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Sample records for activated satellite cells

  1. M-cadherin-mediated intercellular interactions activate satellite cell division.

    PubMed

    Marti, Merce; Montserrat, Núria; Pardo, Cristina; Mulero, Lola; Miquel-Serra, Laia; Rodrigues, Alexandre Miguel Cavaco; Andrés Vaquero, José; Kuebler, Bernd; Morera, Cristina; Barrero, María José; Izpisua Belmonte, Juan Carlos

    2013-11-15

    Adult muscle stem cells and their committed myogenic precursors, commonly referred to as the satellite cell population, are involved in both muscle growth after birth and regeneration after damage. It has been previously proposed that, under these circumstances, satellite cells first become activated, divide and differentiate, and only later fuse to the existing myofiber through M-cadherin-mediated intercellular interactions. Our data show that satellite cells fuse with the myofiber concomitantly to cell division, and only when the nuclei of the daughter cells are inside the myofiber, do they complete the process of differentiation. Here we demonstrate that M-cadherin plays an important role in cell-to-cell recognition and fusion, and is crucial for cell division activation. Treatment of satellite cells with M-cadherin in vitro stimulates cell division, whereas addition of anti-M-cadherin antibodies reduces the cell division rate. Our results suggest an alternative model for the contribution of satellite cells to muscle development, which might be useful in understanding muscle regeneration, as well as muscle-related dystrophies.

  2. Satellite cell activity in muscle regeneration after contusion in rats.

    PubMed

    Srikuea, Ratchakrit; Pholpramool, Chumpol; Kitiyanant, Yindee; Yimlamai, Tossaporn

    2010-11-01

    1. The role of satellite cells in muscle growth during development is well documented, but the involvement of these cells in muscle repair after contusion is less well known. In the present study, we investigated the time-course of satellite cell activity (from 3h to 7days) after contusion of rat gastrocnemius muscle using specific molecular markers for immunofluorescence and real-time polymerase chain reaction (PCR). 2. Inflammation of the injured muscle occurred within 6h, followed by disintegration of the damaged myofibres within 12h. Newly formed myofibres appeared by Day 7. 3. The number of MyoD-positive nuclei (activated satellite cells) in the injured muscle was significantly increased by 6h, reaching a maximum by 12h after contusion. However, the number of MyoD-positive nuclei decreased towards control levels by Day 7. Changes in the number of bromodeoxyuridine-labelled nuclei (proliferating satellite cells) paralleled the changes seen in the number of MyoD-positive nuclei. Conversely, expression of myogenin protein was not apparent until Day 3 and increased further by Day 7. Colabelling of MyoD and myogenin was seen in only a few cells. 4. The time-course of MyoD mRNA expression corresponded with MyoD protein expression. However, there were two peaks in myogenin mRNA expression: 6h and Day 7 after contusion. The second peak coincided with upregulation of myostatin mRNA levels. 5. The results of the present study suggest that contusion activates a homogeneous population of satellite cells to proliferate within 3days, followed by differentiation to form new myofibres. The latter may be regulated, in part, by myostatin.

  3. Stra13 regulates satellite cell activation by antagonizing Notch signaling

    PubMed Central

    Sun, Hong; Li, Li; Vercherat, Cécile; Gulbagci, Neriman Tuba; Acharjee, Sujata; Li, Jiali; Chung, Teng-Kai; Thin, Tin Htwe; Taneja, Reshma

    2007-01-01

    Satellite cells play a critical role in skeletal muscle regeneration in response to injury. Notch signaling is vital for satellite cell activation and myogenic precursor cell expansion but inhibits myogenic differentiation. Thus, precise spatial and temporal regulation of Notch activity is necessary for efficient muscle regeneration. We report that the basic helix-loop-helix transcription factor Stra13 modulates Notch signaling in regenerating muscle. Upon injury, Stra13−/− mice exhibit increased cellular proliferation, elevated Notch signaling, a striking regeneration defect characterized by degenerated myotubes, increased mononuclear cells, and fibrosis. Stra13−/− primary myoblasts also exhibit enhanced Notch activity, increased proliferation, and defective differentiation. Inhibition of Notch signaling ex vivo and in vivo ameliorates the phenotype of Stra13−/− mutants. We demonstrate in vitro that Stra13 antagonizes Notch activity and reverses the Notch-imposed inhibition of myogenesis. Thus, Stra13 plays an important role in postnatal myogenesis by attenuating Notch signaling to reduce myoblast proliferation and promote myogenic differentiation. PMID:17502421

  4. Halofuginone promotes satellite cell activation and survival in muscular dystrophies.

    PubMed

    Barzilai-Tutsch, Hila; Bodanovsky, Anna; Maimon, Hadar; Pines, Mark; Halevy, Orna

    2016-01-01

    Halofuginone is a leading agent in preventing fibrosis and inflammation in various muscular dystrophies. We hypothesized that in addition to these actions, halofuginone directly promotes the cell-cycle events of satellite cells in the mdx and dysf(-/-) mouse models of early-onset Duchenne muscular dystrophy and late-onset dysferlinopathy, respectively. In both models, addition of halofuginone to freshly prepared single gastrocnemius myofibers derived from 6-week-old mice increased BrdU incorporation at as early as 18h of incubation, as well as phospho-histone H3 (PHH3) and MyoD protein expression in the attached satellite cells, while having no apparent effect on myofibers derived from wild-type mice. BrdU incorporation was abolished by an inhibitor of mitogen-activated protein kinase/extracellular signal-regulated protein kinase, suggesting involvement of this pathway in mediating halofuginone's effects on cell-cycle events. In cultures of myofibers and myoblasts isolated from dysf(-/-) mice, halofuginone reduced Bax and induced Bcl2 expression levels and induced Akt phosphorylation in a time-dependent manner. Addition of an inhibitor of the phosphinositide-3-kinase/Akt pathway reversed the halofuginone-induced cell survival, suggesting this pathway's involvement in mediating halofuginone's effects on survival. Thus, in addition to its known role in inhibiting fibrosis and inflammation, halofuginone plays a direct role in satellite cell activity and survival in muscular dystrophies, regardless of the mutation. These actions are of the utmost importance for improving muscle pathology and function in muscular dystrophies.

  5. Skeletal Muscle Satellite Cell Activation Following Cutaneous Burn in Rats

    DTIC Science & Technology

    2013-12-01

    mechanisms of long-term muscle atrophy. # 2012 Elsevier Ltd and ISBI. All rights reserved. * Corresponding author at: US Army Institute of Surgical...understanding of the impact of burn on satellite cell functionality will allow us to identify the cellular mechanisms of long-term muscle atrophy after...fibers. J Biophys Biochem Cytol 1961;9:493–5. [12] Hawke TJ, Garry DJ. Myogenic satellite cells: physiology to molecular biology. J Appl Physiol 2001;91

  6. Satellite cell activity, without expansion, after nonhypertrophic stimuli

    PubMed Central

    Joanisse, Sophie; McKay, Bryon R.; Nederveen, Joshua P.; Scribbans, Trisha D.; Gurd, Brendon J.; Gillen, Jenna B.; Gibala, Martin J.; Tarnopolsky, Mark

    2015-01-01

    The purpose of the present studies was to determine the effect of various nonhypertrophic exercise stimuli on satellite cell (SC) pool activity in human skeletal muscle. Previously untrained men and women (men: 29 ± 9 yr and women: 29 ± 2 yr, n = 7 each) completed 6 wk of very low-volume high-intensity sprint interval training. In a separate study, recreationally active men (n = 16) and women (n = 3) completed 6 wk of either traditional moderate-intensity continuous exercise (n = 9, 21 ± 4 yr) or low-volume sprint interval training (n = 10, 21 ± 2 yr). Muscle biopsies were obtained from the vastus lateralis before and after training. The fiber type-specific SC response to training was determined, as was the activity of the SC pool using immunofluorescent microscopy of muscle cross sections. Training did not induce hypertrophy, as assessed by muscle cross-sectional area, nor did the SC pool expand in any group. However, there was an increase in the number of active SCs after each intervention. Specifically, the number of activated (Pax7+/MyoD+, P ≤ 0.05) and differentiating (Pax7−/MyoD+, P ≤ 0.05) SCs increased after each training intervention. Here, we report evidence of activated and cycling SCs that may or may not contribute to exercise-induced adaptations while the SC pool remains constant after three nonhypertrophic exercise training protocols. PMID:26333785

  7. Supplemental nitric oxide augments satellite cell activity on cultured myofibers from aged mice.

    PubMed

    Betters, Jenna L; Lira, Vitor A; Soltow, Quinlyn A; Drenning, Jason A; Criswell, David S

    2008-12-01

    Skeletal muscle regenerative potential is reduced with aging. We hypothesized that in vitro activation of muscle satellite cells would be compromised, and that nitric oxide (NO) supplementation would improve satellite cell activity in old muscle. Single intact myofibers were isolated from the gastrocnemius muscles of young (2 mo), adult (10 mo), and aged (22 mo) mice. Fibers were centrifuged to stimulate satellite cells and incubated with L-arginine (2mM), the NO donor, diethylenetriamine NONOate (DETA-NO; 10 microM), or control media for 48 h. The number of activated satellite cells after centrifugation was reduced in aged fibers compared to young and adult. L-arginine or DETA-NO treatment increased satellite cell activation in all age groups. However, an age-dependent deficit in satellite cell activity persisted within treatment groups. In separate fibers, exogenous HGF was equally effective in activating satellite cells across age groups, indicating that events downstream of HGF release are intact in aged muscle. These data suggest that l-arginine bioavailability and NO production limit muscle satellite cell activity in response to a submaximal mechanical stimulus, regardless of age. Further, the decline in satellite cell activity in early senescence can be partially abrogated by exogenous L-arginine or an NO donor.

  8. AMP-activated protein kinase stimulates Warburg-like glycolysis and activation of satellite cells during muscle regeneration.

    PubMed

    Fu, Xing; Zhu, Mei-Jun; Dodson, Mike V; Du, Min

    2015-10-30

    Satellite cells are the major myogenic stem cells residing inside skeletal muscle and are indispensable for muscle regeneration. Satellite cells remain largely quiescent but are rapidly activated in response to muscle injury, and the derived myogenic cells then fuse to repair damaged muscle fibers or form new muscle fibers. However, mechanisms eliciting metabolic activation, an inseparable step for satellite cell activation following muscle injury, have not been defined. We found that a noncanonical Sonic Hedgehog (Shh) pathway is rapidly activated in response to muscle injury, which activates AMPK and induces a Warburg-like glycolysis in satellite cells. AMPKα1 is the dominant AMPKα isoform expressed in satellite cells, and AMPKα1 deficiency in satellite cells impairs their activation and myogenic differentiation during muscle regeneration. Drugs activating noncanonical Shh promote proliferation of satellite cells, which is abolished because of satellite cell-specific AMPKα1 knock-out. Taken together, AMPKα1 is a critical mediator linking noncanonical Shh pathway to Warburg-like glycolysis in satellite cells, which is required for satellite activation and muscle regeneration.

  9. Fractalkine mediates inflammatory pain through activation of satellite glial cells.

    PubMed

    Souza, Guilherme R; Talbot, Jhimmy; Lotufo, Celina M; Cunha, Fernando Q; Cunha, Thiago M; Ferreira, Sérgio H

    2013-07-02

    The activation of the satellite glial cells (SGCs) surrounding the dorsal root ganglion (DRG) neurons appears to play a role in pathological pain. We tested the hypothesis that fractalkine, which is constitutively expressed by primary nociceptive neurons, is the link between peripheral inflammation and the activation of SGCs and is thus responsible for the genesis of the inflammatory pain. The injection of carrageenin into the rat hind paw induced a decrease in the mechanical nociceptive threshold (hypernociception), which was associated with an increase in mRNA and GFAP protein expression in the DRG. Both events were inhibited by anti-fractalkine antibody administered directly into the DRG (L5) [intraganglionar (i.gl.)]. The administration of fractalkine into the DRG (L5) produced mechanical hypernociception in a dose-, time-, and CX3C receptor-1 (CX3CR1)-dependent manner. Fractalkine's hypernociceptive effect appears to be indirect, as it was reduced by local treatment with anti-TNF-α antibody, IL-1-receptor antagonist, or indomethacin. Accordingly, the in vitro incubation of isolated and cultured SGC with fractalkine induced the production/release of TNF-α, IL-1β, and prostaglandin E2. Finally, treatment with i.gl. fluorocitrate blocked fractalkine (i.gl.)- and carrageenin (paw)-induced hypernociception. Overall, these results suggest that, during peripheral inflammation, fractalkine is released in the DRG and contributes to the genesis of inflammatory hypernociception. Fractalkine's effect appears to be dependent on the activation of the SGCs, leading to the production of TNFα, IL-1β, and prostanoids, which are likely responsible for the maintenance of inflammatory pain. Thus, these results indicate that the inhibition of fractalkine/CX3CR1 signaling in SGCs may serve as a target to control inflammatory pain.

  10. Discovery of Novel Small Molecules that Activate Satellite Cell Proliferation and Enhance Repair of Damaged Muscle.

    PubMed

    Billin, Andrew N; Bantscheff, Marcus; Drewes, Gerard; Ghidelli-Disse, Sonja; Holt, Jason A; Kramer, Henning F; McDougal, Alan J; Smalley, Terry L; Wells, Carrow I; Zuercher, William J; Henke, Brad R

    2016-02-19

    Skeletal muscle progenitor stem cells (referred to as satellite cells) represent the primary pool of stem cells in adult skeletal muscle responsible for the generation of new skeletal muscle in response to injury. Satellite cells derived from aged muscle display a significant reduction in regenerative capacity to form functional muscle. This decrease in functional recovery has been attributed to a decrease in proliferative capacity of satellite cells. Hence, agents that enhance the proliferative abilities of satellite cells may hold promise as therapies for a variety of pathological settings, including repair of injured muscle and age- or disease-associated muscle wasting. Through phenotypic screening of isolated murine satellite cells, we identified a series of 2,4-diaminopyrimidines (e.g., 2) that increased satellite cell proliferation. Importantly, compound 2 was effective in accelerating repair of damaged skeletal muscle in an in vivo mouse model of skeletal muscle injury. While these compounds were originally prepared as c-Jun N-terminal kinase 1 (JNK-1) inhibitors, structure-activity analyses indicated JNK-1 inhibition does not correlate with satellite cell activity. Screening against a broad panel of kinases did not result in identification of an obvious molecular target, so we conducted cell-based proteomics experiments in an attempt to identify the molecular target(s) responsible for the potentiation of the satellite cell proliferation. These data provide the foundation for future efforts to design improved small molecules as potential therapeutics for muscle repair and regeneration.

  11. Salamander limb regeneration involves the activation of a multipotent skeletal muscle satellite cell population.

    PubMed

    Morrison, Jamie I; Lööf, Sara; He, Pingping; Simon, András

    2006-01-30

    In contrast to mammals, salamanders can regenerate complex structures after injury, including entire limbs. A central question is whether the generation of progenitor cells during limb regeneration and mammalian tissue repair occur via separate or overlapping mechanisms. Limb regeneration depends on the formation of a blastema, from which the new appendage develops. Dedifferentiation of stump tissues, such as skeletal muscle, precedes blastema formation, but it was not known whether dedifferentiation involves stem cell activation. We describe a multipotent Pax7+ satellite cell population located within the skeletal muscle of the salamander limb. We demonstrate that skeletal muscle dedifferentiation involves satellite cell activation and that these cells can contribute to new limb tissues. Activation of salamander satellite cells occurs in an analogous manner to how the mammalian myofiber mobilizes stem cells during skeletal muscle tissue repair. Thus, limb regeneration and mammalian tissue repair share common cellular and molecular programs. Our findings also identify satellite cells as potential targets in promoting mammalian blastema formation.

  12. Skeletal muscle satellite cells

    NASA Technical Reports Server (NTRS)

    Schultz, E.; McCormick, K. M.

    1994-01-01

    Evidence now suggests that satellite cells constitute a class of myogenic cells that differ distinctly from other embryonic myoblasts. Satellite cells arise from somites and first appear as a distinct myoblast type well before birth. Satellite cells from different muscles cannot be functionally distinguished from one another and are able to provide nuclei to all fibers without regard to phenotype. Thus, it is difficult to ascribe any significant function to establishing or stabilizing fiber type, even during regeneration. Within a muscle, satellite cells exhibit marked heterogeneity with respect to their proliferative behavior. The satellite cell population on a fiber can be partitioned into those that function as stem cells and those which are readily available for fusion. Recent studies have shown that the cells are not simply spindle shaped, but are very diverse in their morphology and have multiple branches emanating from the poles of the cells. This finding is consistent with other studies indicating that the cells have the capacity for extensive migration within, and perhaps between, muscles. Complexity of cell shape usually reflects increased cytoplasmic volume and organelles including a well developed Golgi, and is usually associated with growing postnatal muscle or muscles undergoing some form of induced adaptive change or repair. The appearance of activated satellite cells suggests some function of the cells in the adaptive process through elaboration and secretion of a product. Significant advances have been made in determining the potential secretion products that satellite cells make. The manner in which satellite cell proliferative and fusion behavior is controlled has also been studied. There seems to be little doubt that cellcell coupling is not how satellite cells and myofibers communicate. Rather satellite cell regulation is through a number of potential growth factors that arise from a number of sources. Critical to the understanding of this form

  13. Sphingosine-1-phosphate mediates epidermal growth factor-induced muscle satellite cell activation.

    PubMed

    Nagata, Yosuke; Ohashi, Kazuya; Wada, Eiji; Yuasa, Yuki; Shiozuka, Masataka; Nonomura, Yoshiaki; Matsuda, Ryoichi

    2014-08-01

    Skeletal muscle can regenerate repeatedly due to the presence of resident stem cells, called satellite cells. Because satellite cells are usually quiescent, they must be activated before participating in muscle regeneration in response to stimuli such as injury, overloading, and stretch. Although satellite cell activation is a crucial step in muscle regeneration, little is known of the molecular mechanisms controlling this process. Recent work showed that the bioactive lipid sphingosine-1-phosphate (S1P) plays crucial roles in the activation, proliferation, and differentiation of muscle satellite cells. We investigated the role of growth factors in S1P-mediated satellite cell activation. We found that epidermal growth factor (EGF) in combination with insulin induced proliferation of quiescent undifferentiated mouse myoblast C2C12 cells, which are also known as reserve cells, in serum-free conditions. Sphingosine kinase activity increased when reserve cells were stimulated with EGF. Treatment of reserve cells with the D-erythro-N,N-dimethylsphingosine, Sphingosine Kinase Inhibitor, or siRNA duplexes specific for sphingosine kinase 1, suppressed EGF-induced C2C12 activation. We also present the evidence showing the S1P receptor S1P2 is involved in EGF-induced reserve cell activation. Moreover, we demonstrated a combination of insulin and EGF promoted activation of satellite cells on single myofibers in a manner dependent on SPHK and S1P2. Taken together, our observations show that EGF-induced satellite cell activation is mediated by S1P and its receptor.

  14. Neonatal phosphate nutrition alters in vivo and in vitro satellite cell activity in pigs.

    PubMed

    Alexander, Lindsey S; Seabolt, Brynn S; Rhoads, Robert P; Stahl, Chad H

    2012-06-01

    Satellite cell activity is necessary for postnatal skeletal muscle growth. Severe phosphate (PO(4)) deficiency can alter satellite cell activity, however the role of neonatal PO(4) nutrition on satellite cell biology remains obscure. Twenty-one piglets (1 day of age, 1.8 ± 0.2 kg BW) were pair-fed liquid diets that were either PO(4) adequate (0.9% total P), supra-adequate (1.2% total P) in PO(4) requirement or deficient (0.7% total P) in PO(4) content for 12 days. Body weight was recorded daily and blood samples collected every 6 days. At day 12, pigs were orally dosed with BrdU and 12 h later, satellite cells were isolated. Satellite cells were also cultured in vitro for 7 days to determine if PO(4) nutrition alters their ability to proceed through their myogenic lineage. Dietary PO(4) deficiency resulted in reduced (P < 0.05) sera PO(4) and parathyroid hormone (PTH) concentrations, while supra-adequate dietary PO(4) improved (P < 0.05) feed conversion efficiency as compared to the PO(4) adequate group. In vivo satellite cell proliferation was reduced (P < 0.05) among the PO(4) deficient pigs, and these cells had altered in vitro expression of markers of myogenic progression. Further work to better understand early nutritional programming of satellite cells and the potential benefits of emphasizing early PO(4) nutrition for future lean growth potential is warranted.

  15. Sphingosine-1-phosphate mediates epidermal growth factor-induced muscle satellite cell activation

    SciTech Connect

    Nagata, Yosuke Ohashi, Kazuya; Wada, Eiji; Yuasa, Yuki; Shiozuka, Masataka; Nonomura, Yoshiaki; Matsuda, Ryoichi

    2014-08-01

    Skeletal muscle can regenerate repeatedly due to the presence of resident stem cells, called satellite cells. Because satellite cells are usually quiescent, they must be activated before participating in muscle regeneration in response to stimuli such as injury, overloading, and stretch. Although satellite cell activation is a crucial step in muscle regeneration, little is known of the molecular mechanisms controlling this process. Recent work showed that the bioactive lipid sphingosine-1-phosphate (S1P) plays crucial roles in the activation, proliferation, and differentiation of muscle satellite cells. We investigated the role of growth factors in S1P-mediated satellite cell activation. We found that epidermal growth factor (EGF) in combination with insulin induced proliferation of quiescent undifferentiated mouse myoblast C2C12 cells, which are also known as reserve cells, in serum-free conditions. Sphingosine kinase activity increased when reserve cells were stimulated with EGF. Treatment of reserve cells with the D-erythro-N,N-dimethylsphingosine, Sphingosine Kinase Inhibitor, or siRNA duplexes specific for sphingosine kinase 1, suppressed EGF-induced C2C12 activation. We also present the evidence showing the S1P receptor S1P2 is involved in EGF-induced reserve cell activation. Moreover, we demonstrated a combination of insulin and EGF promoted activation of satellite cells on single myofibers in a manner dependent on SPHK and S1P2. Taken together, our observations show that EGF-induced satellite cell activation is mediated by S1P and its receptor. - Highlights: • EGF in combination with insulin induces proliferation of quiescent C2C12 cells. • Sphingosine kinase activity increases when reserve cells are stimulated with EGF. • EGF-induced activation of reserve cells is dependent on sphingosine kinase and ERK. • The S1P receptor S1P2 is involved in EGF-induced reserve cell activation. • EGF-induced reserve cell activation is mediated by S1P and its

  16. Regulation of the muscle fiber microenvironment by activated satellite cells during hypertrophy.

    PubMed

    Fry, Christopher S; Lee, Jonah D; Jackson, Janna R; Kirby, Tyler J; Stasko, Shawn A; Liu, Honglu; Dupont-Versteegden, Esther E; McCarthy, John J; Peterson, Charlotte A

    2014-04-01

    Our aim in the current study was to determine the necessity of satellite cells for long-term muscle growth and maintenance. We utilized a transgenic Pax7-DTA mouse model, allowing for the conditional depletion of > 90% of satellite cells with tamoxifen treatment. Synergist ablation surgery, where removal of synergist muscles places functional overload on the plantaris, was used to stimulate robust hypertrophy. Following 8 wk of overload, satellite cell-depleted muscle demonstrated an accumulation of extracellular matrix (ECM) and fibroblast expansion that resulted in reduced specific force of the plantaris. Although the early growth response was normal, an attenuation of hypertrophy measured by both muscle wet weight and fiber cross-sectional area occurred in satellite cell-depleted muscle. Isolated primary myogenic progenitor cells (MPCs) negatively regulated fibroblast ECM mRNA expression in vitro, suggesting a novel role for activated satellite cells/MPCs in muscle adaptation. These results provide evidence that satellite cells regulate the muscle environment during growth.

  17. Estrogen influences satellite cell activation and proliferation following downhill running in rats.

    PubMed

    Enns, Deborah L; Tiidus, Peter M

    2008-02-01

    To investigate the influence of estrogen on postexercise muscle repair processes, we examined the effects of estrogen supplementation (0.25-mg pellet) on numbers of myofibers positive for markers of total, activated, and proliferating satellite cells in rat skeletal muscles 72 h following downhill running. Ovariectomized female rats (n = 44) were divided into four groups (n = 11 per group): sham (no estrogen) controls (SC); sham, exercised (SE); estrogen-supplemented controls (EC); and estrogen-supplemented, exercised (EE). After 8 days of estrogen exposure, animals were exposed to 90 min of treadmill running at 17 m/min (-13.5 degrees ). Seventy-two hours later, soleus and white vastus muscles were removed and immunostained for total [paired box homeotic gene 7 (Pax7)], [activated myogenic differentiation factor D (MyoD)], and proliferating [5-bromo-2'-deoxyuridine (BrdU)] satellite cells. beta-Glucuronidase activity was increased (P < 0.05) in both muscles following exercise; however, the postexercise elevations in enzyme activity were attenuated in the EE group compared with the SE group in the soleus (P < 0.05). Immunohistochemical analysis revealed that exercised groups displayed increased numbers of myofibers containing total, activated, and proliferating satellite cells compared with control groups (P < 0.05). Furthermore, greater numbers of fibers positive for markers of total, activated, and proliferating satellite cells were observed postexercise in EE animals compared with SE animals for both muscles (P < 0.05). The results demonstrate that estrogen may potentially influence post-damage repair of skeletal muscle through activation of satellite cells.

  18. Muscle Atrophy Reversed by Growth Factor Activation of Satellite Cells in a Mouse Muscle Atrophy Model

    PubMed Central

    Hauerslev, Simon; Vissing, John; Krag, Thomas O.

    2014-01-01

    Muscular dystrophies comprise a large group of inherited disorders that lead to progressive muscle wasting. We wanted to investigate if targeting satellite cells can enhance muscle regeneration and thus increase muscle mass. We treated mice with hepatocyte growth factor and leukemia inhibitory factor under three conditions: normoxia, hypoxia and during myostatin deficiency. We found that hepatocyte growth factor treatment led to activation of the Akt/mTOR/p70S6K protein synthesis pathway, up-regulation of the myognic transcription factors MyoD and myogenin, and subsequently the negative growth control factor, myostatin and atrophy markers MAFbx and MuRF1. Hypoxia-induced atrophy was partially restored by hepatocyte growth factor combined with leukemia inhibitory factor treatment. Dividing satellite cells were three-fold increased in the treatment group compared to control. Finally, we demonstrated that myostatin regulates satellite cell activation and myogenesis in vivo following treatment, consistent with previous findings in vitro. Our results suggest, not only a novel in vivo pharmacological treatment directed specifically at activating the satellite cells, but also a myostatin dependent mechanism that may contribute to the progressive muscle wasting seen in severely affected patients with muscular dystrophy and significant on-going regeneration. This treatment could potentially be applied to many conditions that feature muscle wasting to increase muscle bulk and strength. PMID:24963862

  19. Muscle atrophy reversed by growth factor activation of satellite cells in a mouse muscle atrophy model.

    PubMed

    Hauerslev, Simon; Vissing, John; Krag, Thomas O

    2014-01-01

    Muscular dystrophies comprise a large group of inherited disorders that lead to progressive muscle wasting. We wanted to investigate if targeting satellite cells can enhance muscle regeneration and thus increase muscle mass. We treated mice with hepatocyte growth factor and leukemia inhibitory factor under three conditions: normoxia, hypoxia and during myostatin deficiency. We found that hepatocyte growth factor treatment led to activation of the Akt/mTOR/p70S6K protein synthesis pathway, up-regulation of the myognic transcription factors MyoD and myogenin, and subsequently the negative growth control factor, myostatin and atrophy markers MAFbx and MuRF1. Hypoxia-induced atrophy was partially restored by hepatocyte growth factor combined with leukemia inhibitory factor treatment. Dividing satellite cells were three-fold increased in the treatment group compared to control. Finally, we demonstrated that myostatin regulates satellite cell activation and myogenesis in vivo following treatment, consistent with previous findings in vitro. Our results suggest, not only a novel in vivo pharmacological treatment directed specifically at activating the satellite cells, but also a myostatin dependent mechanism that may contribute to the progressive muscle wasting seen in severely affected patients with muscular dystrophy and significant on-going regeneration. This treatment could potentially be applied to many conditions that feature muscle wasting to increase muscle bulk and strength.

  20. Regulation of myogenesis and skeletal muscle regeneration: effects of oxygen levels on satellite cell activity.

    PubMed

    Chaillou, Thomas; Lanner, Johanna T

    2016-12-01

    Reduced oxygen (O2) levels (hypoxia) are present during embryogenesis and exposure to altitude and in pathologic conditions. During embryogenesis, myogenic progenitor cells reside in a hypoxic microenvironment, which may regulate their activity. Satellite cells are myogenic progenitor cells localized in a local environment, suggesting that the O2 level could affect their activity during muscle regeneration. In this review, we present the idea that O2 levels regulate myogenesis and muscle regeneration, we elucidate the molecular mechanisms underlying myogenesis and muscle regeneration in hypoxia and depict therapeutic strategies using changes in O2 levels to promote muscle regeneration. Severe hypoxia (≤1% O2) appears detrimental for myogenic differentiation in vitro, whereas a 3-6% O2 level could promote myogenesis. Hypoxia impairs the regenerative capacity of injured muscles. Although it remains to be explored, hypoxia may contribute to the muscle damage observed in patients with pathologies associated with hypoxia (chronic obstructive pulmonary disease, and peripheral arterial disease). Hypoxia affects satellite cell activity and myogenesis through mechanisms dependent and independent of hypoxia-inducible factor-1α. Finally, hyperbaric oxygen therapy and transplantation of hypoxia-conditioned myoblasts are beneficial procedures to enhance muscle regeneration in animals. These therapies may be clinically relevant to treatment of patients with severe muscle damage.-Chaillou, T. Lanner, J. T. Regulation of myogenesis and skeletal muscle regeneration: effects of oxygen levels on satellite cell activity.

  1. A Role for Nitric Oxide in Muscle Repair: Nitric Oxide–mediated Activation of Muscle Satellite Cells

    PubMed Central

    Anderson, Judy E.

    2000-01-01

    Muscle satellite cells are quiescent precursors interposed between myofibers and a sheath of external lamina. Although their activation and recruitment to cycle enable muscle repair and adaptation, the activation signal is not known. Evidence is presented that nitric oxide (NO) mediates satellite cell activation, including morphological hypertrophy and decreased adhesion in the fiber-lamina complex. Activation in vivo occurred within 1 min after injury. Cell isolation and histology showed that pharmacological inhibition of nitric oxide synthase (NOS) activity prevented the immediate injury-induced myogenic cell release and delayed the hypertrophy of satellite cells in that muscle. Transient activation of satellite cells in contralateral muscles 10 min later suggested that a circulating factor may interact with NO-mediated signaling. Interestingly, satellite cell activation in muscles of mdx dystrophic mice and NOS-I knockout mice quantitatively resembled NOS-inhibited release of normal cells, in agreement with reports of displaced and reduced NOS expression in dystrophin-deficient mdx muscle and the complete loss of NOS-I expression in knockout mice. Brief NOS inhibition in normal and mdx mice during injury produced subtle alterations in subsequent repair, including apoptosis in myotube nuclei and myotube formation inside laminar sheaths. Longer NOS inhibition delayed and restricted the extent of repair and resulted in fiber branching. A model proposes the hypothesis that NO release mediates satellite cell activation, possibly via shear-induced rapid increases in NOS activity that produce “NO transients.” PMID:10793157

  2. Coordination of Satellite Cell Activation and Self-Renewal by Par-Complex-Dependent Asymmetric Activation of p38α/β MAPK

    PubMed Central

    Troy, Andrew; Cadwallader, Adam B.; Fedorov, Yuri; Tyner, Kristina; Tanaka, Kathleen Kelly; Olwin, Bradley B.

    2014-01-01

    SUMMARY In response to muscle injury, satellite cells activate the p38α/β MAPK pathway to exit quiescence, then proliferate, repair skeletal muscle, and self-renew, replenishing the quiescent satellite cell pool. Although satellite cells are capable of asymmetric division, the mechanisms regulating satellite cell self-renewal are not understood. We found that satellite cells, once activated, enter the cell cycle and a subset undergoes asymmetric division, renewing the satellite cell pool. Asymmetric localization of the Par complex activates p38α/β MAPK in only one daughter cell, inducing MyoD, which permits cell cycle entry and generates a proliferating myoblast. The absence of p38α/β MAPK signaling in the other daughter cell prevents MyoD induction, renewing the quiescent satellite cell. Thus, satellite cells employ a mechanism to generate distinct daughter cells, coupling the Par complex and p38α/β MAPK signaling to link the response to muscle injury with satellite cell self-renewal. PMID:23040480

  3. Activated satellite cells are present in uninjured extraocular muscles of mature mice.

    PubMed Central

    McLoon, Linda K; Wirtschafter, Jonathan

    2002-01-01

    PURPOSE: We recently demonstrated that there is a continuous process of myonuclear addition into normal, uninjured adult myofibers in rabbit extraocular muscles (EOM). This phenomenon is not seen in skeletal muscles from normal, adult limbs. These features may explain the selective involvement of the EOM in progressive external ophthalmoplegia and oculopharyngeal muscular dystrophy due to an accumulation of damaged DNA in mitochondria and nuclei within the EOM as a result of repeated cycling of the muscle satellite cells. Many testable hypotheses flow from these observations. We investigated whether continuous myonuclear addition is present in normal mouse EOM so that mouse models of genetic disorders can be used to study the pathogenic mechanisms and to test potential therapies for human muscle disorders. METHODS: Bromodeoxyuridine (brdU) was injected intraperitoneally into C57 adult mice every 2 hours for 12 hours. Twenty-four hours later the animals were sacrificed, and the globes with the muscles attached were prepared for immunohistochemical localization of brdU-positive nuclei within the EOM. All cross sections were immunostained for both brdU and either dystrophin or laminin. RESULTS: All the rectus muscles from the mouse EOM examined contained both satellite cells and myonuclei that were positive for brdU. This demonstrates the division of satellite cells and the fusion of their daughter cells with existing adult EOM myofibers in mice. CONCLUSIONS: These data indicate that the process of continuous myonuclear addition is also active in mouse EOM. These findings will allow various mutant mouse models to be used to study the pathogenesis and treatment of various muscle disorders. The existence of continuous myonuclear addition in adult, uninjured EOM fundamentally changes the accepted notion that EOM myofibers are postmitotic. PMID:12545684

  4. Satellite cell activation induced by aerobic muscle adaptation in response to endurance exercise in humans and rodents.

    PubMed

    Abreu, Phablo; Mendes, Sávio Victor Diógenes; Ceccatto, Vânia Marilande; Hirabara, Sandro Massao

    2017-02-01

    Although the requirement of satellite cells activation and expansion following injury, mechanical load or growth stimulus provoked by resistance exercise has been well established, their function in response to aerobic exercise adaptation remains unclear. A clear relationship between satellite cell expansion in fiber-type specific myosin heavy chain and aerobic performance has been related, independent of myonuclear accretion or muscle growth. However, the trigger for this activation process is not fully understood yet and it seems to be a multi-faceted and well-orchestrated process. Emerging in vitro studies suggest a role for metabolic pathways and oxygen availability for satellite cell activation, modulating the self-renewal potential and cell fate control. The goal of this review is to describe and discuss the current knowledge about the satellite cell activation and expansion in response to aerobic exercise adaptation in human and rodent models. Additionally, findings about the in vitro metabolic control, which seems be involved in the satellite cell activation and cell fate control, are presented and discussed.

  5. Satellite glial cells in dorsal root ganglia are activated in experimental autoimmune encephalomyelitis.

    PubMed

    Warwick, Rebekah A; Ledgerwood, Craig J; Brenner, Talma; Hanani, Menachem

    2014-05-21

    Pain is a serious and common problem with patients suffering from multiple sclerosis (MS). Very little has been done to investigate the peripheral mechanisms of pain in MS. Here we used a mouse model of experimental autoimmune encephalomyelitis (EAE) to investigate the possible contribution of satellite glial cells (SGCs) to pain in MS. EAE mice had reduced pain thresholds 10 days after disease induction. We examined dorsal root ganglia and found increased expression of glial fibrillary acidic protein in SGCs, a marker of SGC activation, and increased coupling among SGCs, a known component of activated SGCs. Activated SGCs have previously been shown to contribute to pain in other classical neuropathic pain models, suggesting that pain in multiple sclerosis has a peripheral component.

  6. Satellite glial cells in situ within mammalian prevertebral ganglia express K+ channels active at rest potential.

    PubMed

    Gola, M; Niel, J P; Delmas, P; Jacquet, G

    1993-10-01

    Patch-clamp experiments were performed on satellite glial cells wrapped around sympathetic neurons in the rabbit coeliac ganglion. With the cleaning method used, the glial cells could be kept in place and were directly accessible to the patch-clamp pipettes. Whole-cell recordings showed that glial cells had almost ohmic properties. Their resting potential (-79.1 +/- 1.2 mV) was found to be very nearly the same as the K+ reversal potential and approximately 20 mV more negative than that of the neurons they encapsulated. Unitary currents from ionic channels present in the glial membrane were recorded in the cell-attached configuration with pipettes filled with various amounts of K+, Na+ and gluconate. Only K(+)-selective channels with slight inwardly rectifying properties (in the presence of 150 mM [K+]o) were detected. These channels were active (Po = 0.7-0.8) at the cell resting potential. The channel conductance, but not its opening probability, was dependent on the [K+] in the pipette. Cl(-)-selective channels (outwardly rectifying and large conductance channels) were detected in excised patches. The properties of the K+ channels (increased inward current with [K+] and detectable outward current at low [K+]) are well suited for siphoning the K+ released by active neurons.

  7. A single bout of exercise activates skeletal muscle satellite cells during subsequent overnight recovery.

    PubMed

    Snijders, Tim; Verdijk, Lex B; Beelen, Milou; McKay, Bryon R; Parise, Gianni; Kadi, Fawzi; van Loon, Luc J C

    2012-06-01

    Skeletal muscle satellite cell (SC) content has been reported to increase following a single bout of exercise. Data on muscle fibre type-specific SC content and/or SC activation status are presently lacking. The objective of the study was to determine the impact of a single bout of exercise on muscle fibre type-specific SC content and activation status following subsequent overnight recovery. Eight healthy men (age, 20 ± 1 years) performed a single bout of combined endurance- and resistance-type exercise. Muscle biopsies were collected before and immediately after exercise, and following 9 h of postexercise, overnight recovery. Muscle fibre type-specific SC and myonuclear content and SC activation status were determined by immunohistochemical analyses. Satellite cell activation status was assessed by immunohistochemical staining for both Delta-like homologue 1 (DLK1) and Ki-67. Muscle fibre size and fibre area per nucleus were greater in type II compared with type I muscle fibres (P < 0.05). At baseline, no differences were observed in the percentage of SCs staining positive for DLK1 and/or Ki67 between fibre types. No significant changes were observed in SC content following 9 h of postexercise, overnight recovery; however, the percentage of DLK1-positive SCs increased significantly during overnight recovery, from 22 ± 5 to 41 ± 5% and from 24 ± 6 to 51 ± 9% in the type I and II muscle fibres, respectively. No changes were observed in the percentage of Ki-67-positive SCs. A single bout of exercise activates both type I and II skeletal muscle fibre SCs within a single night of postexercise recovery, preceding the subsequent increase in SC content.

  8. mTOR is necessary for proper satellite cell activity and skeletal muscle regeneration

    SciTech Connect

    Zhang, Pengpeng; Liang, Xinrong; Shan, Tizhong; Jiang, Qinyang; Deng, Changyan; Zheng, Rong; Kuang, Shihuan

    2015-07-17

    The serine/threonine kinase mammalian target of rapamycin (mTOR) is a key regulator of protein synthesis, cell proliferation and energy metabolism. As constitutive deletion of Mtor gene results in embryonic lethality, the function of mTOR in muscle stem cells (satellite cells) and skeletal muscle regeneration remains to be determined. In this study, we established a satellite cell specific Mtor conditional knockout (cKO) mouse model by crossing Pax7{sup CreER} and Mtor{sup flox/flox} mice. Skeletal muscle regeneration after injury was severely compromised in the absence of Mtor, indicated by increased number of necrotic myofibers infiltrated by Evans blue dye, and reduced number and size of regenerated myofibers in the Mtor cKO mice compared to wild type (WT) littermates. To dissect the cellular mechanism, we analyzed satellite cell-derived primary myoblasts grown on single myofibers or adhered to culture plates. The Mtor cKO myoblasts exhibited defective proliferation and differentiation kinetics when compared to myoblasts derived from WT littermates. At the mRNA and protein levels, the Mtor cKO myoblasts expressed lower levels of key myogenic determinant genes Pax7, Myf5, Myod, Myog than did the WT myoblasts. These results suggest that mTOR is essential for satellite cell function and skeletal muscle regeneration through controlling the expression of myogenic genes. - Highlights: • Pax7{sup CreER} was used to delete Mtor gene in satellite cells. • Satellite cell specific deletion of Mtor impairs muscle regeneration. • mTOR is necessary for satellite cell proliferation and differentiation. • Deletion of Mtor leads to reduced expression of key myogenic genes.

  9. Mixed lactate and caffeine compound increases satellite cell activity and anabolic signals for muscle hypertrophy.

    PubMed

    Oishi, Yoshimi; Tsukamoto, Hayato; Yokokawa, Takumi; Hirotsu, Keisuke; Shimazu, Mariko; Uchida, Kenji; Tomi, Hironori; Higashida, Kazuhiko; Iwanaka, Nobumasa; Hashimoto, Takeshi

    2015-03-15

    We examined whether a mixed lactate and caffeine compound (LC) could effectively elicit proliferation and differentiation of satellite cells or activate anabolic signals in skeletal muscles. We cultured C2C12 cells with either lactate or LC for 6 h. We found that lactate significantly increased myogenin and follistatin protein levels and phosphorylation of P70S6K while decreasing the levels of myostatin relative to the control. LC significantly increased protein levels of Pax7, MyoD, and Ki67 in addition to myogenin, relative to control. LC also significantly increased follistatin expression relative to control and stimulated phosphorylation of mTOR and P70S6K. In an in vivo study, male F344/DuCrlCrlj rats were assigned to control (Sed, n = 10), exercise (Ex, n = 12), and LC supplementation (LCEx, n = 13) groups. LC was orally administered daily. The LCEx and Ex groups were exercised on a treadmill, running for 30 min at low intensity every other day for 4 wk. The LCEx group experienced a significant increase in the mass of the gastrocnemius (GA) and tibialis anterior (TA) relative to both the Sed and Ex groups. Furthermore, the LCEx group showed a significant increase in the total DNA content of TA compared with the Sed group. The LCEx group experienced a significant increase in myogenin and follistatin expression of GA relative to the Ex group. These results suggest that administration of LC can effectively increase muscle mass concomitant with elevated numbers of myonuclei, even with low-intensity exercise training, via activated satellite cells and anabolic signals.

  10. Satellite glial cells in dorsal root ganglia are activated in streptozotocin-treated rodents.

    PubMed

    Hanani, Menachem; Blum, Erez; Liu, Shuangmei; Peng, Lichao; Liang, Shangdong

    2014-12-01

    Neuropathic pain is a very common complication in diabetes mellitus (DM), and treatment for it is limited. As DM is becoming a global epidemic it is important to understand and treat this problem. The mechanisms of diabetic neuropathic pain are largely obscure. Recent studies have shown that glial cells are important for a variety of neuropathic pain types, and we investigated what are the changes that satellite glial cells (SGCs) in dorsal root ganglia undergo in a DM type 1 model, induced by streptozotocin (STZ) in mice and rats. We carried out immunohistochemical studies to learn about changes in the activation marker glial fibrillary acidic protein (GFAP) in SGCs. We found that after STZ-treatment the number of neurons surrounded with GFAP-positive SGCs in dorsal root ganglia increased 4-fold in mice and 5-fold in rats. Western blotting for GFAP, which was done only on rats because of the larger size of the ganglia, showed an increase of about 2-fold in STZ-treated rats, supporting the immunohistochemical results. These results indicate for the first time that SGCs are activated in rodent models of DM1. As SGC activation appears to contribute to chronic pain, these results suggest that SGCs may participate in the generation and maintenance of diabetic neuropathic pain, and can serve as a potential therapeutic target.

  11. Effect of eccentric contraction on satellite cell activation in human vastus lateralis muscle.

    PubMed

    Imaoka, Yoko; Kawai, Minako; Mori, Futoshi; Miyata, Hirofumi

    2015-09-01

    We compared the time-course of satellite cell (SC) activation between eccentric and concentric contractions in the vastus lateralis (VL) muscle after step exercise. Young adults participated in a 30-min step up/down exercise which mainly involved concentric contractions with the right VL muscle and eccentric contractions with the left VL muscle. The concentric and eccentric contraction phases of the VL muscles were identified by changes in the electromyogram (EMG) and knee joint angle. Biopsy samples were taken from both VL muscles at three time periods: before the exercise and 2 and 5 days after the exercise. We found that the numbers of SCs were significantly increased in the type IIa fibers of the left VL at 2 and 5 days after the exercise. The expression of both hepatocyte growth factor (HGF) and myogenic differentiation 1 (MyoD) mRNA had significantly increased in the left VL at 2 and 5 days after the exercise and in the right VL at 5 days after the exercise. The expression of transient receptor potential canonical (TRPC) 1 mRNA also increased in the left VL at 2 days after exercise. These results indicate that eccentric contraction can effectively activate SC proliferation for up to 5 days after exercise. Similar changes in HGF, MyoD and TRPC1 mRNA expression suggest that HGF/c-Met signal activation through cation influx has a major impact on skeletal muscle SC activation in response to eccentric exercise.

  12. Satellite cell activity is differentially affected by contraction mode in human muscle following a work-matched bout of exercise

    PubMed Central

    Hyldahl, Robert D.; Olson, Ty; Welling, Tyson; Groscost, Logan; Parcell, Allen C.

    2014-01-01

    Optimal repair and adaptation of skeletal muscle is facilitated by resident stem cells (satellite cells). To understand how different exercise modes influence satellite cell dynamics, we measured satellite cell activity in conjunction with markers of muscle damage and inflammation in human skeletal muscle following a single work- and intensity-matched bout of eccentric (ECC) or concentric contractions (CON). Participants completed a single bout of ECC (n = 7) or CON (n = 7) of the knee extensors. A muscle biopsy was obtained before and 24 h after exercise. Functional measures and immunohistochemical analyses were used to determine the extent of muscle damage and indices of satellite cell activity. Cytokine concentrations were measured using a multiplexed magnetic bead assay. Isokinetic peak torque decreased following ECC (p < 0.05) but not CON. Greater histological staining of the damage marker Xin was observed in muscle samples of ECC vs. CON. Tenasin C immunoreactivity increased 15 fold (p < 0.01) following ECC and was unchanged following CON. The inflammatory cytokines interferon gamma-induced protein 10 (IP-10) and monocyte chemotactic protein 1 (MCP-1) increased pre- to post-ECC (4.26 ± 1.4 vs. 10.49 ± 5.8 pg/ml, and 3.06 ± 0.7 vs. 6.25 ± 4.6 pg/ml, respectively; p < 0.05). There was no change in any cytokine post-CON. Satellite cell content increased 27% pre- to post-ECC (0.10 ± 0.031 vs. 0.127 ± 0.041, respectively; p < 0.05). There was no change in satellite cell number in CON (0.099 ± 0.027 vs. 0.102 ± 0.029, respectively). There was no fiber type-specific satellite cell response following either exercise mode. ECC but not CON resulted in an increase in MyoD positive nuclei per myofiber pre- to post-exercise (p < 0.05), but there was no change in MyoD DNA binding activity in either condition. In conclusion, ECC but not CON results in functional and histological evidence of muscle damage that is accompanied by increased satellite cell activity 24 h

  13. mTOR is necessary for proper satellite cell activity and skeletal muscle regeneration.

    PubMed

    Zhang, Pengpeng; Liang, Xinrong; Shan, Tizhong; Jiang, Qinyang; Deng, Changyan; Zheng, Rong; Kuang, Shihuan

    The serine/threonine kinase mammalian target of rapamycin (mTOR) is a key regulator of protein synthesis, cell proliferation and energy metabolism. As constitutive deletion of Mtor gene results in embryonic lethality, the function of mTOR in muscle stem cells (satellite cells) and skeletal muscle regeneration remains to be determined. In this study, we established a satellite cell specific Mtor conditional knockout (cKO) mouse model by crossing Pax7(CreER) and Mtor(flox/flox) mice. Skeletal muscle regeneration after injury was severely compromised in the absence of Mtor, indicated by increased number of necrotic myofibers infiltrated by Evans blue dye, and reduced number and size of regenerated myofibers in the Mtor cKO mice compared to wild type (WT) littermates. To dissect the cellular mechanism, we analyzed satellite cell-derived primary myoblasts grown on single myofibers or adhered to culture plates. The Mtor cKO myoblasts exhibited defective proliferation and differentiation kinetics when compared to myoblasts derived from WT littermates. At the mRNA and protein levels, the Mtor cKO myoblasts expressed lower levels of key myogenic determinant genes Pax7, Myf5, Myod, Myog than did the WT myoblasts. These results suggest that mTOR is essential for satellite cell function and skeletal muscle regeneration through controlling the expression of myogenic genes.

  14. S1P lyase in skeletal muscle regeneration and satellite cell activation: exposing the hidden lyase.

    PubMed

    Saba, Julie D; de la Garza-Rodea, Anabel S

    2013-01-01

    Sphingosine-1-phosphate (S1P) is a bioactive sphingolipid whose actions are essential for many physiological processes including angiogenesis, lymphocyte trafficking and development. In addition, S1P serves as a muscle trophic factor that enables efficient muscle regeneration. This is due in part to S1P's ability to activate quiescent muscle stem cells called satellite cells (SCs) that are needed for muscle repair. However, the molecular mechanism by which S1P activates SCs has not been well understood. Further, strategies for harnessing S1P signaling to recruit SCs for therapeutic benefit have been lacking. S1P is irreversibly catabolized by S1P lyase (SPL), a highly conserved enzyme that catalyzes the cleavage of S1P at carbon bond C(2-3), resulting in formation of hexadecenal and ethanolamine-phosphate. SPL enhances apoptosis through substrate- and product-dependent events, thereby regulating cellular responses to chemotherapy, radiation and ischemia. SPL is undetectable in resting murine skeletal muscle. However, we recently found that SPL is dynamically upregulated in skeletal muscle after injury. SPL upregulation occurred in the context of a tightly orchestrated genetic program that resulted in a transient S1P signal in response to muscle injury. S1P activated quiescent SCs via a sphingosine-1-phosphate receptor 2 (S1P2)/signal transducer and activator of transcription 3 (STAT3)-dependent pathway, thereby facilitating skeletal muscle regeneration. Mdx mice, which serve as a model for muscular dystrophy (MD), exhibited skeletal muscle SPL upregulation and S1P deficiency. Pharmacological SPL inhibition raised skeletal muscle S1P levels, enhanced SC recruitment and improved mdx skeletal muscle regeneration. These findings reveal how S1P can activate SCs and indicate that SPL suppression may provide a therapeutic strategy for myopathies. This article is part of a Special Issue entitled Advances in Lysophospholipid Research.

  15. Skeletal muscle regeneration is delayed by reduction in Xin expression: consequence of impaired satellite cell activation?

