Pycnidium production by Botryodiplodia theobromae. I. The relation of light to the induction of pycnidia

1969 ◽  
Vol 47 (7) ◽  
pp. 1153-1156 ◽  
Author(s):  
J. A. Ekundayo ◽  
R. H. Haskins
Keyword(s):  
Light Intensity ◽  
Ultraviolet Radiation ◽  
Exposure Period ◽  
Fluorescent Light ◽  
Botryodiplodia Theobromae ◽  
Continuous Irradiation ◽  
Long Wave ◽  
Light Intensities ◽  
Glass Color ◽  
Color Filters

Cultures of Botryodiplodia theobromae Pat. produced pycnidia abundantly on several media under continuous irradiation with fluorescent light. The fungus did not sporulate when grown in darkness. Irradiation of cultures with a light intensity of 15 foot-candles for 4 days was sufficient to stimulate pycnidial production, but for appreciable sporulation to occur over the same exposure period, higher light intensities are required. Irradiation of cultures through glass color filters showed that long-wave ultraviolet radiation stimulated sporulation.

Inhibition of nighttime melatonin secretion in cattle: threshold light intensity for dairy heifers

2001 ◽  
Vol 81 (1) ◽  
pp. 153-156 ◽  
Author(s):  
T. J. Lawson ◽  
A. D. Kennedy
Keyword(s):  
Light Intensity ◽  
Key Words ◽  
Latin Square ◽  
Exposure Period ◽  
Melatonin Secretion ◽  
Melatonin Concentration ◽  
Dairy Heifers ◽  
Plasma Melatonin ◽  
Light Intensities ◽  
Lower Light

Five pre-pubertal Holstein heifers were exposed for 16 h to a light intensity of 400 lx and thereafter to intensities of 0, 50, 100, 200, or 400 lx for an additional 8 h (5 x 5 Latin square design). Exposure to all intensities inhibited (P < 0.05) melatonin secretion for the initial few hours (of the 8-h exposure period); melatonin concentration subsequently increased, particularly with the lower light intensities. Only the highest light intensity (400 lx) suppressed (P < 0.05) plasma melatonin concentrations for the entire 8-h exposure period. Key words: Threshold, supplemental, light, intensity, inhibition, melatonin, heifer

scholarly journals Effect of chlorophyll biosynthesis-related genes on the leaf color in Hosta (Hosta plantaginea Aschers) and tobacco (Nicotiana tabacum L.)

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Jingying Zhang ◽  
Changhai Sui ◽  
Huimin Liu ◽  
Jinjiao Chen ◽  
Zhilin Han ◽  
...  
Keyword(s):  
Light Intensity ◽  
Antioxidant Capacity ◽  
Aminolevulinic Acid ◽  
Chlorophyll Biosynthesis ◽  
Expression Level ◽  
Virus Induced Gene Silencing ◽  
Leaf Color ◽  
Color Changes ◽  
Light Intensities ◽  
Structure Changes

Abstract Background ‘Regal Splendour’ (Hosta variety) is famous for its multi-color leaves, which are useful resources for exploring chloroplast development and color changes. The expressions of chlorophyll biosynthesis-related genes (HrHEMA, HrPOR and HrCAO) in Hosta have been demonstrated to be associated with leaf color. Herein, we isolated, sequenced, and analyzed HrHEMA, HrPOR and HrCAO genes. Subcellular localization was also performed to determine the location of the corresponding enzymes. After plasmid construction, virus-induced gene silencing (VIGS) was carried out to reduce the expressions of those genes. In addition, HrHEMA-, HrPOR- and HrCAO-overexpressing tobacco plants were made to verify the genes function. Changes of transgenic tobacco were recorded under 2000 lx, 6000 lx and 10,000 lx light intensity. Additionally, the contents of enzyme 5-aminolevulinic acid (5-ALA), porphobilinogen (PBG), chlorophyll a and b (Chla and Chlb), carotenoid (Cxc), superoxide dismutase (SOD), peroxidase (POD), malondialdehyde (MDA), proline (Pro) and catalase (CAT) under different light intensities were evaluated. Results The silencing of HrHEMA, HrPOR and HrCAO genes can induce leaf yellowing and chloroplast structure changes in Hosta. Specifically, leaves of Hosta with HrCAO silencing were the most affected, while those with HrPOR silencing were the least affected. Moreover, all three genes in tobacco were highly expressed, whereas no expression was detected in wild-type (WT). However, the sensitivities of the three genes to different light intensities were different. The highest expression level of HrHEMA and HrPOR was detected under 10,000 lx of illumination, while HrCAO showed the highest expression level under 6000 lx. Lastly, the 5-ALA, Chla, Cxc, SOD, POD, MDA, Pro and CAT contents in different transgenic tobaccos changed significantly under different light intensities. Conclusion The overexpression of these three genes in tobacco enhanced photosynthesis by accumulating chlorophyll content, but the influential level varied under different light intensities. Furthermore, HrHEMA-, HrPOR- and HrCAO- overexpressing in tobacco can enhance the antioxidant capacity of plants to cope with stress under higher light intensity. However, under lower light intensity, the antioxidant capacity was declined in HrHEMA-, HrPOR- and HrCAO- overexpressing tobaccos.

