-
Frontiers in Neuroscience 2020The present review draws together wide-ranging studies performed over the last decades that catalogue the effects of artificial-light-at-night (ALAN) upon living species... (Review)
Review
The present review draws together wide-ranging studies performed over the last decades that catalogue the effects of artificial-light-at-night (ALAN) upon living species and their environment. We provide an overview of the tremendous variety of light-detection strategies which have evolved in living organisms - unicellular, plants and animals, covering chloroplasts (plants), and the plethora of ocular and extra-ocular organs (animals). We describe the visual pigments which permit photo-detection, paying attention to their spectral characteristics, which extend from the ultraviolet into infrared. We discuss how organisms use light information in a way crucial for their development, growth and survival: phototropism, phototaxis, photoperiodism, and synchronization of circadian clocks. These aspects are treated in depth, as their perturbation underlies much of the disruptive effects of ALAN. The review goes into detail on circadian networks in living organisms, since these fundamental features are of critical importance in regulating the interface between environment and body. Especially, hormonal synthesis and secretion are often under circadian and circannual control, hence perturbation of the clock will lead to hormonal imbalance. The review addresses how the ubiquitous introduction of light-emitting diode technology may exacerbate, or in some cases reduce, the generalized ever-increasing light pollution. Numerous examples are given of how widespread exposure to ALAN is perturbing many aspects of plant and animal behaviour and survival: foraging, orientation, migration, seasonal reproduction, colonization and more. We examine the potential problems at the level of individual species and populations and extend the debate to the consequences for ecosystems. We stress, through a few examples, the synergistic harmful effects resulting from the impacts of ALAN combined with other anthropogenic pressures, which often impact the neuroendocrine loops in vertebrates. The article concludes by debating how these anthropogenic changes could be mitigated by more reasonable use of available technology - for example by restricting illumination to more essential areas and hours, directing lighting to avoid wasteful radiation and selecting spectral emissions, to reduce impact on circadian clocks. We end by discussing how society should take into account the potentially major consequences that ALAN has on the natural world and the repercussions for ongoing human health and welfare.
PubMed: 33304237
DOI: 10.3389/fnins.2020.602796 -
Frontiers in Bioengineering and... 2022We review fundamental mechanisms and applications of OptoGels: hydrogels with light-programmable properties endowed by photoswitchable proteins ("optoproteins") found in... (Review)
Review
We review fundamental mechanisms and applications of OptoGels: hydrogels with light-programmable properties endowed by photoswitchable proteins ("optoproteins") found in nature. Light, as the primary source of energy on earth, has driven evolution to develop highly-tuned functionalities, such as phototropism and circadian entrainment. These functions are mediated through a growing family of optoproteins that respond to the entire visible spectrum ranging from ultraviolet to infrared by changing their structure to transmit signals inside of cells. In a recent series of articles, engineers and biochemists have incorporated optoproteins into a variety of extracellular systems, endowing them with photocontrollability. While other routes exist for dynamically controlling material properties, light-sensitive proteins have several distinct advantages, including precise spatiotemporal control, reversibility, substrate selectivity, as well as biodegradability and biocompatibility. Available conjugation chemistries endow OptoGels with a combinatorially large design space determined by the set of optoproteins and polymer networks. These combinations result in a variety of tunable material properties. Despite their potential, relatively little of the OptoGel design space has been explored. Here, we aim to summarize innovations in this emerging field and highlight potential future applications of these next generation materials. OptoGels show great promise in applications ranging from mechanobiology, to 3D cell and organoid engineering, and programmable cell eluting materials.
PubMed: 35774061
DOI: 10.3389/fbioe.2022.903982 -
Journal of Experimental Botany Sep 2023This article comments on: Pang L, Kobayashi A, Atsumi Y, Miyazawa Y, Fujii N, Dietrich D, Bennett MJ, Takahashi H. 2023. MIZU-KUSSEI1 (MIZ1) and GNOM/MIZ2 control not...
This article comments on: Pang L, Kobayashi A, Atsumi Y, Miyazawa Y, Fujii N, Dietrich D, Bennett MJ, Takahashi H. 2023. MIZU-KUSSEI1 (MIZ1) and GNOM/MIZ2 control not only positive hydrotropism but also phototropism in Arabidopsis roots. Journal of Experimental Botany 74, 5026–5038.
Topics: Phototropism; Arabidopsis; Tropism
PubMed: 37702013
DOI: 10.1093/jxb/erad293 -
Methods in Molecular Biology (Clifton,... 2019Fern protonemal cells grow at their apices as long, undivided filamentous cells toward red (or weak white) light and change their growth direction if the light direction...
