Journal articles: 'Fast-to-slow transformation'

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Jarvis, Jonathan C., Thomas Mokrusch, Martin M. N. Kwende, Hazel Sutherland, and Stanley Salmons. "Fast-to-slow transformation in stimulated rat muscle." Muscle & Nerve 19, no. 11 (1996): 1469–75. http://dx.doi.org/10.1002/(sici)1097-4598(199611)19:11<1469::aid-mus11>3.0.co;2-o.

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Zhang, Shurun, Xiaoling Chen, Zhiqing Huang, et al. "Leucine promotes porcine myofibre type transformation from fast-twitch to slow-twitch through the protein kinase B (Akt)/forkhead box 1 signalling pathway and microRNA-27a." British Journal of Nutrition 121, no. 1 (2018): 1–8. http://dx.doi.org/10.1017/s000711451800301x.

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AbstractMuscle fibre types can transform from slow-twitch (slow myosin heavy chain (MyHC)) to fast-twitch (fast MyHC) or vice versa. Leucine plays a vital effect in the development of skeletal muscle. However, the role of leucine in porcine myofibre type transformation and its mechanism are still unclear. In this study, effects of leucine and microRNA-27a (miR-27a) on the transformation of porcine myofibre type were investigatedin vitro. We found that leucine increased slow MyHC protein level and decreased fast MyHC protein level, increased the levels of phospho-protein kinase B (Akt)/Akt and phospho-forkhead box 1 (FoxO1)/FoxO1 and decreased the FoxO1 protein level. However, blocking the Akt/FoxO1 signalling pathway by wortmannin attenuated the role of leucine in porcine myofibre type transformation. Over-expression of miR-27a decreased slow MyHC protein level and increased fast MyHC protein level, whereas inhibition of miR-27a had an opposite effect. We also found that expression of miR-27a was down-regulated following leucine treatment. Moreover, over-expression of miR-27a repressed transformation from fast MyHC to slow MyHC caused by leucine, suggesting that miR-27a is interdicted by leucine and then contributes to porcine muscle fibre type transformation. Our finding provided the first evidence that leucine promotes porcine myofibre type transformation from fast MyHC to slow MyHC via the Akt/FoxO1 signalling pathway and miR-27a.

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Windisch, A., K. Gundersen, M. J. Szabolcs, H. Gruber, and T. Lømo. "Fast to slow transformation of denervated and electrically stimulated rat muscle." Journal of Physiology 510, no. 2 (1998): 623–32. http://dx.doi.org/10.1111/j.1469-7793.1998.623bk.x.

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Mu, Xiaodong, Lisa D. Brown, Yewei Liu, and Martin F. Schneider. "Roles of the calcineurin and CaMK signaling pathways in fast-to-slow fiber type transformation of cultured adult mouse skeletal muscle fibers." Physiological Genomics 30, no. 3 (2007): 300–312. http://dx.doi.org/10.1152/physiolgenomics.00286.2006.

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Two Ca2+-dependent signaling pathways, mediated by the Ca2+-activated phosphatase calcineurin and by the Ca2+-activated kinase Ca2+/calmodulin-dependent kinase (CaMK), are both believed to function in fast-to-slow skeletal muscle fiber type transformation, but questions about the relative importance of the two pathways still remain. Here, the differential gene expression during fast-to-slow fiber type transformation was studied using cultured adult flexor digitorum brevis (FDB) fibers and a custom minimicroarray system containing 21 fiber type-specific marker genes. After 3 days of culture, unstimulated fibers showed a generally slower gene expression profile; 3 days of electric field stimulation of cultured FDB fibers with a slow fiber-type pattern transformed the fibers to an even slower gene expression profile. Unstimulated FDB fibers overexpressing constitutively active calcineurin featured a slower gene expression profile, except four genes, indicating that transformation occurred, but was incomplete with activation of the calcineurin pathway alone. In both unstimulated FDB fibers and slow-type electrically stimulated FDB fibers, blocking of CaMK pathway with KN93 generated a faster gene expression profile compared with the negative control KN92, indicating that CaMK pathway functions during the transformation induced by both unstimulated culturing and slow fiber-type electrical stimulation. Moreover, neither the calcineurin nor the CaMK pathway alone could maximally activate the transformation, and coordination of the two pathways is required to accomplish a complete fast-to-slow fiber type transformation.

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Shenkman, B. S. "From Slow to Fast: Hypogravity-Induced Remodeling of Muscle Fiber Myosin Phenotype." Acta Naturae 8, no. 4 (2016): 47–59. http://dx.doi.org/10.32607/20758251-2016-8-4-47-59.

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Skeletal muscle consists of different fiber types arranged in a mosaic pattern. These fiber types are characterized by specific functional properties. Slow-type fibers demonstrate a high level of fatigue resistance and prolonged contraction duration, but decreased maximum contraction force and velocity. Fast-type fibers demonstrate a high contraction force and velocity, but profound fatigability. During the last decades, it has been discovered that all these properties are determined by the predominance of slow or fast myosin-heavy-chain (MyHC) isoforms. It was observed that gravitational unloading during space missions and simulated microgravity in ground-based experiments leads to the transformation of some slow-twitch muscle fibers into fast-twitch ones due to changes in the patterns of MyHC gene expression in the postural soleus muscle. The present review covers the facts and mechanistic speculations regarding myosin phenotype remodeling under conditions of gravitational unloading. The review considers the neuronal mechanisms of muscle fiber control and molecular mechanisms of regulation of myosin gene expression, such as inhibition of the calcineurin/NFATc1 signaling pathway, epigenomic changes, and the behavior of specific microRNAs. In the final portion of the review, we discuss the adaptive role of myosin phenotype transformations.

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Li, Xianghong, Jingyu Hou, and Yongjun Shen. "Slow-fast effect and generation mechanism of brusselator based on coordinate transformation." Open Physics 14, no. 1 (2016): 261–68. http://dx.doi.org/10.1515/phys-2016-0032.

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AbstractThe Brusselator with different time scales, which behaves in the classical slow-fast effect, is investigated, and is characterized by the coupling of the quiescent and spiking states. In order to reveal the generation mechanism by using the slow-fast analysis method, the coordinate transformation is introduced into the classical Brusselator, so that the transformed system can be divided into the fast and slow subsystems. Furthermore, the stability condition and bifurcation phenomenon of the fast subsystem are analyzed, and the attraction domains of different equilibria are presented by theoretical analysis and numerical simulation respectively. Based on the transformed system, it could be found that the generation mechanism between the quiescent and spiking states is Fold bifurcation and change of the attraction domain of the fast subsystem. The results may also be helpful to the similar system with multiple time scales.

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Meißner, Joachim D., Gerolf Gros, Renate J. Scheibe, Michael Scholz, and Hans‐Peter Kubis. "Calcineurin regulates slow myosin, but not fast myosin or metabolic enzymes, during fast‐to‐slow transformation in rabbit skeletal muscle cell culture." Journal of Physiology 533, no. 1 (2001): 215–26. http://dx.doi.org/10.1111/j.1469-7793.2001.0215b.x.

