Impact of Rainfall on the Detection Performance of Non-Contact Safety Sensors for UAVs/UGVs.

This study comprehensively investigates how rain and drizzle affect the object-detection performance of non-contact safety sensors, which are essential for the operation of unmanned aerial vehicles and ground vehicles in adverse weather conditions. In contrast to conventional sensor-performance evaluation based on the amount of precipitation, this paper proposes spatial transmittance and particle density as more appropriate metrics for rain environments. Through detailed experiments conducted under a variety of precipitation conditions, it is shown that sensor performance is significantly affected by the density of small raindrops rather than the total amount of precipitation. This finding challenges traditional sensor-evaluation metrics in rainfall environments and suggests a paradigm shift toward the use of spatial transmittance as a universal metric for evaluating sensor performance in rain, drizzle, and potentially other adverse weather scenarios.

Mechanism of action and selectivity of a novel herbicide, fenquinotrione.

Fenquinotrione is a novel herbicide that can control a wide range of broadleaf and sedge weeds with excellent rice selectivity. We revealed that fenquinotrione potently inhibited the 4-hydroxyphenylpyruvate dioxygenase (HPPD) activity in Arabidopsis thaliana with an IC50 of 44.7 nM. The docking study suggested that the 1,3-diketone moiety of fenquinotrione formed a bidentate interaction with Fe(II) at the active site. Furthermore, π-π stacking interactions occurred between the oxoquinoxaline ring and the conserved Phe409 and Phe452 rings, indicating that fenquinotrione competes with the substrate, similar to existing HPPD inhibitors. A more than 16-fold difference in the herbicidal activity of fenquinotrione in rice and the sedge, Schoenoplectus juncoides, was observed. However, fenquinotrione showed high inhibitory activity against rice HPPD. Comparative metabolism study suggested that the potent demethylating metabolism followed by glucose conjugation in rice was responsible for the selectivity of fenquinotrione.

Light-Induced Electron Spin-Polarized (ESP) EPR Signal of the P800+ Menaquinone- Radical Pair State in Oriented Membranes of Heliobacterium modesticaldum: Role/Location of Menaquinone in the Homodimeric Type I Reaction Center.

Function/location of menaquinone (MQ) was studied in the photosynthetic reaction center of Heliobacterium (Hbt.) modesticaldum (hRC), which is one of the most primitive homodimeric type I RCs. The spin-polarized electron paramagnetic resonance signals of light-induced radical pair species, which are made of oxidized electron donor bacteriochlorophyll g (P800+) and reduced menaquinone (MQ-) or iron-sulfur cluster (FX-), were measured in the oriented membranes of Hbt. modesticaldum at cryogenic temperature. The spectral shape of transient electron spin-polarized signal of P800+FX- radical pair state varied little with respect to the direction of the external magnetic field. It suggested a dominant contribution of the spin evolution on the precursor primary radical pair P800+A0- state with the larger isotropic magnetic exchange interaction J than the anisotropic dipole interaction D. The pure P800+MQ- signal was simulated by subtracting the effects of spin evolution during the electron-transfer process. It was concluded that the J value of the P800+MQ- radical pair is negative with an amplitude almost comparable to | D|. It is in contrast to a positive and small J value of the P700+PhyQ- state in photosystem I (PS I). The results indicate similar but somewhat different locations/binding sites of quinones between hRC and PS I.

[Breast Cancer Patient with Bone Metastases Who Was Able to Return Home without Using Opioids after Administration of Strontium-89 Chloride].

A 46-year-old woman underwent mastectomy for right inflammatory breast cancer.Three years later, she was diagnosed with multiple bone metastases and was treated with systemic chemotherapy and zoledronic acid.Six years after the mastectomy, she complained of severe sacral pain, and 40 Gy external radiotherapy was applied to the sacral metastases.Oxycodone was also administered, but dose escalation was difficult because of severe nausea and fatigue.A bone scan showed increased uptake of Tc99m in an area consistent with the painful regions, and an injection of 89SrCl2 was administered.Five weeks after the injection, her severe pain was relieved and she was able to discontinue the use of opioids completely.She successfully lived at home for 100 days without using opioids.In this case, radionuclide therapy with 89SrCl2 led to remarkable pain relief with an improvement in the quality of life of the patient.