A laboratory study of vertical migration

1955 ◽  
Vol 144 (916) ◽  
pp. 329-354 ◽  
Keyword(s):  
Light Intensity ◽  
Vertical Migration ◽  
Time Course ◽  
Tap Water ◽  
Low Light ◽  
Overhead Light ◽  
Light Intensities ◽  
Orientation Response ◽  
Reduced Light ◽  
Characteristic Maximum

In a tank filled with a suspension of indian ink in tap water, a population of Daphnia magna will undergo a complete cycle of vertical migration when an overhead light source is cycli­cally varied in intensity. A ‘dawn rise’ to the surface at low intensity is followed by the descent of the animals to a characteristic maximum depth. The animals rise to the surface again as the light decreases, and finally show a typical midnight sinking. The light intensities at the level of the animals in this experiment are of the same order as those which have been reported in field observations; the time course of the movement also repeats the natural conditions in the field. The process is independent of the duration of the cycle and is related only to the variation in overhead light intensity. At low light intensity the movement of the animal is determined solely by positive photo-kinesis; the dawn rise is a manifestation of this, and is independent of the direction of the light. At high light intensities there is an orientation response which is superimposed upon an alternating positive (photokinetic) phase and a negative phase during which movement is inhibited. The fully oriented animal shows a special type of positive and negative phototaxis, moving towards the light at reduced light intensities and away from it when the light intensity is increased. In this condition it follows a zone of optimum light intensity with some exactness. Experiments show that an animal in this fully oriented condition will respond to the slow changes of intensity characteristic of the diurnal cycle, while being little affected by tran­sient changes of considerable magnitude.

Sensory Behaviour in Dictyostelium Discoideum Slugs: Phototaxis and Thermotaxis are not Mediated by a Change in Slug Speed

1982 ◽  
Vol 54 (1) ◽  
pp. 329-339
Author(s):  
ELIZABETH SMITH ◽  
PAUL R. FISHER ◽  
WARWICK N. GRANT ◽  
KEITH L. WILLIAMS
Keyword(s):  
Molecular Weight ◽  
Temperature Gradient ◽  
Light Intensity ◽  
Dictyostelium Discoideum ◽  
Low Molecular Weight ◽  
Light Intensities ◽  
Slug Movement

The speed of sustained migration of Dictyostelium discoideum slugs was similar in a temperature gradient and at different light intensities, including a light intensity sufficient to cause significant disorientation of slugs. No change was observed in slug speed in the presence of high levels of Slug Turning Factor (STF), a low molecular weight compound through which phototaxis and thermotaxis are mediated. Thus orientation of D. discoideum slugs is not mediated by a sustained changed in slug speed and we propose that slug movement is not directly coupled to tactic responses. Slug speed depended on the size, age and genotype of slugs as well as the nature of the substratum (charcoal-containing water agar versus water agar).

scholarly journals Effects of light intensity and temperature on Cylindrospermopsis raciborskii (Cyanobacteria) with straight and coiled trichomes: growth rate and morphology

2012 ◽  
Vol 72 (2) ◽  
pp. 343-351 ◽  
Author(s):  
MC. Bittencourt-Oliveira ◽  
B. Buch ◽  
TC. Hereman ◽  
JDT. Arruda-Neto ◽  
AN. Moura ◽  
...  
Keyword(s):  
Growth Rate ◽  
Light Intensity ◽  
Morphological Changes ◽  
Population Control ◽  
Distinct Species ◽  
Cylindrospermopsis Raciborskii ◽  
Climatic Chamber ◽  
Light Intensities ◽  
Different Temperatures ◽  
Lower Temperature

