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Wing polymorphism and dispersal of Scaptocoris carvalhoi (Hemiptera : Cydnidae)

NARDI, Cristiane; FERNANDES, Paulo Marcal; BENTO, Jose Mauricio Simoes
Fonte: ENTOMOLOGICAL SOC AMER Publicador: ENTOMOLOGICAL SOC AMER
Tipo: Artigo de Revista Científica
ENG
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Functional wing polymorphism is commonly observed it) insects, and it may confer an important adaptive value to populations that bear this trait, because it allows dispersal and the location to more favorable habitats for their survival and reproduction. According to the oogenesis-flight syndrome theory, such wing polymorphism may imply differences in the locomotion Capacity of individuals, which is a factor induced by adverse environmental conditions during muscle development in immatures. Scaptocoris carvalhoi Becker (Hemiptera: Cydnidae) is an important agriculture pest in Brazil, and it has burrowing habits. The adults swarm in the beginning of the rainy season after a prolonged drought period in the Brazilian cerrado region. In these swarms, part of the population leaves the soil, performing long flights until locations with more abundant vegetation. In this study, we characterized wing polymorphism in S. carvalhoi, this being the first description in a species of Cydnidae. Brachypterous and macropterous males and females were observed, which showed positive and significant correlations between body length and hindwing length. Macropterous individuals demonstrated greater locomotion capacity than brachypterous individuals. In addition...

Mechanisms Involved in 3 `,5 `-Cyclic Adenosine Monophosphate-Mediated Inhibition of the Ubiquitin-Proteasome System in Skeletal Muscle

GONCALVES, Dawit A. P.; LIRA, Eduardo C.; BAVIERA, Amanda M.; CAO, Peirang; ZANON, Neusa M.; ARANY, Zoltan; BEDARD, Nathalie; TANKSALE, Preeti; WING, Simon S.; LECKER, Stewart H.; KETTELHUT, Isis C.; NAVEGANTES, Luiz C. C.
Fonte: ENDOCRINE SOC Publicador: ENDOCRINE SOC
Tipo: Artigo de Revista Científica
ENG
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Although it is well known that catecholamines inhibit skeletal muscle protein degradation, the molecular underlying mechanism remains unclear. This study was undertaken to investigate the role of beta(2)-adrenoceptors (AR) and cAMP in regulating the ubiquitin-proteasome system (UPS) in skeletal muscle. We report that increased levels of cAMP in isolated muscles, promoted by the cAMP phosphodiesterase inhibitor isobutyl methylxanthine was accompanied by decreased activity of the UPS, levels of ubiquitin-protein conjugates, and expression of atrogin-1, a key ubiquitin-protein ligase involved in muscle atrophy. In cultured myotubes, atrogin-1 induction after dexamethasone treatment was completely prevented by isobutyl methylxanthine. Furthermore, administration of clenbuterol, a selective beta(2)-agonist, to mice increased muscle cAMP levels and suppressed the fasting-induced expression of atrogin-1 and MuRF-1, atrogin-1 mRNA being much more responsive to clenbuterol. Moreover, clenbuterol increased the phosphorylation of muscle Akt and Foxo3a in fasted rats. Similar responses were observed in muscles exposed to dibutyryl-cAMP. The stimulatory effect of clenbuterol on cAMP and Akt was abolished in muscles from beta(2)-AR knockout mice. The suppressive effect of beta(2)-agonist on atrogin-1 was not mediated by PGC-1 alpha (peroxisome proliferator-activated receptor-gamma coactivator 1 alpha known to be induced by beta(2)-agonists and previously shown to inhibit atrogin-1 expression)...

