Pexophagy suppresses ROS-induced damage in leaf cells under high-intensity light

Although light is essential for photosynthesis, it has the potential to elevate intracellular levels of reactive oxygen species (ROS). Since high ROS levels are cytotoxic, plants must alleviate such damage. However, the cellular mechanism underlying ROS-induced leaf damage alleviation in peroxisomes was not fully explored. Here, we show that autophagy plays a pivotal role in the selective removal of ROS-generating peroxisomes, which protects plants from oxidative damage during photosynthesis. We present evidence that autophagy-deficient mutants show light intensity-dependent leaf damage and excess aggregation of ROS-accumulating peroxisomes. The peroxisome aggregates are specifically engulfed by pre-autophagosomal structures and vacuolar membranes in both leaf cells and isolated vacuoles, but they are not degraded in mutants. ATG18a-GFP and GFP-2×FYVE, which bind to phosphatidylinositol 3-phosphate, preferentially target the peroxisomal membranes and pre-autophagosomal structures near peroxisomes in ROS-accumulating cells under high-intensity light. Our findings provide deeper insights into the plant stress response caused by light irradiation

The Prdgnanz tendency in 3-dimensional patterns

This paper examines the Pragnanz tendency in 3-dimensional patterns in relation to the tendency to convexity. Past studies on Pragnanz have been carried out mainly with exemplification of 2-dimensional configurations. It would seem worth studying how the Pragnanz tendency would emerge in the case of 3-dimensional patterns and whether the tendency to convexity would also prevail. Two convex-concave patterns were used in this study, and the observers\u27 reports were collected on how the patterns were perceived, with monocular and binocular views. On both the patterns, monocular views led to the perception of uniform patterns instead of the convex-concave configurations, while binocular views sometimes led to the veridical perception. In conclusion, the Pragnanz tendency was recognized in 3-dimensional patterns. The tendency to convexity was also observed

基本6表情認知における注視部位の基礎的検討 : FACSに基づいた日本人表情刺激を用いて

The observer\u27s fixation points and time spent for recognizing six basic expressions (happiness, sadness, anger, disgust, fear, and surprise) were examined, using the Japanese facial expressions composed based on the FACS (Facial Action Coding System). The fixation points were measured by means of the Eye-tracker for 11 undergraduate students and 3 graduate students of a women\u27s university. The results showed that the longest fixation time required was at the points of eyes in all six facial expressions. Moreover, longer fixation time spent was recorded (1) at the points of a mouth in the disgust expression ; (2) at the points of a nose in the fear ; (3) at the points of eyebrows in the anger and the sadness

基本6表情認知における注視部位の基礎的検討 II : 刺激提示前の注視点の位置がカテゴリー判断に及ぼす影響

For the recognition of six basic expressions (happiness, surprise, fear, sadness, anger and disgust) using, as the stimulus, Japanese facial expression images composed on the basis of the FACS (Facial Action Coding System), the time spent by the observer was measured for scanning each facial area (forehead, brow, eye, nose, mouth and cheek) of the stimulus. In Bamba and Uemura (2007), the visual fixation point seen by the observer preceding the presentation of each stimulus was located in the area corresponding to the middle of the two eyes of the stimulus. In the present study, we examined the observer\u27s fixation under four different conditions for the prefixation point, viz. corresponding to the upper, lower, left and right positions of the subsequent stimulus. The fixation time was measured by means of an Eye-tracker. Twenty undergraduate and graduate students of a women\u27s university participated as the observers. The results showed that the longest fixation time required was in the eye area in all the six facial expressions, regardless of the location of the pre-fixation point

TMPRSS11D and TMPRSS13 Activate the SARS-CoV-2 Spike Protein

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) utilizes host proteases, including a plasma membrane-associated transmembrane protease, serine 2 (TMPRSS2) to cleave and activate the virus spike protein to facilitate cellular entry. Although TMPRSS2 is a well-characterized type II transmembrane serine protease (TTSP), the role of other TTSPs on the replication of SARS-CoV-2 remains to be elucidated. Here, we have screened 12 TTSPs using human angiotensin-converting enzyme 2-expressing HEK293T (293T-ACE2) cells and Vero E6 cells and demonstrated that exogenous expression of TMPRSS11D and TMPRSS13 enhanced cellular uptake and subsequent replication of SARS-CoV-2. In addition, SARS-CoV-1 and SARS-CoV-2 share the same TTSPs in the viral entry process. Our study demonstrates the impact of host TTSPs on infection of SARS-CoV-2, which may have implications for cell and tissue tropism, for pathogenicity, and potentially for vaccine development

SARS-CoV-2 variants with mutations at the S1/S2 cleavage site are generated in vitro during propagation in TMPRSS2-deficient cells

The spike (S) protein of Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2) binds to a host cell receptor which facilitates viral entry. A polybasic motif detected at the cleavage site of the S protein has been shown to broaden the cell tropism and transmissibility of the virus. Here we examine the properties of SARS-CoV-2 variants with mutations at the S protein cleavage site that undergo inefficient proteolytic cleavage. Virus variants with S gene mutations generated smaller plaques and exhibited a more limited range of cell tropism compared to the wild-type strain. These alterations were shown to result from their inability to utilize the entry pathway involving direct fusion mediated by the host type II transmembrane serine protease, TMPRSS2. Notably, viruses with S gene mutations emerged rapidly and became the dominant SARS-CoV-2 variants in TMPRSS2-deficient cells including Vero cells. Our study demonstrated that the S protein polybasic cleavage motif is a critical factor underlying SARS-CoV-2 entry and cell tropism. As such, researchers should be alert to the possibility of de novo S gene mutations emerging in tissue-culture propagated virus strains