    PubMed

    Nissar, Aliyah A; Zemanek, Bart; Labatia, Rita; Atkinson, Daniel J; van der Ven, Peter F M; Fürst, Dieter O; Hawke, Thomas J

    2012-01-01

    Xin is a striated muscle-specific actin-binding protein whose mRNA expression has been observed in damaged skeletal muscle. Here we demonstrate increased Xin protein expression early postinjury (≤ 12 h) and localization primarily to the periphery of damaged myofibers. At 1 day postinjury, Xin is colocalized with MyoD, confirming expression in activated satellite cells (SCs). By 5 days postinjury, Xin is evident in newly regenerated myofibers, with a return to preinjury levels by 14 days of regeneration. To determine whether the increased Xin expression is functionally relevant, tibialis anterior muscles of wild-type mice were infected with Xin-short hairpin RNA (shRNA) adenovirus, whereas the contralateral tibialis anterior received control adenovirus (Control). Four days postinfection, muscles were harvested or injured with cardiotoxin and collected at 3, 5, or 14 days thereafter. When compared with Control, Xin-shRNA infection attenuated muscle regeneration as demonstrated by Myh3 expression and fiber areas. Given the colocalization of Xin and MyoD, we isolated single myofibers from infected muscles to investigate the effect of silencing Xin on SC function. Relative to Control, SC activation, but not proliferation, was significantly impaired in Xin-shRNA-infected muscles. To determine whether Xin affects the G0-G1 transition, cell cycle reentry was assessed on infected C2C12 myoblasts using a methylcellulose assay. No difference in reentry was noted between groups, suggesting that Xin contributes to SC activation by means other than affecting G0-G1 transition. Together these data demonstrate a critical role for Xin in SC activation and reduction in Xin expression results in attenuated skeletal muscle repair.

  16. Adapted physical exercise enhances activation and differentiation potential of satellite cells in the skeletal muscle of old mice.

    PubMed

    Cisterna, Barbara; Giagnacovo, Marzia; Costanzo, Manuela; Fattoretti, Patrizia; Zancanaro, Carlo; Pellicciari, Carlo; Malatesta, Manuela

    2016-05-01

    During ageing, a progressive loss of skeletal muscle mass and a decrease in muscle strength and endurance take place, in the condition termed sarcopenia. The mechanisms of sarcopenia are complex and still unclear; however, it is known that muscle atrophy is associated with a decline in the number and/or efficiency of satellite cells, the main contributors to muscle regeneration. Physical exercise proved beneficial in sarcopenia; however, knowledge of the effect of adapted physical exercise on the myogenic properties of satellite cells in aged muscles is limited. In this study the amount and activation state of satellite cells as well as their proliferation and differentiation potential were assessed in situ by morphology, morphometry and immunocytochemistry at light and transmission electron microscopy on 28-month-old mice submitted to adapted aerobic physical exercise on a treadmill. Sedentary age-matched mice served as controls, and sedentary adult mice were used as a reference for an unperturbed control at an age when the capability of muscle regeneration is still high. The effect of physical exercise in aged muscles was further analysed by comparing the myogenic potential of satellite cells isolated from old running and old sedentary mice using an in vitro system that allows observation of the differentiation process under controlled experimental conditions. The results of this ex vivo and in vitro study demonstrated that adapted physical exercise increases the number and activation of satellite cells as well as their capability to differentiate into structurally and functionally correct myotubes (even though the age-related impairment in myotube formation is not fully reversed): this evidence further supports adapted physical exercise as a powerful, non-pharmacological approach to counteract sarcopenia and the age-related deterioration of satellite cell capabilities even at very advanced age.

  17. Satellite Cells and Skeletal Muscle Regeneration.

    PubMed

    Dumont, Nicolas A; Bentzinger, C Florian; Sincennes, Marie-Claude; Rudnicki, Michael A

    2015-07-01

    Skeletal muscles are essential for vital functions such as movement, postural support, breathing, and thermogenesis. Muscle tissue is largely composed of long, postmitotic multinucleated fibers. The life-long maintenance of muscle tissue is mediated by satellite cells, lying in close proximity to the muscle fibers. Muscle satellite cells are a heterogeneous population with a small subset of muscle stem cells, termed satellite stem cells. Under homeostatic conditions all satellite cells are poised for activation by stimuli such as physical trauma or growth signals. After activation, satellite stem cells undergo symmetric divisions to expand their number or asymmetric divisions to give rise to cohorts of committed satellite cells and thus progenitors. Myogenic progenitors proliferate, and eventually differentiate through fusion with each other or to damaged fibers to reconstitute fiber integrity and function. In the recent years, research has begun to unravel the intrinsic and extrinsic mechanisms controlling satellite cell behavior. Nonetheless, an understanding of the complex cellular and molecular interactions of satellite cells with their dynamic microenvironment remains a major challenge, especially in pathological conditions. The goal of this review is to comprehensively summarize the current knowledge on satellite cell characteristics, functions, and behavior in muscle regeneration and in pathological conditions.

  18. Age-related changes in satellite cell proliferation by compensatory activation in rat diaphragm muscles.

    PubMed

    Kawai, Minako; Saitsu, Kiyokazu; Yamashita, Hiroki; Miyata, Hirofumi

    2012-06-01

    To investigate the age-related changes in satellite cell (SC) proliferation in vivo, we used a compensatory activation (CAC) model of the hemi-diaphragm muscle. Young (2-month), adult (14-month) and old (24-month) rats were randomly divided into control and CAC groups. In the CAC group, denervation surgery in the left hemi-diaphragm was performed to induce CAC of the right hemi-diaphragm. Six days after the surgery, the CAC diaphragm muscle was removed and separated into two blocks for immunohistochemical staining and real time RT-PCR procedures. The number of SCs in type I and IIa fibers were not affected significantly by the CAC in any age groups, but that in type IIx/b fibers was significantly increased in the young and adult groups. As compared to the age-matched control group, the Pax7 mRNA expression level was significantly higher in the young and adult CAC groups, but not in the old CAC group. These results may suggest that the mechanism of SC proliferation in type IIx/b fibers is impaired in aged diaphragm muscles.

  19. Intrinsic and extrinsic mechanisms regulating satellite cell function.

    PubMed

    Dumont, Nicolas A; Wang, Yu Xin; Rudnicki, Michael A

    2015-05-01

    Muscle stem cells, termed satellite cells, are crucial for skeletal muscle growth and regeneration. In healthy adult muscle, satellite cells are quiescent but poised for activation. During muscle regeneration, activated satellite cells transiently re-enter the cell cycle to proliferate and subsequently exit the cell cycle to differentiate or self-renew. Recent studies have demonstrated that satellite cells are heterogeneous and that subpopulations of satellite stem cells are able to perform asymmetric divisions to generate myogenic progenitors or symmetric divisions to expand the satellite cell pool. Thus, a complex balance between extrinsic cues and intrinsic regulatory mechanisms is needed to tightly control satellite cell cycle progression and cell fate determination. Defects in satellite cell regulation or in their niche, as observed in degenerative conditions such as aging, can impair muscle regeneration. Here, we review recent discoveries of the intrinsic and extrinsic factors that regulate satellite cell behaviour in regenerating and degenerating muscles.

  20. PRMT7 Preserves Satellite Cell Regenerative Capacity.

    PubMed

    Blanc, Roméo Sébastien; Vogel, Gillian; Chen, Taiping; Crist, Colin; Richard, Stéphane

    2016-02-16

    Regeneration of skeletal muscle requires the continued presence of quiescent muscle stem cells (satellite cells), which become activated in response to injury. Here, we report that whole-body protein arginine methyltransferase PRMT7(-/-) adult mice and mice conditionally lacking PRMT7 in satellite cells using Pax7-CreERT2 both display a significant reduction in satellite cell function, leading to defects in regenerative capacity upon muscle injury. We show that PRMT7 is preferentially expressed in activated satellite cells and, interestingly, PRMT7-deficient satellite cells undergo cell-cycle arrest and premature cellular senescence. These defects underlie poor satellite cell stem cell capacity to regenerate muscle and self-renew after injury. PRMT7-deficient satellite cells express elevated levels of the CDK inhibitor p21CIP1 and low levels of its repressor, DNMT3b. Restoration of DNMT3b in PRMT7-deficient cells rescues PRMT7-mediated senescence. Our findings define PRMT7 as a regulator of the DNMT3b/p21 axis required to maintain muscle stem cell regenerative capacity.

  1. HDAC4 promotes Pax7-dependent satellite cell activation and muscle regeneration

    PubMed Central

    Choi, Moon-Chang; Ryu, Soyoung; Hao, Rui; Wang, Bin; Kapur, Meghan; Fan, Chen-Ming; Yao, Tso-Pang

    2014-01-01

    During muscle regeneration, the transcription factor Pax7 stimulates the differentiation of satellite cells (SCs) toward the muscle lineage but restricts adipogenesis. Here, we identify HDAC4 as a regulator of Pax7-dependent muscle regeneration. In HDAC4-deficient SCs, the expression of Pax7 and its target genes is reduced. We identify HDAC4-regulated Lix1 as a Pax7 target gene required for SC proliferation. HDAC4 inactivation leads to defective SC proliferation, muscle regeneration, and aberrant lipid accumulation. Further, expression of the brown adipose master regulator Prdm16 and its inhibitory microRNA-133 are also deregulated. Thus, HDAC4 is a novel regulator of Pax7-dependent SC proliferation and potentially fate determination in regenerating muscle. PMID:25205686

  2. Macrophage deficiency in osteopetrotic (op/op) mice inhibits activation of satellite cells and prevents hypertrophy in single soleus fibers.

    PubMed

    Ohira, T; Wang, X D; Ito, T; Kawano, F; Goto, K; Izawa, T; Ohno, H; Kizaki, T; Ohira, Y

    2015-05-15

    Effects of macrophage on the responses of soleus fiber size to hind limb unloading and reloading were studied in osteopetrotic homozygous (op/op) mice with inactivated mutation of macrophage colony-stimulating factor (M-CSF) gene and in wild-type (+/+) and heterozygous (+/op) mice. The basal levels of mitotically active and quiescent satellite cell (-46 and -39% vs. +/+, and -40 and -30% vs. +/op) and myonuclear number (-29% vs. +/+ and -28% vs. +/op) in fibers of op/op mice were significantly less than controls. Fiber length and sarcomere number in op/op were also less than +/+ (-22%) and +/op (-21%) mice. Similar trend was noted in fiber cross-sectional area (CSA, -15% vs. +/+, P = 0.06, and -14% vs. +/op, P = 0.07). The sizes of myonuclear domain, cytoplasmic volume per myonucleus, were identical in all types of mice. The CSA, length, and the whole number of sarcomeres, myonuclei, and mitotically active and quiescent satellite cells, as well as myonuclear domain, in single muscle fibers were decreased after 10 days of unloading in all types of mice, although all of these parameters in +/+ and +/op mice were increased toward the control values after 10 days of reloading. However, none of these levels in op/op mice were recovered. Data suggest that M-CSF and/or macrophages are important to activate satellite cells, which cause increase of myonuclear number during fiber hypertrophy. However, it is unclear why their responses to general growth and reloading after unloading are different.

  3. Plane of nutrition affects growth rate, organ size and skeletal muscle satellite cell activity in newborn calves.

    PubMed

    MacGhee, M E; Bradley, J S; McCoski, S R; Reeg, A M; Ealy, A D; Johnson, S E

    2016-11-18

    Plane of nutrition effects on body, tissue and cellular growth in the neonatal calf are poorly understood. The hypothesis that a low plane of nutrition (LPN) would limit skeletal muscle size by reducing fibre growth and muscle progenitor cell activity was tested. At birth, calves were randomly assigned to either a LPN (20% CP, 20% fat; GE=1.9 Mcal/days) or a high plane of nutrition (HPN; 27% CP, 10% fat, GE = 3.8 Mcal/days) in a 2 × 3 factorial design to test the impact of diet on neonatal calf growth, organ weight and skeletal muscle morphometry with time. Groups of calves (n = 4 or 5) were euthanised at 2, 4 and 8 week of age and organ and empty carcass weights were recorded. Body composition was measured by DXA. Longissimus muscle (LM) fibre cross-sectional area (CSA), fibre/mm(2) and Pax7 were measured by immunohistology. Satellite cells were isolated at each time point and proliferation rates were measured by EdU incorporation. Calves fed a HPN had greater (p < 0.05) BW, ADG and hip height than those fed a LPN for 2, 4 or 8 weeks. HPN calves contained a greater (p < 0.05) percentage of fat tissue than LPN calves. Liver, spleen and thymus weights were less (p < 0.05) in LPN calves than HPN animals. Calves fed HPN had larger (p < 0.05) LM CSA at 8 weeks than LPN fed animals with no differences between the groups in numbers of satellite cells per fibre. Proliferation rates of satellite cells isolated from HPN fed calves were greater (p < 0.05) at 2 weeks than LPN fed animals, which exhibited greater (p < 0.05) proliferation rates at 4 weeks than HPN fed calves. We conclude a LPN diet reduces body growth and organ size and metabolically reprograms satellite cell activity.

  4. Systemic inflammation activates satellite glial cells in the mouse nodose ganglion and alters their functions.

    PubMed

    Feldman-Goriachnik, Rachel; Belzer, Vitali; Hanani, Menachem

    2015-06-23

    Satellite glial cell (SGCs) in trigeminal and dorsal root ganglia are altered structurally and functionally under pathological conditions associated with chronic pain. These changes include reactive gliosis, augmented coupling by gap junctions, and increased responses to ATP via purinergic P2 receptors. Similar information for nodose ganglia (NG), which receive sensory inputs from internal organs via the vagus nerves, is missing. Here, we investigated changes in SGCs in mouse NG after the intraperitoneal administration of lipopolysaccharide (LPS), which induces systemic inflammation. Using calcium imaging we found that SGCs in intact, freshly isolated NG are sensitive to ATP, acting largely via purinergic P2 receptors (mixed P2X and P2Y), with threshold at 0.1 μM. A single systemic injection of LPS (2.5 mg/kg) induced a 6-fold increase in the responses to ATP, largely by augmenting the sensitivity of P2X receptors. Immunohistochemical analysis revealed that at 1-14 days post-LPS injection the expression of glial fibrillary acidic protein in SGCs was 2-3-fold greater than controls. The expression of pannexin 1 channels increased 2-fold at day 7 after LPS injection. Using intracellular labeling we examined dye coupling among SGCs around different neurons, and observed an over 2-fold higher incidence of dye coupling after the induction of inflammation. Incubating the ganglia with ATP increased dye coupling by acting on neuronal P2X receptors, suggesting a role for ATP in the LPS-induced changes. We conclude that inflammation induces prominent changes in SGCs of NG, which might have a role in vagal afferent functions, such as the inflammatory reflex. GLIA 2015.

  5. Selective control of Pax7 expression by TNF-activated p38α/polycomb repressive complex 2 (PRC2) signaling during muscle satellite cell differentiation.

    PubMed

    Mozzetta, Chiara; Consalvi, Silvia; Saccone, Valentina; Forcales, Sonia V; Puri, Pier Lorenzo; Palacios, Daniela

    2011-01-15

    Muscle regeneration relies on adult muscle stem (satellite) cells. Inflammatory cues released within the regenerative microenvironment, such as TNFα, instruct different components of the satellite cell niche toward specialized tasks by regulating specific subsets of genes in each individual cell type. However, how regeneration cues are deciphered and interpreted by the multitude of cell types within the regenerative environment is unknown. We have recently identified an inflammation-activated signaling, consisting of p38α-mediated recruitment of polycomb repressive complex 2 (PRC2) to the Pax7 promoter, in satellite cells. Here we show that p38α-PRC2 regulation of Pax7 expression is restricted to a discrete stage of satellite cell-mediated regeneration. In activated satellite cells, Pax7 locus shows a "bivalent" chromatin signature, with co-existence of H3-K27(3me) and H3-K4(3me), that appears to confer responsiveness to p38α-PRC2 signaling. p38α activation resolves bivalence to H3-K27(3me) which results in Pax7 repression, while p38α blockade promotes Pax7 expression by preventing PRC2-mediated H3-K27(3me) and leading to relative increase in H3-K4(3me). Interestingly, in satellite cell-derived myotubes Pax7 expression cannot be re-induced by p38α blockade, revealing a post-mitotic resistance of Pax7 gene to inflammatory cues. Likewise, in other cell types, such as muscle-derived fibroblasts, Pax7 locus is constitutively repressed by PRC2 and is unresponsive to p38α signaling. Finally, we show that Pax7 repression in embryonic stem cells is not directed by p38α signaling, although it is mediated by PRC2. This evidence indicates a cell type- and differentiation-stage specific control of Pax7 transcription by the p38α-PRC2.

  6. 3D timelapse analysis of muscle satellite cell motility.

    PubMed

    Siegel, Ashley L; Atchison, Kevin; Fisher, Kevin E; Davis, George E; Cornelison, D D W

    2009-10-01

    Skeletal muscle repair and regeneration requires the activity of satellite cells, a population of myogenic stem cells scattered throughout the tissue and activated to proliferate and differentiate in response to myotrauma or disease. While it seems likely that satellite cells would need to navigate local muscle tissue to reach damaged areas, relatively little data on such motility exist, and most studies have been with immortalized cell lines. We find that primary satellite cells are significantly more motile than myoblast cell lines, and that adhesion to laminin promotes primary cell motility more than fourfold over other substrates. Using timelapse videomicroscopy to assess satellite cell motility on single living myofibers, we have identified a requirement for the laminin-binding integrin alpha 7 beta 1 in satellite cell motility, as well as a role for hepatocyte growth factor in promoting directional persistence. The extensive migratory behavior of satellite cells resident on muscle fibers suggests caution when determining, based on fixed specimens, whether adjacent cells are daughters from the same mother cell. We also observed more persistent long-term contact between individual satellite cells than has been previously supposed, potential cell-cell attractive and repulsive interactions, and migration between host myofibers. Based on such activity, we assayed for expression of "pathfinding" cues, and found that satellite cells express multiple guidance ligands and receptors. Together, these data suggest that satellite cell migration in vivo may be more extensive than currently thought, and could be regulated by combinations of signals, including adhesive haptotaxis, soluble factors, and guidance cues.

  7. Numb-deficient satellite cells have regeneration and proliferation defects

    PubMed Central

    George, Rajani M.; Biressi, Stefano; Beres, Brian J.; Rogers, Erik; Mulia, Amanda K.; Allen, Ronald E.; Rawls, Alan; Rando, Thomas A.; Wilson-Rawls, Jeanne

    2013-01-01

    The adaptor protein Numb has been implicated in the switch between cell proliferation and differentiation made by satellite cells during muscle repair. Using two genetic approaches to ablate Numb, we determined that, in its absence, muscle regeneration in response to injury was impaired. Single myofiber cultures demonstrated a lack of satellite cell proliferation in the absence of Numb, and the proliferation defect was confirmed in satellite cell cultures. Quantitative RT-PCR from Numb-deficient satellite cells demonstrated highly up-regulated expression of p21 and Myostatin, both inhibitors of myoblast proliferation. Transfection with Myostatin-specific siRNA rescued the proliferation defect of Numb-deficient satellite cells. Furthermore, overexpression of Numb in satellite cells inhibited Myostatin expression. These data indicate a unique function for Numb during the initial activation and proliferation of satellite cells in response to muscle injury. PMID:24170859

  8. Satellite cells: the architects of skeletal muscle.

    PubMed

    Chang, Natasha C; Rudnicki, Michael A

    2014-01-01

    The outstanding regenerative capacity of skeletal muscle is attributed to the resident muscle stem cell termed satellite cell. Satellite cells are essential for skeletal muscle regeneration as they ultimately provide the myogenic precursors that rebuild damaged muscle tissue. Satellite cells characteristically are a heterogeneous population of stem cells and committed progenitor cells. Delineation of cellular hierarchy and understanding how lineage fate choices are determined within the satellite cell population will be invaluable for the advancement of muscle regenerative therapies.

  9. Sphingosine-1-phosphate enhances satellite cell activation in dystrophic muscles through a S1PR2/STAT3 signaling pathway.

    PubMed

    Loh, Kenneth C; Leong, Weng-In; Carlson, Morgan E; Oskouian, Babak; Kumar, Ashok; Fyrst, Henrik; Zhang, Meng; Proia, Richard L; Hoffman, Eric P; Saba, Julie D

    2012-01-01

    Sphingosine-1-phosphate (S1P) activates a widely expressed family of G protein-coupled receptors, serves as a muscle trophic factor and activates muscle stem cells called satellite cells (SCs) through unknown mechanisms. Here we show that muscle injury induces dynamic changes in S1P signaling and metabolism in vivo. These changes include early and profound induction of the gene encoding the S1P biosynthetic enzyme SphK1, followed by induction of the catabolic enzyme sphingosine phosphate lyase (SPL) 3 days later. These changes correlate with a transient increase in circulating S1P levels after muscle injury. We show a specific requirement for SphK1 to support efficient muscle regeneration and SC proliferation and differentiation. Mdx mice, which serve as a model for muscular dystrophy (MD), were found to be S1P-deficient and exhibited muscle SPL upregulation, suggesting that S1P catabolism is enhanced in dystrophic muscle. Pharmacological SPL inhibition increased muscle S1P levels, improved mdx muscle regeneration and enhanced SC proliferation via S1P receptor 2 (S1PR2)-dependent inhibition of Rac1, thereby activating Signal Transducer and Activator of Transcription 3 (STAT3), a central player in inflammatory signaling. STAT3 activation resulted in p21 and p27 downregulation in a S1PR2-dependent fashion in myoblasts. Our findings suggest that S1P promotes SC progression through the cell cycle by repression of cell cycle inhibitors via S1PR2/STAT3-dependent signaling and that SPL inhibition may provide a therapeutic strategy for MD.

  10. Atrophy, inducible satellite cell activation, and possible denervation of supraspinatus muscle in injured human rotator-cuff muscle.

    PubMed

    Gigliotti, Deanna; Leiter, Jeff R S; Macek, Bryce; Davidson, Michael J; MacDonald, Peter B; Anderson, Judy E

    2015-09-15

    The high frequency of poor outcome and chronic pain after surgical repair of shoulder rotator-cuff injury (RCI) prompted this study to explore the potential to amplify muscle regeneration using nitric oxide (NO)-based treatment. After preoperative magnetic resonance imaging (MRI), biopsies of supraspinatus and ipsilateral deltoid (as a control) were collected during reparative surgery for RCI. Muscle fiber diameter, the pattern of neuromuscular junctions observed with alpha-bungarotoxin staining, and the γ:ε subunit ratio of acetylcholine receptors in Western blots were examined in tandem with experiments to determine the in vitro responsiveness of muscle satellite cells to activation (indicated by uptake of bromodeoxyuridine, BrdU) by the NO-donor drug, isosorbide dinitrate (ISDN). Consistent with MRI findings of supraspinatus atrophy (reduced occupation ratio and tangent sign), fiber diameter was lower in supraspinatus than in deltoid. ISDN induced a significant increase over baseline (up to 1.8-fold), in the proportion of BrdU+ (activated) Pax7+ satellite cells in supraspinatus, but not in deltoid, after 40 h in culture. The novel application of denervation indices revealed a trend for supraspinatus muscle to have a higher γ:ε subunit ratio than deltoid (P = 0.13); this ratio inversely with both occupancy ratio (P < 0.05) and the proportion of clusters at neuromuscular junctions (P = 0.05). Results implicate possible supraspinatus denervation in RCI and suggest NO-donor treatment has potential to promote growth in atrophic supraspinatus muscle after RCI and improve functional outcome.

  11. P2Y1 Receptor Activation of the TRPV4 Ion Channel Enhances Purinergic Signaling in Satellite Glial Cells*

    PubMed Central

    Rajasekhar, Pradeep; Poole, Daniel P.; Liedtke, Wolfgang; Bunnett, Nigel W.; Veldhuis, Nicholas A.

    2015-01-01

    Transient receptor potential (TRP) ion channels of peripheral sensory pathways are important mediators of pain, itch, and neurogenic inflammation. They are expressed by primary sensory neurons and by glial cells in the central nervous system, but their expression and function in satellite glial cells (SGCs) of sensory ganglia have not been explored. SGCs tightly ensheath neurons of sensory ganglia and can regulate neuronal excitability in pain and inflammatory states. Using a modified dissociation protocol, we isolated neurons with attached SGCs from dorsal root ganglia of mice. SGCs, which were identified by expression of immunoreactive Kir4.1 and glutamine synthetase, were closely associated with neurons, identified using the pan-neuronal marker NeuN. A subpopulation of SGCs expressed immunoreactive TRP vanilloid 4 (TRPV4) and responded to the TRPV4-selective agonist GSK1016790A by an influx of Ca2+ ions. SGCs did not express functional TRPV1, TRPV3, or TRP ankyrin 1 channels. Responses to GSK1016790A were abolished by the TRPV4 antagonist HC067047 and were absent in SGCs from Trpv4−/− mice. The P2Y1-selective agonist 2-methylthio-ADP increased [Ca2+]i in SGCs, and responses were prevented by the P2Y1-selective antagonist MRS2500. P2Y1 receptor-mediated responses were enhanced in TRPV4-expressing SGCs and HEK293 cells, suggesting that P2Y1 couples to and activates TRPV4. PKC inhibitors prevented P2Y1 receptor activation of TRPV4. Our results provide the first evidence for expression of TRPV4 in SGCs and demonstrate that TRPV4 is a purinergic receptor-operated channel in SGCs of sensory ganglia. PMID:26475857

  12. Satellite Cells and the Muscle Stem Cell Niche

    PubMed Central

    Yin, Hang; Price, Feodor

    2013-01-01

    Adult skeletal muscle in mammals is a stable tissue under normal circumstances but has remarkable ability to repair after injury. Skeletal muscle regeneration is a highly orchestrated process involving the activation of various cellular and molecular responses. As skeletal muscle stem cells, satellite cells play an indispensible role in this process. The self-renewing proliferation of satellite cells not only maintains the stem cell population but also provides numerous myogenic cells, which proliferate, differentiate, fuse, and lead to new myofiber formation and reconstitution of a functional contractile apparatus. The complex behavior of satellite cells during skeletal muscle regeneration is tightly regulated through the dynamic interplay between intrinsic factors within satellite cells and extrinsic factors constituting the muscle stem cell niche/microenvironment. For the last half century, the advance of molecular biology, cell biology, and genetics has greatly improved our understanding of skeletal muscle biology. Here, we review some recent advances, with focuses on functions of satellite cells and their niche during the process of skeletal muscle regeneration. PMID:23303905

  13. Satellite cells in human skeletal muscle plasticity.

    PubMed

    Snijders, Tim; Nederveen, Joshua P; McKay, Bryon R; Joanisse, Sophie; Verdijk, Lex B; van Loon, Luc J C; Parise, Gianni

    2015-01-01

    Skeletal muscle satellite cells are considered to play a crucial role in muscle fiber maintenance, repair and remodeling. Our knowledge of the role of satellite cells in muscle fiber adaptation has traditionally relied on in vitro cell and in vivo animal models. Over the past decade, a genuine effort has been made to translate these results to humans under physiological conditions. Findings from in vivo human studies suggest that satellite cells play a key role in skeletal muscle fiber repair/remodeling in response to exercise. Mounting evidence indicates that aging has a profound impact on the regulation of satellite cells in human skeletal muscle. Yet, the precise role of satellite cells in the development of muscle fiber atrophy with age remains unresolved. This review seeks to integrate recent results from in vivo human studies on satellite cell function in muscle fiber repair/remodeling in the wider context of satellite cell biology whose literature is largely based on animal and cell models.

  14. Insulin-like growth factor-I extends in vitro replicative life span of skeletal muscle satellite cells by enhancing G1/S cell cycle progression via the activation of phosphatidylinositol 3'-kinase/Akt signaling pathway

    NASA Technical Reports Server (NTRS)

    Chakravarthy, M. V.; Abraha, T. W.; Schwartz, R. J.; Fiorotto, M. L.; Booth, F. W.

    2000-01-01

    Interest is growing in methods to extend replicative life span of non-immortalized stem cells. Using the insulin-like growth factor I (IGF-I) transgenic mouse in which the IGF-I transgene is expressed during skeletal muscle development and maturation prior to isolation and during culture of satellite cells (the myogenic stem cells of mature skeletal muscle fibers) as a model system, we elucidated the underlying molecular mechanisms of IGF-I-mediated enhancement of proliferative potential of these cells. Satellite cells from IGF-I transgenic muscles achieved at least five additional population doublings above the maximum that was attained by wild type satellite cells. This IGF-I-induced increase in proliferative potential was mediated via activation of the phosphatidylinositol 3'-kinase/Akt pathway, independent of mitogen-activated protein kinase activity, facilitating G(1)/S cell cycle progression via a down-regulation of p27(Kip1). Adenovirally mediated ectopic overexpression of p27(Kip1) in exponentially growing IGF-I transgenic satellite cells reversed the increase in cyclin E-cdk2 kinase activity, pRb phosphorylation, and cyclin A protein abundance, thereby implicating an important role for p27(Kip1) in promoting satellite cell senescence. These observations provide a more complete dissection of molecular events by which increased local expression of a growth factor in mature skeletal muscle fibers extends replicative life span of primary stem cells than previously known.

  15. Nitric oxide-proton stimulation of trigeminal ganglion neurons increases mitogen-activated protein kinase and phosphatase expression in neurons and satellite glial cells.

    PubMed

    Freeman, S E; Patil, V V; Durham, P L

    2008-12-02

    Elevated nitric oxide (NO) and proton levels in synovial fluid are implicated in joint pathology. However, signaling pathways stimulated by these molecules that mediate inflammation and pain in the temporomandibular joint (TMJ) have not been investigated. The goal of this study was to determine the effect of NO-proton stimulation of rat trigeminal neurons on the in vivo expression of mitogen-activated protein kinases (MAPKs) and phosphatases (MKPs) in trigeminal ganglion neurons and satellite glial cells. Low levels of the active MAPKs extracellular signal-regulated kinase (ERK), Jun amino-terminal kinase (JNK), and p38 were localized in the cytosol of neurons and satellite glial cells in unstimulated animals. However, increased levels of active ERK and p38, but not JNK, were detected in the cytosol and nucleus of V3 neurons and satellite glial cells 15 min and 2 h following bilateral TMJ injections of an NO donor diluted in pH 5.5 medium. While ERK levels returned to near basal levels 24 h after stimulation, p38 levels remained significantly elevated. In contrast to MKP-2 and MKP-3 levels that were barely detectable in neurons or satellite glial cells, MKP-1 staining was readily observed in satellite glial cells in ganglia from unstimulated animals. However, neuronal and satellite glial cell staining for MKP-1, MKP-2, and MKP-3 was significantly increased in response to NO-protons. Increased active ERK and p38 levels as well as elevated MKP levels were also detected in neurons and satellite glial cells located in V2 and V1 regions of the ganglion. Our data provide evidence that NO-proton stimulation of V3 neurons results in temporal and spatial changes in expression of active ERK and p38 and MKPs in all regions of the ganglion. We propose that in trigeminal ganglia these cellular events, which are involved in peripheral sensitization as well as control of inflammatory and nociceptive responses, may play a role in TMJ pathology.

  16. Myogenic skeletal muscle satellite cells communicate by tunnelling nanotubes.

    PubMed

    Tavi, Pasi; Korhonen, Topi; Hänninen, Sandra L; Bruton, Joseph D; Lööf, Sara; Simon, Andras; Westerblad, Håkan

    2010-05-01

    Quiescent satellite cells sit on the surface of the muscle fibres under the basal lamina and are activated by a variety of stimuli to disengage, divide and differentiate into myoblasts that can regenerate or repair muscle fibres. Satellite cells adopt their parent's fibre type and must have some means of communication with the parent fibre. The mechanisms behind this communication are not known. We show here that satellite cells form dynamic connections with muscle fibres and other satellite cells by F-actin based tunnelling nanotubes (TNTs). Our results show that TNTs readily develop between satellite cells and muscle fibres. Once developed, TNTs permit transport of intracellular material, and even cellular organelles such as mitochondria between the muscle fibre and satellite cells. The onset of satellite cell differentiation markers Pax-7 and MyoD expression was slower in satellite cells cultured in the absence than in the presence of muscle cells. Furthermore physical contact between myofibre and satellite cell progeny is required to maintain subtype identity. Our data establish that TNTs constitute an integral part of myogenic cell communication and that physical cellular interaction control myogenic cell fate determination.

  17. Functional Overload Enhances Satellite Cell Properties in Skeletal Muscle.

    PubMed

    Fujimaki, Shin; Machida, Masanao; Wakabayashi, Tamami; Asashima, Makoto; Takemasa, Tohru; Kuwabara, Tomoko

    2016-01-01

    Skeletal muscle represents a plentiful and accessible source of adult stem cells. Skeletal-muscle-derived stem cells, termed satellite cells, play essential roles in postnatal growth, maintenance, repair, and regeneration of skeletal muscle. Although it is well known that the number of satellite cells increases following physical exercise, functional alterations in satellite cells such as proliferative capacity and differentiation efficiency following exercise and their molecular mechanisms remain unclear. Here, we found that functional overload, which is widely used to model resistance exercise, causes skeletal muscle hypertrophy and converts satellite cells from quiescent state to activated state. Our analysis showed that functional overload induces the expression of MyoD in satellite cells and enhances the proliferative capacity and differentiation potential of these cells. The changes in satellite cell properties coincided with the inactivation of Notch signaling and the activation of Wnt signaling and likely involve modulation by transcription factors of the Sox family. These results indicate the effects of resistance exercise on the regulation of satellite cells and provide insight into the molecular mechanism of satellite cell activation following physical exercise.

  18. The role of satellite cells in muscle hypertrophy.

    PubMed

    Blaauw, Bert; Reggiani, Carlo

    2014-02-01

    The role of satellite cells in muscle hypertrophy has long been a debated issue. In the late 1980s it was shown that proteins remain close to the myonucleus responsible for its synthesis, giving rise to the idea of a nuclear domain. This, together with the observation that during various models of muscle hypertrophy there is an activation of the muscle stem cells, i.e. satellite cells, lead to the idea that satellite cell activation is required for muscle hypertrophy. Thus, satellite cells are not only responsible for muscle repair and regeneration, but also for hypertrophic growth. Further support for this line of thinking was obtained after studies showing that irradiation of skeletal muscle, and therefore elimination of all satellite cells, completely prevented overload-induced hypertrophy. Recently however, using different transgenic approaches, it has become clear that muscle hypertrophy can occur without a contribution of satellite cells, even though in most situations of muscle hypertrophy satellite cells are activated. In this review we will discuss the contribution of satellite cells, and other muscle-resident stem cells, to muscle hypertrophy both in mice as well as in humans.

  19. Enceladus: An Active Cryovolcanic Satellite

    NASA Technical Reports Server (NTRS)

    Spencer, J. R.; Barr, Amy C.; Esposito, L. W.; Helfenstein, P.; Ingersoll, A. P.; Jaumann, R.; McKay, C. P.; Nimmo, F.; Waite, J. H.

    2009-01-01

    Enceladus is one of the most remarkable satellites in the solar system, as revealed by Cassini's detection of active plumes erupting from warm fractures near its south pole. This discovery makes Enceladus the only icy satellite known to exhibit ongoing internally driven geological activity. The activity is presumably powered by tidal heating maintained by Enceladus 2:1 mean-motion resonance with Dione, but many questions remain. For instance, it appears difficult or impossible to maintain the currently observed radiated power (probably at least 6 GW) in steady state. It is also not clear how Enceladus first entered its current self-maintaining warm and dissipative state initial heating from non-tidal sources is probably required. There are also many unanswered questions about Enceladus interior. The silicate fraction inferred from its density of 1.68 g per cubic centimeter is probably differentiated into a core, though we have only indirect evidence for differentiation. Above the core there is probably a global or regional water layer, inferred from several models of tidal heating, and an ice shell thick enough to support the 1 kilometer amplitude topography seen on Enceladus. It is possible that dissipation is largely localized beneath the south polar region. Enceladus surface geology, ranging from moderately cratered terrain to the virtually crater-free active south polar region, is highly diverse, tectonically complex, and remarkably symmetrical about the rotation axis and the direction to Saturn. South polar activity is concentrated along the four tiger stripe fractures, which radiate heat at temperatures up to at least 167 K and are the source of multiple plumes ejecting 200 kilograms per second of H2O vapor along with significant N2 (or C2H4), CO2, CH4, NH3, and higher-mass hydrocarbons. The escaping gas maintains Saturn's neutral gas torus, and the plumes also eject a large number of micron-sized H2O ice grains that populate Saturn's E-ring. The mechanism

  20. Regulation of Satellite Cell Function in Sarcopenia

    PubMed Central

    Alway, Stephen E.; Myers, Matthew J.; Mohamed, Junaith S.

    2014-01-01

    The mechanisms contributing to sarcopenia include reduced satellite cell (myogenic stem cell) function that is impacted by the environment (niche) of these cells. Satellite cell function is affected by oxidative stress, which is elevated in aged muscles, and this along with changes in largely unknown systemic factors, likely contribute to the manner in which satellite cells respond to stressors such as exercise, disuse, or rehabilitation in sarcopenic muscles. Nutritional intervention provides one therapeutic strategy to improve the satellite cell niche and systemic factors, with the goal of improving satellite cell function in aging muscles. Although many elderly persons consume various nutraceuticals with the hope of improving health, most of these compounds have not been thoroughly tested, and the impacts that they might have on sarcopenia and satellite cell function are not clear. This review discusses data pertaining to the satellite cell responses and function in aging skeletal muscle, and the impact that three compounds: resveratrol, green tea catechins, and β-Hydroxy-β-methylbutyrate have on regulating satellite cell function and therefore contributing to reducing sarcopenia or improving muscle mass after disuse in aging. The data suggest that these nutraceutical compounds improve satellite cell function during rehabilitative loading in animal models of aging after disuse (i.e., muscle regeneration). While these compounds have not been rigorously tested in humans, the data from animal models of aging provide a strong basis for conducting additional focused work to determine if these or other nutraceuticals can offset the muscle losses, or improve regeneration in sarcopenic muscles of older humans via improving satellite cell function. PMID:25295003

  1. Satellite cells in human skeletal muscle plasticity

    PubMed Central

    Snijders, Tim; Nederveen, Joshua P.; McKay, Bryon R.; Joanisse, Sophie; Verdijk, Lex B.; van Loon, Luc J. C.; Parise, Gianni

    2015-01-01

    Skeletal muscle satellite cells are considered to play a crucial role in muscle fiber maintenance, repair and remodeling. Our knowledge of the role of satellite cells in muscle fiber adaptation has traditionally relied on in vitro cell and in vivo animal models. Over the past decade, a genuine effort has been made to translate these results to humans under physiological conditions. Findings from in vivo human studies suggest that satellite cells play a key role in skeletal muscle fiber repair/remodeling in response to exercise. Mounting evidence indicates that aging has a profound impact on the regulation of satellite cells in human skeletal muscle. Yet, the precise role of satellite cells in the development of muscle fiber atrophy with age remains unresolved. This review seeks to integrate recent results from in vivo human studies on satellite cell function in muscle fiber repair/remodeling in the wider context of satellite cell biology whose literature is largely based on animal and cell models. PMID:26557092

  2. Role of the mTORC1 complex in satellite cell activation by RNA-induced mitochondrial restoration: dual control of cyclin D1 through microRNAs.

    PubMed

    Jash, Sukanta; Dhar, Gunjan; Ghosh, Utpalendu; Adhya, Samit

    2014-10-01

    During myogenesis, satellite stem cells (SCs) are induced to proliferate and differentiate to myogenic precursors. The role of energy sensors such as the AMP-activated protein kinase (AMPK) and the mammalian Target of Rapamycin (mTOR) in SC activation is unclear. We previously observed that upregulation of ATP through RNA-mediated mitochondrial restoration (MR) accelerates SC activation following skeletal muscle injury. We show here that during regeneration, the AMPK-CRTC2-CREB and Raptor-mTORC-4EBP1 pathways were rapidly activated. The phosho-CRTC2-CREB complex was essential for myogenesis and activated transcription of the critical cell cycle regulator cyclin D1 (Ccnd1). Knockdown (KD) of either mTORC or its subunit Raptor delayed SC activation without influencing the differentiation program. KD of 4EBP1 had no effect on SC activation but enhanced myofiber size. mTORC1 positively regulated Ccnd1 translation but destabilized Ccnd1 mRNA. These antithetical effects of mTORC1 were mediated by two microRNAs (miRs) targeted to the 3' untranslated region (UTR) of Ccnd1 mRNA: miR-1 was downregulated in mTORC-KD muscle, and depletion of miR-1 resulted in increased levels of mRNA without any effect on Ccnd1 protein. In contrast, miR-26a was upregulated upon mTORC depletion, while anti-miR-26a oligonucleotide specifically stimulated Ccnd1 protein expression. Thus, mTORC may act as a timer of satellite cell proliferation during myogenesis.

  3. Muscle Satellite Cells: Exploring the Basic Biology to Rule Them

    PubMed Central

    Almeida, Camila F.; Fernandes, Stephanie A.; Ribeiro Junior, Antonio F.; Vainzof, Mariz

    2016-01-01

    Adult skeletal muscle is a postmitotic tissue with an enormous capacity to regenerate upon injury. This is accomplished by resident stem cells, named satellite cells, which were identified more than 50 years ago. Since their discovery, many researchers have been concentrating efforts to answer questions about their origin and role in muscle development, the way they contribute to muscle regeneration, and their potential to cell-based therapies. Satellite cells are maintained in a quiescent state and upon requirement are activated, proliferating, and fusing with other cells to form or repair myofibers. In addition, they are able to self-renew and replenish the stem pool. Every phase of satellite cell activity is highly regulated and orchestrated by many molecules and signaling pathways; the elucidation of players and mechanisms involved in satellite cell biology is of extreme importance, being the first step to expose the crucial points that could be modulated to extract the optimal response from these cells in therapeutic strategies. Here, we review the basic aspects about satellite cells biology and briefly discuss recent findings about therapeutic attempts, trying to raise questions about how basic biology could provide a solid scaffold to more successful use of these cells in clinics. PMID:27042182

  4. Extrinsic regulation of satellite cell specification.

    PubMed

    Bentzinger, C Florian; von Maltzahn, Julia; Rudnicki, Michael A

    2010-08-26

    Cellular commitment during vertebrate embryogenesis is controlled by an interplay of intrinsic regulators and morphogenetic signals. These mechanisms recruit a subset of cells in the developing organism to become the ancestors of skeletal muscle. Signals that control progression through the myogenic lineage converge on a battery of hierarchically organized transcription factors which modulate the cells to either remain in a primitive state or allow their commitment and differentiation into skeletal muscle fibers. A small population of cells will retain a largely unspecified state throughout development. Such stem cells, in conjunction with more committed myogenic progenitors, form a heterogeneous population that colonizes adult skeletal muscle as satellite cells. The satellite cell pool is responsible for the remarkable regenerative capacity of skeletal muscle. Similar to their counterparts during embryonic development, satellite cells are capable of self-renewal and can give rise to myogenic progeny. Impaired satellite cell homeostasis has been associated with numerous muscular disorders. Due to intense research efforts in the past two decades, the complex biology of muscle stem cells has now revealed some of its secrets and new avenues for the development of therapeutic molecules have emerged. In the present review we focus on the extrinsic mechanisms that control self-renewal, specification and differentiation of satellite cells and their significance for the development of biologic drugs.

  5. Notch signaling deficiency underlies age-dependent depletion of satellite cells in muscular dystrophy.

    PubMed

    Jiang, Chunhui; Wen, Yefei; Kuroda, Kazuki; Hannon, Kevin; Rudnicki, Michael A; Kuang, Shihuan

    2014-08-01

    Duchenne muscular dystrophy (DMD) is a devastating disease characterized by muscle wasting, loss of mobility and death in early adulthood. Satellite cells are muscle-resident stem cells responsible for the repair and regeneration of damaged muscles. One pathological feature of DMD is the progressive depletion of satellite cells, leading to the failure of muscle repair. Here, we attempted to explore the molecular mechanisms underlying satellite cell ablation in the dystrophin mutant mdx mouse, a well-established model for DMD. Initial muscle degeneration activates satellite cells, resulting in increased satellite cell number in young mdx mice. This is followed by rapid loss of satellite cells with age due to the reduced self-renewal ability of mdx satellite cells. In addition, satellite cell composition is altered even in young mdx mice, with significant reductions in the abundance of non-committed (Pax7+ and Myf5-) satellite cells. Using a Notch-reporter mouse, we found that the mdx satellite cells have reduced activation of Notch signaling, which has been shown to be necessary to maintain satellite cell quiescence and self-renewal. Concomitantly, the expression of Notch1, Notch3, Jag1, Hey1 and HeyL are reduced in the mdx primary myoblast. Finally, we established a mouse model to constitutively activate Notch signaling in satellite cells, and show that Notch activation is sufficient to rescue the self-renewal deficiencies of mdx satellite cells. These results demonstrate that Notch signaling is essential for maintaining the satellite cell pool and that its deficiency leads to depletion of satellite cells in DMD.

  6. Using Cell Phones From Satellites

    NASA Technical Reports Server (NTRS)

    Horan, Stephen

    2000-01-01

    During the past several years, an interest has grown in using commercial telecommunications techniques to supply Telemetry and Command (T&C) services. Recently, the National Aeronautics and Space Administration (NASA) Space Operations Management Office (SOMO) has outlined plans to utilize satellite-based telecommunications services to support space operations in space missions over the next several decades. NASA currently obtains the bulk of its telecommunications services for earth-orbiting satellites via the existing government-owned and controlled Space Network (SN) system. This system consists of the constellation of Tracking and Data Relay Satellites (TDRS) in Geostationary Earth Orbit (GEO) and the associated ground terminals and communications intrastructure. This system is valuable and effective for scientific satellites costing over one million dollars. However, for smaller satellites, this system becomes problematic due to the cost of transponders and support infrastructure. The nominal transponders for using the TDRS cannot be obtained for a cost in dollars, and size, weight, or power that the 3 Corner Satellite project can afford. For these types of nanosatellite missions, alternatives that fit the mission cost and satellite profiles are needed. In particular, low-cost access using existing commercial infrastructure would be useful to mission planners. In particular, the ability to obtain low data rate T&C services would be especially valuable. The nanosatellites generally have low T&C requirements and therefore would benefit from using commercial services that could operate in the 2400 bps - 9600 bps range, especially if contact times longer than the 5 - 10 minute ground station passes could be found.

  7. Stimulation with monochromatic green light during incubation alters satellite cell mitotic activity and gene expression in relation to embryonic and posthatch muscle growth of broiler chickens.

    PubMed

    Zhang, L; Zhang, H J; Wang, J; Wu, S G; Qiao, X; Yue, H Y; Yao, J H; Qi, G H

    2014-01-01

    Previous studies showed that monochromatic green light stimuli during embryogenesis accelerated posthatch body weight (BW) and pectoral muscle growth of broilers. In this experiment, we further investigated the morphological and molecular basis of this phenomenon. Fertile broiler eggs (Arbor Acres, n=880) were pre-weighed and randomly assigned to 1 of the 2 incubation treatment groups: (1) dark condition (control group), and (2) monochromatic green light group (560 nm). The monochromatic lighting systems sourced from light-emitting diode lamps and were equalized at the intensity of 15 lx at eggshell level. The dark condition was set as a commercial control from day 1 until hatching. After hatch, 120 male 1-day-old chicks from each group were housed under incandescent white light with an intensity of 30 lx at bird-head level. No effects of light stimuli during embryogenesis on hatching time, hatchability, hatching weight and bird mortality during the feeding trial period were observed in the present study. Compared with the dark condition, the BW, pectoral muscle weight and myofiber cross-sectional areas were significantly greater on 7-day-old chicks incubated under green light. Green light also increased the satellite cell mitotic activity of pectoral muscle on 1- and 3-day-old birds. In addition, green light upregulated MyoD, myogenin and myostatin mRNA expression in late embryos and/ or newly hatched chicks. These data suggest that stimulation with monochromatic green light during incubation promote muscle growth by enhancing proliferation and differentiation of satellite cells in late embryonic and newly hatched stages. Higher expression of myostatin may ultimately help prevent excessive proliferation and differentiation of satellite cells in birds incubated under green light.

  8. Muscle Satellite Cell Protein Teneurin-4 Regulates Differentiation During Muscle Regeneration.

    PubMed

    Ishii, Kana; Suzuki, Nobuharu; Mabuchi, Yo; Ito, Naoki; Kikura, Naomi; Fukada, So-Ichiro; Okano, Hideyuki; Takeda, Shin'ichi; Akazawa, Chihiro

    2015-10-01

    Satellite cells are maintained in an undifferentiated quiescent state, but during muscle regeneration they acquire an activated stage, and initiate to proliferate and differentiate as myoblasts. The transmembrane protein teneurin-4 (Ten-4) is specifically expressed in the quiescent satellite cells; however, its cellular and molecular functions remain unknown. We therefore aimed to elucidate the function of Ten-4 in muscle satellite cells. In the tibialis anterior (TA) muscle of Ten-4-deficient mice, the number and the size of myofibers, as well as the population of satellite cells, were reduced with/without induction of muscle regeneration. Furthermore, we found an accelerated activation of satellite cells in the regenerated Ten-4-deficient TA muscle. The cell culture analysis using primary satellite cells showed that Ten-4 suppressed the progression of myogenic differentiation. Together, our findings revealed that Ten-4 functions as a crucial player in maintaining the quiescence of muscle satellite cells.

  9. TAK1 modulates satellite stem cell homeostasis and skeletal muscle repair.

    PubMed

    Ogura, Yuji; Hindi, Sajedah M; Sato, Shuichi; Xiong, Guangyan; Akira, Shizuo; Kumar, Ashok

    2015-12-09

    Satellite cells are resident adult stem cells that are required for regeneration of skeletal muscle. However, signalling mechanisms that regulate satellite cell function are less understood. Here we demonstrate that transforming growth factor-β-activated kinase 1 (TAK1) is important in satellite stem cell homeostasis and function. Inactivation of TAK1 in satellite cells inhibits muscle regeneration in adult mice. TAK1 is essential for satellite cell proliferation and its inactivation causes precocious differentiation. Moreover, TAK1-deficient satellite cells exhibit increased oxidative stress and undergo spontaneous cell death, primarily through necroptosis. TAK1 is required for the activation of NF-κB and JNK in satellite cells. Forced activation of NF-κB improves survival and proliferation of TAK1-deficient satellite cells. Furthermore, TAK1-mediated activation of JNK is essential to prevent oxidative stress and precocious differentiation of satellite cells. Collectively, our study suggests that TAK1 is required for maintaining the pool of satellite stem cells and for regenerative myogenesis.

  10. The PERK arm of the unfolded protein response regulates satellite cell-mediated skeletal muscle regeneration.

    PubMed

    Xiong, Guangyan; Hindi, Sajedah M; Mann, Aman K; Gallot, Yann S; Bohnert, Kyle R; Cavener, Douglas R; Whittemore, Scott R; Kumar, Ashok

    2017-03-23

    Regeneration of skeletal muscle in adults is mediated by satellite stem cells. Accumulation of misfolded proteins triggers endoplasmic reticulum stress that leads to unfolded protein response (UPR). The UPR is relayed to the cell through the activation of PERK, IRE1/XBP1, and ATF6. Here, we demonstrate that levels of PERK and IRE1 are increased in satellite cells upon muscle injury. Inhibition of PERK, but not the IRE1 arm of the UPR in satellite cells inhibits myofiber regeneration in adult mice. PERK is essential for the survival and differentiation of activated satellite cells into the myogenic lineage. Deletion of PERK causes hyper-activation of p38 MAPK during myogenesis. Blocking p38 MAPK activity improves the survival and differentiation of PERK-deficient satellite cells in vitro and muscle formation in vivo. Collectively, our results suggest that the PERK arm of the UPR plays a pivotal role in the regulation of satellite cell homeostasis during regenerative myogenesis.

