scholarly journals A Persistent Daily Rhythm in Photosynthesis

1961 ◽  
Vol 45 (1) ◽  
pp. 69-76 ◽  
Author(s):  
J. Woodland Hastings ◽  
Lazarus Astrachan ◽  
Beatrice M. Sweeney
Keyword(s):  
Cell Division ◽  
Diurnal Rhythm ◽  
Maximum Rate ◽  
Photosynthetic Capacity ◽  
Bright Light ◽  
Light Period ◽  
Daily Rhythm ◽  
Single Mechanism ◽  
Rate Of Photosynthesis ◽  
Dim Light

The luminescent marine dinoflagellate, Gonyaulax polyedra, exhibits a diurnal rhythm in the rate of photosynthesis and photosynthetic capacity measured by incorporation of C14O2, at different times of day. With cultures grown on alternating light and dark periods of 12 hours each, the maximum rate is at the 8th hour of the light period. Cultures transferred from day-night conditions to continuous dim light continue to show the rhythm of photosynthetic capacity (activity measured in bright light) but not of photosynthesis (activity measured in existing dim light). Cultures transferred to continuous bright light, however, do not show any rhythm. Several other properties of the photosynthetic rhythm are similar to those of previously reported rhythms of luminescence and cell division. This similarity suggests that a single mechanism regulates the various rhythms.

scholarly journals Circadian Rhythm and Stress Response in Droppings ofSerinus canaria

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Maura Turriani ◽  
Nicola Bernabò ◽  
Barbara Barboni ◽  
Gianluca Todisco ◽  
Luigi Montini ◽  
...  
Keyword(s):  
Circadian Rhythm ◽  
Stress Response ◽  
Enzyme Immunoassay ◽  
Light Period ◽  
Daily Rhythm ◽  
Fecal Excretion ◽  
Dark Phase ◽  
Light Cycle ◽  
Serinus Canaria ◽  
Commercial Enzyme Immunoassay

Serinus canariais a widespread domestic ornamental songbird, whose limited knowledge of biology make compelling studies aimed to monitor stress. Here, a commercial enzyme immunoassay was adopted to measure immunoreactive corticosterone (CORT) in singleSerinus canariadropping sample, to monitor the daily fecal excretion of CORT in birds bred singly or in-group and to detect the effect promoted by aviary or small transport cage restraint. A robust daily rhythm of CORT was recorded in animals held on short-day light cycle, independent of bred conditions (single or group), which persisted when space availability was modified in single bred animal (transfer in aviary and transport cages). By contrast, a significant change in CORT excretion was recorded when group bred animals are restrained in a smaller cage. The daily rhythm in CORT excretion in response to manipulation showed the greatest response at the beginning of the light period, followed by the absence of the peak usually recorded at the end of the dark phase. These data indicated that EIA could be used as a reliable noninvasive approach to monitor the stress induced by restraint conditions inSerinus canaria.

If You’re Happy and You Know it Stay Alert: The Effects of Lighting on Vigilance Performance and Affective State

2021 ◽  
Vol 65 (1) ◽  
pp. 854-858
Author(s):  
Lauren E. Monroe ◽  
Samantha L. Smith
Keyword(s):  
Affective State ◽  
Light Condition ◽  
Bright Light ◽  
Extended Period ◽  
Light Therapy ◽  
Speed Of Information Processing ◽  
Attention Tasks ◽  
High Workload ◽  
Dim Light ◽  
Over Time

Vigilance, or sustained attention tasks involve detecting critical signals, embedded amid more frequent neutral signals, over an extended period of time. A decline in performance, engagement, and arousal over time, as well as high workload and stress, are common outcomes of such tasks. Exposure to broad-spectrum or short wavelength bright light has been found to positively impact alertness, speed of information processing, and mood, but has not been extensively explored in the vigilance domain. The present study explored whether a light therapy lamp could mitigate the negative vigilance outcomes found in both performance and affective state. Results indicated that the therapy light did not prevent a decline in detection of critical signals over time, nor significantly impact workload, sleepiness, or subjective stress state compared to a dim light condition. However, mood questionnaire results suggest that lighting may impact separate constructs of arousal and tiredness, warranting further research.

scholarly journals 0216 Is There a Daily Rhythm in Alcohol Craving and Does It Vary by Circadian Timing?

