Blended learning in biochemistry: The development of pre-class and post-class learning aids for electron transport chain and oxidative phosphorylation.

Electron transport chain and oxidative phosphorylation are always a challenging topic for students studying metabolism. We had adopted blended learning in metabolism teaching and evaluated the learning experiences of students. In this project, a pre-class learning aid the Story Mode and a post-class learning aid the Revision Mode in the Powerland was developed that facilitated students learning electron transport chain and oxidative phosphorylation. In the Story Mode, pathways were presented by short animations and simplified diagram that allowed students to understand basic concepts and recall simple facts of the topic. Students were asked to watch the animations before class to acquire lower level of cognitive learning first, and this facilitated students in understanding more complicated concepts later on during class. Another challenge that students faced was that they were especially weak at integrating metabolic pathways and understand the relationships between these pathways. A metro map was designed in the Revision Mode that aided students in knowledge integration, and the functions of biomolecules were summarized in flashcards that helped students in revising the concepts. This interactive self-learning tool was packaged as a courseware using the Articulate Storyline.

Using metro lines for integration of nucleotide metabolic pathways.

Students always encounter difficulties in studying biochemical pathways. They are especially weak in understanding the relationships between metabolic pathways and their integration because these pathways are always taught one-by-one in class. In the past, various online resources have been developed to facilitate students' understanding toward energy metabolism. Although these learning materials enable students to understand individual metabolic pathway in a clearer manner, many of them fail to demonstrate the linkages between these pathways. The "AG City" is a self-learning tool which aims to arouse students' interest in exploring nucleotide metabolism. We have designed a metro map as a concept map to allow students to have an overview of different pathways as well as their integration. Major pathways are presented as railway lines in an easy-to-understand and interactive manner using navigation, animations, and narrations. Key molecules involved in the pathways are presented as "railway stations". Students can easily identify common "railway stations" presented in different pathways and link the concepts that they have learnt together. This interactive self-learning tool has been packaged as a courseware using the Articulate Storyline eLearning authoring software. © 2019 International Union of Biochemistry and Molecular Biology, 47(5):532-537, 2019.

Surface-enhanced Raman scattering biosensor for DNA detection on nanoparticle island substrates.

We present a study on the surface-enhanced Raman scattering (SERS) properties of Ag nanoparticle island substrates (NIS) and their applications for target oligonucleotide (OND) detection. It has been found that the surface nanostructure of NIS samples can be controlled with a good degree of reproducibility, and a high SERS enhancement can be achieved when the peak extinction wavelength of NIS is tuned to a spectral window (approximately 60 nm) between the excitation wavelength and the scattered Raman wavelength. The highest SERS enhancement was obtained from the NIS substrates with a nominal thickness of 50 A. Detection of target OND was performed with a sandwich format in which the target OND was hybridized both to a capture OND immobilized on the NIS substrate, and a detection OND conjugated with a Raman-active dye for SERS signal generation. We compare the detection performance of two strategies based on the use of the detection OND with or without the gold nanoparticle (Au-NP). Our results confirm that, when the detection OND is coupled to the Au-NP, a better sensitivity for the target OND detection, in terms of a wider dynamic range and a lower detection limit (0.4 fM versus 1 nM without Au-NP), would be achieved.

Polyphyllin D induces mitochondrial fragmentation and acts directly on the mitochondria to induce apoptosis in drug-resistant HepG2 cells.

We previously showed that polyphyllin D (PD) produced a stronger apoptotic effect in R-HepG2 with multi-drug resistance (MDR) than that in its parent HepG2 cells without MDR. In this study, PD was found to elicit mitochondrial fragmentation in live cells by using total internal reflection fluorescence microscopy (TIRFM). When mitochondria were isolated and treated directly with PD, a stronger swelling, deeper transmembrane depolarization, and more apoptosis-inducing factor (AIF) release were observed from the mitochondria of R-HepG2 than that of HepG2. These observations suggest that PD is a potent anti-cancer agent that bypasses MDR and elicits apoptosis via mitochondrial injury.

The nuclear tubular invaginations are dynamic structures inside the nucleus of HeLa cells.

Nuclear tubules (NTs) were found in the nucleus of HeLa cells. Although no function has been ascribed to these structures, our previous data has shown that they are the sites of Ca(2+) release with mitochondria shuttled around. In the present study, we further characterized these NTs through different fluorescent dye-labeling and red fluorescent protein transfection experiments. We found that doxorubicin (Dox) is a good indicator to demonstrate the NTs since Dox is fluorescent and DNA is able to quench its fluorescence. By using confocal and electron microscopy, we show that the number and nature of the NTs in HeLa vary from cell to cell, ranging from tubular to intricately branched structures. Additionally, these NTs are double-membrane invaginations of the nuclear envelope and usually lie close to nucleolus. At rest, NTs appeared to be stable and their mouths are always closed. Upon Ca(2+) ionomycin stimulation, various forms of dynamism, including membrane protrusion to the nucleus, enlargement and shrinkage of the NTs, and distortion of the nuclear envelope and NTs were observed over a time scale of minutes. These observations suggest that the NT represents a specialized and dynamic compartment inside the nucleus under the control of Ca(2+).