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Reiser, Peter J., William O. Kline, and Pal L. Vaghy. "Induction of neuronal type nitric oxide synthase in skeletal muscle by chronic electrical stimulation in vivo." Journal of Applied Physiology 82, no. 4 (1997): 1250–55. http://dx.doi.org/10.1152/jappl.1997.82.4.1250.

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Reiser, Peter J., William O. Kline, and Pal L. Vaghy.Induction of neuronal type nitric oxide synthase in skeletal muscle by chronic electrical stimulation in vivo. J. Appl. Physiol. 82(4): 1250–1255, 1997.—Fast-twitch skeletal muscles contain more neuronal-type nitric oxide synthase (nNOS) than slow-twitch muscles because nNOS is present only in fast (type II) muscle fibers. Chronic in vivo electrical stimulation of tibialis anterior and extensor digitorum longus muscles of rabbits was used as a method of inducing fast-to-slow fiber type transformation. We have studied whether an increase in muscle contractile activity induced by electrical stimulation alters nNOS expression, and if so, whether the nNOS expression decreases to the levels present in slow muscles. Changes in the expression of myosin heavy chain isoforms and maximum velocity of shortening of skinned fibers indicated characteristic fast-to-slow fiber type transformation after 3 wk of stimulation. At the same time, activity of NOS doubled in the stimulated muscles, and this correlated with an increase in the expression of nNOS shown by immunoblot analysis. These data suggest that nNOS expression in skeletal muscle is regulated by muscle activity and that this regulation does not necessarily follow the fast-twitch and slow-twitch pattern during the dynamic phase of phenotype transformation.

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Fournier le Ray, C., D. Renaud, and G. H. Le Douarin. "Change in motor neurone activity modifies the differentiation of a slow muscle in chick embryo." Development 106, no. 2 (1989): 295–302. http://dx.doi.org/10.1242/dev.106.2.295.

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Slow-tonic anterior latissimus dorsi (ALD) muscle properties were studied following chronic spinal cord stimulation in chick embryo. Stimulation at a fast rhythm was applied from day 7, 8 or 10 of development until the end of embryonic life. When stimulation was applied from day 7 up to day 18 of development, ALD muscle exhibited at day 18 a large decrease in half time to peak of tetanic contraction, a large proportion of fast type II fibres and an increase in fast myosin light chain content as compared to control muscle. When stimulation started at day 8 of development, changes in properties of ALD muscle were reduced when compared to the previous experimental series. Indeed, no fast type II fibres were observed within the muscle, even when stimulation was prolongated until the 20th day of embryonic development. In addition, chronic stimulation at a fast rhythm initiated at day 10 of development did not modify ALD muscle differentiation. The present results indicate that a fast pattern of motor neurone activity can induce some slow-to-fast transformations of ALD muscle fibres. However, after the first week of embryonic life, ALD myotubes appeared refractory to these transformations. The possible mechanisms responsible for the transformation of slow myotubes and for their further loss of plasticity are discussed.

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Sreter, F. A., J. R. Lopez, L. Alamo, K. Mabuchi, and J. Gergely. "Changes in intracellular ionized Ca concentration associated with muscle fiber type transformation." American Journal of Physiology-Cell Physiology 253, no. 2 (1987): C296—C300. http://dx.doi.org/10.1152/ajpcell.1987.253.2.c296.

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Since increased muscle activity, which results in fast-slow fiber transformation, is associated with increases in sarcoplasmic Ca2+ concentration ([Ca2+]i), it seemed of interest to study the level of [Ca2+] after cessation of stimulation in fibers of the extensor digitorum longus muscle chronically stimulated (8 Hz). [Ca2+]i was measured in individual fibers with a Ca2+-sensitive electrode after subtracting the membrane potential, measured simultaneously from the potential of the Ca2+ electrode. During the first 14 days of stimulation, [Ca2+]i increased from approximately 0.1 to 0.5 microM and declined in approximately 3 wk to a value slightly higher than the initial one. The rise and decline of [Ca2+]i was preceded by a transient increase in total calcium. If stimulation was terminated after 7-8 wk when an essentially complete fast-to-slow transformation had taken place, a subsequent rest period led to a reverse slow-to-fast transformation, which was also preceded by a transient increase of [Ca2+]i reaching a peak at day 5 of rest. Unstimulated fast and slow fibers and fully transformed fibers do not differ in their [Ca2+] levels; thus it appears that the transformation process itself is accompanied, particularly in its earlier stages, by elevated [Ca2+]i levels. Elucidation of the relation between changes in Ca2+ and changes in gene expression will require further work.

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Somasekhar, Thummala, Ruth H. Nordlander, and Peter J. Reiser. "Alterations in neuromuscular junction morphology during fast-to-slow transformation of rabbit skeletal muscles." Journal of Neurocytology 25, no. 1 (1996): 315–31. http://dx.doi.org/10.1007/bf02284805.

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12

Levine, Sanford, Taitan Nguyen, Michael Friscia, et al. "Parasternal intercostal muscle remodeling in severe chronic obstructive pulmonary disease." Journal of Applied Physiology 101, no. 5 (2006): 1297–302. http://dx.doi.org/10.1152/japplphysiol.01607.2005.

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Studies in experimental animals indicate that chronic increases in neural drive to limb muscles elicit a fast-to-slow transformation of fiber-type proportions and myofibrillar proteins. Since neural drive to the parasternal intercostal muscles (parasternals) is chronically increased in patients with severe chronic obstructive pulmonary diseases (COPDs), we carried out the present study to test the hypothesis that the parasternals of COPD patients exhibit an increase in the proportions of both slow fibers and slow myosin heavy chains (MHCs). Accordingly, we obtained full thickness parasternal muscle biopsies from the third interspace of seven COPD patients (mean ± SE age: 59 ± 4 yr) and seven age-matched controls (AMCs). Fiber typing was done by immunohistochemistry, and MHC proportions were determined by SDS-PAGE followed by densitometry. COPD patients exhibited higher proportions of slow fibers than AMCs (73 ± 4 vs. 51 ± 3%; P < 0.01). Additionally, COPD patients exhibited higher proportions of slow MHC than AMCs (56 ± 4 vs. 46 ± 4%, P < 0.04). We conclude that the parasternal muscles of patients with severe COPD exhibit a fast-to-slow transformation in both fiber-type and MHC proportions. Previous workers have demonstrated that remodeling of the external intercostals, another rib cage inspiratory muscle, elicited by severe COPD is characterized by a slow-to-fast transformation in both fiber types and MHC isoform proportions. The physiological significance of this difference in remodeling between these two inspiratory rib cage muscles remains to be elucidated.

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Laurie-Ahlberg, Cathy C., and Lynn F. Stam. "Use of P-Element-Mediated Transformation to Identify the Molecular Basis of Naturally Occurring Variants Affecting Adh Expression in Drosophila melanogaster." Genetics 115, no. 1 (1987): 129–40. http://dx.doi.org/10.1093/genetics/115.1.129.

