Nerve-independent formation of a topologically complex postsynaptic apparatus

As the mammalian neuromuscular junction matures, its acetylcholine receptor (AChR)–rich postsynaptic apparatus is transformed from an oval plaque into a pretzel-shaped array of branches that precisely mirrors the branching pattern of the motor nerve terminal. Although the nerve has been believed to direct postsynaptic maturation, we report here that myotubes cultured aneurally on matrix-coated substrates form elaborately branched AChR-rich domains remarkably similar to those seen in vivo. These domains share several characteristics with the mature postsynaptic apparatus, including colocalization of multiple postsynaptic markers, clustering of subjacent myonuclei, and dependence on the muscle-specific kinase and rapsyn for their formation. Time-lapse imaging showed that branched structures arise from plaques by formation and fusion of AChR-poor perforations through a series of steps mirroring that seen in vivo. Multiple fluorophore imaging showed that growth occurs by circumferential, asymmetric addition of AChRs. Analysis in vivo revealed similar patterns of AChR addition during normal development. These results reveal the sequence of steps by which a topologically complex domain forms on a cell and suggest an unexpected nerve-independent role for the postsynaptic cell in generating this topological complexity

A Comparative Analysis Of Computer-Assisted Instruction And Traditional Lecture Instruction For Administration And Management Topics In Physical Therapy Education

Technological advancements and competition in student recruitment have challenged educational institutions to expand upon traditional teaching methods in order to attract, engage and retain students.  One strategy to meet this shift from educator-directed teaching to student-centered learning is greater computer utilization as an integral aspect of the learning environment. The purpose of the present study was to assess the effectiveness of utilizing Computer-Assisted Instruction (CAI) to teach administration and management content in Physical Therapy (PT) education. It was hypothesized that CAI is equally effective for assimilation of information when compared to traditional lecture instruction (TLI).  The sample consisted of third-year entry-level PT students enrolled in an Administration and Management course.  Thirty-three of forty students who met the inclusion criteria consented to participate.  Both the Mercy College and Seton Hall University IRB boards approved the project and all students signed informed consents.  Participants were randomly assigned to the control (TLI, n=16) or experimental (CAI, n=17) group. Each participant completed a pretest on the material to be covered and a demographic survey to assess grade point average (GPA), gender, age and computer literacy. Students then attended the course in the designated medium and took a post-test at the end of the semester.  There were no significant differences between the two groups for GPA, age or gender. Both groups showed significant improvement from pretest to post-test (51.5±12.7 to 80.6±7.8; p<0.001), and (52.0±9.5 to 85.1±6.1; p<0.001), respectively. No significant difference was found between the groups for baseline knowledge (52.0±9.5 vs. 51.5±12.7; p=0.905), final exam scores (80.6±7.8 vs. 85.1±6.1; p=0.073) or final course grades (90.2±3.0 vs. 90.5±3.1; p=0.763).  The hypotheses that CAI is equally effective for assimilation and retention of information presented in a professional management and administration PT class, when compared to TLI, was supported. Areas for further analysis include examining student satisfaction levels, work efficiency and long-term retention of material.  With both teaching methods found to be equally effective, educators can utilize CAI to promote a student-centered experience for the high tech learners of today.  Hiring faculty from remote locations to fill positions for which candidates are unavailable locally, and allowing instructors to teach multiple sections of the same course at different geographic campuses, is also possible with CAI. Additionally, if the instructor or student is absent or a lecture is not finished in the classroom, the material can be placed online. This new evidence supports the use of CAI in teaching administration and management material to PT students, providing institutions of higher learning with an alternative teaching strategy to meet the needs of today’s students

Improved Tools for the Brainbow Toolbox

In the transgenic multicolor labeling strategy called 'Brainbow', Cre-loxP recombination is used to create a stochastic choice of expression among fluorescent proteins, resulting in the indelible marking of mouse neurons with multiple distinct colors. This method has been adapted to non-neuronal cells in mice and to neurons in fish and flies, but its full potential has yet to be realized in the mouse brain. Here we present several lines of mice that overcome limitations of the initial lines, and we report an adaptation of the method for use in adeno-associated viral vectors. We also provide technical advice about how best to image Brainbow-expressing tissue.Molecular and Cellular Biolog