  11. Acute morphine activates satellite glial cells and up-regulates IL-1β in dorsal root ganglia in mice via matrix metalloprotease-9

    PubMed Central

    2012-01-01

    Background Activation of spinal cord glial cells such as microglia and astrocytes has been shown to regulate chronic opioid-induced antinociceptive tolerance and hyperalgesia, due to spinal up-regulation of the proinflammatory cytokines such as interleukin-1 beta (IL-1β). Matrix metalloprotease-9 (MMP-9) has been implicated in IL-1β activation in neuropathic pain. However, it is unclear whether acute opioid treatment can activate glial cells in the peripheral nervous system. We examined acute morphine-induced activation of satellite glial cells (SGCs) and up-regulation of IL-1β in dorsal root ganglia (DRGs), and further investigated the involvement of MMP-9 in these opioid-induced peripheral changes. Results Subcutaneous morphine injection (10 mg/kg) induced robust peripheral glial responses, as evidenced by increased GFAP expression in DRGs but not in spinal cords. The acute morphine-induced GFAP expression is transient, peaking at 2 h and declining after 3 h. Acute morphine treatment also increased IL-1β immunoreactivity in SGCs and IL-1β activation in DRGs. MMP-9 and GFAP are expressed in DRG neurons and SGCs, respectively. Confocal analysis revealed a close proximity of MMP-9 and GFAP immunostaining. Importantly, morphine-induced DRG up-regulation of GFAP expression and IL-1β activation was abolished after Mmp9 deletion or naloxone pre-treatment. Finally, intrathecal injections of IL-1β-selective siRNA not only reduced DRG IL-1β expression but also prolonged acute morphine-induced analgesia. Conclusions Acute morphine induces opioid receptors- and MMP-9-dependent up-regulation of GFAP expression and IL-1β activation in SGCs of DRGs. MMP-9 could mask and shorten morphine analgesia via peripheral neuron-glial interactions. Targeting peripheral glial activation might prolong acute opioid analgesia. PMID:22439811

  12. Satellite cell proliferation in adult skeletal muscle

    NASA Technical Reports Server (NTRS)

    Booth, Frank W. (Inventor); Thomason, Donald B. (Inventor); Morrison, Paul R. (Inventor); Stancel, George M. (Inventor)

    1995-01-01

    Novel methods of retroviral-mediated gene transfer for the in vivo corporation and stable expression of eukaryotic or prokaryotic foreign genes in tissues of living animals is described. More specifically, methods of incorporating foreign genes into mitotically active cells are disclosed. The constitutive and stable expression of E. coli .beta.-galactosidase gene under the promoter control of the Moloney murine leukemia virus long terminal repeat is employed as a particularly preferred embodiment, by way of example, establishes the model upon which the incorporation of a foreign gene into a mitotically-active living eukaryotic tissue is based. Use of the described methods in therapeutic treatments for genetic diseases, such as those muscular degenerative diseases, is also presented. In muscle tissue, the described processes result in genetically-altered satellite cells which proliferate daughter myoblasts which preferentially fuse to form a single undamaged muscle fiber replacing damaged muscle tissue in a treated animal. The retroviral vector, by way of example, includes a dystrophin gene construct for use in treating muscular dystrophy. The present invention also comprises an experimental model utilizable in the study of the physiological regulation of skeletal muscle gene expression in intact animals.

  13. Satellite microglia show spontaneous electrical activity that is uncorrelated with activity of the attached neuron.

    PubMed

    Wogram, Emile; Wendt, Stefan; Matyash, Marina; Pivneva, Tatyana; Draguhn, Andreas; Kettenmann, Helmut

    2016-06-01

    Microglia are innate immune cells of the brain. We have studied a subpopulation of microglia, called satellite microglia. This cell type is defined by a close morphological soma-to-soma association with a neuron, indicative of a direct functional interaction. Indeed, ultrastructural analysis revealed closely attached plasma membranes of satellite microglia and neurons. However, we found no apparent morphological specializations of the contact, and biocytin injection into satellite microglia showed no dye-coupling with the apposed neurons or any other cell. Likewise, evoked local field potentials or action potentials and postsynaptic potentials of the associated neuron did not lead to any transmembrane currents or non-capacitive changes in the membrane potential of the satellite microglia in the cortex and hippocampus. Both satellite and non-satellite microglia, however, showed spontaneous transient membrane depolarizations that were not correlated with neuronal activity. These events could be divided into fast-rising and slow-rising depolarizations, which showed different characteristics in satellite and non-satellite microglia. Fast-rising and slow-rising potentials differed with regard to voltage dependence. The frequency of these events was not affected by the application of tetrodotoxin, but the fast-rising event frequency decreased after application of GABA. We conclude that microglia show spontaneous electrical activity that is uncorrelated with the activity of adjacent neurons.

  14. Isolation, Culture and Identification of Porcine Skeletal Muscle Satellite Cells.

    PubMed

    Li, Bo-Jiang; Li, Ping-Hua; Huang, Rui-Hua; Sun, Wen-Xing; Wang, Han; Li, Qi-Fa; Chen, Jie; Wu, Wang-Jun; Liu, Hong-Lin

    2015-08-01

    The objective of this study was to establish the optimum protocol for the isolation and culture of porcine muscle satellite cells. Mononuclear muscle satellite cells are a kind of adult stem cell, which is located between the basal lamina and sarcolemma of muscle fibers and is the primary source of myogenic precursor cells in postnatal muscle. Muscle satellite cells are a useful model to investigate the mechanisms of muscle growth and development. Although the isolation and culture protocols of muscle satellite cells in some species (e.g. mouse) have been established successfully, the culture system for porcine muscle satellite cells is very limited. In this study, we optimized the isolation procedure of porcine muscle satellite cells and elaborated the isolation and culture process in detail. Furthermore, we characterized the porcine muscle satellite cells using the immunofluorecence. Our study provides a reference for the isolation of porcine muscle satellite cells and will be useful for studying the molecular mechanisms in these cells.

  15. Multicolour Optical Photometry of Active Geostationary Satellites

    NASA Astrophysics Data System (ADS)

    Jolley, A.; Wade, G.; Bedard, D.

    Although broadband photometry has been used to infer information about artificial satellites since soon after the launch of Sputnik 1, the development of photometric techniques for non-resolved space object identification or characterisation has been hampered by the large number of variables involved. Many individual studies, and some long ongoing experiments, have used costly metre-class telescopes to obtain data despite other experiments demonstrating that much more flexible and affordable small aperture telescopes may be suitable for the task. In addition, due to the highly time consuming and weather dependent nature of obtaining photometric observations, many studies have suffered from data sets of limited size, or relied upon simulations to support their claims. With this in mind, an experiment was conducted with the aim of determining the utility of small aperture telescopes for conducting broadband photometry of satellites for the purpose of non-resolved space object identification and characterisation. A 14 inch Celestron CG-14 telescope was used to gain multiple night-long, high temporal resolution data sets of six active geostationary satellites. The results of the experiment cast doubt on the efficacy of some of the previous approaches to obtaining and analysing photometric data. It was discovered that geostationary satellite lightcurves can vary to a greater degree than has generally been recognised, and colour ratios vary considerably with changes in the illumination/observation geometry, making it difficult to use colour for satellite discrimination. Evidence was also detected of variations in the spectral energy distribution of sunlight reflected off satellite surface materials, which could have implications for surface material characterisation and techniques that aim to separate satellite body and solar panel contributions to the total observed spectra.

  16. Sphingosine-1-phosphate receptor 3 influences cell cycle progression in muscle satellite cells.

    PubMed

    Fortier, Mathieu; Figeac, Nicolas; White, Robert B; Knopp, Paul; Zammit, Peter S

    2013-10-15

    Skeletal muscle retains a resident stem cell population called satellite cells, which are mitotically quiescent in mature muscle, but can be activated to produce myoblast progeny for muscle homeostasis, hypertrophy and repair. We have previously shown that satellite cell activation is partially controlled by the bioactive phospholipid, sphingosine-1-phosphate, and that S1P biosynthesis is required for muscle regeneration. Here we investigate the role of sphingosine-1-phosphate receptor 3 (S1PR3) in regulating murine satellite cell function. S1PR3 levels were high in quiescent myogenic cells before falling during entry into cell cycle. Retrovirally-mediated constitutive expression of S1PR3 led to suppressed cell cycle progression in satellite cells, but did not overtly affect the myogenic program. Conversely, satellite cells isolated from S1PR3-null mice exhibited enhanced proliferation ex-vivo. In vivo, acute cardiotoxin-induced muscle regeneration was enhanced in S1PR3-null mice, with bigger muscle fibres compared to control mice. Importantly, genetically deleting S1PR3 in the mdx mouse model of Duchenne muscular dystrophy produced a less severe muscle dystrophic phenotype, than when signalling though S1PR3 was operational. In conclusion, signalling though S1PR3 suppresses cell cycle progression to regulate function in muscle satellite cells.

  17. Myogenic Potential of Canine Craniofacial Satellite Cells

    PubMed Central

    La Rovere, Rita Maria Laura; Quattrocelli, Mattia; Pietrangelo, Tiziana; Di Filippo, Ester Sara; Maccatrozzo, Lisa; Cassano, Marco; Mascarello, Francesco; Barthélémy, Inès; Blot, Stephane; Sampaolesi, Maurilio; Fulle, Stefania

    2014-01-01

    The skeletal fibers have different embryological origin; the extraocular and jaw-closer muscles develop from prechordal mesoderm while the limb and trunk muscles from somites. These different origins characterize also the adult muscle stem cells, known as satellite cells (SCs) and responsible for the fiber growth and regeneration. The physiological properties of presomitic SCs and their epigenetics are poorly studied despite their peculiar characteristics to preserve muscle integrity during chronic muscle degeneration. Here, we isolated SCs from canine somitic [somite-derived muscle (SDM): vastus lateralis, rectus abdominis, gluteus superficialis, biceps femoris, psoas] and presomitic [pre-somite-derived muscle (PSDM): lateral rectus, temporalis, and retractor bulbi] muscles as myogenic progenitor cells from young and old animals. In addition, SDM and PSDM-SCs were obtained also from golden retrievers affected by muscular dystrophy (GRMD). We characterized the lifespan, the myogenic potential and functions, and oxidative stress of both somitic and presomitic SCs with the aim to reveal differences with aging and between healthy and dystrophic animals. The different proliferation rate was consistent with higher telomerase activity in PSDM-SCs compared to SDM-SCs, although restricted at early passages. SDM-SCs express early (Pax7, MyoD) and late (myosin heavy chain, myogenin) myogenic markers differently from PSDM-SCs resulting in a more efficient and faster cell differentiation. Taken together, our results showed that PSDM-SCs elicit a stronger stem cell phenotype compared to SDM ones. Finally, myomiR expression profile reveals a unique epigenetic signature in GRMD SCs and miR-206, highly expressed in dystrophic SCs, seems to play a critical role in muscle degeneration. Thus, miR-206 could represent a potential target for novel therapeutic approaches. PMID:24860499

  18. Roles of Notch1 Signaling in Regulating Satellite Cell Fates Choices and Postnatal Skeletal Myogenesis.

    PubMed

    Shan, Tizhong; Xu, Ziye; Wu, Weiche; Liu, Jiaqi; Wang, Yizhen

    2016-12-12

    Adult skeletal muscle stem cells, also called satellite cells, are indispensable for the growth, maintenance, and regeneration of the postnatal skeletal muscle. Satellite cells, predominantly quiescent in mature resting muscles, are activated after skeletal muscle injury or degeneration. Notch1 signaling is an evolutionarily conserved pathway that plays crucial roles in satellite cells homeostasis and postnatal skeletal myogenesis and regeneration. Activation of Notch1 signaling promotes the muscle satellite cells quiescence and proliferation, but inhibits differentiation of muscle satellite cells. Notably, the new roles of Notch1 signaling during late-stage of skeletal myogenesis including in post-differentiation myocytes and post-fusion myotubes have been recently reported. Here, we mainly review and discuss the regulatory roles of Notch1 in regulating satellite cell fates choices and skeletal myogenesis. This article is protected by copyright. All rights reserved.

  19. Isolation and Culture of Satellite Cells from Mouse Skeletal Muscle.

    PubMed

    Musarò, Antonio; Carosio, Silvia

    2017-01-01

    Skeletal muscle tissue is characterized by a population of quiescent mononucleated myoblasts, localized between the basal lamina and sarcolemma of myofibers, known as satellite cells. Satellite cells play a pivotal role in muscle homeostasis and are the major source of myogenic precursors in mammalian muscle regeneration.This chapter describes protocols for isolation and culturing satellite cells isolated from mouse skeletal muscles. The classical procedure, which will be discussed extensively in this chapter, involves the enzymatic dissociation of skeletal muscles, while the alternative method involves isolation of satellite cells from isolated myofibers in which the satellite cells remain in their in situ position underneath the myofiber basal lamina.In particular, we discuss the technical aspect of satellite cell isolation, the methods necessary to enrich the satellite cell fraction and the culture conditions that optimize proliferation and myotube formation of mouse satellite cells.

  20. On involvement of transcription factors nuclear factor kappa-light-chain-enhancer of activated B cells, activator protein-1 and signal transducer and activator of transcription-3 in photodynamic therapy-induced death of crayfish neurons and satellite glial cells

    NASA Astrophysics Data System (ADS)

    Berezhnaya, Elena; Neginskaya, Marya; Kovaleva, Vera; Sharifulina, Svetlana; Ischenko, Irina; Komandirov, Maxim; Rudkovskii, Mikhail; Uzdensky, Anatoly B.

    2015-07-01

    Photodynamic therapy (PDT) is currently used in the treatment of brain tumors. However, not only malignant cells but also neighboring normal neurons and glial cells are damaged during PDT. In order to study the potential role of transcription factors-nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), activator protein (AP-1), and signal transducer and activator of transcription-3 (STAT-3)-in photodynamic injury of normal neurons and glia, we photosensitized the isolated crayfish mechanoreceptor consisting of a single sensory neuron enveloped by glial cells. Application of different inhibitors and activators showed that transcription factors NF-κB (inhibitors caffeic acid phenethyl ester and parthenolide, activator betulinic acid), AP-1 (inhibitor SR11302), and STAT-3 (inhibitors stattic and cucurbitacine) influenced PDT-induced death and survival of neurons and glial cells in different ways. These experiments indicated involvement of NF-κB in PDT-induced necrosis of neurons and apoptosis of glial cells. However, in glial cells, it played the antinecrotic role. AP-1 was not involved in PDT-induced necrosis of neurons and glia, but mediated glial apoptosis. STAT-3 was involved in PDT-induced apoptosis of glial cells and necrosis of neurons and glia. Therefore, signaling pathways that regulate cell death and survival in neurons and glial cells are different. Using various inhibitors or activators of transcription factors, one can differently influence the sensitivity and resistance of neurons and glial cells to PDT.

  1. Satellite cell dysfunction and impaired IGF-1 signaling cause CKD-induced muscle atrophy.

    PubMed

    Zhang, Liping; Wang, Xiaonan H; Wang, Huiling; Du, Jie; Mitch, William E

    2010-03-01

    Muscle wasting in chronic kidney disease (CKD) begins with impaired insulin/IGF-1 signaling, causing abnormal protein metabolism. In certain models of muscle atrophy, reduced satellite cell function contributes to atrophy, but how CKD affects satellite cell function is unknown. Here, we found that isolated satellite cells from mice with CKD had less MyoD, the master switch of satellite cell activation, and suppressed myotube formation compared with control mice. In vivo, CKD delayed the regeneration of injured muscle and decreased MyoD and myogenin expression, suggesting that CKD impairs proliferation and differentiation of satellite cells. In isolated satellite cells from control mice, IGF-1 increased the expression of myogenic genes through an Akt-dependent pathway. CKD impaired Akt phosphorylation in satellite cells after muscle injury. To test whether impaired IGF-1 signaling could be responsible for decreased satellite cell function in CKD, we created an inducible IGF-1 receptor knockout mouse and found impaired satellite cell function and muscle regeneration. In addition, both CKD and IGF-1 receptor knockout mice developed fibrosis in regenerating muscles. Taken together, impaired IGF-1 signaling in CKD not only leads to abnormal protein metabolism in muscle but also impairs satellite cell function and promotes fibrosis in regenerating muscle. These signaling pathways may hold potential therapeutic targets to reduce CKD-related muscle wasting.

  2. Spectrometric Characterization of Active Geosynchronous Satellites

    NASA Astrophysics Data System (ADS)

    Bedard, D.; Monin, D.; Scott, R.; Wade, G.

    2012-09-01

    Spectrometric characterization of artificial space objects for the purposes of Space Situational Awareness (SSA) has demonstrated great potential since this technique was first reported at this conference over a decade ago. Yet, much scientific work remains to be done before this tool can be used reliably in an operational context. For example, a detailed study of the impacts of a dynamic illumination-object-sensor geometry during individual spectrometric observations has yet to be described. A thorough understanding of this last problem is considered critical if reflectance spectroscopy will be used to characterize active low Earth orbiting spacecraft, in which the Sun-object-sensor geometry varies considerably over the course of a few seconds, or to study space debris that have uncontrolled and varying attitude. It is with the above questions in mind that two observation campaigns were conducted. The first consisted in using small-aperture telescopes to obtain multi-color photometric light curves of active geosynchronous satellites over a wide range of phase angles. The second observation campaign was conducted at the Dominion Astrophysical Observatory (DAO) using the 1.8-metre Plaskett telescope and its Cassegrain spectrograph. The objective of this experiment was to gather time-resolved spectrometric measurements of active geosynchronous satellites as a function of phase angle. This class of satellites was selected because their attitude is controlled and can be estimated to a high level of confidence. This paper presents the two observation campaigns and provides a summary of the key results of this experiment.

  3. Notch1-mediated signaling regulates proliferation of porcine satellite cells (PSCs).

    PubMed

    Qin, Lili; Xu, Jian; Wu, Zhenfang; Zhang, Zhe; Li, Jiaqi; Wang, Chong; Long, Qiaoming

    2013-02-01

    Notch signaling is an evolutionarily conserved cell-cell communication mechanism involved in the regulation of cell proliferation, differentiation and fate decisions of mammalian cells. In the present study, we investigated the possible requirement for Notch signaling in the proliferation and differentiation of porcine satellite cells. We show that Notch1, 2 and 3 are expressed in cultured porcine satellite cells. Knock-down of NOTCH1, but not NOTCH2 and NOTCH3, decreases the proliferation of porcine satellite cells. In contrast, enhancement of NOTCH1 expression via treatment of porcine satellite cells with recombinant NF-κB increases the proliferation of porcine satellite cells. The alteration of porcine satellite cell proliferation is associated with significant changes in the expression of cell cycle related genes (cyclin B1, D1, D2, E1 and p21), myogenic regulatory factors (MyoD and myogenin) and the Notch effector Hes5. In addition, alteration of Notch1 expression in porcine satellite cells causes changes in the expression of GSK3β-3. Taken together, these findings suggest that of the four notch-related genes, Notch1is likely to be required for regulating the proliferation and therefore the maintenance of porcine satellite cells in vivo, and do so through activation of the Notch effector gene Hes5.

  4. Post-transcriptional regulation of satellite cell quiescence by TTP-mediated mRNA decay

    PubMed Central

    Hausburg, Melissa A; Doles, Jason D; Clement, Sandra L; Cadwallader, Adam B; Hall, Monica N; Blackshear, Perry J; Lykke-Andersen, Jens; Olwin, Bradley B

    2015-01-01

    Skeletal muscle satellite cells in their niche are quiescent and upon muscle injury, exit quiescence, proliferate to repair muscle tissue, and self-renew to replenish the satellite cell population. To understand the mechanisms involved in maintaining satellite cell quiescence, we identified gene transcripts that were differentially expressed during satellite cell activation following muscle injury. Transcripts encoding RNA binding proteins were among the most significantly changed and included the mRNA decay factor Tristetraprolin. Tristetraprolin promotes the decay of MyoD mRNA, which encodes a transcriptional regulator of myogenic commitment, via binding to the MyoD mRNA 3′ untranslated region. Upon satellite cell activation, p38α/β MAPK phosphorylates MAPKAP2 and inactivates Tristetraprolin, stabilizing MyoD mRNA. Satellite cell specific knockdown of Tristetraprolin precociously activates satellite cells in vivo, enabling MyoD accumulation, differentiation and cell fusion into myofibers. Regulation of mRNAs by Tristetraprolin appears to function as one of several critical post-transcriptional regulatory mechanisms controlling satellite cell homeostasis. DOI: http://dx.doi.org/10.7554/eLife.03390.001 PMID:25815583

  5. Donor satellite cell engraftment is significantly augmented when the host niche is preserved and endogenous satellite cells are incapacitated.

    PubMed

    Boldrin, Luisa; Neal, Alice; Zammit, Peter S; Muntoni, Francesco; Morgan, Jennifer E

    2012-09-01

    Stem cell transplantation is already in clinical practice for certain genetic diseases and is a promising therapy for dystrophic muscle. We used the mdx mouse model of Duchenne muscular dystrophy to investigate the effect of the host satellite cell niche on the contribution of donor muscle stem cells (satellite cells) to muscle regeneration. We found that incapacitation of the host satellite cells and preservation of the muscle niche promote donor satellite cell contribution to muscle regeneration and functional reconstitution of the satellite cell compartment. But, if the host niche is not promptly refilled, or is filled by competent host satellite cells, it becomes nonfunctional and donor engraftment is negligible. Application of this regimen to aged host muscles also promotes efficient regeneration from aged donor satellite cells. In contrast, if the niche is destroyed, yet host satellite cells remain proliferation-competent, donor-derived engraftment is trivial. Thus preservation of the satellite cell niche, concomitant with functional impairment of the majority of satellite cells within dystrophic human muscles, may improve the efficiency of stem cell therapy.

  6. Synergist Ablation as a Rodent Model to Study Satellite Cell Dynamics in Adult Skeletal Muscle.

    PubMed

    Kirby, Tyler J; McCarthy, John J; Peterson, Charlotte A; Fry, Christopher S

    2016-01-01

    In adult skeletal muscles, satellite cells are the primary myogenic stem cells involved in myogenesis. Normally, they remain in a quiescent state until activated by a stimulus, after which they proliferate, differentiate, and fuse into an existing myofiber or form a de novo myofiber. To study satellite cell dynamics in adult murine models, most studies utilize regeneration models in which the muscle is severely damaged and requires the participation from satellite cells in order to repair. Here, we describe a model to study satellite cell behavior in muscle hypertrophy that is independent of muscle regeneration.Synergist ablation surgery involves the surgical removal of the gastrocnemius and soleus muscles resulting in functional overload of the remaining plantaris muscle. This functional overload results in myofiber hypertrophy, as well as the activation, proliferation, and fusion of satellite cells into the myofibers. Within 2 weeks of functional overload, satellite cell content increases approximately 275 %, an increase that is accompanied with a ~60 % increase in the number of myonuclei. Therefore, this can be used as an alternative model to study satellite cell behavior in adulthood that is different from regeneration, and capable of revealing new satellite cell functions in regulating muscle adaptation.

  7. Notch Signaling Rescues Loss of Satellite Cells Lacking Pax7 and Promotes Brown Adipogenic Differentiation

    PubMed Central

    Pasut, Alessandra; Chang, Natasha C.; Rodriguez, Uxia Gurriaran; Faulkes, Sharlene; Yin, Hang; Lacaria, Melanie; Ming, Hong; Rudnicki, Michael A.

    2016-01-01

    Summary Pax7 is a nodal transcription factor that is essential for regulating the maintenance, expansion, and myogenic identity of satellite cells during both neonatal and adult myogenesis. Deletion of Pax7 results in loss of satellite cells and impaired muscle regeneration. Here we show that ectopic expression of the constitutively active intracellular domain of Notch1 (NICD1) rescues the loss of Pax7-deficient satellite cells and restores their proliferative potential. Strikingly NICD1-expressing satellite cells do not undergo myogenic differentiation and instead acquire a brown adipogenic fate both in vivo and in vitro. NICD-expressing Pax7-/- satellite cells fail to upregulate MyoD and instead express the brown adipogenic marker PRDM16. Overall these results show that Notch1 activation compensates for the loss of Pax7 in the quiescent state and acts as a molecular switch to promote brown adipogenesis in adult skeletal muscle. PMID:27346341

  8. Notch Signaling Rescues Loss of Satellite Cells Lacking Pax7 and Promotes Brown Adipogenic Differentiation.

    PubMed

    Pasut, Alessandra; Chang, Natasha C; Rodriguez, Uxia Gurriaran; Faulkes, Sharlene; Yin, Hang; Lacaria, Melanie; Ming, Hong; Rudnicki, Michael A

    2016-07-12

    Pax7 is a nodal transcription factor that is essential for regulating the maintenance, expansion, and myogenic identity of satellite cells during both neonatal and adult myogenesis. Deletion of Pax7 results in loss of satellite cells and impaired muscle regeneration. Here, we show that ectopic expression of the constitutively active intracellular domain of Notch1 (NICD1) rescues the loss of Pax7-deficient satellite cells and restores their proliferative potential. Strikingly NICD1-expressing satellite cells do not undergo myogenic differentiation and instead acquire a brown adipogenic fate both in vivo and in vitro. NICD-expressing Pax7(-/-) satellite cells fail to upregulate MyoD and instead express the brown adipogenic marker PRDM16. Overall, these results show that Notch1 activation compensates for the loss of Pax7 in the quiescent state and acts as a molecular switch to promote brown adipogenesis in adult skeletal muscle.

  9. beta-Catenin promotes self-renewal of skeletal-muscle satellite cells.

    PubMed

    Perez-Ruiz, Ana; Ono, Yusuke; Gnocchi, Viola F; Zammit, Peter S

    2008-05-01

    Satellite cells are the resident stem cells of adult skeletal muscle. As with all stem cells, how the choice between self-renewal or differentiation is controlled is central to understanding their function. Here, we have explored the role of beta-catenin in determining the fate of myogenic satellite cells. Satellite cells express beta-catenin, and expression is maintained as they activate and undergo proliferation. Constitutive retroviral-driven expression of wild-type or stabilised beta-catenin results in more satellite cells expressing Pax7 without any MyoD -- therefore, adopting the self-renewal pathway, with fewer cells undergoing myogenic differentiation. Similarly, preventing the degradation of endogenous beta-catenin by inhibiting GSK3beta activity also results in more Pax7-positive-MyoD-negative (Pax7(+)MyoD(-)) satellite-cell progeny. Consistent with these observations, downregulation of beta-catenin using small interfering RNA (siRNA) reduced the proportion of satellite cells that express Pax7 and augmented myogenic differentiation after mitogen withdrawal. Since a dominant-negative version of beta-catenin had the same effect as silencing beta-catenin using specific siRNA, beta-catenin promotes self-renewal via transcriptional control of target genes. Thus, beta-catenin signalling in proliferating satellite cells directs these cells towards the self-renewal pathway and, so, contributes to the maintenance of this stem-cell pool in adult skeletal muscle.

  10. Satellite Cells in Muscular Dystrophy - Lost in Polarity.

    PubMed

    Chang, Natasha C; Chevalier, Fabien P; Rudnicki, Michael A

    2016-06-01

    Recent findings employing the mdx mouse model for Duchenne muscular dystrophy (DMD) have revealed that muscle satellite stem cells play a direct role in contributing to disease etiology and progression of DMD, the most common and severe form of muscular dystrophy. Lack of dystrophin expression in DMD has critical consequences in satellite cells including an inability to establish cell polarity, abrogation of asymmetric satellite stem-cell divisions, and failure to enter the myogenic program. Thus, muscle wasting in dystrophic mice is not only caused by myofiber fragility but is exacerbated by intrinsic satellite cell dysfunction leading to impaired regeneration. Despite intense research and clinical efforts, there is still no effective cure for DMD. In this review we highlight recent research advances in DMD and discuss the current state of treatment and, importantly, how we can incorporate satellite cell-targeted therapeutic strategies to correct satellite cell dysfunction in DMD.

  11. Methods for Observing and Quantifying Muscle Satellite Cell Motility and Invasion In Vitro.

    PubMed

    Lund, Dane K; McAnulty, Patrick; Siegel, Ashley L; Cornelison, Ddw

    2017-01-01

    Motility and/or chemotaxis of satellite cells has been suggested or observed in multiple in vitro and in vivo contexts. Satellite cell motility also affects the efficiency of muscle regeneration, particularly in the context of engrafted exogenous cells. Consequently, there is keen interest in determining what cell-autonomous and environmental factors influence satellite cell motility and chemotaxis in vitro and in vivo. In addition, the ability of activated satellite cells to relocate in vivo would suggest that they must be able to invade and transit through the extracellular matrix (ECM), which is supported by studies in which alteration or addition of matrix metalloprotease (MMP) activity enhanced the spread of engrafted satellite cells. However, despite its potential importance, analysis of satellite cell motility or invasion quantitatively even in an in vitro setting can be difficult; one of the most powerful techniques for overcoming these difficulties is timelapse microscopy. Identification and longitudinal evaluation of individual cells over time permits not only quantification of variations in motility due to intrinsic or extrinsic factors, it permits observation and analysis of other (frequently unsuspected) cellular activities as well. We describe here three protocols developed in our group for quantitatively analyzing satellite cell motility over time in two dimensions on purified ECM substrates, in three dimensions on a living myofiber, and in three dimensions through an artificial matrix.

  12. Advanced Solar Cells for Satellite Power Systems

    NASA Technical Reports Server (NTRS)

    Flood, Dennis J.; Weinberg, Irving

    1994-01-01

    The multiple natures of today's space missions with regard to operational lifetime, orbital environment, cost and size of spacecraft, to name just a few, present such a broad range of performance requirements to be met by the solar array that no single design can suffice to meet them all. The result is a demand for development of specialized solar cell types that help to optimize overall satellite performance within a specified cost range for any given space mission. Historically, space solar array performance has been optimized for a given mission by tailoring the features of silicon solar cells to account for the orbital environment and average operating conditions expected during the mission. It has become necessary to turn to entirely new photovoltaic materials and device designs to meet the requirements of future missions, both in the near and far term. This paper will outline some of the mission drivers and resulting performance requirements that must be met by advanced solar cells, and provide an overview of some of the advanced cell technologies under development to meet them. The discussion will include high efficiency, radiation hard single junction cells; monolithic and mechanically stacked multiple bandgap cells; and thin film cells.

  13. Hesr1 and Hesr3 are essential to generate undifferentiated quiescent satellite cells and to maintain satellite cell numbers.

    PubMed

    Fukada, So-ichiro; Yamaguchi, Masahiko; Kokubo, Hiroki; Ogawa, Ryo; Uezumi, Akiyoshi; Yoneda, Tomohiro; Matev, Miroslav M; Motohashi, Norio; Ito, Takahito; Zolkiewska, Anna; Johnson, Randy L; Saga, Yumiko; Miyagoe-Suzuki, Yuko; Tsujikawa, Kazutake; Takeda, Shin'ichi; Yamamoto, Hiroshi

    2011-11-01

    Satellite cells, which are skeletal muscle stem cells, divide to provide new myonuclei to growing muscle fibers during postnatal development, and then are maintained in an undifferentiated quiescent state in adult skeletal muscle. This state is considered to be essential for the maintenance of satellite cells, but their molecular regulation is unknown. We show that Hesr1 (Hey1) and Hesr3 (Heyl) (which are known Notch target genes) are expressed simultaneously in skeletal muscle only in satellite cells. In Hesr1 and Hesr3 single-knockout mice, no obvious abnormalities of satellite cells or muscle regenerative potentials are observed. However, the generation of undifferentiated quiescent satellite cells is impaired during postnatal development in Hesr1/3 double-knockout mice. As a result, myogenic (MyoD and myogenin) and proliferative (Ki67) proteins are expressed in adult satellite cells. Consistent with the in vivo results, Hesr1/3-null myoblasts generate very few Pax7(+) MyoD(-) undifferentiated cells in vitro. Furthermore, the satellite cell number gradually decreases in Hesr1/3 double-knockout mice even after it has stabilized in control mice, and an age-dependent regeneration defect is observed. In vivo results suggest that premature differentiation, but not cell death, is the reason for the reduced number of satellite cells in Hesr1/3 double-knockout mice. These results indicate that Hesr1 and Hesr3 are essential for the generation of adult satellite cells and for the maintenance of skeletal muscle homeostasis.

  14. Cripto regulates skeletal muscle regeneration and modulates satellite cell determination by antagonizing myostatin.

    PubMed

    Guardiola, Ombretta; Lafuste, Peggy; Brunelli, Silvia; Iaconis, Salvatore; Touvier, Thierry; Mourikis, Philippos; De Bock, Katrien; Lonardo, Enza; Andolfi, Gennaro; Bouché, Ann; Liguori, Giovanna L; Shen, Michael M; Tajbakhsh, Shahragim; Cossu, Giulio; Carmeliet, Peter; Minchiotti, Gabriella

    2012-11-20

    Skeletal muscle regeneration mainly depends on satellite cells, a population of resident muscle stem cells. However, our understanding of the molecular mechanisms underlying satellite cell activation is still largely undefined. Here, we show that Cripto, a regulator of early embryogenesis, is a novel regulator of muscle regeneration and satellite cell progression toward the myogenic lineage. Conditional inactivation of cripto in adult satellite cells compromises skeletal muscle regeneration, whereas gain of function of Cripto accelerates regeneration, leading to muscle hypertrophy. Moreover, we provide evidence that Cripto modulates myogenic cell determination and promotes proliferation by antagonizing the TGF-β ligand myostatin. Our data provide unique insights into the molecular and cellular basis of Cripto activity in skeletal muscle regeneration and raise previously undescribed implications for stem cell biology and regenerative medicine.

  15. Hepatocyte growth factor plays a dual role in regulating skeletal muscle satellite cell proliferation and differentiation.

    PubMed

    Gal-Levi, R; Leshem, Y; Aoki, S; Nakamura, T; Halevy, O

    1998-03-12

    The role of hepatocyte growth factor (HGF) and its receptor, c-met, in proliferation and differentiation of satellite cells was studied in primary cultures of chicken skeletal muscle satellite cells and a myogenic C2 cell line. HGF mRNA was expressed mainly in the myotubes of both cultures. The addition of conditioned medium derived from those cultures had a scattering effect on the canine kidney epithelial cell line, MDCK. In contrast, c-met mRNA levels decreased during cell differentiation of C2 and primary satellite cells. Application of exogenous HGF to chicken myoblasts resulted in their enhanced DNA synthesis. Among several growth factors, HGF was the first to induce DNA synthesis in quiescent satellite cells, thereby driving them into the cell cycle. Ectopic expression of chicken HGF in primary satellite cells suppressed the activation of muscle-regulatory gene reporter constructs MCK-CAT, MRF4-CAT, MEF2-CAT and 4Rtk-CAT, as well as the gene expression of MyoD and myogenin, and MHC protein expression. Ectopic MyoD reversed HGF's inhibitory effect on MCK transactivation. These data suggest that HGF inhibits cell differentiation by inhibiting the activity of basic helix-loop-helix (bHLH)/E protein heterodimers, thus inhibiting myogenic determination factor activity and subsequent muscle-specific protein expression. During muscle growth and regeneration, HGF plays a dual role in satellite-cell myogenesis, affecting both the proliferation and differentiation of these cells in a paracrine fashion.

  16. Hypoxia simultaneously alters satellite cell-mediated angiogenesis and hepatocyte growth factor expression.

    PubMed

    Flann, K L; Rathbone, C R; Cole, L C; Liu, X; Allen, R E; Rhoads, R P

    2014-05-01

    Skeletal muscle regeneration is a multifaceted process requiring the spatial and temporal coordination of myogenesis as well as angiogenesis. Hepatocyte growth factor (HGF) plays a pivotal role in myogenesis by activating satellite cells (SC) in regenerating muscle and likely plays a role as a contributor to revascularization. Moreover, repair of a functional blood supply is critical to ameliorate tissue ischemia and restore skeletal muscle function, however effects of hypoxia on satellite cell-mediated angiogenesis remain unclear. The objective of this study was to examine the role of HGF and effect of hypoxia on the capacity of satellite cells to promote angiogenesis. To characterize the role of HGF, a microvascular fragment (MVF) culture model coupled with satellite cell conditioned media (CM) was employed. The activity of HGF was specifically blocked in SC CM reducing sprout length compared to control CM. In contrast, MVF sprout number did not differ between control or HGF-deficient SC CM media. Next, we cultured MVF in the presence of CM from satellite cells exposed to normoxic (20% O2 ) or hypoxic (1% O2 ) conditions. Hypoxic CM recapitulated a MVF angiogenic response identical to HGF deficient satellite cell CM. Hypoxic conditions increased satellite cell HIF-1α protein abundance and VEGF mRNA abundance but decreased HGF mRNA abundance compared to normoxic satellite cells. Consistent with reduced HGF gene expression, HGF promoter activity decreased during hypoxia. Taken together, this data indicates that hypoxic modulation of satellite cell-mediated angiogenesis involves a reduction in satellite cell HGF expression.

  17. Effect of vitamin D status improvement with 25-hydroxycholecalciferol on skeletal muscle growth characteristics and satellite cell activity in broiler chickens.

    PubMed

    Hutton, K C; Vaughn, M A; Litta, G; Turner, B J; Starkey, J D

    2014-08-01

    Skeletal muscle satellite cells (SC) play a critical role in the hypertrophic growth of postnatal muscle. Increases in breast meat yield have been consistently observed in broiler chickens fed 25-hydroxycholecalciferol (25OHD3), but it is unclear whether this effect is mediated by SC. Thus, our objective was to determine the effect of vitamin D status improvement by replacing the majority of dietary vitamin D3 (D3) with 25OHD3 on SC activity and muscle growth characteristics in the pectoralis major (PM) and the biceps femoris (BF) muscles. Day-old, male Ross 708 broiler chickens (n = 150) were fed 1 of 2 corn and soybean meal-based diets for 49 d. The control diet (CTL) contained 5,000 IU D3 per kg of diet and the experimental diet (25OHD3) contained 2,240 IU D3 per kg of diet + 2,760 IU 25OHD3 per kg of diet. Ten birds per treatment were harvested every 7 d. Two hours before harvest, birds were injected intraperitoneally with 5'-bromo-2'deoxyuridine (BrdU) to label mitotically active cells. Blood was collected from each bird at harvest to measure circulating concentrations of 25OHD3, a marker of vitamin D status. The PM and BF muscles were weighed and processed for cryohistological determination of skeletal muscle fiber cross-sectional area, enumeration of Myf-5+ and Pax7+ SC, and mitotically active (BrdU+) SC using immunofluorescence microscopy. Circulating 25OHD3 concentrations were greater in 25OHD3-fed birds on d 7, 14, 21, 28, 35, 42, and 49 when compared with CTL (P < 0.001). Growth performance and feed efficiency did not differ among dietary treatments (P > 0.10). Improved vitamin D status as a result of feeding 25OHD3 increased the number of mitotically active (Pax7+;BrdU+) SC (P = 0.01) and tended to increase the density of Pax7+ SC (P = 0.07) in the PM muscles of broilers on d 21 and 35, respectively. Broiler chickens fed 25OHD3 also tended to have greater Myf-5+ SC density (P = 0.09) on d 14, greater total nuclear density (P = 0.05) on d 28, and a

  18. High concentrations of HGF inhibit skeletal muscle satellite cell proliferation in vitro by inducing expression of myostatin: a possible mechanism for reestablishing satellite cell quiescence in vivo.

    PubMed

    Yamada, Michiko; Tatsumi, Ryuichi; Yamanouchi, Keitaro; Hosoyama, Tohru; Shiratsuchi, Sei-ichi; Sato, Akiko; Mizunoya, Wataru; Ikeuchi, Yoshihide; Furuse, Mitsuhiro; Allen, Ronald E

    2010-03-01

    Skeletal muscle regeneration and work-induced hypertrophy rely on molecular events responsible for activation and quiescence of resident myogenic stem cells, satellite cells. Recent studies demonstrated that hepatocyte growth factor (HGF) triggers activation and entry into the cell cycle in response to mechanical perturbation, and that subsequent expression of myostatin may signal a return to cell quiescence. However, mechanisms responsible for coordinating expression of myostatin after an appropriate time lag following activation and proliferation are not clear. Here we address the possible role of HGF in quiescence through its concentration-dependent negative-feedback mechanism following satellite cell activation and proliferation. When activated/proliferating satellite cell cultures were treated for 24 h beginning 48-h postplating with 10-500 ng/ml HGF, the percentage of bromodeoxyuridine-incorporating cells decreased down to a baseline level comparable to 24-h control cultures in a HGF dose-dependent manner. The high level HGF treatment did not impair the cell viability and differentiation levels, and cells could be reactivated by lowering HGF concentrations to 2.5 ng/ml, a concentration that has been shown to optimally stimulate activation of satellite cells in culture. Coaddition of antimyostatin neutralizing antibody could prevent deactivation and abolish upregulation of cyclin-dependent kinase (Cdk) inhibitor p21. Myostatin mRNA expression was upregulated with high concentrations of HGF, as demonstrated by RT-PCR, and enhanced myostatin protein expression and secretion were revealed by Western blots of the cell lysates and conditioned media. These results indicate that HGF could induce satellite cell quiescence by stimulating myostatin expression. The HGF concentration required (over 10-50 ng/ml), however, is much higher than that for activation, which is initiated by rapid release of HGF from its extracellular association. Considering that HGF is produced

  19. Myostatin signals through Pax7 to regulate satellite cell self-renewal

    SciTech Connect

    McFarlane, Craig; Hennebry, Alex; Thomas, Mark; Plummer, Erin; Ling, Nicholas; Sharma, Mridula; Kambadur, Ravi

    2008-01-15

    Myostatin, a Transforming Growth Factor-beta (TGF-{beta}) super-family member, has previously been shown to negatively regulate satellite cell activation and self-renewal. However, to date the mechanism behind Myostatin function in satellite cell biology is not known. Here we show that Myostatin signals via a Pax7-dependent mechanism to regulate satellite cell self-renewal. While excess Myostatin inhibited Pax7 expression via ERK1/2 signaling, an increase in Pax7 expression was observed following both genetic inactivation and functional antagonism of Myostatin. As a result, we show that either blocking or inactivating Myostatin enhances the partitioning of the fusion-incompetent self-renewed satellite cell lineage (high Pax7 expression, low MyoD expression) from the pool of actively proliferating myogenic precursor cells. Consistent with this result, over-expression of Pax7 in C2C12 myogenic cells resulted in increased self-renewal through a mechanism which slowed both myogenic proliferation and differentiation. Taken together, these results suggest that increased expression of Pax7 promotes satellite cell self-renewal, and furthermore Myostatin may control the process of satellite cell self-renewal through regulation of Pax7. Thus we speculate that, in addition to the intrinsic factors (such as Pax7), extrinsic factors both positive and negative in nature, will play a major role in determining the stemness of skeletal muscle satellite cells.

  20. Acute effects of hindlimb unweighting on satellite cells of growing skeletal muscle

    NASA Technical Reports Server (NTRS)

    Schultz, Edward; Darr, Kevin C.; Macius, Allison

    1994-01-01

    The proliferative behavior of satellite cells in growing rat soleus and extensor digitorum longus muscles was examined at short periods after initiation of hindlimb unweighting. Mitotic activity of satellite cells in both muscles decreased below weight-bearing control levels within 24 h of initiation of hindlimb unweighting. This satellite cell response was equal to or greater than 48 h before any atrophic morphological changes that take place in the muscles. Suppression of mitotic activity was most severe in the soleus muscle where continuous infusion of label demonstrated that virtually all mitotic activity was abolished between 3 and 5 days. The results of this study suggest that satellite cell mitotic activity is a sensitive indicator of primary atrophic changes occurring in growing myofibers and may be a predictor of future morphological changes.

  1. Satellite cells from dystrophic muscle retain regenerative capacity.

    PubMed

    Boldrin, Luisa; Zammit, Peter S; Morgan, Jennifer E

    2015-01-01

    Duchenne muscular dystrophy is an inherited disorder that is characterized by progressive skeletal muscle weakness and wasting, with a failure of muscle maintenance/repair mediated by satellite cells (muscle stem cells). The function of skeletal muscle stem cells resident in dystrophic muscle may be perturbed by being in an increasing pathogenic environment, coupled with constant demands for repairing muscle. To investigate the contribution of satellite cell exhaustion to this process, we tested the functionality of satellite cells isolated from the mdx mouse model of Duchenne muscular dystrophy. We found that satellite cells derived from young mdx mice contributed efficiently to muscle regeneration within our in vivo mouse model. To then test the effects of long-term residence in a dystrophic environment, satellite cells were isolated from aged mdx muscle. Surprisingly, they were as functional as those derived from young or aged wild type donors. Removing satellite cells from a dystrophic milieu reveals that their regenerative capacity remains both intact and similar to satellite cells derived from healthy muscle, indicating that the host environment is critical for controlling satellite cell function.

  2. Satellite glial cells in sensory ganglia: from form to function.

    PubMed

    Hanani, Menachem

    2005-06-01

    Current information indicates that glial cells participate in all the normal and pathological processes of the central nervous system. Although much less is known about satellite glial cells (SGCs) in sensory ganglia, it appears that these cells share many characteristics with their central counterparts. This review presents information that has been accumulated recently on the physiology and pharmacology of SGCs. It appears that SGCs carry receptors for numerous neuroactive agents (e.g., ATP, bradykinin) and can therefore receive signals from other cells and respond to changes in their environment. Activation of SGCs might in turn influence neighboring neurons. Thus SGCs are likely to participate in signal processing and transmission in sensory ganglia. Damage to the axons of sensory ganglia is known to contribute to neuropathic pain. Such damage also affects SGCs, and it can be proposed that these cells have a role in pathological changes in the ganglia.

  3. A Pitx2-MicroRNA Pathway Modulates Cell Proliferation in Myoblasts and Skeletal-Muscle Satellite Cells and Promotes Their Commitment to a Myogenic Cell Fate.

    PubMed

    Lozano-Velasco, Estefanía; Vallejo, Daniel; Esteban, Francisco J; Doherty, Chris; Hernández-Torres, Francisco; Franco, Diego; Aránega, Amelia Eva

    2015-09-01

    The acquisition of a proliferating-cell status from a quiescent state as well as the shift between proliferation and differentiation are key developmental steps in skeletal-muscle stem cells (satellite cells) to provide proper muscle regeneration. However, how satellite cell proliferation is regulated is not fully understood. Here, we report that the c-isoform of the transcription factor Pitx2 increases cell proliferation in myoblasts by downregulating microRNA 15b (miR-15b), miR-23b, miR-106b, and miR-503. This Pitx2c-microRNA (miRNA) pathway also regulates cell proliferation in early-activated satellite cells, enhancing Myf5(+) satellite cells and thereby promoting their commitment to a myogenic cell fate. This study reveals unknown functions of several miRNAs in myoblast and satellite cell behavior and thus may have future applications in regenerative medicine.

  4. Skeletal muscle satellite cells cultured in simulated microgravity

    NASA Technical Reports Server (NTRS)

    Molnar, Greg; Hartzell, Charles R.; Schroedl, Nancy A.; Gonda, Steve R.

    1993-01-01

    Satellite cells are postnatal myoblasts responsible for providing additional nuclei to growing or regenerating muscle cells. Satellite cells retain the capacity to proliferate and differentiate in vitro and therefore provide a useful model to study postnatal muscle development. Most culture systems used to study postnatal muscle development are limited by the two-dimensional (2-D) confines of the culture dish. Limiting proliferation and differentiation of satellite cells in 2-D could potentially limit cell-cell contacts important for developing the level of organization in skeletal muscle obtained in vivo. Culturing satellite cells on microcarrier beads suspended in the High-Aspect-Ratio-Vessel (HARV) designed by NASA provides a low shear, three-dimensional (3-D) environment to study muscle development. Primary cultures established from anterior tibialis muscles of growing rats (approximately 200 gm) were used for all studies and were composed of greater than 75 % satellite cells. Different inoculation densities did not affect the proliferative potential of satellite cells in the HARV. Plating efficiency, proliferation, and glucose utilization were compared between 2-D flat culture and 3-D HARV culture. Plating efficiency (cells attached - cells plated x 100) was similar between the two culture systems. Proliferation was reduced in HARV cultures and this reduction was apparent for both satellite cells and non-satellite cells. Furthermore, reduction in proliferation within the HARV could not be attributed to reduced substrate availability since glucose levels in media from HARV and 2-D cell culture were similar. Morphologically, microcarrier beads within the HARVS were joined together by cells into three-dimensional aggregates composed of greater than 10 beads/aggregate. Aggregation of beads did not occur in the absence of cells. Myotubes were often seen on individual beads or spanning the surface of two beads. In summary, proliferation and differentiation of

  5. Six family genes control the proliferation and differentiation of muscle satellite cells

    SciTech Connect

    Yajima, Hiroshi; Motohashi, Norio; Ono, Yusuke; Sato, Shigeru; Ikeda, Keiko; Masuda, Satoru; Yada, Erica; Kanesaki, Hironori; Miyagoe-Suzuki, Yuko; Takeda, Shin'ichi; Kawakami, Kiyoshi

    2010-10-15

    Muscle satellite cells are essential for muscle growth and regeneration and their morphology, behavior and gene expression have been extensively studied. However, the mechanisms involved in their proliferation and differentiation remain elusive. Six1 and Six4 proteins were expressed in the nuclei of myofibers of adult mice and the numbers of myoblasts positive for Six1 and Six4 increased during regeneration of skeletal muscles. Six1 and Six4 were expressed in quiescent, activated and differentiated muscle satellite cells isolated from adult skeletal muscle. Overexpression of Six4 and Six5 repressed the proliferation and differentiation of satellite cells. Conversely, knockdown of Six5 resulted in augmented proliferation, and that of Six4 inhibited differentiation. Muscle satellite cells isolated from Six4{sup +/-}Six5{sup -/-} mice proliferated to higher cell density though their differentiation was not altered. Meanwhile, overproduction of Six1 repressed proliferation and promoted differentiation of satellite cells. In addition, Six4 and Six5 repressed, while Six1 activated myogenin expression, suggesting that the differential regulation of myogenin expression is responsible for the differential effects of Six genes. The results indicated the involvement of Six genes in the behavior of satellite cells and identified Six genes as potential target for manipulation of proliferation and differentiation of muscle satellite cells for therapeutic applications.

  6. Intraganglionic interactions between satellite cells and adult sensory neurons.

    PubMed

    Christie, Kimberly; Koshy, Dilip; Cheng, Chu; Guo, GuiFang; Martinez, Jose A; Duraikannu, Arul; Zochodne, Douglas W

    2015-07-01

    Perineuronal satellite cells have an intimate anatomical relationship with sensory neurons that suggests close functional collaboration and mutual support. We examined several facets of this relationship in adult sensory dorsal root ganglia (DRG). Collaboration included the support of process outgrowth by clustering of satellite cells, induction of distal branching behavior by soma signaling, the capacity of satellite cells to respond to distal axon injury of its neighboring neurons, and evidence of direct neuron-satellite cell exchange. In vitro, closely adherent coharvested satellite cells routinely clustered around new outgrowing processes and groups of satellite cells attracted neurite processes. Similar clustering was encountered in the pseudounipolar processes of intact sensory neurons within intact DRG in vivo. While short term exposure of distal growth cones of unselected adult sensory neurons to transient gradients of a PTEN inhibitor had negligible impacts on their behavior, exposure of the soma induced early and substantial growth of their distant neurites and branches, an example of local soma signaling. In turn, satellite cells sensed when distal neuronal axons were injured by enlarging and proliferating. We also observed that satellite cells were capable of internalizing and expressing a neuron fluorochrome label, diamidino yellow, applied remotely to distal injured axons of the neuron and retrogradely transported to dorsal root ganglia sensory neurons. The findings illustrate a robust interaction between intranganglionic neurons and glial cells that involve two way signals, features that may be critical for both regenerative responses and ongoing maintenance.

