November 2012: This Month in JoVE

In this issue, Oestreicher et al. show us how to isolate magnetotactic bacteria from freshwater samples, and concentrate the bacteria at one end of a glass capillary. The magnetotactic bacteria can then be visualized by light and transmission electron microscopy, and used for various other assays. Also in the November 2012 issue, Boland et al. demonstrate how to reprogram fibroblasts into induced pluripotent stem cells (iPSCs), and how to isolate iPSC lines for injecting into tetraploid blastocysts, as demonstrated previously in JoVE. While mouth pipetting is generally not recommended because it can have adverse effects, this protocol requires the technique, executed carefully, to manipulate the embryos. This is one of the rare occasions when it's actually OK to mouth pipet in the lab. If the induced cells are fully pluripotent, they can result in full-term mice derived completely from iPSCs. In JoVE Neuroscience, Heermann and Krieglstein demonstrate a method for visualizing Schwann cell development along growing axons. To do this, our authors culture cervical ganglia explants onto collagen matrices, and treat the explants with nerve growth factor or other substances. The collagen gels can then be visualized using time-lapse imaging with fluorescence or bright-field microscopy, migrating along axons towards the periphery. Also in JoVE Neuroscience, Hoffmann et al. put tiny headphones on songbirds to study how they use auditory feedback to adjust their singing. The authors demonstrate how to construct the headphones and attach them to the bird's head; then, by adjusting the acoustic signal, they can study the computational and neurophysiological basis of vocal learning in birds. In JoVE Clinical & Translational Medicine, Iyengar et al. use a zebrafish tumor model to study genes that can modify the pathogenesis of melanoma. This is done by first creating transgenic zebrafish that express a gene of interest. Various assays can then be performed to study how different genes affect melanoma, including onset, invasion, and transplantability. In JoVE Bioengineering, Martin et al. demonstrate a gliding assay to measure the flexural rigidity of biopolymers (such as microtubules). By attaching motor proteins to a microscope slide, and adding fluorescently labeled microtubules, our authors can analyze the dynamics of cytoskeletal polymers. This preview summarizes just a few notable video-articles in the November 2012 issue of JoVE. Stop by throughout the month of November to check out the full length versions of these articles and many more.