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ABSTRACT The purpose of the work reported here is to identify the molecular basis of the difference in level of expression between the polymorphic Slow and Fast alcohol dehydrogenase (Adh) alleles in Drosophila melanogaster . Previous studies have shown that Fast lines typically have a two- to threefold higher activity level than Slow lines and they also have a substantially higher level of ADH-protein (estimated immunologically). The results of a restriction fragment length polymorphism study in relation to ADH activity variation had previously suggested that the difference in Adh expression between allozymes might not be due entirely to the amino acid replacement substitution, but could be due in part to linkage disequilibrium with a regulatory site polymorphism. Here we describe an approach that makes use of P-element-mediated transformation in order to identify the nucleotide substitution(s) responsible for this difference in ADH level. This approach consists of generating recombinants in vitro between Adh region clones derived from a typical Slow/Fast pair of alleles and then testing for the effects of particular restriction fragments on expression in vivo by transformation. Using this approach, the effect on both ADH activity and ADH-protein level clearly maps to a 2.3-kb restriction fragment that includes all of the Adh coding sequence and some intron and 3' flanking sequence, but excludes all of the 5' flanking sequence of the distal (adult) transcriptional unit. Comparison of Kreitman's DNA sequences for this fragment from several Slow and Fast alleles showing the typical difference in activity level shows that only three nucleotide substitutions distinguish all Fast from all Slow alleles. Thus, it is likely that one or more of these substitutions causes the major difference in Adh expression between allozymic classes. One of these substitutions is, of course, the Slow/Fast amino acid replacement substitution (at 1490) while the other two are nearby third position silent substitutions (at 1443 and 1527). A quantiative analysis of variation among transformant stocks shows that the P-element transformation approach can be used to localize even relatively small effects on gene expression (on the order of 20%).

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Gregory, P., R. B. Low, and W. S. Stirewalt. "Changes in skeletal-muscle myosin isoenzymes with hypertrophy and exercise." Biochemical Journal 238, no. 1 (1986): 55–63. http://dx.doi.org/10.1042/bj2380055.

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The patterns of myosin isoenzymes in fast- and slow-twitch muscles of the rat hindlimb were studied, by pyrophosphate/polyacrylamide-gel electrophoresis, with hypertrophy (induced by synergist removal) and with spontaneous running exercise of 4 and 11 weeks duration. At 11 weeks, changes with hypertrophy in the slow-twitch soleus, composed of greater than 95% SM2 (slow myosin 2) in normal muscles, were minor, and consisted of an increase in the SM1 and SM1′, and a loss of intermediate myosin (IM), an isoenzyme characteristic of Type IIa fibres [Fitzsimons & Hoh (1983) J. Physiol. (London) 343, 539-550]. The changes were dramatic, however, in the fast-twitch plantaris muscle. There was a 3-fold increase in the proportion of SM. In addition, IM became the predominant isoenzyme in the profile of hypertrophied plantaris by 4 weeks. These increases were balanced by decreases in the proportion of FM2 (fast myosin 2), with FM1 completely absent from the profile at 11 weeks. The changes in the plantaris with exercise were similar in direction but not as extensive as those with hypertrophy, and FM1 remained present at control levels throughout the study. When hypertrophy and exercise were combined, the increase in slow myosin was equal to the sum of the increases with each treatment alone. Changes at 4 weeks were intermediate between those of control and 11-week muscles. Peptide mapping of individual myosin isoenzymes showed that the heavy chains of IM were different from either fast or slow heavy chains. Furthermore, IM was found to be composed of a mixture of fast and slow light chains. These changes suggest that a transformation of myosin from fast to slow isoforms was in progress in the plantaris in response to hypertrophy, via a Type-IIa-myosin (IM) intermediate stage, a phenomenon similar to that occurring in chronically stimulated fast muscles during fast-to-slow transformation [Brown, Salmons & Whalen (1983) J. Biol. Chem. 258, 14686-14692].

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BRIK, H., and A. SHAINBERG. "Transformation of heart cells in vitro from slow to fast twitch muscle by thyroid hormones." Journal of Molecular and Cellular Cardiology 20, no. 2 (1988): IV. http://dx.doi.org/10.1016/s0022-2828(88)80043-9.

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Kopecká, Kateřina, Gisela Zacharova, Vika Smerdu, and Tomáš Soukup. "Slow to fast muscle transformation following heterochronous isotransplantation is influenced by host thyroid hormone status." Histochemistry and Cell Biology 142, no. 6 (2014): 677–84. http://dx.doi.org/10.1007/s00418-014-1247-5.

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Sultan, Karim R., Bernd T. Dittrich, Elmi Leisner, Nina Paul, and Dirk Pette. "Fiber type-specific expression of major proteolytic systems in fast- to slow-transforming rabbit muscle." American Journal of Physiology-Cell Physiology 280, no. 2 (2001): C239—C247. http://dx.doi.org/10.1152/ajpcell.2001.280.2.c239.

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The present study investigates the role of two major proteolytic systems in transforming rabbit and rat muscles. The fast-to-slow transformation of rabbit muscle by chronic low-frequency stimulation (CLFS) induces fast-to-slow transitions of intact, mature fibers and replacement of degenerating fibers by newly formed slow fibers. Ubiquitination, an indicator of the ATP-dependent proteasome system, and calpain activity were measured in homogenates of control and stimulated extensor digitorum longus muscles. Calpain activity increased similarly (∼2-fold) in stimulated rat and rabbit muscles. CLFS had no effect on protein ubiquitination in rat muscle but led to elevations in ubiquitin protein conjugates in rabbit muscle. Immunohistochemistry was used to study the distribution of μ-calpain and m-calpain and of ubiquitinated proteins in myosin heavy chain-based fiber types. The findings suggest that both proteolytic systems are involved in fiber transformation and replacement. Transforming mature fibers displayed increases in μ-calpain and accumulation of ubiquitin protein conjugates. The majority of these fibers were identified as type IIA. Enhanced ubiquitination was also observed in degenerating and necrotic fibers. Such fibers additionally displayed elevated m-calpain levels. Conversely, p94, the skeletal muscle-specific calpain, decayed rapidly after stimulation onset and was hardly detectable after 4 days of CLFS.

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Kubis, Hans-Peter, Nina Hanke, Renate J. Scheibe, Joachim D. Meissner, and Gerolf Gros. "Ca2+ transients activate calcineurin/NFATc1 and initiate fast-to-slow transformation in a primary skeletal muscle culture." American Journal of Physiology-Cell Physiology 285, no. 1 (2003): C56—C63. http://dx.doi.org/10.1152/ajpcell.00377.2002.

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The calcineurin-mediated signal transduction via nuclear factor of activated T cells (NFATc1) is involved in upregulating slow myosin heavy chain (MHC) gene expression during fast-to-slow transformation of skeletal muscle cells. This study aims to investigate the Ca2+ signal necessary to activate the calcineurin-NFATc1 cascade in skeletal muscle. Electrostimulation of primary myocytes from rabbit for 24 h induced a distinct fast-to-slow transformation at the MHC mRNA level and a full activation of the calcineurin-NFATc1 pathway, although resting Ca2+ concentration ([Ca2+]i) remained unaltered at 70 nM. During activation, the calcium transients of these myocytes reach a peak concentration of ∼500 nM. Although 70 nM [Ca2+]i does not activate calcineurin-NFAT, we show by the use of Ca2+ ionophore that the system is fully activated when [Ca2+]i is ≥150 nM in a sustained manner. We conclude that the calcineurin signal transduction pathway and the slow MHC gene in cultured skeletal muscle cells are activated by repetition of the rapid high-amplitude calcium transients that are associated with excitation-contraction coupling rather than by a sustained elevation of resting Ca2+ concentration.