Unique chlorophylls in picoplankton Prochlorococcus sp. "Physicochemical properties of divinyl chlorophylls, and the discovery of monovinyl chlorophyll b as well as divinyl chlorophyll b in the species Prochlorococcus NIES-2086".

In this review, we introduce our recent studies on divinyl chlorophylls functioning in unique marine picoplankton Prochlorococcus sp. (1) Essential physicochemical properties of divinyl chlorophylls are compared with those of monovinyl chlorophylls; separation by normal-phase and reversed-phase high-performance liquid chromatography with isocratic eluent mode, absorption spectra in four organic solvents, fluorescence information (emission spectra, quantum yields, and life time), circular dichroism spectra, mass spectra, nuclear magnetic resonance spectra, and redox potentials. The presence of a mass difference of 278 in the mass spectra between [M+H]+ and the ions indicates the presence of a phytyl tail in all the chlorophylls. (2) Precise high-performance liquid chromatography analyses show divinyl chlorophyll a' and divinyl pheophytin a as the minor key components in four kinds of Prochlorococcus sp.; neither monovinyl chlorophyll a' nor monovinyl pheophytin a is detected, suggesting that the special pair in photosystem I and the primary electron acceptor in photosystem II are not monovinyl but divinyl-type chlorophylls. (3) Only Prochlorococcus sp. NIES-2086 possesses both monovinyl chlorophyll b and divinyl chlorophyll b, while any other monovinyl-type chlorophylls are absent in this strain. Monovinyl chlorophyll b is not detected at all in the other three strains. Prochlorococcus sp. NIES-2086 is the first example that has both monovinyl chlorophyll b as well as divinyl chlorophylls a/b as major chlorophylls.

Harvesting Far-Red Light by Chlorophyll f in Photosystems I and II of Unicellular Cyanobacterium strain KC1.

Cells of a unicellular cyanobacterium strain KC1, which were collected from Japanese fresh water Lake Biwa, formed chlorophyll (Chl) f at 6.7%, Chl a' at 2.0% and pheophytin a at 0.96% with respect to Chl a after growth under 740 nm light. The far-red-acclimated cells (Fr cells) formed extra absorption bands of Chl f at 715 nm in addition to the major Chl a band. Fluorescence lifetimes were measured. The 405-nm laser flash, which excites mainly Chl a in photosystem I (PSI), induced a fast energy transfer to multiple fluorescence bands at 720-760 and 805 nm of Chl f at 77 K in Fr cells with almost no PSI-red-Chl a band. The 630-nm laser flash, which mainly excited photosystem II (PSII) through phycocyanin, revealed fast energy transfer to another set of Chl f bands at 720-770 and 810 nm as well as to the 694-nm Chl a fluorescence band. The 694-nm band did not transfer excitation energy to Chl f. Therefore, Chl a in PSI, and phycocyanin in PSII of Fr cells transferred excitation energy to different sets of Chl f molecules. Multiple Chl f forms, thus, seem to work as the far-red antenna both in PSI and PSII. A variety of cyanobacterial species, phylogenically distant from each other, seems to use a Chl f antenna in far-red environments, such as under dense biomats, in colonies, or under far-red LED light.

Site-directed mutagenesis of amino acid residues of D1 protein interacting with phosphatidylglycerol affects the function of plastoquinone QB in photosystem II.