SLEEP ◽  
2020 ◽  
Vol 43 (Supplement_1) ◽  
pp. A84-A84
Author(s):  
G Hisler ◽  
S Pedersen ◽  
D Clark ◽  
S Rothenberger ◽  
B Hasler
Keyword(s):  
Individual Differences ◽  
Young Adult ◽  
Daily Rhythm ◽  
Adolescent And Young Adult ◽  
Late Adolescent ◽  
Circadian Timing ◽  
Alcohol Craving ◽  
Time In Bed ◽  
Scant Attention ◽  
Dim Light

Abstract Introduction People with later circadian timing tend to consume more alcohol, potentially due to altered rhythms in when and how much they crave alcohol throughout the day. However, whether circadian factors play a role in alcohol craving has received scant attention. Here, we investigated if the daily rhythm of alcohol craving varied by circadian timing in two independent studies of late adolescent and young adult drinkers. Methods In Study 1, 32 participants (18–22 years of age; 61% female; 69% White) completed momentary reports of alcohol craving five times a day for 14 days. Participants wore wrist actigraphs and completed two in-lab assessments of dim light melatonin onset (DLMO). Average actigraphically-assessed midpoint of sleep on weekends and average DLMO were used as indicators of circadian timing. In Study 2, 231 participants (21–35 years of age; 28% female; 71% White) completed momentary reports of alcohol craving six times a day for 10 days. Average midpoint of self-reported time-in-bed on weekends was used to estimate circadian timing. Results Multilevel cosinor analysis revealed a 24-hour daily rhythm in alcohol craving which was moderated by circadian timing in both studies (p’s<0.05). In both Study 1 and 2, people with later circadian timing had a later timed peak of craving. In Study 1, but not Study 2, later circadian timing predicted a blunted amplitude in craving. Conclusion Findings support a daily rhythm in craving that varies by individual differences in circadian timing. Because craving is an important predictor of future alcohol use, the findings implicate circadian factors as a useful area to advance alcohol research and potentially improve interventions. Support R21AA023209; R01DA044143; K01AA021135; ABMRF/The Foundation for Alcohol Research.

Treatment of Seasonal Affective Disorder with Light in the Evening

1985 ◽  
Vol 147 (4) ◽  
pp. 424-428 ◽  
Author(s):  
Steven P. James ◽  
Thomas A. Wehr ◽  
David A. Sack ◽  
Barbara L. Parry ◽  
Norman E. Rosenthal
Keyword(s):  
Sleep Deprivation ◽  
Affective Disorder ◽  
Seasonal Affective Disorder ◽  
Bright Light ◽  
Early Morning ◽  
Antidepressant Effect ◽  
Comparison Study ◽  
Female Patients ◽  
Dim Light ◽  
Effect Of Light

A cross-over comparison study of exposure, in the evenings only, to bright versus dim light was carried out on nine female patients with seasonal affective disorder. A significant antidepressant effect of the bright lights was shown. No consistent observable effects were produced by the dim lights. These results support earlier studies demonstrating the efficacy of bright light given morning and evening. The antidepressant effect of light is not mediated by sleep deprivation, and the early morning hours are not crucial for a response.

The relationship between ambient lighting conditions, absolute dark-adapted thresholds, and rhodopsin in black and hypopigmented mice

2004 ◽  
Vol 21 (6) ◽  
pp. 925-934 ◽  
Author(s):  
GERARD H. DALY ◽  
JESSICA M. DILEONARDO ◽  
NATALIE R. BALKEMA ◽  
GRANT W. BALKEMA
Keyword(s):  
Bright Light ◽  
Visual Sensitivity ◽  
Segment Length ◽  
Single Strain ◽  
Photoreceptor Layer ◽  
Lighting Conditions ◽  
Ambient Lighting ◽  
Dim Light ◽  
Albino Mice ◽  
The Relationship

