Este mes de noviembre en JoVe

The November issue of the Journal of Visualized Experiments begins with a series of behavioral experiments for measuring prehension ability in primates. Investigators from the University of Fribourg demonstrate four grasping and reaching tasks, which all follow common steps for comfortably restraining the animal and correctly positioning its head. The Brinkman Board test is used to assess reaching for static objects, while the Rotating Brinkman Board presents a condition where animals need to anticipate object position. The Brinkman Box test allows dexterity to be investigated under conditions where the monkey has fewer degrees of freedom to perform grasping task and cannot use vision to guide movement. While the brinkman board and box tests solely rely on analysis of video obtained during experiments, in order to generate data, the drawer reaching task apparatus has detectors that monitor grip and load forces as well as drawer position, making this test appropriate for measuring strength as well as prehension ability. In combination, these four tests provide a powerful approach to assess motor control in the distal forelimb, and the Fribourg group presents data from both lesion studies and experiments aimed to test potential therapies for spinal cord injury.

In Clinical and Translational Medicine, collaborators from the Division of Surgical Research at the University Hospital Zurich and the Institute of Laboratory Animal Science at the University of Zurich, work together to implant a radiotelemetry device in mice, which can be used to take physiological measurements in freely moving animals. The devices consist of two leads, which are capable of measuring biopotential activity (ECG, EEG, or EMG) as well as temperature, and a lightweight radio transmitter (1-200 Hz in bandwidth) that can be implanted in the abdominal cavity. The stress of animal handling as well as anesthesia are known confounding elements, which impact physiological measurements, so radiotelemetry devices are a convenient way to acquire physiological data from animals in an unperturbed, natural state, as well as take measurements of multiple animals, simultaneously.

JoVE also adds to its host of electroporation protocols with a method for introducing macromoledules into the craniofacial mesenchyme of developing Xenopus laevis tadpoles, from the Liu Lab at King’s College London. Xenopus tadpoles are transferred to an electroporation chamber, where they can be injected with nucleic acid, and then subjected to electroporation, which will deliver expression vectors or morpholinos into the developing craniofacial tissue. Gene delivery into differentiated cartilage is inherently problematic, and the Liu lab shows that, through elecroporation, morpholinos can be introduced into procartilaginous and cartilaginous tissues of the Xenopus tadpole throughout a range of developmental stages.

In Bioengineering, the Zuckerman group from the Lawrence Berkeley National Laboratory illustrates their method for synthesizing peptoids, a class of biologically-active organic molecules that resemble peptides, but have their side chains attached to the nitrogen of the peptide bond, rather than the alpha carbon, which makes them resistant to proteolysis. The Zuckerman group demonstrates submonomer synthesis, where peptide monomers are added sequentially in bromoacetylation and bromide displacement reactions, allowing peptoid chain length and composition to be precisely controlled. Furthermore, the fact that synthesis is done on amide resin, and is hence, solid phase synthesis, greatly simplifies purification of the synthesized peptoids. These authors also show how the newly-synthesized peptoids can be induced to self-assemble into highly-ordered structures, termed nanosheets, which can be visualized by fluorescence and scanning electron microscopy. These nanosheets could serve as a potential platform for protein and membrane mimetics.

Later in the month, JoVE features an assay for measuring phagocytic activity in cells exposed to clinical antibody samples for our Immunology and Infection section. Collaborators from Massachusetts General Hospital and Dartmouth College show that THP-1 cells will engulf antibody-bound antigen coated beads in timelapse video microscopy and present a plate-based flow cytometry method for quantifying the extent of phagocytosis. Our authors use this method to determine the ability of different antibody samples to induce phagocytosis, such as those from HIV patients both treated and untreated with anti-retroviral therapies.

This summary of JoVE’s content in November provides a brief overview of JoVE’s highlights for the month. Other noteworthy articles include methods for live imaging of cytoskeletal dynamics in endothelial cells, measuring calcium flux in cardiomyocytes, and slice electrophysiology of adult born neurons in the olfactory bulb.