scholarly journals Effect of High Light Intensity Bleaching Protocol versus Descending Light Intensities Bleaching Protocol on Post Bleaching Teeth Sensitivity: A Randomized Clinical Trial

2019 ◽  
Vol 7 (13) ◽  
pp. 2173-2181
Author(s):  
Shadwa H. Kabil ◽  
Mohamed F. Haridy ◽  
Mohamed R. Farid
Keyword(s):  
Light Intensity ◽  
Colour Change ◽  
High Light Intensity ◽  
High Light ◽  
Parametric Test ◽  
Whitney Test ◽  
Anterior Teeth ◽  
Mann Whitney Test ◽  
Light Intensities ◽  
Shade Guide

AIM: The study aimed to compare teeth sensitivity and shade after bleaching protocol with descending different light intensities versus bleaching protocol with the same high light intensity. MATERIAL AND METHODS: Sample size was twenty-four patients. Each group consisted of twelve patients. Group, I patients received bleaching protocol of descending different light intensities. Group II patients received bleaching protocol with the same high light intensity; both groups used the same home bleaching gel kit for seven days according to manufacturer instructions and protocol. Baseline records were digital photographs, teeth sensitivity and teeth shade for 12 anterior teeth. Teeth sensitivity was assessed using five points verbal rating scale and Standardized 100 mm Visual analogue scale after 1 day, after 2 days and after 1 week. Teeth shades for twelve anterior teeth were recorded by VITA Easy Shade V (VITA Zahnfabrik H. Rauter GmbH & Co. KG, Germany) after 1 week by VITA Easy Shade V. Mann-Whitney test (non-parametric test, 2 independent samples) was used to compare teeth sensitivity between both bleaching protocols at each period. A paired t-test (parametric test, 2 related samples) was performed to compare the colour change in shade guide units (SGU) and ∆E values within high light intensity bleaching protocol. While Wilcoxon Signed-Rank test (non-parametric test, 2 related samples) was used to compare colour change light intensities bleaching protocol. Comparison of bleaching effectiveness (∆SGU and ∆Ediff) between both bleaching protocols was performed by the Mann-Whitney test. RESULTS: Descending light intensities protocol showed a lower teeth sensitivity than high light intensity protocol after 1 and 2 days. There was no teeth sensitivity reported at 1-week post-bleaching. Regarding the teeth shade, descending light intensities protocol had a little higher effect on colour change in shade guide units (SGU) than high light intensity protocol effect. Both bleaching protocols showed there was no significant difference in ∆SGU recorded after bleaching between high and descending light intensities protocols. CONCLUSION: Descending different light intensities protocol showed a lower teeth sensitivity than high same light intensity protocol. Descending light intensities protocol had a little higher effect on colour change in shade guide units (SGU) than high light intensity protocol effect.

scholarly journals Light intensity regulates phototaxis, foraging and righting behaviors of the sea urchin Strongylocentrotus intermedius

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e8001 ◽  
Author(s):  
Jiangnan Sun ◽  
Xiaomei Chi ◽  
Mingfang Yang ◽  
Jingyun Ding ◽  
Dongtao Shi ◽  
...  
Keyword(s):  
Light Intensity ◽  
Foraging Behavior ◽  
Sea Urchins ◽  
High Light Intensity ◽  
High Light ◽  
Strongylocentrotus Intermedius ◽  
Low Light ◽  
Low Light Intensity ◽  
Light Intensities ◽  
Significant Difference

Small sea urchins Strongylocentrotus intermedius (1–2 cm of test diameter) are exposed to different environments of light intensities after being reseeded to the sea bottom. With little information available about the behavioral responses of S. intermedius to different light intensities in the environment, we carried out an investigation on how S. intermedius is affected by three light intensity environments in terms of phototaxis, foraging and righting behaviors. They were no light (zero lx), low light intensity (24–209 lx) and high light intensity (252–2,280 lx). Light intensity had obvious different effects on phototaxis. In low light intensity, sea urchins moved more and spent significantly more time at the higher intensity (69–209 lx) (P = 0.046). S. intermedius in high light intensity, in contrast, spent significantly more time at lower intensity (252–690 lx) (P = 0.005). Unexpectedly, no significant difference of movement (average velocity and total distance covered) was found among the three light intensities (P > 0.05). Foraging behavior of S. intermedius was significantly different among the light intensities. In the no light environment, only three of ten S. intermedius found food within 7 min. In low light intensity, nine of 10 sea urchins showed successful foraging behavior to the food placed at 209 lx, which was significantly higher than the ratio of the number (two of 10) when food was placed at 24 lx (P = 0.005). In the high light intensity, in contrast, significantly less sea urchins (three of 10) found food placed at the higher light intensity (2,280 lx) compared with the lower light intensity (252 lx) (10/10, P = 0.003). Furthermore, S. intermedius showed significantly longer righting response time in the high light intensity compared with both no light (P = 0.001) and low light intensity (P = 0.031). No significant difference was found in righting behavior between no light and low light intensity (P = 0.892). The present study indicates that light intensity significantly affects phototaxis, foraging and righting behaviors of S. intermedius and that ~200 lx might be the appropriate light intensity for reseeding small S. intermedius.

