Regulation of Oscillatory Contraction in Insect Flight Muscle by Troponin

Kržič, Uroš; Rybin, Vladimir; Leonard, Kevin; Linke, Wolfgang A.; Bullard, Belinda

doi:10.1016/j.jmb.2010.01.039

Cited by 25 publications

(27 citation statements)

References 31 publications

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“…However, sinusoidal analysis did not detect any changes in calcium sensitivity. Lethocerus IFM TnC-F2 (TnC1) expression is also just 10 % of total TnC (Krzic et al 2010), but the mechanical impact of its removal from IFM fibers was very obvious. Isometric tension was reduced by about ~50 % and work production increased two to threefold at pCa 4.75 in chemically extracted fibers with 100 % TnC-F1 compared to wild type (Krzic et al 2010), The magnitude of these differences should easily have been detected by our Drosophila mechanics experiments if TnC1 played as important a mechanical role in Drosophila as it does in Lethocerus IFM.…”

Section: Discussionmentioning

confidence: 99%

“…Activation of the IFM by stretch requires the muscle to be under tension. The higher affinity of TnC1 for TnI, compared to TnC4—attributed to the two TnI binding sites—(Krzic et al 2010), may have the effect of activating the thin filament more rapidly than is the case with TnC4 alone. Conversely, TnC1 may be needed for quickly ending IFM oscillations when a fly lands.…”

Section: Discussionmentioning

confidence: 99%

“…TnC-F2 (TnC1) is needed for the production of maximum isometric tension in Lethocerus IFM (Agianian et al 2004; Krzic et al 2010). We propose that the different results are due to differences in the mechanical characteristics of the IFMs between the two species and how their IFMs are used.…”

Section: Discussionmentioning

confidence: 99%

“…This reasoning is predicated on the proposal that IFM SA can only occur on a partially calcium activated thin filament (Bullard and Pastore 2011; Perz-Edwards et al 2011). Lethocerus produces maximum SA tension at calcium concentrations ~pCa 6.1, that produce sub-maximum calcium activated isometric tension levels (Agianian et al 2004; Krzic et al 2010; Linari et al 2004). Because Lethocerus TnC1 causes increased calcium-activated isometric tension, Lethocerus IFMs have to operate at subsaturating levels of calcium for SA and SD to occur.…”

Section: Discussionmentioning

confidence: 99%

“…TnC1, like the TnC of most invertebrate muscles (Collins 1991), binds two calcium ions, one in the N-domain, which is regulatory, and one with higher affinity in the C-domain (Agianian et al 2004). Previous mechanical measurements with Lethocerus IFM fibers in which TnC isoforms were exchanged within the troponin complex suggest that TnC4 (TnC-F1 in Lethocerus IFM) is required for SA, while TnC1 (TnC-F2 in Lethocerus IFM) is required for calcium -activated isometric tension (Agianian et al 2004; Krzic et al 2010). …”

Section: Introductionmentioning

confidence: 99%

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The roles of troponin C isoforms in the mechanical function of Drosophila indirect flight muscle

Eldred

Katzemich

Patel

et al. 2014

J Muscle Res Cell Motil

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Stretch activation (SA) is a fundamental property of all muscle types that increases power output and efficiency, yet its mechanism is unknown. Recently, studies have implicated troponin isoforms as important in the SA mechanism. The highly stretch-activated Drosophila IFMs express two isoforms of the Ca2+-binding subunit of troponin (TnC). TnC1 (TnC-F2 in Lethocerus IFM) has two calcium binding sites, while an unusual isoform, TnC4 (TnC-F1 in Lethocerus IFM), has only one binding site. We investigated the roles of these two TnC isoforms in Drosophila IFM by targeting RNAi to each isoform. IFMs with TnC4 expression (normally ~90 % of total TnC) replaced by TnC1 did not generate isometric tension, power or display SA. However, TnC4 knockdown resulted in sarcomere ultrastructure disarray, which could explain the lack of mechanical function and thus make interpretation of the influence of TnC4 on SA difficult. Elimination of TnC1 expression (normally ~10 % of total TnC) by RNAi resulted in normal muscle structure. In these IFMs, fiber power generation, isometric tension, stretch-activated force and calcium sensitivity were statistically identical to wild type. When TnC1 RNAi was driven by an IFM specific driver, there was no decrease in flight ability or wing beat frequency, which supports our mechanical findings suggesting that TnC1 is not essential for the mechanical function of Drosophila IFM. This finding contrasts with previous work in Lethocerus IFM showing TnC1 is essential for maximum isometric force generation. We propose that differences in TnC1 function in Lethocerus and Drosophila contribute to the ~40-fold difference in IFM isometric tension generated between these species.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