Recent X-ray crystallographic analysis of photosystem (PS) II at 1.9-Å resolution identified 20 lipid molecules in the complex, five of which are phosphatidylglycerol (PG). In this study, we mutagenized amino acid residues S232 and N234 of D1, which interact with two of the PG molecules (PG664 and PG694), by site-directed mutagenesis in Synechocystis sp. PCC 6803 to investigate the role of the interaction in PSII. The serine and asparagine residues at positions 232 and 234 from the N-terminus were mutagenized to alanine and aspartic acid, respectively, and a mutant carrying both amino acid substitutions was also produced. Although the obtained mutants, S232A, N234D, and S232AN234D, exhibited normal growth, they showed decreased photosynthetic activities and slower electron transport from QA to QB than the control strain. Thermoluminescence analysis suggested that this slower electron transfer in the mutants was caused by more negative redox potential of QB, but not in those of QA and S2. In addition, the levels of extrinsic proteins, PsbV and PsbU, were decreased in PSII monomer purified from the S232AN234D mutant, while that of Psb28 was increased. In the S232AN234D mutant, the content of PG in PSII was slightly decreased, whereas that of monogalactosyldiacylglycerol was increased compared with the control strain. These results suggest that the interactions of S232 and N234 with PG664 and PG694 are important to maintain the function of QB and to stabilize the binding of extrinsic proteins to PSII.

Photosynthesis of root chloroplasts developed in Arabidopsis lines overexpressing GOLDEN2-LIKE transcription factors.

In plants, genes involved in photosynthesis are encoded separately in nuclei and plastids, and tight cooperation between these two genomes is therefore required for the development of functional chloroplasts. Golden2-like (GLK) transcription factors are involved in chloroplast development, directly targeting photosynthesis-associated nuclear genes for up-regulation. Although overexpression of GLKs leads to chloroplast development in non-photosynthetic organs, the mechanisms of coordination between the nuclear gene expression influenced by GLKs and the photosynthetic processes inside chloroplasts are largely unknown. To elucidate the impact of GLK-induced expression of photosynthesis-associated nuclear genes on the construction of photosynthetic systems, chloroplast morphology and photosynthetic characteristics in greenish roots of Arabidopsis thaliana lines overexpressing GLKs were compared with those in wild-type roots and leaves. Overexpression of GLKs caused up-regulation of not only their direct targets but also non-target nuclear and plastid genes, leading to global induction of chloroplast biogenesis in the root. Large antennae relative to reaction centers were observed in wild-type roots and were further enhanced by GLK overexpression due to the increased expression of target genes associated with peripheral light-harvesting antennae. Photochemical efficiency was lower in the root chloroplasts than in leaf chloroplasts, suggesting that the imbalance in the photosynthetic machinery decreases the efficiency of light utilization in root chloroplasts. Despite the low photochemical efficiency, root photosynthesis contributed to carbon assimilation in Arabidopsis. Moreover, GLK overexpression increased CO2 fixation and promoted phototrophic performance of the root, showing the potential of root photosynthesis to improve effective carbon utilization in plants.

Ubiquity and quantitative significance of detoxification catabolism of chlorophyll associated with protistan herbivory.

Chlorophylls are essential components of the photosynthetic apparati that sustain all of the life forms that ultimately depend on solar energy. However, a drawback of the extraordinary photosensitizing efficiency of certain chlorophyll species is their ability to generate harmful singlet oxygen. Recent studies have clarified the catabolic processes involved in the detoxification of chlorophylls in land plants, but little is understood about these strategies in aquatic ecosystem. Here, we report that a variety of heterotrophic protists accumulate the chlorophyll a catabolite 13(2),17(3)-cyclopheophorbide a enol (cPPB-aE) after their ingestion of algae. This chlorophyll derivative is nonfluorescent in solution, and its inability to generate singlet oxygen in vitro qualifies it as a detoxified catabolite of chlorophyll a. Using a modified analytical method, we show that cPPB-aE is ubiquitous in aquatic environments, and it is often the major chlorophyll a derivative. Our findings suggest that cPPB-aE metabolism is one of the most important, widely distributed processes in aquatic ecosystems. Therefore, the herbivorous protists that convert chlorophyll a to cPPB-aE are suggested to play more significant roles in the modern oceanic carbon flux than was previously recognized, critically linking microscopic primary producers to the macroscopic food web and carbon sequestration in the ocean.

