New techniques in linear and non-linear laser optics in muscle research.

This review proposes a brief summary of two applications of lasers to muscle research. The first application (laser tweezers), is now a well-established technique in the field, adopted by several laboratories in the world and producing a constant stream of original data, fundamental for our improved understanding of muscle contraction at the level of detail that only single molecule measurements can provide. As an example of the power of this technique, here we focus on some recent results, revealing the performance of the working stroke in at least two distinct steps also in skeletal muscle myosin. A second laser-based technique described here is second-harmonic generation; the application of this technique to muscle research is very recent. We describe the main results obtained thus far in this area and the potentially remarkable impact that this technology may have in muscle research.