Significant variation in absolute dark-adapted thresholds is observed both within and between strains of mice with differing ocular pigmentation levels. Differences in threshold within a single strain are related to the Williams' photostasis effect, that is, photoreceptor rhodopsin levels are dependent upon ambient lighting conditions. To examine threshold differences among strains, we equalized rhodopsin levels by maintaining albino mice (c2J/c2J) at 2 × 10−4 cd/m2 (dim light) and black mice at 2 × 102 cd/m2 (bright light). This resulted in ocular rhodopsin levels for albino mice (albino—dim) of 494 ± 11 pmoles/eye and rhodopsin levels for black mice (black—bright) of 506 ± 25 pmoles/eye. For comparison, rhodopsin levels in black mice maintained in dim light are 586 ± 46 pmoles/eye and 217 ± 46 pmoles/eye in albino mice maintained in bright light. We found similar dark-adapted thresholds (6.38 log cd/m2vs. 6.47 log cd/m2)) in albino and black mice with equivalent rhodopsin determined with a water maze test. This suggests that dark-adapted thresholds are directly related to rhodopsin levels regardless of the level of ocular melanin. The number of photoreceptors, photoreceptor layer thickness, and outer segment length did not differ significantly between albino (dark) and black mice (bright). These results demonstrate that the visual sensitivity defect found in hypopigmented animals is secondary to abnormal rhodopsin regulation and that hypopigmented animals have either an improper input to the photostasis mechanism or that the photostasis mechanism is defective.

Control of Photosynthesis in Amaranthus edulis Mutants with Reduced Amounts of PEP Carboxylase

1997 ◽  
Vol 24 (4) ◽  
pp. 469 ◽  
Author(s):  
Louisa V. Dever ◽  
Karen J. Bailey ◽  
Richard C. Leegood ◽  
Peter J. Lea
Keyword(s):  
Maximum Rate ◽  
Compensatory Mechanism ◽  
Wild Type ◽  
Pep Carboxylase ◽  
Temperature Changes ◽  
Rate Of Photosynthesis ◽  
Lower Maximum ◽  
Fine Adjustment ◽  
Control Coefficients ◽  
Wild Type Control

Mutants of the NAD-ME plant have been created using sodium azide. These contain reduced activities of PEP carboxylase ranging from 5 to 100% of wild-type. Those with greater than 50% of the wild-type PEPC content showed a lower maximum rate of photosynthesis and reduced carboxylation efficiency compared to the wild-type plants. The PEPC from these heterozygotes was less sensitive to malate inhibition than the PEPC of the wild-type plants and also had an increased phosphorylation state. Mutants containing 45 and 49% of wild-type PEPC exhibited a greater Amax than was observed for the 55, 66 and 70% mutants. We postulate that there is a compensatory mechanism that activates PEPC when the PEPC protein is less than 55% of the wild-type. Control coefficients were measured for PEP carboxylase from wild-type and heterozygous (55%) plants. Results suggest that activation of PEPC by phosphorylation and metabolites may be more an ‘on-off’ switch than a means of fine adjustment of PEPC activity in response to varying factors such as PEPC content, CO2 or temperature changes.

FACTORS AFFECTING THE PETT VISUAL TEST FOR VITAMIN A DEFICIENCY

1941 ◽  
Vol 19b (4) ◽  
pp. 99-108
Author(s):  
L. B. Pett ◽  
Marian K. Lipkind
Keyword(s):  
Vitamin A ◽  
Diurnal Rhythm ◽  
Standard Error ◽  
Learning Effect ◽  
Vitamin A Deficiency ◽  
Bright Light ◽  
Visual Test ◽  
Factors Affecting ◽  
Test Room ◽  
The Mean

Under the conditions prescribed for the Pett test, which is described, it has been found that: (i) antecedent light does not affect the median of the three tests usually performed; (ii) no error results from the wearing or not wearing of glasses; (ii) the use of pilocarpine to contract the pupils is not advisable; (iv) some light may be admitted into the test room; (v) the time of exposure to the bright light (30 sec.) is suitable; (vi) repeated tests cause a 'learning' effect so rarely as to be of little concern; (vii) the standard error of the mean is ±1.4 and of the median is ±2.4 sec. Some results are presented suggesting that a diurnal rhythm in the vitamin A content of the blood exists.