An overview on chlorophylls and quinones in the photosystem I-type reaction centers.

Minor but key chlorophylls (Chls) and quinones in photosystem (PS) I-type reaction centers (RCs) are overviewed in regard to their molecular structures. In the PS I-type RCs, the prime-type chlorophylls, namely, bacteriochlorophyll (BChl) a' in green sulfur bacteria, BChl g' in heliobacteria, Chl a' in Chl a-type PS I, and Chl d' in Chl d-type PS I, function as the special pairs, either as homodimers, (BChl a')(2) and (BChl g')(2) in anoxygenic organisms, or heterodimers, Chl a/a' and Chl d/d' in oxygenic photosynthesis. Conversions of BChl g to Chl a and Chl a to Chl d take place spontaneously under mild condition in vitro. The primary electron acceptors, A (0), are Chl a-derivatives even in anoxygenic PS I-type RCs. The secondary electron acceptors are naphthoquinones, whereas the side chains may have been modified after the birth of cyanobacteria, leading to succession from menaquinone to phylloquinone in oxygenic PS I.

Purification and characterization of photosystem I complex from Synechocystis sp. PCC 6803 by expressing histidine-tagged subunits.

We generated Synechocystis sp. PCC 6803 strains, designated F-His and J-His, which express histidine-tagged PsaF and PsaJ subunits, respectively, for simple purification of the photosystem I (PSI) complex. Six histidine residues were genetically added to the C-terminus of the PsaF subunit in F-His cells and the N-terminus of the PsaJ subunit in J-His cells. The histidine residues introduced had no apparent effect on photoautotrophic growth of the cells or the activity of PSI and PSII in thylakoid membranes. PSI complexes could be simply purified from the F-His and J-His cells by Ni2+-affinity column chromatography. When thylakoid membranes corresponding to 20 mg chlorophyll were used, PSI complexes corresponding to about 7 mg chlorophyll could be purified in both strains. The purified PSI complexes could be separated into monomers and trimers by ultracentrifugation in glycerol density gradient and high activity was recorded for trimers isolated from the F-His and J-His strains. Blue-Native PAGE and SDS-PAGE analysis of monomers and trimers indicated the existence of two distinct monomers with different subunit compositions and no contamination of PSI with other complexes, such as PSII and Cyt b(6)f. Further analysis of proteins and lipids in the purified PSI indicated the presence of novel proteins in the monomers and about six lipid molecules per monomer unit in the trimers. These results demonstrate that active PSI complexes can be simply purified from the constructed strains and the strains are very useful tools for analysis of PSI.

Unique photosystems in Acaryochloris marina.

A short overview is given on the discovery of the chlorophyll d-dominated cyanobacterium Acaryochloris marina and the minor pigments that function as key components therein. In photosystem I, chlorophyll d', chlorophyll a, and phylloquinone function as the primary electron donor, the primary electron acceptor and the secondary electron acceptor, respectively. In photosystem II, pheophytin a serves as the primary electron acceptor. The oxidation potential of chlorophyll d was higher than that of chlorophyll a in vitro, while the oxidation potential of P740 was almost the same as that of P700. These results help us to broaden our view on the questions about the unique photosystems in Acaryochloris marina.

Effects of the lack of phosphatidylglycerol on the donor side of photosystem II.

