A kinetic analysis of a step-up photosensory response of the ciliate Stentor coeruleus

1990 ◽  
Vol 36 (6) ◽  
pp. 414-418 ◽  
Author(s):  
Michael J. Doughty
Keyword(s):  
White Light ◽  
Response Duration ◽  
Fluorescent Light ◽  
Threshold Effects ◽  
Fluence Rate ◽  
Motion Pattern ◽  
Response Frequency ◽  
Swimming Motion ◽  
Stentor Coeruleus ◽  
Prior Adaptation

Suspensions of Stentor coeruleus were illuminated with a white light (tungsten) source after prior adaptation to cool-white fluorescent light. The cells, with such overall illumination, exhibited a marked step-up response characterized by periodic interruptions of the forward left spiral swimming motion pattern. The interrupted motion type was persistent and the result of a light-dependent reversal of the membranellar ciliary system of the cell. The overall frequency of responses and the duration of the responses increased (from threshold effects at 14 W/m2) as a function of fluence rate (tested up to 158 W/m2; 300–1100 nm). The response frequency changed from 5 to 8 responses/s, while the overall response duration increased from 0.81 to 2.9 s. Key words: Stentor coeruleus, photosensory response, ciliate.

Control of Fatty Acid and Lipid Biosynthesis in Euglena gracilis by Ammonia, Light and DCMU

1972 ◽  
Vol 27 (1) ◽  
pp. 53-61 ◽  
Author(s):  
P. Pohl ◽  
H. Wagner
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
White Light ◽  
Euglena Gracilis ◽  
Fatty Acid Biosynthesis ◽  
Neutral Lipids ◽  
Fluorescent Light ◽  
Low Levels ◽  
High Concentrations ◽  
Monogalactosyl Diglyceride

When Euglena gracilis was grown under white (fluorescent) light in media containing high concentrations of ammonium chloride (more than 0.005%), the main lipids synthesized were monogalactosyl diglyceride, digalactosyl diglyceride, phosphatidyl glycerol, sulfolipid and the all cis △7,10-16:2, △7,10,13-16:3, △4,7,10,13-16:4, △9,12-18:2 and △9,12,15-18:3 fatty acids. At low levels of ammonium (less than 0.002%) these compounds were produced only in small amounts, while neutral lipids, phosphatidyl choline, phosphatidyl ethanolamine and the 14:0, 16:0 and 16:1 fatty acids predominated.When Euglena gracilis was grown in white light in the presence of dichlorophenyldimethylurea (DCMU) or in the dark, fatty acid and lipid biosyntheses followed the same pattern as in white light at low levels of ammonium. Similar results were obtained when nitrate served as the only nitrogen source in the light and in the dark.The results indicate that in Euglena gracilis there are a light independent and a light and ammonium dependent pathway of fatty acid biosynthesis. Both pathways seem to be in association with specific lipids.

scholarly journals Electrophotocatalytic diamination of vicinal C–H bonds

Science ◽  
2021 ◽  
Vol 371 (6529) ◽  
pp. 620-626 ◽  
Author(s):  
Tao Shen ◽  
Tristan H. Lambert
Keyword(s):  
Nitrogen Source ◽  
Anodic Oxidation ◽  
White Light ◽  
Molecular Hydrogen ◽  
Stable Radical ◽  
Maximum Absorption ◽  
Fluorescent Light ◽  
Cathodic Reaction

The conversion of unactivated carbon-hydrogen (C–H) bonds to carbon–nitrogen (C–N) bonds is a highly valued transformation. Existing strategies typically accomplish such reactions at only a single C–H site because the first derivatization diminishes the reactivity of surrounding C–H bonds. Here, we show that alkylated arenes can undergo vicinal C–H diamination reactions to form 1,2-diamine derivatives through an electrophotocatalytic strategy, using acetonitrile as both solvent and nitrogen source. The reaction is catalyzed by a trisaminocyclopropenium (TAC) ion, which undergoes anodic oxidation to furnish a stable radical dication while the cathodic reaction reduces protons to molecular hydrogen. Irradiation of the TAC radical dication (wavelength of maximum absorption of 450 to 550 nanometers) with a white-light compact fluorescent light generates a strongly oxidizing photoexcited intermediate. Depending on the electrolyte used, either 3,4-dihydroimidazole or aziridine products are obtained.

scholarly journals Effect of colour of light on the opening of inflorescence buds and post-harvest longevity of pot chrysanthemums (Chrysanthemum × grandiflorum (Ramat.) Kitam)

