Exocyst complex component 2 is a potential host factor for SARS-CoV-2 infection

iPS細胞やオルガノイド技術を用いた新型コロナウイルス感染におけるEXOC2の機能解析. 京都大学プレスリリース. 2022-10-27.An important host factor in SARS-CoV-2 infection, identified using iPS cell and organoid technology. 京都大学プレスリリース. 2022-10-31.Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused an epidemic and spread rapidly all over the world. Because the analysis of host factors other than receptors and proteases has not been sufficiently performed, we attempted to identify and characterize host factors essential for SARS-CoV-2 infection using iPS cells and airway organoids (AO). Based on previous CRISPR screening and RNA-seq data, we found that exocyst complex component 2 (EXOC2) is one important host factor for SARS-CoV-2 infection. The intracellular SARS-CoV-2 nucleocapsid (N) expression level was decreased to 3.7 % and the virus copy number in cell culture medium was decreased to 1.6 % by EXOC2 knockdown. Consistently, immunostaining results showed that N protein-positive cells were significantly decreased by EXOC2 knockdown. We also found that EXOC2 knockdown downregulates SARS-CoV-2 infection by regulating IFNW1 expression. In conclusion, controlling the EXOC2 expression level may prevent SARS-CoV-2 infection and deserves further study

Control of seed formation allows two distinct self-sorting patterns of supramolecular nanofibers

自己組織化する分子繊維のネットワークを種形成の制御で作り分けることに成功 --人工スマートマテリアル設計の新機軸として期待--. 京都大学プレスリリース. 2020-08-26.Self-sorting double network hydrogels comprising orthogonal supramolecular nanofibers have attracted attention as artificially-regulated multi-component systems. Regulation of network patterns of self-sorted nanofibers is considered as a key for potential applications such as optoelectronics, but still challenging owing to a lack of useful methods to prepare and analyze the network patterns. Herein, we describe the selective construction of two distinct self-sorting network patterns, interpenetrated and parallel, by controlling the kinetics of seed formation with dynamic covalent oxime chemistry. Confocal imaging reveals the interpenetrated self-sorting network was formed upon addition of O-benzylhydroxylamine to a benzaldehyde-tethered peptide-type hydrogelator in the presence of lipid-type nanofibers. We also succeed in construction of a parallel self-sorting network through deceleration of seed formation using a slow oxime exchange reaction. Through careful observation, the formation of peptide-type seeds and nanofibers is shown to predominantly occur on the surface of the lipid-type nanofibers via highly dynamic and thermally-fluctuated processes

Spread of Risk Information Through Microblogs: Twitter Users with More Mutual Connections Relay News That is More Dreadful

In elucidating the spread of risk information through microblogging, it is important to understand the behaviors of numerous average users, in addition to the activities of authorities. We followed the transmission pathways of 10 actual widely spread tweets concerning several risk information topics, including natural disasters, nuclear disasters, and infectious diseases, and we identified the types of risk that affected retweeting by classifying each tweet based on Slovic’s risk perception model. Furthermore, we examined the types of users who did and did not retweet the information. Users with few connections in the form of followers (i.e., people who are following a user) or followees (people a user is following), or with a low ratio of mutual followers within their connections, had a tendency to retweet a large amount of risk information, regardless of the type of risk involved. On the other hand, users with a high ratio of mutual followers exhibited a greater tendency to retweet risk information when it was perceived as dreadful, though they did not retweet risk information much on the whole. These results suggest that there are two mechanisms by which risk information is spread within the Twitter network: information exchange and social sharing of personal reactions

Cord blood BPA and reproductive and thyroid hormone levels of neonates

Background: Bisphenol A (BPA) is widely used and BPA exposure is nearly ubiquitous in developed countries. While animal studies have indicated adverse health effects of prenatal BPA exposure including reproductive dysfunction and thyroid function disruption possibly in sex-specific manner, findings from epidemiological studies have not been enough to proof these adverse effects. Given very limited research on human, the aim of this study was to investigate associations between cord blood BPA levels and reproductive and thyroid hormone levels of neonates and whether associations differed by neonate sex. Methods: Among 514 participants of the Hokkaido study who were recruited from 2002 to 2005 at one hospital in Sapporo, Japan. BPA level in cord blood was determined by ID-LC/MS/MS and the limit of quantification was 0.040 ng/ml. 9 types of reproductive hormone levels in cord blood were measured and thyroid hormone levels were obtained from neonate mass screening test data. 283 subjects those who had both BPA and hormone levels measurements were included for the final analyses. Results: Geometric mean of cord blood BPA was 0.051 ng/ml. After adjustment, BPA level was negatively associated with prolactin (PRL) (β=-0.38). There was an interaction between infant sex and BPA levels on PRL, weak negative association was found in boys (β=-0.12) whereas weak positive association was found in girls (β=0.14). BPA level showed weak positive association with testosterone, estradiol and progesterone levels in boys. No association was found between BPA and thyroid hormone levels. Conclusions: Our findings suggested that fetal BPA levels might be associated with certain reproductive hormone levels of neonate with sex-specific manner, though further investigations are necessary

Universal Single-Mode Lasing in Fully Chaotic Billiard Lasers

By numerical simulations and experiments of fully chaotic billiard lasers, we show that single-mode lasing states are stable, whereas multi-mode lasing states are unstable when the size of the billiard is much larger than the wavelength and the external pumping power is sufficiently large. On the other hand, for integrable billiard lasers, it is shown that multi-mode lasing states are stable, whereas single-mode lasing states are unstable. These phenomena arise from the combination of two different nonlinear effects of mode-interaction due to the active lasing medium and deformation of the billiard shape. Investigations of billiard lasers with various shapes revealed that single-mode lasing is a universal phenomenon for fully chaotic billiard lasers

Visualization of complex DNA double-strand breaks in a tumor treated with carbon ion radiotherapy.

Carbon ion radiotherapy shows great potential as a cure for X-ray-resistant tumors. Basic research suggests that the strong cell-killing effect induced by carbon ions is based on their ability to cause complex DNA double-strand breaks (DSBs). However, evidence supporting the formation of complex DSBs in actual patients is lacking. Here, we used advanced high-resolution microscopy with deconvolution to show that complex DSBs are formed in a human tumor clinically treated with carbon ion radiotherapy, but not in a tumor treated with X-ray radiotherapy. Furthermore, analysis using a physics model suggested that the complexity of radiotherapy-induced DSBs is related to linear energy transfer, which is much higher for carbon ion beams than for X-rays. Visualization of complex DSBs in clinical specimens will help us to understand the anti-tumor effects of carbon ion radiotherapy