Chan W P, Dickinson M H
Department of Intergrative Biology, University of California, Berkeley 94720, USA.
J Exp Biol. 1996 Dec;199(Pt 12):2767-74. doi: 10.1242/jeb.199.12.2767.
We have used high-speed video microscopy to measure in vivo length oscillations of the indirect flight muscles of the fruit fly Drosophila virilis during tethered flight. The changes in muscle strain were measured by tracking the deformation of the thoracic exoskeleton at the origin and insertion of both the dorsal longitudinal (DLM) and the dorsal ventral (DVM) muscles. The mean peak-to-peak strain amplitudes were found to be 3.5% for the DLMs and 3.3% for the DVMs, although the strain amplitude within individual cycles ranged from 2 to 5%. These values are consistent with the small number of previous measurements of indirect flight muscle strain in other insects, but almost an order of magnitude greater than the strain amplitudes used in most biophysical studies of skinned Drosophila fibers. The results suggest that serial compliance within this sarcomere would need to relieve approximately 70% of the total strain in order for individual crossbridges to remain attached throughout a complete contraction-extension cycle.
我们利用高速视频显微镜测量了系留飞行期间果蝇（Drosophila virilis）间接飞行肌的体内长度振荡。通过追踪背纵肌（DLM）和背腹肌（DVM）在其起点和止点处的胸部外骨骼变形来测量肌肉应变变化。发现DLM的平均峰峰值应变幅度为3.5%，DVM为3.3%，尽管单个周期内的应变幅度在2%至5%之间。这些值与之前对其他昆虫间接飞行肌应变的少量测量结果一致，但几乎比大多数对去皮果蝇纤维进行的生物物理研究中使用的应变幅度大一个数量级。结果表明，为了使单个横桥在整个完整的收缩-伸展周期中保持附着，该肌节内的串联顺应性需要缓解约70%的总应变。