Human circadian pacemaker is sensitive to light throughout subjective day without evidence of transients

1997 ◽  
Vol 273 (5) ◽  
pp. R1800-R1809 ◽  
Author(s):  
Megan E. Jewett ◽  
David W. Rimmer ◽  
Jeanne F. Duffy ◽  
Elizabeth B. Klerman ◽  
Richard E. Kronauer ◽  
...  
Keyword(s):  
Steady State ◽  
Response Curve ◽  
Phase Response Curve ◽  
Light Exposure ◽  
Light Stimulus ◽  
Dead Zone ◽  
Bright Light ◽  
Temperature Minimum ◽  
Circadian Pacemaker ◽  
Dim Light

Fifty-six resetting trials were conducted across the subjective day in 43 young men using a three-cycle bright-light (∼10,000 lx) stimulus against a background of very dim light (10–15 lx). The phase-response curve (PRC) to these trials was assessed for the presence of a “dead zone” of photic insensitivity and was compared with another three-cycle PRC that had used a background of ∼150 lx. To assess possible transients after the light stimulus, the trials were divided into 43 steady-state trials, which occurred after several baseline days, and 13 consecutive trials, which occurred immediately after a previous resetting trial. We found that 1) bright light induces phase shifts throughout subjective day with no apparent dead zone; 2) there is no evidence of transients in constant routine assessments of the fitted temperature minimum 1–2 days after completion of the resetting stimulus; and 3) the timing of background room light modulates the resetting response to bright light. These data indicate that the human circadian pacemaker is sensitive to light at virtually all circadian phases, implying that the entire 24-h pattern of light exposure contributes to entrainment.

Some aspects of carbon relations in the barley – Helminthosporium teres complex. II. The effects of infection upon net accumulation of carbon in the tissues

1979 ◽  
Vol 57 (3) ◽  
pp. 208-214 ◽  
Author(s):  
Janet Rowe ◽  
J. Reid
Keyword(s):  
Diurnal Cycle ◽  
Photosynthetic Capacity ◽  
Dark Period ◽  
Light Period ◽  
Complex Ii ◽  
Long Term Experiments ◽  
Ca 50 ◽  
Translocation Experiments

First leaves of seedlings of the barley varieties Parkland (susceptible) and C.I. 5791 (resistant) were inoculated with Helminthosporium teres and the net accumulation of carbon (NA) in such leaves and in the uninoculated second leaves of these plants was examined in long-term experiments. In infected leaves of Parkland, NA in the light period of the diurnal cycle was maintained near the levels of controls even when photosynthetic capacity had decreased by ca. 50%, though NA in the dark period had increased 300–400%. However, neither this carbon nor that entering metabolism via β-carboxylation in the light was sufficient to compensate for the loss of photosynthetic capacity over 24 h. Translocation experiments showed that while infection did not increase the movement of carbon from the uninoculated second to infected first leaves, export of carbon by the first leaves (normally high) was greatly reduced, and this retained photosynthate appeared largely responsible for the maintenance of NA in the infected leaves. NA in the uninoculated second leaves of infected plants was reduced only while these leaves were heavily dependent on the first leaves for photosynthate. In infected leaves of C.I. 5791, though photosynthetic capacity dropped and β-carboxylation increased while the pathogen was developing, there was little effect on NA over 24 h. The implications of the effects of infection on NA are discussed.

Leaf morphology and photosynthetic rate in birch seedlings and stump sprouts

1990 ◽  
Vol 20 (7) ◽  
pp. 952-960 ◽  
Author(s):  
A. Kauppi ◽  
M. Kiviniitty ◽  
A. Ferm
Keyword(s):  
Nitrogen Content ◽  
Shoot Growth ◽  
Photosynthetic Capacity ◽  
Leaf Size ◽  
Growing Season ◽  
Optimum Temperature ◽  
Factors Affecting ◽  
Mesophyll Structure ◽  
Rate Of Photosynthesis ◽  
Seed Origin

Comparisons were made of the leaves of sprout-origin and seed-origin shoots of Betulapubescens Ehrh. and B. pendula Roth grown under constant or varying temperatures. Particular attention was paid to leaf structure and other factors affecting the rate of photosynthesis. Differences in shoot growth, leaf size, mesophyll structure, and chlorophyll and nitrogen content were observed between the sprouts and seedlings of both species over the course of the growing season. Many of these differences were reflected in the photosynthesis measurements. The sprouts of both species appeared to show a better photosynthetic capacity in their first growing season than the seedlings, and they continued their height growth longer into the autumn. A distinct decline in the level of photosynthesis took place during the growing season. The results suggest that perhaps because of their higher chlorophyll and nitrogen content, young sprouts benefit more from the extremes of temperature at the beginning and end of the growing season than seedlings of the same age. The optimum temperature was the same for sprouts and seedlings of both species. Whether the superior photosynthetic capacity of sprouts compared with seedlings is maintained in later years remains to be resolved.

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