Phylogeographic History of Endangered Hokuriku Salamander, Hynobius takedai (Amphibia: Caudata).

Knowledge of the phylogeographic history of organisms is valuable for understanding their evolutionary processes. To the best of our knowledge, the phylogeographic structure of Hokuriku salamander, Hynobius takedai, an endangered species, remains unclear. This study aimed to elucidate the phylogeographic history of H. takedai, which is expected to be strongly influenced by paleogeographic events. Phylogenetic analysis based on partial sequences of the mitochondrial DNA cytochrome b gene confirmed the genetic independence of H. takedai, and the divergence time with closely related species was estimated to be from the Late Pliocene to the Early Pleistocene. In the phylogenetic tree, two clades were identified within H. takedai, and their haplotypes were found in samples collected from the west and east of the distribution range. These intraspecific divergences were strongly influenced by geohistorical subdivisions of the current major distribution areas in the Middle Pleistocene. One clade was further subdivided and its formation may have been influenced by sea level changes in the Late Pleistocene.

Nanoparticle-Based Tough Polymers with Crack-Propagation Resistance.

Although thin elastomer films of polymer nanoparticles are regarded as environmentally friendly materials, the low mechanical strength of the films limits their use in various applications. In the present study, we investigated the fracture resistance of latex films composed of acrylic nanoparticles where a small quantity of a rotaxane crosslinker was introduced. In contrast to conventional nanoparticle-based elastomers, the latex films composed of the rotaxane-crosslinked nanoparticles exhibited unusual crack propagation behavior; the direction of crack propagation changed from a direction parallel to the crack to one perpendicular to the crack, resulting in an increase in tear resistance. These findings will help to broaden the scope of design of new types of tough polymers composed of environmentally friendly polymer nanoparticles.

Asymmetric Syn-Selective Vinylogous Addition of Butenolides to Chromones via Al-Li-BINOL Catalysis.

A gram-scale syn-selective asymmetric vinylogous addition of butenolides to chromones, catalyzed by an Al-Li-BINOL (ALB) complex, was developed in this study. For various combinations of substrates, the observed diastereoselectivity approached 20:1 with 84-98% ee. This protocol is complementary to previously reported ones and improves the selectivity for several chromones. This methodology can be applied to a quinolone substrate, affording another type of heterocyclic scaffolds substituted with five-membered lactones. Computational studies support the role of ALB as a bifunctional catalyst in this reaction and provide insights into the origin of the observed stereoselectivity.

Landscape Genetic Analysis for the Japanese Wild Boar in the Early Expanding Stage in the Hokuriku Region of Japan.

As a contribution to improving management of the Japanese wild boar (Sus scrofa leucomystax), which has recently expanded its range and is having some negative effects on the ecosystem, we conducted a landscape genetic study using individual-based genetic analysis and multiple landscape elements to elucidate its dispersal patterns in the early stage of its expansion. Microsatellite DNA analysis of Japanese wild boars in the Hokuriku region of Japan revealed the existence of two ancestral genetic clusters, that they had migrated via different pathways, and that they were inadequately admixed. We also inferred the most suitable habitats for Japanese wild boar using MaxEnt and concluded that lower elevation and snowfall may favor the occurrence of wild boar individuals. Landscape genetic analysis indicated regional differences in Japanese wild boar dispersal patterns, according to the spatial heterogeneity of genetic features and landscape elements. On the western side of the study area, where individuals with a high frequency of one of two ancestral clusters were more abundant, significant effects of isolation by distance and resistance due to the above two landscape factors were detected, suggesting unidirectional dispersion influenced by the alpine landscape. In contrast, on the eastern side, there was indication of resistance to dispersal of individuals predominantly possessing another ancestral cluster, suggesting the influence of irregularly arranged suitable habitats due to the complexity of the mountainous terrain. Based on our findings, we conclude that Japanese wild boar dispersal patterns may be influenced by landscape elements, such as alpine mountains.

Targeting the ATG5-ATG16L1 Protein-Protein Interaction with a Hydrocarbon-Stapled Peptide Derived from ATG16L1 for Autophagy Inhibition.