Our previous studies with the pgsA mutant of the cyanobacterium Synechocystis sp. PCC6803 (hereafter termed pgsA mutant), which is defective for the biosynthesis of phosphatidylglycerol (PG), revealed an important role for PG in the electron acceptor side of photosystem II (PSII), especially in the electron transport between plastoquinones Q(A) and Q(B). This study now shows that PG also plays an important role in the electron donor side of PSII, namely, the oxygen-evolving system. Analyses of purified PSII complexes indicated that PSII from PG-depleted pgsA mutant cells sustained only approximately 50% of the oxygen-evolving activity compared to wild-type cells. Dissociation of the extrinsic proteins PsbO, PsbV, and PsbU, which are required for stabilization of the manganese (Mn) cluster, followed by the release of a Mn atom, was observed in PSII of the PG-depleted mutant cells. The released PsbO rebound to PSII when PG was added back to the PG-depleted mutant cells, even when de novo protein synthesis was inhibited. Changes in photosynthetic activity of the PG-depleted pgsA mutant cells induced by heat treatment or dark incubation resembled those of DeltapsbO, DeltapsbV, and DeltapsbU mutant cells. These results suggest that PG plays an important role in binding extrinsic proteins required for sustaining a functional Mn cluster on the donor side of PSII.

Redox potential of chlorophyll d in vitro.

Chlorophyll (Chl) d is a major chlorophyll in a novel oxygenic prokaryote Acaryochloris marina. Here we first report the redox potential of Chl d in vitro. The oxidation potential of Chl d was +0.88 V vs. SHE in acetonitrile; the value was higher than that of Chl a (+0.81 V) and lower than that of Chl b (+0.94 V). The oxidation potential order, Chl b>Chl d>Chl a, can be explained by inductive effect of substituent groups on the conjugated pi-electron system on the macrocycle. Corresponding pheophytins showed the same order; Phe b (+1.25 V)>Phe d (+1.21 V)>Phe a (+1.14 V), but the values were significantly higher than those of Chls, which are rationalized in terms of an electron density decrease in the pi-system by the replacement of magnesium with more electronegative hydrogen. Consequently, oxidation potential of Chl a was found to be the lowest among Chls and Phes. The results will help us to broaden our views on photosystems in A. marina.

Lipids in oxygen-evolving photosystem II complexes of cyanobacteria and higher plants.

Lipids in dimeric photosystem II complexes prepared from two species of cyanobacteria, Thermosynechococcus vulcanus and Synechocystis sp. PCC6803, and two higher plants, spinach and rice, were analyzed to determine how many lipid molecules and what class of lipids are present in the photosystem II complexes. It was estimated that 27, 20, 8, and 7 lipid molecules per monomer are bound to the dimeric photosystem II complexes of T. vulcanus, Synechocystis, spinach, and rice, respectively. In each of the organisms, the lipid composition of the photosystem II complexes was quite different from that of the thylakoid membranes used for preparation of the complexes. The content of phosphatidylglycerol in the photosystem II complexes of each organism was much higher than that in the thylakoid membranes. Phospholipase A2 treatment of the photosystem II complexes of Synechocystis that degraded phosphatidylglycerol resulted in impairment of QB-mediated but not QA-mediated electron transport. These findings suggest that phosphatidylglycerol plays important roles in the electron transport at the QB-binding site in photosystem II complexes.

Unique proteasome subunit Xrpn10c is a specific receptor for the antiapoptotic ubiquitin-like protein Scythe.

The Rpn10 subunit of the 26S proteasome can bind to polyubiquitinoylated and/or ubiquitin-like proteins via ubiquitin-interacting motifs (UIMs). Vertebrate Rpn10 consists of five distinct spliced isoforms, but the specific functions of these variants remain largely unknown. We report here that one of the alternative products of Xenopus Rpn10, named Xrpn10c, functions as a specific receptor for Scythe/BAG-6, which has been reported to regulate Reaper-induced apoptosis. Deletional analyses revealed that Scythe has at least two distinct domains responsible for its binding to Xrpn10c. Conversely, an Xrpn10c has a UIM-independent Scythe-binding site. The forced expression of a Scythe mutant protein lacking Xrpn10c-binding domains in Xenopus embryos induces inappropriate embryonic death, whereas the wild-type Scythe did not show any abnormality. The results indicate that Xrpn10c-binding sites of Scythe act as an essential segment linking the ubiquitin/proteasome machinery to the control of proper embryonic development.