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Chaminade, Cristina, and Filippo Randelli. "The Role of Territorially Embedded Innovation Ecosystems Accelerating Sustainability Transformations: A Case Study of the Transformation to Organic Wine Production in Tuscany (Italy)." Sustainability 12, no. 11 (2020): 4621. http://dx.doi.org/10.3390/su12114621.

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Over the last few years, there has been a growing concern among academics and practitioners about the slow pace in which sustainability transformations unfold. While most socio-technical transformations tend to happen over extended periods, research shows that unless some dramatic changes are introduced, we are risking damaging the critical earth systems that sustain human life. In this context, understanding why and how transformations happen at a much faster pace in certain places than in others is of crucial importance. This paper investigates the rapid transformation of Panzano, from traditional wine production to organically produced wine. Using a combination of document analysis, participant observation, and face to face interviews in Panzano in 2019, this article examines the role of the territorially embedded innovation ecosystems facilitating this fast transformation. The study looks at place based-structural preconditions and different forms of agency at different stages in the transformation. Our findings illustrate that a place-based agency is paramount for accelerating sustainability transformations.

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Cotter, Mary, and Peter Phillips. "Rapid fast to slow fiber transformation in response to chronic stimulation of immobilized muscles of the rabbit." Experimental Neurology 93, no. 3 (1986): 531–45. http://dx.doi.org/10.1016/0014-4886(86)90173-1.

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Gorza, L., K. Gundersen, T. Lømo, S. Schiaffino, and R. H. Westgaard. "Slow-to-fast transformation of denervated soleus muscles by chronic high-frequency stimulation in the rat." Journal of Physiology 402, no. 1 (1988): 627–49. http://dx.doi.org/10.1113/jphysiol.1988.sp017226.

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Baldi, J. C., M. Alvarez, D. L. Horwitz, R. D. Jackson, and W. J. Mysiw. "EARLY ONSET OF ATROPHY AND SLOW TO FAST FIBER TYPE TRANSFORMATION FOLLOWING SPINAL CORD INJURY 859." Medicine &amp Science in Sports &amp Exercise 28, Supplement (1996): 144. http://dx.doi.org/10.1097/00005768-199605001-00857.

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Staron, R. S., W. J. Kraemer, R. S. Hikida, J. Murray, A. C. Fry, and S. E. Gordon. "UNDERESTIMATION OF SLOW-TO-FAST TRANSFORMATION IN RAT SOLEUS MUSCLES FOLLOWING 10 DAYS OF SPACEFLIGHT 165." Medicine &amp Science in Sports &amp Exercise 29, Supplement (1997): 28. http://dx.doi.org/10.1097/00005768-199705001-00165.

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Brunetti, Orazio, Anna M. Barazzoni, Giovannella Della Torre, Paolo Clavenzani, Vito E. Pettorossi, and Ruggero Bortolami. "Partial transformation from fast to slow muscle fibers induced by deafferentation of capsaicin-sensitive muscle afferents." Muscle & Nerve 20, no. 11 (1997): 1404–13. http://dx.doi.org/10.1002/(sici)1097-4598(199711)20:11<1404::aid-mus8>3.0.co;2-e.

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MIRA, CHRISTIAN, and ANDREY SHILNIKOV. "SLOW–FAST DYNAMICS GENERATED BY NONINVERTIBLE PLANE MAPS." International Journal of Bifurcation and Chaos 15, no. 11 (2005): 3509–34. http://dx.doi.org/10.1142/s0218127405014192.

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The present paper focuses on the two time scale dynamics generated by 2D polynomial noninvertible maps T of (Z0 - Z2) and (Z1 - Z3 - Z1) types. This symbolism, specific to noninvertible maps, means that the phase plane is partitioned into zones Zk, where each point possesses the k real rank-one preimages. Of special interest here is the structure of slow and fast motion sets of such maps. The formation mechanism of a stable invariant close curve through the interaction of fast and slow dynamics, as well as its transformation into a canard are studied. A few among the plethora of chaotic attractors and chaotic transients produced by such maps are described as well.

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Nguyen, Taitan, Neal A. Rubinstein, Camasamudram Vijayasarathy, et al. "Effect of chronic obstructive pulmonary disease on calcium pump ATPase expression in human diaphragm." Journal of Applied Physiology 98, no. 6 (2005): 2004–10. http://dx.doi.org/10.1152/japplphysiol.00767.2004.

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We have previously demonstrated that human diaphragm remodeling elicited by severe chronic obstructive pulmonary disease (COPD) is characterized by a fast-to-slow myosin heavy chain isoform transformation. To test the hypothesis that COPD-induced diaphragm remodeling also elicits a fast-to-slow isoform shift in the sarcoendoplasmic reticulum Ca2+ ATPase (SERCA), the other major ATPase in skeletal muscle, we obtained intraoperative biopsies of the costal diaphragm from 10 severe COPD patients and 10 control subjects. We then used isoform-specific monoclonal antibodies to characterize diaphragm fibers with respect to the expression of SERCA isoforms. Compared with control diaphragms, COPD diaphragms exhibited a 63% decrease in fibers expressing only fast SERCA (i.e., SERCA1; P < 0.001), a 190% increase in fibers containing both fast and slow SERCA isoforms ( P < 0.01), and a 19% increase ( P < 0.05) in fibers expressing only the slow SERCA isoform (i.e., SERCA2). Additionally, immunoblot experiments carried out on diaphragm homogenates indicated that COPD diaphragms expressed only one-third the SERCA1 content noted in control diaphragms; in contrast, COPD and control diaphragms did not differ with respect to SERCA2 content. The combination of these histological and immunoblot results is consistent with the hypothesis that diaphragm remodeling elicited by severe COPD is characterized by a fast-to-slow SERCA isoform transformation. Moreover, the combination of these SERCA data and our previously reported myosin heavy chain isoform data (Levine S, Nguyen T, Kaiser LR, Rubinstein NA, Maislin G, Gregory C, Rome LC, Dudley GA, Sieck GC, and Shrager JB. Am J Respir Crit Care Med 168: 706–713, 2003) suggests that diaphragm remodeling elicited by severe COPD should decrease ATP utilization by the diaphragm.

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Chen, Xiaoling, Yafei Guo, Gang Jia, Guangmang Liu, Hua Zhao, and Zhiqing Huang. "Arginine promotes skeletal muscle fiber type transformation from fast-twitch to slow-twitch via Sirt1/AMPK pathway." Journal of Nutritional Biochemistry 61 (November 2018): 155–62. http://dx.doi.org/10.1016/j.jnutbio.2018.08.007.

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Hirabayashi, Miho, Daichi Ijiri, Yasutomi Kamei, Atsushi Tajima, and Yukio Kanai. "Transformation of Skeletal Muscle from Fast- to Slow-Twitch during Acquisition of Cold Tolerance in the Chick." Endocrinology 146, no. 1 (2005): 399–405. http://dx.doi.org/10.1210/en.2004-0723.