scholarly journals Cellular Bioenergetics in Spirulina platensis towards Growth and Phycocyanin Production Under Different Photon Flux Densities Using the Modified Zarrouk’s Medium

2021 ◽  
Vol 9 (1) ◽  
pp. 28-34
Author(s):  
Anyway Chofamba
Keyword(s):  
Light Intensity ◽  
Chlorophyll Content ◽  
Spirulina Platensis ◽  
Low Cost ◽  
Biomass Accumulation ◽  
High Light Intensity ◽  
High Light ◽  
Photon Flux ◽  
Market Demand ◽  
Light Intensities

From all the pigments found in Spirulina platensis, phycocyanin has been found to have a diverse application in various fields, and has a high market demand, calling for a need to increase production and easy isolation methods. In general, phycocyanin production in cells depends on the light conditions, among other factors during the cultivation period. The focus of this study was to look at the effect of different light intensities on phycocyanin production in Spirulina platensis. Other cellular biochemical parameters, including chlorophyll content and protein, were explored under the different treatments. An experimental design containing 4 different light intensities of 20, 150, 300 and 600 μmol photons m2/s was administered with 3 replicates. The results obtained from the study showed that high phycocyanin content was obtained from a low light intensity treatment. Chlorophyll results were a bit in contrary to the results obtained for phycocyanin, with high chlorophyll content obtained in high light intensity treatments. Protein and biomass accumulation also followed the same trend, where they were observed to be higher in high light intensities, with the maximum biomass achieved at 600 μmol photons m2/s and maximum protein content achieved at 300 μmol photons m2/s. Due to the commercial potential of phycocyanin to humans, its low cost downstream cultivation and processing of Spirulina platensis will be of economic advantage to the relevant stakeholders to fulfil the rampant demands and affordability of the blue phycocyanin pigment to both first and third World countries, hence the need of producing phycocyanin using the modified Zarouk’s media which has cheaper if not affordable ingredients.

scholarly journals METABOLIC CONDITIONS IN CHLORELLA

1948 ◽  
Vol 32 (1) ◽  
pp. 103-110 ◽  
Author(s):  
Jack Myers ◽  
Marian Cramer
Keyword(s):  
Light Intensity ◽  
Nitrogen Assimilation ◽  
Nitrogen Deficiency ◽  
Chlorella Pyrenoidosa ◽  
High Light Intensity ◽  
High Light ◽  
Overflow Metabolism ◽  
High Co2 ◽  
Light Intensities ◽  
N Assimilation

1. The effect of nitrate reduction and assimilation on the CO2/O2 quotient of gas exchange has been used as an index of the relative rates of carbon and nitrogen assimilation in Chlorella pyrenoidosa. Changes in over-all metabolism induced by starvation, high light intensity, and nitrogen deficiency have been studied in comparison with the metabolism of cells growing at light-limiting intensities. 2. Starvation, which results in depletion of carbohydrate reserves, gives rise to a high CO2/O2 quotient (∼0.9) during photosynthesis and, therefore, a high C/N assimilation ratio. Starved cells apparently restore their normal C/N ratio before becoming growing cells. 3. Under photosynthesis-saturating light intensities cells show the high CO2/O2 quotient (0.9) indicative of a high C/N assimilation ratio. Return to low light intensities is followed by the abnormally low CO2/O2 quotient (∼0.4) of a low C/N assimilation ratio. High light intensity apparently gives rise to a condition of a limiting rate of nitrogen assimilation and to an overflow metabolism analogous to that found in other microorganisms. 4. Nitrogen deficiency leads to a completely carbohydrate metabolism in short time experiments and makes still more pronounced the effects characteristic of high light intensity alone. 5. Considerations of nutritional economy sustain the experimental evidence in establishing the metabolism of cells growing under light-limiting intensities as the normal or reference metabolic condition in Chlorella.

