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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 -
PLoS Biology Oct 2023Sunflowers are famous for their ability to track the sun throughout the day and then reorient at night to face east the following morning. This occurs by differential...
Sunflowers are famous for their ability to track the sun throughout the day and then reorient at night to face east the following morning. This occurs by differential growth patterns, with the east sides of stems growing more during the day and the west sides of stems growing more at night. This process, termed heliotropism, is generally believed to be a specialized form of phototropism; however, the underlying mechanism is unknown. To better understand heliotropism, we compared gene expression patterns in plants undergoing phototropism in a controlled environment and in plants initiating and maintaining heliotropic growth in the field. We found the expected transcriptome signatures of phototropin-mediated phototropism in sunflower stems bending towards monochromatic blue light. Surprisingly, the expression patterns of these phototropism-regulated genes are quite different in heliotropic plants. Most genes rapidly induced during phototropism display only minor differences in expression across solar tracking stems. However, some genes that are both rapidly induced during phototropism and are implicated in growth responses to foliar shade are rapidly induced on the west sides of stems at the onset of heliotropism, suggesting a possible role for red light photoreceptors in solar tracking. To test the involvement of different photoreceptor signaling pathways in heliotropism, we modulated the light environment of plants initiating solar tracking. We found that depletion of either red and far-red light or blue light did not hinder the initiation or maintenance of heliotropism in the field. Together, our results suggest that the transcriptional regulation of heliotropism is distinct from phototropin-mediated phototropism and likely involves inputs from multiple light signaling pathways.
Topics: Helianthus; Phototropins; Sunlight; Light; Phototropism; Signal Transduction; Arabidopsis Proteins
PubMed: 37906610
DOI: 10.1371/journal.pbio.3002344 -
Communications Biology Jan 2024Plant organs shift their directional growth in response to environmental stimuli through tropisms. Arabidopsis roots exhibit positive hydrotropism (towards water) and...
Plant organs shift their directional growth in response to environmental stimuli through tropisms. Arabidopsis roots exhibit positive hydrotropism (towards water) and negative phototropism (away from light). In a recent study, Pang and colleagues demonstrated that root phototropism is regulated by the activity of two proteins in the elongation zone that also play essential roles in hydrotropism.
PubMed: 38195918
DOI: 10.1038/s42003-023-05707-z -
Quantitative Plant Biology 2023An increasing number of collaborative projects between artists and scientists raises the question regarding their value, particularly when considering the redirection of...
An increasing number of collaborative projects between artists and scientists raises the question regarding their value, particularly when considering the redirection of resources. Here we provide a personal account of our collaborative efforts, as an artist and a scientist. We propose that one of the most significant outcomes is something that cannot be planned for in advance: serendipitous events. Such events lead to fresh perspectives and imaginative ideas, the fairy dust underlying many great works of art and science. The unexpected nature of these desired outcomes requires from us a leap of faith on the one hand, and a deep trust in our 'partner in crime' on the other.
PubMed: 37587987
DOI: 10.1017/qpb.2023.7 -
Stress Biology Jul 2023Phototropism is a classic adaptive growth response that helps plants to enhance light capture for photosynthesis. It was shown that hydrogen peroxide (HO) participates...
Phototropism is a classic adaptive growth response that helps plants to enhance light capture for photosynthesis. It was shown that hydrogen peroxide (HO) participates in the regulation of blue light-induced hypocotyl phototropism; however, the underlying mechanism is unclear. In this study, we demonstrate that the unilateral high-intensity blue light (HBL) could induce asymmetric distribution of HO in cotton hypocotyls. Disruption of the HBL-induced asymmetric distribution of HO by applying either HO itself evenly on the hypocotyls or HO scavengers on the lit side of hypocotyls could efficiently inhibit hypocotyl phototropic growth. Consistently, application of HO on the shaded and lit sides of the hypocotyls led to reduced and enhanced hypocotyl phototropism, respectively. Further, we show that HO inhibits hypocotyl elongation of cotton seedlings, thus supporting the repressive role of HO in HBL-induced hypocotyl phototropism. Moreover, our results show that HO interferes with HBL-induced asymmetric distribution of auxin in the cotton hypocotyls. Taken together, our study uncovers that HO changes the asymmetric accumulation of auxin and inhibits hypocotyl cell elongation, thus mediating HBL-induced hypocotyl phototropism.
