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Connexin hemichannels were identified as the first members of the eukaryotic large-pore channel family that mediate permeation of both atomic ions and small molecules between the intracellular and extracellular environments. The conventional view is that their pore is a large passive conduit through which both ions and molecules diffuse in a similar manner. In stark contrast to this notion, we demonstrate that the permeation of ions and of molecules in connexin hemichannels can be uncoupled and differentially regulated. We find that human connexin mutations that produce pathologies and were previously thought to be loss-of-function mutations due to the lack of ionic currents are still capable of mediating the passive transport of molecules with kinetics close to those of wild-type channels. This molecular transport displays saturability in the micromolar range, selectivity, and competitive inhibition, properties that are tuned by specific interactions between the permeating molecules and the N-terminal domain that lies within the pore-a general feature of large-pore channels. We propose that connexin hemichannels and, likely, other large-pore channels, are hybrid channel/transporter-like proteins that might switch between these two modes to promote selective ion conduction or autocrine/paracrine molecular signaling in health and disease processes.

Abstract A major driver of neuronal hyperexcitability is dysfunction of K+ channels, including voltage-gated KCNQ2/3 channels. Their hyperpolarized midpoint of activation and slow activation and deactivation kinetics produce a current that regulates membrane potential and impedes repetitive firing. Inherited mutations in KCNQ2 and KCNQ3 are linked to a wide spectrum of neurodevelopmental disorders (NDDs), ranging from benign familial neonatal seizures to severe epileptic encephalopathies and autism spectrum disorders. However, the impact of these variants on the molecular mechanisms underlying KCNQ3 channel function remains poorly understood and existing treatments have significant side effects. Here, we use voltage clamp fluorometry, molecular dynamic simulations, and electrophysiology to investigate NDD-associated variants in KCNQ3 channels. We identified two distinctive mechanisms by which loss– and gain–of function NDD-associated mutations in KCNQ3 affect channel gating: one directly affects S4 movement while the other changes S4-to-pore coupling. MD simulations and electrophysiology revealed that polyunsaturated fatty acids (PUFAs) primarily target the voltage-sensing domain in its activated conformation and form a weaker interaction with the channel’s pore. Consistently, two such compounds yielded partial and complete functional restoration in R227Q- and R236C-containing channels, respectively. Our results reveal the potential of PUFAs to be developed into therapies for diverse KCNQ3-based channelopathies.

Learner control of video presentations by using pause buttons or timeline scrollbars was suggested as helpful for learning from sources of transient information such as dynamic visualizations and spoken words. However, effective learner control could be difficult to attain without sufficient instructional support. This study developed strategies for facilitating processing and integration of transient information based on cognitive load theory by providing learners with explicit guidance in when and how to use pausing and timeline scrollbars while watching instructional videos. A single-factor between-subjects experiment was conducted to examine the effects of the proposed strategies. Ninety undergraduates were randomly assigned to one of three groups - strategy guidance group (learners were provided with guidance in strategies), learner control group (learners were allowed to control the video but without any guidance in strategies), and continuous presentation group (without any learner control mechanism). The results revealed that compared to the learner control group, the strategy guidance group had a greater number of pauses and scrollbacks on the timeline, demonstrated significantly better performance in the immediate comprehension test and higher performance efficiency in the immediate recall and comprehension tests. Compared to the continuous presentation group, the strategy guidance group demonstrated significantly better performance in the immediate recall and comprehension tests and higher performance efficiency in both these tests, as well as better performance in the delayed recall test and higher performance efficiency in the delayed recall test.

The connexin family is a diverse group of highly regulated wide-pore channels permeable to biological signaling molecules. Despite the critical roles of connexins in mediating selective molecular signaling in health and disease, the basis of molecular permeation through these pores remains unclear. Here, we report the thermodynamics and kinetics of binding and transport of a second messenger, adenosine-3',5'-cyclophosphate (cAMP), through a connexin26 hemichannel (Cx26). First, inward and outward fluxes of cAMP molecules solvated in KCl solution were obtained from 4 μs of ± 200 mV simulations. These fluxes data yielded a single-channel permeability of cAMP and cAMP/K+ permeability ratio consistent with experimentally measured values. The results from voltage simulations were then compared with the potential of mean force (PMF) and the mean first passage times (MFPTs) of a single cAMP without voltage, obtained from a total of 16.5 μs of Voronoi-tessellated Markovian milestoning simulations. Both the voltage simulations and the milestoning simulations revealed two cAMP-binding sites, for which the binding constants KD and dissociation rates koff were computed from PMF and MFPTs. The protein dipole inside the pore produces an asymmetric PMF, reflected in unequal cAMP MFPTs in each direction once within the pore. The free energy profiles under opposite voltages were derived from the milestoning PMF and revealed the interplay between voltage and channel polarity on the total free energy. In addition, we show how these factors influence the cAMP dipole vector during permeation, and how cAMP affects the local and nonlocal pore diameter in a position-dependent manner.

We investigated whether the temporal contiguity effect, which holds that information sources, such as visual information and narration need to be temporally coordinated for learning to be effective, can also be found in narrated slideshows. A concurrent presentation-key point format (CPK), in which visual information sequentially appeared as key points on the slide with corresponding narration, was compared to a concurrent presentation-whole format (CPW), in which visual information was shown all at once on the slide with corresponding narration, and a sequential presentation format (SP), in which the narration was played first before all the corresponding visual information was presented at once. Ninety-nine undergraduates were randomly divided across the CPK, CPW and SP conditions. Results revealed that participants in the CPK group had higher post-test performance and learning efficiency than participants in the CPW and SP conditions. Performance in the CPW condition was higher than in the SP conditions, but only in terms of learning efficiency. The results suggested that the occurrence of the temporal contiguity effect not only depends on whether the presentation of narration and visual information in narrated slideshows is concurrent or not, but also on how concurrent it is.