The roles of troponin C isoforms in the mechanical function of Drosophila indirect flight muscle

Eldred

Katzemich

Patel

et al. 2014

J Muscle Res Cell Motil

Self Cite

View full text Add to dashboard Cite

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Applications of isothermal titration calorimetry in pure and applied research—survey of the literature from 2010

Ghai

Falconer

Collins

2011

J of Molecular Recognition

167

108

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Isothermal titration calorimetry (ITC) is a biophysical technique for measuring the formation and dissociation of molecular complexes and has become an invaluable tool in many branches of science from cell biology to food chemistry. By measuring the heat absorbed or released during bond formation, ITC provides accurate, rapid, and label-free measurement of the thermodynamics of molecular interactions. In this review, we survey the recent literature reporting the use of ITC and have highlighted a number of interesting studies that provide a flavour of the diverse systems to which ITC can be applied. These include measurements of protein-protein and protein-membrane interactions required for macromolecular assembly, analysis of enzyme kinetics, experimental validation of molecular dynamics simulations, and even in manufacturing applications such as food science. Some highlights include studies of the biological complex formed by Staphylococcus aureus enterotoxin C3 and the murine T-cell receptor, the mechanism of membrane association of the Parkinson's disease-associated protein α-synuclein, and the role of non-specific tannin-protein interactions in the quality of different beverages. Recent developments in automation are overcoming limitations on throughput imposed by previous manual procedures and promise to greatly extend usefulness of ITC in the future. We also attempt to impart some practical advice for getting the most out of ITC data for those researchers less familiar with the method.

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Neural control and precision of flight muscle activation in Drosophila

Lehmann

Bartussek

2016

J Comp Physiol A

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Precision of motor commands is highly relevant in a large context of various locomotor behaviors, including stabilization of body posture, heading control and directed escape responses. While posture stability and heading control in walking and swimming animals benefit from high friction via ground reaction forces and elevated viscosity of water, respectively, flying animals have to cope with comparatively little aerodynamic friction on body and wings. Although low frictional damping in flight is the key to the extraordinary aerial performance and agility of flying birds, bats and insects, it challenges these animals with extraordinary demands on sensory integration and motor precision. Our review focuses on the dynamic precision with which Drosophila activates its flight muscular system during maneuvering flight, considering relevant studies on neural and muscular mechanisms of thoracic propulsion. In particular, we tackle the precision with which flies adjust power output of asynchronous power muscles and synchronous flight control muscles by monitoring muscle calcium and spike timing within the stroke cycle. A substantial proportion of the review is engaged in the significance of visual and proprioceptive feedback loops for wing motion control including sensory integration at the cellular level. We highlight that sensory feedback is the basis for precise heading control and body stability in flies.

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Regulation of Oscillatory Contraction in Insect Flight Muscle by Troponin

Cited by 25 publications

References 31 publications

The roles of troponin C isoforms in the mechanical function of Drosophila indirect flight muscle

The roles of troponin C isoforms in the mechanical function of Drosophila indirect flight muscle

Applications of isothermal titration calorimetry in pure and applied research—survey of the literature from 2010

Neural control and precision of flight muscle activation in Drosophila

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