Proceedings of the Japan Academy. Series B, Physical and Biological Sciences最新文献

Adherent eukaryotic cells typically exhibit amoeboid locomotion through actin polymerization and bleb-driven mechanisms. However, testate amoebae, which enclose their bodies within a shell, exhibit variation in these locomotion types. This study focused on Arcella, a representative testate amoeba that pulls its shell using multiple pseudopods extending from a single aperture on the ventral side. Arcella is found in peatlands and freshwater, where it adapts its movement to various substrates. We characterized its movement on glass as well as hard, and soft gel substrates through detailed observation. The results indicated a higher randomness in motion on the soft gel, which was influenced by the pseudopodial elongation direction. Additionally, we evaluated the relationship between movement direction and traction stress. The dipole moment of the traction stress field determined the axis of motion, whereas quadrupole moments were correlated with forward and lateral movements. Although some relationships between multipole moments and velocity were shared with other cells, Arcella exhibited unique characteristics in its movement mechanism, which likely occurred due to its use of multiple pseudopods alongside its shell.

Spider silk has garnered significant attention across diverse research fields because of its remarkable physical and biological properties, which have driven extensive efforts to develop materials and fabrication processes that replicate its unique characteristics. This review focuses on the structure of silk fibers and the mechanisms that underlie their formation, with an emphasis on the hierarchical organization that contributes to their outstanding performance. Additionally, the biodegradability of silk proteins and their degradation products are discussed, and their potential for sustainable material design are highlighted.

Nyctinasty, a circadian-regulated leaf movement observed in legumes, has long intrigued scientists. This study identified genus-specific endogenous chemical factors, leaf-closing factors (LCFs) and leaf-opening factors (LOFs), that control this rhythmic behavior. In Samanea saman, a model for nyctinasty, the LCF 12-hydroxyjasmonic acid glucoside induces leaf-folding by selectively targeting extensor motor cells and activating reactive oxygen species (ROS)-dependent K⁺ efflux via the SPORK2 channel. Functional analyses revealed that SPORK2 and the SsSLAH1/SsSLAH3 anion channel complex are key effectors in the regulation of leaf movement. Remarkably, SPORK2 also functions as a temperature-sensitive K⁺ channel, inactivating at low temperatures to mediate rain-induced leaf folding, a phenomenon underlying the nickname "rain tree". These findings provide a chemical entry point to dissect the molecular machinery of nyctinasty and reveal a previously unrecognized role for plant K⁺ channels in temperature sensing.

Advancements in living standards, medical technologies, and nutrition have contributed to the global increase in life expectancy. However, the widening gap between life expectancy and healthy life expectancy indicates that a growing population requires ongoing medical care and hospitalization. The development of a home-use telediagnostic system is a promising solution for improving the quality of life for patients and healthcare providers to extend a healthy lifespan and reduce the burden on clinicians. Such a system also holds the potential for rapid health assessments during emergency situations, where timely triage is critical. This study reviews recent progress in noninvasive, multimodal sensor patches capable of continuously monitoring vital signs and biomarkers via the skin. Furthermore, we explore the integration of machine learning for real-time, on-device data analysis as an edge system, enabling autonomous health feedback without reliance on the Internet. Although several technical challenges remain before practical implementation, these innovations may pave the way for a paradigm shift in conventional medical care.

This study assessed the feasibility of unconstrained deep-learning-based sleep stage classification using cardiorespiratory and body movement activities derived from piezoelectric sensors installed under a bed mattress. Heart and respiratory rates and their respective variabilities, cardiorespiratory coupling index, and body movement were simultaneously acquired through polysomnography (PSG) for 106 untreated participants with suspected sleep apnea. We used a bidirectional long short-term memory network to predict the five sleep stages using five different input feature combinations. The best performance was achieved with a model comprising six parameters, including cardiorespiratory variability features, with a balanced accuracy of 0.70 ± 0.05, Cohen's κ of 0.40 ± 0.11, and an F1 score of 0.63 ± 0.08. Deming regression and Bland-Altman analyses of the six major sleep parameters estimated by the model and those determined by PSG showed significant correlations (r = 0.426-0.781) with a low bias. These results demonstrate the effectiveness of the proposed approach and its potential to expand opportunities for in-home sleep monitoring.