PubMed: 37676397
DOI: 10.1007/s44154-023-00111-3 -
Biomolecules Mar 2024A Type I reaction center (RC) (Fe-S type, ferredoxin reducing) is found in several phyla containing anoxygenic phototrophic bacteria. These include the heliobacteria... (Review)
Review
A Type I reaction center (RC) (Fe-S type, ferredoxin reducing) is found in several phyla containing anoxygenic phototrophic bacteria. These include the heliobacteria (HB), the green sulfur bacteria (GSB), and the chloracidobacteria (CB), for which high-resolution homodimeric RC-photosystem (PS) structures have recently appeared. The 2.2-Å X-ray structure of the RC-PS of revealed that the core PshA apoprotein (PshA-1 and PshA-2 homodimeric pair) exhibits a structurally conserved PSI arrangement comprising five C-terminal transmembrane α-helices (TMHs) forming the RC domain and six N-terminal TMHs coordinating the light-harvesting (LH) pigments. The structure lacked quinone molecules, indicating that electrons were transferred directly from the A (8-OH-chlorophyll (Chl) ) acceptor to the F [4Fe-4S] component, serving as the terminal RC acceptor. A pair of additional TMHs designated as Psh X were also found that function as a low-energy antenna. The 2.5-Å resolution cryo-electron microscopy (cryo-EM) structure for the RC-PS of the green sulfur bacterium included a pair of Fenna-Matthews-Olson protein (FMO) antennae, which transfer excitations from the chlorosomes to the RC-PS (PscA-1 and PscA-2) core. A pair of cytochromes (PscC) molecules was also revealed, acting as electron donors to the RC bacteriochlorophyll (BChl) ' special pair, as well as PscB, housing the [4Fe-4S] cluster F and F, and the associated PscD protein. While the FMO components were missing from the 2.6-Å cryo-EM structure of the Zn- (BChl) ' special pair containing RC-PS of , a unique architecture was revealed that besides the (PscA) core, consisted of seven additional subunits including PscZ in place of PscD, the PscX and PscY cytochrome serial electron donors and four low mol. wt. subunits of unknown function. Overall, these diverse structures have revealed that (i) the HB RC-PS is the simplest light-energy transducing complex yet isolated and represents the closest known homolog to a common homodimeric RC-PS ancestor; (ii) the symmetrically localized Ca-binding sites found in each of the Type I homodimeric RC-PS structures likely gave rise to the analogously positioned MnCaO cluster of the PSII RC and the Tyr RC donor site; (iii) a close relationship between the GSB RC-PS and the PSII Chl proteins (CP)43 and CP47 was demonstrated by their strongly conserved LH-(B)Chl localizations; (iv) LH-BChls of the GSB-RC-PS are also localized in the conserved RC-associated positions of the PSII Chl and Chl sites; (v) glycosylated carotenoids of the GSB RC-PS are located in the homologous carotenoid-containing positions of PSII, reflecting an O-tolerance mechanism capable of sustaining early stages in the evolution of oxygenic photosynthesis. In addition to the close relationships found between the homodimeric RC-PS and PSII, duplication of the gene encoding the ancestral Type I RC apoprotein, followed by genetic divergence, may well account for the appearance of the heterodimeric Type I and Type II RCs of the extant oxygenic phototrophs. Accordingly, the long-held view that PSII arose from the anoxygenic Type II RC is now found to be contrary to the new evidence provided by Type I RC-PS homodimer structures, indicating that the evolutionary origins of anoxygenic Type II RCs, along with their distinct antenna rings are likely to have been preceded by the events that gave rise to their oxygenic counterparts.
Topics: Chlorobi; Photosynthetic Reaction Center Complex Proteins; Cryoelectron Microscopy; Bacteria; Apoproteins; Bacterial Proteins
PubMed: 38540731
DOI: 10.3390/biom14030311 -
Plants (Basel, Switzerland) Jan 2024Gravitropism is the plant organ bending in response to gravity. Gravitropism, phototropism and sufficient mechanical strength define the optimal position of young shoots...
Gravitropism is the plant organ bending in response to gravity. Gravitropism, phototropism and sufficient mechanical strength define the optimal position of young shoots for photosynthesis. Etiolated wild-type Arabidopsis seedlings grown horizontally in the presence of sucrose had a lot more upright hypocotyls than seedlings grown without sucrose. We studied the mechanism of this effect at the level of cell wall biomechanics and biochemistry. Sucrose strengthened the bases of hypocotyls and decreased the content of mannans in their cell walls. As sucrose is known to increase the gravitropic bending of hypocotyls, and mannans have recently been shown to interfere with this process, we examined if the effect of sucrose on shoot gravitropism could be partially mediated by mannans. We compared cell wall biomechanics and metabolomics of hypocotyls at the early steps of gravitropic bending in Col-0 plants grown with sucrose and mannan-deficient mutant seedlings. Sucrose and mannans affected gravitropic bending via different mechanisms. Sucrose exerted its effect through cell wall-loosening proteins, while mannans changed the walls' viscoelasticity. Our data highlight the complexity of shoot gravitropism control at the cell wall level.
