Understanding stretch activation and shortening deactivation in drosophila melanogaster
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Authors
Loya, Amy K.
Issue Date
2020-12
Type
Electronic thesis
Thesis
Thesis
Language
ENG
Keywords
Biomedical engineering
Alternative Title
Abstract
Generating high, sustained power from a muscle undergoing a cyclical lengthening and shortening contraction pattern requires fast yet efficient activation and relaxation rates. To enhance activation and force levels during contraction, some muscle types have evolved stretch activation (SA), a delayed increase in force following rapid muscle lengthening. While SA has been investigated for decades, its complementary phenomenon, shortening deactivation (SD), a delayed decrease in force following muscle shortening, has not been directly measured. Together, these properties play an important role in increasing power production and efficiency in cyclically contracting muscles, namely Drosophila indirect flight muscles (IFM), Lethocerus IFM, and vertebrate hearts. In the first study of this dissertation, to enable mechanistic investigations into SD and compare it to SA, we developed a protocol to elicit SA and SD in skinned muscle fibers from three muscles: the high SA Drosophila and Lethocerus IFM, and low SA Drosophila jump muscle. In the second study, we investigated an unusual troponin C (TnC) isoform (TnC4) found in IFM, which has only one calcium binding site and has been proposed to play a critical role in SA. We analyzed the effects of replacing the TnC isoform (TnC1) native to the Drosophila jump muscle with TnC4 in order to identify functional changes that could explain how a muscle with minimal SA capacity might acquire the characteristics of muscle types with high SA.
Description
December 2020
School of Engineering
School of Engineering
Full Citation
Publisher
Rensselaer Polytechnic Institute, Troy, NY