Estudo termográfico e histomorfométrico do enxerto pediculado do músculo peitoral superficial sobre região de excisão parcial do músculo bíceps braquial em pombos (Columba livia); Termographic and histomorphometric study of superficial pectoral muscle pediculated graft over the region of parcial excision of the brachial biceps muscle in pigeons

Ferraz, Vanessa Couto de Magalhães
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 28/06/2013 PT
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Traumas nas asas de aves são muito comuns, causando lesões em tecidos moles e ossos, e tendem, muitas vezes a causar desvascularização da região, o que implica em complicação no tratamento além de facilitar a instalação de processo infeccioso. Com o objetivo de estudar possível vascularização via enxerto muscular pediculado, foram utilizados 12 pombos, divididos em dois grupos iguais (E e S), para a avaliação do uso de enxerto pediculado de músculo peitoral como técnica de revascularização de defeito criado em porção distal de bíceps braquial. As asas contralaterais de todos os animais foram utilizadas para a avaliação termográfica, sendo este grupo de n=12 denominado C. As asas contralaterais de dois animais foram utilizadas como controle anatômico para a avaliação histomorfométrica, grupo este denominado A. Realizaram-se avaliações clínica, termográfica, angiográfica e histomorfométrica para quantificação e qualificação da vascularização, e determinação da viabilidade desta técnica, em até vinte e um dias. A técnica causou pouca morbidade, exceto em dois animais do grupo E que apresentaram necrose parcial do enxerto, porém isto não resultou em falha da técnica. As avaliações termográficas demonstraram que imediatamente após a cirurgia...

Increase in levels of polyubiquitin and proteasome mRNA in skeletal muscle during starvation and denervation atrophy.

Medina, R; Wing, S S; Goldberg, A L
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 01/05/1995 EN
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Most of the increased protein degradation in muscle atrophy caused by starvation and denervation is due to activation of a non-lysosomal ATP-dependent proteolytic process. To determine whether expression of the ubiquitin-proteasome-dependent pathway is activated in atrophying muscles, we measured the levels of mRNA for ubiquitin (Ub) and proteasome subunits, and Ub content. After rats had been deprived of food for 1 or 2 days, the concentration of the two polyubiquitin (polyUb) transcripts increased 2-4-fold in the pale extensor digitorum longus muscle and 1-2.5-fold in the red soleus, whereas total muscle RNA and total mRNA content fell by 50%. After denervation of the soleus, there was a progressive 2-3-fold increase in polyUb mRNA for 1-3 days, whereas total RNA content fell. On starvation or denervation, Ub concentration in the muscles also rose by 60-90%. During starvation, polyUb mRNA levels also increased in heart, but not in liver, kidney, spleen, fat, brain or testes. Although the polyUb gene is a heat-shock gene that is induced in muscles under certain stressful conditions, the muscles of starving rats or after denervation did not express other heat-shock genes. On starvation or denervation, mRNA for several proteasome subunits (C-1...

Alternative N-Terminal Regions of Drosophila Myosin Heavy Chain Tune Muscle Kinetics for Optimal Power Output

Swank, Douglas M.; Kronert, William A.; Bernstein, Sanford I.; Maughan, David W.
Fonte: Biophysical Society Publicador: Biophysical Society
Tipo: Artigo de Revista Científica
Publicado em /09/2004 EN
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We assessed the influence of alternative versions of a region near the N-terminus of Drosophila myosin heavy chain on muscle mechanical properties. Previously, we exchanged N-terminal regions (encoded by alternative exon 3s) between an embryonic (EMB) isoform and the indirect flight muscle isoform (IFI) of myosin, and demonstrated that it influences solution ATPase rates and in vitro actin sliding velocity. Because each myosin is expressed in Drosophila indirect flight muscle, in the absence of other myosin isoforms, this allows for muscle mechanical and whole organism locomotion assays. We found that exchanging the flight muscle specific exon 3 region into the embryonic isoform (EMB-3b) increased maximum power generation (Pmax) and optimal frequency of power generation (fmax) threefold and twofold compared to fibers expressing EMB, whereas exchanging the embryonic exon 3 region into the flight muscle isoform (IFI-3a) decreased Pmax and fmax to ∼80% of IFI fiber values. Drosophila expressing IFI-3a exhibited a reduced wing beat frequency compared to flies expressing IFI, which optimized power generation from their kinetically slowed flight muscle. However, the slower wing beat frequency resulted in a substantial loss of aerodynamic power as manifest in decreased flight performance of IFI-3a compared to IFI. Thus the N-terminal region is important in tuning myosin kinetics to match muscle speed for optimal locomotory performance.