  7. Karyopherin Alpha 1 Regulates Satellite Cell Proliferation and Survival by Modulating Nuclear Import.

    PubMed

    Choo, Hyo-Jung; Cutler, Alicia; Pavlath, Grace K

    2016-07-19

    Satellite cells are stem cells with an essential role in skeletal muscle repair. Precise regulation of gene expression is critical for proper satellite cell quiescence, proliferation, differentiation and self-renewal. Nuclear proteins required for gene expression are dependent on the nucleocytoplasmic transport machinery to access to nucleus, however little is known about regulation of nuclear transport in satellite cells. The best characterized nuclear import pathway is classical nuclear import which depends on a classical nuclear localization signal (cNLS) in a cargo protein and the heterodimeric import receptors, karyopherin alpha (KPNA) and beta (KPNB). Multiple KPNA1 paralogs exist and can differ in importing specific cNLS proteins required for cell differentiation and function. We show that transcripts for six Kpna paralogs underwent distinct changes in mouse satellite cells during muscle regeneration accompanied by changes in cNLS proteins in nuclei. Depletion of KPNA1, the most dramatically altered KPNA, caused satellite cells in uninjured muscle to prematurely activate, proliferate and undergo apoptosis leading to satellite cell exhaustion with age. Increased proliferation of satellite cells led to enhanced muscle regeneration at early stages of regeneration. In addition, we observed impaired nuclear localization of two key KPNA1 cargo proteins: p27, a cyclin-dependent kinase inhibitor associated with cell cycle control and lymphoid enhancer factor 1, a critical cotranscription factor for β-catenin. These results indicate that regulated nuclear import of proteins by KPNA1 is critical for satellite cell proliferation and survival and establish classical nuclear import as a novel regulatory mechanism for controlling satellite cell fate. Stem Cells 2016.

  8. PPARδ regulates satellite cell proliferation and skeletal muscle regeneration

    PubMed Central

    2011-01-01

    Peroxisome proliferator-activated receptors (PPARs) are a class of nuclear receptors that play important roles in development and energy metabolism. Whereas PPARδ has been shown to regulate mitochondrial biosynthesis and slow-muscle fiber types, its function in skeletal muscle progenitors (satellite cells) is unknown. Since constitutive mutation of Pparδ leads to embryonic lethality, we sought to address this question by conditional knockout (cKO) of Pparδ using Myf5-Cre/Pparδflox/flox alleles to ablate PPARδ in myogenic progenitor cells. Although Pparδ-cKO mice were born normally and initially displayed no difference in body weight, muscle size or muscle composition, they later developed metabolic syndrome, which manifested as increased body weight and reduced response to glucose challenge at age nine months. Pparδ-cKO mice had 40% fewer satellite cells than their wild-type littermates, and these satellite cells exhibited reduced growth kinetics and proliferation in vitro. Furthermore, regeneration of Pparδ-cKO muscles was impaired after cardiotoxin-induced injury. Gene expression analysis showed reduced expression of the Forkhead box class O transcription factor 1 (FoxO1) gene in Pparδ-cKO muscles under both quiescent and regenerating conditions, suggesting that PPARδ acts through FoxO1 in regulating muscle progenitor cells. These results support a function of PPARδ in regulating skeletal muscle metabolism and insulin sensitivity, and they establish a novel role of PPARδ in muscle progenitor cells and postnatal muscle regeneration. PMID:22040534

  9. Satellites

    SciTech Connect

    Burns, J.A.; Matthews, M.S.

    1986-01-01

    The present work is based on a conference: Natural Satellites, Colloquium 77 of the IAU, held at Cornell University from July 5 to 9, 1983. Attention is given to the background and origins of satellites, protosatellite swarms, the tectonics of icy satellites, the physical characteristics of satellite surfaces, and the interactions of planetary magnetospheres with icy satellite surfaces. Other topics include the surface composition of natural satellites, the cratering of planetary satellites, the moon, Io, and Europa. Consideration is also given to Ganymede and Callisto, the satellites of Saturn, small satellites, satellites of Uranus and Neptune, and the Pluto-Charon system.

  10. TRAF6 regulates satellite stem cell self-renewal and function during regenerative myogenesis.

    PubMed

    Hindi, Sajedah M; Kumar, Ashok

    2016-01-01

    Satellite cells are a stem cell population within adult muscle and are responsible for myofiber regeneration upon injury. Satellite cell dysfunction has been shown to underlie the loss of skeletal muscle mass in many acquired and genetic muscle disorders. The transcription factor paired box-protein-7 (PAX7) is indispensable for supplementing the reservoir of satellite cells and driving regeneration in normal and diseased muscle. TNF receptor-associated factor 6 (TRAF6) is an adaptor protein and an E3 ubiquitin ligase that mediates the activation of multiple cell signaling pathways in a context-dependent manner. Here, we demonstrated that TRAF6-mediated signaling is critical for homeostasis of satellite cells and their function during regenerative myogenesis. Selective deletion of Traf6 in satellite cells of adult mice led to profound muscle regeneration defects and dramatically reduced levels of PAX7 and late myogenesis markers. TRAF6 was required for the activation of MAPKs ERK1/2 and JNK1/2, which in turn activated the transcription factor c-JUN, which binds the Pax7 promoter and augments Pax7 expression. Moreover, TRAF6/c-JUN signaling repressed the levels of the microRNAs miR-1 and miR-206, which promote differentiation, to maintain PAX7 levels in satellite cells. We also determined that satellite cell-specific deletion of Traf6 exaggerates the dystrophic phenotype in the mdx (a mouse model of Duchenne muscular dystrophy) mouse by blunting the regeneration of injured myofibers. Collectively, our study reveals an essential role for TRAF6 in satellite stem cell function.

  11. Sulfs are regulators of growth factor signaling for satellite cell differentiation and muscle regeneration.

    PubMed

    Langsdorf, Aliete; Do, Anh-Tri; Kusche-Gullberg, Marion; Emerson, Charles P; Ai, Xingbin

    2007-11-15

    Heparan sulfate proteoglycans (HSPGs) are required during muscle regeneration for regulating extracellular signaling pathways. HSPGs interact with growth factors and receptors through heparan sulfate (HS) chains. However, the regulatory mechanisms that control HS sulfation to affect the growth factor-dependent proliferation and differentiation of satellite cells are yet unknown. Here we report the essential functions of extracellular HS 6-O-endosulfatases (Sulfs) during muscle regeneration. We show that quiescent and activated satellite cells differentially express mouse Sulf1 (MSulf1) and MSulf2. MSulfs are not required for the formation of skeletal muscles and satellite cells, but they have redundant, essential roles to promote muscle regeneration, as MSulf double mutant mice exhibit delayed myogenic differentiation and prolonged Pax7 expression after cardiotoxin-induced skeletal muscle injury, while single MSulf knockouts regenerate normally. HS structural analysis demonstrates that Sulfs are regulatory HS-modifying enzymes that control HS 6-O-desulfation of activated satellite cells. Mechanistically, we show that MSulfs repress FGF2 signaling in activated satellite cells, leading us to propose that MSulfs are growth factor signaling sensors to control the proliferation to differentiation switch of satellite cells to initiate differentiation during regeneration. Our results establish Sulfs as essential regulators of HS-dependent growth factor signaling in the adult muscle stem cell niche.

  12. Use of Advanced Solar Cells for Commercial Communication Satellites

    NASA Technical Reports Server (NTRS)

    Bailey, Sheila G.; Landis, Geoffrey A.

    1995-01-01

    The current generation of communications satellites are located primarily in geosynchronous Earth orbit (GEO). Over the next decade, however, a new generation of communications satellites will be built and launched, designed to provide a world-wide interconnection of portable telephones. For this mission, the satellites must be positioned in lower polar and near-polar orbits. To provide complete coverage, large numbers of satellites will be required. Because the required number of satellites decreases as the orbital altitude is increased, fewer satellites would be required if the orbit chosen were raised from low to intermediate orbit. However, in intermediate orbits, satellites encounter significant radiation due to trapped electrons and protons. Radiation tolerant solar cells may be necessary to make such satellites feasible. We analyze the amount of radiation encountered in low and intermediate polar orbits at altitudes of interest to next-generation communication satellites, calculate the expected degradation for silicon, GaAs, and InP solar cells, and show that the lifetimes can be significantly increased by use of advanced solar cells.

  13. Use of advanced solar cells for commercial communication satellites

    NASA Astrophysics Data System (ADS)

    Bailey, Sheila G.; Landis, Geoffrey A.

    1995-03-01

    The current generation of communications satellites are located primarily in geosynchronous Earth orbit (GEO). Over the next decade, however, a new generation of communications satellites will be built and launched, designed to provide a world-wide interconnection of portable telephones. For this mission, the satellites must be positioned in lower polar and near-polar orbits. To provide complete coverage, large numbers of satellites will be required. Because the required number of satellites decreases as the orbital altitude is increased, fewer satellites would be required if the orbit chosen were raised from low to intermediate orbit. However, in intermediate orbits, satellites encounter significant radiation due to trapped electrons and protons. Radiation tolerant solar cells may be necessary to make such satellites feasible. We analyze the amount of radiation encountered in low and intermediate polar orbits at altitudes of interest to next-generation communication satellites, calculate the expected degradation for silicon, GaAs, and InP solar cells, and show that the lifetimes can be significantly increased by use of advanced solar cells.

  14. Use of advanced solar cells for commerical communication satellites

    NASA Astrophysics Data System (ADS)

    Landis, Geoffrey A.; Bailey, Sheila G.

    1995-01-01

    The current generation of communications satellites are located primarily in geosynchronous Earth orbit (GEO). Over the next decade, however, a new generation of communications satellites will be built and launched, designed to provide a world-wide interconnection of portable telephones. For this mission, the satellites must be positioned in lower polar- and near-polar orbits. To provide complete coverage, large numbers of satellites will be required. Because of the required number of satellites decreases as the orbital altitude is increased, fewer satellites would be required if the orbit chosen were raised from Low to intermediate orbit. However, in intermediate orbits, satellites encounter significant radiation due to trapped electrons and protons. Radiation tolerant solar cells may be necessary to make such satellites feasible. We analyze the amount of radiation encountered in low and intermediate polar orbits at altitudes of interest to next-generation communication satellites, calculate the expected degradation for silicon, GaAs, and InP solar cells, and show that the lifetimes can be significantly increased by use of advanced solar cells.

  15. Pitx genes are redeployed in adult myogenesis where they can act to promote myogenic differentiation in muscle satellite cells.

    PubMed

    Knopp, Paul; Figeac, Nicolas; Fortier, Mathieu; Moyle, Louise; Zammit, Peter S

    2013-05-01

    Skeletal muscle retains a resident stem cell population called satellite cells. Although mitotically quiescent in mature muscle, satellite cells can be activated to produce myoblast progeny to generate myonuclei for skeletal muscle homoeostasis, hypertrophy and repair. Regulation of satellite cell function in adult requires redeployment of many of the regulatory networks fundamental to developmental myogenesis. Involved in such control of muscle stem cell fate in embryos are members of the Pitx gene family of bicoid-class homeodomain proteins. Here, we investigated the expression and function of all three Pitx genes in muscle satellite cells of adult mice. Endogenous Pitx1 was undetectable, whilst Pitx2a, Pitx2b and Pitx2c were at low levels in proliferating satellite cells, but increased during the early stages of myogenic differentiation. By contrast, proliferating satellite cells expressed robust amounts of Pitx3, with levels then decreasing as cells differentiated, although Pitx3 remained expressed in unfused myoblasts. To examine the role of Pitx genes in satellite cell function, retroviral-mediated expression of Pitx1, all Pitx2 isoforms or Pitx3, was used. Constitutive expression of any Pitx isoform suppressed satellite cell proliferation, with the cells undergoing enhanced myogenic differentiation. Conversely, myogenic differentiation into multinucleated myotubes was decreased when Pitx2 or Pitx3 levels were reduced using siRNA. Together, our results show that Pitx genes play a role in regulating satellite cell function during myogenesis in adult.

  16. Elevated satellite cell number in Duchenne muscular dystrophy.

    PubMed

    Kottlors, Michael; Kirschner, Janbernd

    2010-06-01

    The regenerative potential of muscle tissue relies mostly on satellite cells situated between the muscular basal membrane and the sarcolemma. The regeneration of muscle tissue comprises proliferation, the propagation of satellite cells, and their subsequent differentiation with the expression of multiple muscle-specific proteins. However, in Duchenne muscular dystrophy (DMD), regeneration cannot compensate for the loss of muscle tissue. To examine the regenerative potential in DMD, satellite cell nuclei number and markers of differentiation in DMD muscle from various disease states were compared with control muscle. Differentiation of satellite cells is characterized by the helix-loop-helix factor myogenin, which is never co-expressed with Pax7, whereas MyoD1 and Myf5 are co-expressed with Pax7, with Myf5 being present even in muscle of controls. The results indicate that satellite cell number is elevated in DMD in comparison with control muscle, even in advanced stages of dystrophy, suggesting that exhaustion of satellite cells is not the primary cause for failed regeneration. The expression of myogenin is correlated neither with fibrosis nor with age. We suggest variable factors influencing the differentiation of satellite cells in DMD.

  17. Satellite data-relay activities in Arizona

    USGS Publications Warehouse

    Boner, F.C.; Blee, J.W.; Shope, W.G.

    1985-01-01

    The U.S. Geological Survey (USGS) Arizona District collects data from automated streamflow stations for a wide variety of uses. Data from these stations are provided to Federal, State, and local agencies that have a responsibility to issue flood warnings; to generate forecasts of water availability; to monitor flow to insure compliance with treaties and other legal mandates; and to manage reservoirs for hydropower, flood abatement, and municipal and irrigation water supply. In the mid-1970's, the escalation of data collection costs and a need for more timely data led the Arizona District to examine alternatives for remote data acquisition. On the basis of successful data communications experiments with NASA 's Landsat satellite, an operational system for satellite-data relay was developed in 1976 using the National Oceanic and Atmospheric Administrations 's (NOAA) Geostationary Operational Environmental Satellite (GOES). A total of 62 data collection platforms (DCP's) was operated in 1983. Satellite telemetry operations are controlled at the remote data-collection stations by small battery-operated data collection platforms. The DCP 's periodically collect data from the sensors, store the data in computer memory, and at preset times transmit the data to the GOES satellite. The satellite retransmits the data to Earth where a ground-receive station transmits or transfers the data by land communications to the USGS computer in Reston, Virginia, for processing. The satellite relay transfers the data from sensor to computer in minutes; therefore, the data are available to users on a near real-time basis. (Author 's abstract)

  18. Effective fiber hypertrophy in satellite cell-depleted skeletal muscle.

    PubMed

    McCarthy, John J; Mula, Jyothi; Miyazaki, Mitsunori; Erfani, Rod; Garrison, Kelcye; Farooqui, Amreen B; Srikuea, Ratchakrit; Lawson, Benjamin A; Grimes, Barry; Keller, Charles; Van Zant, Gary; Campbell, Kenneth S; Esser, Karyn A; Dupont-Versteegden, Esther E; Peterson, Charlotte A

    2011-09-01

    An important unresolved question in skeletal muscle plasticity is whether satellite cells are necessary for muscle fiber hypertrophy. To address this issue, a novel mouse strain (Pax7-DTA) was created which enabled the conditional ablation of >90% of satellite cells in mature skeletal muscle following tamoxifen administration. To test the hypothesis that satellite cells are necessary for skeletal muscle hypertrophy, the plantaris muscle of adult Pax7-DTA mice was subjected to mechanical overload by surgical removal of the synergist muscle. Following two weeks of overload, satellite cell-depleted muscle showed the same increases in muscle mass (approximately twofold) and fiber cross-sectional area with hypertrophy as observed in the vehicle-treated group. The typical increase in myonuclei with hypertrophy was absent in satellite cell-depleted fibers, resulting in expansion of the myonuclear domain. Consistent with lack of nuclear addition to enlarged fibers, long-term BrdU labeling showed a significant reduction in the number of BrdU-positive myonuclei in satellite cell-depleted muscle compared with vehicle-treated muscle. Single fiber functional analyses showed no difference in specific force, Ca(2+) sensitivity, rate of cross-bridge cycling and cooperativity between hypertrophied fibers from vehicle and tamoxifen-treated groups. Although a small component of the hypertrophic response, both fiber hyperplasia and regeneration were significantly blunted following satellite cell depletion, indicating a distinct requirement for satellite cells during these processes. These results provide convincing evidence that skeletal muscle fibers are capable of mounting a robust hypertrophic response to mechanical overload that is not dependent on satellite cells.

  19. The satellite cell as a companion in skeletal muscle plasticity: currency, conveyance, clue, connector and colander.

    PubMed

    Anderson, Judy E

    2006-06-01

    Satellite cells are companions to voluntary muscle fibres, and are named for their intimate positional or ;satellite' relationship, as if revolving around fibres, like a satellite moon around the earth. Studies on the nature of at least some satellite cells, including their capabilities for self-renewal and for giving rise to multiple lineages in a stem cell-like function, are exploring the molecular basis of phenotypes described by markers of specialized function and gene expression in normal development, neuromuscular disease and aging. In adult skeletal muscle, the self-renewing capacity of satellite cells contributes to muscle growth, adaptation and regeneration. Muscle remodeling, such as demonstrated by changes in myofibre cross-sectional area and length, nerve and tendon junctions, and fibre-type distribution, occur in the absence of injury and provide broad functional and structural diversity among skeletal muscles. Those contributions to plasticity involve the satellite cell in at least five distinct roles, here described using metaphors for behaviour or the investigator's perspective. Satellite cells are the 'currency' of muscle; have a 'conveyance' role in adaptation by domains of cytoplasm along a myofibre; serve researchers, through a marker role, as 'clues' to various activities of muscle; are 'connectors' that physically, and through signalling and cell-fibre communications, bridge myofibres to the intra- and extra-muscular environment; and are equipped as metabolic and genetic filters or 'colanders' that can rectify or modulate particular signals. While all these roles are still under exploration, each contributes to the plasticity of skeletal muscle and thence to the overall biology and function of an organism. The use of metaphor for describing these roles helps to clarify and scrutinize the definitions that form the basis of our understanding of satellite cell biology: the metaphors provide the construct for various approaches to detect or test

  20. The muscle satellite cell at 50: the formative years

    PubMed Central

    2011-01-01

    In February 1961, Alexander Mauro described a cell 'wedged' between the plasma membrane of the muscle fibre and the surrounding basement membrane. He postulated that it could be a dormant myoblast, poised to repair muscle when needed. In the same month, Bernard Katz also reported a cell in a similar location on muscle spindles, suggesting that it was associated with development and growth of intrafusal muscle fibres. Both Mauro and Katz used the term 'satellite cell' in relation to their discoveries. Today, the muscle satellite cell is widely accepted as the resident stem cell of skeletal muscle, supplying myoblasts for growth, homeostasis and repair. Since 2011 marks both the 50th anniversary of the discovery of the satellite cell, and the launch of Skeletal Muscle, it seems an opportune moment to summarise the seminal events in the history of research into muscle regeneration. We start with the 19th-century pioneers who showed that muscle had a regenerative capacity, through to the descriptions from the mid-20th century of the underlying cellular mechanisms. The journey of the satellite cell from electron microscope curio, to its gradual acceptance as a bona fide myoblast precursor, is then charted: work that provided the foundations for our understanding of the role of the satellite cell. Finally, the rapid progress in the age of molecular biology is briefly discussed, and some ongoing debates on satellite cell function highlighted. PMID:21849021

  1. Electrical stimulation influences satellite cell proliferation and apoptosis in unloading-induced muscle atrophy in mice.

    PubMed

    Guo, Bao-Sheng; Cheung, Kwok-Kuen; Yeung, Simon S; Zhang, Bao-Ting; Yeung, Ella W

    2012-01-01

    Muscle atrophy caused by disuse is accompanied by adverse physiological and functional consequences. Satellite cells are the primary source of skeletal muscle regeneration. Satellite cell dysfunction, as a result of impaired proliferative potential and/or increased apoptosis, is thought to be one of the causes contributing to the decreased muscle regeneration capacity in atrophy. We have previously shown that electrical stimulation improved satellite cell dysfunction. Here we test whether electrical stimulation can also enhance satellite cell proliferative potential as well as suppress apoptotic cell death in disuse-induced muscle atrophy. Eight-week-old male BALB/c mice were subjected to a 14-day hindlimb unloading procedure. During that period, one limb (HU-ES) received electrical stimulation (frequency: 20 Hz; duration: 3 h, twice daily) while the contralateral limb served as control (HU). Immunohistochemistry and western blotting techniques were used to characterize specific proteins in cell proliferation and apoptosis. The HU-ES soleus muscles showed significant improvement in muscle mass, cross-sectional area, and peak tetanic force relative to the HU limb (p<0.05). The satellite cell proliferative activity as detected within the BrdU+/Pax7+ population was significantly higher (p<0.05). The apoptotic myonuclei (detected by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling) and the apoptotic satellite cells (detected by cleaved Poly [ADP-ribose] polymerase co-labeled with Pax7) were reduced (p<0.05) in the HU-ES limb. Furthermore the apoptosis-inducing factor and cleaved caspase-3 were down-regulated while the anti-apoptotic Bcl-2 protein was up-regulated (p<0.05), in the HU-ES limb. These findings suggest that the electrical stimulation paradigm provides an effective stimulus to rescue the loss of myonuclei and satellite cells in disuse muscle atrophy, thus maintaining a viable satellite cell pool for subsequent muscle regeneration

  2. Isolation, Culture, Functional Assays, and Immunofluorescence of Myofiber-Associated Satellite Cells.

    PubMed

    Vogler, Thomas O; Gadek, Katherine E; Cadwallader, Adam B; Elston, Tiffany L; Olwin, Bradley B

    2016-01-01

    Adult skeletal muscle stem cells, termed satellite cells, regenerate and repair the functional contractile cells in adult skeletal muscle called myofibers. Satellite cells reside in a niche between the basal lamina and sarcolemma of myofibers. Isolating single myofibers and their associated satellite cells provides a culture system that partially mimics the in vivo environment. We describe methods for isolating and culturing intact individual myofibers and their associated satellite cells from the mouse extensor digitorum longus muscle. Following dissection and isolation of individual myofibers we provide protocols for myofiber transplantation, satellite cell transfection, immune detection of satellite cell antigens, and assays to examine satellite cell self-renewal and proliferation.

  3. Human Satellite Cell Transplantation and Regeneration from Diverse Skeletal Muscles

    PubMed Central

    Xu, Xiaoti; Wilschut, Karlijn J.; Kouklis, Gayle; Tian, Hua; Hesse, Robert; Garland, Catharine; Sbitany, Hani; Hansen, Scott; Seth, Rahul; Knott, P. Daniel; Hoffman, William Y.; Pomerantz, Jason H.

    2015-01-01

    Summary Identification of human satellite cells that fulfill muscle stem cell criteria is an unmet need in regenerative medicine. This hurdle limits understanding how closely muscle stem cell properties are conserved among mice and humans and hampers translational efforts in muscle regeneration. Here, we report that PAX7 satellite cells exist at a consistent frequency of 2–4 cells/mm of fiber in muscles of the human trunk, limbs, and head. Xenotransplantation into mice of 50–70 fiber-associated, or 1,000–5,000 FACS-enriched CD56+/CD29+ human satellite cells led to stable engraftment and formation of human-derived myofibers. Human cells with characteristic PAX7, CD56, and CD29 expression patterns populated the satellite cell niche beneath the basal lamina on the periphery of regenerated fibers. After additional injury, transplanted satellite cells robustly regenerated to form hundreds of human-derived fibers. Together, these findings conclusively delineate a source of bona-fide endogenous human muscle stem cells that will aid development of clinical applications. PMID:26352798

  4. Human Satellite Cell Transplantation and Regeneration from Diverse Skeletal Muscles.

    PubMed

    Xu, Xiaoti; Wilschut, Karlijn J; Kouklis, Gayle; Tian, Hua; Hesse, Robert; Garland, Catharine; Sbitany, Hani; Hansen, Scott; Seth, Rahul; Knott, P Daniel; Hoffman, William Y; Pomerantz, Jason H

    2015-09-08

    Identification of human satellite cells that fulfill muscle stem cell criteria is an unmet need in regenerative medicine. This hurdle limits understanding how closely muscle stem cell properties are conserved among mice and humans and hampers translational efforts in muscle regeneration. Here, we report that PAX7 satellite cells exist at a consistent frequency of 2-4 cells/mm of fiber in muscles of the human trunk, limbs, and head. Xenotransplantation into mice of 50-70 fiber-associated, or 1,000-5,000 FACS-enriched CD56(+)/CD29(+) human satellite cells led to stable engraftment and formation of human-derived myofibers. Human cells with characteristic PAX7, CD56, and CD29 expression patterns populated the satellite cell niche beneath the basal lamina on the periphery of regenerated fibers. After additional injury, transplanted satellite cells robustly regenerated to form hundreds of human-derived fibers. Together, these findings conclusively delineate a source of bona-fide endogenous human muscle stem cells that will aid development of clinical applications.

  5. Satellite Cells Contribution to Exercise Mediated Muscle Hypertrophy and Repair

    PubMed Central

    Bazgir, Behzad; Fathi, Rouhollah; Rezazadeh Valojerdi, Mojtaba; Mozdziak, Paul; Asgari, Alireza

    2017-01-01

    Satellite cells (SCs) are the most abundant skeletal muscle stem cells. They are widely recognized for their contributions to maintenance of muscle mass, regeneration and hypertrophy during the human life span. These cells are good candidates for cell therapy due to their self-renewal capabilities and presence in an undifferentiated form. Presently, a significant gap exists between our knowledge of SCs behavior and their application as a means for human skeletal muscle tissue repair and regeneration. Both physiological and pathological stimuli potentially affect SCs activation, proliferation, and terminal differentiation the former category being the focus of this article. Activation of SCs occurs following exercise, post-training micro-injuries, and electrical stimulation. Exercise, as a potent and natural stimulus, is at the center of numerous studies on SC activation and relevant fields. According to research, different exercise modalities end with various effects. This review article attempts to picture the state of the art of the SCs life span and their engagement in muscle regeneration and hypertrophy in exercise. PMID:28042532

  6. The Hippo pathway member Yap plays a key role in influencing fate decisions in muscle satellite cells

    PubMed Central

    Judson, Robert N.; Tremblay, Annie M.; Knopp, Paul; White, Robert B.; Urcia, Roby; De Bari, Cosimo; Zammit, Peter S.; Camargo, Fernando D.; Wackerhage, Henning

    2012-01-01

    Summary Satellite cells are the resident stem cells of skeletal muscle. Mitotically quiescent in mature muscle, they can be activated to proliferate and generate myoblasts to supply further myonuclei to hypertrophying or regenerating muscle fibres, or self-renew to maintain the resident stem cell pool. Here, we identify the transcriptional co-factor Yap as a novel regulator of satellite cell fate decisions. Yap expression increases during satellite cell activation and Yap remains highly expressed until after the differentiation versus self-renewal decision is made. Constitutive expression of Yap maintains Pax7+ and MyoD+ satellite cells and satellite cell-derived myoblasts, promotes proliferation but prevents differentiation. In contrast, Yap knockdown reduces the proliferation of satellite cell-derived myoblasts by ≈40%. Consistent with the cellular phenotype, microarrays show that Yap increases expression of genes associated with Yap inhibition, the cell cycle, ribosome biogenesis and that it represses several genes associated with angiotensin signalling. We also identify known regulators of satellite cell function such as BMP4, CD34 and Myf6 (Mrf4) as genes whose expression is dependent on Yap activity. Finally, we confirm in myoblasts that Yap binds to Tead transcription factors and co-activates MCAT elements which are enriched in the proximal promoters of Yap-responsive genes. PMID:23038772

  7. Human Skeletal Muscle-derived CD133(+) Cells Form Functional Satellite Cells After Intramuscular Transplantation in Immunodeficient Host Mice.

    PubMed

    Meng, Jinhong; Chun, Soyon; Asfahani, Rowan; Lochmüller, Hanns; Muntoni, Francesco; Morgan, Jennifer

    2014-05-01

    Stem cell therapy is a promising strategy for treatment of muscular dystrophies. In addition to muscle fiber formation, reconstitution of functional stem cell pool by donor cells is vital for long-term treatment. We show here that some CD133(+) cells within human muscle are located underneath the basal lamina of muscle fibers, in the position of the muscle satellite cell. Cultured hCD133(+) cells are heterogeneous and multipotent, capable of forming myotubes and reserve satellite cells in vitro. They contribute to extensive muscle regeneration and satellite cell formation following intramuscular transplantation into irradiated and cryodamaged tibialis anterior muscles of immunodeficient Rag2-/γ chain-/C5-mice. Some donor-derived satellite cells expressed the myogenic regulatory factor MyoD, indicating that they were activated. In addition, when transplanted host muscles were reinjured, there was significantly more newly-regenerated muscle fibers of donor origin in treated than in control, nonreinjured muscles, indicating that hCD133(+) cells had given rise to functional muscle stem cells, which were able to activate in response to injury and contribute to a further round of muscle regeneration. Our findings provide new evidence for the location and characterization of hCD133(+) cells, and highlight that these cells are highly suitable for future clinical application.

  8. Human skeletal muscle-derived CD133(+) cells form functional satellite cells after intramuscular transplantation in immunodeficient host mice.

    PubMed

    Meng, Jinhong; Chun, Soyon; Asfahani, Rowan; Lochmüller, Hanns; Muntoni, Francesco; Morgan, Jennifer

    2014-05-01

    Stem cell therapy is a promising strategy for treatment of muscular dystrophies. In addition to muscle fiber formation, reconstitution of functional stem cell pool by donor cells is vital for long-term treatment. We show here that some CD133(+) cells within human muscle are located underneath the basal lamina of muscle fibers, in the position of the muscle satellite cell. Cultured hCD133(+) cells are heterogeneous and multipotent, capable of forming myotubes and reserve satellite cells in vitro. They contribute to extensive muscle regeneration and satellite cell formation following intramuscular transplantation into irradiated and cryodamaged tibialis anterior muscles of immunodeficient Rag2-/γ chain-/C5-mice. Some donor-derived satellite cells expressed the myogenic regulatory factor MyoD, indicating that they were activated. In addition, when transplanted host muscles were reinjured, there was significantly more newly-regenerated muscle fibers of donor origin in treated than in control, nonreinjured muscles, indicating that hCD133(+) cells had given rise to functional muscle stem cells, which were able to activate in response to injury and contribute to a further round of muscle regeneration. Our findings provide new evidence for the location and characterization of hCD133(+) cells, and highlight that these cells are highly suitable for future clinical application.

  9. [Molecular mechanism maintaining muscle satellite cells and the roles in sarcopenia.

    PubMed

    Takemoto, Yusei; Fukada, So-Ichiro

    2017-01-01

    Skeletal muscle has its stem cell named satellite cell. The absence of satellite cells does not allow muscle regeneration, it is unquestionable that satellite cell is indispensable for muscle regeneration processes. A certain number of satellite cells appear to be necessary for the successful muscle regeneration, meaning the maintenance of the satellite cells is essential for the functional homeostasis of skeletal muscle. Recent studies have revealed the molecular mechanism underlying satellite cell maintenance in a steady state. A loss of those molecules responsible for the maintenance often results in decreased satellite cell pool and reduced regeneration ability. On the other hand, the contribution of satellite cells to muscle hypertrophy or aged-related atrophy(sarcopenia)is controversial. In this review, we will introduce the molecules that regulate satellite cells homeostasis in the dormant state and then further discuss the recent results on the roles of satellite cell in sarcopenia.

  10. About mechanisms of tetonic activity of the satellites

    NASA Astrophysics Data System (ADS)

    Barkin, Yu. V.

    2003-04-01

    ABOUT MECHANISMS OF TECTONIC ACTIVITY OF THE SATELLITES Yu.V. Barkin Sternberg Astronomical Institute, Moscow, Russia, barkin@sai.msu.ru Due to attraction of the central planet and others external bodies satellite is subjected by tidal and non-tidal deformations. Elastic energy is changed in dependence from mutual position and motion of celestial bodies and as result the tensional state of satellite and its tectonic (endogenous) activity also is changed. Satellites of the planets have the definite shell’s structure and due to own rotation these shells are characterized by different oblatenesses. Gravitational interaction of the satellite and its mother planet generates big additional mechanical forces (and moments) between the neighboring non-spherical shells of the satellite (mantle, core and crust). These forces and moments are cyclic functions of time, which are changed in the different time-scales. They generate corresponding cyclic perturbations of the tensional state of the shells, their deformations, small relative transnational displacements and slow rotation of the shells and others. In geological period of time it leads to a fundamental tectonic reconstruction of the body. Definite contribution to discussed phenomena are caused by classical tidal mechanism. of planet-satellite interaction. But in this report we discuss in first the new mechanisms of endogenous activity of celestial bodies. They are connected with differential gravitational attraction of non-spherical satellite shells by the external celestial bodies which leads: 1) to small relative rotation (nutations) of the shells; 2) to small relative translational motions of the shells (displacements of their center of mass); 3) to relative displacements and rotations of the shells due to eccentricity of their center of mass positions; 4) to viscous elastic deformations of the shells and oth. (Barkin, 2001). For higher evaluations of the power of satellite endogenous activities were obtained

  11. Conditional Cripto overexpression in satellite cells promotes myogenic commitment and enhances early regeneration

    PubMed Central

    Prezioso, Carolina; Iaconis, Salvatore; Andolfi, Gennaro; Zentilin, Lorena; Iavarone, Francescopaolo; Guardiola, Ombretta; Minchiotti, Gabriella

    2015-01-01

    Skeletal muscle regeneration mainly depends on satellite cells, a population of resident muscle stem cells. Despite extensive studies, knowledge of the molecular mechanisms underlying the early events associated with satellite cell activation and myogenic commitment in muscle regeneration remains still incomplete. Cripto is a novel regulator of postnatal skeletal muscle regeneration and a promising target for future therapy. Indeed, Cripto is expressed both in myogenic and inflammatory cells in skeletal muscle after acute injury and it is required in the satellite cell compartment to achieve effective muscle regeneration. A critical requirement to further explore the in vivo cellular contribution of Cripto in regulating skeletal muscle regeneration is the possibility to overexpress Cripto in its endogenous configuration and in a cell and time-specific manner. Here we report the generation and the functional characterization of a novel mouse model for conditional expression of Cripto, i.e., the Tg:DsRedloxP/loxPCripto-eGFP mice. Moreover, by using a satellite cell specific Cre-driver line we investigated the biological effect of Cripto overexpression in vivo, and provided evidence that overexpression of Cripto in the adult satellite cell compartment promotes myogenic commitment and differentiation, and enhances early regeneration in a mouse model of acute injury. PMID:26052513

  12. Conditional Cripto overexpression in satellite cells promotes myogenic commitment and enhances early regeneration.

    PubMed

    Prezioso, Carolina; Iaconis, Salvatore; Andolfi, Gennaro; Zentilin, Lorena; Iavarone, Francescopaolo; Guardiola, Ombretta; Minchiotti, Gabriella

    2015-01-01

    Skeletal muscle regeneration mainly depends on satellite cells, a population of resident muscle stem cells. Despite extensive studies, knowledge of the molecular mechanisms underlying the early events associated with satellite cell activation and myogenic commitment in muscle regeneration remains still incomplete. Cripto is a novel regulator of postnatal skeletal muscle regeneration and a promising target for future therapy. Indeed, Cripto is expressed both in myogenic and inflammatory cells in skeletal muscle after acute injury and it is required in the satellite cell compartment to achieve effective muscle regeneration. A critical requirement to further explore the in vivo cellular contribution of Cripto in regulating skeletal muscle regeneration is the possibility to overexpress Cripto in its endogenous configuration and in a cell and time-specific manner. Here we report the generation and the functional characterization of a novel mouse model for conditional expression of Cripto, i.e., the Tg:DsRed (loxP/loxP) Cripto-eGFP mice. Moreover, by using a satellite cell specific Cre-driver line we investigated the biological effect of Cripto overexpression in vivo, and provided evidence that overexpression of Cripto in the adult satellite cell compartment promotes myogenic commitment and differentiation, and enhances early regeneration in a mouse model of acute injury.

  13. Gliopathic pain: when satellite glial cells go bad.

    PubMed

    Ohara, Peter T; Vit, Jean-Philippe; Bhargava, Aditi; Romero, Marcela; Sundberg, Christopher; Charles, Andrew C; Jasmin, Luc

    2009-10-01

    Neurons in sensory ganglia are surrounded by satellite glial cells (SGCs) that perform similar functions to the glia found in the CNS. When primary sensory neurons are injured, the surrounding SGCs undergo characteristic changes. There is good evidence that the SGCs are not just bystanders to the injury but play an active role in the initiation and maintenance of neuronal changes that underlie neuropathic pain. In this article the authors review the literature on the relationship between SGCs and nociception and present evidence that changes in SGC potassium ion buffering capacity and glutamate recycling can lead to neuropathic pain-like behavior in animal models. The role that SGCs play in the immune responses to injury is also considered. We propose the term gliopathic pain to describe those conditions in which central or peripheral glia are thought to be the principal generators of principal pain generators.

  14. Restricted maternal nutrition alters myogenic regulatory factor expression in satellite cells of ovine offspring.

    PubMed

    Raja, J S; Hoffman, M L; Govoni, K E; Zinn, S A; Reed, S A

    2016-07-01

    Poor maternal nutrition inhibits muscle development and postnatal muscle growth. Satellite cells are myogenic precursor cells that contribute to postnatal muscle growth, and their activity can be evaluated by the expression of several transcription factors. Paired-box (Pax)7 is expressed in quiescent and active satellite cells. MyoD is expressed in activated and proliferating satellite cells and myogenin is expressed in terminally differentiating cells. Disruption in the expression pattern or timing of expression of myogenic regulatory factors negatively affects muscle development and growth. We hypothesized that poor maternal nutrition during gestation would alter the in vitro temporal expression of MyoD and myogenin in satellite cells from offspring at birth and 3 months of age. Ewes were fed 100% or 60% of NRC requirements from day 31±1.3 of gestation. Lambs from control-fed (CON) or restricted-fed (RES) ewes were euthanized within 24 h of birth (birth; n=5) or were fed a control diet until 3 months of age (n=5). Satellite cells isolated from the semitendinosus muscle were used for gene expression analysis or cultured for 24, 48 or 72 h and immunostained for Pax7, MyoD or myogenin. Fusion index was calculated from a subset of cells allowed to differentiate. Compared with CON, temporal expression of MyoD and myogenin was altered in cultured satellite cells isolated from RES lambs at birth. The percent of cells expressing MyoD was greater in RES than CON (P=0.03) after 24 h in culture. After 48 h of culture, there was a greater percent of cells expressing myogenin in RES compared with CON (P0.05). In satellite cells from RES lambs at 3 months of age, the percent of cells expressing MyoD and myogenin were greater than CON after 72 h in culture (P<0.05). Fusion index was reduced in RES lambs at 3 months of age compared with CON (P<0.001). Restricted nutrition during gestation alters the temporal expression of myogenic regulatory factors in satellite cells of the

  15. Solar power satellites - Heat engine or solar cells

    NASA Technical Reports Server (NTRS)

    Oman, H.; Gregory, D. L.

    1978-01-01

    A solar power satellite is the energy-converting element of a system that can deliver some 10 GW of power to utilities on the earth's surface. We evaluated heat engines and solar cells for converting sunshine to electric power at the satellite. A potassium Rankine cycle was the best of the heat engines, and 50 microns thick single-crystal silicon cells were the best of the photovoltaic converters. Neither solar cells nor heat engines had a clear advantage when all factors were considered. The potassium-turbine power plant, however, was more difficult to assemble and required a more expensive orbital assembly base. We therefore based our cost analyses on solar-cell energy conversion, concluding that satellite-generated power could be delivered to utilities for around 4 to 5 cents a kWh.

  16. FACS-based Satellite Cell Isolation From Mouse Hind Limb Muscles.

    PubMed

    Gromova, Anastasia; Tierney, Matthew T; Sacco, Alessandra

    2015-08-20

    Fluorescence Activated Cell Sorting (FACS) is a sensitive and accurate method for purifying satellite cells, or muscle stem cells, from adult mouse skeletal muscle (Liu et al., 2013; Sacco et al., 2008; Tierney et al., 2014). Mechanical and enzymatic digestion of hind limb muscles releases mononuclear muscle cells into suspension. This protocol employs fractionation strategies to deplete cells expressing the cell surface markers CD45, CD31, CD11b and Ly-6A/E-Sca1, both by magnetic separation and FACS-based exclusion, and positively select for cells expressing a7-integrin and CD34. This enables the researcher to successfully enrich satellite cells that uniformly express the paired-box transcription factor Pax7 and are capable of long-term self-renewal, skeletal muscle repair and muscle stem cell pool repopulation.

  17. Function of Membrane-Associated Proteoglycans in the Regulation of Satellite Cell Growth.

    PubMed

    Song, Yan

    2016-01-01

    Muscle growth can be divided into embryonic and postnatal periods. During the embryonic period, mesenchymal stem cells proliferate and differentiate to form muscle fibers. Postnatal muscle growth (hypertrophy) is characterized by the enlargement of existing muscle fiber size. Satellite cells (also known as adult myoblasts) are responsible for hypertrophy. The activity of satellite cells can be regulated by their extracellular matrix (ECM). The ECM is composed of collagens, proteoglycans, non-collagenous glycoproteins, cytokines and growth factors. Proteoglycans contain a central core protein with covalently attached glycosaminoglycans (GAGs: chondroitin sulfate, keratan sulfate, dermatan sulfate, and heparan sulfate) and N- or O-linked glycosylation chains. Membrane-associated proteoglycans attach to the cell membrane either through a glycosylphosphatidylinositol anchor or transmembrane domain. The GAGs can bind proteins including cytokines and growth factors. Both cytokines and growth factors play important roles in regulating satellite cell growth and development. Cytokines are generally associated with immune cells. However, cytokines can also affect muscle cell development. For instance, interleukin-6, tumor necrosis factor-α, and leukemia inhibitory factor have been reported to affect the proliferation and differentiation of satellite cells and myoblasts. Growth factors are potent stimulators or inhibitors of satellite cell proliferation and differentiation. The proper function of some cytokines and growth factors requires an interaction with the cell membrane-associated proteoglycans to enhance the affinity to bind to their primary receptors to initiate downstream signal transduction. This chapter is focused on the interaction of membrane-associated proteoglycans with cytokines and growth factors, and their role in satellite cell growth and development.

  18. Low-energy laser irradiation affects satellite cell proliferation and differentiation in vitro.

    PubMed

    Ben-Dov, N; Shefer, G; Irintchev, A; Wernig, A; Oron, U; Halevy, O; Irinitchev, A

    1999-01-11

    Low-energy laser (He-Ne) irradiation was found to promote skeletal muscle regeneration in vivo. In this study, its effect on the proliferation and differentiation of satellite cells in vitro was evaluated. Primary rat satellite cells were irradiated for various time periods immediately after preparation, and thymidine incorporation was determined after 2 days in culture. Laser irradiation affected thymidine incorporation in a bell-shaped manner, with a peak at 3 s of irradiation. Three seconds of irradiation caused an induction of cell-cycle regulatory proteins: cyclin D1, cyclin E and cyclin A in an established line of mouse satellite cells, pmi28, and proliferating cell nuclear antigen (PCNA) in primary rat satellite cells. The induction of cyclins by laser irradiation was compatible with their induction by serum refeeding of the cells. Laser irradiation effect on cell proliferation was dependent on the rat's age. At 3 weeks of age, thymidine incorporation in the irradiated cells was more than twofold higher than that in the controls, while at 6 weeks of age this difference had almost disappeared. Myosin heavy chain (MHC) protein levels were twofold lower in the irradiated than in the control cells, whereas the proliferation of the irradiated cells was twofold higher. Fusion percentage was lower in the irradiated compared to non-irradiated cells. In light of these data, the promoting effect of laser irradiation on skeletal muscle regeneration in vivo may be due to its effect on the activation of early cell-cycle regulatory genes in satellite cells, leading to increased proliferation and to a delay in cell differentiation.

  19. New insights into the epigenetic control of satellite cells

    PubMed Central

    Moresi, Viviana; Marroncelli, Nicoletta; Adamo, Sergio

    2015-01-01

    Epigenetics finely tunes gene expression at a functional level without modifying the DNA sequence, thereby contributing to the complexity of genomic regulation. Satellite cells (SCs) are adult muscle stem cells that are important for skeletal post-natal muscle growth, homeostasis and repair. The understanding of the epigenome of SCs at different stages and of the multiple layers of the post-transcriptional regulation of gene expression is constantly expanding. Dynamic interactions between different epigenetic mechanisms regulate the appropriate timing of muscle-specific gene expression and influence the lineage fate of SCs. In this review, we report and discuss the recent literature about the epigenetic control of SCs during the myogenic process from activation to proliferation and from their commitment to a muscle cell fate to their differentiation and fusion to myotubes. We describe how the coordinated activities of the histone methyltransferase families Polycomb group (PcG), which represses the expression of developmentally regulated genes, and Trithorax group, which antagonizes the repressive activity of the PcG, regulate myogenesis by restricting gene expression in a time-dependent manner during each step of the process. We discuss how histone acetylation and deacetylation occurs in specific loci throughout SC differentiation to enable the time-dependent transcription of specific genes. Moreover, we describe the multiple roles of microRNA, an additional epigenetic mechanism, in regulating gene expression in SCs, by repressing or enhancing gene transcription or translation during each step of myogenesis. The importance of these epigenetic pathways in modulating SC activation and differentiation renders them as promising targets for disease interventions. Understanding the most recent findings regarding the epigenetic mechanisms that regulate SC behavior is useful from the perspective of pharmacological manipulation for improving muscle regeneration and for

  20. Satellite cell proliferation is reduced in muscles of obese Zucker rats but restored with loading.

    PubMed

    Peterson, Jonathan M; Bryner, Randall W; Alway, Stephen E

    2008-08-01

    The obese Zucker rat (OZR) is a model of metabolic syndrome, which has lower skeletal muscle size than the lean Zucker rat (LZR). Because satellite cells are essential for postnatal muscle growth, this study was designed to determine whether reduced satellite cell proliferation contributes to reduced skeletal mass in OZR vs. LZR. Satellite cell proliferation was determined by a constant-release 5-bromo-2-deoxyuridine (BrdU) pellet that was placed subcutaneously in each animal. Satellite cell proliferation, as determined by BrdU incorporation, was significantly attenuated in control soleus and plantaris muscles of the OZR compared with that shown in the LZR. To determine whether this attenuation of satellite cell activity could be rescued in OZR muscles, soleus and gastrocnemius muscles were denervated, placing a compensatory load on the plantaris muscle. In the LZR and the OZR after 21 days of loading, increases of approximately 25% and approximately 30%, respectively, were shown in plantaris muscle wet weight compared with that shown in the contralateral control muscle. The number of BrdU-positive nuclei increased similarly in loaded plantaris muscles from LZR and OZR. Myogenin, MyoD, and Akt protein expressions were lower in control muscles of OZR than in those of the LZR, but they were all elevated to similar levels in the loaded plantaris muscles of OZR and LZR. These data indicate that metabolic syndrome may reduce satellite cell proliferation, and this may be a factor that contributes to the reduced mass in control muscles of OZR; however, satellite cell proliferation can be restored with compensatory loading in OZR.

  1. Extracellular matrix proteoglycan decorin-mediated myogenic satellite cell responsiveness to transforming growth factor-beta1 during cell proliferation and differentiation Decorin and transforming growth factor-beta1 in satellite cells.

    PubMed

    Li, Xuehui; McFarland, Douglas C; Velleman, Sandra G

    2008-10-01

    Transforming growth factor-beta1 (TGF-beta1) is a potent inhibitor of muscle cell proliferation and differentiation. Decorin, a small proteoglycan in the extracellular matrix, binds to TGF-beta1 and modulates the activity of TGF-beta1 during muscle cell growth and development. However, its interaction with TGF-beta1 and involvement in myogenesis is not well characterized. In the present study, chicken myogenic satellite cells, myogenic precursors for muscle growth and repair, were isolated from the pectoralis major muscle and used to investigate the biological function of TGF-beta1 and decorin during myogenesis. The over-expression of decorin in satellite cells significantly increased cell proliferation, compared to the control cells. Consistent with this result, reducing decorin expression decreased cell proliferation, which suggests a decorin-mediated mechanism is involved in the regulation of myogenic satellite cell proliferation. Satellite cells over-expressing decorin were less sensitive to TGF-beta1 during proliferation, which indicates that decorin may sequester TGF-beta1 leading to increased proliferation. During satellite cell differentiation, the over-expression of decorin induced differentiation by increasing the muscle specific creatine kinase concentration. However, the addition of TGF-beta1 diminished decorin-mediated cell responsiveness to TGF-beta1 during differentiation. Taken together, these results suggest that decorin induces myogenic satellite cell proliferation and differentiation by regulating cellular responsiveness to TGF-beta1. An alternative TGF-beta1-independent pathway may be involved in the regulation of satellite cells by decorin.

  2. Neuronal somatic ATP release triggers neuron-satellite glial cell communication in dorsal root ganglia.

    PubMed

    Zhang, X; Chen, Y; Wang, C; Huang, L-Y M

    2007-06-05

    It has been generally assumed that the cell body (soma) of a neuron, which contains the nucleus, is mainly responsible for synthesis of macromolecules and has a limited role in cell-to-cell communication. Using sniffer patch recordings, we show here that electrical stimulation of dorsal root ganglion (DRG) neurons elicits robust vesicular ATP release from their somata. The rate of release events increases with the frequency of nerve stimulation; external Ca(2+) entry is required for the release. FM1-43 photoconversion analysis further reveals that small clear vesicles participate in exocytosis. In addition, the released ATP activates P2X7 receptors in satellite cells that enwrap each DRG neuron and triggers the communication between neuronal somata and glial cells. Blocking L-type Ca(2+) channels completely eliminates the neuron-glia communication. We further show that activation of P2X7 receptors can lead to the release of tumor necrosis factor-alpha (TNFalpha) from satellite cells. TNFalpha in turn potentiates the P2X3 receptor-mediated responses and increases the excitability of DRG neurons. This study provides strong evidence that somata of DRG neurons actively release transmitters and play a crucial role in bidirectional communication between neurons and surrounding satellite glial cells. These results also suggest that, contrary to the conventional view, neuronal somata have a significant role in cell-cell signaling.

  3. Colonization of the satellite cell niche by skeletal muscle progenitor cells depends on Notch signals.

    PubMed

    Bröhl, Dominique; Vasyutina, Elena; Czajkowski, Maciej T; Griger, Joscha; Rassek, Claudia; Rahn, Hans-Peter; Purfürst, Bettina; Wende, Hagen; Birchmeier, Carmen

    2012-09-11

    Skeletal muscle growth and regeneration rely on myogenic progenitor and satellite cells, the stem cells of postnatal muscle. Elimination of Notch signals during mouse development results in premature differentiation of myogenic progenitors and formation of very small muscle groups. Here we show that this drastic effect is rescued by mutation of the muscle differentiation factor MyoD. However, rescued myogenic progenitors do not assume a satellite cell position and contribute poorly to myofiber growth. The disrupted homing is due to a deficit in basal lamina assembly around emerging satellite cells and to their impaired adhesion to myofibers. On a molecular level, emerging satellite cells deregulate the expression of basal lamina components and adhesion molecules like integrin α7, collagen XVIIIα1, Megf10, and Mcam. We conclude that Notch signals control homing of satellite cells, stimulating them to contribute to their own microenvironment and to adhere to myofibers.