Cylindrospermopsis raciborskii (Woloszynska) Seenayya et Subba Raju (Ordem Nostocales) is one of the most troublesome bloom-forming species in Brazil. Understanding the population dynamics of the different morphotypes of C. raciborskii (straight and coiled) could assist in the prediction of favourable conditions for the proliferation of this potentially toxin-producing species. The aim of the present study was to assess the effects of two different light intensities and temperatures on the growth rate and morphology of the trichomes of the straight and coiled morphotypes. For such, two non-toxin producing strains of C. raciborskii were used - one with a coiled trichome (ITEP31) and another with a straight trichome (ITEP28). The strains were cultured in BG-11 medium in a climatic chamber under controlled conditions. Two light intensities (30 and 90 µmol.m-2.s-1 ) were combined at temperatures of 21 and 31 °C and the growth rate and morphological changes were analysed. The morphotypes responded differently to the different temperatures and light intensities. Both strains exhibited faster growth velocities when submitted to higher light intensity and temperature. The lower temperature and higher luminosity hampered the development of both strains. Variations in cellular morphology and an absence of akinetes in both strains were related to the lower temperature (21 °C). The coiled morphotype demonstrated considerable phenotype plasticity, changing the morphology of trichome throughout its growth curve. Although molecular analysis does not sustain the separation of the morphotypes as distinct species, their different eco-physiological responses should be considered further knowledge of extreme importance for the population control of these potentially toxic organisms.

COMBINATION AND DISPROPORTIONATION OF ETHYL RADICALS: INFLUENCE OF THE REACTION H+C2H5 = C2H6

1955 ◽  
Vol 33 (5) ◽  
pp. 821-829 ◽  
Author(s):  
Moyra J. Smith ◽  
Patricia M. Beatty ◽  
J. A. Pinder ◽  
D. J. Le Roy
Keyword(s):  
Light Intensity ◽  
Excellent Agreement ◽  
Mercury Concentration ◽  
Rate Constants ◽  
Room Temperature ◽  
Low Light ◽  
Ethylene Concentration ◽  
Light Intensities ◽  
Ethyl Radicals ◽  
Hydrogenation Of Ethylene

The mercury (3P1) photosensitized hydrogenation of ethylene has been studied at room temperature as a function of ethylene concentration, mercury concentration, and light intensity. In addition to combination and disproportionation, ethyl radicals have been shown to take part in the reaction[Formula: see text]The conditions favoring this reaction have been established and anomalous values previously found for the ratio of ethane to butane have been explained. The value obtained for the ratio of the rate constants for the disproportionation and combination of ethyl radicals, 0.15 ±.01, is in excellent agreement with the values obtained by other methods. Hexane formation is of some importance at low light intensities and high ethylene concentrations, and is adequately accounted for by the reactions[Formula: see text]

scholarly journals Identification and molecular characterization of a Chlamydomonas reinhardtii mutant that shows a light intensity dependent progressive chlorophyll deficiency

F1000Research ◽  
2013 ◽  
Vol 2 ◽  
pp. 142
Author(s):  
Phillip B Grovenstein ◽  
Darryel A Wilson ◽  
Kathryn D Lankford ◽  
Kelsey A Gaston ◽  
Surangi Perera ◽  
...  
Keyword(s):  
Light Intensity ◽  
Insertional Mutagenesis ◽  
Protoporphyrin Ix ◽  
Model Organism ◽  
Genomic Region ◽  
Oxygenic Photosynthesis ◽  
Autotrophic Growth ◽  
Wild Type ◽  
Light Intensities ◽  
In The Wild

The green micro-alga Chlamydomonas reinhardtii is an elegant model organism to study all aspects of oxygenic photosynthesis. Chlorophyll (Chl) and heme are major tetrapyrroles that play an essential role in energy metabolism in photosynthetic organisms. These tetrapyrroles are synthesized via a common branched pathway that involves mainly nuclear encoded enzymes. One of the enzymes in the pathway is Mg chelatase (MgChel) which inserts Mg2+ into protoporphyrin IX (PPIX, proto) to form Magnesium-protoporphyrin IX (MgPPIX, Mgproto), the first biosynthetic intermediate in the Chl branch. The GUN4 (genomes uncoupled 4) protein is not essential for the MgChel activity but has been shown to significantly stimulate its activity. We have isolated a light sensitive mutant, 6F14, by random DNA insertional mutagenesis. 6F14 cannot tolerate light intensities higher than 90-100 μmol photons m-2 s-1. It shows a light intensity dependent progressive photo-bleaching. 6F14 is incapable of photo-autotrophic growth under light intensity higher than 100 μmol photons m-2 s-1. PCR based analyses show that in 6F14 the insertion of the plasmid outside the GUN4 locus has resulted in a genetic rearrangement of the GUN4 gene and possible deletions in the genomic region flanking the GUN4 gene. Our gun4 mutant has a Chl content very similar to that in the wild type in the dark and is very sensitive to fluctuations in the light intensity in the environment unlike the earlier identified Chlamydomonas gun4 mutant. Complementation with a functional copy of the GUN4 gene restored light tolerance, Chl biosynthesis and photo-autotrophic growth under high light intensities in 6F14. 6F14 is the second gun4 mutant to be identified in C. reinhardtii. Additionally, we show that our two gun4 complements over-express the GUN4 protein and show a higher Chl content per cell compared to that in the wild type strain.

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.

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