Stepping before standing: hip muscle function in stepping and standing balance after stroke

Kirker, S; Simpson, D; Jenner, J; Wing, A
Fonte: BMJ Group Publicador: BMJ Group
Tipo: Artigo de Revista Científica
Publicado em /04/2000 EN
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36.05%
OBJECTIVE—To compare the pattern of pelvic girdle muscle activation in normal subjects and hemiparetic patients while stepping and maintaining standing balance.
DESIGN—Group comparison.
METHOD—Seventeen patients who had regained the ability to walk after a single hemiparetic stroke were studied together with 16 normal controls. Median interval between stroke and testing was 17 months. Amplitude and onset latency of surface EMG activity in hip abductors and adductors were recorded in response to sideways pushes in either direction while standing. Similar recordings were made in the same subjects during gait initiation and a single stride.
RESULTS—In the standing balance task, normal subjects resisted a sideways push to the left with the left gluteus medius (74 ms) and with the right adductor (111 ms), and vice versa. In hemiparetic patients, the amplitude of activity was reduced in the hemiparetic muscles, the onset latencies of which were delayed (gluteus medius 96 ms, adductor 144 ms). Contralateral, non-paretic, adductor activity was increased after a push towards the hemiparetic side of patients with stroke and the latency was normal (110 ms). During self initiated sideways weight shifts at gait initiation, hemiplegic muscle activation was impaired. By contrast...

Fed-state clamp stimulates cellular mechanisms of muscle protein anabolism and modulates glucose disposal in normal men

Adegoke, Olasunkanmi A. J.; Chevalier, Stéphanie; Morais, José A.; Gougeon, Réjeanne; Kimball, Scot R.; Jefferson, Leonard S.; Wing, Simon S.; Marliss, Errol B.
Fonte: American Physiological Society Publicador: American Physiological Society
Tipo: Artigo de Revista Científica
EN
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36.05%
Since maximum anabolism occurs postprandially, we developed a simulated fed state with clamped hyperinsulinemia, physiological hyperglycemia, and hyperaminoacidemia (Hyper-3) and explored muscle cellular mechanisms. Whole body [1-13C]leucine and [3-3H]glucose kinetics in healthy men were compared between hyperinsulinemic, euglycemic, isoaminoacidemic (Hyper-1, n = 10) and Hyper-3 (n = 9) clamps. In Hyper-3 vs. Hyper-1, nonoxidative leucine Rd [rate of disappearance (synthesis)] was stimulated more (45 ± 4 vs. 24 ± 4 μmol/min, P < 0.01) and endogenous Ra [rate of appearance (breakdown)] was inhibited similarly; hence net balance increased more (86 ± 6 vs. 49 ± 2 μmol/min, P < 0.001). Glucose Rd was similar; thus Hyper-3 metabolic clearance rate (331 ± 23 vs. 557 ± 41 ml/min, P < 0.0005) and Rd/insulin (M, 0.65 ± 0.10 vs. 1.25 ± 0.10 mg·min−1·pmol−1·l, P < 0.001) were less, despite higher insulin (798 ± 74 vs. 450 ± 24 pmol/l, P < 0.005). In vastus lateralis muscle biopsies, phosphorylation of Akt (P = 0.025), mammalian target of rapamycin (mTOR), ribosomal protein S6 kinase (p70S6K1; P = 0.008), S6 (P = 0.049), and 4E-binding protein 1 (4E-BP1; P = 0.001) increased. With decreased eukaryotic initiation factor-4E (eIF4E)·4E-BP1 complex (P = 0.01)...