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Acevedo, Luz M., Alan Peralta-Ramírez, Ignacio López, et al. "Slow- and fast-twitch hindlimb skeletal muscle phenotypes 12 wk after ⅚ nephrectomy in Wistar rats of both sexes." American Journal of Physiology-Renal Physiology 309, no. 7 (2015): F638—F647. http://dx.doi.org/10.1152/ajprenal.00195.2015.

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This study describes fiber-type adaptations in hindlimb muscles, the interaction of sex, and the role of hypoxia on this response in 12-wk ⅚ nephrectomized rats (Nx). Contractile, metabolic, and morphological features of muscle fiber types were assessed in the slow-twitch soleus and the fast-twitch tibialis cranialis muscles of Nx rats, and compared with sham-operated controls. Rats of both sexes were considered in both groups. A slow-to-fast fiber-type transformation occurred in the tibialis cranialis of Nx rats, particularly in males. This adaptation was accomplished by impaired oxidative capacity and capillarity, increased glycolytic capacity, and no changes in size and nuclear density of muscle fiber types. An oxidative-to-glycolytic metabolic transformation was also found in the soleus muscle of Nx rats. However, a modest fast-to-slow fiber-type transformation, fiber hypertrophy, and nuclear proliferation were observed in soleus muscle fibers of male, but not of female, Nx rats. Serum testosterone levels decreased by 50% in male but not in female Nx rats. Hypoxia-inducible factor-1α protein level decreased by 42% in the tibialis cranialis muscle of male Nx rats. These data demonstrate that 12 wk of Nx induces a muscle-specific adaptive response in which myofibers do not change (or enlarge minimally) in size and nuclear density, but acquire markedly different contractile and metabolic characteristics, which are accompanied by capillary rarefaction. Muscle function and sex play relevant roles in these adaptations.

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Herbort, Oliver. "Where to Grasp a Tool?" Zeitschrift für Psychologie 220, no. 1 (2012): 37–43. http://dx.doi.org/10.1027/2151-2604/a000089.

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Biomechanical and environmental constraints limit body movements and tool use actions. However, in the case of tool use, such constraints can often be overcome by adjusting a tool’s tool transformation to the requirements of the intended tool use action. The research presented here examined whether participants grasped a lever at different positions, thus modifying the lever’s tool transformation, to accommodate speed and accuracy requirements of different tasks. Participants were asked to quickly track a sequence of targets with the lever. If accuracy requirements were high, participants compensated for limits in the accuracy of hand movements by grasping the lever at a position that enabled precise control of the lever. If accuracy requirements were low, participants compensated for limits in hand speed by grasping the lever at a position that enabled fast lever movements with comparatively slow hand movements. This task-dependent grasp selection was only present after participants had practiced the tasks. The data show that in addition to adapting to fixed tool transformations, participants also actively controlled tool transformations to facilitate tool use actions.

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Marinescu, Marilena, James Bouley, Juyu Chueh, Marc Fisher, and Nils Henninger. "Clot Injection Technique Affects Thrombolytic Efficacy in a Rat Embolic Stroke Model: Implications for Translaboratory Collaborations." Journal of Cerebral Blood Flow & Metabolism 34, no. 4 (2014): 677–82. http://dx.doi.org/10.1038/jcbfm.2014.1.

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Current recommendations encourage the use of embolic stroke (ES) models and replication of results across laboratories in preclinical research. Since such endeavors employ different surgeons, we sought to ascertain the impact of injection technique on outcome and response to thrombolysis in an ES model. Embolic stroke was induced in Male Wistar Kyoto rats ( n=166) by a fast or a slow clot injection (CI) technique. Saline or recombinant tissue plasminogen activator (rtPA) was given at 1 hour after stroke. Flow rate curves were assessed in 24 animals. Cerebral perfusion was assessed using laser Doppler flowmetry. Edema corrected infarct volume, hemispheric swelling, hemorrhagic transformation, and neurologic outcome were assessed at 24 hours after stroke. Clot burden was estimated in a subset of animals ( n=40). Slow CI resulted in significantly smaller infarct volumes ( P=0.024) and better neurologic outcomes ( P=0.01) compared with fast CI at 24 hours. Unexpectedly, rtPA treatment attenuated infarct size in fast ( P<0.001) but not in slow CI experiments ( P=0.382), possibly related to reperfusion injury as indicated by greater hemorrhagic transformation ( P<0.001) and hemispheric swelling ( P<0.05). Outcome and response to thrombolysis after ES are operator dependent, which needs to be considered when comparing results obtained from different laboratories.

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Boudreau-Lariviere, C., V. Gisiger, R. N. Michel, D. A. Hubatsch, and B. J. Jasmin. "Fast and slow skeletal muscles express a common basic profile of acetylcholinesterase molecular forms." American Journal of Physiology-Cell Physiology 272, no. 1 (1997): C68—C76. http://dx.doi.org/10.1152/ajpcell.1997.272.1.c68.

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Recent evidence suggests that the high content of acetylcholinesterase (AChE) globular form G4, characteristic of fast muscles, is controlled by phasic high-frequency activity performed by these muscles. This indicates that inactive, though still innervated, fast muscles should be devoid of their characteristic G4 pool. Accordingly, in the absence of phasic activity, both fast and slow muscles should exhibit a common basic profile of AChE molecular forms of the slow type. We first tested this hypothesis by examining the AChE content in cultures of myotubes obtained from the fusion of satellite cells originating from fast and slow muscles. These two cell populations produced AChE molecular-form profiles of the slow type characterized by modest levels of G4 together with an increased proportion of the asymmetric forms A8 relative to A12. Second, we determined the impact of muscle paralysis on the specific content of AChE molecular forms of adult rat fast and slow muscles. Complete paralysis of hindlimb muscles was achieved by chronic superfusion of tetrodotoxin (TTX) onto the sciatic nerve. Ten days after TTX inactivation, the distributions of AChE molecular forms of both fast extensor digitorum longus (EDL) and plantaris muscles were transformed into ones resembling the slow soleus, the latter showing no significant modifications in its AChE profile. Finally, we investigated the impact of nerve-mediated phasic high-frequency stimulation of TTX-inactivated fast and slow muscles on the content of AChE molecular forms. This stimulation produced a profile of AChE molecular forms similar to that observed in control EDL muscles, indicating that phasic activation counteracted the TTX-induced transformation in the distribution of AChE molecular forms in fast EDL muscles. Together, these results are consistent with the proposal that adult fast muscles constitutively express a basic profile of AChE molecular forms of the type displayed by slow muscles, onto which varying levels of G4 are added according to the amount of phasic activity performed by the muscles.

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33

Huchet-Cadiou, C., V. Bonnet, W. Meme, and C. Leoty. "Hypogravity increases cyclopiazonic acid sensitivity of rat soleus muscle." Journal of Applied Physiology 80, no. 4 (1996): 1100–1104. http://dx.doi.org/10.1152/jappl.1996.80.4.1100.

