluoro-m-tolyl)urea] on autotrophic growth (no sugar), heterotrophic growth (with sugar), and oxygen evolution and uptake and on the effects of MSMA (monosodium methanearsonate) on autotrophic growth and oxygen evolution and uptake by the unicellular green algaChlorella pyrenoidosaEmerson strain (University of Texas). Two methods of analysis (probit and kinetic) were used to characterize the dosage-response ofChlorellato these herbicides. All measurements ofChlorellaresponse to fluometuron were satisfactorily characterized by probit analysis, but only autotrophic cell number was adequately characterized by kinetic analysis. The fluometuron concentrations giving 50% inhibition on the probit plot were as follows: autotrophic cell number, 2.4 × 10−6M; chlorophyll at 400 nm, 3.3 × 10−6M; heterotrophic cell number, 2.4 × 10−6M; oxygen evolution, 20 × 10−6M. The response of the alga to MSMA was stimulatory instead of inhibitory. Since this stimulation did not consistently range between 10 and 90% of the control, it was not possible to characterize the MSMA dosage-Chlorellaresponse using either type of analysis.

scholarly journals CULTURE CONDITIONS AND THE DEVELOPMENT OF THE PHOTOSYNTHETIC MECHANISM

1946 ◽  
Vol 29 (6) ◽  
pp. 419-427 ◽  
Author(s):  
Jack Myers ◽  
Keyword(s):  
Light Intensity ◽  
Cell Volume ◽  
Unit Cell Volume ◽  
Chlorophyll Concentration ◽  
Dry Weight ◽  
Chlorella Pyrenoidosa ◽  
Cell Number ◽  
Culture Conditions ◽  
Photosynthetic Unit ◽  
Incandescent Lamps

1. Chlorella pyrenoidosa has been grown in a continuous-culture apparatus under various light intensities provided by incandescent lamps, other conditions of culture being maintained constant. The harvested cells were analyzed for cell number, dry weight, nitrogen, and chlorophyll per unit cell volume. 2. Cell nitrogen and cell volume are parallel measures of cellular material over the range of light intensity studied. 3. The dry weight per cell volume increases slowly with light intensity, showing about a 20 per cent variation. 4. Chlorophyll concentration and cell number show a concomitant decrease with increasing light intensity, varying in such a way that there are always about the same number of chlorophyll molecules per cell. It is considered that this phenomenon has bearing on the interpretation of data which has led to the theory of the photosynthetic unit.

scholarly journals Robust Carbon-Stabilization of Few-Layer Black Phosphorus for Superior Oxygen Evolution Reaction

Coatings ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 695 ◽  
Author(s):  
Mengjie Zhang ◽  
Wenchang Zhu ◽  
Xingzhe Yang ◽  
Meng Feng ◽  
Hongbin Feng
Keyword(s):  
Oxygen Evolution ◽  
Oxygen Evolution Reaction ◽  
Black Phosphorus ◽  
Carbon Stabilization ◽  
High Durability ◽  
Carbon Coated ◽  
Alkaline Conditions ◽  
Doped Graphene ◽  
A Current

Few-layer exfoliated black phosphorus (Ex-BP) has attracted tremendous attention owing to its promising applications, including in electrocatalysis. However, it remains a challenge to directly use few-layer Ex-BP as oxygen-involved electrocatalyst because it is quite difficult to restrain structural degradation caused by spontaneous oxidation and keep it stable. Here, a robust carbon-stabilization strategy has been implemented to prepare carbon-coated Ex-BP/N-doped graphene nanosheet (Ex-BP/NGS@C) nanostructures at room temperature, which exhibit superior oxygen evolution reaction (OER) activity under alkaline conditions. Specifically, the as-synthesized Ex-BP/NGS@C hybrid presents a low overpotential of 257 mV at a current density of 10 mA cm−2 with a small Tafel slope of 52 mV dec−1 and shows high durability after long-term testing.

