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Anthony R Cashmore - One of the best experts on this subject based on the ideXlab platform.
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cryptochrome Blue Light photoreceptors of arabidopsis implicated in phototropism
Nature, 1998Co-Authors: Margaret Ahmad, Jose A Jarillo, Olga Smirnova, Anthony R CashmoreAbstract:Phototropism — bending towards the Light — is one of the best known plant tropic responses1,2. Despite being reported by Darwin and others3,4 over a century ago to be specifically under the control of Blue Light, the photoreceptors mediating phototropism have remained unknown. We have characterized a Blue-Light photoreceptor from Arabidopsis, named CRY1 for cryptochrome 1 (ref. 5); this photoreceptor is a flavoprotein that mediates numerous Blue-Light-dependent responses6. In Arabidopsis, HY4 (the gene encoding CRY1) is a member of a small gene family that also encodes a related photoreceptor, CRY2 (refs 7, 8), which shares considerable functional overlap with CRY1 (ref. 9). Here we report that mutant plants lacking both the CRY1 and the CRY2 Blue-Light photoreceptors are deficient in the phototropic response. Transgenic Arabidopsis plants overexpressing CRY1 or CRY2 show enhanced phototropic curvature. We conclude that cryptochrome is one of the photoreceptors mediating phototropism in plants.
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enhancement of Blue Light sensitivity of arabidopsis seedlings by a Blue Light receptor cryptochrome 2
Proceedings of the National Academy of Sciences of the United States of America, 1998Co-Authors: Hongyun Yang, Todd C. Mockler, Jeff Chen, Anthony R CashmoreAbstract:Cryptochrome is a group of flavin-type Blue Light receptors that regulate plant growth and development. The function of Arabidopsis cryptochrome 2 in the early photomorphogenesis of seedlings was studied by using transgenic plants overexpressing CRY2 protein, and cry2 mutant plants accumulating no CRY2 protein. It is found that cryptochrome 2 mediates Blue Light-dependent inhibition of hypocotyl elongation and stimulation of cotyledon opening under low intensities of Blue Light. In contrast to CRY1, the expression of CRY2 is rapidly down-regulated by Blue Light in a Light-intensity dependent manner, which provides a molecular mechanism to explain at least in part that cryptochrome 2 functions primarily under low Light during the early development of seedlings.
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hy4 gene of a thaliana encodes a protein with characteristics of a Blue Light photoreceptor
Nature, 1993Co-Authors: Margaret Ahmad, Anthony R CashmoreAbstract:Specific responses to Blue Light are found throughout the biological kingdom. These responses--which in higher plants include phototropism, inhibition of hypocotyl elongation, and stomatal opening--are in many cases thought to be mediated by flavin-type photoreceptors. But no such Blue-Light photoreceptor has yet been identified or isolated, although Blue-Light responses in plants were reported by Darwin over a century ago, long before the discovery of the now relatively well characterized red/far-red Light photoreceptor, phytochrome. Here we describe the isolation of a gene corresponding to the HY4 locus of Arabidopsis thaliana. The hy4 mutant is one of several mutants that are selectively insensitive to Blue Light during the Blue-Light-dependent inhibition of hypocotyl elongation response, which suggests that they lack an essential component of the cryptochrome-associated Light-sensing pathway. The HY4 gene, isolated by gene tagging, was shown to encode a protein with significant homology to microbial DNA photolyases. As photolyases are a rare class of flavoprotein that catalyse Blue-Light-dependent reactions, the protein encoded by HY4 has a structure consistent with that of a flavin-type Blue-Light photoreceptor.
Hongyun Yang - One of the best experts on this subject based on the ideXlab platform.
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Regulation of Arabidopsis cryptochrome 2 by Blue-Light-dependent phosphorylation.
Nature, 2002Co-Authors: Dror Shalitin, Maskit Maymon, Hongyun Yang, Todd C. Mockler, Garry C. WhitelamAbstract:Cryptochromes are Blue/ultraviolet-A Light receptors that mediate various Light responses in plants and animals1,2. But the initial photochemical reaction of cryptochrome is still unclear. For example, although most photoreceptors are known to undergo Light-dependent protein modification such as phosphorylation3,4, no Blue-Light dependent phosphorylation has been reported for a cryptochrome. Arabidopsis cryptochrome 2 (cry2) mediates Light regulation of seedling development and photoperiodic flowering5,6. The physiological activity and cellular level of cry2 protein are Light-dependent5,6,7,8, and protein–protein interactions are important for cry2 function9,10. Here we report that cry2 undergoes a Blue-Light-dependent phosphorylation, and that cry2 phosphorylation is associated with its function and regulation. Our results suggest that, in the absence of Light, cry2 remains unphosphorylated, inactive and stable; absorption of Blue Light induces the phosphorylation of cry2, triggering photomorphogenic responses and eventually degradation of the photoreceptor.