Fern protonemal cells grow at their apices as long, undivided filamentous cells toward red (or weak white) light and change their growth direction if the light direction is changed (i.e., phototropism). When protonemata growing between an agar surface and cover glass are irradiated with polarized red light through the glass on the protonemal side, they start growing at the point where the direction of the vibration plane of polarized light and the transition moment of the photoreceptor, which is parallel to the plasma membrane of the cell's apical part, are equal (i.e., polarotropism). Herein, the methods on how to induce and observe this protonemal phototropism and polarotropism are described.
Topics: Adiantum; Light; Phototropism; Phytochrome
PubMed: 30694464
DOI: 10.1007/978-1-4939-9015-3_3 -
Journal of Experimental Botany Mar 2023Plants recognize the direction of a light source and exhibit phototropic responses. Physiological studies have predicted that differences in the light intensity received... (Review)
Review
Plants recognize the direction of a light source and exhibit phototropic responses. Physiological studies have predicted that differences in the light intensity received by the cells on the irradiated and shaded sides of a coleoptile or hypocotyl cause differences in the amounts of photoproduct. This hypothetical photoproduct appears to regulate a signaling pathway that controls cell elongation in which cells under lower light intensity elongate more than those under higher light intensity. This results in a bending growth toward a light source and has been proposed as the photoproduct-gradient model of phototropism. In this review, we summarize recent findings on the photosensory adaptation mechanisms involving a blue-light photoreceptor, phototropin1 (phot1), ROOT PHOTOTROPISM2, NONPHOTOTROPIC HYPOCOTYL3 (NPH3), and another photoreceptor family, the phytochromes. The current evidence demonstrates that, in addition to the transition of the phot1-NPH3 photoreceptor complexes to their active state, the presence of a certain population of the phot1-NPH3 complexes showing a steady state, even in a light environment, is essential for recognition of the light source direction in phototropism. This is consistent with the photoproduct-gradient model, and a dissociation state of the phot1-NPH3 complex would be considered an entity of the hypothetical photoproduct in this model.
Topics: Phototropism; Arabidopsis; Arabidopsis Proteins; Hypocotyl; Light
PubMed: 36629282
DOI: 10.1093/jxb/erad015 -
Plant Physiology and Biochemistry : PPB Jul 2021Hypocotyl phototropism is redundantly mediated by phot1 and phot2, two blue light receptor phototropins, under the intensity of blue light>1 μmol m s. As light...
Hypocotyl phototropism is redundantly mediated by phot1 and phot2, two blue light receptor phototropins, under the intensity of blue light>1 μmol m s. As light intensity increases, phot1 inhibits the phot2-mediated response. To date, only Arabidopsis Root Phototropism2 (RPT2) has been shown to participate in phot1-mediated inhibition of phototropism. To dissect the signaling network that underlies phot1-mediated inhibition, we carried out a yeast two-hybrid (Y2H) screening assay for RPT2 interacting proteins and identified J-domain protein required for chloroplast accumulation response 1 (JAC1). The interaction between JAC1 and RPT2 was verified by bimolecular fluorescence complementation and Co-IP assays. JAC1 is expressed mainly in cotyledons and hypocotyls. Like RPT2, JAC1 can be induced by blue light, suggesting that it may function similarly to RPT2 in the inhibition of phototropism. Genetic analysis showed that jac1 mutation significantly enhanced the hypocotyl bending of phot1 mutants towards intermediate-intensity blue light, and this effect was inhibited by the constitutive expression of JAC1 in the phot1 jac1 mutant. The phot1 rpt2 double mutant also exhibited enhanced phototropism compared with the phot1 mutant. Taken together, our data clearly demonstrate that JAC1 cooperates with RPT2 to negatively regulate hypocotyl phototropism in plants and may act either downstream of or in parallel with phot1.
Topics: Arabidopsis; Arabidopsis Proteins; Auxilins; Chloroplasts; Hypocotyl; Light; Phosphoproteins; Phototropism
PubMed: 34023643
DOI: 10.1016/j.plaphy.2021.05.007 -
Methods in Molecular Biology (Clifton,... 2019In mosses such as Physcomitrella patens phytochrome photoreceptors steer directional/vectorial responses to unilateral/polarized light. In this chapter, we describe...