Effect of Anticonvulsants on the Uptake of 5-Methyltetrahydrofolic Acid by the Choroid Plexus in Rabbits

1977 ◽  
Vol 53 (1) ◽  
pp. 75-80
Author(s):  
H. Taguchi ◽  
Z. Abdul-Cader ◽  
J. Perry ◽  
E. H. Reynolds ◽  
I. Chanarin
Keyword(s):  
Folic Acid ◽  
Low Temperature ◽  
Choroid Plexus ◽  
Incubation Medium ◽  
Pernicious Anaemia ◽  
Inhibitory Effect ◽  
Anaerobic Conditions ◽  
Acid Therapy ◽  
Pteroylglutamic Acid

1. The isolated choroid plexus of the rabbit takes up 5-methyltetrahydrofolate from the incubation medium. 2. Other folate analogues (pteroylglutamic acid, methotrexate, 5-formyltetrahydrofolate = folinic acid) inhibited the uptake of 5-methyltetrahydrofolate. 3. The uptake of 5-methyltetrahydrofolate was inhibited by low temperature, anaerobic conditions and dinitrophenol. 4. The anticonvulsant drugs, diphenylhydantoin and phenobarbital, had no effect on 5-methyltetrahydrofolate uptake. 5. The inhibitory effect of pteroylglutamic acid on the uptake of 5-methyltetrahydrofolate by the choroid plexus may explain the effect of long-term folic acid therapy in aggravating vitamin B12 neuropathy in pernicious anaemia.

Influence of N-methyl-d-aspartate on the reproductive axis of male Syrian hamsters

1993 ◽  
Vol 137 (2) ◽  
pp. 247-NP ◽  
Author(s):  
H. F. Urbanski ◽  
M. M. Fahy ◽  
P. M. Collins
Keyword(s):  
Hormone Secretion ◽  
Serum Testosterone ◽  
Inhibitory Effect ◽  
Stimulatory Action ◽  
Syrian Hamsters ◽  
Reproductive Axis ◽  
Treatment Paradigm ◽  
Testicular Size ◽  
Lh Releasing Hormone

ABSTRACT The influence of excitatory amino acids (EAAs) on reproductive neuroendocrine function was investigated in adult male Syrian hamsters of the LSH/Ss Lak strain. Before the study, the animals were maintained in a sexually regressed condition, under short days (SD) and subsequently were either transferred to long days (LD) or kept under SD, for a further 4 weeks. In the former group, photostimulation produced a predictable elevation in the hypophysial contents and serum concentrations of FSH and LH. This was accompanied by an increase in testicular size, an elevation in serum testosterone levels and an increase in spermatogenic activity; the SD hamsters remained sexually quiescent throughout the study. In contrast, SD hamsters that were given daily injections of the EAA agonist, N-methyl-d,l-aspartate (NMA: 50 mg/kg body weight, s.c.), showed stimulatory responses that were generally even more pronounced than those shown by the LD group. Surprisingly, an identical NMA treatment paradigm failed to cause a similar activation of the reproductive axis in LD hamsters that were given daily afternoon injections of melatonin (25 μg, s.c), even though the inhibitory effect of this melatonin treatment is generally regarded as being comparable with that produced by exposure to SD. Although EAAs can acutely stimulate the neurocircuitry that controls LH-releasing hormone secretion, the present findings suggest that EAAs might also exert a long-term stimulatory action by acting further upstream in the photoneuroendocrine pathway. Journal of Endocrinology (1993) 137, 247–252

scholarly journals Effect of Cell Growth on Hepatitis C Virus (HCV) Replication and a Mechanism of Cell Confluence-Based Inhibition of HCV RNA and Protein Expression

2006 ◽  
Vol 80 (3) ◽  
pp. 1181-1190 ◽  
Author(s):  
Heather B. Nelson ◽  
Hengli Tang
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Cell Growth ◽  
De Novo ◽  
Physiological State ◽  
Inhibitory Effect ◽  
Cell Number ◽  
Serum Starvation ◽  
Hcv Rna ◽  
Cell Growth Arrest