Disrupting the Myosin Converter-Relay Interface Impairs Drosophila Indirect Flight Muscle Performance

Ramanath, Seemanti; Wang, Qian; Bernstein, Sanford I.; Swank, Douglas M.
Fonte: The Biophysical Society Publicador: The Biophysical Society
Tipo: Artigo de Revista Científica
Publicado em 07/09/2011 EN
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Structural interactions between the myosin converter and relay domains have been proposed to be critical for the myosin power stroke and muscle power generation. We tested this hypothesis by mutating converter residue 759, which interacts with relay residues I508, N509, and D511, to glutamate (R759E) and determined the effect on Drosophila indirect flight muscle mechanical performance. Work loop analysis of mutant R759E indirect flight muscle fibers revealed a 58% and 31% reduction in maximum power generation (PWL) and the frequency at which maximum power (fWL) is generated, respectively, compared to control fibers at 15°C. Small amplitude sinusoidal analysis revealed a 30%, 36%, and 32% reduction in mutant elastic modulus, viscous modulus, and mechanical rate constant 2πb, respectively. From these results, we infer that the mutation reduces rates of transitions through work-producing cross-bridge states and/or force generation during strongly bound states. The reductions in muscle power output, stiffness, and kinetics were physiologically relevant, as mutant wing beat frequency and flight index decreased about 10% and 45% compared to control flies at both 15°C and 25°C. Thus, interactions between the relay loop and converter domain are critical for lever-arm and catalytic domain coordination...

Molecular Assembly and Biosynthesis of Acetylcholinesterase in Brain and Muscle: the Roles of t-peptide, FHB Domain, and N-linked Glycosylation

Chen, Vicky P.; Luk, Wilson K. W.; Chan, Wallace K. B.; Leung, K. Wing; Guo, Ava J. Y.; Chan, Gallant K. L.; Xu, Sherry L.; Choi, Roy C. Y.; Tsim, Karl W. K.
Fonte: Frontiers Research Foundation Publicador: Frontiers Research Foundation
Tipo: Artigo de Revista Científica
Publicado em 25/10/2011 EN
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Acetylcholinesterase (AChE) is responsible for the hydrolysis of the neurotransmitter, acetylcholine, in the nervous system. The functional localization and oligomerization of AChE T variant are depending primarily on the association of their anchoring partners, either collagen tail (ColQ) or proline-rich membrane anchor (PRiMA). Complexes with ColQ represent the asymmetric forms (A12) in muscle, while complexes with PRiMA represent tetrameric globular forms (G4) mainly found in brain and muscle. Apart from these traditional molecular forms, a ColQ-linked asymmetric form and a PRiMA-linked globular form of hybrid cholinesterases (ChEs), having both AChE and BChE catalytic subunits, were revealed in chicken brain and muscle. The similarity of various molecular forms of AChE and BChE raises interesting question regarding to their possible relationship in enzyme assembly and localization. The focus of this review is to provide current findings about the biosynthesis of different forms of ChEs together with their anchoring proteins.

Calcium and Stretch Activation Modulate Power Generation in Drosophila Flight Muscle

Wang, Qian; Zhao, Cuiping; Swank, Douglas M.
Fonte: The Biophysical Society Publicador: The Biophysical Society
Tipo: Artigo de Revista Científica
Publicado em 02/11/2011 EN
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Many animals regulate power generation for locomotion by varying the number of muscle fibers used for movement. However, insects with asynchronous flight muscles may regulate the power required for flight by varying the calcium concentration ([Ca2+]). In vivo myoplasmic calcium levels in Drosophila flight muscle have been found to vary twofold during flight and to correlate with aerodynamic power generation and wing beat frequency. This mechanism can only be possible if [Ca2+] also modulates the flight muscle power output and muscle kinetics to match the aerodynamic requirements. We found that the in vitro power produced by skinned Drosophila asynchronous flight muscle fibers increased with increasing [Ca2+]. Positive muscle power generation started at pCa = 5.8 and reached its maximum at pCa = 5.25. A twofold variation in [Ca2+] over the steepest portion of this curve resulted in a two- to threefold variation in power generation and a 1.2-fold variation in speed, matching the aerodynamic requirements. To determine the mechanism behind the variation in power, we analyzed the tension response to muscle fiber-lengthening steps at varying levels of [Ca2+]. Both calcium-activated and stretch-activated tensions increased with increasing [Ca2+]. However...