  4. Isolation and Culture of Individual Myofibers and their Satellite Cells from Adult Skeletal Muscle

    PubMed Central

    Pasut, Alessandra; Jones, Andrew E.; Rudnicki, Michael A.

    2013-01-01

    Muscle regeneration in the adult is performed by resident stem cells called satellite cells. Satellite cells are defined by their position between the basal lamina and the sarcolemma of each myofiber. Current knowledge of their behavior heavily relies on the use of the single myofiber isolation protocol. In 1985, Bischoff described a protocol to isolate single live fibers from the Flexor Digitorum Brevis (FDB) of adult rats with the goal to create an in vitro system in which the physical association between the myofiber and its stem cells is preserved 1. In 1995, Rosenblattmodified the Bischoff protocol such that myofibers are singly picked and handled separately after collagenase digestion instead of being isolated by gravity sedimentation 2, 3. The Rosenblatt or Bischoff protocol has since been adapted to different muscles, age or conditions 3-6. The single myofiber isolation technique is an indispensable tool due its unique advantages. First, in the single myofiber protocol, satellite cells are maintained beneath the basal lamina. This is a unique feature of the protocol as other techniques such as Fluorescence Activated Cell Sorting require chemical and mechanical tissue dissociation 7. Although the myofiber culture system cannot substitute for in vivo studies, it does offer an excellent platform to address relevant biological properties of muscle stem cells. Single myofibers can be cultured in standard plating conditions or in floating conditions. Satellite cells on floating myofibers are subjected to virtually no other influence than the myofiber environment. Substrate stiffness and coating have been shown to influence satellite cells' ability to regenerate muscles 8, 9 so being able to control each of these factors independently allows discrimination between niche-dependent and -independent responses. Different concentrations of serum have also been shown to have an effect on the transition from quiescence to activation. To preserve the quiescence state of

  5. Infrared power cells for satellite power conversion

    NASA Technical Reports Server (NTRS)

    Summers, Christopher J.

    1991-01-01

    An analytical investigation is performed to assess the feasibility of long-wavelength power converters for the direct conversion of IR radiation onto electrical power. Because theses devices need to operate between 5 and 30 um the only material system possible for this application is the HgCdTe system which is currently being developed for IR detectors. Thus solar cell and IR detector theories and technologies are combined. The following subject areas are covered: electronic and optical properties of HgCdTe alloys; optimum device geometry; junction theory; model calculation for homojunction power cell efficiency; and calculation for HgCdTe power cell and power beaming.

  6. Active vision in satellite scene analysis

    NASA Technical Reports Server (NTRS)

    Naillon, Martine

    1994-01-01

    In earth observation or planetary exploration it is necessary to have more and, more autonomous systems, able to adapt to unpredictable situations. This imposes the use, in artificial systems, of new concepts in cognition, based on the fact that perception should not be separated from recognition and decision making levels. This means that low level signal processing (perception level) should interact with symbolic and high level processing (decision level). This paper is going to describe the new concept of active vision, implemented in Distributed Artificial Intelligence by Dassault Aviation following a 'structuralist' principle. An application to spatial image interpretation is given, oriented toward flexible robotics.

  7. Life cycle testing of sodium/sulfur satellite battery cells

    NASA Astrophysics Data System (ADS)

    Flake, Richard A.

    Test results on sodium sulfur cells developed presently by the Air Force for NaS rechargeable batteries for baseload power applications are summarized. Cycle life data are presented on fourteen cells, some of which have accumulated more than 1900 days on test and/or more than 6000 cycles. Results demonstrated cycle life times to be sufficient for use on satellites in high-altitude orbits.

  8. Role of satellite glial cells in gastrointestinal pain.

    PubMed

    Hanani, Menachem

    2015-01-01

    Gastrointestinal (GI) pain is a common clinical problem, for which effective therapy is quite limited. Sensations from the GI tract, including pain, are mediated largely by neurons in the dorsal root ganglia (DRG), and to a smaller extent by vagal afferents emerging from neurons in the nodose/jugular ganglia. Neurons in rodent DRG become hyperexcitable in models of GI pain (e.g., gastric or colonic inflammation), and can serve as a source for chronic pain. Glial cells are another element in the pain signaling pathways, and there is evidence that spinal glial cells (microglia and astrocytes) undergo activation (gliosis) in various pain models and contribute to pain. Recently it was found that satellite glial cells (SGCs), the main type of glial cells in sensory ganglia, might also contribute to chronic pain in rodent models. Most of that work focused on somatic pain, but in several studies GI pain was also investigated, and these are discussed in the present review. We have shown that colonic inflammation induced by dinitrobenzene sulfonic acid (DNBS) in mice leads to the activation of SGCs in DRG and increases gap junction-mediated coupling among these cells. This coupling appears to contribute to the hyperexcitability of DRG neurons that innervate the colon. Blocking gap junctions (GJ) in vitro reduced neuronal hyperexcitability induced by inflammation, suggesting that glial GJ participate in SGC-neuron interactions. Moreover, blocking GJ by carbenoxolone and other agents reduces pain behavior. Similar changes in SGCs were also found in the mouse nodose ganglia (NG), which provide sensory innervation to most of the GI tract. Following systemic inflammation, SGCs in these ganglia were activated, and displayed augmented coupling and greater sensitivity to the pain mediator ATP. The contribution of these changes to visceral pain remains to be determined. These results indicate that although visceral pain is unique, it shares basic mechanisms with somatic pain

  9. Role of satellite glial cells in gastrointestinal pain

    PubMed Central

    Hanani, Menachem

    2015-01-01

    Gastrointestinal (GI) pain is a common clinical problem, for which effective therapy is quite limited. Sensations from the GI tract, including pain, are mediated largely by neurons in the dorsal root ganglia (DRG), and to a smaller extent by vagal afferents emerging from neurons in the nodose/jugular ganglia. Neurons in rodent DRG become hyperexcitable in models of GI pain (e.g., gastric or colonic inflammation), and can serve as a source for chronic pain. Glial cells are another element in the pain signaling pathways, and there is evidence that spinal glial cells (microglia and astrocytes) undergo activation (gliosis) in various pain models and contribute to pain. Recently it was found that satellite glial cells (SGCs), the main type of glial cells in sensory ganglia, might also contribute to chronic pain in rodent models. Most of that work focused on somatic pain, but in several studies GI pain was also investigated, and these are discussed in the present review. We have shown that colonic inflammation induced by dinitrobenzene sulfonic acid (DNBS) in mice leads to the activation of SGCs in DRG and increases gap junction-mediated coupling among these cells. This coupling appears to contribute to the hyperexcitability of DRG neurons that innervate the colon. Blocking gap junctions (GJ) in vitro reduced neuronal hyperexcitability induced by inflammation, suggesting that glial GJ participate in SGC-neuron interactions. Moreover, blocking GJ by carbenoxolone and other agents reduces pain behavior. Similar changes in SGCs were also found in the mouse nodose ganglia (NG), which provide sensory innervation to most of the GI tract. Following systemic inflammation, SGCs in these ganglia were activated, and displayed augmented coupling and greater sensitivity to the pain mediator ATP. The contribution of these changes to visceral pain remains to be determined. These results indicate that although visceral pain is unique, it shares basic mechanisms with somatic pain

  10. Somitic origin of limb muscle satellite and side population cells

    PubMed Central

    Schienda, Jaclyn; Engleka, Kurt A.; Jun, Susan; Hansen, Mark S.; Epstein, Jonathan A.; Tabin, Clifford J.; Kunkel, Louis M.; Kardon, Gabrielle

    2006-01-01

    Repair of mature skeletal muscle is mediated by adult muscle progenitors. Satellite cells have long been recognized as playing a major role in muscle repair, whereas side population (SP) cells have more recently been identified as contributing to this process. The developmental source of these two progenitor populations has been considerably debated. We explicitly tested and quantified the contribution of embryonic somitic cells to these progenitor populations. Chick somitic cells were labeled by using replication-defective retroviruses or quail/chick chimeras, and mouse cells were labeled by crossing somite-specific, Pax3-derived Cre driver lines with a Cre-dependent reporter line. We show that the majority of, if not all, limb muscle satellite cells arise from cells expressing Pax3 specifically in the hypaxial somite and their migratory derivatives. We also find that a significant number of, but not all, limb muscle SP cells are derived from the hypaxial somite. Notably, the heterogeneity in the developmental origin of SP cells is reflected in their functional heterogeneity; somitically derived SP cells are intrinsically more myogenic than nonsomitically derived ones. Thus, we show that the somites, which supply embryonic and fetal myoblasts, are also an important source of highly myogenic adult muscle progenitors. PMID:16418263

  11. Cycle training modulates satellite cell and transcriptional responses to a bout of resistance exercise.

    PubMed

    Murach, Kevin A; Walton, R Grace; Fry, Christopher S; Michaelis, Sami L; Groshong, Jason S; Finlin, Brian S; Kern, Philip A; Peterson, Charlotte A

    2016-09-01

    This investigation evaluated whether moderate-intensity cycle ergometer training affects satellite cell and molecular responses to acute maximal concentric/eccentric resistance exercise in middle-aged women. Baseline and 72 h postresistance exercise vastus lateralis biopsies were obtained from seven healthy middle-aged women (56 ± 5 years, BMI 26 ± 1, VO2max 27 ± 4) before and after 12 weeks of cycle training. Myosin heavy chain (MyHC) I- and II-associated satellite cell density and cross-sectional area was determined via immunohistochemistry. Expression of 93 genes representative of the muscle-remodeling environment was also measured via NanoString. Overall fiber size increased ~20% with cycle training (P = 0.052). MyHC I satellite cell density increased 29% in response to acute resistance exercise before endurance training and 50% with endurance training (P < 0.05). Following endurance training, MyHC I satellite cell density decreased by 13% in response to acute resistance exercise (acute resistance × training interaction, P < 0.05). Genes with an interaction effect tracked with satellite cell behavior, increasing in the untrained state and decreasing in the endurance trained state in response to resistance exercise. Similar satellite cell and gene expression response patterns indicate coordinated regulation of the muscle environment to promote adaptation. Moderate-intensity endurance cycle training modulates the response to acute resistance exercise, potentially conditioning the muscle for more intense concentric/eccentric activity. These results suggest that cycle training is an effective endurance exercise modality for promoting growth in middle-aged women, who are susceptible to muscle mass loss with progressing age.

  12. Soil moisture active passive (SMAP) satellite status and cal/val activities

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Soil Moisture Active Passive (SMAP) satellite will be launched by the National Aeronautics and Space Administration in November 2014. This satellite is the culmination of basic research and applications development over the past thirty years. During most of this period, research and development ...

  13. Effects of 28 days of resistance exercise and consuming a commercially available pre-workout supplement, NO-Shotgun®, on body composition, muscle strength and mass, markers of satellite cell activation, and clinical safety markers in males

    PubMed Central

    Shelmadine, Brian; Cooke, Matt; Buford, Thomas; Hudson, Geoffrey; Redd, Liz; Leutholtz, Brian; Willoughby, Darryn S

    2009-01-01

    Purpose This study determined the effects of 28 days of heavy resistance exercise combined with the nutritional supplement, NO-Shotgun®, on body composition, muscle strength and mass, markers of satellite cell activation, and clinical safety markers. Methods Eighteen non-resistance-trained males participated in a resistance training program (3 × 10-RM) 4 times/wk for 28 days while also ingesting 27 g/day of placebo (PL) or NO-Shotgun® (NO) 30 min prior to exercise. Data were analyzed with separate 2 × 2 ANOVA and t-tests (p < 0.05). Results Total body mass was increased in both groups (p = 0.001), but without any significant increases in total body water (p = 0.77). No significant changes occurred with fat mass (p = 0.62); however fat-free mass did increase with training (p = 0.001), and NO was significantly greater than PL (p = 0.001). Bench press strength for NO was significantly greater than PL (p = 0.003). Myofibrillar protein increased with training (p = 0.001), with NO being significantly greater than PL (p = 0.019). Serum IGF-1 (p = 0.046) and HGF (p = 0.06) were significantly increased with training and for NO HGF was greater than PL (p = 0.002). Muscle phosphorylated c-met was increased with training for both groups (p = 0.019). Total DNA was increased in both groups (p = 0.006), while NO was significantly greater than PL (p = 0.038). For DNA/protein, PL was decreased and NO was not changed (p = 0.014). All of the myogenic regulatory factors were increased with training; however, NO was shown to be significantly greater than PL for Myo-D (p = 0.008) and MRF-4 (p = 0.022). No significant differences were located for any of the whole blood and serum clinical chemistry markers (p > 0.05). Conclusion When combined with heavy resistance training for 28 days, NO-Shotgun® is not associated with any negative side effects, nor does it abnormally impact any of the clinical chemistry markers. Rather, NO-Shotgun® effectively increases muscle strength and mass

  14. Nitric oxide reverses prednisolone-induced inactivation of muscle satellite cells.

    PubMed

    Betters, Jenna L; Long, Jodi H D; Howe, Kathleen S; Braith, Randy W; Soltow, Quinlyn A; Lira, Vitor A; Criswell, David S

    2008-02-01

    Long-term corticosteroid therapy causes myopathy and can inhibit regeneration of skeletal muscle. Therefore, we hypothesized that corticosteroid exposure reduces satellite cell activity in skeletal myofibers. Male Swiss-Webster mice were injected daily for 8 weeks with prednisolone (GC) or vehicle (control). Single myofibers were isolated from the gastrocnemius, centrifuged to mechanically activate satellite cells, and maintained in culture for 48 h. Both constitutive nitric oxide synthase (NOS) isoforms were reduced in muscle by GC treatment (nNOS: -30%, eNOS: -34%). Fewer myogenic (myoD+) cells emanated from GC myofibers compared to control (-61%, P < 0.05). Supplementation of culture media with the nitric oxide donor, diethylenetriamine NONOate (DETA-NO; 5-50 microM), caused a dose-dependent increase in the number of myoD+ cells arising from both control and GC myofibers (P < 0.05), and 10 and 50 microM DETA-NO eliminated the GC-induced deficit in myogenic cells (P > 0.05). Therefore, supplementation of GC myofibers with DETA-NO restores satellite cell activity to control levels. Nitric oxide production could be an important therapeutic target for the prevention of corticosteroid myopathy.

  15. The effect of nutritional status and myogenic satellite cell age on turkey satellite cell proliferation, differentiation, and expression of myogenic transcriptional regulatory factors and heparan sulfate proteoglycans syndecan-4 and glypican-1.

    PubMed

    Harthan, Laura B; McFarland, Douglas C; Velleman, Sandra G

    2014-01-01

    Posthatch satellite cell mitotic activity is a critical component of muscle development and growth. Satellite cells are myogenic stem cells that can be induced by nutrition to follow other cellular developmental pathways, and whose mitotic activity declines with age. The objective of the current study was to determine the effect of restricting protein synthesis on the proliferation and differentiation, expression of myogenic transcriptional regulatory factors myogenic determination factor 1, myogenin, and myogenic regulatory factor 4, and expression of the heparan sulfate proteoglycans syndecan-4 and glypican-1 in satellite cells isolated from 1-d-, 7-wk-, and 16-wk-old turkey pectoralis major muscle (1 d, 7 wk, and 16 wk cells, respectively) by using variable concentrations of Met and Cys. Four Met concentrations-30 (control), 7.5, 3, or 0 mg/L with 3.2 mg/L of Cys per 1 mg/L of Met-were used for culture of satellite cells to determine the effect of nutrition and age on satellite cell behavior during proliferation and differentiation. Proliferation was reduced by lower Met and Cys concentrations in all ages at 96 h of proliferation. Differentiation was increased in the 1 d Met-restricted cells, whereas the 7 wk cells treated with 3 mg/L of Met had decreased differentiation. Reduced Met and Cys levels from the control did not significantly affect the 16 wk cells at 72 h of differentiation. However, medium with no Met or Cys suppressed differentiation at all ages. The expression of myogenic determination factor 1, myogenin, myogenic regulatory factor 4, syndecan-4, and glypican-1 was differentially affected by age and Met or Cys treatment. These data demonstrate the age-specific manner in which turkey pectoralis major muscle satellite cells respond to nutritional availability and the importance of defining optimal nutrition to maximize satellite cell proliferation and differentiation for subsequent muscle mass accretion.

  16. Isolation of satellite cells from single muscle fibers from young, aged, or dystrophic muscles.

    PubMed

    Di Foggia, Valentina; Robson, Lesley

    2012-01-01

    Skeletal muscle contains an identified resident stem cell population called the satellite cells. This cell is responsible for the majority of the postnatal growth and regenerative potential of skeletal muscle. Other cells do contribute to skeletal muscle regeneration and in cultures of minced whole muscle these cells are cultured along with the satellite cells and it is impossible to dissect out their contribution compared to the satellite cells. Therefore, a method to culture pure satellite cells has been developed to study the signaling pathways that control their proliferation and differentiation. In our studies into the role of the resident myogenic stem cells in regeneration, myopathic conditions, and aging, we have optimized the established techniques that already exist to isolate pure satellite cell cultures from single muscle fibers. We have successfully isolated satellite cells from young adults through to 24-month-old muscles and obtained populations of cells that we are studying for the signaling events that regulate their proliferative potential.

  17. Recent Developments of Regenerative Fuel Cell Systems for Satellites

    NASA Astrophysics Data System (ADS)

    Farnes, Jarle; Vik, Arild; Bokach, Dmitry; Svendsen, Tjalve; Schautz, Max; Geneste, Xavier

    2014-08-01

    Next generation telecommunication satellites will demand increasingly more power. Power levels of 30 kW or more are foreseen for the next 10 years. Battery technology that can sustain 30 kW for eclipse lengths of up to 72 minutes will represent a major impact on the total mass of the satellite, even with new Li-ion battery technologies. Regenerative fuel cell systems (RFCS) were identified years ago as a possible alternative to rechargeable batteries. CMR Prototech has investigated this technology in a series of projects initiated by ESA focusing on both the essential fuel cell technology, demonstration of cycle performance of a RFCS, corresponding to 15 years in orbit, as well as the very important reactants storage systems. This paper includes the main results from this work from the past 5 years.

  18. An active attitude control system for a drag sail satellite

    NASA Astrophysics Data System (ADS)

    Steyn, Willem Herman; Jordaan, Hendrik Willem

    2016-11-01

    The paper describes the development and simulation results of a full ADCS subsystem for the deOrbitSail drag sail mission. The deOrbitSail satellite was developed as part of an European FP7 collaboration research project. The satellite was launched and commissioning started on 10th July 2015. Various new actuators and sensors designed for this mission will be presented. The deOrbitSail satellite is a 3U CubeSat to deploy a 4 by 4 m drag sail from an initial 650 km circular polar low earth orbit. With an active attitude control system it will be shown that by maximising the drag force, the expected de-orbiting period from the initial altitude will be less than 50 days. A future application of this technology will be the use of small drag sails as low-cost devices to de-orbit LEO satellites, when they have reached their end of life, without having to use expensive propulsion systems. Simulation and Hardware-in-Loop experiments proved the feasibility of the proposed attitude control system. A magnetic-only control approach using a Y-Thomson spin, is used to detumble the 3U Cubesat with stowed sail and subsequently to 3-axis stabilise the satellite to be ready for the final deployment phase. Minituarised torquer rods, a nano-sized momentum wheel, attitude sensor hardware (magnetometer, sun, earth) developed for this phase will be presented. The final phase will be to deploy and 3-axis stabilise the drag sail normal to the satellite's velocity vector, using a combined Y-momentum wheel and magnetic controller. The design and performance improvements when using a 2-axis translation stage to adjust the sail centre-of-pressure to satellite centre-of-mass offset, will also be discussed, although for launch risk reasons this stage was not included in the final flight configuration. To accurately determine the drag sail's attitude during the sunlit part of the orbit, an accurate wide field of view dual sensor to measure both the sun and nadir vector direction was developed for

  19. Sulforaphane causes a major epigenetic repression of myostatin in porcine satellite cells.

    PubMed

    Fan, Huitao; Zhang, Rui; Tesfaye, Dawit; Tholen, Ernst; Looft, Christian; Hölker, Michael; Schellander, Karl; Cinar, Mehmet Ulas

    2012-12-01

    Satellite cells function as skeletal muscle stem cells to support postnatal muscle growth and regeneration following injury or disease. There is great promise for the improvement of muscle performance in livestock and for the therapy of muscle pathologies in humans by the targeting of myostatin (MSTN) in this cell population. Human diet contains many histone deacetylase (HDAC) inhibitors, such as the bioactive component sulforaphane (SFN), whose epigenetic effects on MSTN gene in satellite cells are unknown. Therefore, we aimed to investigate the epigenetic influences of SFN on the MSTN gene in satellite cells. The present work provides the first evidence, which is distinct from the effects of trichostatin A (TSA), that SFN supplementation in vitro not only acts as a HDAC inhibitor but also as a DNA methyltransferase (DNMT) inhibitor in porcine satellite cells. Compared with TSA and 5-aza-2'-deoxycytidine (5-aza-dC), SFN treatment significantly represses MSTN expression, accompanied by strongly attenuated expression of negative feedback inhibitors of the MSTN signaling pathway. miRNAs targeting MSTN are not implicated in posttranscriptional regulation of MSTN. Nevertheless, a weakly enriched myoblast determination (MyoD) protein associated with diminished histone acetylation in the MyoD binding site located in the MSTN promoter region may contribute to the transcriptional repression of MSTN by SFN. These findings reveal a new mode of epigenetic repression of MSTN by the bioactive compound SFN. This novel pharmacological, biological activity of SFN in satellite cells may thus allow for the development of novel approaches to weaken the MSTN signaling pathway, both for therapies of human skeletal muscle disorders and for livestock production improvement.

  20. Supplementary active stabilization of nonrigid gravity gradient satellites

    NASA Technical Reports Server (NTRS)

    Keat, J. E.

    1972-01-01

    The use of active control for stability augmentation of passive gravity gradient satellites is investigated. The reaction jet method of control is the main interest. Satellite nonrigidity is emphasized. The reduction in the Hamiltonian H is used as a control criteria. The velocities, relative to local vertical, of the jets along their force axes are shown to be of fundamental significance. A basic control scheme which satisfies the H reduction criteria is developed. Each jet is fired when its velocity becomes appropriately large. The jet is de-energized when velocity reaches zero. Firing constraints to preclude orbit alteration may be needed. Control is continued until H has been minimized. This control policy is investigated using impulse and rectangular pulse models of the jet outputs.

  1. Leucine Promotes Proliferation and Differentiation of Primary Preterm Rat Satellite Cells in Part through mTORC1 Signaling Pathway.

    PubMed

    Dai, Jie-Min; Yu, Mu-Xue; Shen, Zhen-Yu; Guo, Chu-Yi; Zhuang, Si-Qi; Qiu, Xiao-Shan

    2015-05-08

    Signaling through the mammalian target of rapamycin (mTOR) in response to leucine modulates many cellular and developmental processes. However, in the context of satellite cell proliferation and differentiation, the role of leucine and mTORC1 is less known. This study investigates the role of leucine in the process of proliferation and differentiation of primary preterm rat satellite cells, and the relationship with mammalian target of rapamycin complex 1 (mTORC1) activation. Dissociation of primary satellite cells occurred with type I collagenase and trypsin, and purification, via different speed adherence methods. Satellite cells with positive expression of Desmin were treated with leucine and rapamycin. We observed that leucine promoted proliferation and differentiation of primary satellite cells and increased the phosphorylation of mTOR. Rapamycin inhibited proliferation and differentiation, as well as decreased the phosphorylation level of mTOR. Furthermore, leucine increased the expression of MyoD and myogenin while the protein level of MyoD decreased due to rapamycin. However, myogenin expressed no affect by rapamycin. In conclusion, leucine may up-regulate the activation of mTORC1 to promote proliferation and differentiation of primary preterm rat satellite cells. We have shown that leucine promoted the differentiation of myotubes in part through the mTORC1-MyoD signal pathway.

  2. Measuring thermal budgets of active volcanoes by satellite remote sensing

    NASA Technical Reports Server (NTRS)

    Glaze, L.; Francis, P. W.; Rothery, D. A.

    1989-01-01

    Thematic Mapper measurements of the total radiant energy flux Q at Lascar volcano in north Chile for December 1984 are reported. The results are consistent with the earlier suggestion that a lava lake is the source of a reported thermal budget anomaly, and with values for 1985-1986 that are much lower, suggesting that fumarolic activity was then a more likely heat source. The results show that satellite remote sensing may be used to monitor the activity of a volcano quantitatively, in a way not possible by conventional ground studies, and may provide a method for predicting eruptions.

  3. Regenerative fuel cell study for satellites in GEO orbit

    NASA Technical Reports Server (NTRS)

    Vandine, Leslie; Gonzalez-Sanabria, Olga; Levy, Alexander

    1987-01-01

    The results of a 12 month study to identify high performance regenerative hydrogen-oxygen fuel cell concepts for geosynchronous satellite application are summarized. Emphasis was placed on concepts with the potential for high energy density and passive means for water and heat management to maximize system reliability. Both polymer membrane and alkaline electrolyte fuel cells were considered, with emphasis on the alkaline cell because of its high performance, advanced state of development, and proven ability to operate in a launch and space environment. Three alkaline system concepts were studied. Results indicate that using near term technology energy densities between 46 and 52 watt-hour/lb can be achieved at efficiencies of 55 percent. Using advanced light weight cell construction which was achieved in experimental cells, composite tankage material for the reactant gases and the reversible stack concept, system energy densities of 115 watt-hours/lb can be projected.

  4. Muscle Interstitial Cells: A Brief Field Guide to Non-satellite Cell Populations in Skeletal Muscle.

    PubMed

    Tedesco, Francesco Saverio; Moyle, Louise A; Perdiguero, Eusebio

    2017-01-01

    Skeletal muscle regeneration is mainly enabled by a population of adult stem cells known as satellite cells. Satellite cells have been shown to be indispensable for adult skeletal muscle repair and regeneration. In the last two decades, other stem/progenitor cell populations resident in the skeletal muscle interstitium have been identified as "collaborators" of satellite cells during regeneration. They also appear to have a key role in replacing skeletal muscle with adipose, fibrous, or bone tissue in pathological conditions. Here, we review the role and known functions of these different interstitial skeletal muscle cell types and discuss their role in skeletal muscle tissue homeostasis, regeneration, and disease, including their therapeutic potential for cell transplantation protocols.

  5. 17β-Estradiol and testosterone in sarcopenia: Role of satellite cells.

    PubMed

    La Colla, Anabela; Pronsato, Lucía; Milanesi, Lorena; Vasconsuelo, Andrea

    2015-11-01

    The loss of muscle mass and strength with aging, referred to as sarcopenia, is a prevalent condition among the elderly. Although the molecular mechanisms underlying sarcopenia are unclear, evidence suggests that an age-related acceleration of myocyte loss via apoptosis might be responsible for muscle perfomance decline. Interestingly, sarcopenia has been associated to a deficit of sex hormones which decrease upon aging. The skeletal muscle ability to repair and regenerate itself would not be possible without satellite cells, a subpopulation of cells that remain quiescent throughout life. They are activated in response to stress, enabling them to guide skeletal muscle regeneration. Thus, these cells could be a key factor to overcome sarcopenia. Of importance, satellite cells are 17β-estradiol (E2) and testosterone (T) targets. In this review, we summarize potential mechanisms through which these hormones regulate satellite cells activation during skeletal muscle regeneration in the elderly. The advance in its understanding will help to the development of potential therapeutic agents to alleviate and treat sarcopenia and other related myophaties.

  6. The effect of temperature on apoptosis and adipogenesis on skeletal muscle satellite cells derived from different muscle types

    PubMed Central

    Harding, Rachel L; Clark, Daniel L; Halevy, Orna; Coy, Cynthia S; Yahav, Shlomo; Velleman, Sandra G

    2015-01-01

    Satellite cells are multipotential stem cells that mediate postnatal muscle growth and respond differently to temperature based upon aerobic versus anaerobic fiber-type origin. The objective of this study was to determine how temperatures below and above the control, 38°C, affect the fate of satellite cells isolated from the anaerobic pectoralis major (p. major) or mixed fiber biceps femoris (b. femoris). At all sampling times, p. major and b. femoris cells accumulated less lipid when incubated at low temperatures and more lipid at elevated temperatures compared to the control. Satellite cells isolated from the p. major were more sensitive to temperature as they accumulated more lipid at elevated temperatures compared to b. femoris cells. Expression of adipogenic genes, CCAAT/enhancer-binding protein β (C/EBPβ) and proliferator-activated receptor gamma (PPARγ) were different within satellite cells isolated from the p. major or b. femoris. At 72 h of proliferation, C/EBPβ expression increased with increasing temperature in both cell types, while PPARγ expression decreased with increasing temperature in p. major satellite cells. At 48 h of differentiation, both C/EBPβ and PPARγ expression increased in the p. major and decreased in the b. femoris, with increasing temperature. Flow cytometry measured apoptotic markers for early apoptosis (Annexin-V-PE) or late apoptosis (7-AAD), showing less than 1% of apoptotic satellite cells throughout all experimental conditions, therefore, apoptosis was considered biologically not significant. The results support that anaerobic p. major satellite cells are more predisposed to adipogenic conversion than aerobic b. femoris cells when thermally challenged. PMID:26341996

  7. The effect of temperature on apoptosis and adipogenesis on skeletal muscle satellite cells derived from different muscle types.

    PubMed

    Harding, Rachel L; Clark, Daniel L; Halevy, Orna; Coy, Cynthia S; Yahav, Shlomo; Velleman, Sandra G

    2015-09-01

    Satellite cells are multipotential stem cells that mediate postnatal muscle growth and respond differently to temperature based upon aerobic versus anaerobic fiber-type origin. The objective of this study was to determine how temperatures below and above the control, 38°C, affect the fate of satellite cells isolated from the anaerobic pectoralis major (p. major) or mixed fiber biceps femoris (b. femoris). At all sampling times, p. major and b. femoris cells accumulated less lipid when incubated at low temperatures and more lipid at elevated temperatures compared to the control. Satellite cells isolated from the p. major were more sensitive to temperature as they accumulated more lipid at elevated temperatures compared to b. femoris cells. Expression of adipogenic genes, CCAAT/enhancer-binding protein β (C/EBPβ) and proliferator-activated receptor gamma (PPARγ) were different within satellite cells isolated from the p. major or b. femoris. At 72 h of proliferation, C/EBPβ expression increased with increasing temperature in both cell types, while PPARγ expression decreased with increasing temperature in p. major satellite cells. At 48 h of differentiation, both C/EBPβ and PPARγ expression increased in the p. major and decreased in the b. femoris, with increasing temperature. Flow cytometry measured apoptotic markers for early apoptosis (Annexin-V-PE) or late apoptosis (7-AAD), showing less than 1% of apoptotic satellite cells throughout all experimental conditions, therefore, apoptosis was considered biologically not significant. The results support that anaerobic p. major satellite cells are more predisposed to adipogenic conversion than aerobic b. femoris cells when thermally challenged.

  8. Development of a satellite flywheel family operating on one active axis magnetic bearings

    NASA Technical Reports Server (NTRS)

    Poubeau, P. C.

    1977-01-01

    Magnetic bearings with radial passive centering and axial active control of the rotor position are described in terms of optimization for satellite flywheel applications and kinetic storage of energy for satellites.

  9. Brain and muscle Arnt-like 1 promotes skeletal muscle regeneration through satellite cell expansion

    SciTech Connect

    Chatterjee, Somik; Yin, Hongshan; Nam, Deokhwa; Li, Yong; Ma, Ke

    2015-02-01

    Circadian clock is an evolutionarily conserved timing mechanism governing diverse biological processes and the skeletal muscle possesses intrinsic functional clocks. Interestingly, although the essential clock transcription activator, Brain and muscle Arnt-like 1 (Bmal1), participates in maintenance of muscle mass, little is known regarding its role in muscle growth and repair. In this report, we investigate the in vivo function of Bmal1 in skeletal muscle regeneration using two muscle injury models. Bmal1 is highly up-regulated by cardiotoxin injury, and its genetic ablation significantly impairs regeneration with markedly suppressed new myofiber formation and attenuated myogenic induction. A similarly defective regenerative response is observed in Bmal1-null mice as compared to wild-type controls upon freeze injury. Lack of satellite cell expansion accounts for the regeneration defect, as Bmal1{sup −/−} mice display significantly lower satellite cell number with nearly abolished induction of the satellite cell marker, Pax7. Furthermore, satellite cell-derived primary myoblasts devoid of Bmal1 display reduced growth and proliferation ex vivo. Collectively, our results demonstrate, for the first time, that Bmal1 is an integral component of the pro-myogenic response that is required for muscle repair. This mechanism may underlie its role in preserving adult muscle mass and could be targeted therapeutically to prevent muscle-wasting diseases. - Highlights: • Bmal1 is highly inducible by muscle injury and myogenic stimuli. • Genetic ablation of Bmal1 significantly impairs muscle regeneration. • Bmal1 promotes satellite cell expansion during muscle regeneration. • Bmal1-deficient primary myoblasts display attenuated growth and proliferation.

  10. Transcriptional Activation of Pericentromeric Satellite Repeats and Disruption of Centromeric Clustering upon Proteasome Inhibition.

    PubMed

    Natisvili, Theona; Yandim, Cihangir; Silva, Raquel; Emanuelli, Giulia; Krueger, Felix; Nageshwaran, Sathiji; Festenstein, Richard

    2016-01-01

    Heterochromatinisation of pericentromeres, which in mice consist of arrays of major satellite repeats, are important for centromere formation and maintenance of genome stability. The dysregulation of this process has been linked to genomic stress and various cancers. Here we show in mice that the proteasome binds to major satellite repeats and proteasome inhibition by MG132 results in their transcriptional de-repression; this de-repression is independent of cell-cycle perturbation. The transcriptional activation of major satellite repeats upon proteasome inhibition is accompanied by delocalisation of heterochromatin protein 1 alpha (HP1α) from chromocentres, without detectable change in the levels of histone H3K9me3, H3K4me3, H3K36me3 and H3 acetylation on the major satellite repeats. Moreover, inhibition of the proteasome was found to increase the number of chromocentres per cell, reflecting destabilisation of the chromocentre structures. Our findings suggest that the proteasome plays a role in maintaining heterochromatin integrity of pericentromeres.

  11. Transcriptional Activation of Pericentromeric Satellite Repeats and Disruption of Centromeric Clustering upon Proteasome Inhibition

    PubMed Central

    Natisvili, Theona; Yandim, Cihangir; Silva, Raquel; Emanuelli, Giulia; Krueger, Felix; Nageshwaran, Sathiji; Festenstein, Richard

    2016-01-01

    Heterochromatinisation of pericentromeres, which in mice consist of arrays of major satellite repeats, are important for centromere formation and maintenance of genome stability. The dysregulation of this process has been linked to genomic stress and various cancers. Here we show in mice that the proteasome binds to major satellite repeats and proteasome inhibition by MG132 results in their transcriptional de-repression; this de-repression is independent of cell-cycle perturbation. The transcriptional activation of major satellite repeats upon proteasome inhibition is accompanied by delocalisation of heterochromatin protein 1 alpha (HP1α) from chromocentres, without detectable change in the levels of histone H3K9me3, H3K4me3, H3K36me3 and H3 acetylation on the major satellite repeats. Moreover, inhibition of the proteasome was found to increase the number of chromocentres per cell, reflecting destabilisation of the chromocentre structures. Our findings suggest that the proteasome plays a role in maintaining heterochromatin integrity of pericentromeres. PMID:27806100

  12. MSFC solar activity predictions for satellite orbital lifetime estimation

    NASA Technical Reports Server (NTRS)

    Fuler, H. C.; Lundquist, C. A.; Vaughan, W. W.

    1979-01-01

    The procedure to predict solar activity indexes for use in upper atmosphere density models is given together with an example of the performance. The prediction procedure employs a least square linear regression model to generate the predicted smoothed vinculum R sub 13 and geomagnetic vinculum A sub p(13) values. Linear regression equations are then employed to compute corresponding vinculum F sub 10.7(13) solar flux values from the predicted vinculum R sub 13 values. The output is issued principally for satellite orbital lifetime estimations.

  13. Nandrolone decanoate increases satellite cell numbers in the chicken pectoralis muscle.

    PubMed

    Allouh, Mohammed Z; Rosser, Benjamin W C

    2010-02-01

    The anabolic androgenic steroid nandrolone decanoate has minimal androgenic effects and, thus, is widely used to induce muscle hypertrophy in both patients and athletes. Although increases in satellite cell numbers and satellite cells giving rise to new myonuclei are associated with hypertrophy in many experimental models, the relationship between nandrolone and satellite cells is poorly understood. Here we test the hypothesis that nandrolone administration is associated with an increase in satellite cell numbers in muscle. Nandrolone was injected at weekly intervals for four weeks into the right pectoralis muscle of female white leghorn chickens aged 63 days post hatch. Age/size/sex matched control birds received saline injections. The contralateral pectoralis was excised for study from each control and nandrolone treated bird. An antibody against Pax7 and immunocytochemical techniques were used to identify satellite cells. Nandrolone significantly increased mean pectoralis mass by approximately 22%, and mean fiber diameter by about 24%. All satellite cell indices that were quantified increased significantly in chicken pectoralis with administration of nandrolone. Nandrolone injected birds had on average higher satellite cell frequencies (#SC nuclei/all nuclei within basal lamina), number of satellite cells per millimeter of fiber, and satellite cell concentrations (closer together). Myonuclei were further apart (less concentrated) in nandrolone injected muscle. However, an overall increase in myonuclear numbers was revealed by a significantly greater mean number of myonuclei per millimeter of fiber in nandrolone injected muscle. Our results suggest that satellite cells may be key cellular vectors for nandrolone induced muscle fiber hypertrophy.

  14. Fibromodulin: a master regulator of myostatin controlling progression of satellite cells through a myogenic program.

    PubMed

    Lee, Eun Ju; Jan, Arif Tasleem; Baig, Mohammad Hassan; Ashraf, Jalaluddin Mohammad; Nahm, Sang-Soep; Kim, Yong-Woon; Park, So-Young; Choi, Inho

    2016-08-01

    Differentiation of muscle satellite cells (MSCs) involves interaction of the proteins present in the extracellular matrix (ECM) with MSCs to regulate their activity, and therefore phenotype. Herein, we report fibromodulin (FMOD), a member of the proteoglycan family participating in the assembly of ECM, as a novel regulator of myostatin (MSTN) during myoblast differentiation. In addition to having a pronounced effect on the expression of myogenic marker genes [myogenin (MYOG) and myosin light chain 2 (MYL2)], FMOD was found to maintain the transcriptional activity of MSTN Moreover, coimmunoprecipitation and in silico studies performed to investigate the interaction of FMOD helped confirm that it antagonizes MSTN function by distorting its folding and preventing its binding to activin receptor type IIB. Furthermore, in vivo studies revealed that FMOD plays an active role in healing by increasing satellite cell recruitment to sites of injury. Together, these findings disclose a hitherto unrecognized regulatory role for FMOD in MSCs and highlight new mechanisms whereby FMOD circumvents the inhibitory effects of MSTN and triggers myoblast differentiation. These findings offer a basis for the design of novel MSTN inhibitors that promote muscle regeneration after injury or for the development of pharmaceutical agents for the treatment of different muscle atrophies.-Lee, E. J., Jan, A. T., Baig, M. H., Ashraf, J. M., Nahm, S.-S., Kim, Y.-W., Park, S.-Y., Choi, I. Fibromodulin: a master regulator of myostatin controlling progression of satellite cells through a myogenic program.

  15. Regenerative fuel cell study for satellites in GEO orbit

    NASA Technical Reports Server (NTRS)

    Levy, Alexander; Vandine, Leslie L.; Stedman, James K.

    1987-01-01

    Summarized are the results of a 12-month study to identify high performance regenerative hydrogen-oxygen fuel cell concepts for geosynchronous satellite application. Emphasis was placed on concepts with the potential for high energy density (W-hr/lb) and passive means for water and heat management to maximize system reliability. Both polymer membrane and alkaline electrolyte fuel cells were considered, with emphasis on the alkaline cell because of its high performance, advanced state of development, and proven ability to operate in a launch and space environment. Three alkaline system concepts were studied. The first, the integrated design, utilized a configuration in which the fuel cell and electrolysis cells are alternately stacked inside a pressure vessel. Product water is transferred by diffusion during electrolysis and waste heat is conducted through the pressure wall, thus using completely passive means for transfer and control. The second alkaline system, the dedicated design, uses a separate fuel cell and electrolysis stack so that each unit can be optimized in size and weight based on its orbital operating period. The third design was a dual function stack configuration, in which each cell can operate in both fuel cell and electrolysis mode, thus eliminating the need for two separate stacks and associated equipment. Results indicate that using near term technology energy densities between 46 and 52 W-hr/lb can be achieved at efficiencies of 55 percent. System densities of 115 W-hr/lb are contemplated.

  16. VES16 Li-Ion Cell For Satellite

    NASA Astrophysics Data System (ADS)

    Remy, S.; Prevot, D.; Reulier, D.; Vigier, F., , Dr.

    2011-10-01

    At a period when LEO satellite market is growing, as well as mission life time requirements, Saft has designed a new Li-ion cell aiming to answer those demanding requirements. This development is conducted with the support and partnership of CNES French agency. This VES16 cell combines benefits and heritage of low capacity MPS Li-ion cells, and advantages of Nickel oxide base Li-ion chemistry of VES100-140-180 cells. After a period of cycling evaluation of the cell with slight electrochemistry differences, an optimized cell design has been frozen and is submitted to a large qualification plan, including characterisations, environmental tests, and life time demonstrations. This paper presents the main BOL characteristics and performances achieved during the qualification program, including electrical, thermal and mechanical characterisations. It will also detail the expected lifetime data, and the key results obtained on VES16 cell in LEO mission cycling configuration. A specific paragraph also includes results in GEO cycling configuration, to highlight that the cell can be also proposed on geostationary spacecraft.

  17. Regenerative fuel cell study for satellites in GEO orbit

    NASA Astrophysics Data System (ADS)

    Levy, Alexander; Vandine, Leslie L.; Stedman, James K.

    1987-07-01

    Summarized are the results of a 12-month study to identify high performance regenerative hydrogen-oxygen fuel cell concepts for geosynchronous satellite application. Emphasis was placed on concepts with the potential for high energy density (W-hr/lb) and passive means for water and heat management to maximize system reliability. Both polymer membrane and alkaline electrolyte fuel cells were considered, with emphasis on the alkaline cell because of its high performance, advanced state of development, and proven ability to operate in a launch and space environment. Three alkaline system concepts were studied. The first, the integrated design, utilized a configuration in which the fuel cell and electrolysis cells are alternately stacked inside a pressure vessel. Product water is transferred by diffusion during electrolysis and waste heat is conducted through the pressure wall, thus using completely passive means for transfer and control. The second alkaline system, the dedicated design, uses a separate fuel cell and electrolysis stack so that each unit can be optimized in size and weight based on its orbital operating period. The third design was a dual function stack configuration, in which each cell can operate in both fuel cell and electrolysis mode, thus eliminating the need for two separate stacks and associated equipment. Results indicate that using near term technology energy densities between 46 and 52 W-hr/lb can be achieved at efficiencies of 55 percent. System densities of 115 W-hr/lb are contemplated.

  18. Hyperhomocysteinemia inhibits satellite cell regenerative capacity through p38 alpha/beta MAPK signaling.

    PubMed

    Veeranki, Sudhakar; Lominadze, David; Tyagi, Suresh C

    2015-07-15

    Chronic failure in maintenance and regeneration of skeletal muscles leads to lower muscle mass (sarcopenia), muscle weakness, and poor response to injury. Evidence suggests that aberrant p38 MAPK signaling undermines the repair process after injury in aged mice. Previous studies have shown that hyperhomocysteinemia (HHcy) has been associated with muscle weakness and lower than normal body weights. However, whether or not HHcy condition also compromises skeletal muscle regenerative capabilities is not clear. In the current study, we show that CBS-/+ mice, a model for HHcy condition, exhibited compromised regenerative function and cell proliferation upon injury. However, there was no significant difference in Pax7 expression levels in the satellite cells from CBS-/+ mouse skeletal muscles. Interestingly, the satellite cells from CBS-/+ mice not only exhibited diminished in vitro proliferative capabilities, but also there was heightened oxidative stress. In addition, there was enhanced p38 MAPK activation as well as p16 and p21 expression in the CBS-/+ mouse satellite cells. Moreover, the C2C12 myoblasts also exhibited higher p38 MAPK activation and p16 expression upon treatment with homocysteine in addition to enhanced ROS presence. Tissue engraftment potential and regeneration after injury were restored to some extent upon treatment with the p38-MAPK inhibitor, SB203580, in the CBS-/+ mice. These results together suggest that HHcy-induced diminished satellite cell proliferation involves excessive oxidative stress and p38 MAPK signaling. Our study further proposes that HHcy is a potential risk factor for elderly frailty, and need to be considered as a therapeutic target while designing the alleviation interventions/postinjury rehabilitation measures for adults with HHcy.

  19. Isolation and characterization of primary skeletal muscle satellite cells from rats.

    PubMed

    Liu, Yuan; Chen, Sifan; Li, Wenxue; Du, Hongyan; Zhu, Wei

    2012-11-01

    The purpose of this study was to isolate and characterize skeletal muscle satellite cells from rats using tissue block culture method. Specific Pathogen Free (SPF) level Sprague-Dawley (SD) rats were used to isolate skeletal muscle satellite cells. Morphology, expression and distribution of α-actin and Desmin within the cytoplasm of skeletal muscle satellite cells were compared with those of C2C12 myoblasts. The results showed that tissue block culturing method achieved robust proliferation and excellent differentiation of skeletal muscle satellite cells. Immunofluorescence and immunohistochemistry results showed that α-actin and Desmin proteins were expressed in the cytoplasm of both skeletal muscle satellite cells and myoblasts. We concluded that tissue block culturing method can obtain highly purified skeletal muscle satellite cells with robust proliferation and excellent differentiation capabilities.

  20. Skeletal muscle satellite cells: background and methods for isolation and analysis in a primary culture system.

    PubMed

    Danoviz, Maria Elena; Yablonka-Reuveni, Zipora

    2012-01-01

    Repair of adult skeletal muscle depends on satellite cells, myogenic stem cells located between the basal lamina and the plasmalemma of the myofiber. Standardized protocols for the isolation and culture of satellite cells are key tools for understanding cell autonomous and extrinsic factors that regulate their performance. Knowledge gained from such studies can contribute important insights to developing strategies for the improvement of muscle repair following trauma and in muscle wasting disorders. This chapter provides an introduction to satellite cell biology and further describes the basic protocol used in our laboratory to isolate and culture satellite cells from adult skeletal muscle. The cell culture conditions detailed herein support proliferation and differentiation of satellite cell progeny and the development of reserve cells, which are thought to reflect the in vivo self-renewal ability of satellite cells. Additionally, this chapter describes our standard immunostaining protocol that allows the characterization of satellite cell progeny by the temporal expression of characteristic transcription factors and structural proteins associated with different stages of myogenic progression. Although emphasis is given here to the isolation and characterization of satellite cells from mouse hindlimb muscles, the protocols are suitable for other muscle types (such as diaphragm and extraocular muscles) and for muscles from other species, including chicken and rat. Altogether, the basic protocols described are straightforward and facilitate the study of diverse aspects of skeletal muscle stem cells.

  1. Inactivation of PPARβ/δ adversely affects satellite cells and reduces postnatal myogenesis.

    PubMed

    Chandrashekar, Preeti; Manickam, Ravikumar; Ge, Xiaojia; Bonala, Sabeera; McFarlane, Craig; Sharma, Mridula; Wahli, Walter; Kambadur, Ravi

    2015-07-15

    Peroxisome proliferator-activated receptor β/δ (PPARβ/δ) is a ubiquitously expressed gene with higher levels observed in skeletal muscle. Recently, our laboratory showed (Bonala S, Lokireddy S, Arigela H, Teng S, Wahli W, Sharma M, McFarlane C, Kambadur R. J Biol Chem 287: 12935-12951, 2012) that PPARβ/δ modulates myostatin activity to induce myogenesis in skeletal muscle. In the present study, we show that PPARβ/δ-null mice display reduced body weight, skeletal muscle weight, and myofiber atrophy during postnatal development. In addition, a significant reduction in satellite cell number was observed in PPARβ/δ-null mice, suggesting a role for PPARβ/δ in muscle regeneration. To investigate this, tibialis anterior muscles were injured with notexin, and muscle regeneration was monitored on days 3, 5, 7, and 28 postinjury. Immunohistochemical analysis revealed an increased inflammatory response and reduced myoblast proliferation in regenerating muscle from PPARβ/δ-null mice. Histological analysis confirmed that the regenerated muscle fibers of PPARβ/δ-null mice maintained an atrophy phenotype with reduced numbers of centrally placed nuclei. Even though satellite cell numbers were reduced before injury, satellite cell self-renewal was found to be unaffected in PPARβ/δ-null mice after regeneration. Previously, our laboratory had showed (Bonala S, Lokireddy S, Arigela H, Teng S, Wahli W, Sharma M, McFarlane C, Kambadur R. J Biol Chem 287: 12935-12951, 2012) that inactivation of PPARβ/δ increases myostatin signaling and inhibits myogenesis. Our results here indeed confirm that inactivation of myostatin signaling rescues the atrophy phenotype and improves muscle fiber cross-sectional area in both uninjured and regenerated tibialis anterior muscle from PPARβ/δ-null mice. Taken together, these data suggest that absence of PPARβ/δ leads to loss of satellite cells, impaired skeletal muscle regeneration, and postnatal myogenesis. Furthermore, our results

  2. Seven-core active fibre for application in telecommunication satellites

    NASA Astrophysics Data System (ADS)

    Filipowicz, Marta; Napierała, Marek; Murawski, Michał; Ostrowski, Łukasz; Szostkiewicz, Łukasz; Szymański, Michał; Tenderenda, Tadeusz; Anders, Krzysztof; Piramidowicz, Ryszard; Wójcik, Grzegorz; Makara, Mariusz; Poturaj, Krzysztof; Mergo, Paweł; Nasiłowski, Tomasz

    2015-12-01

    The use of optical elements and other photonic components makes it possible to overcome telecommunication satellite's bottleneck problems such as size and weight reduction. Despite the unquestionable potential of such elements, nowadays they are not widely used in systems operating in space. This is due to many factors, including the fact that space radiation has disruptive influence on optical fibre. Namely it introduces additional radiation induced attenuation (RIA) that significantly lowers efficiency of optical fibre based systems. However, there is a possibility to produce radiation-hardened (rad-hard) components. One of them is seven core erbium-doped active fibre (MC-EDF) for fibre amplifiers in satellites that we have been developing. In this paper we present a detailed description of seven core structure design as well as experimental results. We report that average gain of 20 dB in C-band with noise figure of 5.8 dB was obtained. We also confirmed that low crosstalk value for a multicore fibre amplifier based on our fibre can be achieved.