ABSTRACT An intimate relationship between hepatitis C virus (HCV) replication and the physiological state of the host liver cells has been reported. In particular, a highly reproducible and reversible inhibitory effect of high cell density on HCV replication was observed: high levels of HCV RNA and protein can be detected in actively growing cells but decline sharply when the replicon cells reach confluence. Arrested cell growth of confluent cells has been proposed to be responsible for the inhibitory effect. Indeed, other means of arresting cell growth have also been shown to inhibit HCV replication. Here, we report a detailed study of the effect of cell growth and confluence on HCV replication using a flow cytometry-based assay that is not biased against cytostasis and reduced cell number. Although we readily reproduced the inhibitory effect of cell confluence on HCV replication, we found no evidence of inhibition by serum starvation, which arrested cell growth as expected. In addition, we observed no inhibitory effect by agents that perturb the cell cycle. Instead, our results suggest that the reduced intracellular pools of nucleosides account for the suppression of HCV expression in confluent cells, possibly through the shutoff of the de novo nucleoside biosynthetic pathway when cells become confluent. Adding exogenous uridine and cytidine to the culture medium restored HCV replication and expression in confluent cells. These results suggest that cell growth arrest is not sufficient for HCV replicon inhibition and reveal a mechanism for HCV RNA inhibition by cell confluence.

Inhibitory effect of ipriflavone on osteoclast-mediated bone resorption and new osteoclast formation in long-term cultures of mouse unfractionated bone cells

1993 ◽  
Vol 53 (3) ◽  
pp. 206-209 ◽  
Author(s):  
Kohei Notoya ◽  
Keiji Yoshida ◽  
Shigehisa Taketomi ◽  
Iwao Yamazaki ◽  
Masayoshi Kumegawa
Keyword(s):  
Bone Resorption ◽  
Bone Cells ◽  
Inhibitory Effect ◽  
Osteoclast Formation

Long term exposure to dopamine reverses the inhibitory effect of endothelin-1 on prolactin secretion.

Endocrinology ◽  
1995 ◽  
Vol 136 (3) ◽  
pp. 990-994 ◽  
Author(s):  
B Kanyicska ◽  
J D Livingstone ◽  
M E Freeman
Keyword(s):  
Inhibitory Effect ◽  
Prolactin Secretion ◽  
Endothelin 1

scholarly journals The Anti-inflammatory Cytokine, Interleukin (IL)-10, Blocks the Inhibitory Effect of IL-1β on Long Term Potentiation

2001 ◽  
Vol 276 (49) ◽  
pp. 45564-45572 ◽  
Author(s):  
Áine Kelly ◽  
Aileen Lynch ◽  
Emily Vereker ◽  
Yvonne Nolan ◽  
Patrice Queenan ◽  
...  
Keyword(s):  
Inflammatory Cytokine ◽  
Long Term Potentiation ◽  
Inhibitory Effect ◽  
Term Potentiation ◽  
Anti Inflammatory ◽  
Anti Inflammatory Cytokine

scholarly journals Effects of low-dose aspirin on the osseointegration process in rats

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Ana Carolina Lupepsa ◽  
Paula Vargas-Sanchez ◽  
Marcella Goetz Moro ◽  
Leomar Emanuel Almeida Mecca ◽  
Marcela Claudino ◽  
...  
Keyword(s):  
Low Dose ◽  
Inhibitory Effect ◽  
Control Group ◽  
Implant Placement ◽  
Dose Aspirin ◽  
Low Dose Aspirin ◽  
Male Wistar Rats ◽  
Bone To Implant Contact ◽  
Bone Deposition

Abstract Background Several drugs are capable of promoting changes in bone metabolism. The aim of this study was to evaluate the effect of long-term low-dose aspirin (LDA) therapy on implant osseointegration. Methods Male Wistar rats were divided into 4 groups (n = 8/group) according to oral gavage solution received prior (42 days) to the implant surgery on the tibia. The control group was treated with saline solution for 7 (CG-7) and 28 (CG-28) days. The use of low-dose aspirin was performed in AG groups (6.75 mg/kg of aspirin) for 7 (AG-7) and 28 (AG-28) days. After experimental periods, histomorphometric evaluation of bone-to-implant contact (BIC) and the bone area between threads (BABT) was performed. Results Reduced BIC values were detected in AG-7 (62.8% ± 17.1) group compared to AG-28 (91.9% ± 5.4), CG-7 (82.7% ± 15.2), and CG-28 (89.9% ± 9.7). BABT evaluation revealed lower values in AG-7 (70.9% ± 15.2) compared to AG-28 (95.4% ± 3.7) and CG-28 (87.1% ± 10.2) groups. Conclusions The treatment with low doses of aspirin promoted a discrete inhibitory effect in the early stages (7 days) of repair after implant placement, specifically in the bone deposition. However, these effects were not detected in the late stages (28 days), considering BIC and BABT parameters.

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