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The functional capacity of skeletal muscle sarcoplasmic reticulum was explored in slow rat soleus muscle after 21 days of hindlimb suspension. The sarcoplasmic reticulum function was assessed in intact and saponin-skinned fibers by using cyclopiazonic acid, a specific Ca(2+)-adenosinetriphosphatase inhibitor. After hindlimb unweighting, the sensitivity to cyclopiazonic acid of intact and skinned soleus fibers becomes similar to that found in fast-twitch muscles. This change could be related to the expression of fast Ca2(+)-adenosinetriphosphatase-pump protein in unloaded soleus muscles and agrees with a transformation of soleus muscle from slow- to fast-twitch type. These results also indicate that specific pharmacological tools, like cyclopiazonic acid, could be used to analyze subcellular functional changes due to hindlimb unweighting.

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34

Jacobs-El, J., W. Ashley, and B. Russell. "IIx and slow myosin expression follow mitochondrial increases in transforming muscle fibers." American Journal of Physiology-Cell Physiology 265, no. 1 (1993): C79—C84. http://dx.doi.org/10.1152/ajpcell.1993.265.1.c79.

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Metabolic profile and contractile isoform expression commonly define classic fiber types in skeletal muscle. Little is known about how metabolic requirements determine expression of fast IIx and slow myosin isoforms in muscles undergoing fiber type conversion. Tibialis anterior muscles from female New Zealand White rabbits were stimulated continuously at 10 Hz for 4-21 days. Quantitative fiber analysis was made for oxidative potential by histochemistry and for fast IIx and slow myosin mRNA content by in situ hybridization. In control muscle we found 3 +/- 0.27% fibers coexpress both fast IIx and slow myosin mRNA and so were not assignable to a classic fiber type. After stimulation, increase in fiber oxidative potential was detectable by 4 days and preceded IIx mRNA increases on a fiber-by-fiber basis. Slow myosin transcripts were detected by 7 days in fibers with higher oxidative levels. Coexpression of IIx and slow transcripts peaked at 22 +/- 2.5% of fibers by 7 days. IIx then declined, leaving slow myosin expressed in 62 +/- 0.45% of fibers by 3 wk. We conclude that during fiber type transformation individual fibers can transcribe two myosin mRNAs synchronously. Metabolic demand precedes and may be linked to IIx and slow myosin isoform expression.

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35

KRAVETC, P., D. RACHINSKII, and A. VLADIMIROV. "Periodic pulsating dynamics of slow–fast delayed systems with a period close to the delay." European Journal of Applied Mathematics 30, no. 1 (2017): 39–62. http://dx.doi.org/10.1017/s0956792517000377.

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We consider slow–fast delayed systems and discuss pulsating periodic solutions, which are characterised by specific properties that (a) the period of the periodic solution is close to the delay, and (b) these solutions are formed close to a bifurcation threshold. Such solutions were previously found in models of mode-locked lasers. Through a case study of population models, this work demonstrates the existence of similar solutions for a rather wide class of delayed systems. The periodic dynamics originates from the Hopf bifurcation on the positive equilibrium. We show that the continuous transformation of the periodic orbit to the pulsating regime is simultaneous with multiple secondary almost resonant Hopf bifurcations, which the equilibrium undergoes over a short interval of parameter values. We derive asymptotic approximations for the pulsating periodic solution and consider scaling of the solution and its period with the small parameter that measures the ratio of the time scales. The role of competition for the realisation of the bifurcation scenario is highlighted.

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36

Midrio, M., D. Danieli-Betto, A. Megighian, C. Velussi, C. Catani, and U. Carraro. "Slow-to-fast transformation of denervated soleus muscle of the rat, in the presence of an antifibrillatory drug." Pfl�gers Archiv European Journal of Physiology 420, no. 5-6 (1992): 446–50. http://dx.doi.org/10.1007/bf00374618.

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37

Wen, Wanxue, Xiaoling Chen, Zhiqing Huang, et al. "Lycopene promotes a fast-to-slow fiber type transformation through Akt/FoxO1 signaling pathway and miR-22-3p." Journal of Functional Foods 80 (May 2021): 104430. http://dx.doi.org/10.1016/j.jff.2021.104430.

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38

Sharlo, Kristina A., Inna I. Paramonova, Irina D. Lvova, et al. "Plantar Mechanical Stimulation Maintains Slow Myosin Expression in Disused Rat Soleus Muscle via NO-Dependent Signaling." International Journal of Molecular Sciences 22, no. 3 (2021): 1372. http://dx.doi.org/10.3390/ijms22031372.

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It was observed that gravitational unloading during space missions and simulated microgravity in ground-based studies leads to both transformation of slow-twitch muscle fibers into fast-twitch fibers and to the elimination of support afferentation, leading to the “switching-off” of postural muscle motor units electrical activity. In recent years, plantar mechanical stimulation (PMS) has been found to maintain the neuromuscular activity of the hindlimb muscles. Nitric oxide (NO) was shown to be one of the mediators of muscle fiber activity, which can also promote slow-type myosin expression. We hypothesized that applying PMS during rat hindlimb unloading would lead to NO production upregulation and prevention of the unloading-induced slow-to-fast fiber-type shift in rat soleus muscles. To test this hypothesis, Wistar rats were hindlimb suspended and subjected to daily PMS, and one group of PMS-subjected animals was also treated with nitric oxide synthase inhibitor (L-NAME). We discovered that PMS led to sustained NO level in soleus muscles of the suspended animals, and NOS inhibitor administration blocked this effect, as well as the positive effects of PMS on myosin I and IIa mRNA transcription and slow-to-fast fiber-type ratio during rat hindlimb unloading. The results of the study indicate that NOS activity is necessary for the PMS-mediated prevention of slow-to-fast fiber-type shift and myosin I and IIa mRNA transcription decreases during rat hindlimb unloading.

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39

Pette, D., and S. Dusterhoft. "Altered gene expression in fast-twitch muscle induced by chronic low-frequency stimulation." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 262, no. 3 (1992): R333—R338. http://dx.doi.org/10.1152/ajpregu.1992.262.3.r333.

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Increased neuromuscular activity via chronic low-frequency stimulation induces multiple fast-to-slow transitions in phenotypic properties that ultimately lead to fiber type conversions in the fast-twitch muscle of small mammals. Most of these alterations occur in an ordered sequence and result from the sequentially altered expression of myofibrillar and other protein isoforms. These changes relate to altered levels of specific mRNAs, followed by alterations in protein synthesis. As shown by the exchange of myosin heavy chain isoforms, protein degradation may be an additional control factor involved in the rearrangement of the myofibrillar apparatus. The degree of the various fast-to-slow transitions is species dependent and may be related to differences in thyroid hormone levels. It is suggested that the drastically and persistently depressed phosphorylation potential of the ATP system possibly serves to trigger the transformation process.

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40

Jarvis, J. C., H. Sutherland, C. N. Mayne, S. J. Gilroy, and S. Salmons. "Induction of a fast-oxidative phenotype by chronic muscle stimulation: mechanical and biochemical studies." American Journal of Physiology-Cell Physiology 270, no. 1 (1996): C306—C312. http://dx.doi.org/10.1152/ajpcell.1996.270.1.c306.