Factors affecting growith and distribution of kauri (Agathis australis Salisb.) I. Effect of light on the establishment of Kaura and of Phyllocladus trichomanoides D.Don

1959 ◽  
Vol 7 (3) ◽  
pp. 252 ◽  
Author(s):  
RL Bieleski
Keyword(s):  
Light Intensity ◽  
Frequency Distribution ◽  
High Light Intensity ◽  
High Light ◽  
Low Light ◽  
Factors Affecting ◽  
Light Intensities ◽  
Seedling Distribution ◽  
Conifer Seedling ◽  
Effect Of Light

A method for determining the effect of light on seedling distribution in the field is described. It can be applied when seedling frequencies are as low as 1/m2. The frequency distribution of light intensities occupied by seedlings in a quadrat is compared with the frequency distribution of light intensities measured on a grid in the quadrat. This method was used to study the effect of light intensity on the establishment of two New Zealand gymnosperms, kauri (Agathis australis) and Phyllocladus trichomanoides, in the nursery community, a semimature Leptospermum scoparium – L. ericoides associes. Kauri and Phyllocladus did not occur at light intensities below 0.015 and 0.018 full daylight respectively. This limitation appeared to be due to the low light intensity presumably limiting photosynthesis. Kauri, but not Phyllocladus, also showed a high light intensity limit, at 0.30 full daylight, above which seedlings did not establish. Reasons are given for considering this as an indirect effect, probably through related solar heating affecting soil temperature or moisture. The optimal light intensity for kauri and Phyllocladus seedling establishment was close to the modal light intensity under the Leptospermum community: Leptospermum spp. were incapable of regenerating under their own cover. These two reasons appear to explain the suitability of the Leptospermum community as a nurse crop for the two conifer seedling species.

Selection for light preference during ovipositing in Drosophila pseudoobscura

1983 ◽  
Vol 25 (5) ◽  
pp. 446-449 ◽  
Author(s):  
Marvin B. Seiger ◽  
Amelia Broach Sanner
Keyword(s):  
Light Intensity ◽  
Genetic Variability ◽  
High Light Intensity ◽  
High Light ◽  
Drosophila Pseudoobscura ◽  
Low Light ◽  
Original Population ◽  
Low Light Intensity ◽  
Light Intensities ◽  
Light Preference

Selection was carried out on a population of Drosophila pseudoobscura to obtain lines preferring high-light intensity or low-light intensity during oviposition. This species is generally characterized as preferring low-light intensities. It was possible to select for increased preference for high-light intensity, but not for low-light intensity during oviposition. However, additive genetic variability exists in preferences for both high- and low-light intensities. The original population was probably operating at a photonegative extreme for oviposition, yet maintained enough genetic variability to permit selection toward a photopositive preference.

Climate, nitrogen and grass. 3. Some effects of light intensity on nitrogen metabolism.

1971 ◽  
Vol 19 (3) ◽  
pp. 184-188
Author(s):  
B. Deinum
Keyword(s):  
Light Intensity ◽  
Nitrogen Metabolism ◽  
Perennial Ryegrass ◽  
High Light Intensity ◽  
High Light ◽  
Water Soluble ◽  
Soluble Carbohydrates ◽  
Nitrate Content ◽  
Light Intensities ◽  
Water Soluble Carbohydrates

Between 18 May and 29 June 1966, a 2-year-old sward of perennial ryegrass was grown at normal (390), low (88) or high (711 cal/cm2 day) light intensity and given 20-160, 40-320 and 80-360 kg N/ha at the 3 light intensities, respectively. At low rates of N, high light intensity exhausted the nitrate reserves of perennial ryegrass, diminished the CP content, but greatly increased the percentage of water-soluble carbohydrates. With high N, high light intensity decreased nitrate content but increased both CP and water-soluble-carbohhdrate content. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Regreening of involucral leaves of female Leucadendron (Proteaceae) after flowering

2010 ◽  
Vol 58 (7) ◽  
pp. 586 ◽  
Author(s):  
M. Schmeisser ◽  
W. J. Steyn ◽  
G. Jacobs
Keyword(s):  
Light Intensity ◽  
Photosynthetic Pigments ◽  
Colour Change ◽  
Complete Removal ◽  
High Light Intensity ◽  
High Light ◽  
Growth Chamber ◽  
Full Bloom ◽  
Yellow Colour ◽  
Plastid Envelope

Involucral leaves of Leucadendron have the remarkable ability to turn yellow upon flowering and regreen naturally as the florets of the inflorescence wilt. This colour change results from degradation of chlorophyll and to a lesser degree carotenoids, resulting in the unmasking of yellow colour. Chlorophyll levels were restored upon regreening. Degreening coincided with the complete dismantling of the thylakoid system, while keeping the outer plastid envelope intact. Regreening resulted from the complete redifferentiation of these gerontoplast-like plastids into functional chloroplasts. The colour change was directly linked to the development of the inflorescence. Complete removal of the inflorescence before flowering prevented the colour change while removal at full bloom, when involucral leaves were yellow, resulted in significantly faster regreening. This designates the inflorescence or florets as the possible origin of the colour change trigger and suggests that the colour change is involved with attraction of pollinators. Degreening and regreening also took place in a growth chamber under continuous high light intensity. Therefore neither pollination nor the presence of roots is required for regreening. It appears that colour change in Leucadendron results from a well-regulated degradation and subsequent synthesis of photosynthetic pigments.