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enhancement of Blue Light sensitivity of arabidopsis seedlings by a Blue Light receptor cryptochrome 2
Proceedings of the National Academy of Sciences of the United States of America, 1998Co-Authors: Hongyun Yang, Todd C. Mockler, Jeff Chen, Anthony R CashmoreAbstract:Cryptochrome is a group of flavin-type Blue Light receptors that regulate plant growth and development. The function of Arabidopsis cryptochrome 2 in the early photomorphogenesis of seedlings was studied by using transgenic plants overexpressing CRY2 protein, and cry2 mutant plants accumulating no CRY2 protein. It is found that cryptochrome 2 mediates Blue Light-dependent inhibition of hypocotyl elongation and stimulation of cotyledon opening under low intensities of Blue Light. In contrast to CRY1, the expression of CRY2 is rapidly down-regulated by Blue Light in a Light-intensity dependent manner, which provides a molecular mechanism to explain at least in part that cryptochrome 2 functions primarily under low Light during the early development of seedlings.
Todd C. Mockler - One of the best experts on this subject based on the ideXlab platform.
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Regulation of Arabidopsis cryptochrome 2 by Blue-Light-dependent phosphorylation.
Nature, 2002Co-Authors: Dror Shalitin, Maskit Maymon, Hongyun Yang, Todd C. Mockler, Garry C. WhitelamAbstract:Cryptochromes are Blue/ultraviolet-A Light receptors that mediate various Light responses in plants and animals1,2. But the initial photochemical reaction of cryptochrome is still unclear. For example, although most photoreceptors are known to undergo Light-dependent protein modification such as phosphorylation3,4, no Blue-Light dependent phosphorylation has been reported for a cryptochrome. Arabidopsis cryptochrome 2 (cry2) mediates Light regulation of seedling development and photoperiodic flowering5,6. The physiological activity and cellular level of cry2 protein are Light-dependent5,6,7,8, and protein–protein interactions are important for cry2 function9,10. Here we report that cry2 undergoes a Blue-Light-dependent phosphorylation, and that cry2 phosphorylation is associated with its function and regulation. Our results suggest that, in the absence of Light, cry2 remains unphosphorylated, inactive and stable; absorption of Blue Light induces the phosphorylation of cry2, triggering photomorphogenic responses and eventually degradation of the photoreceptor.
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enhancement of Blue Light sensitivity of arabidopsis seedlings by a Blue Light receptor cryptochrome 2
Proceedings of the National Academy of Sciences of the United States of America, 1998Co-Authors: Hongyun Yang, Todd C. Mockler, Jeff Chen, Anthony R CashmoreAbstract:Cryptochrome is a group of flavin-type Blue Light receptors that regulate plant growth and development. The function of Arabidopsis cryptochrome 2 in the early photomorphogenesis of seedlings was studied by using transgenic plants overexpressing CRY2 protein, and cry2 mutant plants accumulating no CRY2 protein. It is found that cryptochrome 2 mediates Blue Light-dependent inhibition of hypocotyl elongation and stimulation of cotyledon opening under low intensities of Blue Light. In contrast to CRY1, the expression of CRY2 is rapidly down-regulated by Blue Light in a Light-intensity dependent manner, which provides a molecular mechanism to explain at least in part that cryptochrome 2 functions primarily under low Light during the early development of seedlings.
Ken-ichiro Shimazaki - One of the best experts on this subject based on the ideXlab platform.
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Blue Light induced rapid chloroplast de anchoring in vallisneria epidermal cells
Journal of Integrative Plant Biology, 2015Co-Authors: Yuuki Sakai, Ken-ichiro Shimazaki, Akiko Harada, Shinichiro Inoue, Shingo TakagiAbstract:In the outer periclinal cytoplasm of leaf epidermal cells of an aquatic angiosperm Vallisneria, Blue Light induces “chloroplast de-anchoring”, a rapid decline in the resistance of chloroplasts against centrifugal force. Chloroplast de-anchoring is known induced within 1 min of irradiation with high-fluence-rate Blue Light specifically, preceding the commencement of chloroplasts migration toward the anticlinal cytoplasm. However, its regulatory mechanism has remained elusive, although pharmacological analysis suggested that a calcium release from intracellular calcium stores is necessary for the response. In search of the responsible photoreceptors, immunoblotting analysis using antibodies against phototropins demonstrated that cross-reactive polypeptides of 120-kDa exist in the plasma-membrane fraction prepared from the leaves. In vitro phosphorylation analysis revealed that 120-kDa polypeptides were phosphorylated by exposure to Blue Light in a fluence-dependent manner. The Blue-Light-induced phosphorylation activity was sensitive to a Ser/Thr kinase inhibitor, staurosporine, and unusually was retained at a high level for a long time in darkness. Furthermore, phototropin gene homologs (Vallisneria PHOTOTROPIN1 and PHOTOTROPIN2) expressed in leaves were isolated. We propose that calcium-regulated chloroplast de-anchoring, possibly mediated by phototropins, is an initial process of the Blue-Light-induced avoidance response of chloroplasts in Vallisneria.
