How can cognitive load in visual displays of computer simulations be optimized? Middle-school chemistry students (N ϭ 257) learned with a simulation of the ideal gas law. Visual complexity was manipulated by separating the display of the simulations in 2 screens (low complexity) or presenting all information on 1 screen (high complexity). The mode of visual representation in the simulation was manipulated by presenting important information in symbolic form only (symbolic representations) or by adding iconic information to the display (iconic ϩ symbolic representations), locating the sliders controlling the simulation separated from the simulation or integrating them, and graphing either only the most recent simulation result or showing all results taken. Separated screen displays and the use of optimized visual displays each promoted comprehension and transfer, especially for low prior-knowledge learners. An expertise reversal effect was found for learners' prior general science knowledge. Results indicate that intrinsic and extraneous cognitive load in visual displays can be manipulated and that learners' prior knowledge moderates the effectiveness of these load manipulations.

This study investigated the most effective way to present an instructional video that contains words in the students' second language. Korean-speaking university students received a 16-min video lesson on Antarctica that included English narration (video + narration group), English text subtitles (video + text group), or English narration with simultaneous text subtitles (video + narration + text group). On a comprehension test, the video + text group scored higher than each of the other two groups, in contrast to the modality effect; and the video + narration + text group outscored the video + narration group, in contrast to the redundancy effect. Each of the lessons that included text was rated as less difficult than the lesson with narration only. The narration + text group reported lower effort than each of the other groups.Results highlight boundary conditions for two principles of multimedia instructional design that apply for college students who are learning in a second language. Theoretical implications are discussed. KEYWORDSimmersion education, instructional video, modality principle, multimedia learning, redundancy principle Correspondence should be sent to Hyunjeong Lee at hyunjlee@uos.ac.kr.

Placenta specific 8 (PLAC8, also known as ONZIN) is a multi-functional protein that is highly expressed in the intestine, lung, spleen, and innate immune cells, and is involved in various diseases, including cancers, obesity, and innate immune deficiency. Here, we generated a Plac8 knockout mouse using the CRISPR/Cas9 system. The Cas9 mRNA and two single guide RNAs targeting a region near the translation start codon at Plac8 exon 2 were microinjected into mouse zygotes. This successfully eliminated the conventional translation start site, as confirmed by Sanger sequencing and PCR genotyping analysis. Unlike the previous Plac8 deficient models displaying increased adipose tissue and body weights, our male Plac8 knockout mice showed rather lower body weight than sex-matched littermate controls, though the only difference between these two mouse models is genetic context. Differently from the previously constructed embryonic stem cell-derived Plac8 knockout mouse that contains a neomycin resistance cassette, this knockout mouse model is free from a negative selection marker or other external insertions, which will be useful in future studies aimed at elucidating the multi-functional and physiological roles of PLAC8 in various diseases, without interference from exogenous foreign DNA.

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