2012 ◽  
Vol 64 (3) ◽  
pp. 13-18 ◽  
Author(s):  
Marek Jerzy ◽  
Piotr Zakrzewski ◽  
Anita Schroeter-Zakrzewska
Keyword(s):  
Blue Light ◽  
Significant Influence ◽  
White Light ◽  
Red Light ◽  
Green Light ◽  
Fluorescent Light ◽  
Yellow Light ◽  
Post Harvest ◽  
Growth Room

The pot cultivar of <i>Chrysanthemum</i> × <i>grandiflorum</i> 'Leticia Time Yellow' was cultivated and stored in a growth room under fluorescent light of white, blue, green, yellow and red colour. Quantum irradiance was 30 μmol · m<sup>-2</sup> × s<sup>-1</sup>. The colour of light exerted a significant influence on the opening of closed inflorescence buds and on post-harvest longevity of pot chrysanthemums grown earlier in an unheated plastic tunnel. Under florescent lamps emitting blue light at a wavelength of 400-580 nm, inflorescence buds opened and coloured the earliest. The number of developed flower heads was the greatest under blue and white light. Flower heads developing in blue light were bigger than flower heads developing in white and green light. In red light at a wavelength of 600-700 nm, plants flowered latest and they produced the smallest flower heads. Post-harvest longevity was preserved longest in chrysanthemums kept under blue, white and green light. In red and yellow light, the flowers were overblown earliest.

The Effects of Light and Temperature on Yellow Nutsedge (Cyperus esculentus) Basal-Bulb Formation

Weed Science ◽  
1983 ◽  
Vol 31 (2) ◽  
pp. 148-152 ◽  
Author(s):  
E. W. Stoller ◽  
Joseph T. Woolley
Keyword(s):  
White Light ◽  
Red Light ◽  
Fluorescent Light ◽  
Cyperus Esculentus ◽  
Light Responses ◽  
Yellow Nutsedge ◽  
Bulb Formation ◽  
Basal Bulb ◽  
Alternating Temperature

Investigations were conducted to determine whether light, temperature, or their interaction stimulated primary basal-bulb formation on underground stems of yellow nutsedge (Cyperus esculentusL.) seedlings grown from tubers. Basal-bulb formation results when internodes shorten and leaves lengthen. When seedlings were grown without medium around the underground shoots, a temperature alternation of 10C stimulated basal-bulb formation; light did not affect the process. When seedlings were grown with medium around the underground shoots, either light or alternating temperature stimulated basal-bulb formation. Nine colors of light gave the same stimulus as white (fluorescent) light. Phytochrome did not appear to be the photoreceptor for the stimulus, as both red and far-red light responses were identical to that of white light.

Response Initiation and Response Termination: Analysis of Effects of Punishment and Escape Contingencies

1965 ◽  
Vol 16 (2) ◽  
pp. 569-575 ◽  
Author(s):  
Harold Leitenberg
Keyword(s):  
Escape Response ◽  
Aversive Stimulus ◽  
Bright Light ◽  
Response Duration ◽  
Operant Response ◽  
Response Frequency ◽  
Response Initiation ◽  
Termination Analysis ◽  
Large Platform

Response frequency and response duration were manipulated in opposite directions through appropriate arrangement of punishment and escape contingencies. The experiment demonstrated that the frequency of a non-reinforced operant response could be more effectively suppressed by punishment in one group of rats than in another, even though the former group continued to take a longer time to terminate the response once it had been made. Bright light was the aversive stimulus, depression of a large platform was the response punished, and release of the platform was the escape response.

Absence of Isomerization of Retinyl Palmitate, Retinol, and Retinal in Chlorinated and Nonchlorinated Solvents Under Gold Light

1986 ◽  
Vol 69 (1) ◽  
pp. 50-55 ◽  
Author(s):  
Gary M Landers ◽  
James A Olson
Keyword(s):  
White Light ◽  
Chloride Solution ◽  
Methylene Chloride ◽  
Chloroform Solution ◽  
Retinyl Palmitate ◽  
Free Radical Scavengers ◽  
Fluorescent Light ◽  
Methylene Chloride Solution ◽  
Cis Isomer ◽  
Hexane Solution

Abstract Purified solutions of all-trans retinyl palmitate, retinol, and retinaldehyde in chloroform, methylene chloride, or hexane were exposed to white light or gold fluorescent light or were kept in the dark, and the resulting isomer distributions were determined by LC (liquid chromatography). No significant isomerization of any of the retinoids occurred either in the dark or on exposure to gold light in any of the solvents tested. However, a large amount of the 9-cis isomer and only much smaller amounts of other cis isomers were produced when retinol or retinyl palmitate in chloroform or methylene chloride solution was exposed to white light. The isomerization pattern of retinyl palmitate in chloroform was not altered by the addition of free-radical scavengers, addition of an organic base, or substitution of deuterochloroform for chloroform as solvent. Use of other polar solvents such as tetrahydrofuran, acetone, or methanol produced isomer distributions similar to those obtained in chloroform solution. Retinol and retinyl palmitate in hexane solution, on exposure to white light, were isomerized much less extensively than in chloroform or methylene chloride and produced a significant amount of the 13-cis, as well as the 9-cis, isomer. Isomerization of retinaldehyde in chloroform or in methylene chloride solution under white light yielded 13-cis, 11-cis, 9-cis, and 7-cis isomers, in order of decreasing amount, whereas in hexane solution, only the 13-cis and 9-cis isomers were produced in significant quantity