M-COPA (1), which contains diene and 3-picolylamine moieties in its side chain and seven stereogenic centers in a multisubstituted octalin skeleton, strongly inhibits the growth of several cancer cell lines. Expecting the improvement of conformational flexibility of basic and coordinating 3-pyridylmethylamino group on M-COPA and its physical properties, we efficiently synthesized its amine analogs by replacing its amide group with an amino group through the Weinreb amide-type Horner-Wadsworth-Emmons reaction. The cytotoxic properties of 1 and its analogs were evaluated against NCI-H226, a lung cancer cell line, HeLa, a cervical cancer cell line, and GIST-T1, a gastrointestinal stromal tumor cell line. The evaluation results indicated that the structural alteration from amide moiety to amine moiety lowered the pharmacological activity but remained strong cytotoxicity.

Tetrodotoxin (TTX), the pufferfish toxin, has the potential to cause fatal food poisoning because of its potent voltage-gated sodium channel (Na_v) blocking activity. 4-epiTTX, 11-norTTX-6(S)-ol, and 11-oxoTTX are the major TTX analogues found in marine animals; thus, their chemical properties and biological activities should be determined. In this study, these three TTX analogues were purified to a high level (purity >97%) from pufferfish and newts. The ratios of the hemilactal to the 10,7-lactone forms were determined using ¹H NMR, and ¹³C NMR data were also obtained. 4-epiTTX underwent considerable transformation to TTX in physiological conditions. The Na_v blocking activity of these analogues was evaluated by whole-cell patch-clamp recording using a human Na_v1.2, colorimetric cell-based assay and mouse bioassay. The toxicity equivalency factors (TEFs setting TTX 1) of the three analogues were estimated; 4-epiTTX (0.06), 11-norTTX-6(S)-ol (0.02), and 11-oxoTTX (1.2) using patch-clamp recording, and 11-norTTX-6(S)-ol (0.50) and 11-oxoTTX (0.42) using the mouse bioassay. These data confirmed the low Na_v blocking activity of 4-epiTTX and high activity of 11-oxoTTX.

Renal counterbalance, involving compensatory hypertrophy of the healthy kidney and atrophy of the injured one, remains incompletely understood, particularly at the glomerular level. In this study, we employed NEP25 mice, which selectively express human CD25 in podocytes, enabling precise induction of unilateral podocyte injury through the administration of LMB2, a CD25-targeted immunotoxin. Using a two-kidney, one-nephropathy (2K1N) model, we demonstrated that asymmetric changes in renal blood flow and proteinuria, with histological and transcriptomic analyses uncovering distinct pathological and molecular features between the injured and contralateral healthy kidneys. Notably, an imbalance in intrarenal angiotensin (Ang) II levels was observed, and angiotensin-converting enzyme inhibition ameliorated the glomerular damage and restored perfusion. These findings indicate that local Ang II dysregulation is a key factor in renal counterbalance. Our study provides the first glomerulopathy-based experimental platform to dissect asymmetric renal adaptation, offering fundamental insight into the homeostatic mechanisms of renal function in health and disease.

The organization and dynamics of chromatin are critical for genome functions such as transcription and DNA replication/repair. Historically, chromatin was assumed to fold into the 30-nm fiber and progressively arrange into larger helical structures, as described in the textbook model. However, over the past 15 years, extensive evidence including our studies has dramatically transformed the view of chromatin from a static, regular structure to one that is more variable and dynamic. In higher eukaryotic cells, chromatin forms condensed yet liquid-like domains, which appear to be the basic unit of chromatin structure, replacing the 30-nm fiber. These domains maintain proper accessibility, ensuring the regulation of DNA reaction processes. During mitosis, these domains assemble to form more gel-like mitotic chromosomes, which are further constrained by condensins and other factors. Based on the available evidence, I discuss the physical properties of chromatin in live cells, emphasizing its viscoelastic nature-balancing local fluidity with global stability to support genome functions.

Aegilops tauschii Coss., a progenitor of bread wheat, is an important wild genetic resource for breeding. The species comprises three genetically defined lineages (TauL1, TauL2, and TauL3), each displaying valuable phenotypes in agronomic traits, including spike shape. In the present work, we studied the relationship between population structure and spike shape variation patterns using a collection of 249 accessions. f₄-statistics-based ancestry profiling confirmed the previously identified lineages and revealed a genetic component derived from TauL3 in the genomes of some southern Caspian and Transcaucasus TauL1 and TauL2 accessions. Spike shape variation patterns were analyzed using a convolutional neural network-based approach, trained on green and dry spike image datasets. This analysis showed that spike shape diversity is structured according to lineages and demonstrated the potential to distinguish the lineages based on spike shape. The implications of these findings for the origins of common wheat and the intraspecific taxonomy of Ae. tauschii are discussed.