System pausing at pre-determined positions during multimedia presentations can enhance multimedia learning. However, the pause positions are usually set up based on the structure of the learning material (e.g., segmentation principle) rather than on the complexity of its different sections (as determined by levels of element interactivity, according to cognitive load theory). This study investigated the effectiveness of complexity-determined system pauses positioned either before or after complex (high element interactivity) sections of a slideshow multimedia presentation. The study adopted a single-factor between-subjects design and randomly assigned 128 undergraduates to four experimental conditions, namely (1) pausing before high element interactivity, (2) pausing after high element interactivity, (3) learner pausing and (4) no pausing. The research results revealed that complexity-determined system pausing approaches and learner pausing resulted in better test performance and instructional efficiency than the continuous presentation without pausing. The findings suggest that pauses allow students more time to deal with learning contents with high element interactivity, thus reducing potential cognitive overload and resulting in better performance compared with continuous presentation. However, no significant difference was found between the two types of system pausing and learner pausing in all measures.

Redundancy effect has been investigated in many controlled experimental studies, however, it is seldom investigated whether the same redundant material may cause different results in classroom, which is a major learning place for students. Considering that it is not easy to control the internal validity in classroom environment, this study proposed a new research approach with the use of virtual reality (VR) classroom as the experimental platform to investigate this issue. In the current study, one hundred and four fifth-grade students were randomly assigned to four experimental conditions with two different presentation formats (redundant and non-redundant) and two learning environments (lab and VR classroom). The retention test scores, cognitive load, and performance efficiency were used as dependent variables. The results revealed that the redundancy effect occurred in the lab environment and the reverse redundancy effect occurred in the VR classroom environment. In the lab environment, participants who had learned with non-redundant materials demonstrated better learning performance than those who had learned with redundant materials. On the contrary, the results were reversed in the VR classroom environment. The programmed interferences in the VR classroom are suggested as the main factor influencing the results.

Although a modality effect indicating better learning from an animation with spoken learning guidance than from an animation with written learning guidance has often been found in research on learning from animation, the effect has hardly been investigated for learning from computer simulation. This study examined the interaction effects between the multimedia types of animation and computer simulation, and the presentation modes of written and spoken learning guidance. Based on cognitive load theory and the specific characteristics of the multimedia types it was hypothesized that a modality effect would be replicated in the animation condition and a reverse modality effect would be found in the simulation condition. Results partially supported the hypotheses, indicating that participants learned more from animation when it was accompanied with spoken text, and from a simulation when it was accompanied with written text. However, no effect was found for cognitive load. Based on the results, spoken text is recommended to be used to guide learners in animations assisted learning environments, and written text is recommended to be used to guide learners in simulations assisted learning environments.

Taiwan's bed and breakfast (B&B) industry has experienced significant development in its nearly 25-year history, transforming from B&B run by retirees to mature service providers that adopt modern business and Internet technology skills in line with sustainable lodging development. This study explores the basic professional capabilities required for the sustainable development of B&B management, including social-emotional intelligence (EQ) capabilities and their impact on the quality of sustainable tourism services. The study used the K–S Z test to assess the importance of various abilities, including emotional intelligence abilities, financial management abilities, technical skills abilities and marketing abilities. The findings, validated with p-values less than 0.05, confirm the multi-disciplinary nature of sustainable tourism management skills in B&Bs and highlight their importance in sustainable service attitudes and strategic marketing. The identified capabilities are not only crucial for the sustainable development of the B&B industry, but are also crucial for contributing to the B&B's national diplomacy and sustainable development status in global tourism. This study provides both novice and experienced B&B operators with actionable insights to improve their operational efficiency and achieve sustainable tourism development goals. [ABSTRACT FROM AUTHOR]

Amyloid-beta peptide (Aβ) is a neurotoxic constituent of senile plaques in the brains of Alzheimer's disease (AD) patients. The detailed mechanisms by which protein kinase C-delta (PKCδ) contributes to Aβ toxicity is not yet entirely understood. Using fully differentiated primary rat cortical neurons, we found that inhibition of Aβ25-35-induced PKCδ increased cell viability with restoration of neuronal morphology. Using cyclin D1, proliferating cell nuclear antigen (PCNA), and histone H3 phosphorylated at Ser-10 (p-Histone H3) as the respective markers for the G1-, S-, and G2/M-phases, PKCδ inhibition mitigated cell cycle reentry (CCR) and subsequent caspase-3 cleavage induced by both Aβ25-35 and Aβ1-42 in the post-mitotic cortical neurons. Upstream of PKCδ, signal transducers and activators of transcription (STAT)-3 mediated PKCδ induction, CCR, and caspase-3 cleavage upon Aβ exposure. Downstream of PKCδ, aberrant neuronal CCR was triggered by overactivating cyclin-dependent kinase-5 (CDK5) via calpain2-dependent p35 cleavage into p25. Finally, PKCδ and CDK5 also contributed to Aβ25-35 induction of p53-upregulated modulator of apoptosis (PUMA) in cortical neurons. Together, we demonstrated that, in the post-mitotic neurons exposed to Aβs, STAT3-dependent PKCδ expression triggers calpain2-mediated p35 cleavage into p25 to overactivate CDK5, thus leading to aberrant CCR, PUMA induction, caspase-3 cleavage, and ultimately apoptosis. [ABSTRACT FROM AUTHOR]