Bimodal Polarotropism of Vaucheria to Polarized Blue Light: Parallel Polarotropism at High Fluence Rate Corresponds to Negative Phototropism

2000 ◽  
Vol 113 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Hironao Kataoka ◽  
Fumio Takahashi ◽  
Tamotsu Ootaki
Keyword(s):  
Blue Light ◽  
Fluence Rate ◽  
High Fluence ◽  
Negative Phototropism

Perception of shade

1983 ◽  
Vol 303 (1116) ◽  
pp. 503-521 ◽  
Keyword(s):  
Blue Light ◽  
Physiological Responses ◽  
Specific Form ◽  
Radiation Environment ◽  
Physiological Age ◽  
Fluence Rate ◽  
Spectral Quality ◽  
Natural Radiation ◽  
Environment Changes

Plants perceive shade by responding to both the fluence rate and to the spectral quality of the natural radiation environment. Changes in fluence rate are perceived by separate photoreceptors absorbing in both the blue and the red wavebands. The identity of the photoreceptor (or photoreceptors) responding to changes in the fluence rate of blue light is unknown (see Briggs, this volume). Physiological responses to changes in the fluence rate in the red waveband appear to be mediated through phytochrome. The relative roles played by the blue-light-absorbing photoreceptor and phytochrome in determining the response to changes in fluence rate varies between species and organs and is also dependent on the physiological age of the plant. Evidence is also presented that supports the concept that phytochrome functions to perceive the specific form of shade caused by surrounding competitive vegetation.

scholarly journals Phototropism of Conidial Germ Tubes of Botrytis cinerea and Its Implication in Plant Infection Processes

Plant Disease ◽  
1998 ◽  
Vol 82 (8) ◽  
pp. 850-856 ◽  
Author(s):  
S. Z. Islam ◽  
Y. Honda ◽  
M. Sonhaji
Keyword(s):  
Botrytis Cinerea ◽  
Blue Light ◽  
Broad Bean ◽  
Red Light ◽  
Conidial Suspension ◽  
Near Ultraviolet ◽  
Plant Infection ◽  
Negative Phototropism ◽  
Infection Processes ◽  
Germ Tubes

The germ tubes of Botrytis cinerea showed negative phototropism to near ultraviolet (NUV) and blue (300 to 520 nm) light followed by far-red (700 to 810 nm), whereas red light (600 to 700 nm) induced positive phototropism significantly. Minimum germ tube growth occurred during exposure to negative phototropism-inducing wavelengths, whereas it was maximum under positive phototropism-inducing wavelengths. NUV radiation and blue light that induced negative phototropism of B. cinerea promoted infection-hypha formation on both onion scale and broad bean (Vicia faba) leaf epidermal strips, whereas positive phototropism-inducing red light suppressed it, resulting in a high proportion of germ tubes without infection hyphae. In broad bean leaf infection, the number of infection points and area of necrosis per drop of conidial suspension were higher under NUV radiation and blue light than that of a dark control or leaflets pretreated with NUV radiation and blue light. In contrast, lower numbers of infection points and very small necrotic lesions developed under red light. In the case of red-light-pretreated leaflets, the number of infection points developed were higher, but areas of necrosis did not increase significantly compared with leaflets kept under red light without pretreatment. These results show the importance of phototropism of conidium germ tubes in plant infection.

Modulation of reproductive output in Drosophila by spectral properties of ambient light

1986 ◽  
Vol 64 (2) ◽  
pp. 537-542
Author(s):  
Bruce Buhr ◽  
Wayne Wiens ◽  
Marvin Dirks ◽  
Hugh Riordan
Keyword(s):  
Drosophila Melanogaster ◽  
Blue Light ◽  
Spectral Properties ◽  
Reproductive Output ◽  
The Other ◽  
Fluence Rate ◽  
Ambient Light ◽  
Wild Type ◽  
Reproductive Response ◽  
Genetically Determined

The net reproductive output was determined for two strains of Drosophila melanogaster, wild-type (+) and white-eyed (w), under conditions of varied wavelength and intensity of illumination. The reproductive output of wild-type flies raised under blue light (max. 470 nm) was significantly lower (p < 0.01) than that of organisms grown under red (max. 630 and 660 nm) or green(max. 530 nm) illumination, or under conditions of total darkness. In contrast, blue light did not depress the reproductive output of white-eyed flies. The differential reproductive response of the two strains, then, appears to be related to genetically determined properties of the eye. Changes in the radiant fluence rate over a 10-fold range were not found to significantly modify reproductive output of wild-type flies, and if flies were illuminated with red, green, or blue light at identical fluence rates, those under blue, again, had a significantly lower (p < 0.01) reproductive output than the other two. The data suggest that the emission spectrum, not the radiant light intensity, significantly affects the number of offspring produced per parent.

Determination method of high fluence rate for D-T neutron source with long counter

2021 ◽  
pp. 106662
Author(s):  
Yanan Li ◽  
Taosheng Li ◽  
Ying Wang ◽  
Bing Hong ◽  
Feipeng Wang
Keyword(s):  
Neutron Source ◽  
Fluence Rate ◽  
Determination Method ◽  
High Fluence

Influence of light fluence rate on the effects of photodynamic therapy in an orthotopic rat glioma model

2006 ◽  
Vol 104 (1) ◽  
pp. 109-117 ◽  
Author(s):  
Even Angell-Petersen ◽  
Signe Spetalen ◽  
Steen J. Madsen ◽  
Chung-Ho Sun ◽  
Qian Peng ◽  
...  
Keyword(s):  
Photodynamic Therapy ◽  
Aminolevulinic Acid ◽  
Local Treatment ◽  
Local Therapy ◽  
Target Tissue ◽  
Fluence Rate ◽  
High Fluence ◽  
Tumor Induction ◽  
Light Delivery ◽  
Significant Prolongation

Object Failure of treatment for high-grade gliomas is usually due to local recurrence at the site of resection, indicating that a more aggressive local therapy could be beneficial. Photodynamic therapy (PDT) is a local treatment involving the administration of a tumor-localizing photosensitizing drug, in this case aminolevulinic acid (ALA). The effect depends on the total light energy delivered to the target tissue, but may also be influenced by the rate of light delivery. Methods In vitro experiments showed that the sensitivity to ALA PDT of BT4C multicellular tumor spheroids depended on the rate of light delivery (fluence rate). The BT4C tumors were established intracranially in BD-IX rats. Microfluorometry of frozen tissue sections showed that photosensitization is produced with better than 200:1 tumor/normal tissue selectivity after ALA injection. Four hours after intraperitoneal ALA injection (125 mg/kg), 26 J of 632 nm light was delivered interstitially over 15 (high fluence rate) or 90 (low fluence rate) minutes. Histological examination of animals treated 14 days after tumor induction demonstrated extensive tumor necrosis after low-fluence-rate PDT, but hardly any necrosis after high-fluence-rate treatment. Neutrophil infiltration in tumor tissue was increased by PDT, but was similar for both treatment regimens. Low-fluence-rate PDT administered 9 days after tumor induction resulted in statistically significant prolongation of survival for treated rats compared with nontreated control animals. Conclusions Treatment with ALA PDT induced pronounced necrosis in tumors only if the light was delivered at a low rate. The treatment prolonged the survival for tumor-bearing animals.

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