A laser pointer driven microheater for precise local heating and conditional gene regulation in vivo. Microheater driven gene regulation in zebrafish

We describe a simple, highly controllable, and versatile apparatus for heating biological tissue and other materials on the micron-scale. This microheater employs micron-scale fiber optics and uses an inexpensive laser-pointer as a power source. Optical fibers can be pulled on a standard electrode puller to produce tips of varying sizes that can then be used to reliably heat 20-100 μm targets. We demonstrate precise spatiotemporal control of hsp70l:GFP transgene expression in a variety of tissue types in zebrafish embryos and larvae. We also show how this system can be employed as part of a new method for lineage tracing that would greatly facilitate the study of organogenesis and tissue regulation at any time in the life cycle.This versatile and simple local heater has broad utility for the study of gene function and for lineage tracing. This system could be used to control hsp-driven gene expression in any organism simply by bringing the fiber optic tip in contact with the tissue of interest. Beyond these uses for the study of gene function, this device has wide-ranging utility in materials science and could easily be adapted for therapeutic purposes in humans.The study of gene function has been greatly facilitated by the ability to conditionally regulate gene expression at different locations and times throughout the life cycle. A variety of genetic tools that allow such temporal and/or spatial control of gene expression have been developed for study of gene function in several model organisms. These include site-specific recombination using cre or flp recombinases [1-3], tetracycline inducible systems [4], and the Gal4/UAS system [5,6]. Another system for conditional gene regulation takes advantage of the cellular heat shock response, which leads to the transcription of genes that allow cells to tolerate brief periods of stress, or to activate cell death pathways when these stresses are too extreme [7,8]. One particularly well studied heat shock inducible gene i