In mosses such as Physcomitrella patens phytochrome photoreceptors steer directional/vectorial responses to unilateral/polarized light. In this chapter, we describe procedures to assay phototropism and polarotropism quantitatively in wild type and mutant lines. Protonemata are placed on agar-based medium in square Petri dishes in darkness for 1 week, allowing caulonemata to develop and grow negatively gravitropically. For phototropism, the dishes are placed vertically in black boxes and unilaterally irradiated with continuous red light. For polarotropism, Petri dishes are placed horizontally and irradiated with linearly polarized red light from above. After irradiation, the filaments are photographed using a macroscope with CCD camera and the bending angles measured using image processing software. The data are transfered to a spreadsheet program, placed into 10° bending angle classes and illustrated using a circular histogram.
Topics: Bryopsida; Gravitropism; Light; Phototropism; Phytochrome
PubMed: 31317417
DOI: 10.1007/978-1-4939-9612-4_19 -
Current Opinion in Plant Biology Feb 2019Directional growth in all plants involves both phototropic and gravitropic responses. Accordingly, mechanisms controlling shoot architecture throughout the plant kingdom... (Review)
Review
Directional growth in all plants involves both phototropic and gravitropic responses. Accordingly, mechanisms controlling shoot architecture throughout the plant kingdom are likely similar. However, as forms vary between species due in part to gene copy number and functional divergence, some aspects of how plants predetermine and regulate architecture can differ. This is especially true when comparing annual herbaceous species (e.g. model plants) to woody perennials such as trees. In the past decade, inexpensive genomic sequencing and technological advances enabled gene discovery and functional analyses in trees. This led to the identification of genes associated with tree shoot architecture control. Here, we present recent discoveries on the regulation of shoot architectures for which causative genes have been identified, including dwarf, weeping, columnar, and pillar growth habits. We also discuss potential applications of these findings.
Topics: Genes, Plant; Morphogenesis; Phenotype; Plant Proteins; Plant Shoots; Trees
PubMed: 30339931
DOI: 10.1016/j.pbi.2018.09.010 -
Journal of Plant Research Mar 2016During the course of evolution through various endosymbiotic processes, diverse photosynthetic eukaryotes acquired blue light (BL) responses that do not use... (Review)
Review
During the course of evolution through various endosymbiotic processes, diverse photosynthetic eukaryotes acquired blue light (BL) responses that do not use photosynthetic pathways. Photosynthetic stramenopiles, which have red algae-derived chloroplasts through secondary symbiosis, are principal primary producers in aquatic environments, and play important roles in ecosystems and aquaculture. Through secondary symbiosis, these taxa acquired BL responses, such as phototropism, chloroplast photo-relocation movement, and photomorphogenesis similar to those which green plants acquired through primary symbiosis. Photosynthetic stramenopile BL receptors were undefined until the discovery in 2007, of a new type of BL receptor, the aureochrome (AUREO), from the photosynthetic stramenopile alga, Vaucheria. AUREO has a bZIP domain and a LOV domain, and thus BL-responsive transcription factor. AUREO orthologs are only conserved in photosynthetic stramenopiles, such as brown algae, diatoms, and red tide algae. Here, a brief review is presented of the role of AUREOs as photoreceptors for these diverse BL responses and their biochemical properties in photosynthetic stramenopiles.
Topics: Biological Evolution; Light; Light Signal Transduction; Photoreceptors, Plant; Photosynthesis; Phylogeny; Stramenopiles; Symbiosis; Transcription Factors
PubMed: 26781435
DOI: 10.1007/s10265-016-0784-5 -
Scientific Reports Dec 2016In complex and ever-changing environments, resources such as food are often scarce and unevenly distributed in space and time. Therefore, utilizing external cues to...
In complex and ever-changing environments, resources such as food are often scarce and unevenly distributed in space and time. Therefore, utilizing external cues to locate and remember high-quality sources allows more efficient foraging, thus increasing chances for survival. Associations between environmental cues and food are readily formed because of the tangible benefits they confer. While examples of the key role they play in shaping foraging behaviours are widespread in the animal world, the possibility that plants are also able to acquire learned associations to guide their foraging behaviour has never been demonstrated. Here we show that this type of learning occurs in the garden pea, Pisum sativum. By using a Y-maze task, we show that the position of a neutral cue, predicting the location of a light source, affected the direction of plant growth. This learned behaviour prevailed over innate phototropism. Notably, learning was successful only when it occurred during the subjective day, suggesting that behavioural performance is regulated by metabolic demands. Our results show that associative learning is an essential component of plant behaviour. We conclude that associative learning represents a universal adaptive mechanism shared by both animals and plants.
Topics: Animals; Association Learning; Behavior, Animal; Pisum sativum; Plant Physiological Phenomena
PubMed: 27910933
DOI: 10.1038/srep38427