scholarly journals Light in intermediate acclimatization of in vitro germinated seedlings of Dendrobium phalaenopsis Deang Suree

2015 ◽  
Vol 45 (2) ◽  
pp. 231-237 ◽  
Author(s):  
José Carlos Sorgato ◽  
Yara Brito Chaim Jardim Rosa ◽  
Jackeline Schultz Soares ◽  
Camila Soares Rosa Lemes ◽  
Gisele Garcia de Sousa
Keyword(s):  
White Light ◽  
Root Length ◽  
Red Light ◽  
Fluorescent Light ◽  
Fresh Weight ◽  
Survival Percentage ◽  
Number Of Leaves ◽  
Weight Number ◽  
Better Than

The success in micropropagation of Dendrobium phalaenopsis Deang Suree is high, but when transplanted into the greenhouse, their survival is minimal. To increase survival in production in the present study it was evaluated the effect of intermediate acclimatization for 30 days in a grow room utilizing the following luminosity conditions: 1- white fluorescent light (B) (18.9µmol m-2 s-1); 2- white fluorescent light + red fluorescent light (GRO-LUX(r)) (BV) (14.85µmol m-2 s-1); 3- red fluorescent light (GRO-LUX(r)) (V) (9.45µmol m-2 s-1) and the control plants were accommodated directly in a greenhouse (162.0µmol m-2 s-1). After this the leaves were characterized anatomically and the plants transferred to the control greenhouse. It was evaluated survival percentage and final number of roots, and calculated the relations between the final and initial values of fresh weight, number of leaves, length and diameter of the largest pseudo bulb, number of pseudo bulbs and longest root length. Only plants submitted to red light, were statistically better than the control in relation to the survival percentage and in relation to fresh weight, while the control showed a higher number of roots that plants acclimatized in this luminosity conditions. Intermediate acclimatization, using red light or red + white light, is recommended for D. phalaenopsis Deang Suree.

FeXIV Line Emission Polarization of the July 11, 1991 Solar Corona

1994 ◽  
Vol 144 ◽  
pp. 541-547
Author(s):  
J. Sýkora ◽  
J. Rybák ◽  
P. Ambrož
Keyword(s):  
High Resolution ◽  
Solar Corona ◽  
Emission Line ◽  
Solar Eclipse ◽  
White Light ◽  
Preliminary Analysis ◽  
Line Emission ◽  
Total Solar Eclipse ◽  
Degree Of Polarization ◽  
High Resolution Images

AbstractHigh resolution images, obtained during July 11, 1991 total solar eclipse, allowed us to estimate the degree of solar corona polarization in the light of FeXIV 530.3 nm emission line and in the white light, as well. Very preliminary analysis reveals remarkable differences in the degree of polarization for both sets of data, particularly as for level of polarization and its distribution around the Sun’s limb.

White-Light Coronal Structures: Streamers and CMEs

1994 ◽  
Vol 144 ◽  
pp. 82
Author(s):  
E. Hildner
Keyword(s):  
Emission Line ◽  
Electron Density ◽  
White Light ◽  
Coronal Mass Ejections ◽  
X Rays ◽  
Solar Cycles ◽  
Temperature Function ◽  
X Ray ◽  
Eclipse Observations ◽  
Coronal Structures

AbstractOver the last twenty years, orbiting coronagraphs have vastly increased the amount of observational material for the whitelight corona. Spanning almost two solar cycles, and augmented by ground-based K-coronameter, emission-line, and eclipse observations, these data allow us to assess,inter alia: the typical and atypical behavior of the corona; how the corona evolves on time scales from minutes to a decade; and (in some respects) the relation between photospheric, coronal, and interplanetary features. This talk will review recent results on these three topics. A remark or two will attempt to relate the whitelight corona between 1.5 and 6 R⊙to the corona seen at lower altitudes in soft X-rays (e.g., with Yohkoh). The whitelight emission depends only on integrated electron density independent of temperature, whereas the soft X-ray emission depends upon the integral of electron density squared times a temperature function. The properties of coronal mass ejections (CMEs) will be reviewed briefly and their relationships to other solar and interplanetary phenomena will be noted.

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