PubMed: 38256762
DOI: 10.3390/plants13020209 -
BioRxiv : the Preprint Server For... Feb 2024Optimal imaging strategies remain underdeveloped to maximize information for fluorescence microscopy while minimizing the harm to fragile living systems. Taking hint...
Optimal imaging strategies remain underdeveloped to maximize information for fluorescence microscopy while minimizing the harm to fragile living systems. Taking hint from the supercontinuum generation in ultrafast laser physics, we generated supercontinuum fluorescence from untreated unlabeled live samples before nonlinear photodamage onset. Our imaging achieved high-content cell phenotyping and tissue histology, identified bovine embryo polarization, quantified aging-related stress across cell types and species, demystified embryogenesis before and after implantation, sensed drug cytotoxicity in real-time, scanned brain area for targeted patching, optimized machine learning to track small moving organisms, induced two-photon phototropism of leaf chloroplasts under two-photon photosynthesis, unraveled microscopic origin of autumn colors, and interrogated intestinal microbiome. The results enable a facility-type microscope to freely explore vital molecular biology across life sciences.
PubMed: 38328159
DOI: 10.1101/2024.01.26.577383 -
The Plant Cell Jun 2023PHYTOCHROME KINASE SUBSTRATE (PKS) proteins are involved in light-modulated changes in growth orientation. They act downstream of phytochromes to control hypocotyl...
PHYTOCHROME KINASE SUBSTRATE (PKS) proteins are involved in light-modulated changes in growth orientation. They act downstream of phytochromes to control hypocotyl gravitropism in the light and act early in phototropin signaling. Despite their importance for plant development, little is known about their molecular mode of action, except that they belong to a protein complex comprising phototropins at the plasma membrane (PM). Identifying evolutionary conservation is one approach to revealing biologically important protein motifs. Here, we show that PKS sequences are restricted to seed plants and that these proteins share 6 motifs (A to F from the N to the C terminus). Motifs A and D are also present in BIG GRAIN, while the remaining 4 are specific to PKSs. We provide evidence that motif C is S-acylated on highly conserved cysteines, which mediates the association of PKS proteins with the PM. Motif C is also required for PKS4-mediated phototropism and light-regulated hypocotyl gravitropism. Finally, our data suggest that the mode of PKS4 association with the PM is important for its biological activity. Our work, therefore, identifies conserved cysteines contributing to PM association of PKS proteins and strongly suggests that this is their site of action to modulate environmentally regulated organ positioning.
Topics: Phytochrome; Arabidopsis Proteins; Arabidopsis; Protein S; Light; Phototropism; Hypocotyl; Acylation
PubMed: 36972404
DOI: 10.1093/plcell/koad096 -
Journal of Nanobiotechnology May 2024Elevated interstitial fluid pressure within tumors, resulting from impaired lymphatic drainage, constitutes a critical barrier to effective drug penetration and...
BACKGROUND
Elevated interstitial fluid pressure within tumors, resulting from impaired lymphatic drainage, constitutes a critical barrier to effective drug penetration and therapeutic outcomes.
RESULTS
In this study, based on the photosynthetic characteristics of algae, an active drug carrier (CP@ICG) derived from Chlorella pyrenoidosa (CP) was designed and constructed. Leveraging the hypoxia tropism and phototropism exhibited by CP, we achieved targeted transport of the carrier to tumor sites. Additionally, dual near-infrared (NIR) irradiation at the tumor site facilitated photosynthesis in CP, enabling the breakdown of excessive intratumoral interstitial fluid by generating oxygen from water decomposition. This process effectively reduced the interstitial pressure, thereby promoting enhanced perfusion of blood into the tumor, significantly improving deep-seated penetration of chemotherapeutic agents, and alleviating tumor hypoxia.
CONCLUSIONS
CP@ICG demonstrated a combined effect of photothermal/photodynamic/starvation therapy, exhibiting excellent in vitro/in vivo anti-tumor efficacy and favorable biocompatibility. This work provides a scientific foundation for the application of microbial-enhanced intratumoral drug delivery and tumor therapy.
Topics: Animals; Photosynthesis; Mice; Cell Line, Tumor; Chlorella; Drug Carriers; Humans; Combined Modality Therapy; Photochemotherapy; Neoplasms; Antineoplastic Agents; Mice, Inbred BALB C; Drug Delivery Systems; Indocyanine Green; Female
PubMed: 38711078
DOI: 10.1186/s12951-024-02476-7