  3. Muscle satellite cells are a functionally heterogeneous population in both somite-derived and branchiomeric muscles.

    PubMed

    Ono, Yusuke; Boldrin, Luisa; Knopp, Paul; Morgan, Jennifer E; Zammit, Peter S

    2010-01-01

    Skeletal muscles of body and limb are derived from somites, but most head muscles originate from cranial mesoderm. The resident stem cells of muscle are satellite cells, which have the same embryonic origin as the muscle in which they reside. Here, we analysed satellite cells with a different ontology, comparing those of the extensor digitorum longus (EDL) of the limb with satellite cells from the masseter of the head. Satellite cell-derived myoblasts from MAS and EDL muscles had distinct gene expression profiles and masseter cells usually proliferated more and differentiated later than those from EDL. When transplanted, however, masseter-derived satellite cells regenerated limb muscles as efficiently as those from EDL. Clonal analysis showed that functional properties differed markedly between satellite cells: ranging from clones that proliferated extensively and gave rise to both differentiated and self-renewed progeny, to others that divided minimally before differentiating completely. Generally, masseter-derived clones were larger and took longer to differentiate than those from EDL. This distribution in cell properties was preserved in both EDL-derived and masseter-derived satellite cells from old mice, although clones were generally less proliferative. Satellite cells, therefore, are a functionally heterogeneous population, with many occupants of the niche exhibiting stem cell characteristics in both somite-derived and branchiomeric muscles.

  4. Invited Review: Extrinsic regulation of domestic animal-derived myogenic satellite cells II

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The existence of myogenic satellite cells was reported some forty-seven years ago, and, since that time, satellite cell research has flourished. So much new information is generated (daily) on these cells that it can be difficult for individuals to keep abreast of important issues related to the act...

  5. Srf-dependent paracrine signals produced by myofibers control satellite cell-mediated skeletal muscle hypertrophy.

    PubMed

    Guerci, Aline; Lahoute, Charlotte; Hébrard, Sophie; Collard, Laura; Graindorge, Dany; Favier, Maryline; Cagnard, Nicolas; Batonnet-Pichon, Sabrina; Précigout, Guillaume; Garcia, Luis; Tuil, David; Daegelen, Dominique; Sotiropoulos, Athanassia

    2012-01-04

    Adult skeletal muscles adapt their fiber size to workload. We show that serum response factor (Srf) is required for satellite cell-mediated hypertrophic muscle growth. Deletion of Srf from myofibers and not satellite cells blunts overload-induced hypertrophy, and impairs satellite cell proliferation and recruitment to pre-existing fibers. We reveal a gene network in which Srf within myofibers modulates interleukin-6 and cyclooxygenase-2/interleukin-4 expressions and therefore exerts a paracrine control of satellite cell functions. In Srf-deleted muscles, in vivo overexpression of interleukin-6 is sufficient to restore satellite cell proliferation but not satellite cell fusion and overall growth. In contrast cyclooxygenase-2/interleukin-4 overexpression rescue satellite cell recruitment and muscle growth without affecting satellite cell proliferation, identifying altered fusion as the limiting cellular event. These findings unravel a role for Srf in the translation of mechanical cues applied to myofibers into paracrine signals, which in turn will modulate satellite cell functions and support muscle growth.

  6. Communication between neuronal somata and satellite glial cells in sensory ganglia.

    PubMed

    Huang, Li-Yen M; Gu, Yanping; Chen, Yong

    2013-10-01

    Studies of the structural organization and functions of the cell body of a neuron (soma) and its surrounding satellite glial cells (SGCs) in sensory ganglia have led to the realization that SGCs actively participate in the information processing of sensory signals from afferent terminals to the spinal cord. SGCs use a variety ways to communicate with each other and with their enwrapped soma. Changes in this communication under injurious conditions often lead to abnormal pain conditions. "What are the mechanisms underlying the neuronal soma and SGC communication in sensory ganglia?" and "how do tissue or nerve injuries affect the communication?" are the main questions addressed in this review.

  7. BRE facilitates skeletal muscle regeneration by promoting satellite cell motility and differentiation.

    PubMed

    Xiao, Lihai; Lee, Kenneth Ka Ho

    2016-01-06

    The function of the Bre gene in satellite cells was investigated during skeletal muscle regeneration. The tibialis anterior leg muscle was experimentally injured in Bre knockout mutant (BRE-KO) mice. It was established that the accompanying muscle regeneration was impaired as compared with their normal wild-type counterparts (BRE-WT). There were significantly fewer pax7(+) satellite cells and smaller newly formed myofibers present in the injury sites of BRE-KO mice. Bre was required for satellite cell fusion and myofiber formation. The cell fusion index and average length of newly-formed BRE-KO myofibers were found to be significantly reduced as compared with BRE-WT myofibers. It is well established that satellite cells are highly invasive which confers on them the homing ability to reach the muscle injury sites. Hence, we tracked the migratory behavior of these cells using time-lapse microscopy. Image analysis revealed no difference in directionality of movement between BRE-KO and BRE-WT satellite cells but there was a significant decrease in the velocity of BRE-KO cell movement. Moreover, chemotactic migration assays indicated that BRE-KO satellite cells were significantly less responsive to chemoattractant SDF-1α than BRE-WT satellite cells. We also established that BRE normally protects CXCR4 from SDF-1α-induced degradation. In sum, BRE facilitates skeletal muscle regeneration by enhancing satellite cell motility, homing and fusion.

  8. Spiral ganglion degeneration and hearing loss as a consequence of satellite cell death in saposin B-deficient mice.

    PubMed

    Akil, Omar; Sun, Ying; Vijayakumar, Sarath; Zhang, Wujuan; Ku, Tiffany; Lee, Chi-Kyou; Jones, Sherri; Grabowski, Gregory A; Lustig, Lawrence R

    2015-02-18

    Saposin B (Sap B) is an essential activator protein for arylsulfatase A in the hydrolysis of sulfatide, a lipid component of myelin. To study Sap B's role in hearing and balance, a Sap B-deficient (B(-/-)) mouse was evaluated. At both light and electron microscopy (EM) levels, inclusion body accumulation was seen in satellite cells surrounding spiral ganglion (SG) neurons from postnatal month 1 onward, progressing into large vacuoles preceding satellite cell degeneration, and followed by SG degeneration. EM also revealed reduced or absent myelin sheaths in SG neurons from postnatal month 8 onwards. Hearing loss was initially seen at postnatal month 6 and progressed thereafter for frequency-specific stimuli, whereas click responses became abnormal from postnatal month 13 onward. The progressive hearing loss correlated with the accumulation of inclusion bodies in the satellite cells and their subsequent degeneration. Outer hair cell numbers and efferent function measures (distortion product otoacoustic emissions and contralateral suppression) were normal in the B(-/-) mice throughout this period. Alcian blue staining of SGs demonstrated that these inclusion bodies corresponded to sulfatide accumulation. In contrast, changes in the vestibular system were much milder, but caused severe physiologic deficits. These results demonstrate that loss of Sap B function leads to progressive sulfatide accumulation in satellite cells surrounding the SG neurons, leading to satellite cell degeneration and subsequent SG degeneration with a resultant loss of hearing. Relative sparing of the efferent auditory and vestibular neurons suggests that alternate glycosphingolipid metabolic pathways predominate in these other systems.

  9. New insights into the relationship between mIGF-1-induced hypertrophy and Ca2+ handling in differentiated satellite cells.

    PubMed

    Guarnieri, Simone; Morabito, Caterina; Belia, Silvia; Barberi, Laura; Musarò, Antonio; Fanò-Illic, Giorgio; Mariggiò, Maria A

    2014-01-01

    Muscle regeneration involves the activation of satellite cells, is regulated at the genetic and epigenetic levels, and is strongly influenced by gene activation and environmental conditions. The aim of this study was to determine whether the overexpression of mIGF-1 can modify functional features of satellite cells during the differentiation process, particularly in relation to modifications of intracellular Ca2+ handling. Satellite cells were isolated from wild-type and MLC/mIGF-1 transgenic mice. The cells were differentiated in vitro, and morphological analyses, intracellular Ca2+ measurements, and ionic current recordings were performed. mIGF-1 overexpression accelerates satellite cell differentiation and promotes myotube hypertrophy. In addition, mIGF-1 overexpression-induced potentiation of myogenesis triggers both quantitative and qualitative changes to the control of intracellular Ca2+ handling. In particular, the differentiated MLC/mIGF-1 transgenic myotubes have reduced velocity and amplitude of intracellular Ca2+ increases after stimulation with caffeine, KCl and acetylcholine. This appears to be due, at least in part, to changes in the physico-chemical state of the sarcolemma (increased membrane lipid oxidation, increased output currents) and to increased expression of dihydropyridine voltage-operated Ca2+ channels. Interestingly, extracellular ATP and GTP evoke intracellular Ca2+ mobilization to greater extents in the MLC/mIGF-1 transgenic satellite cells, compared to the wild-type cells. These data suggest that these MLC/mIGF-1 transgenic satellite cells are more sensitive to trophic stimuli, which can potentiate the effects of mIGF-1 on the myogenic programme.

  10. Isolation, culture and biological characteristics of multipotent porcine skeletal muscle satellite cells.

    PubMed

    Yang, Jinjuan; Liu, Hao; Wang, Kunfu; Li, Lu; Yuan, Hongyi; Liu, Xueting; Liu, Yingjie; Guan, Weijun

    2017-03-02

    Skeletal muscle has a huge regenerative potential for postnatal muscle growth and repair, which mainly depends on a kind of muscle progenitor cell population, called satellite cell. Nowadays, the majority of satellite cells were obtained from human, mouse, rat and other animals but rarely from pig. In this article, the porcine skeletal muscle satellite cells were isolated and cultured in vitro. The expression of surface markers of satellite cells was detected by immunofluorescence and RT-PCR assays. The differentiation capacity was assessed by inducing satellite cells into adipocytes, myoblasts and osteoblasts. The results showed that satellite cells isolated from porcine tibialis anterior were subcultured up to 12 passages and were positive for Pax7, Myod, c-Met, desmin, PCNA and NANOG but were negative for Myogenin. Satellite cells were also induced to differentiate into adipocytes, osteoblasts and myoblasts, respectively. These findings indicated that porcine satellite cells possess similar biological characteristics of stem cells, which may provide theoretical basis and experimental evidence for potential therapeutic application in the treatment of dystrophic muscle and other muscle injuries.

  11. Low-energy laser irradiation promotes the survival and cell cycle entry of skeletal muscle satellite cells.

    PubMed

    Shefer, Gavriella; Partridge, Terry A; Heslop, Louise; Gross, Jacqueline G; Oron, Uri; Halevy, Orna

    2002-04-01

    Low energy laser irradiation (LELI) has been shown to promote skeletal muscle cell activation and proliferation in primary cultures of satellite cells as well as in myogenic cell lines. Here, we have extended these studies to isolated myofibers. These constitute the minimum viable functional unit of the skeletal muscle, thus providing a close model of in vivo regeneration of muscle tissue. We show that LELI stimulates cell cycle entry and the accumulation of satellite cells around isolated single fibers grown under serum-free conditions and that these effects act synergistically with the addition of serum. Moreover, for the first time we show that LELI promotes the survival of fibers and their adjacent cells, as well as cultured myogenic cells, under serum-free conditions that normally lead to apoptosis. In both systems, expression of the anti-apoptotic protein Bcl-2 was markedly increased, whereas expression of the pro-apoptotic protein BAX was reduced. In culture, these changes were accompanied by a reduction in the expression of p53 and the cyclin-dependent kinase inhibitor p21, reflecting the small decrease in viable cells 24 hours after irradiation. These findings implicate regulation of these factors as part of the protective role of LELI against apoptosis. Taken together, our findings are of critical importance in attempts to improve muscle regeneration following injury.

  12. Evaluation of a satellite constellation for active debris removal

    NASA Astrophysics Data System (ADS)

    Sahara, Hironori

    2014-12-01

    This paper analyzes an example of a three-dimensional constellation of debris removal satellites and proposes an effective constellation using a delta-V analysis that discusses the advisability of rendezvousing satellites with space debris. Lambert's Equation was used to establish a means of analysis to construct a constellation of debris removal satellites, which has a limit of delta-V injection by evaluating the amount of space debris that can be rendezvoused by a certain number of removal satellite. Consequently, we determine a constellation of up to 38 removal satellites for debris removal, where the number of space debris rendezvoused by a single removal satellite is not more than 25, removing up to 584 pieces of debris total. Even if we prepare 38 removal satellites in their respective orbits, it is impossible to remove all of the space debris. Although many removal satellites, over 100 for example, can remove most of the space debris, this method is economically disproportionate. However, we can also see the removal satellites are distributed nearly evenly. Accordingly, we propose a practical two-stage strategy. The first stage is to implement emergent debris removal with the 38 removal satellites. When we find a very high probability of collision between a working satellite and space debris, one of the removal satellites in the constellation previously constructed in orbit initiates a maneuver of emergent debris removal. The second stage is a long-term space debris removal strategy to suppress the increase of space debris derived from collisions among the pieces of space debris. The constellation analyzed in this paper, which consists of the first 38 removal satellites, can remove half of the over 1000 dangerous space debris among others, and then the constellation increases the number of the following removal satellites in steps. At any rate, an adequate orbital configuration and constellation form is very important for both space debris removal and

  13. Skeletal muscle stem cells express anti-apoptotic ErbB receptors during activation from quiescence

    SciTech Connect

    Golding, Jon P. . E-mail: j.p.golding@open.ac.uk; Calderbank, Emma; Partridge, Terence A.; Beauchamp, Jonathan R.

    2007-01-15

    To be effective for tissue repair, satellite cells (the stem cells of adult muscle) must survive the initial activation from quiescence. Using an in vitro model of satellite cell activation, we show that erbB1, erbB2 and erbB3, members of the EGF receptor tyrosine kinase family, appear on satellite cells within 6 h of activation. We show that signalling via erbB2 provides an anti-apoptotic survival mechanism for satellite cells during the first 24 h, as they progress to a proliferative state. Inhibition of erbB2 signalling with AG825 reduced satellite cell numbers, concomitant with elevated caspase-8 activation and TUNEL labelling of apoptotic satellite cells. In serum-free conditions, satellite cell apoptosis could be largely prevented by a mixture of erbB1, erbB3 and erbB4 ligand growth factors, but not by neuregulin alone (erbB3/erbB4 ligand). Furthermore, using inhibitors specific to discrete intracellular signalling pathways, we identify MEK as a pro-apoptotic mediator, and the erbB-regulated factor STAT3 as an anti-apoptotic mediator during satellite cell activation. These results implicate erbB2 signalling in the preservation of a full compliment of satellite cells as they activate in the context of a damaged muscle.

  14. Changes in satellite cells in human skeletal muscle after a single bout of high intensity exercise

    PubMed Central

    Crameri, Regina M; Langberg, Henning; Magnusson, Peter; Jensen, Charlotte H; Schrøder, Henrik Daa; Olesen, Jens L; Suetta, Charlotte; Teisner, Børge; Kjaer, Michael

    2004-01-01

    No studies to date have reported activation of satellite cells in vivo in human muscle after a single bout of high intensity exercise. In this investigation, eight individuals performed a single bout of high intensity exercise with one leg, the contralateral leg being the control. A significant increase in mononuclear cells staining for the neural cell adhesion molecule (N-CAM) and fetal antigen 1 (FA1) were observed within the exercised human vastus lateralis muscle on days 4 and 8 post exercise. In addition, a significant increase in the concentration of the FA1 protein was determined in intramuscular dialysate samples taken from the vastus lateralis muscle of the exercising leg (day 0: 1.89 ± 0.82 ng ml−1; day 2: 1.68 ± 0.37 ng ml−1; day 4: 3.26 ± 1.29 ng ml−1, P < 0.05 versus basal; day 8: 4.68 ± 2.06 ng ml−1, P < 0.05 versus basal and control). No change was noted in the control leg. Despite this increase in N-CAM- and FA1-positive mononuclear cells, an increased expression of myogenin and the neonatal isoform of the myosin heavy chain (MHCn) was not observed. Interestingly, myofibre lesions resulting from extensive damage to the proteins within the myofibre, particularly desmin or dystrophin, were not observed, and hence did not appear to induce the expression of either N-CAM or FA1. We therefore propose that satellite cells can be induced to re-enter the cell growth cycle after a single bout of unaccustomed high intensity exercise. However, a single bout of exercise is not sufficient for the satellite cell to undergo terminal differentiation. PMID:15121802

  15. A myogenic precursor cell that could contribute to regeneration in zebrafish and its similarity to the satellite cell.

    PubMed

    Siegel, Ashley L; Gurevich, David B; Currie, Peter D

    2013-09-01

    The cellular basis for mammalian muscle regeneration has been an area of intense investigation over recent decades. The consensus is that a specialized self-renewing stem cell, termed the satellite cell, plays a major role during the process of regeneration in amniotes. How broadly this mechanism is deployed within the vertebrate phylogeny remains an open question. A lack of information on the role of cells analogous to the satellite cell in other vertebrate systems is even more unexpected given the fact that satellite cells were first designated in frogs. An intriguing aspect of this debate is that a number of amphibia and many fish species exhibit epimorphic regenerative processes in specific tissues, whereby regeneration occurs by the dedifferentiation of the damaged tissue, without deploying specialized stem cell populations analogous to satellite cells. Hence, it is feasible that a cellular process completely distinct from that deployed during mammalian muscle regeneration could operate in species capable of epimorphic regeneration. In this minireview, we examine the evidence for the broad phylogenetic distribution of satellite cells. We conclude that, in the vertebrates examined so far, epimorphosis does not appear to be deployed during muscle regeneration, and that analogous cells expressing similar marker genes to satellite cells appear to be deployed during the regenerative process. However, the functional definition of these cells as self-renewing muscle stem cells remains a final hurdle to the definition of the satellite cell as a generic vertebrate cell type.

  16. Sox2 promotes survival of satellite glial cells in vitro

    SciTech Connect

    Koike, Taro Wakabayashi, Taketoshi; Mori, Tetsuji; Hirahara, Yukie; Yamada, Hisao

    2015-08-14

    Sox2 is a transcriptional factor expressed in neural stem cells. It is known that Sox2 regulates cell differentiation, proliferation and survival of the neural stem cells. Our previous study showed that Sox2 is expressed in all satellite glial cells of the adult rat dorsal root ganglion. In this study, to examine the role of Sox2 in satellite glial cells, we establish a satellite glial cell-enriched culture system. Our culture method succeeded in harvesting satellite glial cells with the somata of neurons in the dorsal root ganglion. Using this culture system, Sox2 was downregulated by siRNA against Sox2. The knockdown of Sox2 downregulated ErbB2 and ErbB3 mRNA at 2 and 4 days after siRNA treatment. MAPK phosphorylation, downstream of ErbB, was also inhibited by Sox2 knockdown. Because ErbB2 and ErbB3 are receptors that support the survival of glial cells in the peripheral nervous system, apoptotic cells were also counted. TUNEL-positive cells increased at 5 days after siRNA treatment. These results suggest that Sox2 promotes satellite glial cell survival through the MAPK pathway via ErbB receptors. - Highlights: • We established satellite glial cell culture system. • Function of Sox2 in satellite glial cell was examined using siRNA. • Sox2 knockdown downregulated expression level of ErbB2 and ErbB3 mRNA. • Sox2 knockdown increased apoptotic satellite glial cell. • Sox2 promotes satellite glial cell survival through ErbB signaling.

  17. Frequency of M-cadherin-stained satellite cells declines in human muscles during aging.

    PubMed

    Sajko, Spela; Kubínová, Lucie; Cvetko, Erika; Kreft, Marko; Wernig, Anton; Erzen, Ida

    2004-02-01

    To answer the question of whether the satellite cell pool in human muscle is reduced during aging, we detected satellite cells in 30- microm-thick transverse sections under the confocal microscope by binding of M-cadherin antibody. The basal lamina was detected with laminin. Nuclei were stained with bisbenzimide or propidium iodide. Satellite cells were counted by applying the disector method and unbiased sampling design. To determine if there are age-related differences in muscle fiber types, morphometric characteristics of muscle fibers were examined on thin sections stained for myofibrillar ATPase. Autopsy samples of vastus lateralis muscle from six young (28.7 +/- 2.3 years) and six old (70.8 +/- 1.3 years) persons who had suffered sudden death were analyzed. Numbers of satellite cells per fiber length (Nsc/Lfib) and number of satellite cells per total number of nuclei (satellite cell nuclei + myonuclei) (Nsc/Nnucl) were significantly lower in the old group (p < 0.05). We demonstrate the importance of proper sampling and counting in estimation of sparsely distributed structures such as satellite cells. Our results support the hypothesis that the satellite cell fraction declines during aging.

  18. Acetylcholine receptor channels are present in undifferentiated satellite cells but not in embryonic myoblasts in culture.

    PubMed

    Cossu, G; Eusebi, F; Grassi, F; Wanke, E

    1987-09-01

    The expression and the physiological properties of acetylcholine receptors (AChRs) of mononucleated myogenic cells, isolated from either embryonic or adult muscle of the mouse, have been investigated using the gigaohm seal patch-clamp technique in combination with immunocytochemistry (with an anti-myosin antibody) and alpha-bungarotoxin binding techniques. Undifferentiated (myosin-negative) embryonic myoblasts, grown either in mass culture or under clonal conditions, were found to be unresponsive to ACh and did not bind alpha-bungarotoxin. On the contrary, undifferentiated satellite cells (from adult muscle) exhibited channels activated by ACh and alpha-bungarotoxin binding sites similar to those observed in differentiated (myosin-positive) embryonic myoblasts and myotubes. Two classes of ACh-activated channels with different opening frequencies were identified. The major class of channels had a conductance of about 42 pS and mean open time of 3.1-8.2 msec. The minor class of channels had smaller conductance (about 17 pS) and similar open time. During differentiation, the conductance of the two channels did not change significantly, while channel lifetime became shorter in myotubes derived from satellite cells but not in myotubes derived from embryonic myoblasts. The relative proportion of small over large channels was significantly larger in embryonic than in adult myogenic cells.

  19. Catalogue of satellite photography of the active volcanoes of the world

    NASA Technical Reports Server (NTRS)

    Heiken, G.

    1976-01-01

    A catalogue is presented of active volcanoes as viewed from Earth-orbiting satellites. The listing was prepared of photographs, which have been screened for quality, selected from the earth resources technology satellite (ERTS) and Skylab, Apollo and Gemini spacecraft. There is photography of nearly every active volcano in the world; the photographs are particularly useful for regional studies of volcanic fields.

  20. Skeletal muscle satellite cells: mediators of muscle growth during development and implications for developmental disorders.

    PubMed

    Dayanidhi, Sudarshan; Lieber, Richard L

    2014-11-01

    Satellite cells (SCs) are the muscle stem cells responsible for longitudinal and cross-sectional postnatal growth and repair after injury and which provide new myonuclei when needed. We review their morphology and contribution to development and their role in sarcomere and myonuclear addition. SCs, similar to other tissue stem cells, cycle through different states, such as quiescence, activation, and self-renewal, and thus we consider the signaling mechanisms involved in maintenance of these states. The role of the SC niche and their interactions with other cells, such as fibroblasts and the extracellular matrix, are all emerging as major factors that affect aging and disease. Interestingly, children with cerebral palsy appear to have a reduced SC number, which could play a role in their reduced muscular development and even in muscular contracture formation. Finally, we review the current information on SC dysfunction in children with muscular dystrophy and emerging therapies that target promotion of myogenesis and reduction of fibrosis.

  1. Position surveillance using one active ranging satellite and time-of-arrival of a signal from an independent satellite

    NASA Technical Reports Server (NTRS)

    Anderson, R. E.; Frey, R. L.; Lewis, J. R.

    1980-01-01

    Position surveillance using one active ranging/communication satellite and the time-of-arrival of signals from an independent satellite was shown to be feasible and practical. A towboat on the Mississippi River was equipped with a tone-code ranging transponder and a receiver tuned to the timing signals of the GOES satellite. A similar transponder was located at the office of the towing company. Tone-code ranging interrogations were transmitted from the General Electric Earth Station Laboratory through ATS-6 to the towboat and to the ground truth transponder office. Their automatic responses included digital transmissions of time-of-arrival measurements derived from the GOES signals. The Earth Station Laboratory determined ranges from the satellites to the towboat and computed position fixes. The ATS-6 lines-of-position were more precise than 0.1 NMi, 1 sigma, and the GOES lines-of-position were more precise than 1.6 NMi, 1 sigma. High quality voice communications were accomplished with the transponders using a nondirectional antenna on the towboat. The simple and effective surveillance technique merits further evaluation using operational maritime satellites.

  2. Detection of Rift Valley fever viral activity in Kenya by satellite remote sensing imagery

    NASA Technical Reports Server (NTRS)

    Linthicum, Kenneth J.; Bailey, Charles L.; Davies, F. Glyn; Tucker, Compton J.

    1987-01-01

    Data from the advanced very high resolution radiometer on board the National Oceanic and Atmospheric Administration's polar-orbiting meteorological satellites have been used to infer ecological parameters associated with Rift Valley fever (RVF) viral activity in Kenya. An indicator of potential viral activity was produced from satellite data for two different ecological regions in Kenya, where RVF is enzootic. The correlation between the satellite-derived green vegetation index and the ecological parameters associated with RVF virus suggested that satellite data may become a forecasting tool for RVF in Kenya and, perhaps, in other areas of sub-Saharan Africa.

  3. Pax7-expressing satellite cells are indispensable for adult skeletal muscle regeneration.

    PubMed

    Sambasivan, Ramkumar; Yao, Roseline; Kissenpfennig, Adrien; Van Wittenberghe, Laetitia; Paldi, Andràs; Gayraud-Morel, Barbara; Guenou, Hind; Malissen, Bernard; Tajbakhsh, Shahragim; Galy, Anne

    2011-09-01

    Distinct cell populations with regenerative capacity have been reported to contribute to myofibres after skeletal muscle injury, including non-satellite cells as well as myogenic satellite cells. However, the relative contribution of these distinct cell types to skeletal muscle repair and homeostasis and the identity of adult muscle stem cells remain unknown. We generated a model for the conditional depletion of satellite cells by expressing a human diphtheria toxin receptor under control of the murine Pax7 locus. Intramuscular injection of diphtheria toxin during muscle homeostasis, or combined with muscle injury caused by myotoxins or exercise, led to a marked loss of muscle tissue and failure to regenerate skeletal muscle. Moreover, the muscle tissue became infiltrated by inflammatory cells and adipocytes. This localised loss of satellite cells was not compensated for endogenously by other cell types, but muscle regeneration was rescued after transplantation of adult Pax7(+) satellite cells alone. These findings indicate that other cell types with regenerative potential depend on the presence of the satellite cell population, and these observations have important implications for myopathic conditions and stem cell-based therapeutic approaches.

  4. Satellite-like cells contribute to pax7-dependent skeletal muscle repair in adult zebrafish.

    PubMed

    Berberoglu, Michael A; Gallagher, Thomas L; Morrow, Zachary T; Talbot, Jared C; Hromowyk, Kimberly J; Tenente, Inês M; Langenau, David M; Amacher, Sharon L

    2017-04-15

    Satellite cells, also known as muscle stem cells, are responsible for skeletal muscle growth and repair in mammals. Pax7 and Pax3 transcription factors are established satellite cell markers required for muscle development and regeneration, and there is great interest in identifying additional factors that regulate satellite cell proliferation, differentiation, and/or skeletal muscle regeneration. Due to the powerful regenerative capacity of many zebrafish tissues, even in adults, we are exploring the regenerative potential of adult zebrafish skeletal muscle. Here, we show that adult zebrafish skeletal muscle contains cells similar to mammalian satellite cells. Adult zebrafish satellite-like cells have dense heterochromatin, express Pax7 and Pax3, proliferate in response to injury, and show peak myogenic responses 4-5 days post-injury (dpi). Furthermore, using a pax7a-driven GFP reporter, we present evidence implicating satellite-like cells as a possible source of new muscle. In lieu of central nucleation, which distinguishes regenerating myofibers in mammals, we describe several characteristics that robustly identify newly-forming myofibers from surrounding fibers in injured adult zebrafish muscle. These characteristics include partially overlapping expression in satellite-like cells and regenerating myofibers of two RNA-binding proteins Rbfox2 and Rbfoxl1, known to regulate embryonic muscle development and function. Finally, by analyzing pax7a; pax7b double mutant zebrafish, we show that Pax7 is required for adult skeletal muscle repair, as it is in the mouse.

  5. Comparison and analysis of Wuding and avian chicken skeletal muscle satellite cells.

    PubMed

    Tong, H Q; Jiang, Z Q; Dou, T F; Li, Q H; Xu, Z Q; Liu, L X; Gu, D H; Rong, H; Huang, Y; Chen, X B; Jois, M; Te Pas, M F W; Ge, C R; Jia, J J

    2016-10-05

    Chicken skeletal muscle satellite cells are located between the basement membrane and the sarcolemma of mature muscle fibers. Avian broilers have been genetically selected based on their high growth velocity and large muscle mass. The Wuding chicken is a famous local chicken in Yunnan Province that undergoes non-selection breeding and is slow growing. In this study, we aimed to explore differences in the proliferation and differentiation properties of satellite cells isolated from the two chicken breeds. Using immunofluorescence, hematoxylin-eosin staining and real-time polymerase chain reaction analysis, we analyzed the in vitro characteristics of proliferating and differentiating satellite cells isolated from the two chicken breeds. The growth curve of satellite cells was S-shaped, and cells from Wuding chickens entered the logarithmic phase and plateau phase 1 day later than those from Avian chicken. The results also showed that the two skeletal muscle satellite cell lines were positive for Pax7, MyoD and IGF-1. The expression of Pax7 followed a downward trend, whereas that of MyoD and IGF-1 first increased and subsequently decreased in cells isolated from the two chickens. These data indicated that the skeletal muscle satellite cells of Avian chicken grow and differentiate faster than did those of Wuding chickens. We suggest that the methods of breeding selection applied to these breeds regulate the characteristics of skeletal muscle satellite cells to influence muscle growth.

  6. Space satellite power system. [conversion of solar energy by photovoltaic solar cell arrays

    NASA Technical Reports Server (NTRS)

    Glaser, P. E.

    1974-01-01

    The concept of a satellite solar power station was studied. It is shown that it offers the potential to meet a significant portion of future energy needs, is pollution free, and is sparing of irreplaceable earth resources. Solar energy is converted by photovoltaic solar cell arrays to dc energy which in turn is converted into microwave energy in a large active phased array. The microwave energy is beamed to earth with little attenuation and is converted back to dc energy on the earth. Economic factors are considered.

  7. T cell activation.

    PubMed

    Smith-Garvin, Jennifer E; Koretzky, Gary A; Jordan, Martha S

    2009-01-01

    This year marks the 25th anniversary of the first Annual Review of Immunology article to describe features of the T cell antigen receptor (TCR). In celebration of this anniversary, we begin with a brief introduction outlining the chronology of the earliest studies that established the basic paradigm for how the engaged TCR transduces its signals. This review continues with a description of the current state of our understanding of TCR signaling, as well as a summary of recent findings examining other key aspects of T cell activation, including cross talk between the TCR and integrins, the role of costimulatory molecules, and how signals may negatively regulate T cell function.Acronyms and DefinitionsAdapter protein: cellular protein that functions to bridge molecular interactions via characteristic domains able to mediate protein/protein or protein/lipid interactions Costimulation: signals delivered to T cells by cell surface receptors other than the TCR itself that potentiate T cell activation cSMAC: central supramolecular activation cluster Immunoreceptor tyrosine-based activation motif (ITAM): a short peptide sequence in the cytoplasmic tails of key surface receptors on hematopoietic cells that is characterized by tyrosine residues that are phosphorylated by Src family PTKs, enabling the ITAM to recruit activated Syk family kinases Inside-out signaling: signals initiated by engagement of immunoreceptors that lead to conformational changes and clustering of integrins, thereby increasing the affinity and avidity of the integrins for their ligands NFAT: nuclear factor of activated T cells PI3K: phosphoinositide 3-kinase PKC: protein kinase C PLC: phospholipase C pMHC: peptide major histocompatibility complex (MHC) complex pSMAC: peripheral supramolecular activation cluster PTK: protein tyrosine kinase Signal transduction: biochemical events linking surface receptor engagement to cellular responses TCR: T cell antigen receptor

  8. Phenotypic changes in satellite glial cells in cultured trigeminal ganglia.

    PubMed

    Belzer, Vitali; Shraer, Nathanael; Hanani, Menachem

    2010-11-01

    Satellite glial cells (SGCs) are specialized cells that form a tight sheath around neurons in sensory ganglia. In recent years, there is increasing interest in SGCs and they have been studied in both intact ganglia and in tissue culture. Here we studied phenotypic changes in SGCs in cultured trigeminal ganglia from adult mice, containing both neurons and SGCs, using phase optics, immunohistochemistry and time-lapse photography. Cultures were followed for up to 14 days. After isolation virtually every sensory neuron is ensheathed by SGCs, as in the intact ganglia. After one day in culture, SGCs begin to migrate away from their parent neurons, but in most cases the neurons still retain an intact glial cover. At later times in culture, there is a massive migration of SGCs away from the neurons and they undergo clear morphological changes, and at 7 days they become spindle-shaped. At one day in culture SGCs express the glial marker glutamine synthetase, and also the purinergic receptor P2X7. From day 2 in culture the glutamine synthetase expression is greatly diminished, whereas that of P2X7 is largely unchanged. We conclude that SGCs retain most of their characteristics for about 24 h after culturing, but undergo major phenotypic changes at later times.

  9. Androgen receptor expression in satellite cells of the neonatal levator ani of the rat.

    PubMed

    Swift-Gallant, Ashlyn; Monks, D Ashley

    2013-06-01

    Androgens are thought to mediate sexual differentiation of spinal nucleus of the bulbocavernosus (SNB) motoneurons via actions on androgen receptors (ARs) within their target muscles bulbocavernosus and levator ani (LA). However, the cells within these muscles which mediate masculinization of the SNB remain undefined. Until recently, myocytes were thought to be the most likely candidate cell type. However, genetic tests of AR function in myocytes have failed to support a sufficient role for these cells in producing masculine SNB morphology, suggesting the involvement of other cell types. To identify other candidate cell types in the LA, we evaluated whether satellite cells or fibroblasts express AR. Fluorescent immunohistochemistry and confocal microscopy were used to evaluate whether satellite cells and fibroblasts express AR in neonatal male and female rats in the LA and an adjacent sexually monomorphic control muscle (CM). We found that a small proportion of satellite cells in the LA express AR and that this proportion is significantly greater in the LA compared to the CM. No sex differences were found between the proportions of satellite cells expressing AR in either muscle. Less colocalization of satellite cells and AR was seen in postnatal day 3 muscle than in postnatal day 1 muscle. In contrast, only negligible amounts of fibroblasts labeled with S100A4 express AR in either the LA or the CM. Together, findings support satellite cells, but not fibroblasts, as a candidate cell type involved in the sexual differentiation of the SNB neuromuscular system.

  10. Activities and future plan of earth observation by satellites

    NASA Astrophysics Data System (ADS)

    Hakura, Yukio

    1980-09-01

    The Earth Observation Center of NASDA has been receiving MSS (multispectral scanner) and RBV (return beam vidicon) data from NASAs Landsat satellites since January 1979. The data are widely used for research and applications by government institutions, universities, industries, etc. The first of Japanese Earth observation satellite series, MOS-1 (Marine Observation Satellite-1) which carries MESSR (visible and near-IR radiometer of push-broom scanning type), VTIR (visible and thermal IR radiometer), and MSR (microwave scanning radiometer), is under development with target date of its launch in 1984 FY.

  11. Transcription of Satellite III non-coding RNAs is a general stress response in human cells

    PubMed Central

    Valgardsdottir, Rut; Chiodi, Ilaria; Giordano, Manuela; Rossi, Antonio; Bazzini, Silvia; Ghigna, Claudia; Riva, Silvano; Biamonti, Giuseppe

    2008-01-01

    In heat-shocked human cells, heat shock factor 1 activates transcription of tandem arrays of repetitive Satellite III (SatIII) DNA in pericentromeric heterochromatin. Satellite III RNAs remain associated with sites of transcription in nuclear stress bodies (nSBs). Here we use real-time RT-PCR to study the expression of these genomic regions. Transcription is highly asymmetrical and most of the transcripts contain the G-rich strand of the repeat. A low level of G-rich RNAs is detectable in unstressed cells and a 104-fold induction occurs after heat shock. G-rich RNAs are induced by a wide range of stress treatments including heavy metals, UV-C, oxidative and hyper-osmotic stress. Differences exist among stressing agents both for the kinetics and the extent of induction (>100- to 80.000-fold). In all cases, G-rich transcripts are associated with nSBs. On the contrary, C-rich transcripts are almost undetectable in unstressed cells and modestly increase after stress. Production of SatIII RNAs after hyper-osmotic stress depends on the Tonicity Element Binding Protein indicating that activation of the arrays is triggered by different transcription factors. This is the first example of a non-coding RNA whose transcription is controlled by different transcription factors under different growth conditions. PMID:18039709

  12. [The influence of satellite cells on meat quality and its differential regulation].

    PubMed

    Shen, Lin-Yuan; Zhang, Shun-Hua; Wu, Ze-Hui; Zheng, Meng-Yue; Li, Xue-Wei; Zhu, Li

    2013-09-01

    Satellite cell is a kind of myogenic stem cells, which plays an important role in muscle development and injury repair. Through proliferation, differentiation and fusion of muscle fiber can satellite cells make new myonuclear, leading to the hypertrophy of skeletal muscle and fiber type transformation, and this would further affect the meat quality. Here, we review the relationship between muscle fiber development and meat quality attributes as well as the influence of the satellite cell differentiation on muscle fiber character. Besides, we also summarize the classical signaling pathway (i.e., Notch etc.) and influence of epigenetic regulation (i.e. miRNA) on muscle quality.

  13. The effect of temperature on proliferation and differentiation of chicken skeletal muscle satellite cells isolated from different muscle types.

    PubMed

    Harding, Rachel L; Halevy, Orna; Yahav, Shlomo; Velleman, Sandra G

    2016-04-01

    Skeletal muscle satellite cells are a muscle stem cell population that mediate posthatch muscle growth and repair. Satellite cells respond differentially to environmental stimuli based upon their fiber-type of origin. The objective of this study was to determine how temperatures below and above the in vitro control of 38°C affected the proliferation and differentiation of satellite cells isolated from the chicken anaerobic pectoralis major (p. major) or mixed fiber biceps femoris (b.femoris) muscles. The satellite cells isolated from the p. major muscle were more sensitive to both cold and hot temperatures compared to the b.femoris satellite cells during both proliferation and differentiation. The expressions of myogenic regulatory transcription factors were also different between satellite cells from different fiber types. MyoD expression, which partially regulates proliferation, was generally expressed at higher levels in p. major satellite cells compared to the b.femoris satellite cells from 33 to 43°C during proliferation and differentiation. Similarly, myogenin expression, which is required for differentiation, was also expressed at higher levels in p. major satellite cells in response to both cold and hot temperatures during proliferation and differentiation than b. femoris satellite cells. These data demonstrate that satellite cells from the anaerobic p. major muscle are more sensitive than satellite cells from the aerobic b. femoris muscle to both hot and cold thermal stress during myogenic proliferation and differentiation.

  14. Satellite Cells CD44 Positive Drive Muscle Regeneration in Osteoarthritis Patients.

    PubMed

    Scimeca, Manuel; Bonanno, Elena; Piccirilli, Eleonora; Baldi, Jacopo; Mauriello, Alessandro; Orlandi, Augusto; Tancredi, Virginia; Gasbarra, Elena; Tarantino, Umberto

    2015-01-01

    Age-related bone diseases, such as osteoarthritis and osteoporosis, are strongly associated with sarcopenia and muscle fiber atrophy. In this study, we analyzed muscle biopsies in order to demonstrate that, in osteoarthritis patients, both osteophytes formation and regenerative properties of muscle stem cells are related to the same factors. In particular, thanks to immunohistochemistry, transmission electron microscopy, and immunogold labeling we investigated the role of BMP-2 in muscle stem cells activity. In patients with osteoarthritis both immunohistochemistry and transmission electron microscopy allowed us to note a higher number of CD44 positive satellite muscle cells forming syncytium. Moreover, the perinuclear and cytoplasmic expression of BMP-2 assessed by in situ molecular characterization of satellite cells syncytia suggest a very strict correlation between BMP-2 expression and muscle regeneration capability. Summing up, the higher BMP-2 expression in osteoarthritic patients could explain the increased bone mineral density as well as decreased muscle atrophy in osteoarthrosic patients. In conclusion, our results suggest that the control of physiological BMP-2 balance between bone and muscle tissues may be considered as a potential pharmacological target in bone-muscle related pathology.

  15. Satellite glial cell responses to neuronal firing in the nervous system of Helix pomatia.

    PubMed

    Gommerat, I; Gola, M

    1994-03-01

    Patch clamp experiments were conducted on satellite glial cells attached to the cell body of neurons in place within the nervous system of the snail Helix pomatia. The glial cells were studied using cell-attached and whole-cell patch clamp configurations while the underlying neurons were under current or voltage clamp control. The resting potential of the glial cells (-69 mV) was more negative than that of the underlying neurons (-53 mV), due to their high K+ selectivity. Densely packed K+ channels were present, some of which were active at the cell resting potential. Neuronal firing elicited a cumulative depolarization of the glial cells. Large K+ currents flowing from V-clamped neurons depolarized the glial layer by up to 30 mV. The glial depolarization was directly correlated with the size of the neuronal K+ current. The glial cells recovered their resting potential within 2-5 sec. The neuronal depolarization induced a delayed (20-30 sec) and persistent (3-4 min) increase in the glial K+ channel opening probability. Likewise, pulses of K+ (20-50 mM)-rich saline activated the glial channels, unless the underlying neuron was held hyperpolarized. In low Ca(2+)-high Mg2+ saline, neuron depolarization and K(+)-rich saline did not activate the glial K+ channels. These data indicate that a calcium-dependent signal released from the neuronal cell body was involved in glial channel regulation. Neuron-induced channel opening may help eliminate the K+ ions flowing from active neurons.

  16. Raman activated cell sorting.

    PubMed

    Song, Yizhi; Yin, Huabing; Huang, Wei E

    2016-08-01

    Single cell Raman spectra (SCRS) are intrinsic biochemical profiles and 'chemical images' of single cells which can be used to characterise phenotypic changes, physiological states and functions of cells. On the base of SCRS, Raman activated cell sorting (RACS) provides a label-free cell sorting approach, which can link single cells to their chemical or phenotypic profiles. Overcoming naturally weak Raman signals, establishing Raman biomarker as sorting criteria to RACS and improving specific sorting technology are three challenges of developing RACS. Advances on Raman spectroscopy such as stimulated Raman scattering (SRS) and pre-screening helped to increase RACS sorting speed. Entire SCRS can be characterised using pattern recognition methods, and specific Raman bands can be extracted as biomarkers for RACS. Recent advances on cell sorting technologies based on microfluidic device and surface-ejection enable accurate and reliable single cell sorting from complex samples. A high throughput RACS will be achievable in near future by integrating fast Raman detection system such as SRS with microfluidic RACS and Raman activated cell ejection (RACE).

  17. The effects of growth hormone on avian skeletal muscle satellite cell proliferation and differentiation.

    PubMed

    Halevy, O; Hodik, V; Mett, A

    1996-01-01

    Growth hormone receptor (GH-R) mRNA was expressed in avian skeletal muscle tissue and satellite cells in culture, and was capable of binding chicken growth hormone (cGH). In the satellite cells, GH-R gene expression was regulated by cGH in a biphasic manner which correlated with the GH effect on cell proliferation: 2-10 ng/ml of the hormone increased GH-R mRNA and DNA synthesis, whereas higher concentrations attenuated these effects. GH induced insulin-like growth factor I (IGF-I) mRNA, a potential factor for satellite cell proliferation and differentiation. However, GH inhibited the gene expression of myogenin and the expression of muscle-specific proteins in a dose-dependent manner. These results suggest a role of GH for inhibiting satellite cell differentiation in an IGF-I-independent manner. During satellite cell differentiation, both GH-R mRNA expression and cGH binding peaked when cells were still proliferating and beginning to fuse, and then declined as cells fully differentiated. GH-R mRNA expression in muscle tissue and the satellite cell fraction was evaluated during chicken growth. In both fractions, GH-R mRNA peaked at 4 days of age and then declined in correlation with the reduction of muscle regulatory gene expression. Our results are in contrast with previous studies on rat muscle satellite cells, suggesting a difference between mammalian and avian species in the mode of action of GH in these cells. Our notion is that GH, via its own receptor, promotes more satellite cells to proliferate by inhibiting their differentiation, leading to the addition of more nuclei to the growing muscle.

  18. MicroRNA-128 regulates the proliferation and differentiation of bovine skeletal muscle satellite cells by repressing Sp1.

    PubMed

    Dai, Yang; Zhang, Wei Ran; Wang, Yi Min; Liu, Xin Feng; Li, Xin; Ding, Xiang Bin; Guo, Hong

    2016-03-01

    MicroRNAs (miRNAs) play essential roles in muscle cell proliferation and differentiation. The muscle-specific miRNAs miR-1 and miR-206 have been shown to regulate muscle development and promote myogenic differentiation; however, it is likely that a number of other miRNAs play important roles in regulating myogenesis as well. microRNA-128 (miR-128) has been reported to be highly expressed in brain and skeletal muscle, and we found that miR-128 is also up-regulated during bovine skeletal muscle satellite cell differentiation using microarray analysis and qRT-PCR. However, little is known about the functions of miR-128 in bovine skeletal muscle satellite cell development. In this study, we investigated the biological functions of miR-128 in bovine skeletal muscle cell development. Using a dual-luciferase reporter assay, we confirmed that miR-128 regulates the Sp1 gene. Over-expression of miR-128 reduced Sp1 protein levels and inhibited muscle satellite cell proliferation and differentiation. Inhibition of miR-128 increased Sp1 protein levels and promoted muscle satellite cell differentiation but also suppressed proliferation. Changes in miR-128 and Sp1 expression levels also affected the protein levels of MyoD and CDKN1A. Sp1, an activator of MyoD and a suppressor of CDKN1A, plays an important role in bovine muscle cell proliferation and differentiation. The results of our study reveal a mechanism by which miR-128 regulates bovine skeletal muscle satellite cell proliferation and myogenic differentiation via Sp1.

  19. COUP-TFII regulates satellite cell function and muscular dystrophy

    PubMed Central

    Xie, Xin; Tsai, Sophia Y.

    2016-01-01

    Duchenne muscular dystrophy (DMD) is a severe and progressive muscle-wasting disease caused by mutations in the dystrophin gene. Although dystrophin deficiency in myofiber triggers the disease’s pathological changes, the degree of satellite cell (SC) dysfunction defines disease progression. Here, we have identified chicken ovalbumin upstream promoter–transcription factor II (COUP-TFII) hyperactivity as a contributing factor underlying muscular dystrophy in a dystrophin-deficient murine model of DMD. Ectopic expression of COUP-TFII in murine SCs led to Duchenne-like dystrophy in the muscles of control animals and exacerbated degenerative myopathies in dystrophin-deficient mice. COUP-TFII–overexpressing mice exhibited regenerative failure that was attributed to deficient SC proliferation and myoblast fusion. Mechanistically, we determined that COUP-TFII coordinated a regenerative program through combined regulation of multiple promyogenic factors. Furthermore, inhibition of COUP-TFII preserved SC function and counteracted the muscle weakness associated with Duchenne-like dystrophy in the murine model, suggesting that targeting COUP-TFII is a potential treatment for DMD. Together, our findings reveal a regulatory role of COUP-TFII in the development of muscular dystrophy and open up a potential therapeutic opportunity for managing disease progression in patients with DMD. PMID:27617862

  20. Expression of Transthyretin during bovine myogenic satellite cell differentiation.

    PubMed

    Pokharel, Smritee; Kamli, Majid Rasool; Mir, Bilal Ahmad; Malik, Adeel; Lee, Eun Ju; Choi, Inho

    2014-09-01

    Adult myogenesis responsible for the maintenance and repair of muscle tissue is mainly under the control of myogenic regulatory factors (MRFs) and a few other genes. Transthyretin gene (TTR), codes for a carrier protein for thyroxin (T4) and retinol binding protein bound with retinol in blood plasma, plays a critical role during the early stages of myogenesis. Herein, we investigated the relationship of TTR with other muscle-specific genes and report their expression in muscle satellite cells (MSCs), and increased messenger RNA (mRNA) and protein expression of TTR during MSCs differentiation. Silencing of TTR resulted in decreased myotube formation and decreased expression of myosin light chain (MYL2), myosin heavy chain 3 (MYH3), matrix gla protein (MGP), and voltage-dependent L type calcium channel (Cav1.1) genes. Increased mRNA expression observed in TTR and other myogenic genes with the addition of T4 decreased significantly following TTR knockdown, indicating the critical role of TTR in T4 transportation. Similarly, decreased expression of MGP and Cav1.1 following TTR knockdown signifies the dual role of TTR in controlling muscle myogenesis via regulation of T4 and calcium channel. Our computational and experimental evidences indicate that TTR has a relationship with MRFs and may act on calcium channel and related genes.

  1. Satellited 4q identified in amniotic fluid cells

    SciTech Connect

    Miller, I.; Hsieh, C.L.; Songster, G.

    1995-01-16

    Extra material was identified on the distal long arm of a chromosome 4 in an amniotic fluid specimen sampled at 16.6 weeks of gestational age. There was no visible loss of material from chromosome 4, and no evidence for a balanced rearrangement. The primary counseling issue in this case was advanced maternal age. Ultrasound findings were normal, and family history was unremarkable. The identical 4qs chromosome was observed in cells from a paternal peripheral blood specimen and appeared to be an unbalanced rearrangement. This extra material was NOR positive in lymphocytes from the father, but was negative in the fetal amniocytes. Father`s relatives were studied to verify the familial origin of this anomaly. In situ hybridization with both exon and intron sequences of ribosomal DNA demonstrated that ribosomal DNA is present at the terminus of the 4qs chromosome in the fetus, father, and paternal grandmother. This satellited 4q might have been derived from a translocation event that resulted in very little or no loss from the 4q and no specific phenotype. This derivative chromosome 4 has been inherited through at least 3 generations of phenotypically normal individuals. 8 refs., 3 figs.

  2. Flow Cytometry and Transplantation-Based Quantitative Assays for Satellite Cell Self-Renewal and Differentiation.

    PubMed

    Arpke, Robert W; Kyba, Michael

    2016-01-01

    In response to muscle damage, satellite cells proliferate and undertake both differentiation and self-renewal, generating new functional muscle tissue and repopulating this new muscle with stem cells for future injury responses. For many questions relating to the physiological regulation of satellite cells, quantitative readouts of self-renewal and differentiation can be very useful. There is a particular need for a quantitative assay for satellite cell self-renewal that does not rely solely upon sectioning, staining and counting cells in sections. In this chapter, we provide detailed methods for quantifying the self-renewal and differentiation potential of a given population of satellite cells using an assay involving transplantation into injured, regenerating muscle together with specific markers for donor cell identity and state of differentiation. In particular, using the Pax7-ZsGreen transgene as a marker of satellite cell state, self-renewal can be quantified by FACS on transplanted muscle to actually count the total number of resident satellite cells at time points following transplantation.

  3. [Transdisciplinary Approach for Sarcopenia. The effects of exercise on skeletal muscle hypertrophy and satellite cells].

    PubMed

    Fujimaki, Shin; Takemasa, Tohru; Kuwabara, Tomoko

    2014-10-01

    Skeletal muscle has a high degree of plasticity. The mass of skeletal muscle maintains owing to muscle protein synthesis and the regeneration by satellite cells. Skeletal muscle atrophy with aging (sarcopenia) is developed by decline of muscle protein synthesis and dysfunction of satellite cells. It is urgently necessary for today's highly aged society to elucidate the mechanism of sarcopenia and to establish prevention measure. This review shows that the positive effects of "exercise" on muscle protein synthesis and satellite cell function including their main molecular mechanism.