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We studied changes in the mechanical properties and myosin isoform composition of rabbit tibialis anterior muscles that were subjected to continuous stimulation at 2.5 Hz for up to 12 wk. The effects of stimulation at 2.5 Hz were less profound than those observed for the same duration of stimulation at 10 Hz (12). Stimulation at 10 Hz for 12 wk induced complete transformation to a slow-contracting muscle homogeneous in slow myosin isoforms; stimulation for the same period at 2.5 Hz resulted in moderate changes in contractile speed and a very small increase in the synthesis of slow myosin isoforms. On the other hand, the fatigue resistance of muscles stimulated at 2.5 Hz was as great, in both isometric and dynamic fatigue tests, as that of the muscles stimulated at 10 Hz. Thus entire fast skeletal muscles can be transformed to a state in which fast myosin isoforms continue to be synthesized, but the oxidative capacity is sufficient to support sustained working at a higher power output than that associated with slow muscle.

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41

Abouelmagd, Elbaz I., A. Mostafa, and Juan L. G. Guirao. "A First Order Automated Lie Transform." International Journal of Bifurcation and Chaos 25, no. 14 (2015): 1540026. http://dx.doi.org/10.1142/s021812741540026x.

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The objective of the present paper is to focus on the problem of the normalization of a Hamiltonian system via the elimination of angle variables involved using the Lie transform technique. The algorithm that we construct assumes that the Hamiltonian is periodic in [Formula: see text] angle variables, with two rates: fast and slow. If the angle variables have the same rate only one transformation is required. The equations needed to evaluate the elements of each transformation and the secular perturbations are constructed.

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Ma, Manting, Bolin Cai, Liang Jiang, et al. "lncRNA-Six1 Is a Target of miR-1611 that Functions as a ceRNA to Regulate Six1 Protein Expression and Fiber Type Switching in Chicken Myogenesis." Cells 7, no. 12 (2018): 243. http://dx.doi.org/10.3390/cells7120243.

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Emerging studies indicate important roles for non-coding RNAs (ncRNAs) as essential regulators in myogenesis, but relatively less is known about their function. In our previous study, we found that lncRNA-Six1 can regulate Six1 in cis to participate in myogenesis. Here, we studied a microRNA (miRNA) that is specifically expressed in chickens (miR-1611). Interestingly, miR-1611 was found to contain potential binding sites for both lncRNA-Six1 and Six1, and it can interact with lncRNA-Six1 to regulate Six1 expression. Overexpression of miR-1611 represses the proliferation and differentiation of myoblasts. Moreover, miR-1611 is highly expressed in slow-twitch fibers, and it drives the transformation of fast-twitch muscle fibers to slow-twitch muscle fibers. Together, these data demonstrate that miR-1611 can mediate the regulation of Six1 by lncRNA-Six1, thereby affecting proliferation and differentiation of myoblasts and transformation of muscle fiber types.

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Al-Iedani, Intessar, and Zoran Gajic. "Optimal Control of Wind Turbine Systems via Time-Scale Decomposition." Energies 13, no. 2 (2020): 287. http://dx.doi.org/10.3390/en13020287.

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In this paper, we design an optimal controller for a wind turbine (WT) with doubly-fed induction generator (DFIG) by decomposing the algebraic Riccati equation (ARE) of the singularly perturbed wind turbine system into two reduced-order AREs that correspond to the slow and fast time scales. In addition, we derive a mathematical expression to obtain the optimal regulator gains with respect to the optimal pure-slow and pure-fast, reduced-order Kalman filters and linear quadratic Gaussian (LQG) controllers. Using this method allows the design of the linear controllers for slow and fast subsystems independently, thus, achieving complete separation and parallelism in the design process. This solves the corresponding ill-conditioned problem and reduces the complexity that arises when the number of wind turbines integrated to the power system increases. The reduced-order systems are compared to the original full-order system to validate the performance of the proposed method when a wind turbulence and a large-signal disturbance are applied to the system. In addition, we show that the similarity transformation does not preserve the performance index value in case of Kalman filter and the corresponding LQG controller.

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Döbelin, Nicola, Laëtitia Galea, Urs Eggenberger, José M. F. Ferreira та Marc Bohner. "Recrystallization of Amorphized α-TCP". Key Engineering Materials 493-494 (жовтень 2011): 219–24. http://dx.doi.org/10.4028/www.scientific.net/kem.493-494.219.

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Phase-pure α-TCP powder was milled using a high-energy planetary mill to obtain a partially X-ray amorphous material. Calcination at temperatures between 350 and 600 °C was employed to recrystallize the powder. The phase composition as a function of calcination time and temperature was determinedin-situusing high-temperature XRD equipment. It was found that the amorphous fraction recrystallized mainly to α-TCP, with only small amounts of β-TCP formed. At low temperatures (≤ 450 °C), a stable composition with approximately 85 wt-% α-TCP was found once 100% crystallinity was reached. The time required to reach full crystallinity depended on the calcination temperature. For temperatures > 450 °C a slow transformation to β-TCP was observed. The transformation rate depended on the calcination temperature and on the milling intensity. A moderately milled powder recrystallized to α-TCP, followed by a slow transformation to β-TCP at 600 °C, whereas an intensely milled powder also recrystallized to α-TCP, followed by a fast transformation to β-TCP at the same temperature.

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45

Jardón-Kojakhmetov, Hildeberto, and Christian Kuehn. "On Fast–Slow Consensus Networks with a Dynamic Weight." Journal of Nonlinear Science 30, no. 6 (2020): 2737–86. http://dx.doi.org/10.1007/s00332-020-09634-9.

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Abstract We study dynamic networks under an undirected consensus communication protocol and with one state-dependent weighted edge. We assume that the aforementioned dynamic edge can take values over the whole real numbers, and that its behaviour depends on the nodes it connects and on an extrinsic slow variable. We show that, under mild conditions on the weight, there exists a reduction such that the dynamics of the network are organized by a transcritical singularity. As such, we detail a slow passage through a transcritical singularity for a simple network, and we observe that an exchange between consensus and clustering of the nodes is possible. In contrast to the classical planar fast–slow transcritical singularity, the network structure of the system under consideration induces the presence of a maximal canard. Our main tool of analysis is the blow-up method. Thus, we also focus on tracking the effects of the blow-up transformation on the network’s structure. We show that on each blow-up chart one recovers a particular dynamic network related to the original one. We further indicate a numerical issue produced by the slow passage through the transcritical singularity.

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Vissing, Kristian, Jesper L. Andersen, Stephen D. R. Harridge, et al. "Gene expression of myogenic factors and phenotype-specific markers in electrically stimulated muscle of paraplegics." Journal of Applied Physiology 99, no. 1 (2005): 164–72. http://dx.doi.org/10.1152/japplphysiol.01172.2004.