Agrin and Synaptic Laminin Are Required to Maintain Adult Neuromuscular Junctions

As synapses form and mature the synaptic partners produce organizing molecules that regulate each other’s differentiation and ensure precise apposition of pre- and post-synaptic specializations. At the skeletal neuromuscular junction (NMJ), these molecules include agrin, a nerve-derived organizer of postsynaptic differentiation, and synaptic laminins, muscle-derived organizers of presynaptic differentiation. Both become concentrated in the synaptic cleft as the NMJ develops and are retained in adulthood. Here, we used mutant mice to ask whether these organizers are also required for synaptic maintenance. Deletion of agrin from a subset of adult motor neurons resulted in the loss of acetylcholine receptors and other components of the postsynaptic apparatus and synaptic cleft. Nerve terminals also atrophied and eventually withdrew from muscle fibers. On the other hand, mice lacking the presynaptic organizer laminin-α4 retained most of the synaptic cleft components but exhibited synaptic alterations reminiscent of those observed in aged animals. Although we detected no marked decrease in laminin or agrin levels at aged NMJs, we observed alterations in the distribution and organization of these synaptic cleft components suggesting that such changes could contribute to age-related synaptic disassembly. Together, these results demonstrate that pre- and post-synaptic organizers actively function to maintain the structure and function of adult NMJs.Molecular and Cellular Biolog

Tyrosine-phosphorylated and nonphosphorylated isoforms of α-dystrobrevin: roles in skeletal muscle and its neuromuscular and myotendinous junctions

α-Dystrobrevin (DB), a cytoplasmic component of the dystrophin–glycoprotein complex, is found throughout the sarcolemma of muscle cells. Mice lacking αDB exhibit muscular dystrophy, defects in maturation of neuromuscular junctions (NMJs) and, as shown here, abnormal myotendinous junctions (MTJs). In normal muscle, alternative splicing produces two main αDB isoforms, αDB1 and αDB2, with common NH2-terminal but distinct COOH-terminal domains. αDB1, whose COOH-terminal extension can be tyrosine phosphorylated, is concentrated at the NMJs and MTJs. αDB2, which is not tyrosine phosphorylated, is the predominant isoform in extrajunctional regions, and is also present at NMJs and MTJs. Transgenic expression of either isoform in αDB−/− mice prevented muscle fiber degeneration; however, only αDB1 completely corrected defects at the NMJs (abnormal acetylcholine receptor patterning, rapid turnover, and low density) and MTJs (shortened junctional folds). Site-directed mutagenesis revealed that the effectiveness of αDB1 in stabilizing the NMJ depends in part on its ability to serve as a tyrosine kinase substrate. Thus, αDB1 phosphorylation may be a key regulatory point for synaptic remodeling. More generally, αDB may play multiple roles in muscle by means of differential distribution of isoforms with distinct signaling or structural properties

NEW TOOLS FOR THE BRAINBOW TOOLBOX

In a recently introduced transgenic multicolor labeling strategy called “Brainbow,” Cre-lox recombination is used to create a stochastic choice of expression among fluorescent proteins (XFPs), resulting in the indelible marking of mouse neurons with multiple, distinct colors. This method has been adapted to non-neuronal cells in mice and to neurons in fish and flies, but has yet to realize its full potential in the mouse brain. Here, we present several new lines of mice that overcome limitations of the initial lines and an adaptation of the method for use in adeno-associated viral (AAV) vectors. We also provide technical advice about how best to image Brainbow transgenes

Understanding academics’ resistance towards (online) student evaluation

Many higher educational institutions and academic staff are still sceptical about the validity and reliability of student evaluation questionnaires, in particular when these evaluations are completed online. One month after a university-wide implementation from paper to online evaluation across 629 modules, (perceived) resistance and ambivalence amongst academic staff were unpacked. A mixed-method study was conducted amongst 104 academics using survey methods and follow-up semi-structured interviews. Despite a successful ‘technical’ transition (i.e. response rate of 60%, similar scores to previous evaluations), more than half of respondents reported a negative experience with this transition. The results indicate that the multidimensional nature of ambivalence towards change and the dual nature of student evaluations can influence the effectiveness of organisational transition processes