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protein phosphatase 1 positively regulates stomatal opening in response to Blue Light in vicia faba
Proceedings of the National Academy of Sciences of the United States of America, 2006Co-Authors: Atsushi Takemiya, Toshinori Kinoshita, Miwako Asanuma, Ken-ichiro ShimazakiAbstract:Phototropins, plant Blue Light receptors, mediate stomatal opening through the activation of the plasma membrane H+-ATPase by unknown mechanisms. Here we report that type 1 protein phosphatase (PP1) positively regulates the Blue Light signaling between phototropins and the H+-ATPase in guard cells of Vicia faba. We cloned the four catalytic subunits of PP1 (PP1c) from guard cells and determined the expression of the isoforms in various tissues. Transformation of Vicia guard cells with PP1c isoforms that had lost enzymatic activity by one amino acid mutation, or with human inhibitor-2, a specific inhibitor protein of PP1c, suppressed Blue Light-induced stomatal opening. Addition of fusicoccin, an activator of the plasma membrane H+-ATPase, to these transformed guard cells induced normal stomatal opening, suggesting that the transformations did not affect the basic mechanisms for stomatal opening. Tautomycin, an inhibitor of PP1, inhibited Blue Light-induced H+ pumping, phosphorylation of the plasma membrane H+-ATPase in guard cell protoplasts, and stomatal opening. However, tautomycin did not inhibit the Blue Light-dependent phosphorylation of phototropins. We conclude that PP1 functions downstream of phototropins and upstream of the H+-ATPase in the Blue Light signaling pathway of guard cells.
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The Fern Adiantum capillus-veneris Lacks Stomatal Responses to Blue Light
Plant and Cell Physiology, 2006Co-Authors: Michio Doi, Masamitsu Wada, Ken-ichiro ShimazakiAbstract:;We investigated the responses of stomata to Light in the fern Adiantum capillus-veneris, a typical species of Leptosporangiopsida. Stomata in the intact leaves of the sporophytes opened in response to red Light, but they did not open when Blue Light was superimposed on the red Light. The results were confirmed in the isolated Adiantum epidermis. The red Light-induced stomatal response was not affected by the mutation of phy3, a chimeric protein of phytochrome and phototropin in this fern. The lack of a Blue Light-specific stomatal response was observed in three other fern species of Leptosporangiopsida, i.e. Pteris cretica, Asplenium scolopendrium and Nephrolepis auriculata. Fusicoccin, an activator of the plasma membrane H + -ATPase, induced both stomatal opening and H + release in the Adiantum epidermis. Adiantum phototropin genes AcPHOT1 and AcPHOT2 were expressed in the fern guard cells. The transformation of an Arabidopsis phot1 phot2 double mutant, which lost Blue Light-specific stomatal opening, with AcPHOT1 restored the stomatal response to Blue Light. Taken together, these results suggest that ferns of Leptosporangiopsida lack a Blue Light-specific stomatal response, although the functional phototropin and plasma membrane H + -ATPase are present in this species.
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phot1 and phot2 mediate Blue Light regulation of stomatal opening
Nature, 2001Co-Authors: Toshinori Kinoshita, Masamitsu Wada, Michio Doi, Noriyuki Suetsugu, Takatoshi Kagawa, Ken-ichiro ShimazakiAbstract:The stomatal pores of higher plants allow for gaseous exchange into and out of leaves. Situated in the epidermis, they are surrounded by a pair of guard cells which control their opening in response to many environmental stimuli, including Blue Light. Opening of the pores is mediated by K(+) accumulation in guard cells through a K(+) channel and driven by an inside-negative electrical potential. Blue Light causes phosphorylation and activation of the plasma membrane H(+)-ATPase that creates this potential. Thus far, no Blue Light receptor mediating stomatal opening has been identified, although the carotenoid, zeaxanthin, has been proposed. Arabidopsis mutants deficient in specific Blue-Light-mediated responses have identified four Blue Light receptors, cryptochrome 1 (cry1), cryptochrome 2 (cry2), phot1 and phot2. Here we show that in a double mutant of phot1 and phot2 stomata do not respond to Blue Light although single mutants are phenotypically normal. These results demonstrate that phot1 and phot2 act redundantly as Blue Light receptors mediating stomatal opening.
Michael R Hamblin - One of the best experts on this subject based on the ideXlab platform.