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The transcription factors myogenin and MyoD have been suggested to be involved in maintaining slow and fast muscle-fiber phenotypes, respectively, in rodents. Whether this is also the case in human muscle is unknown. To test this, 4 wk of chronic, low-frequency electrical stimulation training of the tibialis anterior muscle of paraplegic subjects were used to evoke a fast-to-slow transformation in muscle phenotype. It was hypothesized that this would result from an upregulation of myogenin and a downregulation of MyoD. The training evoked the expected mRNA increase for slow fiber-specific markers myosin heavy chain I and 3-hydroxyacyl-CoA dehydrogenase A, whereas an mRNA decrease was seen for fast fiber-specific markers myosin heavy chain IIx and glycerol phosphate dehydrogenase. Although the slow fiber-specific markers citrate synthase and muscle fatty acid binding protein did not display a significant increase in mRNA, they did tend to increase. As hypothesized, myogenin mRNA was upregulated. However, contrary to the hypothesis, MyoD mRNA also increased, although later than myogenin. The mRNA levels of the other myogenic regulatory factor family members, myogenic factor 5 and myogenic regulatory factor 4, and the myocyte enhancer factor (MEF) family members, MEF-2A and MEF-2C, did not change. The results indicate that myogenin is indeed involved in the regulation of the slow oxidative phenotype in human skeletal muscle fibers, whereas MyoD appears to have a more complex regulatory function.

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Deng, Lulu, Long Li, Cheng Zou, Chengchi Fang, and Changchun Li. "Characterization and Functional Analysis of Polyadenylation Sites in Fast and Slow Muscles." BioMed Research International 2020 (March 16, 2020): 1–13. http://dx.doi.org/10.1155/2020/2626584.

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Many increasing documents have proved that alternative polyadenylation (APA) events with different polyadenylation sites (PAS) contribute to posttranscriptional regulation. However, little is known about the detailed molecular features of PASs and its role in porcine fast and slow skeletal muscles through microRNAs (miRNAs) and RNA binding proteins (RBPs). In this study, we combined single-molecule real-time sequencing and Illumina RNA-seq datasets to comprehensively analyze polyadenylation in pigs. We identified a total of 10,334 PASs, of which 8734 were characterized by reference genome annotation. 32.86% of PAS-associated genes were determined to have more than one PAS. Further analysis demonstrated that tissue-specific PASs between fast and slow muscles were enriched in skeletal muscle development pathways. In addition, we obtained 1407 target genes regulated by APA events through potential binding 69 miRNAs and 28 RBPs in variable 3′ UTR regions and some are involved in myofiber transformation. Furthermore, the de novo motif search confirmed that the most common usage of canonical motif AAUAAA and three types of PASs may be related to the strength of motifs. In summary, our results provide a useful annotation of PASs for pig transcriptome and suggest that APA may serve as a role in fast and slow muscle development under the regulation of miRNAs and RBPs.

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Choudhary, M., and C. C. Laurie. "Use of in vitro mutagenesis to analyze the molecular basis of the difference in Adh expression associated with the allozyme polymorphism in Drosophila melanogaster." Genetics 129, no. 2 (1991): 481–88. http://dx.doi.org/10.1093/genetics/129.2.481.

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Abstract In natural populations of Drosophila melanogaster, the alcohol dehydrogenase (Adh) locus is polymorphic for two allozymes, designated Slow and Fast. Fast homozygotes generally have a two- to threefold higher ADH activity level than Slow homozygotes for two reasons: they have a higher concentration of ADH protein and the Fast protein has a higher catalytic efficiency. DNA sequencing studies have shown that the two allozymes generally differ by only a single amino acid at residue 192, which must therefore be the cause of the catalytic efficiency difference. A previous P element-transformation experiment mapped the difference in ADH protein level to a 2.3-kb HpaI/ClaI restriction fragment; which contains all of the Adh coding sequences but excludes all of the 5' flanking region of the distal transcriptional unit. Here we report the results of a site-directed in vitro mutagenesis experiment designed to investigate the effects of the amino acid replacement. This replacement has the expected effect on catalytic efficiency, but there is no detectable effect on the concentration of ADH protein estimated immunologically. This result shows that the average difference in ADH protein level between the allozymic classes is due to linkage disequilibrium between the amino acid replacement and one or more other polymorphisms within the HpaI/ClaI fragment. Sequence analysis of several Fast and Slow alleles suggested that the other polymorphism might be a silent substitution at nucleotide 1443, but another in vitro mutagenesis experiment reported here shows that this is not the case. Therefore, the molecular basis of the difference in ADH protein concentration between the allozymic classes remains an open question.

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Opathalage, Achini, Michael M. Norton, Michael P. N. Juniper, et al. "Self-organized dynamics and the transition to turbulence of confined active nematics." Proceedings of the National Academy of Sciences 116, no. 11 (2019): 4788–97. http://dx.doi.org/10.1073/pnas.1816733116.

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We study how confinement transforms the chaotic dynamics of bulk microtubule-based active nematics into regular spatiotemporal patterns. For weak confinements in disks, multiple continuously nucleating and annihilating topological defects self-organize into persistent circular flows of either handedness. Increasing confinement strength leads to the emergence of distinct dynamics, in which the slow periodic nucleation of topological defects at the boundary is superimposed onto a fast procession of a pair of defects. A defect pair migrates toward the confinement core over multiple rotation cycles, while the associated nematic director field evolves from a distinct double spiral toward a nearly circularly symmetric configuration. The collapse of the defect orbits is punctuated by another boundary-localized nucleation event, that sets up long-term doubly periodic dynamics. Comparing experimental data to a theoretical model of an active nematic reveals that theory captures the fast procession of a pair of +1/2 defects, but not the slow spiral transformation nor the periodic nucleation of defect pairs. Theory also fails to predict the emergence of circular flows in the weak confinement regime. The developed confinement methods are generalized to more complex geometries, providing a robust microfluidic platform for rationally engineering 2D autonomous flows.

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Sultan, Karim R., Bernd T. Dittrich, and Dirk Pette. "Calpain activity in fast, slow, transforming, and regenerating skeletal muscles of rat." American Journal of Physiology-Cell Physiology 279, no. 3 (2000): C639—C647. http://dx.doi.org/10.1152/ajpcell.2000.279.3.c639.

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Fiber-type transitions in adult skeletal muscle induced by chronic low-frequency stimulation (CLFS) encompass coordinated exchanges of myofibrillar protein isoforms. CLFS-induced elevations in cytosolic Ca2+ could activate proteases, especially calpains, the major Ca2+-regulated cytosolic proteases. Calpain activity determined by a fluorogenic substrate in the presence of unaltered endogenous calpastatin activities increased twofold in low-frequency-stimulated extensor digitorum longus (EDL) muscle, reaching a level intermediate between normal fast- and slow-twitch muscles. μ- and m-calpains were delineated by a calpain-specific zymographical assay that assessed total activities independent of calpastatin and distinguished between native and processed calpains. Contrary to normal EDL, structure-bound, namely myofibrillar and microsomal calpains, were abundant in soleus muscle. However, the fast-to-slow conversion of EDL was accompanied by an early translocation of cytosolic μ-calpain, suggesting that myofibrillar and microsomal μ-calpain was responsible for the twofold increase in activity and thus involved in controlled proteolysis during fiber transformation. This is in contrast to muscle regeneration where m-calpain translocation predominated. Taken together, we suggest that translocation is an important step in the control of calpain activity in skeletal muscle in vivo.

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Journal articles on the topic 'Fast-to-slow transformation'

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