Elastic Modulus of Muscle and Tendon with Shear Wave Ultrasound Elastography: Variations with Different Technical Settings

Kot, Brian Chin Wing; Zhang, Zhi Jie; Lee, Arthur Wai Chun; Leung, Vivian Yee Fong; Fu, Siu Ngor
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 31/08/2012 EN
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36.08%
Standardization on Shear wave ultrasound elastography (SWUE) technical settings will not only ensure that the results are accurate, but also detect any differences over time that may be attributed to true physiological changes. The present study evaluated the variations of elastic modulus of muscle and tendon using SWUE when different technical aspects were altered. The results of this study indicated that variations of elastic modulus of muscle and tendon were found when different transducer’s pressure and region of interest (ROI)’s size were applied. No significant differences in elastic modulus of the rectus femoris muscle and patellar tendon were found with different acquisition times of the SWUE sonogram. The SWUE on the muscle and tendon should be performed with the lightest transducer’s pressure, a shorter acquisition time for the SWUE sonogram, while measuring the mean elastic modulus regardless the ROI’s size.

Three-dimensional electron microscopic reconstruction of intracellular organellar arrangements in vascular smooth muscle – further evidence of nanospaces and contacts

Tong, Wing Chiu; Sweeney, Michele; Jones, Carolyn J P; Zhang, Henggui; O’Neill, Stephen C; Prior, Ian; Taggart, Michael J
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
EN
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36.05%
The sarcoplasmic reticulum (SR) of smooth muscle is crucial for appropriate regulation of Ca2+ signalling. In visceral and vascular smooth muscles the SR is known to periodically lie in close register, within a few nanometres, to the plasma membrane. Recent work has focussed on reconstructions of the ultrastructural arrangement of this so-called peripheral SR that may be important for the genesis of phenomena such as Ca2+ sparks. Here, we turn our attention to vascular smooth muscle and explore the 3-dimensional (3D) ultrastructural positioning of SR found deeper in the cell that is involved in the propagation of Ca2+ waves. We use digital reconstruction and volume rendering of serial electron microscopic sections from isolated resistance arteries, pressurized in vitro to mimic cellular geometric conformations anticipated in vivo, to map SR positioning. We confirm that these central portions of SR are in close register with mitochondria and the nucleus with all three organelles tightly enveloped by a myofilament/cytoskeletal lattice. Nanospacings between the SR and individual mitochondria are visible and in three dimensions as the SR contorts to accommodate these organelles. Direct connection of the SR and nuclear membranes is confirmed. Such 3D positioning of centrally located SR further informs us of its likely role in the manifestation of spatiotemporal Ca2+ dynamics: signal encoding may be facilitated by spatially directed release of Ca2+ to influence several processes crucial to vascular smooth muscle and resistance artery function including myofilament activation by Ca2+ waves...

Elevated FGF21 secretion, PGC-1α and ketogenic enzyme expression are hallmarks of iron–sulfur cluster depletion in human skeletal muscle