Minor but key chlorophylls in photosystem II.

A 'metal-free' chlorophyll (Chl) a, pheophytin (Phe) a, functions as the primary electron acceptor in PS II. On the basis of Phe a/PS II = 2, Phe a content is postulated as an index for estimation of the stoichiometry of pigments and photosystems. We found Phe a in a Chl d-dominant cyanobacterium Acaryochloris marina, whereas Phe d was absent. The minimum Chl a:Phe a ratio was 2:2, indicating that the primary electron donor is Chl a, accessory is Chl d, and the primary electron acceptor is Phe a in PS II of A. marina. Chl d was artificially formed by the treatment of Chl a with papain in aqueous organic solvents. Further, we will raise a key question on the mechanisms of water oxidation in PS II.

The secondary electron acceptor of photosystem I in Gloeobacter violaceus PCC 7421 is menaquinone-4 that is synthesized by a unique but unknown pathway.

The secondary electron acceptor of photosystem (PS) I in the cyanobacterium Gloeobacter violaceus PCC 7421 was identified as menaquinone-4 (MQ-4) by comparing high performance liquid chromatograms and absorption spectra with an authentic compound. The MQ-4 content was estimated to be two molecules per one molecule of chlorophyll (Chl) a', a constituent of P700. Comparative genomic analyses showed that six of eight men genes, encoding phylloquinone/MQ biosynthetic enzymes, are missing from the G. violaceus genome. Since G. violaceus clearly synthesizes MQ-4, the combined results indicate that this cyanobacterium must have a novel pathway for the synthesis of 1,4-dihydroxy-2-naphthoic acid.

Use of glycopeptidolipid core antigen for serodiagnosis of mycobacterium avium complex pulmonary disease in immunocompetent patients.

We report the development of a serodiagnostic method for Mycobacterium avium complex (MAC) disease with an enzyme immunoassay (EIA) with the MAC-specific glycopeptidolipid (GPL) core as the antigen. In this study, we confirmed by EIA that the GPL core antibody was in the sera of immunocompetent patients with MAC disease. The EIA for quantifying the GPL core antibody was evaluated as a clinical tool for serodiagnosis of pulmonary MAC disease. A significant increase in GPL core antibodies (immunoglobulins G, A, and M) was detected in sera of patients with MAC pulmonary diseases when they were compared to patients who were colonized with MAC, patients with Mycobacterium kansasii disease or tuberculosis, and healthy subjects. The sensitivities and specificities of the GPL core-based EIA for diagnosis of MAC pulmonary disease were 72.6% and 92.2%, respectively, for IgG, 92.5% and 95.1%, respectively, for IgA, and 78.3% and 91.0%, respectively, for IgM. The best sensitivity and specificity were obtained by measuring immunoglobulin A antibodies against GPL core antigen. The level of GPL core antibodies reflected disease activity, since it decreased in cured MAC patients who had responded to chemotherapy. Measurement of serum antibodies against GPL core is useful for both diagnosis and assessment of disease activity in MAC disease of the lung.

Identification of the primary electron donor in PS II of the Chl d-dominated cyanobacterium Acaryochloris marina.

The primary electron donor of photosystem (PS) II in the chlorophyll (Chl) d-dominated cyanobacterium Acaryochloris marina was confirmed by delayed fluorescence (DF) and further proved by pigment contents of cells grown under several light intensities. The DF was found only in the Chl a region, identical to Synechocystis sp. PCC 6803, and disappeared following heat treatment. Pigment analyses indicated that at least two Chl a molecules were present per each two pheophytin a molecules, and these Chl a molecules are assigned to P(D1) and P(D2). These findings clearly indicate that Chl a is required for water oxidation in PS II.