Rho-GTPase–dependent filamentous actin dynamics coordinate vesicle targeting and exocytosis during tip growth

The dynamic activity of tip-localized filamentous actin (F-actin) in pollen tubes is controlled by counteracting RIC4 and RIC3 pathways downstream of the ROP1 guanosine triphosphatase promoting actin assembly and disassembly, respectively. We show here that ROP1 activation is required for both the polar accumulation and the exocytosis of vesicles at the plasma membrane apex. The apical accumulation of exocytic vesicles oscillated in phase with, but slightly behind, apical actin assembly and was enhanced by overexpression of RIC4. However, RIC4 overexpression inhibited exocytosis, and this inhibition could be suppressed by latrunculin B treatment or RIC3 overexpression. We conclude that RIC4-dependent actin assembly is required for polar vesicle accumulation, whereas RIC3-mediated actin disassembly is required for exocytosis. Thus ROP1-dependent F-actin dynamics control tip growth through spatiotemporal coordination of vesicle targeting and exocytosis

Implementing Synchronous Online Flipped Learning for Pre-service Teachers During COVID-19

Most research has examined flipped learning within the context of face-to-face (F2F) instruction. However, previous research has not effectively explored the possibility of how online synchronous flipped learning influences pre-service teachers (PSTs) in teacher education programs during Coronavirus disease (COVID-19). Recognizing the gap in the literature, this paper explored three aspects of online synchronous flipped learning by understanding 1) PSTs' learner engagement, 2) self-directed learning, and 3) learner satisfaction in a Korean university. The data was collected from Korean PST's interviews, reflection notes, and course evaluations. The thematic analysis was used to analyze qualitative data sources. The study findings showed that PSTs favored a synchronous online FL because it encouraged them to engage in various collaborative activities through Zoom breakout sessions. Also, pre-class materials from online FL can positively enhance the PSTs' self-directed learning process. Based on these findings, this study provides suggestions on how to effectively implement online synchronous flipped learning in teacher education programs

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Summary Rapid tip growth allows for efficient development of highly elongated cells (e.g. neuronal axons, fungal hyphae and pollen tubes) and requires an elaborate spatiotemporal regulation of the growing region. Here, we use the pollen tube as a model to investigate the mechanism regulating the growing region. ROPs (Rho-related GTPases from plants) are essential for pollen tip growth and display oscillatory activity changes in the apical plasma membrane (PM). By manipulating the ROP activity level, we showed that the PM distribution of ROP activity as an apical cap determines the tip growth region and that efficient tip growth requires an optimum level of the apical ROP1 activity. Excessive ROP activation induced the enlargement of the tip growth region, causing growth depolarization and reduced tube elongation. Time-lapse analysis suggests that the apical ROP1 cap is generated by lateral propagation of a localized ROP activity. Subcellular localization and gain-and loss-of-function analyses suggest that RhoGDI-and RhoGAP-mediated global inhibition limits the lateral propagation of apical ROP1 activity. We propose that the balance between the lateral propagation and the global inhibition maintains an optimal apical ROP1 cap and generates the apical ROP1 activity oscillation required for efficient pollentube elongation

International Students' Experiences of Content Language Integrated Learning in a Korean University: Focusing on Korean as a Medium of Instruction

This study explores international graduate students' experiences of content-language integrated learning (CLIL) at a university in Korea. This study focuses on a course that allows international students to simultaneously learn the Korean language and content knowledge. Korean as a medium of instruction (KMI) was applied to 16 international graduate students in two graduate courses during the 2021 Fall semester. The survey examines the perception and satisfaction of students' experiences in the KMI classes. Among survey participants, interview applicants were selected for in-depth interviews. Study results showed that international graduate students developed content knowledge through KMI classes. They also improved their Korean language ability. Overall, international students were generally satisfied with KMI classes. However, it is difficult for international students to dramatically enhance their Korean academic proficiency within one semester. Recommendations are provided on effectively conducting CLIL classes, such as KMI for international students in higher education

Korean Pre-service Teachers' Flipped Learning Experiences in a Teacher Education Program

This study explores Korean pre-service teachers' perceptions, attitudes, and satisfaction with flipped learning courses in a teacher education program. A mixed research method was used to collect the end-of-semester survey (n=62) and individual interview data (n=4). Guided by the four pillars of flipped learning (FL), study results are followed. First, Korean pre-service teachers believed that flipped learning format provided a flexible learning environment where pre-service teachers (PSTs) learn course materials in their own space. This result indicated that their learning happened without the limits of time and space. Second, pre-service teachers showed that their self-directed learning could be enhanced while watching pre-recorded videos before attending the class. Most PSTs agreed that their self-directed learning could be enhanced after participating in the flipped learning courses. Third, pre-service teachers evaluated that the FL course instructor was a professional educator who conveyed the intentional content effectively. Fourth, pre-service teachers were generally satisfied with the FL courses and were willing to take the FL courses again in the future

Sub-sampled dictionaries for coarse-to-fine sparse representation-based human action recognition

Automatic human action recognition is a core functionality of systems for video surveillance and human-object interaction. However, the diverse nature of human actions and the noisy nature of most video content make it difficult to achieve effective human action recognition. To overcome the aforementioned problems, Sparse Representation (SR) has recently attracted substantial research attention. However, although SR-based approaches have proven to be reasonably effective, the computational complexity of the testing stage prohibits their usage by applications requiring support for real-time operation and a vast number of human action classes. In this paper, we propose a novel method for human action recognition, leveraging coarse-to-fine sparse representations that have been obtained through dictionary sub-sampling. Comparative experimental results obtained for the UCF50 dataset demonstrate that the proposed method is able to achieve efficient human action recognition, at no substantial loss in recognition accuracy