Crooks, Daniel R.; Natarajan, Thanemozhi G.; Jeong, Suh Young; Chen, Chuming; Park, Sun Young; Huang, Hongzhan; Ghosh, Manik C.; Tong, Wing-Hang; Haller, Ronald G.; Wu, Cathy; Rouault, Tracey A.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
EN
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36.1%
Iron–sulfur (Fe-S) clusters are ancient enzyme cofactors found in virtually all life forms. We evaluated the physiological effects of chronic Fe-S cluster deficiency in human skeletal muscle, a tissue that relies heavily on Fe-S cluster-mediated aerobic energy metabolism. Despite greatly decreased oxidative capacity, muscle tissue from patients deficient in the Fe-S cluster scaffold protein ISCU showed a predominance of type I oxidative muscle fibers and higher capillary density, enhanced expression of transcriptional co-activator PGC-1α and increased mitochondrial fatty acid oxidation genes. These Fe-S cluster-deficient muscles showed a dramatic up-regulation of the ketogenic enzyme HMGCS2 and the secreted protein FGF21 (fibroblast growth factor 21). Enhanced muscle FGF21 expression was reflected by elevated circulating FGF21 levels in the patients, and robust FGF21 secretion could be recapitulated by respiratory chain inhibition in cultured myotubes. Our findings reveal that mitochondrial energy starvation elicits a coordinated response in Fe-S-deficient skeletal muscle that is reflected systemically by increased plasma FGF21 levels.

Evaluation of blood and muscle tissues for molecular detection and characterization of hematozoa infections in northern pintails (Anas acuta) wintering in California

Ramey, Andrew M.; Fleskes, Joseph P.; Schmutz, Joel A.; Yabsley, Michael J.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em 05/03/2013 EN
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36.24%
Information on the molecular detection of hematozoa from different tissue types and multiple years would be useful to inform sample collection efforts and interpret results of meta-analyses or investigations spanning multiple seasons. In this study, we tested blood and muscle tissue collected from northern pintails (Anas acuta) during autumn and winter of different years to evaluate prevalence and genetic diversity of Leucocytozoon, Haemoproteus, and Plasmodium infections in this abundant waterfowl species of the Central Valley of California. We first compared results for paired blood and wing muscle samples to assess the utility of different tissue types for molecular investigations of haemosporidian parasites. Second, we explored inter-annual variability of hematozoa infection in Central Valley northern pintails and investigated possible effects of age, sex, and sub-region of sample collection on estimated parasite detection probability and prevalence. We found limited evidence for differences between tissue types in detection probability and prevalence of Leucocytozoon, Haemoproteus, and Plasmodium parasites, which supports the utility of both sample types for obtaining information on hematozoan infections. However, we detected 11 haemosporidian mtDNA cyt b haplotypes in blood samples vs. six in wing muscle tissue collected during the same sample year suggesting an advantage to using blood samples for investigations of genetic diversity. Estimated prevalence of Leucocytozoon parasites was greater during 2006–2007 as compared to 2011–2012 and four unique haemosporidian mtDNA cyt b haplotypes were detected in the former sample year but not in the latter. Seven of 15 mtDNA cyt b haplotypes detected in northern pintails had 100% identity with previously reported hematozoa lineages detected in waterfowl (Haemoproteus and Leucocytozoon) or other avian taxa (Plasmodium) providing support for lack of host specificity for some parasite lineages.

Deletion of Drosophila muscle LIM protein decreases flight muscle stiffness and power generation

Clark, Kathleen A.; Lesage-Horton, Heather; Zhao, Cuiping; Beckerle, Mary C.; Swank, Douglas M.
Fonte: American Physiological Society Publicador: American Physiological Society
Tipo: Artigo de Revista Científica
EN
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36.14%
Muscle LIM protein (MLP) can be found at the Z-disk of sarcomeres where it is hypothesized to be involved in sensing muscle stretch. Loss of murine MLP results in dilated cardiomyopathy, and mutations in human MLP lead to cardiac hypertrophy, indicating a critical role for MLP in maintaining normal cardiac function. Loss of MLP in Drosophila (mlp84B) also leads to muscle dysfunction, providing a model system to examine MLP's mechanism of action. Mlp84B-null flies that survive to adulthood are not able to fly or beat their wings. Transgenic expression of the mlp84B gene in the Mlp84B-null background rescues flight ability and restores wing beating ability. Mechanical analysis of skinned flight muscle fibers showed a 30% decrease in oscillatory power production and a slight increase in the frequency at which maximum power is generated for fibers lacking Mlp84B compared with rescued fibers. Mlp84B-null muscle fibers displayed a 25% decrease in passive, active, and rigor stiffness compared with rescued fibers, but no significant decrease in isometric tension generation was observed. Muscle ultrastructure of Mlp84B-null muscle fibers is grossly normal; however, the null fibers have a slight decrease, 11%, in thick filament number per unit cross-sectional area. Our data indicate that MLP contributes to muscle stiffness and is necessary for maximum work and power generation.