Selective modulation of autophagy is a promising therapeutic strategy, especially for cancer treatment. However, the lack of specific autophagy inhibitors limits this strategy. The formation of the ATG12-ATG5-ATG16L1 complex is essential for targeting the ATG12-ATG5 conjugate to proper membranes and to generate LC3-II for the progression of autophagy. Thus, targeting ATG5-ATG16L1 protein-protein interactions (PPIs) might inhibit early stage autophagy with high specificity. In this paper, we report that a stapled peptide derived from ATG16L1 exhibits potent binding affinity to ATG5, striking resistance to proteolysis, and significant autophagy inhibition activities in cells.

Clarification of Surface Deswelling of Thermoresponsive Microgels by Electrophoresis.

Although many investigations of thermoresponsive microgels have been reported, their surface properties, which are crucial in colloid science, are still not fully understood. In this study, microgels with surface-localized charged groups were synthesized by precipitation polymerization, and their electrophoretic behaviors were analyzed using a modified version of Ohshima's equation to obtain two surface properties of the soft particles: the softness parameter and the surface charge density. This systematic evaluation allows us to discuss the thermoresponsiveness of the overall microgels and their surfaces separately. Furthermore, the validity of the surface properties obtained from electrophoresis was verified by comparing them with the results of seeded emulsion polymerization in the presence of the microgels and the force-indentation curves obtained via high-speed atomic force microscopy (HS-AFM).

Virucidal effect of monogalactosyl diacylglyceride from a green microalga, Coccomyxa sp. KJ, against clinical isolates of SARS-CoV-2 as assessed by a plaque assay.

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of coronavirus disease 2019 (COVID-19) and is capable of human-to-human transmission and rapid global spread. Thus, the establishment of high-quality viral detection and quantification methods, and the development of anti-SARS-CoV-2 agents are critical. METHODS: Here, we present the rapid detection of infectious SARS-CoV-2 particles using a plaque assay with 0.5% agarose-ME (Medium Electroosmosis) as an overlay medium. RESULTS: The plaques were capable of detecting the virus within 36-40 h post-infection. In addition, we showed that a monogalactosyl diacylglyceride isolated from a microalga (Coccomyxa sp. KJ) could inactivate the clinical isolates of SARS-CoV-2 in a time- and concentration-dependent manner. CONCLUSIONS: These results would allow rapid quantification of the infectious virus titers and help develop more potent virucidal agents against SARS-CoV-2.

Concise and Stereodivergent Approach to Chromanone Lactones through Copper-Catalyzed Asymmetric Vinylogous Addition of Siloxyfurans to 2-Ester-Substituted Chromones.

Vicinal oxygen-containing tetra- and tri-substituted stereocenters exist widely in chromanone lactone and tetrahydroxanthone natural products. Their enantioselective construction in a single step remains elusive and poses a formidable challenge for chemical synthesis. Here, we report the first copper(I)-catalyzed asymmetric vinylogous additions of siloxyfurans to 2-ester-substituted chromones, which enable concise and enantioselective assembly of chromanone lactones. Both syn and anti adducts can be accessed with excellent diastereo- and enantioselectivity by judicious choice of the chiral ligands. Our approach allowed for the efficient synthesis of (-)-blennolide B with precise stereochemical control, which provides a formal synthesis of secalonic acid A.

Catalytic Asymmetric Total Synthesis of Leucinostatin A.

This review describes our efforts toward achieving catalytic asymmetric total synthesis of leucinostatin A, a compound that interferes with the tumor-stroma interaction. The synthesis utilizes four catalytic asymmetric reactions, including direct-type reactions exemplified by high atom-economy, and three C-C bond forming reactions. Thorough analysis of the NMR data, HPLC profiles, and biologic activity led us to unambiguously revise the absolute configuration regarding the 6-position of the AHMOD residue side chain from S (reported) to R. Other examples of previously reported important studies on the stereoselective synthesis of HyLeu and AHMOD are also described.

Hybridization of Two Species of Japanese Toads, Bufo torrenticola and Bufo japonicus formosus, in the Central Part of Japan.

