Biophysics and Physicobiology最新文献

The high-speed atomic force microscopy (HS-AFM) is a unique and prominent method to observe structural dynamics of biomolecules at single molecule level at near-physiological condition. To achieve high temporal resolution, the probe tip scans the stage at high speed which can cause the so-called parachuting artifact in the HS-AFM images. Here, we develop a computational method to detect and remove the parachuting artifact in HS-AFM images using the two-way scanning data. To merge the two-way scanning images, we employed a method to infer the piezo hysteresis effect and to align the forward- and backward-scanning images. We then tested our method for HS-AFM videos of actin filaments, molecular chaperone, and duplex DNA. Together, our method can remove the parachuting artifact from the raw HS-AFM video containing two-way scanning data and make the processed video free from the parachuting artifact. The method is general and fast so that it can easily be applied to any HS-AFM videos with two-way scanning data.

To completely treat and ultimately prevent dementia, it is essential to elucidate its pathogenic mechanisms in detail. There are two major hypotheses for the pathogenesis of Alzheimer's dementia: the β-amyloid (Aβ) hypothesis and the tau hypothesis. The modified amyloid hypothesis, which proposes that toxic oligomers rather than amyloid fibrils are the essential cause, has recently emerged. Aβ peptides [Aβ(1-40) and Aβ(1-42)] form highly insoluble aggregates in vivo and in vitro. These Aβ aggregates contain many polymorphisms, whereas Aβ peptides are intrinsically disordered in physiological aqueous solutions without any compact conformers. Over the last three decades, solid-state nuclear magnetic resonance (NMR) has greatly contributed to elucidating the structure of each polymorph, while solution NMR has revealed the dynamic nature of the transient conformations of the monomer. Moreover, several methods to investigate the aggregation process based on the observation of magnetization saturation transfer have also been developed. The complementary use of NMR methods with cryo-electron microscopy, which has rapidly matured, is expected to clarify the relationship between the amyloid and molecular pathology of Alzheimer's dementia in the near future. This review article is an extended version of the Japanese article, Insights into the Mechanisms of Oligomerization/Fibrilization of Amyloid β Peptide from Nuclear Magnetic Resonance, published in SEIBUTSU BUTSURI Vol. 62, p. 39-42 (2022).

Two-photon excitation laser scanning microscopy (TPLSM) has provided many insights into the life sciences, especially for thick biological specimens, because of its superior penetration depth and less invasiveness owing to the near-infrared wavelength of its excitation laser light. This paper introduces our four kinds of studies to improve TPLSM by utilizing several optical technologies as follows: (1) A high numerical aperture objective lens significantly deteriorates the focal spot size in deeper regions of specimens. Thus, approaches to adaptive optics were proposed to compensate for optical aberrations for deeper and sharper intravital brain imaging. (2) TPLSM spatial resolution has been improved by applying super-resolution microscopic techniques. We also developed a compact stimulated emission depletion (STED) TPLSM that utilizes electrically controllable components, transmissive liquid crystal devices, and laser diode-based light sources. The spatial resolution of the developed system was five times higher than conventional TPLSM. (3) Most TPLSM systems adopt moving mirrors for single-point laser beam scanning, resulting in the temporal resolution caused by the limited physical speed of these mirrors. For high-speed TPLSM imaging, a confocal spinning-disk scanner and newly-developed high-peak-power laser light sources enabled approximately 200 foci scanning. (4) Several researchers have proposed various volumetric imaging technologies. However, most technologies require large-scale and complicated optical setups based on deep expertise for microscopic technologies, resulting in a high threshold for biologists. Recently, an easy-to-use light-needle-creating device was proposed for conventional TPLSM systems to achieve one-touch volumetric imaging.

Spider silk is considered a promising next-generation biomaterial due to its exceptional toughness, coupled with its renewability and biodegradability. Contrary to the conventional view that spider silk is mainly composed of two types of silk proteins (spidroins), MaSp1 and MaSp2, multi-omics strategies are increasingly revealing that the inclusion of complex components confers the higher mechanical properties to the material. In this review, we focus on several recent findings that report essential components and mechanisms that are necessary to reproduce the properties of natural spider silk. First, we discuss the discovery of MaSp3, a newly identified spidroin that is a major component in the composition of spider silk, in addition to the previously understood MaSp1 and MaSp2. Moreover, the role of the Spider-silk Constituting Element (SpiCE), which is present in trace amounts but has been found to significantly increase the tensile strength of artificial spider silk, is explored. We also delve into the process of spidroin fibril formation through liquid-liquid phase separation (LLPS) that forms the hierarchical structure of spider silk. In addition, we review the correlation between amino acid sequences and mechanical properties such as toughness and supercontraction, as revealed by an analysis of 1,000 spiders. In conclusion, these recent findings contribute to the comprehensive understanding of the mechanisms that give spider silk its high mechanical properties and help to improve artificial spider silk production.