Alternative Versions of the Myosin Relay Domain Differentially Respond to Load to Influence Drosophila Muscle Kinetics

Yang, Chaoxing; Ramanath, Seemanti; Kronert, William A.; Bernstein, Sanford I.; Maughan, David W.; Swank, Douglas M.
Fonte: The Biophysical Society Publicador: The Biophysical Society
Tipo: Artigo de Revista Científica
EN
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36.14%
We measured the influence of alternative versions of the Drosophila melanogaster myosin heavy chain relay domain on muscle mechanical properties. We exchanged relay domain regions (encoded by alternative versions of exon 9) between an embryonic (EMB) isoform and the indirect flight muscle isoform (IFI) of myosin. Previously, we observed no effect of exchanging the EMB relay domain region into the flight muscle isoform (IFI-9b) on in vitro actin motility velocity or solution ATPase measurements compared to IFI. However, in indirect flight muscle fibers, IFI-9b exhibited decreased maximum power generation (Pmax) and optimal frequency of power generation (fmax) to 70% and 83% of IFI fiber values. The decrease in muscle performance reduced the flight ability and wing-beat frequency of IFI-9b Drosophila compared to IFI Drosophila. Previously, we found that exchanging the flight muscle specific relay domain into the EMB isoform (EMB-9a) prevented actin movement in the in vitro motility assay compared to EMB, which does support actin movement. However, in indirect flight muscle fibers EMB-9a was a highly effective motor, increasing Pmax and fmax 2.5-fold and 1.4-fold, respectively, compared to fibers expressing EMB. We propose that the oscillatory load EMB-9a experiences in the muscle fiber reduces a high activation energy barrier between two strongly bound states of the cross-bridge cycle...

Muscle mass, structural and functional investigations of senescence-accelerated mouse P8 (SAMP8)

Guo, An Yun; Leung, Kwok Sui; Siu, Parco Ming Fai; Qin, Jiang Hui; Chow, Simon Kwoon Ho; Qin, Ling; Li, Chi Yu; Cheung, Wing Hoi
Fonte: Japanese Association for Laboratory Animal Science Publicador: Japanese Association for Laboratory Animal Science
Tipo: Artigo de Revista Científica
EN
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36.12%
Sarcopenia is an age-related systemic syndrome with progressive deterioration in skeletal muscle functions and loss in mass. Although the senescence-accelerated mouse P8 (SAMP8) was reported valid for muscular ageing research, there was no report on the details such as sarcopenia onset time. Therefore, this study was to investigate the change of muscle mass, structure and functions during the development of sarcopenia. Besides the average life span, muscle mass, structural and functional measurements were also studied. Male SAMP8 animals were examined at month 6, 7, 8, 9, and 10, in which the right gastrocnemius was isolated and tested for ex vivo contractile properties and fatigability while the contralateral one was harvested for muscle fiber cross-sectional area (FCSA) and typing assessments. Results showed that the peak of muscle mass appeared at month 7 and the onset of contractility decline was observed from month 8. Compared with month 8, most of the functional parameters at month 10 decreased significantly. Structurally, muscle fiber type IIA made up the largest proportion of the gastrocnemius, and the fiber size was found to peak at month 8. Based on the altered muscle mass, structural and functional outcomes, it was concluded that the onset of sarcopenia in SAMP8 animals was at month 8. SAMP8 animals at month 8 should be at pre-sarcopenia stage while month 10 at sarcopenia stage. It is confirmed that SAMP8 mouse can be used in sarcopenia research with established time line in this study.

