Mechanical analysis of Drosophila indirect flight and jump muscles

Abstract

The genetic advantages of Drosophila make it a very appealing choice for investigating muscle development, muscle physiology and muscle protein structure and function. To take full advantage of this model organism, it has been vital to develop isolated Drosophila muscle preparations that can be mechanically evaluated. We describe techniques to isolate, prepare and mechanically analyze skinned muscle fibers from two Drosophila muscle types, the indirect flight muscle and the jump muscle. The function of the indirect flight muscle is similar to vertebrate cardiac muscle, to generate power in an oscillatory manner. The indirect flight muscle is ideal for evaluating the influence of protein mutations on muscle and cross-bridge stiffness, oscillatory power, and deriving cross-bridge rate constants. Jump muscle physiology and structure are more similar to skeletal vertebrate muscle than indirect flight muscle, and it is ideal for measuring maximum shortening velocity, force-velocity characteristics and steady-state power generation.

Mapping Interactions between Myosin Relay and Converter Domains That Power Muscle Function

“…Furthermore, the indirect flight muscles can be programmed to express mutated myosins without concern as to the functional consequences because these muscles are not essential for viability (15,16). The indirect flight muscles are amenable to both ultrastructural and physiological analyses (17,18). In addition, myosin can be isolated from these muscles and used to correlate mutant phenotypes with biochemical and biophysical perturbations (14,19).…”

Ral function in muscle is required for flight maintenance in Drosophila

“…29 Thus, we looked at the morphology of the indirect flight muscles in the thorax which consist of dorsal longitudinal muscles (DLMs) and dorsal ventral muscles (DVMs). 30 Mutations in genes required for formation of these muscle fibres can lead to malformed muscle fibres. 31 However, expression of Ral DN with Mef2-GAL4 in all muscles through development and in adults resulted in muscle fibres that look identical to control (Fig.…”

An embryonic myosin converter domain influences Drosophila indirect flight muscle stretch activation, power generation and flight

“…At the time, we were focused on elucidating the influence of the converter on rate constants of the myosin cross-bridge cycle (Swank et al, 2002). Sinusoidal analysis requires that the tension response be linear with the length change, which only holds to about 0.3% change in ML (Swank, 2012). Our 2002 study also differed from our current study in that the skinned fiber bathing solution included only 5 mmol l −1 ATP.…”

“…Fiber preparation for mechanical evaluation was performed as previously described (Swank, 2012). In brief, a bundle of six dorsal longitudinal IFM fibers was removed from a half thorax of a 2-4 day old female fly.…”

“…A sinusoidal length change of 0.125% ML and a frequency set from 0.5 to 650 Hz were applied to the fiber. Power (W m ), E v is the viscous modulus at f, and ΔL/L is the amplitude of the sinusoidal length change divided by the length of the fiber between the two T-clips (Swank, 2012 …”