Interspecific hybridization between two species of Japanese toads, Bufo torrenticola (Bt) and Bufo japonicus formosus (Bjf), was not thought to have occurred due to the differences in their spawning habitats, although their hybridization was reported by previous research in a limited area. Such hybridization could have pivotal effects, such as genetic admixture, on Bt, which has a limited distribution and habitat. In this study, to clarify the details of hybridization, a total of 192 individuals were collected from multiple parapatric regions and an only Bjf allopatric region and analyzed based on morphology, mtDNA sequences, and nuclear DNA microsatellite loci. Each individual was identified based on morphological type and mtDNA lineage, and two mismatched combinations, Bt or an intermediate morphological type and the Bjf mtDNA lineage, were detected. In particular, the combination of Bt type and Bjf lineage was dominant in parapatric regions, and it was considered that asymmetric hybridization in which Bjf became a matriline had occurred. In addition, a Bayesian clustering method based on the microsatellite loci was conducted to detect a genetic admixture of the two toad species. Individuals representing a combination of the Bt type and Bjf lineage in the parapatric regions were largely assigned to the Bt cluster or equally to both clusters. These results indicate that backcross with Bt has been repeated, and therefore the traits of Bt might be maintained in this study.

Inhibition of mitochondria ATP synthase suppresses prostate cancer growth through reduced insulin-like growth factor-1 secretion by prostate stromal cells.

Modulation of prostate stromal cells (PrSCs) within tumor tissues is gaining attention for the treatment of solid tumors. Using our original in vitro coculture system, we previously reported that leucinostatin (LCS)-A, a peptide mycotoxin, inhibited prostate cancer DU-145 cell growth through reduction of insulin-like growth factor 1 (IGF-I) expression in PrSCs. To further obtain additional bioactive compounds from LCS-A, we designed and synthesized a series of LCS-A derivatives as compounds that target PrSCs. Among the synthesized LCS-A derivatives, LCS-7 reduced IGF-I expression in PrSCs with lower toxicity to PrSCs and mice than LCS-A. As LCS-A has been suggested to interact with mitochondrial adenosine triphosphate (ATP) synthase, a docking study was performed to elucidate the mechanism of reduced IGF-I expression in the PrSCs. As expected, LCS-A and LCS-7 directly interacted with mitochondrial ATP synthase, and like LCS-A and LCS-7, other mitochondrial ATP synthase inhibitors also reduced the expression of IGF-I by PrSCs. Furthermore, LCS-A and LCS-7 significantly decreased the growth of mouse xenograft tumors. Based on these data, we propose that the mitochondrial ATP synthases-IGF-I axis of PrSCs plays a critical role on cancer cell growth and inhibition could be a potential anticancer target for prostate cancer.

Two-step yielding behavior of densely packed microgel mixtures with chemically dissimilar surfaces and largely different sizes.

Steady-state flow and elastic behavior is investigated for the moderately concentrated binary suspensions of soft microgels (pastes) with chemically dissimilar surfaces, and various degrees of size- and stiffness disparities. The pastes of poly(N-isopropyl acrylamide) (N) and poly(N-isopropyl methacrylamide) (NM) microgels with different values of yield strain γc (γNc > γNMc) are employed as the components. For the single microgel pastes (φ ≈ 1 where φ is apparent volume fraction), the values of γc are governed by the chemical species of constituent polymer in microgel surface whereas γc is insensitive to cross-link density and particle size. We demonstrate that the binary N/NM pastes with large size disparity (RN/NM = DN/DNM < 0.26 where D is the microgel diameter) at low φN (φN: weight fraction of small N microgels) exhibit the peculiarities in several rheological aspects, i.e., the two-step yielding in steady-state flow, and their values of γc and equilibrium shear modulus (G0) being equivalent to those of the single large NM microgel paste. These peculiarities are attributed to the characteristic packing resulting from large size disparity in which all or almost of the small N microgels tend to be accommodated in the gap between the large NM microgels even in moderately concentrated state. This characteristic packing substantially masks the contribution of the small N microgels at low φN, explaining the φN-independent G0 and γc as well as the first yielding governed solely by the large NM microgels. The second yielding results from the emerged contribution of the small N microgels expelled out from the gap by the positional rearrangements after the first yielding. The binary homo-N/N pastes with the similarly large size disparity at low φsmall also exhibit the φsmall-independent values of G0, but they show one-step yielding, indicating that the two-step yielding requires not only sufficiently large size disparity but also chemical dissimilarity (different values of γc) between the two components.