  4. Theoretical Investigation of Laser-Radiation Effects on Satellite Solar Cells

    NASA Astrophysics Data System (ADS)

    Abdel-Hadi, Yasser; El-Hameed, Afaf; Hamdy, Ola

    This research concerns with the studying of laser-powered solar panels for space applications. A model describing the laser effects on satellite solar cell has been developed. These effects are studied theoretically in order to determine the performance limits of the solar cells when they are powered by laser radiation during the satellite eclipse. A comparison between some different common types of the solar cells used for these purpose is considered in this study. The obtained results are reported to optimize the use of laser-powered satellites.

  5. Isolation and Characterization of Satellite Cells from Rat Head Branchiomeric Muscles

    PubMed Central

    Carvajal Monroy, Paola L.; Yablonka-Reuveni, Zipora; Grefte, Sander; Kuijpers-Jagtman, Anne Marie; Wagener, Frank A.D.T.G.; Von den Hoff, Johannes W.

    2015-01-01

    Fibrosis and defective muscle regeneration can hamper the functional recovery of the soft palate muscles after cleft palate repair. This causes persistent problems in speech, swallowing, and sucking. In vitro culture systems that allow the study of satellite cells (myogenic stem cells) from head muscles are crucial to develop new therapies based on tissue engineering to promote muscle regeneration after surgery. These systems will offer new perspectives for the treatment of cleft palate patients. A protocol for the isolation, culture and differentiation of satellite cells from head muscles is presented. The isolation is based on enzymatic digestion and trituration to release the satellite cells. In addition, this protocol comprises an innovative method using extracellular matrix gel coatings of millimeter size, which requires only low numbers of satellite cells for differentiation assays. PMID:26274878

  6. Pharyngeal Satellite Cells Undergo Myogenesis Under Basal Conditions and Are Required for Pharyngeal Muscle Maintenance.

    PubMed

    Randolph, Matthew E; Phillips, Brittany L; Choo, Hyo-Jung; Vest, Katherine E; Vera, Yandery; Pavlath, Grace K

    2015-12-01

    The pharyngeal muscles of the nasal, oral, and laryngeal pharynxes are required for swallowing. Pharyngeal muscles are preferentially affected in some muscular dystrophies yet spared in others. Muscle stem cells, called satellite cells, may be critical factors in the development of pharyngeal muscle disorders; however, very little is known about pharyngeal satellite cells (PSC) and their role in pharyngeal muscles. We show that PSC are distinct from the commonly studied hindlimb satellite cells both transcriptionally and biologically. Under basal conditions PSC proliferate, progress through myogenesis, and fuse with pharyngeal myofibers. Furthermore, PSC exhibit biologic differences dependent on anatomic location in the pharynx. Importantly, PSC are required to maintain myofiber size and myonuclear number in pharyngeal myofibers. Together, these results demonstrate that PSC are critical for pharyngeal muscle maintenance and suggest that satellite cell impairment could contribute to pharyngeal muscle pathology associated with various muscular dystrophies and aging.

  7. Isolation and Characterization of Satellite Cells from Rat Head Branchiomeric Muscles.

    PubMed

    Carvajal Monroy, Paola L; Yablonka-Reuveni, Zipora; Grefte, Sander; Kuijpers-Jagtman, Anne Marie; Wagener, Frank A D T G; Von den Hoff, Johannes W

    2015-07-20

    Fibrosis and defective muscle regeneration can hamper the functional recovery of the soft palate muscles after cleft palate repair. This causes persistent problems in speech, swallowing, and sucking. In vitro culture systems that allow the study of satellite cells (myogenic stem cells) from head muscles are crucial to develop new therapies based on tissue engineering to promote muscle regeneration after surgery. These systems will offer new perspectives for the treatment of cleft palate patients. A protocol for the isolation, culture and differentiation of satellite cells from head muscles is presented. The isolation is based on enzymatic digestion and trituration to release the satellite cells. In addition, this protocol comprises an innovative method using extracellular matrix gel coatings of millimeter size, which requires only low numbers of satellite cells for differentiation assays.

  8. Molecular and functional heterogeneity of early postnatal porcine satellite cell populations is associated with bioenergetic profile

    PubMed Central

    Miersch, Claudia; Stange, Katja; Hering, Silvio; Kolisek, Martin; Viergutz, Torsten; Röntgen, Monika

    2017-01-01

    During postnatal development, hyperplastic and hypertrophic processes of skeletal muscle growth depend on the activation, proliferation, differentiation, and fusion of satellite cells (SC). Therefore, molecular and functional SC heterogeneity is an important component of muscle plasticity and will greatly affect long-term growth performance and muscle health. However, its regulation by cell intrinsic and extrinsic factors is far from clear. In particular, there is only minor information on the early postnatal period which is critical for muscle maturation and the establishment of adult SC pools. Here, we separated two SC subpopulations (P40/50, P50/70) from muscle of 4-day-old piglets. Our results characterize P40/50 as homogeneous population of committed (high expression of Myf5), fast-proliferating muscle progenitors. P50/70 constituted a slow-proliferating phenotype and contains high numbers of differentiated SC progeny. During culture, P50/70 is transformed to a population with lower differentiation potential that contains 40% Pax7-positive cells. A reversible state of low mitochondrial activity that results from active down-regulation of ATP-synthase is associated with the transition of some of the P50/70 cells to this more primitive fate typical for a reserve cell population. We assume that P40/50 and P50/70 subpopulations contribute unequally in the processes of myofiber growth and maintenance of the SC pool. PMID:28344332

  9. Molecular and functional heterogeneity of early postnatal porcine satellite cell populations is associated with bioenergetic profile.

    PubMed

    Miersch, Claudia; Stange, Katja; Hering, Silvio; Kolisek, Martin; Viergutz, Torsten; Röntgen, Monika

    2017-03-27

    During postnatal development, hyperplastic and hypertrophic processes of skeletal muscle growth depend on the activation, proliferation, differentiation, and fusion of satellite cells (SC). Therefore, molecular and functional SC heterogeneity is an important component of muscle plasticity and will greatly affect long-term growth performance and muscle health. However, its regulation by cell intrinsic and extrinsic factors is far from clear. In particular, there is only minor information on the early postnatal period which is critical for muscle maturation and the establishment of adult SC pools. Here, we separated two SC subpopulations (P40/50, P50/70) from muscle of 4-day-old piglets. Our results characterize P40/50 as homogeneous population of committed (high expression of Myf5), fast-proliferating muscle progenitors. P50/70 constituted a slow-proliferating phenotype and contains high numbers of differentiated SC progeny. During culture, P50/70 is transformed to a population with lower differentiation potential that contains 40% Pax7-positive cells. A reversible state of low mitochondrial activity that results from active down-regulation of ATP-synthase is associated with the transition of some of the P50/70 cells to this more primitive fate typical for a reserve cell population. We assume that P40/50 and P50/70 subpopulations contribute unequally in the processes of myofiber growth and maintenance of the SC pool.

  10. Mobile satellite communications technology - A summary of NASA activities

    NASA Technical Reports Server (NTRS)

    Dutzi, E. J.; Knouse, G. H.

    1986-01-01

    Studies in recent years indicate that future high-capacity mobile satellite systems are viable only if certain high-risk enabling technologies are developed. Accordingly, NASA has structured an advanced technology development program aimed at efficient utilization of orbit, spectrum, and power. Over the last two years, studies have concentrated on developing concepts and identifying cost drivers and other issues associated with the major technical areas of emphasis: vehicle antennas, speech compression, bandwidth-efficient digital modems, network architecture, mobile satellite channel characterization, and selected space segment technology. The program is now entering the next phase - breadboarding, development, and field experimentation.

  11. Autocrine and paracrine angiopoietin 1/Tie-2 signaling promotes muscle satellite cell self-renewal.

    PubMed

    Abou-Khalil, Rana; Le Grand, Fabien; Pallafacchina, Giorgia; Valable, Samuel; Authier, François-Jérôme; Rudnicki, Michael A; Gherardi, Romain K; Germain, Stéphane; Chretien, Fabrice; Sotiropoulos, Athanassia; Lafuste, Peggy; Montarras, Didier; Chazaud, Bénédicte

    2009-09-04

    Mechanisms governing muscle satellite cell withdrawal from cell cycle to enter into quiescence remain poorly understood. We studied the role of angiopoietin 1 (Ang1) and its receptor Tie-2 in the regulation of myogenic precursor cell (mpc) fate. In human and mouse, Tie-2 was preferentially expressed by quiescent satellite cells in vivo and reserve cells (RCs) in vitro. Ang1/Tie-2 signaling, through ERK1/2 pathway, decreased mpc proliferation and differentiation, increased the number of cells in G0, increased expression of RC-associated markers (p130, Pax7, Myf-5, M-cadherin), and downregulated expression of differentiation-associated markers. Silencing Tie-2 had opposite effects. Cells located in the satellite cell neighborhood (smooth muscle cells, fibroblasts) upregulated RC-associated markers by secreting Ang1 in vitro. In vivo, Tie-2 blockade and Ang1 overexpression increased the number of cycling and quiescent satellite cells, respectively. We propose that Ang1/Tie-2 signaling regulates mpc self-renewal by controlling the return to quiescence of a subset of satellite cells.

  12. Neonatal Satellite Cells Form Small Myotubes In Vitro.

    PubMed

    Carvajal Monroy, P L; Grefte, S; Kuijpers-Jagtman, A M; Von den Hoff, J W; Wagener, F A D T G

    2017-03-01

    Although palatal muscle reconstruction in patients with cleft palate takes place during early childhood, normal speech development is often not achieved. We hypothesized that the intrinsic properties of head satellite cells (SCs) and the young age of these patients contribute to the poor muscle regeneration after surgery. First, we studied the fiber type distribution and the expression of SC markers in ex vivo muscle tissue from head (branchiomeric) and limb (somite-derived) muscles from neonatal (2-wk-old) and young (9-wk-old) rats. Next, we cultured SCs isolated from these muscles for 5, 7, and 9 d, and investigated the in vitro expression of SC markers, as well as changes in proliferation, early differentiation, and fusion index (myotube formation) in these cells. In our ex vivo samples, we found that virtually all myofibers in both the masseter (Mass) and the levator veli palatini (LVP) muscles contained fast myosin heavy chain (MyHC), and a small percentage of digastric (Dig) and extensor digitorum longus myofibers also contained slow MyHC. This was independent of age. More SCs were found in muscles from neonatal rats as compared with young rats [17.6 (3.8%) v. 2.3 (1.6%); P < 0.0001]. In vitro, young branchiomeric head muscle (BrHM) SCs proliferated longer and differentiated later than limb muscle SCs. No differences were found between SC cultures from the different BrHMs. SC cultures from neonatal muscles showed a much higher proliferation index than those from young animals at 5 d (0.8 v. 0.2; P < 0.001). In contrast, the fusion index in neonate SCs was about twice as low as that in SCs from young muscles at 9 d [27.6 (1.4) v. 62.8 (10.2), P < 0.0001]. In conclusion, SCs from BrHM differ from limb muscles especially in their delayed differentiation. SCs from neonatal muscles form myotubes less efficiently than those from young muscles. These age-dependent differences in stem cell properties urge careful consideration for future clinical applications in

  13. A home away from home: challenges and opportunities in engineering in vitro muscle satellite cell niches

    PubMed Central

    Cosgrove, Benjamin D.; Sacco, Alessandra; Gilbert, Penney M.; Blau, Helen M.

    2009-01-01

    Satellite cells are skeletal muscle stem cells with a principal role in postnatal skeletal muscle regeneration. Satellite cells, like many tissue-specific adult stem cells, reside in a quiescent state in an instructive, anatomically defined niche. The satellite cell niche constitutes a distinct membrane-enclosed compartment within the muscle fiber, containing a diversity of biochemical and biophysical signals that influence satellite cell function. A major limitation to the study and clinical utility of satellite cells is that upon removal from the muscle fiber and plating in traditional plastic tissue culture platforms, their muscle stem cell properties are rapidly lost. Clearly, the maintenance of stem cell function is critically dependent on in vivo niche signals, highlighting the need to create novel in vitro microenvironments that allow for the maintenance and propagation of satellite cells while retaining their potential to function as muscle stem cells. Here, we discuss how emerging biomaterials technologies offer great promise for engineering in vitro microenvironments to meet these challenges. In engineered biomaterials, signaling molecules can be presented in a manner that more closely mimics cell-cell and cell-matrix interactions and matrices can be fabricated with diverse rigidities that approximate in vivo tissues. The development of in vitro microenvironments in which niche features can be systematically modulated will be instrumental not only to future insights into muscle stem cell biology and therapeutic approaches to muscle diseases and muscle wasting with aging, but also will provide a paradigm for the analysis of numerous adult tissue-specific stem cells. PMID:19751902

  14. The effect of in vivo and in vitro irradiation (25 Gy) on the subsequent in vitro growth of satellite cells

    NASA Technical Reports Server (NTRS)

    Mozdziak, P. E.; Schultz, E.; Cassens, R. G.

    1996-01-01

    The effect of in vivo and in vitro irradiation on subsequent satellite cell growth, in vitro, was investigated to ascertain the ability of a 25 Gy dose to inhibit satellite cell proliferation. Satellite cells were isolated from the left (irradiated) and right (non-irradiated) Pectoralis thoracicus of two-week-old tom turkeys 16 h (n=3) and seven weeks (n=2) after the left Pectoralis thoracicus had been irradiated (25 Gy). Satellite cells isolated from the irradiated and non-irradiated muscles exhibited similar (P>0.10) in vitro proliferation indicating that a population of satellite cells survived an in vivo dose of 25 Gy. In additional experiments, satellite cell cultures derived from tom turkey Pectoralis thoracicus were irradiated (25 Gy) in vitro. The number of satellite cells did not (P>0.05) increase in irradiated cultures for 134 h following irradiation, while satellite cells in non-irradiated cultures proliferated (P<0.05) over this time. At later time periods, satellite cell number increased (P<0.05) in irradiated cultures indicating that a population of satellite cells survived irradiation. The results of these in vitro experiments suggest that a 25 Gy dose of irradiation does not abolish satellite cell divisions in the turkey Pectoralis thoracicus.

  15. MicroRNA regulation of myogenic satellite cell proliferation and differentiation.

    PubMed

    Harding, Rachel L; Velleman, Sandra G

    2016-01-01

    Myogenic satellite cells are stem cells responsible for muscle growth and regeneration. MicroRNAs (miRNAs) play significant roles in regulating numerous cellular processes. Two genes essential to satellite cell function are syndecan-4 and glypican-1. To determine if miRNAs influence myogenic satellite cell function, one miRNA predicted to bind syndecan-4 (miR-128) and two predicted to bind glypican-1 (miR-24 and miR-16) were inhibited in vitro by transfection of inhibitors targeting each miRNA. Inhibition of these miRNAs differentially affected the expression of syndecan-4, glypican-1, and myogenic regulatory factors myoD and myogenin. Inhibition of miR-16 reduced proliferation of satellite cells at 72 h. Inhibition of miR-128 and miR-24 did not affect proliferation. Inhibition of miRNAs reduced differentiation of satellite cells into myotubes at 48 and 72 h except for miR-16, which only affected differentiation at 72 h. Inhibition of all three miRNAs decreased myotube width at 24 h of differentiation and increased myotube width at 48 h of differentiation. Inhibiting these miRNAs also increased the number of nuclei per myotube at 72 h of differentiation. These data demonstrate individual miRNAs regulate genes essential for myogenic satellite cell proliferation and differentiation.

  16. Space Launch Vehicles: Government Activities, Commercial Competition, and Satellite Exports

    DTIC Science & Technology

    2006-03-20

    Relations Authorization Act (P.L. 101-246). At the time, attention was focused on two European companies ( Astrium and Alenia Spazio) that had built...contain U.S. components. In August 2001, INTELSAT canceled its contract with Astrium for the APR-3 satellite, citing several factors, including the delay

  17. Rat soleus muscle satellite cells during the recovery after gravitational unloading

    NASA Astrophysics Data System (ADS)

    Turtikova, Olga; Shenkman, Boris; Altaeva, Erzhena; Leinsoo, Toomas

    In this study the attempt was made to assess alterations of rat soleus satellite cell (SC) population during muscle regrowth after 14-day gravitational unloading (using the hindlimb suspension model). Myofiber size increases during the recovery period. SCs are supposed to participate in muscle growth by fusion with myofibers and supplying them with new myonuclei [Mitchell PO, Pavlath GK, 2001; Oishi Y., 2008]. Other points of view are known about SC participation in the recovery of atrophied muscle mass during the readaptation period [Bruusgaard J.C. et al., 2011; Jackson JR et al., 2012]. After 2 weeks of hindlimb suspension mki67 expression was fivefold lower as compared to control animals and increased gradually up to 28 times by the day 7 of reloading. Cdh15 was decreased after hindlimb unloading and rose from the 1st day of reloading. The expression reached control level to the day 7th of reloading. Cellular response was going on concurrently with the spike of IGF-1 blood level and the increase in muscle IGF-1 concentration. It is possible that in the early days of reloading period differentiation and fusion of satellite cells which were active by the end of hindlimb suspension occurred. Satellite cell incorporation was assessed by counting the amount of BrdU+ myonuclei under myofiber dystrophin layer. It came more intensively in the 1st day of readaptation. It is in accordance with the 4,5 time increase in myogenin expression as compared to hindlimb suspended animals detected at the same time point. Myogenin expression 3 fold decreased by 3rd day of readaptation. We observed only the tendency of resizing but no significant changes in in myonuclear domain size. The number of myonuclei per myofiber cross section was decreased after hindlimb suspension and was not restored by the day 14th of readaptation. Cdh15 and myogenin expression at some extent stabilized after 7 days of readaptation, but high mki67 level pointed to intensive proliferation, which could

  18. Nitric Oxide-Proton Stimulation of Trigeminal Ganglion Neurons Increases MAP Kinase and Phosphatase Expression in Neurons and Satellite Glial Cells

    PubMed Central

    Freeman, Stacy E.; Patil, Vinit V.; Durham, Paul L.

    2008-01-01

    Elevated nitric oxide (NO) and proton levels in synovial fluid are implicated in joint pathology. However, signaling pathways stimulated by these molecules that mediate inflammation and pain in the temporomandibular joint (TMJ) have not been investigated. The goal of this study was to determine the effect of NO-proton stimulation of trigeminal neurons on the in vivo expression of mitogen-activated protein kinases (MAPKs) and phosphatases (MKPs) in trigeminal ganglion neurons and satellite glial cells. Low levels of the active MAPKs ERK, JNK, and p38 were localized in the cytosol of neurons and satellite glial cells in unstimulated animals. However, increased levels of active ERK and p38, but not JNK, were detected in the cytosol and nucleus of V3 neurons and satellite glial cells 15 min and 2 h following bilateral TMJ injections of a NO donor diluted in pH 5.5 medium. While ERK levels returned to near basal levels 24 h after stimulation, p38 levels remained significantly elevated. In contrast to MKP-2 and MKP-3 levels that were barely detectable in neurons or satellite glial cells, MKP-1 staining was readily observed in satellite glial cells in ganglia from unstimulated animals. However, neuronal and satellite glial cell staining for MKP-1, MKP-2, and MKP-3 were all significantly increased in response to NO-protons. Increased active ERK and p38 levels as well as elevated MKP levels were also detected in neurons and satellite glial cells located in V2 and V1 regions of the ganglion. Our data provide evidence that NO-proton stimulation of V3 neurons results in temporal and spatial changes in expression of active ERK and p38 and MKPs in all regions of the ganglion. We propose that in trigeminal ganglia these cellular events, which are involved in peripheral sensitization as well as control of inflammatory and nociceptive responses, may play a role in TMJ pathology. PMID:18938228

  19. An Active K-Band Receive Slot Array for Mobile Satellite Communications

    NASA Technical Reports Server (NTRS)

    Tulintseff, A. N.; Lee, K. A.; Sukamto, L. M.; Chew, W.

    1994-01-01

    An active receive slot array has been developed for operation in the downlink frequency band, 19.914-20.064 GHz, of NASA's Advanced Communication Technology Satellite (ACTS) for the ACTS Mobile Terminal (AMT) project.

  20. Growth and sex effects on the expression of syndecan-4 and glypican-1 in turkey myogenic satellite cell populations.

    PubMed

    Song, Yan; McFarland, Douglas C; Velleman, Sandra G

    2013-06-01

    The adult skeletal muscle stem cells, satellite cells, are responsible for skeletal muscle growth and regeneration. Satellite cells represent a heterogeneous cell population that differentially express cell surface markers. The membrane-associated heparan sulfate proteoglycans, syndecan-4, and glypican-1, are differentially expressed by satellite cells during the proliferation and differentiation stages of satellite cells. However, how the population of syndecan-4- or glypican-1-positive satellite cells changes during proliferation and differentiation, and how sex and muscle growth potential affect the expression of these genes is unknown. Differences in the amount of satellite cells positive for syndecan-4 or glypican-1 would affect the process of proliferation and differentiation which would impact both muscle mass accretion and the regeneration of muscle. In the current study, the percentage of satellite cells positive for syndecan-4 or glypican-1 from male and female turkeys from a Randombred Control Line 2 and a line (F) selected for increased 16-week body weight were measured during proliferation and differentiation. Growth selection altered the population of syndecan-4- and glypican-1-positive satellite cells and there were sex differences in the percentage of syndecan-4- and glypican-1-positive satellite cells. This study provides new information on dynamic changes in syndecan-4- and glypican-1-positive satellite cells showing that they are differentially expressed during myogenesis and growth selection and sex affects their expression.

  1. Systemic inflammation alters satellite glial cell function and structure. A possible contribution to pain.

    PubMed

    Blum, E; Procacci, P; Conte, V; Hanani, M

    2014-08-22

    Local peripheral injury activates satellite glial cells (SGCs) in sensory ganglia, which may contribute to chronic pain. We hypothesized that systemic inflammation affects sensory ganglia like local injury. We induced systemic inflammation in mice by injecting lipopolysaccharide (LPS) intraperitoneally, and characterized SGCs and neurons in dorsal root ganglia (DRG), using dye injection, calcium imaging, electron microscopy (EM), immunohistochemistry, and electrical recordings. Several days post-LPS, SGCs were activated, and dye coupling among SGCs increased 3-4.5-fold. EM showed abnormal growth of SGC processes and the formation of new gap junctions. Sensitivity of SGCs to ATP increased twofold, and neuronal excitability was augmented. Blocking gap junctions reduced pain behavior in LPS-treated mice. Thus, changes in DRG due to systemic inflammation are similar to those due to local injury, which may explain the pain in sickness behavior and in other systemic diseases.

  2. Hepatocyte Growth Factor-mediated satellite cells niche perturbation promotes development of distinct sarcoma subtypes

    PubMed Central

    Morena, Deborah; Maestro, Nicola; Bersani, Francesca; Forni, Paolo Emanuele; Lingua, Marcello Francesco; Foglizzo, Valentina; Šćepanović, Petar; Miretti, Silvia; Morotti, Alessandro; Shern, Jack F; Khan, Javed; Ala, Ugo; Provero, Paolo; Sala, Valentina; Crepaldi, Tiziana; Gasparini, Patrizia; Casanova, Michela; Ferrari, Andrea; Sozzi, Gabriella; Chiarle, Roberto; Ponzetto, Carola; Taulli, Riccardo

    2016-01-01

    Embryonal Rhabdomyosarcoma (ERMS) and Undifferentiated Pleomorphic Sarcoma (UPS) are distinct sarcoma subtypes. Here we investigate the relevance of the satellite cell (SC) niche in sarcoma development by using Hepatocyte Growth Factor (HGF) to perturb the niche microenvironment. In a Pax7 wild type background, HGF stimulation mainly causes ERMS that originate from satellite cells following a process of multistep progression. Conversely, in a Pax7 null genotype ERMS incidence drops, while UPS becomes the most frequent subtype. Murine EfRMS display genetic heterogeneity similar to their human counterpart. Altogether, our data demonstrate that selective perturbation of the SC niche results in distinct sarcoma subtypes in a Pax7 lineage-dependent manner, and define a critical role for the Met axis in sarcoma initiation. Finally, our results provide a rationale for the use of combination therapy, tailored on specific amplifications and activated signaling pathways, to minimize resistance emerging from sarcomas heterogeneity. DOI: http://dx.doi.org/10.7554/eLife.12116.001 PMID:26987019

  3. Bmp signaling at the tips of skeletal muscles regulates the number of fetal muscle progenitors and satellite cells during development.

    PubMed

    Wang, Hui; Noulet, Fanny; Edom-Vovard, Frédérique; Tozer, Samuel; Le Grand, Fabien; Duprez, Delphine

    2010-04-20

    Muscle progenitors, labeled by the transcription factor Pax7, are responsible for muscle growth during development. The signals that regulate the muscle progenitor number during myogenesis are unknown. We show, through in vivo analysis, that Bmp signaling is involved in regulating fetal skeletal muscle growth. Ectopic activation of Bmp signaling in chick limbs increases the number of fetal muscle progenitors and fibers, while blocking Bmp signaling reduces their numbers, ultimately leading to small muscles. The Bmp effect that we observed during fetal myogenesis is diametrically opposed to that previously observed during embryonic myogenesis and that deduced from in vitro work. We also show that Bmp signaling regulates the number of satellite cells during development. Finally, we demonstrate that Bmp signaling is active in a subpopulation of fetal progenitors and satellite cells at the extremities of muscles. Overall, our results show that Bmp signaling plays differential roles in embryonic and fetal myogenesis.

  4. The transcription factor Prox1 is essential for satellite cell differentiation and muscle fibre-type regulation

    PubMed Central

    Kivelä, Riikka; Salmela, Ida; Nguyen, Yen Hoang; Petrova, Tatiana V.; Koistinen, Heikki A.; Wiener, Zoltan; Alitalo, Kari

    2016-01-01

    The remarkable adaptive and regenerative capacity of skeletal muscle is regulated by several transcription factors and pathways. Here we show that the transcription factor Prox1 is an important regulator of myoblast differentiation and of slow muscle fibre type. In both rodent and human skeletal muscles Prox1 is specifically expressed in slow muscle fibres and in muscle stem cells called satellite cells. Prox1 activates the NFAT signalling pathway and is necessary and sufficient for the maintenance of the gene program of slow muscle fibre type. Using lineage-tracing we show that Prox1-positive satellite cells differentiate into muscle fibres. Furthermore, we provide evidence that Prox1 is a critical transcription factor for the differentiation of myoblasts via bi-directional crosstalk with Notch1. These results identify Prox1 as an essential transcription factor that regulates skeletal muscle phenotype and myoblast differentiation by interacting with the NFAT and Notch pathways. PMID:27731315

  5. Radio detection of thunderstorm activity with an earth-orbiting satellite

    NASA Technical Reports Server (NTRS)

    Herman, J. R.; Stone, R. G.; Caruso, J. A.

    1975-01-01

    A study was made to determine the feasibility of using artificial earth satellites to monitor thunderstorm activity. The nighttime noise-temperature measurements made with the earth-oriented vee antenna of the Radio Astronomy Explorer (RAE 1) satellite in the frequency range 0.2-9.2 MHz were correlated with reported surface thunderstorm activity. Analysis shows that the minimum nighttime HF noise level (in the absence of surface thunderstorms) at an altitude of 5850 km over the United States is fixed by man-made noise. When thunderstorms are active below the satellite, the noise level is increased by about 6-12 dB. The highest level is associated with the most intense storms. It is concluded that thunderstorm regions can be detected by an orbiting satellite using HF radio techniques, but ionospheric effects must be taken into account.

  6. Geomagnetic Activity and the Equatorial Scintillation of Satellite Signals.

    DTIC Science & Technology

    1980-05-19

    BEORE COMPLETING FORM i. �T NUMBER 2 GOVT ACCESSION No. 3 . RECIPIENT’S CATALOG NUMBER NOSC Technical Report 554 (TR 554) /. 4. TITLE (and SW 441111...Occurrence and intensity of equatorial scintillation have been correlated with daily summed geomagnetic 3 -hour Kp indices, through scintillation data from...satellites at two elevation angles for uhf and 1--hand. They also have been correlated with the individual 3 -hour Kp indices and the correlations

  7. Effect of Bone Marrow Mesenchymal Stem Cells on Satellite Cell Proliferation and Apoptosis in Immobilization-Induced Muscle Atrophy in Rats

    PubMed Central

    Li, Tie-Shan; Shi, Hao; Wang, Lin; Yan, Chuan-Zhu

    2016-01-01

    Background Muscle atrophy due to disuse occurs along with adverse physiological and functional changes, but bone marrow stromal cells (MSCs) may be able to act as muscle satellite cells to restore myofibers. Thus, we investigated whether MSCs could enhance the proliferation of satellite cells and suppress myonuclear apoptosis during immobilization. Material/Methods We isolated, purified, amplified, and identified MSCs. Rats (n=48) were randomized into 3 groups: WB group (n=16), IM-PBS group (n=16), and IM-MSC (n=16). Rat hind limbs were immobilized for 14 d, treated with MSCs or phosphate-buffered saline (PBS), and then studied using immunohistochemistry and Western blot analysis to characterize the proteins involved. Apoptosis was assessed by terminal deoxynucleotidyl transferase (TdT)-mediated deoxy-UTP nick end labeling (TUNEL) method. Results We compared muscle mass, cross-sectional areas, and peak tetanic forces and noted insignificant differences between PBS- and MSC-treated animals, but satellite cell proliferation was significantly greater after MSC treatment (p<0.05). Apoptotic myonuclei were reduced (p<0.05) after MSC treatment as well. Pro-apoptotic Bax was down-regulated and anti-apoptotic Bcl-2 and p-Akt protein were upregulated (p<0.05). Conclusions MSCs injected during hind limb immobilization can maintain satellite cell activity by suppressing myonuclear apoptosis. PMID:27898654

  8. Evolution from education to practical use in University of Tokyo's nano-satellite activities

    NASA Astrophysics Data System (ADS)

    Nakasuka, Shinichi; Sako, Nobutada; Sahara, Hironori; Nakamura, Yuya; Eishima, Takashi; Komatsu, Mitsuhito

    2010-04-01

    The paper overviews recent nano-satellite development activities of University of Tokyo, Intelligent Space Systems Laboratory (ISSL). Development of real satellites and actually launching them provides excellent materials for space engineering education as well as project management, which is rather difficult to teach in usual class lectures. In addition, it may lead to a new way of space development with its cheap and quick access to space. Two educational CubeSats were launched successfully in 2003 and 2005, and they have been surviving in space more than 5 years, which showed that the COTS (commercial off the shelf) can be reliably used in space if the system is designed appropriately. Based on the experiences and technologies obtained in CubeSat projects, ISSL initiated practical applications of nano-satellite, starting with PRISM, 8 kg remote sensing satellite aiming for 30 m ground resolution and Nano-JASMINE, 20 kg astrometry satellite, which will be launched in 2009 and 2010, respectively. In order to support these kinds of student-oriented activities in Japan, University Space Engineering Consortium (UNISEC) was founded in 2002 by the author's group, which has had large effect of further facilitating students' space-related activities in Japan. Significance and history of such activities are reviewed briefly, followed by the objectives and future vision of such nano-satellite activities.

  9. Precocious glucocorticoid exposure reduces skeletal muscle satellite cells in the fetal rat.

    PubMed

    Gokulakrishnan, Ganga; Chang, Xiaoyan; Fleischmann, Ryan; Fiorotto, Marta L

    2017-03-01

    Perinatal skeletal muscle growth rates are a function of protein and myonuclear accretion. Precocious exposure of the fetus to glucocorticoids (GLC) in utero impairs muscle growth. Reduced muscle protein synthesis rates contribute to this response, but the consequences for myonuclear hyperplasia are unknown. To test the hypothesis that blunting of Pax7+ muscle progenitor cell proliferative activity by GLC in vivo also contributes to reduced fetal muscle growth, pregnant rats were administered dexamethasone (DEX: 1 mg/L drinking water) from embryonic day (ED) 13 to ED21. Their responses were compared to pair-fed (PF) and ad libitum-fed controls (CON). Bromodeoxyuridine (BrdU) was administered before delivery to measure myonuclear accretion. Fetal hind limb and diaphragm muscles were collected at term and analyzed for myofiber cross-sectional area (CSA), total and BrdU+ myonuclei, Pax7+ nuclei, MyoD and myogenin protein and mRNA abundance and myosin heavy chain (MyHC) isoform composition. Mean fiber CSA, myonuclei/myofiber and Pax7+ nuclei/myofiber ratios were reduced in DEX compared to those in CON and PF muscles; CSA/myonucleus, BrdU+/total myonuclei and BrdU+ myonuclei/Pax7+ nuclei were similar among groups. Myogenin abundance was reduced and MyHC-slow was increased in DEX fetuses. The data are consistent with GLC inhibition of muscle progenitor cell proliferation limiting satellite cell and myonuclear accretion. The response of PF-fed compared to CON muscles indicated that decreased food consumption by DEX dams contributed to the smaller myofiber CSA but did not affect Pax7+ nuclear accretion. Thus, the effect on satellite cell reserve and myonuclear number also contributes to the blunting of fetal muscle growth by GLC.

  10. UTX demethylase activity is required for satellite cell–mediated muscle regeneration

    PubMed Central

    Wang, Chaochen; Nakka, Kiran; Benyoucef, Aissa; Sebastian, Soji; Zhuang, Lenan; Chu, Alphonse; Palii, Carmen G.; Camellato, Brendan; Brand, Marjorie

    2016-01-01

    The X chromosome–encoded histone demethylase UTX (also known as KDM6A) mediates removal of repressive trimethylation of histone H3 lysine 27 (H3K27me3) to establish transcriptionally permissive chromatin. Loss of UTX in female mice is embryonic lethal. Unexpectedly, male UTX-null mice escape embryonic lethality due to expression of UTY, a paralog that lacks H3K27 demethylase activity, suggesting an enzyme-independent role for UTX in development and thereby challenging the need for active H3K27 demethylation in vivo. However, the requirement for active H3K27 demethylation in stem cell–mediated tissue regeneration remains untested. Here, we employed an inducible mouse KO that specifically ablates Utx in satellite cells (SCs) and demonstrated that active H3K27 demethylation is necessary for muscle regeneration. Loss of UTX in SCs blocked myofiber regeneration in both male and female mice. Furthermore, we demonstrated that UTX mediates muscle regeneration through its H3K27 demethylase activity, as loss of demethylase activity either by chemical inhibition or knock-in of demethylase-dead UTX resulted in defective muscle repair. Mechanistically, dissection of the muscle regenerative process revealed that the demethylase activity of UTX is required for expression of the transcription factor myogenin, which in turn drives differentiation of muscle progenitors. Thus, we have identified a critical role for the enzymatic activity of UTX in activating muscle-specific gene expression during myofiber regeneration and have revealed a physiological role for active H3K27 demethylation in vivo. PMID:26999603

  11. Active subspace approach to reliability and safety assessments of small satellite separation

    NASA Astrophysics Data System (ADS)

    Hu, Xingzhi; Chen, Xiaoqian; Zhao, Yong; Tuo, Zhouhui; Yao, Wen

    2017-02-01

    Ever-increasing launch of small satellites demands an effective and efficient computer-aided analysis approach to shorten the ground test cycle and save the economic cost. However, the multiple influencing factors hamper the efficiency and accuracy of separation reliability assessment. In this study, a novel evaluation approach based on active subspace identification and response surface construction is established and verified. The formulation of small satellite separation is firstly derived, including equations of motion, separation and gravity forces, and quantity of interest. The active subspace reduces the dimension of uncertain inputs with minimum precision loss and a 4th degree multivariate polynomial regression (MPR) using cross validation is hand-coded for the propagation and error analysis. A common spring separation of small satellites is employed to demonstrate the accuracy and efficiency of the approach, which exhibits its potential use in widely existing needs of satellite separation analysis.

  12. The structure and distribution of satellite cells of cardiac muscles in decapod crustaceans.

    PubMed

    Midsukami, M

    1981-01-01

    The structure and distribution of satellite cells of cardiac muscles were examined in twenty-one species of animals chosen from each tribe within the order Decapoda (Arthropoda, Crustacea). The satellite cells were found in all animals observed. Most of them are morphologically identical with those described in different striated muscles of other species, but some cells have unusual features. The decapod satellite cell occasionally lies right over the region corresponding to the intercalated disc between the apposed cardiac muscle cells. The cell sends cytoplasmic processes into the adjacent muscle cells, enabling the plasma membrane to make close contact with the cleft opening of the intercalated disc, and with the myofibril at the level of the Z-line. Another characteristic feature is the presence of "paired" cells. Such cells are clearly separated from each other over most of the contact area by the respective plasma membranes, which are smooth in appearance and devoid of specialized regions. The significance of the presence of satellite cells in decapod cardiac muscle and its possible role are discussed and compared with those described for other species.

  13. Temperature effect on proliferation and differentiation of satellite cells from turkeys with different growth rates.

    PubMed

    Clark, D L; Coy, C S; Strasburg, G M; Reed, K M; Velleman, S G

    2016-04-01

    Poultry selected for growth have an inefficient thermoregulatory system and are more sensitive to temperature extremes. Satellite cells are precursors to skeletal muscle and mediate all posthatch muscle growth. Their physiological functions are affected by temperature. The objective of the current study was to determine how temperature affects satellite cells isolated from the pectoralis major (p. major) muscle (breast muscle) of turkeys selected for increased 16 wk body weight (F line) in comparison to a randombred control line (RBC2) from which the F line originated. Pectoralis major muscle satellite cells were thermally challenged by culturing between 33°C and 43°C to analyze the effects of cold and heat on proliferation and differentiation as compared to control temperature of 38°C. Expression levels of myogenic regulatory factors: myogenic differentiation factor 1 (MYOD1) and myogenin (MYOG) were quantified by quantitative polymerase chain reaction (qPCR). At all sampling times, proliferation increased at a linear rate across temperature in both the RBC2 and F lines. Differentiation also increased at a linear rate across temperature from 33 to 41°C at all sampling times in both the F and RBC2 lines. Satellite cells isolated from F line turkeys were more sensitive to both hot and cold temperatures as proliferation and differentiation increased to a greater extent across temperature (33 to 43°C) when compared with the RBC2 line. Expression of MYOD1 and MYOG increased as temperatures increased from 33 to 41°C at all sampling times in both the F and RBC2 lines. These results demonstrate that satellite cell function is sensitive to both cold and hot temperatures and p. major muscle satellite cells from F line turkeys are more sensitive to temperature extremes than RBC2 satellite cells.

  14. Barx2 is expressed in satellite cells and is required for normal muscle growth and regeneration.

    PubMed

    Meech, Robyn; Gonzalez, Katie N; Barro, Marietta; Gromova, Anastasia; Zhuang, Lizhe; Hulin, Julie-Ann; Makarenkova, Helen P

    2012-02-01

    Muscle growth and regeneration are regulated through a series of spatiotemporally dependent signaling and transcriptional cascades. Although the transcriptional program controlling myogenesis has been extensively investigated, the full repertoire of transcriptional regulators involved in this process is far from defined. Various homeodomain transcription factors have been shown to play important roles in both muscle development and muscle satellite cell-dependent repair. Here, we show that the homeodomain factor Barx2 is a new marker for embryonic and adult myoblasts and is required for normal postnatal muscle growth and repair. Barx2 is coexpressed with Pax7, which is the canonical marker of satellite cells, and is upregulated in satellite cells after muscle injury. Mice lacking the Barx2 gene show reduced postnatal muscle growth, muscle atrophy, and defective muscle repair. Moreover, loss of Barx2 delays the expression of genes that control proliferation and differentiation in regenerating muscle. Consistent with the in vivo observations, satellite cell-derived myoblasts cultured from Barx2(-/-) mice show decreased proliferation and ability to differentiate relative to those from wild-type or Barx2(+/-) mice. Barx2(-/-) myoblasts show reduced expression of the differentiation-associated factor myogenin as well as cell adhesion and matrix molecules. Finally, we find that mice lacking both Barx2 and dystrophin gene expression have severe early onset myopathy. Together, these data indicate that Barx2 is an important regulator of muscle growth and repair that acts via the control of satellite cell proliferation and differentiation.

  15. TNF/p38α/polycomb signaling to Pax7 locus in satellite cells links inflammation to the epigenetic control of muscle regeneration.

    PubMed

    Palacios, Daniela; Mozzetta, Chiara; Consalvi, Silvia; Caretti, Giuseppina; Saccone, Valentina; Proserpio, Valentina; Marquez, Victor E; Valente, Sergio; Mai, Antonello; Forcales, Sonia V; Sartorelli, Vittorio; Puri, Pier Lorenzo

    2010-10-08

    How regeneration cues are converted into the epigenetic information that controls gene expression in adult stem cells is currently unknown. We identified an inflammation-activated signaling in muscle stem (satellite) cells, by which the polycomb repressive complex 2 (PRC2) represses Pax7 expression during muscle regeneration. TNF-activated p38α kinase promotes the interaction between YY1 and PRC2, via threonine 372 phosphorylation of EZH2, the enzymatic subunit of the complex, leading to the formation of repressive chromatin on Pax7 promoter. TNF-α antibodies stimulate satellite cell proliferation in regenerating muscles of dystrophic or normal mice. Genetic knockdown or pharmacological inhibition of the enzymatic components of the p38/PRC2 signaling--p38α and EZH2--invariably promote Pax7 expression and expansion of satellite cells that retain their differentiation potential upon signaling resumption. Genetic knockdown of Pax7 impaired satellite cell proliferation in response to p38 inhibition, thereby establishing the biological link between p38/PRC2 signaling to Pax7 and satellite cell decision to proliferate or differentiate.

  16. Light Weight and Flexible Organic Memory Cells for Satellite Application

    DTIC Science & Technology

    2007-11-02

    This Final Report to the AFOSR provides an account of the summary progress that have been achieved on organic bistable device ( OBD ), with primary...focus being on the theoretical modeling and experimental characterization we established for the OBD project and its possibility usage in space...Another achievement involves the selection of a novel class of material used in OBD for satellite application. Finally, we have tested organic

  17. Active Cells for Multifunctional Structures

    DTIC Science & Technology

    2014-09-24

    techniques to explore a variety of cell designs.  Designed a simplified active cell using Nitinol as the actuation method and relying on Joule heating...for contraction of the cell.  Developed manufacturing techniques for reliably creating Nitinol spring coils in a variety of diameters and gauges...design of the active cells to maximum the stroked length of the active cells by tuning the stiffness of a passive spring in parallel with the Nitinol

  18. Characteristics of the Localization of Connexin 43 in Satellite Cells during Skeletal Muscle Regeneration In Vivo.

    PubMed

    Ishido, Minenori; Kasuga, Norikatsu

    2015-04-28

    For myogenesis, new myotubes are formed by the fusion of differentiated myoblasts. In the sequence of events for myotube formation, intercellular communication through gap junctions composed of connexin 43 (Cx43) plays critical roles in regulating the alignment and fusion of myoblasts in advances of myotube formation in vitro. On the other hand, the relationship between the expression patterns of Cx43 and the process of myotube formation in satellite cells during muscle regeneration in vivo remains poorly understood. The present study investigated the relationship between Cx43 and satellite cells in muscle regeneration in vivo. The expression of Cx43 was detected in skeletal muscles on day 1 post-muscle injury, but not in control muscles. Interestingly, the expression of Cx43 was not localized on the inside of the basement membrane of myofibers in the regenerating muscles. Moreover, although the clusters of differentiated satellite cells, which represent a more advanced stage of myotube formation, were observed on the inside of the basement membrane of myofibers in regenerating muscles, the expression of Cx43 was not localized in the clusters of these satellite cells. Therefore, in the present study, it was suggested that Cx43 may not directly contribute to muscle regeneration via satellite cells.

  19. Discovering a one-dimensional active subspace to quantify multidisciplinary uncertainty in satellite system design

    NASA Astrophysics Data System (ADS)

    Hu, Xingzhi; Parks, Geoffrey T.; Chen, Xiaoqian; Seshadri, Pranay

    2016-03-01

    Uncertainty quantification has recently been receiving much attention from aerospace engineering community. With ever-increasing requirements for robustness and reliability, it is crucial to quantify multidisciplinary uncertainty in satellite system design which dominates overall design direction and cost. However, coupled multi-disciplines and cross propagation hamper the efficiency and accuracy of high-dimensional uncertainty analysis. In this study, an uncertainty quantification methodology based on active subspaces is established for satellite conceptual design. The active subspace effectively reduces the dimension and measures the contributions of input uncertainties. A comprehensive characterization of associated uncertain factors is made and all subsystem models are built for uncertainty propagation. By integrating a system decoupling strategy, the multidisciplinary uncertainty effect is efficiently represented by a one-dimensional active subspace for each design. The identified active subspace is checked by bootstrap resampling for confidence intervals and verified by Monte Carlo propagation for the accuracy. To show the performance of active subspaces, 18 uncertainty parameters of an Earth observation small satellite are exemplified and then another 5 design uncertainties are incorporated. The uncertainties that contribute the most to satellite mass and total cost are ranked, and the quantification of high-dimensional uncertainty is achieved by a relatively small number of support samples. The methodology with considerably less cost exhibits high accuracy and strong adaptability, which provides a potential template to tackle multidisciplinary uncertainty in practical satellite systems.

  20. Sensitivity of muscle satellite cells to pollutants: an in vitro and in vivo comparative approach.

    PubMed

    Fauconneau, B; Paboeuf, G

    2001-08-01

    Muscle satellite cells from rainbow trout were exposed in vitro to increasing concentrations of different xenobiotics: copper, dichloroaniline, prochloraz, nonyl-phenol polyethexylate. Mortality and proliferation rate were measured by Hoechst binding and BrdU incorporation. Dose dependent effect of copper on survival and proliferation was observed with an EC50 at 100 microM. A dose dependent effect of nonyl-phenol diethoxylate was observed on survival with an EC50 at 100 microM. This was associated with a biphasic effect on proliferation rate observed both for nonyl-phenol di and poly-ethoxylate: a stimulation of proliferation at low concentration and an inhibition proliferation at large concentration. These effects were related to the inhibition of cells adhesion through the detergent capacity of nonyl-phenol polyethoxylate. The effects of prochloraze and dichloroaniline on cells mortality (EC 50 > 500 microM) and proliferation rate (LOEC: 100 microM) were limited. Whole fish growth, muscle fibre size distribution and satellite cells survival and proliferation were measured on rainbow trout (60-80 g BW) exposed to two concentrations of prochloraze (10 and 100 microg/ml) or nonyl phenol diethoxylate IGEPAL 210 (100 and 400 microg/ml) during 14 and 10 days exposure, respectively. Muscle fibre size distribution and satellite cells proliferation were affected by prochloraz exposure in vivo and this could be related to the alteration in fish feeding status. The exposure to IGEPAL 210 affected the number of satellite cells extracted and induce a biphasic effect on satellite cells proliferation similar to that observed in vivo. The combined exposure to IGEPAL 210 and prochloraze revealed additive effects of these two compounds. The in vivo and in vitro comparison demonstrated that in vitro satellite cells system could be used as a valuable tool to test the effects of pollutants.

  1. Characterisation of equine satellite cell transcriptomic profile response to β-hydroxy-β-methylbutyrate (HMB).

    PubMed

    Szcześniak, Katarzyna A; Ciecierska, Anna; Ostaszewski, Piotr; Sadkowski, Tomasz

    2016-10-01

    β-Hydroxy-β-methylbutyrate (HMB) is a popular ergogenic aid used by human athletes and as a supplement to sport horses, because of its ability to aid muscle recovery, improve performance and body composition. Recent findings suggest that HMB may stimulate satellite cells and affect expressions of genes regulating skeletal muscle cell growth. Despite the scientific data showing benefits of HMB supplementation in horses, no previous study has explained the mechanism of action of HMB in this species. The aim of this study was to reveal the molecular background of HMB action on equine skeletal muscle by investigating the transcriptomic profile changes induced by HMB in equine satellite cells in vitro. Upon isolation from the semitendinosus muscle, equine satellite cells were cultured until the 2nd day of differentiation. Differentiating cells were incubated with HMB for 24 h. Total cellular RNA was isolated, amplified, labelled and hybridised to microarray slides. Microarray data validation was performed with real-time quantitative PCR. HMB induced differential expressions of 361 genes. Functional analysis revealed that the main biological processes influenced by HMB in equine satellite cells were related to muscle organ development, protein metabolism, energy homoeostasis and lipid metabolism. In conclusion, this study demonstrated for the first time that HMB has the potential to influence equine satellite cells by controlling global gene expression. Genes and biological processes targeted by HMB in equine satellite cells may support HMB utility in improving growth and regeneration of equine skeletal muscle; however, the overall role of HMB in horses remains equivocal and requires further proteomic, biochemical and pharmacokinetic studies.

  2. Long term effects of lipopolysaccharide on satellite glial cells in mouse dorsal root ganglia.

    PubMed

    Blum, E; Procacci, P; Conte, V; Sartori, P; Hanani, M

    2017-01-01

    Lipopolysaccharide (LPS) has been used extensively to study neuroinflammation, but usually its effects were examined acutely (24h<). We have shown previously that a single intraperitoneal LPS injection activated satellite glial cells (SGCs) in mouse dorsal root ganglia (DRG) and altered several functional parameters in these cells for at least one week. Here we asked whether the LPS effects would persist for 1 month. We injected mice with a single LPS dose and tested pain behavior, assessed SGCs activation in DRG using glial fibrillary acidic protein (GFAP) immunostaining, and injected a fluorescent dye intracellularly to study intercellular coupling. Electron microscopy was used to quantitate changes in gap junctions. We found that at 30 days post-LPS the threshold to mechanical stimulation was lower than in controls. GFAP expression, as well as the magnitude of dye coupling among SGCs were greater than in controls. Electron microscopy analysis supported these results, showing a greater number of gap junctions and an abnormal growth of SGC processes. These changes were significant, but less prominent than at 7 days post-LPS. We conclude that a single LPS injection exerts long-term behavioral and cellular changes. The results are consistent with the idea that SGC activation contributes to hyperalgesia.

  3. Satellite Cell Functional Alterations Following Cutaneous Burn in rats Include an Increase in Their Osteogenic Potential

    DTIC Science & Technology

    2013-10-07

    Rudnicki M. Muscle satellite cells are multipotential stem cells that exhibit myogenic, osteogenic, and adipogenic differentiation. Differentiation...apoptosis-related genes / proteins in skeletal muscles of rats. Apoptosis 2009;14:52. [22] Stover SL, Niemann KM, Tulloss JR. Experience with surgical

  4. Analytic studies on satellite detection of severe, two-cell tornadoes

    NASA Technical Reports Server (NTRS)

    Carrier, G. F.; Dergarabedian, P.; Fendell, F. E.

    1979-01-01

    It is argued that a two-cell structure is likely to be the unique property, and potentially satellite-accessible observable, of the exceptionally severe tornado. Analysis elucidating the dynamic, thermodynamic, and geometric properties of this two-cell structure is described. The analysis ultimately will furnish instrumentation requirements.

  5. A satellite cell-specific knockout of the androgen receptor reveals myostatin as a direct androgen target in skeletal muscle.