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antimicrobial Blue Light inactivation of pathogenic microbes state of the art
Drug Resistance Updates, 2017Co-Authors: Yuguang Wang, Michael R Hamblin, Ying Wang, Yucheng Wang, David C HooperAbstract:Abstract As an innovative non-antibiotic approach, antimicrobial Blue Light in the spectrum of 400–470 nm has demonstrated its intrinsic antimicrobial properties resulting from the presence of endogenous photosensitizing chromophores in pathogenic microbes and, subsequently, its promise as a counteracter of antibiotic resistance. Since we published our last review of antimicrobial Blue Light in 2012, there have been a substantial number of new studies reported in this area. Here we provide an updated overview of the findings from the new studies over the past 5 years, including the efficacy of antimicrobial Blue Light inactivation of different microbes, its mechanism of action, synergism of antimicrobial Blue Light with other angents, its effect on host cells and tissues, the potential development of resistance to antimicrobial Blue Light by microbes, and a novel interstitial delivery approach of antimicrobial Blue Light. The potential new applications of antimicrobial Blue Light are also discussed.
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antimicrobial Blue Light therapy for candida albicans burn infection in mice
Proceedings of SPIE, 2015Co-Authors: Michael R Hamblin, Yucheng Wang, Clinton K. Murray, Yunsong Zhang, Tianhong DaiAbstract:In this preclinical study, we investigated the utility of antimicrobial Blue Light therapy for Candida albicans infection in acutely burned mice. A bioluminescent strain of C. albicans was used. The susceptibilities to Blue Light inactivation were compared between C. albicans and human keratinocyte. In vitro serial passaging of C. albicans on Blue Light exposure was performed to evaluate the potential development of resistance to Blue Light inactivation. A mouse model of acute thermal burn injury infected with the bioluminescent strain of C. albicans was developed. Blue Light (415 nm) was delivered to mouse burns for decolonization of C. albicans. Bioluminescence imaging was used to monitor in real time the extent of fungal infection in mouse burns. Experimental results showed that C. albicans was approximately 42-fold more susceptible to Blue Light inactivation in vitro than human keratinocyte (P=0.0022). Serial passaging of C. albicans on Blue Light exposure implied a tendency for the fungal susceptibility to Blue Light inactivation to decrease with the numbers of passages. Blue Light reduced fungal burden by over 4-log10 (99.99%) in acute mouse burns infected with C. albicans in comparison to infected mouse burns without Blue Light therapy (P=0.015).
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Blue Light for infectious diseases propionibacterium acnes helicobacter pylori and beyond
Drug Resistance Updates, 2012Co-Authors: Tianhong Dai, Michael R Hamblin, Asheesh Gupta, Clinton K. Murray, Mark S. Vrahas, George P. TegosAbstract:Blue Light, particularly in the wavelength range of 405-470 nm, has attracted increasing attention due to its intrinsic antimicrobial effect without the addition of exogenous photosensitizers. In addition, it is commonly accepted that Blue Light is much less detrimental to mammalian cells than ultraviolet irradiation, which is another Light-based antimicrobial approach being investigated. In this review, we discussed the Blue Light sensing systems in microbial cells, antimicrobial efficacy of Blue Light, the mechanism of antimicrobial effect of Blue Light, the effects of Blue Light on mammalian cells, and the effects of Blue Light on wound healing. It has been reported that Blue Light can regulate multi-cellular behavior involving cell-to-cell communication via Blue Light receptors in bacteria, and inhibit biofilm formation and subsequently potentiate Light inactivation. At higher radiant exposures, Blue Light exhibits a broad-spectrum antimicrobial effect against both Gram-positive and Gram-negative bacteria. Blue Light therapy is a clinically accepted approach for Propionibacterium acnes infections. Clinical trials have also been conducted to investigate the use of Blue Light for Helicobacter pylori stomach infections and have shown promising results. Studies on Blue Light inactivation of important wound pathogenic bacteria, including Staphylococcus aureus and Pseudomonas aeruginosa have also been reported. The mechanism of Blue Light inactivation of P. acnes, H. pylori, and some oral bacteria is proved to be the photo-excitation of intracellular porphyrins and the subsequent production of cytotoxic reactive oxygen species. Although it may be the case that the mechanism of Blue Light inactivation of wound pathogens (e.g., S. aureus, P. aeruginosa) is the same as that of P. acnes, this hypothesis has not been rigorously tested. Limited and discordant results have been reported regarding the effects of Blue Light on mammalian cells and wound healing. Under certain wavelengths and radiant exposures, Blue Light may cause cell dysfunction by the photo-excitation of Blue Light sensitizing chromophores, including flavins and cytochromes, within mitochondria or/and peroxisomes. Further studies should be performed to optimize the optical parameters (e.g., wavelength, radiant exposure) to ensure effective and safe Blue Light therapies for infectious disease. In addition, studies are also needed to verify the lack of development of microbial resistance to Blue Light.