Hydrophobic Monomers Recognize Microenvironments in Hydrogel Microspheres during Free-Radical-Seeded Emulsion Polymerization.

The three-dimensional structure of nanocomposite microgels was precisely determined by cryo-electron micrography. Several nanocomposite microgels that differ with respect to their nanocomposite structure, which were obtained from seeded emulsion polymerization in the presence of microgels, were used as model nanocomposite materials for cryo-electron micrography. The obtained three-dimensional segmentation images of these nanocomposite microgels provide important insights into the interactions between the hydrophobic monomers and the microgels, that is, hydrophobic styrene monomers recognize molecular-scale differences in polarity within the microgels during the emulsion polymerization. This result led to the formation of unprecedented multi-layered nanocomposite microgels, which promise substantial potential in colloidal applications.

Hydrogen Isotope Absorption in Unary Oxides and Nitrides with Anion Vacancies and Substitution.

The absorption states of hydrogen isotopes in various ceramic materials were investigated by density functional theory. For pristine ceramic materials, main-group oxides do not form any bond with a hydrogen atom. However, transition metal oxides form hydroxyl groups and absorb hydrogen atoms. Main-group and transition metal nitrides form ionic bonds between a hydrogen atom and the surrounded cation. For anion-deficient ceramic materials, hydrogen atoms are negatively charged because of excess electrons induced by anion vacancies, and ionic bonds form with the surrounded cation, which stabilizes the hydrogen absorption state. N substitutional doping into oxides introduces an electron hole, while O substitutional doping into the nitrides introduces an excess of electrons. Therefore, hydrogen isotopes form covalent bonds in N-substituted oxides, and form hydride ions in O-substituted nitrides. Thus, Al2 O3 , SiO2 , CrN, and TiN are promising materials as hydrogen permeation barriers.

Enzymatic syntheses of novel carbocyclic scaffolds with a 6,5 + 5,5 ring system by squalene-hopene cyclase.

Squalene-hopene cyclase (SHC) converts acyclic squalene 1 into the 6,6,6,6,5-fused pentacyclic triterpenes hopene and hopanol. Previously, we reported the polycyclization products 14-17 of 27-norsqualene (13a) and 28-norsqualene (13b) by SHC, and suggested the importance of Me-27 of 1 for the normal polycyclization pathway. To further ensure the theory, (3R,S)-27-noroxidosqualenes (18 and 19) were incubated, and the structures of products 20-25 thus obtained prompted us to reinvestigate the SHC reaction of 13a (13b). One new product 29, composed of a 6,5 + 5,5 ring system with 13α-H and 17α-H, was obtained from 13a in addition to both the previously isolated products 14-17 and the 6,6,6,5-fused tetracyclic dammarenyl compounds, which were overlooked before. We propose the name "nor-allodammarane" for this novel tetracyclic 6,5 + 5,5 ring system and the name "nor-allogammacerane" for the pentacyclic 6,5 + 5,5 + 6 ring system. The stereochemistry of 29 indicated that 13a folded in the following chair-boat-boat-boat conformation: 10α-H, 11ß-H; 14α-H, 15ß-Me; 18α-H and 19ß-Me, which further allowed us to predict the configuration of 20R for 14 and that of 20S for 15. Substrates 18 and 19 were also cyclized only into allodammarane scaffolds 20-25, and all the structures of 20-25 further indicated that 18 and 19 also folded in the same conformation as 13a, providing further evidence that Me-27 groups of 1 and oxidosqualene are essential for the normal polycyclization pathway by SHC.

Chemical Studies on Bioactive Natural Products Directed toward Development of Novel Antiinfective and Anticancer Medicines.