scholarly journals Dynamic regulation of anthocyanin biosynthesis at different light intensities by the BT2-TCP46-MYB1 module in apple

2020 ◽  
Vol 71 (10) ◽  
pp. 3094-3109 ◽  
Author(s):  
Jian-Ping An ◽  
Ya-Jing Liu ◽  
Xiao-Wei Zhang ◽  
Si-Qi Bi ◽  
Xiao-Fei Wang ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Light Intensity ◽  
Target Genes ◽  
Anthocyanin Biosynthesis ◽  
High Light Intensity ◽  
High Light ◽  
26S Proteasome ◽  
Dynamic Regulation ◽  
Light Intensities ◽  
Regulatory Module

Abstract Teosinte branched1/cycloidea/proliferating (TCP) transcription factors play a broad role in plant growth and development, but their involvement in the regulation of anthocyanin biosynthesis is currently unclear. In this study, anthocyanin biosynthesis induced by different light intensities in apple (Malus domestica) was found to be largely dependent on the functions of the MdMYB1 and MdTCP46 transcription factors. The expression of MdTCP46 was responsive to high light intensity, and under these conditions it promoted anthocyanin biosynthesis by direct interactions with MdMYB1 that enhanced the binding of the latter to its target genes. MdTCP46 also interacted with a bric-a-brac/tramtrack/broad (BTB) protein, MdBT2, that is responsive to high light intensity, which ubiquitinated MdTCP46 and mediated its degradation via the 26S proteasome pathway. Our results demonstrate that the dynamic regulatory module MdBT2-MdTCP46-MdMYB1 plays a key role in modulating anthocyanin biosynthesis at different light intensities in apple, and provides new insights into the post-transcriptional regulation of TCP proteins.

scholarly journals Analysis of β-d-glucan biosynthetic genes in oat reveals glucan synthesis regulation by light

2020 ◽  
Author(s):  
Jing Zhang ◽  
Lin Yan ◽  
Minxuan Liu ◽  
Ganggang Guo ◽  
Bing Wu
Keyword(s):  
Light Intensity ◽  
Growth Control ◽  
Gene Promoter ◽  
Gene Families ◽  
Gus Expression ◽  
High Light Intensity ◽  
High Light ◽  
Synthesis Mechanism ◽  
Light Intensities ◽  
Glucan Synthesis

Abstract Background and Aims Oat (Avena sativa) has human health benefits when consumed as a whole-grain food, attributed to the high content of (1,3;1,4)-β-d-glucan (mixed-linkage glucan [MLG]), but little is known about the synthase genes and synthesis mechanism of MLG polysaccharides in this species. Methods The concentration of oat MLGs under different light intensities was measured by a standard enzymatic approach and further verified by immunoelectron microscopy. The effect of light intensity on MLG synthase genes was examined by RT–qPCR and western blot analyses. The pattern of expression directed by the promoter of the oat MLG synthase gene was also investigated by histochemical β-glucuronidase (GUS) analysis. Key Results The oat orthologues of genes implicated in the synthesis of MLG in other cereals, including cellulose synthase-like (Csl) F, H and J gene families, were defined. Transcript profiling of these genes across oat tissues indicated that AsCslF6 transcripts dominated. Under high light intensities, the expression of AsCslF6, a major isoform of the MLG synthase genes, increased to >30 % of the dark growth control. The amount of MLG in oat rose from 0.07 to 1.06 % with increased light intensity. Histochemical tests showed that the AsCslF6 gene promoter preferentially directs GUS expression under high light intensity conditions. Conclusions Oat MLG synthesis is regulated by light. High light intensity upregulates the expression of the MLG synthase AsCslF6 gene, leading to an increase in the amount of MLG in oat leaves.

Characteristics of Photosynthesis in Different Wheat Cultivars under High Light Intensity and High Temperature Stresses

2009 ◽  
Vol 34 (12) ◽  
pp. 2196-2201 ◽  
Author(s):  
Xue-Li QI ◽  
Lin HU ◽  
Hai-Bin DONG ◽  
Lei ZHANG ◽  
Gen-Song WANG ◽  
...  
Keyword(s):  
High Temperature ◽  
Light Intensity ◽  
High Light Intensity ◽  
High Light ◽  
Wheat Cultivars ◽  
Temperature Stresses
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