Transitions of protein traffic from cardiac ER to junctional SR

The junctional sarcoplasmic reticulum (jSR) is an important and unique ER subdomain in the adult myocyte that concentrates resident proteins to regulate Ca(2+) release. To investigate cellular mechanisms for sorting and trafficking proteins to jSR, we overexpressed canine forms of junctin (JCT) or triadin (TRD) in adult rat cardiomyocytes. Protein accumulation over time was visualized by confocal fluorescence microscopy using species-specific antibodies. Newly synthesized JCTdog and TRDdog appeared by 12-24h as bright fluorescent puncta close to the nuclear surface, decreasing in intensity with increasing radial distance. With increasing time (24-48h), fluorescent puncta appeared at further radial distances from the nuclear surface, eventually populating jSR similar to steady-state patterns. CSQ2-DsRed, a form of CSQ that polymerizes ectopically in rough ER, prevented anterograde traffic of newly made TRDdog and JCTdog, demonstrating common pathways of intracellular trafficking as well as in situ binding to CSQ2 in juxtanuclear rough ER. Reversal of CSQ-DsRed interactions occurred when a form of TRDdog was used in which CSQ2-binding sites are removed ((del)TRD). With increasing levels of expression, CSQ2-DsRed revealed a novel smooth ER network that surrounds nuclei and connects the nuclear axis. TRDdog was retained in smooth ER by binding to CSQ2-DsRed, but escaped to populate jSR puncta. TRDdog and (del)TRD were therefore able to elucidate areas of ER-SR transition. High levels of CSQ2-DsRed in the ER led to loss of jSR puncta labeling, suggesting a plasticity of ER-SR transition sites. We propose a model of ER and SR protein traffic along microtubules, with prominent transverse/radial ER trafficking of JCT and TRD along Z-lines to populate jSR, and an abundant longitudinal/axial smooth ER between and encircling myonuclei, from which jSR proteins traffic

Use of High-Definition Audiovisual Technology in a Gross Anatomy Laboratory: Effect on Dental Students\u27 Learning Outcomes and Satisfaction

Laboratory cadaver dissection is essential for three-dimensional understanding of anatomical structures and variability, but there are many challenges to teaching gross anatomy in medical and dental schools, including alack of available space and qualified anatomy faculty. The aim of this study was to determine the efficacy of high-definition audiovisual educational technology in the gross anatomy laboratory in improving dental students\u27 learning outcomes and satisfaction. Exam scores were compared for two classes of first-year students at one U.S. dental school: 2012-13 (no audiovisual technology) and 2013-14 (audiovisual technology), and section exams were used to compare differences between semesters. Additionally, an online survey was used to assess the satisfaction of students who used the technology. All 284 first-year students in the two years (2012-13 N=144; 2013-14 N=140) participated in the exams. Of the 140 students in the 2013-14 class, 63 completed the survey (45% response rate). The results showed that those students who used the technology had higher scores on the laboratory exams than those who did not use it, and students in the winter semester scored higher (90.17 +/- 0.56) than in the fall semester (82.10 +/- 0.68). More than 87% of those surveyed strongly agreed or agreed that the audiovisual devices represented anatomical structures clearly in the gross anatomy laboratory. These students reported an improved experience in learning and understanding anatomical structures, found the laboratory to be less overwhelming, and said they were better able to follow dissection instructions and understand details of anatomical structures with the new technology. Based on these results, the study concluded that the ability to provide the students a clear view of anatomical structures and high-quality imaging had improved their learning experience