Natural products are still rich sources of clinically used medicines and lead compounds for them. This review summarizes chemical studies carried out by the author on natural products of microorganism origin, many of which were discovered at the Institute of Microbial Chemistry (BIKAKEN). Caprazamycin B is a liponucleoside antibiotic from which CPZEN-45, an antituberculosis agent with a unique mode of action, was developed. Intervenolin and leucinostatin A exert antiproliferative activity toward tumor cells in the presence of the corresponding stromal cells, which implies that the primary molecular targets of these molecules should be related to growth signals from normal (stromal) cells. Details of the endeavors to establish efficient synthetic routes to these compounds which accelerated structure-activity relationship studies and further evaluation of biological activity are described.

Hydrogel Microellipsoids that Form Robust String-Like Assemblies at the Air/Water Interface.

Soft colloidal particles such as hydrogel microspheres assemble at air/water or oil/water interfaces, where the soft colloids are highly deformed and their surface polymer chains are highly entangled with each other. Herein, we report the formation of robust one-dimensional, string-like colloidal assemblies through self-organization of hydrogel microspheres with shape anisotropy at the air/water interface of sessile droplets. Shape-anisotropic hydrogel microspheres were synthesized via two-step polymerization, whereby a hydrogel shell was formed onto preformed rigid microellipsoids. The shape anisotropy of the hydrogel microspheres was confirmed by transmission electron microscopy and high-speed atomic force microscopy as well as by light-scattering measurements. The present findings are crucial for the understanding of natural self-organization phenomena, where "softness" influences microscopic assembled structures such as those of Nostoc bacteria.

Strictly Conserved Residues in Euphorbia tirucalli ß-Amyrin Cyclase: Trp612 Stabilizes Transient Cation through Cation-π Interaction and CH-π Interaction of Tyr736 with Leu734 Confers Robust Local Protein Architecture.

The functions of Trp612, Leu734, and Tyr736 of Euphorbia tirucalli ß-amyrin synthase were examined. The aliphatic variants (Ala, Val, Met) of Trp612 showed almost no activity, but the aromatic variants exhibited high activities: 12.5 % of the wild-type activity for the W612H variant, 43 % for W612F, and 63 % for W612Y. That is, the enzymatic activities of the variants increased in proportion to the increase in π-electron density. Thus, the major function of Trp612 is to stabilize transient cations through a cation-π interaction. The Phe and Tyr variants caused a distorted folding conformation, especially at the E-ring site, which generated the aberrantly cyclized products germanicol and lupeol. The L734G and L734A variants exhibited significantly decreased activities but yielded taraxerol in a high production ratio. The Val, Ile, and Met variants showed markedly high activities (56-78 % of wild-type activity); therefore, appropriate steric bulk is required at this position. The aliphatic variants of Tyr736 showed markedly decreased activities, but the Phe mutant exhibited high activity (67 %), which indicates that the π electrons are critical for catalysis. Homology modeling indicated that Tyr736 and Leu734 are perpendicular to the substrate and are situated face to face, which suggests that a CH-π interaction occurs between Tyr736 and Leu734, reinforcing the protein architecture, and that Tyr736 cannot stabilize cationic intermediates through a cation-π interaction.

Direct Catalytic Asymmetric Aldol Reaction of Thioamide with an α-Vinyl Appendage.

The direct catalytic asymmetric aldol reaction is an emerging catalytic methodology that provides atom-economical access to functionalized chiral building blocks. Thioamides are useful aldol donors due to their high-fidelity chemoselective enolization and divergent post-aldol transformations. Herein we describe the incorporation of an α-vinyl appendage on a thioamide, which expands the utility of aldol adducts for natural product synthesis. This vinylated thioamide was not accommodated under the previously identified catalyst settings, but the newly developed catalytic conditions furnished aldol products containing the pendant vinyl group.

Thermally Stimulated Light Reflection and Photoluminescence of BaTiO3.

Perovskites have been attracting attention because of their considerable luminescence properties. A conventional perovskite such as BaTiO3 has no intrinsic photoluminescence. Doping with rare metals, nanocrystallization, and addition of organometallic halides induce significant photoluminescence and photovoltages. Here, we report anomalous light reflection and photoluminescence of BaTiO3 on heating. Light absorption shifted from the near-ultraviolet region to the visible region on heating. The small emission peaks at around 400-500 nm disappeared and new peaks appeared above 800 nm; the quantum yields of these peaks were less than 1% and more than 7%, respectively.