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Drosophila is a well-established genetic model organism: thousands of point mutations, deficiencies or transposon insertions are available from stock centres. However, to date, it is still difficult to modify a specific gene locus in a defined manner. A potential solution is the application of transcription activator-like effector nucleases (TALENs), which have been used successfully to mutate genes in various model organisms. TALENs are constructed by fusion of TALE proteins to the endonuclease FokI, resulting in artificial, sequence-specific endonucleases. They induce double strand breaks, which are either repaired by error-prone non-homologous end joining (NHEJ) or homology directed repair (HDR). We developed a simple TALEN-based protocol to mutate any gene of interest in Drosophila within approximately 2 months. We inject mRNA coding for two TALEN pairs targeting the same gene into embryos, employ T7 endonuclease I screening of pooled F1 flies to identify mutations and generate a stable mutant stock in the F3 generation. We illustrate the efficacy of our strategy by mutating CG11617, a previously uncharacterized putative transcription factor with an unknown function in Drosophila. This demonstrates that TALENs are a reliable and efficient strategy to mutate any gene of interest in Drosophila., (Copyright © 2014 Elsevier Inc. All rights reserved.)

The development and molecular composition of muscle tissue is evolutionarily conserved. Drosophila is a powerful in vivo model system to investigate muscle morphogenesis and function. Here, we provide a short and comprehensive overview of the important developmental steps to build Drosophila body muscle in embryos, larvae and pupae. We describe key methods, including muscle histology, live imaging and genetics, to study these steps at various developmental stages and include simple behavioural assays to assess muscle function in larvae and adults. We list valuable antibodies and fly strains that can be used for these different methods. This overview should guide the reader to choose the best marker or the appropriate method to obtain high quality muscle morphogenesis data in Drosophila., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Muscles coordinate body movements throughout the animal kingdom. Each skeletal muscle is built of large, multi-nucleated cells, called myofibers, which are classified into several functionally distinct types. The typical fiber-type composition of each muscle arises during development, and in mammals is extensively adjusted in response to postnatal exercise. Understanding how functionally distinct muscle fiber-types arise is important for unraveling the molecular basis of diseases from cardiomyopathies to muscular dystrophies. In this review, we focus on recent advances in Drosophila and mammals in understanding how muscle fiber-type specification is controlled by the regulation of transcription and alternative splicing. We illustrate the cooperation of general myogenic transcription factors with muscle fiber-type specific transcriptional regulators as a basic principle for fiber-type specification, which is conserved from flies to mammals. We also examine how regulated alternative splicing of sarcomeric proteins in both flies and mammals can directly instruct the physiological and biophysical differences between fiber-types. Thus, research in Drosophila can provide important mechanistic insight into muscle fiber specification, which is relevant to homologous processes in mammals and to the pathology of muscle diseases., (© 2013 The Authors. Published by Elsevier Inc. All rights reserved.)