Stroke and glide of wing-propelled divers: deep diving seabirds adjust surge frequency to buoyancy change with depth.

Watanuki, Yutaka; Niizuma, Yasuaki; Gabrielsen, Geir Wing; Sato, Katsufumi; Naito, Yasuhiko
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 07/03/2003 EN
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36.11%
In order to increase locomotor efficiency, breath-holding divers are expected to adjust their forward thrusts in relation to changes of buoyancy with depth. Wing propulsion during deep diving by Brünnich's guillemots (Uria lomvia) was measured in the wild by high-speed (32 Hz) sampling of surge (tail-to-head) and heave (ventral-to-dorsal) accelerations with bird-borne data loggers. At the start of descent, the birds produced frequent surges (3.2 Hz) during both the upstroke and the downstroke against buoyancy to attain a mean speed of 1.2-1.8 m s(-1) that was close to the expected optimal swim speed. As they descended deeper, the birds decreased the frequency of surges to 2.4 Hz, relaying only on the downstroke. During their ascent, they stopped stroking at 18 m depth, after which the swim speed increased to 2.3 m s(-1), possibly because of increasing buoyancy as air volumes expanded. This smooth change of surge frequency was achieved while maintaining a constant stroke duration (0.4-0.5 s), presumably allowing efficient muscle contraction.

Observations préliminaires sur la structure de la strie Z dans le muscle alaire de l'abeille; Preliminary observations on the structure of the Z lines in the wing muscle of the bee

Garamvölgyi, Nicolas
Fonte: INRA - Instituto Nacional de Investigação Agronômica da França Publicador: INRA - Instituto Nacional de Investigação Agronômica da França
Tipo: Journal Article-postprint
FR; FRENCH
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L'étude au microscope électronique du muscle alaire de l'Abeille Apis mellifica nous a permis d'apporter certaines précisions sur l'ultrastucture de ce muscle. En particulier nous avons pu étudier les connexions existant entre les filaments primaires et la strie Z, en l'absence de bande I. Les muscles ont été fixés au tétroxyde d'osmium, déshydratés à l'alcool éthylique et inclus dans l'araldite selon la technique de Glauert et Glauert (11). Les coupes minces ont été effectuées au microtome Porter Blum et colorées à l'acide phosphotungstique en solution alcoolique durant 5 mn. Les clichés ont été pris au microscope RCA EMU-3C.

Estudo controlado da força muscular e equilíbrio de idosas participantes da ala das baianas de escola de samba ; Controlled study that analyze the postural balance, muscle strength of women who casting in the carnaval parades

Serra, Marcos Mauricio
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 17/09/2015 PT
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36.08%
A dança possibilita a aquisição de habilidades e auxilia na melhora da capacidade motora, permitindo movimentos mais complexos. O objetivo deste trabalho foi analisar o equilíbrio postural e a força muscular de mulheres idosas que participam de desfiles no carnaval. Métodos: Para a realização do estudo foram recrutadas 110 mulheres, com média de idade de 67,4 (5,9) anos, divididas em dois grupos. Um grupo de idosas participantes dos desfiles de carnaval na \"Ala das Baianas\" (Gr- Baianas) e um grupo controle que não realiza tal atividade (Gr-Controle). Foram avaliadas as características sociodemográficas; clínicas; atividade física; psicocognitivas: utilizando a Escala de Depressão Geriátrica (EDG), Mini-Exame do Estado Mental de Folstein(MEEM); equilíbrio postural dinâmico: Time up & Go Test com e sem dupla tarefa; força muscular de flexores e extensores de joelho utilizando o dinamômetro isocinético; força de preensão palmar e avaliação do equilíbrio postural por meio de uma plataforma de força nas seguintes condições: olhos abertos e olhos fechados. Resultados: Nas condições sócio-demográficas os grupos foram diferentes no item socioeconômico. Não houve diferenças significantes na avaliação psico-cognitiva...