    PubMed

    Dubois, Vanessa; Laurent, Michaël R; Sinnesael, Mieke; Cielen, Nele; Helsen, Christine; Clinckemalie, Liesbeth; Spans, Lien; Gayan-Ramirez, Ghislaine; Deldicque, Louise; Hespel, Peter; Carmeliet, Geert; Vanderschueren, Dirk; Claessens, Frank

    2014-07-01

    Androgens have well-established anabolic actions on skeletal muscle, although the direct effects of the androgen receptor (AR) in muscle remain unclear. We generated satellite cell-specific AR-knockout (satARKO) mice in which the AR is selectively ablated in satellite cells, the muscle precursor cells. Total-limb maximal grip strength is decreased by 7% in satARKO mice, with soleus muscles containing ∼10% more type I fibers and 10% less type IIa fibers than the corresponding control littermates. The weight of the perineal levator ani muscle is markedly reduced (-52%). Thus, muscle AR is involved in fiber-type distribution and force production of the limb muscles, while it is a major determinant of the perineal muscle mass. Surprisingly, myostatin (Mstn), a strong inhibitor of skeletal muscle growth, is one of the most androgen-responsive genes (6-fold reduction in satARKO) through direct transcription activation by the AR. Consequently, muscle hypertrophy in response to androgens is augmented in Mstn-knockout mice. Our finding that androgens induce Mstn signaling to restrain their own anabolic actions has implications for the treatment of muscle wasting disorders.-Dubois, V., Laurent, M. R., Sinnesael, M., Cielen, N., Helsen, C., Clinckemalie, L., Spans, L., Gayan-Ramirez, G., Deldicque, L., Hespel, P., Carmeliet, G., Vanderschueren, D., and Claessens, F. A satellite cell-specific knockout of the androgen receptor reveals myostatin as a direct androgen target in skeletal muscle.

  6. An upward compatible spectrum sharing architecture for existing, actively planned and emerging mobile satellite systems

    NASA Technical Reports Server (NTRS)

    Azarbar, Bahman

    1990-01-01

    Existing and actively planned mobile satellite systems are competing for a viable share of the spectrum allocated by the International Telecommunications Union (ITU) to the satellite based mobile services in the 1.5/1.6 GHz range. The limited amount of spectrum available worldwide and the sheer number of existing and planned mobile satellite systems dictate the adoption of an architecture which will maximize sharing possibilities. A viable sharing architecture must recognize the operational needs and limitations of the existing systems. Furthermore, recognizing the right of access of the future systems as they will emerge in time, the adopted architecture must allow for additional growth and be amenable to orderly introduction of future systems. An attempt to devise such a sharing architecture is described. A specific example of the application of the basic concept to the existing and planned mobile satellite systems is also discussed.

  7. An upward compatible spectrum sharing architecture for existing, actively planned and emerging mobile satellite systems

    NASA Astrophysics Data System (ADS)

    Azarbar, Bahman

    Existing and actively planned mobile satellite systems are competing for a viable share of the spectrum allocated by the International Telecommunications Union (ITU) to the satellite based mobile services in the 1.5/1.6 GHz range. The limited amount of spectrum available worldwide and the sheer number of existing and planned mobile satellite systems dictate the adoption of an architecture which will maximize sharing possibilities. A viable sharing architecture must recognize the operational needs and limitations of the existing systems. Furthermore, recognizing the right of access of the future systems as they will emerge in time, the adopted architecture must allow for additional growth and be amenable to orderly introduction of future systems. An attempt to devise such a sharing architecture is described. A specific example of the application of the basic concept to the existing and planned mobile satellite systems is also discussed.

  8. Functional study of endothelin B receptors in satellite glial cells in trigeminal ganglia.

    PubMed

    Feldman-Goriachnik, Rachel; Hanani, Menachem

    2011-07-13

    There is immunohistochemical evidence for endothelin (ET) receptors in satellite glial cells in sensory ganglia, but there is no information on the function of these receptors. We used calcium imaging to study this question in isolated mouse trigeminal ganglia and found that satellite glial cells are highly sensitive to ET-1, with threshold at 0.05 nM. Responses displayed strong desensitization at ET-1 concentrations of more than 1 nM. A large component of the response persisted when Ca was deleted from the external medium, consistent with Ca release from internal stores. The use of receptor selective agents showed that the responses were mediated by ETB receptors. We conclude that satellite glial cells display endothelin receptors, which may participate in neuron-glia communications in the trigeminal ganglia.

  9. Pancreatic Satellite Cells Derived Galectin-1 Increase the Progression and Less Survival of Pancreatic Ductal Adenocarcinoma

    PubMed Central

    Gao, Jun; Wang, Sen; Ye, Nianyuan; Li, Ping; Gao, Sujun; Miao, Yi; Wang, Daorong; Jiang, Kuirong

    2014-01-01

    Background Galectin-1, a member of carbohydrate-binding proteins with a polyvalent function on tumor progression, was found strongly expressed in pancreatic satellite cells (PSCs), which partner in crime with cancer cells and promote the development of pancreatic ductal adenocarcinoma (PDAC). We evaluated the effects of PSCs derived Galectin-1 on the progression of PDAC, as well as the tumor establishment and development in mouse xenografts. Methods The relationship between immunohistochemistry staining intensity of Galectin-1 and clinicopathologic variables were assessed in 66 PDAC tissues, 18 chronic pancreatitis tissues and 10 normal controls. The roles of PSCs isolated from PDAC and normal pancreas on the proliferative activity, MMP2 and MMP9 expression, and the invasion of CFPAC-1 in the co-cultured system, as well as on the tumor establishment and development in mouse xenografts by mixed implanting with CFPAC-1 subcutaneously were evaluated. Results Galectin-1 expression was gradually increased from normal pancreas (negative), chronic pancreatitis (weak) to PDAC (strong), in which Galectin-1 expression was also increased from well, moderately to poorly differentiated PDAC. Galectin-1 staining intensity of pancreatic cancer tissue was associated with increase in tumor size, lymph node metastasis, perineural invasion and differentiation and UICC stage, and served as the independent prognostic indicator of poor survival of pancreatic cancer. In vitro and in vivo experiments indicated that TGF-β1 upregulated Galectin-1 expression in PSCs, which could further promotes the proliferative activity, MMP2 and MMP9 expression, and invasion of pancreatic cancer cells, as well as the tumor establishment and growth. Conclusion Galectin-1 expression in stromal cells of pancreatic cancer suggests that this protein plays a role in the promotion of cancer cells invasion and metastasis and provides a therapeutic target for the treatment of pancreatic cancer. PMID:24595374

  10. Stochastic cellular automata model of cell migration, proliferation and differentiation: validation with in vitro cultures of muscle satellite cells.

    PubMed

    Garijo, N; Manzano, R; Osta, R; Perez, M A

    2012-12-07

    Cell migration and proliferation has been modelled in the literature as a process similar to diffusion. However, using diffusion models to simulate the proliferation and migration of cells tends to create a homogeneous distribution in the cell density that does not correlate to empirical observations. In fact, the mechanism of cell dispersal is not diffusion. Cells disperse by crawling or proliferation, or are transported in a moving fluid. The use of cellular automata, particle models or cell-based models can overcome this limitation. This paper presents a stochastic cellular automata model to simulate the proliferation, migration and differentiation of cells. These processes are considered as completely stochastic as well as discrete. The model developed was applied to predict the behaviour of in vitro cell cultures performed with adult muscle satellite cells. Moreover, non homogeneous distribution of cells has been observed inside the culture well and, using the above mentioned stochastic cellular automata model, we have been able to predict this heterogeneous cell distribution and compute accurate quantitative results. Differentiation was also incorporated into the computational simulation. The results predicted the myotube formation that typically occurs with adult muscle satellite cells. In conclusion, we have shown how a stochastic cellular automata model can be implemented and is capable of reproducing the in vitro behaviour of adult muscle satellite cells.

  11. Analytical study of pulsed laser irradiation on some materials used for photovoltaic cells on satellites

    NASA Astrophysics Data System (ADS)

    Abd El-Hameed, Afaf M.

    2015-12-01

    The present research concerns on the study of laser-powered solar panels used for space applications. A mathematical model representing the laser effects on semiconductors has been developed. The temperature behavior and heat flow on the surface and through a slab has been studied after exposed to nano-second pulsed laser. The model is applied on two different types of common active semiconductor materials that used for photovoltaic cells fabrication as silicon (Si), and gallium arsenide (GaAs). These materials are used for receivers' manufacture for laser beamed power in space. Various values of time are estimated to clarify the heat flow through the material sample and generated under the effects of pulsed laser irradiation. These effects are theoretically studied in order to determine the performance limits of the solar cells when they are powered by laser radiation during the satellite eclipse. Moreover, the obtained results are carried out to optimize conversion efficiency of photovoltaic cells and may be helpful to give more explanation for layout of the light-electricity space systems.

  12. Skeletal Muscle Satellite Cells, Mitochondria, and MicroRNAs: Their Involvement in the Pathogenesis of ALS.

    PubMed

    Tsitkanou, Stavroula; Della Gatta, Paul A; Russell, Aaron P

    2016-01-01

    Amyotrophic lateral sclerosis (ALS), also known as motor neuron disease (MND), is a fatal motor neuron disorder. It results in progressive degeneration and death of upper and lower motor neurons, protein aggregation, severe muscle atrophy and respiratory insufficiency. Median survival with ALS is between 2 and 5 years from the onset of symptoms. ALS manifests as either familial ALS (FALS) (~10% of cases) or sporadic ALS (SALS), (~90% of cases). Mutations in the copper/zinc (CuZn) superoxide dismutase (SOD1) gene account for ~20% of FALS cases and the mutant SOD1 mouse model has been used extensively to help understand the ALS pathology. As the precise mechanisms causing ALS are not well understood there is presently no cure. Recent evidence suggests that motor neuron degradation may involve a cell non-autonomous phenomenon involving numerous cell types within various tissues. Skeletal muscle is now considered as an important tissue involved in the pathogenesis of ALS by activating a retrograde signaling cascade that degrades motor neurons. Skeletal muscle heath and function are regulated by numerous factors including satellite cells, mitochondria and microRNAs. Studies demonstrate that in ALS these factors show various levels of dysregulation within the skeletal muscle. This review provides an overview of their dysregulation in various ALS models as well as how they may contribute individually and/or synergistically to the ALS pathogenesis.

  13. Impaired energy metabolism of senescent muscle satellite cells is associated with oxidative modifications of glycolytic enzymes.

    PubMed

    Baraibar, Martín A; Hyzewicz, Janek; Rogowska-Wrzesinska, Adelina; Bulteau, Anne-Laure; Prip-Buus, Carina; Butler-Browne, Gillian; Friguet, Bertrand

    2016-12-04

    Accumulation of oxidized proteins is a hallmark of cellular and organismal aging. Adult muscle stem cell (or satellite cell) replication and differentiation is compromised with age contributing to sarcopenia. However, the molecular events related to satellite cell dysfunction during aging are not completely understood. In the present study we have addressed the potential impact of oxidatively modified proteins on the altered metabolism of senescent human satellite cells. By using a modified proteomics analysis we have found that proteins involved in protein quality control and glycolytic enzymes are the main targets of oxidation (carbonylation) and modification with advanced glycation/lipid peroxidation end products during the replicative senescence of satellite cells. Inactivation of the proteasome appeared to be a likely contributor to the accumulation of such damaged proteins. Metabolic and functional analyses revealed an impaired glucose metabolism in senescent cells. A metabolic shift leading to increased mobilization of non-carbohydrate substrates such as branched chain amino acids or long chain fatty acids was observed. Increased levels of acyl-carnitines indicated an increased turnover of storage and membrane lipids for energy production. Taken together, these results support a link between oxidative protein modifications and the altered cellular metabolism associated with the senescent phenotype of human myoblasts.

  14. Impaired energy metabolism of senescent muscle satellite cells is associated with oxidative modifications of glycolytic enzymes

    PubMed Central

    Baraibar, Martín A.; Hyzewicz, Janek; Rogowska-Wrzesinska, Adelina; Bulteau, Anne-Laure; Prip-Buus, Carina; Butler-Browne, Gillian; Friguet, Bertrand

    2016-01-01

    Accumulation of oxidized proteins is a hallmark of cellular and organismal aging. Adult muscle stem cell (or satellite cell) replication and differentiation is compromised with age contributing to sarcopenia. However, the molecular events related to satellite cell dysfunction during aging are not completely understood. In the present study we have addressed the potential impact of oxidatively modified proteins on the altered metabolism of senescent human satellite cells. By using a modified proteomics analysis we have found that proteins involved in protein quality control and glycolytic enzymes are the main targets of oxidation (carbonylation) and modification with advanced glycation/lipid peroxidation end products during the replicative senescence of satellite cells. Inactivation of the proteasome appeared to be a likely contributor to the accumulation of such damaged proteins. Metabolic and functional analyses revealed an impaired glucose metabolism in senescent cells. A metabolic shift leading to increased mobilization of non-carbohydrate substrates such as branched chain amino acids or long chain fatty acids was observed. Increased levels of acyl-carnitines indicated an increased turnover of storage and membrane lipids for energy production. Taken together, these results support a link between oxidative protein modifications and the altered cellular metabolism associated with the senescent phenotype of human myoblasts. PMID:27922824

  15. Pericytes in the myovascular niche promote post-natal myofiber growth and satellite cell quiescence.

    PubMed

    Kostallari, Enis; Baba-Amer, Yasmine; Alonso-Martin, Sonia; Ngoh, Pamela; Relaix, Frederic; Lafuste, Peggy; Gherardi, Romain K

    2015-04-01

    The satellite cells, which serve as adult muscle stem cells, are both located beneath myofiber basement membranes and closely associated with capillary endothelial cells. We observed that 90% of capillaries were associated with pericytes in adult mouse and human muscle. During post-natal growth, newly formed vessels with their neuroglial 2 proteoglycan (NG2)-positive pericytes became progressively associated with the post-natal muscle stem cells, as myofibers increased in size and satellite cells entered into quiescence. In vitro, human muscle-derived pericytes promoted myogenic cell differentiation through insulin-like growth factor 1 (IGF1) and myogenic cell quiescence through angiopoietin 1 (ANGPT1). Diphtheria toxin-induced ablation of muscle pericytes in growing mice led both to myofiber hypotrophy and to impaired establishment of stem cells quiescence. Similar effects were observed following conditional in vivo deletion of pericyte Igf1 and Angpt1 genes, respectively. Our data therefore demonstrate that, by promoting post-natal myogenesis and stem cell quiescence, pericytes play a key role in the microvascular niche of satellite cells.

  16. MyoD-expressing progenitors are essential for skeletal myogenesis and satellite cell development

    PubMed Central

    Wood, William M.; Etemad, Shervin; Yamamoto, Masakazu; Goldhamer, David J.

    2013-01-01

    Skeletal myogenesis in the embryo is regulated by the coordinated expression of the MyoD family of muscle regulatory factors (MRFs). MyoD and Myf-5, which are the primary muscle lineage-determining factors, function in a partially redundant manner to establish muscle progenitor cell identity. Previous diphtheria toxin (DTA)-mediated ablation studies showed that MyoD+ progenitors rescue myogenesis in embryos in which Myf-5-expressing cells were targeted for ablation, raising the possibility that the regulative behavior of distinct, MRF-expressing populations explains the functional compensatory activities of these MRFs. Using MyoDiCre mice, we show that DTA-mediated ablation of MyoD-expressing cells results in the cessation of myogenesis by embryonic day 12.5 (E12.5), as assayed by myosin heavy chain (MyHC) and Myogenin staining. Importantly, MyoDiCre/+;R26DTA/+ embryos exhibited a concomitant loss of Myf-5+ progenitors, indicating that the vast majority of Myf-5+ progenitors express MyoD, a conclusion consistent with immunofluorescence analysis of Myf-5 protein expression in MyoDiCre lineage-labeled embryos. Surprisingly, staining for the paired box transcription factor, Pax7, which functions genetically upstream of MyoD in the trunk and is a marker for fetal myoblasts and satellite cell progenitors, was also lost by E12.5. Specific ablation of differentiating skeletal muscle in ACTA1Cre;R26DTA/+ embryos resulted in comparatively minor effects on MyoD+, Myf-5+ and Pax7+ progenitors, indicating that cell non-autonomous effects are unlikely to explain the rapid loss of myogenic progenitors in MyoDiCre/+;R26DTA/+ embryos. We conclude that the vast majority of myogenic populations transit through a MyoD+ state, and that MyoD+ progenitors are essential for myogenesis and stem cell development. PMID:24055173

  17. Active And Autonomous Balancing System For Satellites Batteries

    NASA Astrophysics Data System (ADS)

    Mosset, E.

    2011-10-01

    Lithium-ion technology offers a great number of advantages, compared to the nickel-cadmium (Ni-Cd) and the nickel-hydrogen (NiH2) ones, and in return, it presents only one major constraint. This unique constraint of lithium-ion technology is linked to the lack of an overcharge mechanism that forbids the overcharge of the lower energy cells, in order to fully charge the higher ones. That means that end of charge sequence shall be carefully controlled, otherwise the lithium-ion cell voltage rises endless (like a capacitor) generating Li-ion plating on the negative electrode leading to a premature ageing (capacity loss & internal resistance increase) or a thermal runaway beyond a threshold. So in order to maximize the energy stored into the cells connected in series and to avoid any risk of overcharge a balancing system is recommended to equalize the state of charge from cell to cell within a cell serial string. Saft is familiar with such systems for various applications and in particular for space applications. However, in order to reduce its cost and improve its efficiency, Saft carry on seeking for innovating solutions. In this frame, a very simple and efficient balancing circuit have been identified which is based on a flight proven component.

  18. Evaluation of solar cells for potential space satellite power applications

    NASA Technical Reports Server (NTRS)

    1977-01-01

    The evaluation focused on the following subjects: (1) the relative merits of alternative solar cell materials, based on performance and availability, (2) the best manufacturing methods for various solar cell options and the effects of extremely large production volumes on their ultimate costs and operational characteristics, (3) the areas of uncertainty in achieving large solar cell production volumes, (4) the effects of concentration ratios on solar array mass and system performance, (5) the factors influencing solar cell life in the radiation environment during transport to and in geosynchronous orbit, and (6) the merits of conducting solar cell manufacturing operations in space.

  19. Muscle Satellite Cells and Endothelial Cells: Close Neighbors and Privileged Partners

    PubMed Central

    Christov, Christo; Chrétien, Fabrice; Abou-Khalil, Rana; Bassez, Guillaume; Vallet, Grégoire; Authier, François-Jérôme; Bassaglia, Yann; Shinin, Vasily; Tajbakhsh, Shahragim; Chazaud, Bénédicte

    2007-01-01

    Genetically engineered mice (Myf5nLacZ/+, Myf5GFP-P/+) allowing direct muscle satellite cell (SC) visualization indicate that, in addition to being located beneath myofiber basal laminae, SCs are strikingly close to capillaries. After GFP+ bone marrow transplantation, blood-borne cells occupying SC niches previously depleted by irradiation were similarly detected near vessels, thereby corroborating the anatomical stability of juxtavascular SC niches. Bromodeoxyuridine pulse-chase experiments also localize quiescent and less quiescent SCs near vessels. SCs, and to a lesser extent myonuclei, were nonrandomly associated with capillaries in humans. Significantly, they were correlated with capillarization of myofibers, regardless to their type, in normal muscle. They also varied in paradigmatic physiological and pathological situations associated with variations of capillary density, including amyopathic dermatomyositis, a unique condition in which muscle capillary loss occurs without myofiber damage, and in athletes in whom capillaries increase in number. Endothelial cell (EC) cultures specifically enhanced SC growth, through IGF-1, HGF, bFGF, PDGF-BB, and VEGF, and, accordingly, cycling SCs remained mainly juxtavascular. Conversely, differentiating myogenic cells were both proangiogenic in vitro and spatiotemporally associated with neoangiogenesis in muscular dystrophy. Thus, SCs are largely juxtavascular and reciprocally interact with ECs during differentiation to support angio-myogenesis. PMID:17287398

  20. Muscle satellite cells and endothelial cells: close neighbors and privileged partners.

    PubMed

    Christov, Christo; Chrétien, Fabrice; Abou-Khalil, Rana; Bassez, Guillaume; Vallet, Grégoire; Authier, François-Jérôme; Bassaglia, Yann; Shinin, Vasily; Tajbakhsh, Shahragim; Chazaud, Bénédicte; Gherardi, Romain K

    2007-04-01

    Genetically engineered mice (Myf5nLacZ/+, Myf5GFP-P/+) allowing direct muscle satellite cell (SC) visualization indicate that, in addition to being located beneath myofiber basal laminae, SCs are strikingly close to capillaries. After GFP(+) bone marrow transplantation, blood-borne cells occupying SC niches previously depleted by irradiation were similarly detected near vessels, thereby corroborating the anatomical stability of juxtavascular SC niches. Bromodeoxyuridine pulse-chase experiments also localize quiescent and less quiescent SCs near vessels. SCs, and to a lesser extent myonuclei, were nonrandomly associated with capillaries in humans. Significantly, they were correlated with capillarization of myofibers, regardless to their type, in normal muscle. They also varied in paradigmatic physiological and pathological situations associated with variations of capillary density, including amyopathic dermatomyositis, a unique condition in which muscle capillary loss occurs without myofiber damage, and in athletes in whom capillaries increase in number. Endothelial cell (EC) cultures specifically enhanced SC growth, through IGF-1, HGF, bFGF, PDGF-BB, and VEGF, and, accordingly, cycling SCs remained mainly juxtavascular. Conversely, differentiating myogenic cells were both proangiogenic in vitro and spatiotemporally associated with neoangiogenesis in muscular dystrophy. Thus, SCs are largely juxtavascular and reciprocally interact with ECs during differentiation to support angio-myogenesis.

  1. Fluorescence activated cell sorting.

    NASA Technical Reports Server (NTRS)

    Bonner, W. A.; Hulett, H. R.; Sweet, R. G.; Herzenberg, L. A.

    1972-01-01

    An instrument has been developed for sorting biological cells. The cells are rendered differentially fluorescent and incorporated into a small liquid stream illuminated by a laser beam. The cells pass sequentially through the beam, and fluorescent light from the cells gives rise to electrical signals. The stream is broken into a series of uniform size drops downstream of the laser. The cell signals are used to give appropriate electrostatic charges to drops containing the cells. The drops then pass between two charged plates and are deflected to appropriate containers. The system has proved capable of providing fractions containing large numbers of viable cells highly enriched in a particular functional type.

  2. Reduced myotube diameter, atrophic signalling and elevated oxidative stress in cultured satellite cells from COPD patients.

    PubMed

    Pomiès, Pascal; Rodriguez, Julie; Blaquière, Marine; Sedraoui, Sami; Gouzi, Fares; Carnac, Gilles; Laoudj-Chenivesse, Dalila; Mercier, Jacques; Préfaut, Christian; Hayot, Maurice

    2015-01-01

    The mechanisms leading to skeletal limb muscle dysfunction in chronic obstructive pulmonary disease (COPD) have not been fully elucidated. Exhausted muscle regenerative capacity of satellite cells has been evocated, but the capacity of satellite cells to proliferate and differentiate properly remains unknown. Our objectives were to compare the characteristics of satellite cells derived from COPD patients and healthy individuals, in terms of proliferative and differentiation capacities, morphological phenotype and atrophy/hypertrophy signalling, and oxidative stress status. Therefore, we purified and cultivated satellite cells from progressively frozen vastus lateralis biopsies of eight COPD patients and eight healthy individuals. We examined proliferation parameters, differentiation capacities, myotube diameter, expression of atrophy/hypertrophy markers, oxidative stress damages, antioxidant enzyme expression and cell susceptibility to H2 O2 in cultured myoblasts and/or myotubes. Proliferation characteristics and commitment to terminal differentiation were similar in COPD patients and healthy individuals, despite impaired fusion capacities of COPD myotubes. Myotube diameter was smaller in COPD patients (P = 0.015), and was associated with a higher expression of myostatin (myoblasts: P = 0.083; myotubes: P = 0.050) and atrogin-1 (myoblasts: P = 0.050), and a decreased phospho-AKT/AKT ratio (myoblasts: P = 0.022). Protein carbonylation (myoblasts: P = 0.028; myotubes: P = 0.002) and lipid peroxidation (myotubes: P = 0.065) were higher in COPD cells, and COPD myoblasts were significantly more susceptible to oxidative stress. Thus, cultured satellite cells from COPD patients display characteristics of morphology, atrophic signalling and oxidative stress similar to those described in in vivo COPD skeletal limb muscles. We have therefore demonstrated that muscle alteration in COPD can be studied by classical in vitro cellular models.

  3. The effect of nutritional status on myogenic gene expression of satellite cells derived from different muscle types.

    PubMed

    Powell, D J; McFarland, D C; Cowieson, A J; Muir, W I; Velleman, S G

    2014-09-01

    Satellite cells (SC) are a multipotential stem cell population responsible for facilitating posthatch muscle fiber hypertrophy. The proliferation and differentiation of SC is sensitive to nutritional regimen, and the SC response to nutrition varies depending upon their muscle type of origin. The objective of the current study was to determine the effect of altering protein synthesis on the expression of several key genes regulating SC activity and the effect of muscle type. Satellite cells isolated from the fast glycolytic pectoralis major and the fast oxidative and glycolytic biceps femoris were studied. These genes included the myogenic regulatory factors myogenic determination factor 1 (MyoD) and myogenin, the cell-membrane associated proteoglycans syndecan-4 and glypican-1, the extracellular matrix proteoglycan decorin, and the transcription factor paired box 7. Protein synthesis potential varied by the concentration of the sulfur amino acids Met and Cys during SC proliferation and differentiation. The SC were cultured and treated with 1 of 6 Met/Cys concentrations: 60/192, 30/96 (control), 7.5/24, 3.0/9.6, 1.0/3.2, or 0/0 mg/L. A consistent pattern of gene expression emerged following Met/Cys manipulation as increasing reductions in mRNA expression for all genes were observed as Met/Cys concentration decreased, whereas increased Met/Cys concentration caused either no change or had a small negative effect on mRNA expression. Reduced paired box 7 expression would limit myogenic specification of SC, whereas decreased myogenic regulatory factor expression would affect subsequent myogenic development of the SC. Decreased levels of decorin affect SC response to growth factors like myostatin and transforming growth factor β, and extracellular matrix organization. These data highlight the importance of nutrition on the expression of genes critical for satellite cell activation, proliferation and differentiation, and growth factor signal transduction.

  4. Early posthatch starvation decreases satellite cell proliferation and skeletal muscle growth in chicks.

    PubMed

    Halevy, O; Geyra, A; Barak, M; Uni, Z; Sklan, D

    2000-04-01

    The effect of posthatch starvation on skeletal muscle growth and satellite cell proliferation was examined in chicks. Chicks were either fed or starved for 48 h posthatch (d 0-d 2, d 2-d 4 or d 4-d 6) and then refed for 41 d. Body and breast muscle weights were significantly lower in starved chicks than in fed controls throughout the experiment. Histochemical staining revealed that skeletal muscle fiber development in the starved group lagged behind that of the fed group. Starvation from d 2 to 4 and d 4 to 6 posthatch had a progressively lesser effect than did immediate posthatch starvation (P < 0.05). In vitro culturing of breast muscle satellite cells revealed that DNA synthesis and number of cells per gram of muscle in the fed chicks peaked on d 2 and d 3, and then declined. In contrast, DNA synthesis in the cells of starved chicks declined on d 2 and increased on d 3 when chicks were refed. A similar pattern was seen for the number of cells per gram muscle; however, in general cell numbers tended to be higher in the starved group than in controls (P < 0.1). The results obtained with cultured cells were parallel with in situ immunostaining with 5-bromo-2'-deoxyuridine and proliferating cell nuclear antigen in breast muscle from experimental chicks, and with growth hormone receptor expression. These results suggest that satellite cell cultures are a reliable tool for evaluating muscle growth in postnatal chickens. We conclude that sufficient feed in the immediate postnatal period is critical for satellite cell proliferation and skeletal muscle development and is thus important for optimal muscle growth.

  5. Solar attitude control including active nutation damping in a fixed-momentum wheel satellite

    NASA Astrophysics Data System (ADS)

    Azor, Ruth

    1992-08-01

    In geostationary cruise of a momentum biased satellite, it is necessary to stabilize the roll/yaw attitude due to disturbances, caused mainly by solar pressure. This work presents a roll/yaw control, which is obtained by the use of solar arrays and fixed flaps as actuators, with a horizon sensor for roll measurement. The design also includes an active nutation damping.

  6. Solar sail attitude control including active nutation damping in a fixed-momentum wheel satellite

    NASA Technical Reports Server (NTRS)

    Azor, Ruth

    1992-01-01

    In geostationary cruise of a momentum biased satellite, it is necessary to stabilize the roll/yaw attitude due to disturbances, caused mainly by solar radiation pressure. This work presents a roll/yaw control which is obtained by the use of solar arrays and fixed flaps as actuators, with a horizon sensor for roll measurement. The design also includes an active nutation damping.

  7. Expression of CCAAT/Enhancer Binding Protein Beta in Muscle Satellite Cells Inhibits Myogenesis in Cancer Cachexia

    PubMed Central

    Marchildon, François; Lamarche, Émilie; Lala-Tabbert, Neena; St-Louis, Catherine; Wiper-Bergeron, Nadine

    2015-01-01

    Cancer cachexia is a paraneoplastic syndrome that causes profound weight loss and muscle mass atrophy and is estimated to be the cause of up to 30% of cancer deaths. Though the exact cause is unknown, patients with cancer cachexia have increased muscle protein catabolism. In healthy muscle, injury activates skeletal muscle stem cells, called satellite cells, to differentiate and promote regeneration. Here, we provide evidence that this mechanism is inhibited in cancer cachexia due to persistent expression of CCAAT/Enhancer Binding Protein beta (C/EBPβ) in muscle myoblasts. C/EBPβ is a bzip transcription factor that is expressed in muscle satellite cells and is normally downregulated upon differentiation. However, in myoblasts exposed to a cachectic milieu, C/EBPβ expression remains elevated, despite activation to differentiate, resulting in the inhibition of myogenin expression and myogenesis. In vivo, cancer cachexia results in increased number of Pax7+ cells that also express C/EBPβ and the inhibition of normal repair mechanisms. Loss of C/EBPβ expression in primary myoblasts rescues differentiation under cachectic conditions without restoring myotube size, indicating that C/EBPβ is an important inhibitor of myogenesis in cancer cachexia. PMID:26709824

  8. Mutual effects of growth hormone and growth factors on avian skeletal muscle satellite cells.

    PubMed

    Hodik, V; Mett, A; Halevy, O

    1997-10-01

    Chicken growth hormone (cGH) has been shown to affect chicken skeletal muscle satellite cell proliferation and differentiation in vitro. This study describes the interactions of cGH with basic fibroblast growth factor (bFGF) and insulin-like growth factor I (IGF-I). Both cGH and bFGF induced cGH receptor (cGH-R) gene expression as well as that of the avian FGF receptor, FREK, when added at low concentrations to satellite cells. bFGF caused a rapid induction of cGH-R mRNA. Combinations of low levels of bFGF and cGH caused a further increase in receptor mRNA expression levels, relative to that caused by each peptide alone, and their effect on DNA synthesis was synergistic. However, combinations of cGH and bFGF at high concentrations decreased cGH-R and FREK mRNA levels and DNA synthesis in a dose-dependent manner. These results imply that the mutual effects of bFGF and cGH on satellite cell proliferation are receptor-mediated and that each peptide regulates both receptors gene expression. IGF-I induced DNA synthesis in satellite cells but did not affect cGH-R gene expression at any of the concentrations tested. Coincubation of 3.5 ng/ml cGH and various concentrations of IGF-I did not significantly change DNA synthesis relative to the effect of cGH alone. However, combinations with high levels of cGH abolished it. Similar time-course (up to 6 hr) induction of DNA synthesis in serum-starved cells was observed in the presence of cGH or IGF-I, suggesting that cGH affects satellite cell proliferation in an IGF-I-independent manner.

  9. Inadequate satellite cell replication compromises muscle regrowth following postnatal nutrient restriction

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Perinatal growth impairment permanently compromises skeletal muscle mass. The present study assessed the contribution of muscle satellite cell replicative capacity to this deficit. Mouse dams were fed either a low protein (LP, n=7) or control (C, n=6) diet during lactation. Pups were weaned at 21 d ...

  10. FOXP3+ T Cells Recruited to Sites of Sterile Skeletal Muscle Injury Regulate the Fate of Satellite Cells and Guide Effective Tissue Regeneration

    PubMed Central

    Castiglioni, Alessandra; Basso, Veronica; Vezzoli, Michela; Monno, Antonella; Almada, Albert E.; Mondino, Anna; Wagers, Amy J.; Manfredi, Angelo A.; Rovere-Querini, Patrizia

    2015-01-01

    Muscle injury induces a classical inflammatory response in which cells of the innate immune system rapidly invade the tissue. Macrophages are prominently involved in this response and required for proper healing, as they are known to be important for clearing cellular debris and supporting satellite cell differentiation. Here, we sought to assess the role of the adaptive immune system in muscle regeneration after acute damage. We show that T lymphocytes are transiently recruited into the muscle after damage and appear to exert a pro-myogenic effect on muscle repair. We observed a decrease in the cross-sectional area of regenerating myofibers after injury in Rag2-/- γ-chain-/- mice, as compared to WT controls, suggesting that T cell recruitment promotes muscle regeneration. Skeletal muscle infiltrating T lymphocytes were enriched in CD4+CD25+FOXP3+ cells. Direct exposure of muscle satellite cells to in vitro induced Treg cells effectively enhanced their expansion, and concurrently inhibited their myogenic differentiation. In vivo, the recruitment of Tregs to acutely injured muscle was limited to the time period of satellite expansion, with possibly important implications for situations in which inflammatory conditions persist, such as muscular dystrophies and inflammatory myopathies. We conclude that the adaptive immune system, in particular T regulatory cells, is critically involved in effective skeletal muscle regeneration. Thus, in addition to their well-established role as regulators of the immune/inflammatory response, T regulatory cells also regulate the activity of skeletal muscle precursor cells, and are instrumental for the proper regeneration of this tissue. PMID:26039259

  11. FOXP3+ T Cells Recruited to Sites of Sterile Skeletal Muscle Injury Regulate the Fate of Satellite Cells and Guide Effective Tissue Regeneration.

    PubMed

    Castiglioni, Alessandra; Corna, Gianfranca; Rigamonti, Elena; Basso, Veronica; Vezzoli, Michela; Monno, Antonella; Almada, Albert E; Mondino, Anna; Wagers, Amy J; Manfredi, Angelo A; Rovere-Querini, Patrizia

    2015-01-01

    Muscle injury induces a classical inflammatory response in which cells of the innate immune system rapidly invade the tissue. Macrophages are prominently involved in this response and required for proper healing, as they are known to be important for clearing cellular debris and supporting satellite cell differentiation. Here, we sought to assess the role of the adaptive immune system in muscle regeneration after acute damage. We show that T lymphocytes are transiently recruited into the muscle after damage and appear to exert a pro-myogenic effect on muscle repair. We observed a decrease in the cross-sectional area of regenerating myofibers after injury in Rag2-/- γ-chain-/- mice, as compared to WT controls, suggesting that T cell recruitment promotes muscle regeneration. Skeletal muscle infiltrating T lymphocytes were enriched in CD4+CD25+FOXP3+ cells. Direct exposure of muscle satellite cells to in vitro induced Treg cells effectively enhanced their expansion, and concurrently inhibited their myogenic differentiation. In vivo, the recruitment of Tregs to acutely injured muscle was limited to the time period of satellite expansion, with possibly important implications for situations in which inflammatory conditions persist, such as muscular dystrophies and inflammatory myopathies. We conclude that the adaptive immune system, in particular T regulatory cells, is critically involved in effective skeletal muscle regeneration. Thus, in addition to their well-established role as regulators of the immune/inflammatory response, T regulatory cells also regulate the activity of skeletal muscle precursor cells, and are instrumental for the proper regeneration of this tissue.

  12. Smad4 restricts differentiation to promote expansion of satellite cell derived progenitors during skeletal muscle regeneration

    PubMed Central

    Paris, Nicole D; Soroka, Andrew; Klose, Alanna; Liu, Wenxuan; Chakkalakal, Joe V

    2016-01-01

    Skeletal muscle regenerative potential declines with age, in part due to deficiencies in resident stem cells (satellite cells, SCs) and derived myogenic progenitors (MPs); however, the factors responsible for this decline remain obscure. TGFβ superfamily signaling is an inhibitor of myogenic differentiation, with elevated activity in aged skeletal muscle. Surprisingly, we find reduced expression of Smad4, the downstream cofactor for canonical TGFβ superfamily signaling, and the target Id1 in aged SCs and MPs during regeneration. Specific deletion of Smad4 in adult mouse SCs led to increased propensity for terminal myogenic commitment connected to impaired proliferative potential. Furthermore, SC-specific Smad4 disruption compromised adult skeletal muscle regeneration. Finally, loss of Smad4 in aged SCs did not promote aged skeletal muscle regeneration. Therefore, SC-specific reduction of Smad4 is a feature of aged regenerating skeletal muscle and Smad4 is a critical regulator of SC and MP amplification during skeletal muscle regeneration. DOI: http://dx.doi.org/10.7554/eLife.19484.001 PMID:27855784

  13. S-adenosylmethionine stimulates fatty acid metabolism-linked gene expression in porcine muscle satellite cells.

    PubMed

    Yue, Tao; Fang, Qian; Yin, JingDong; Li, DeFa; Li, Wei

    2010-10-01

    Evidence indicates that both S-adenosylmethionine (SAMe) metabolism and intramuscular fat are associated with insulin resistance and type II diabetes. However, it is still unknown whether SAMe have effects on intramuscular adipogenesis. The present study investigated the roles of SAMe in the adipogenic differentiation of porcine muscle satellite cells. Cells isolated from neonatal pig muscle were treated with different concentrations of SAMe (0, 0.5 and 1.0 mM) for 24 h, induced for a 9-day adipogenic differentiation and were finally stained by oil red O staining. The adipocyte determination and differentiation factor-1 (ADD1) and peroxisome proliferator-activated receptor gamma (PPARγ) mRNA and protein were stimulated by SAMe treatment in a dose-dependent manner. Lipoprotein lipase (LPL) mRNA and protein were enhanced in 1.0 mM treatment group, compared with the control. No significant difference was observed in the intracellular lipid content among treatments. These results provide evidence that SAMe may be associated with intramuscular adipogenesis and indicate a novel action of SAMe in fat metabolism.

  14. Age-associated NF-κB signaling in myofibers alters the satellite cell niche and re-strains muscle stem cell function

    PubMed Central

    Tan, Kah Yong; Rosner, Bernard; Dreyfuss, Jonathan M.; Gjata, Ornela; Tran, Peter; Shoelson, Steven E.; Wagers, Amy J.

    2016-01-01

    Skeletal muscle is a highly regenerative tissue, but muscle repair potential is increasingly compromised with advancing age. In this study, we demonstrate that increased NF-κB activity in aged muscle fibers contributes to diminished myogenic potential of their associated satellite cells. We further examine the impact of genetic modulation of NF-κB signaling in muscle satellite cells or myofibers on recovery after damage. These studies reveal that NF-κB activity in differentiated myofibers is sufficient to drive dysfunction of muscle regenerative cells via cell-non-autonomous mechanisms. Inhibition of NF-κB, or its downstream target Phospholipase A2, in myofibers rescued muscle regenerative potential in aged muscle. Moreover, systemic administration of sodium salicylate, an FDA-approved NF-κB inhibitor, decreased inflammatory gene expression and improved repair in aged muscle. Together, these studies identify a unique NF-κB regulated, non-cell autonomous mechanism by which stem cell function is linked to lipid signaling and homeostasis, and provide important new targets to stimulate muscle repair in aged individuals. PMID:27852976

  15. Near Term Effects from Satellite Break-Ups on Manned Space Activities

    NASA Technical Reports Server (NTRS)

    Theall, J. R.; Matney, M. J.

    2000-01-01

    Since 1961, almost 160 satellite break-ups have occurred on-orbit, and have been the major contributor to the growth of the orbital debris population. When a satellite breaks up, the debris exists in a relatively concentrated form, orbiting in a loose cloud with the parent body until orbital perturbations disperse the cloud into the average background. Manned space activities, which usually take place in low Earth orbit at altitudes less than 500 km, have been continuous for the past I I years while Mir was inhabited and promise to be again continuous when the International Space Station becomes permanently manned. This paper surveys historical breakups over the last I I years to determine the number that affect altitudes lower than 500 km. Selected breakup are analyzed using NASA's Satellite Breakup Risk Assessment Model (SBRAM) to determine the specific short term risk from those breakups to manned missions.

  16. Alkaline regenerative fuel cell energy storage system for manned orbital satellites

    NASA Technical Reports Server (NTRS)

    Martin, R. E.; Gitlow, B.; Sheibley, D. W.

    1982-01-01

    It is pointed out that the alkaline regenerative fuel cell system represents a highly efficient, lightweight, reliable approach for providing energy storage in an orbiting satellite. In addition to its energy storage function, the system can supply hydrogen and oxygen for attitude control of the satellite and for life support. A summary is presented of the results to date obtained in connection with the NASA-sponsored fuel cell technology advancement program, giving particular attention to the requirements of the alkaline regenerative fuel cell and the low-earth mission. Attention is given to system design guidelines, weight considerations, gold-platinum cathode cell performance, matrix development, the electrolyte reservoir plate, and the cyclical load profile tests.

  17. Dnmt3a Regulates Proliferation of Muscle Satellite Cells via p57Kip2

    PubMed Central

    Naito, Masashi; Mori, Masaki; Inagawa, Masayo; Miyata, Kohei; Hashimoto, Naohiro; Tanaka, Sakae; Asahara, Hiroshi

    2016-01-01

    Cell differentiation status is defined by the gene expression profile, which is coordinately controlled by epigenetic mechanisms. Cell type-specific DNA methylation patterns are established by chromatin modifiers including de novo DNA methyltransferases, such as Dnmt3a and Dnmt3b. Since the discovery of the myogenic master gene MyoD, myogenic differentiation has been utilized as a model system to study tissue differentiation. Although knowledge about myogenic gene networks is accumulating, there is only a limited understanding of how DNA methylation controls the myogenic gene program. With an aim to elucidate the role of DNA methylation in muscle development and regeneration, we investigate the consequences of mutating Dnmt3a in muscle precursor cells in mice. Pax3 promoter-driven Dnmt3a-conditional knockout (cKO) mice exhibit decreased organ mass in the skeletal muscles, and attenuated regeneration after cardiotoxin-induced muscle injury. In addition, Dnmt3a-null satellite cells (SCs) exhibit a striking loss of proliferation in culture. Transcriptome analysis reveals dysregulated expression of p57Kip2, a member of the Cip/Kip family of cyclin-dependent kinase inhibitors (CDKIs), in the Dnmt3a-KO SCs. Moreover, RNAi-mediated depletion of p57Kip2 replenishes the proliferation activity of the SCs, thus establishing a role for the Dnmt3a-p57Kip2 axis in the regulation of SC proliferation. Consistent with these findings, Dnmt3a-cKO muscles exhibit fewer Pax7+ SCs, which show increased expression of p57Kip2 protein. Thus, Dnmt3a is found to maintain muscle homeostasis by epigenetically regulating the proliferation of SCs through p57Kip2. PMID:27415617

  18. The differential proliferative ability of satellite cells in Lantang and Landrace pigs.

    PubMed

    Wang, Xiu-qi; Yang, Wei-jun; Yang, Zhou; Shu, Gang; Wang, Song-bo; Jiang, Qing-yan; Yuan, Li; Wu, Tong-shan

    2012-01-01

    Here, for the first time, we evaluate the hypothesis that the proliferative abilities of satellite cells (SCs) isolated from Lantang (indigenous Chinese pigs) and Landrace pigs, which differ in muscle characteristics, are different. SCs were isolated from the longissimus dorsi muscle of neonatal Lantang and Landrace pigs. Proliferative ability was estimated by the count and proliferative activity of viable cells using a hemocytometer and MTT assay at different time points after seeding, respectively. Cell cycle information was detected by flow cytometry. Results showed that there was a greater (P<0.05) number of SCs in Lantang pigs compared with Landrace pigs after 72 h of culture. The percentage of cell population in S phase and G(2)/M phases in Lantang pigs were higher (P<0.05), while in G(0)/G(1) phase was lower (P<0.05) in comparison with the Landrace pigs. The mRNA abundances of MyoD, Myf5, myogenin and Pax7 in SCs from Lantang pigs were higher (P<0.05), while those of myostatin, Smad3 and genes in the mammalian target of rapamycin (mTOR) pathway (with the exception of 4EBP1) were lower (P<0.05) than the Landrace pigs. Protein levels of MyoD, myogenin, myostatin, S6K, phosphorylated mTOR and phosphorylated eIF4E were consistent with the corresponding mRNA abundance. Collectively, these findings suggested that SCs in the two breeds present different proliferative abilities, and the proliferative potential of SCs in Lantang pigs is higher than in Landrace pigs.

  19. Comparison of growth characteristics between skeletal muscle satellite cell lines from diploid and triploid olive flounder Paralichthys olivaceus

    PubMed Central

    Wu, Zhi-hao; Tan, Xungang; Jiao, Shuang; Zhang, Pei-jun

    2016-01-01

    Objectives. According to myosatellite cell lines (MSCs) established in vitro from diploid and triploid flounder, we compared the characters of growth and differentiation of their MSCs. The results would be useful for learning the muscle development mechanism in teleosts. Materials and Methods. The skeletal muscle cells from the diploid and triploid olive flounder Paralichthys olivaceus were isolated and cultured in vitro, respectively, and the cells were characterized at the morphology and molecular level; meanwhile, the performance of these cells’ proliferation and differentiation were analyzed. Results. Two new skeletal muscle cell lines (POMSCS(2n) and POMSCS(3n)) from diploid and triploid flounder have been respectively subcultured for 67 times and 66 times. The cultured cells were mostly spindle-like mononuclear cells. They have normal flounder diploid karyotype (2n=48t) and triploid karyotype (3n=72t), respectively. Muscle satellite cell gene marker (pax7b) and myogenic cell protein marker (Desmin) were all expressed in cells of two cell lines. Both of the cells could differentiate into the large polynucleated muscle fibre cells, and immunofluorescence reactions of myosin heavy chain (MyHC) were positive. There were more cells of POMSCS(3n) to differentiate into the muscle fibre cells than that of POMSCS(2n). However, POMSCS(2n) cells proliferated more rapidly than those of POMSCS(3n) (P < 0.05). The significant fluorescent signals were observed in both POMSCS(2n) and POMSCS(3n) cells after transfected with pEGFP-N3 reporter plasmid. Conclusions. The two cell lines have been established and characterized as MSCs. We suppose that it might be the differentiation capacity, rather than the proliferation activity of MSCs to play a key role in the better growth of triploid ones than diploid. Both cell lines will become the ideal tools to learn the mechanism of fish MSCs proliferation, differentiation and regeneration during muscle development in the future. PMID

  20. Myelinating satellite oligodendrocytes are integrated in a glial syncytium constraining neuronal high-frequency activity

    PubMed Central

    Battefeld, Arne; Klooster, Jan; Kole, Maarten H. P.

    2016-01-01

    Satellite oligodendrocytes (s-OLs) are closely apposed to the soma of neocortical layer 5 pyramidal neurons but their properties and functional roles remain unresolved. Here we show that s-OLs form compact myelin and action potentials of the host neuron evoke precisely timed Ba2+-sensitive K+ inward rectifying (Kir) currents in the s-OL. Unexpectedly, the glial K+ inward current does not require oligodendrocytic Kir4.1. Action potential-evoked Kir currents are in part mediated by gap–junction coupling with neighbouring OLs and astrocytes that form a syncytium around the pyramidal cell body. Computational modelling predicts that glial Kir constrains the perisomatic [K+]o increase most importantly during high-frequency action potentials. Consistent with these predictions neurons with s-OLs showed a reduced probability for action potential burst firing during [K+]o elevations. These data suggest that s-OLs are integrated into a glial syncytium for the millisecond rapid K+ uptake limiting activity-dependent [K+]o increase in the perisomatic neuron domain. PMID:27161034

  1. Impaired metabolism of senescent muscle satellite cells is associated with oxidative modifications of glycolytic enzymes.

    PubMed

    Baraibar, Martin; Hyzewicz, Janek; Rogowska-Wrzesinska, Adelina; Bulteau, Anne-Laure; Prip-Buus, Carina; Butler-Browne, Gillian; Friguet, Bertrand

    2014-10-01

    Accumulation of damaged macromolecules, including irreversibly oxidized proteins, is a hallmark of cellular and organismal ageing. Failure of protein homesotasis is a major contributor to the age-related accumulation of damaged proteins. In skeletal muscle, tissue maintenance and regeneration is assured by resident adult stem cells known as satellite cells. During senescence their replication and differentiation is compromised contributing to sarcopenia. In this study we have addressed the impact of oxidatively modified proteins in the impaired metabolism of senescent human satellite cells. By using a targeted proteomics analysis we have found that proteins involved in protein quality control and glycolytic enzymes are the main targets of oxidation (carbonylation) and modification with advanced glycation/lipid peroxidation end products during replicative senescence of satellite cells. Inactivation of the proteasome in aged cells appeared as a key contributor to the accumulation of such damaged proteins. Untargeted metabolomic profiling and functional analyses indicated glucose metabolism impairment in senescent cells, although mitochondrial respiration remained unaffected. A metabolic shift leading to increased mobilization of non-carbohydrate substrates as branched chain amino acids or long chain fatty acids was observed in senescent cells. In addition, phospho-and glycerolipids metabolism was altered. Increased levels of acyl-carnitines indicated augmented turnover of storage and membrane lipids for energy production. Such changes reflect alterations in membrane composition and dysregulation of sphingolipids signaling during senescence. This study establishes a new concept connecting oxidative protein modifications with the altered cellular metabolism associated with the senescent phenotype. In addition, these findings highlight the molecular mechanisms implicated in satellite cells dysfunction during ageing, paving the road for future therapeutic interventions

  2. Bacterial activation of mast cells.

    PubMed

    Chi, David S; Walker, Elaine S; Hossler, Fred E; Krishnaswamy, Guha

    2006-01-01

    Mast cells often are found in a perivascular location but especially in mucosae, where they may response to various stimuli. They typically associate with immediate hypersensitive responses and are likely to play a critical role in host defense. In this chapter, a common airway pathogen, Moraxella catarrhalis, and a commensal bacterium, Neiserria cinerea, are used to illustrate activation of human mast cells. A human mast cell line (HMC-1) derived from a patient with mast cell leukemia was activated with varying concentrations of heat-killed bacteria. Active aggregation of bacteria over mast cell surfaces was detected by scanning electron microscopy. The activation of mast cells was analyzed by nuclear factor-kappaB (NF-kappaB) activation and cytokine production in culture supernatants. Both M. catarrhalis and N. cinerea induce mast cell activation and the secretion of two key inflammatory cytokines, interleukin-6 and MCP-1. This is accompanied by NF-kappaB activation. Direct bacterial contact with mast cells appears to be essential for this activation because neither cell-free bacterial supernatants nor bacterial lipopolysaccharide induce cytokine secretion.

  3. Satellite cell response to erythropoietin treatment and endurance training in healthy young men

    PubMed Central

    Hoedt, Andrea; Christensen, Britt; Nellemann, Birgitte; Mikkelsen, Ulla Ramer; Hansen, Mette; Schjerling, Peter

    2016-01-01

    Key point Erythropoietin (Epo) treatment may induce myogenic differentiation factor (MyoD) expression and prevent apoptosis in satellite cells (SCs) in murine and in vitro models.Endurance training stimulates SC proliferation in vivo in murine and human skeletal muscle.In the present study, we show, in human skeletal muscle, that treatment with an Epo‐stimulating agent (darbepoetin‐α) in vivo increases the content of MyoD+ SCs in healthy young men. Moreover, we report that Epo receptor mRNA is expressed in adult human SCs, suggesting that Epo may directly target SCs through ligand‐receptor interaction.Moreover, endurance training, but not Epo treatment, increases the SC content in type II myofibres, as well as the content of MyoD+ SCs.Collectively, our results suggest that Epo treatment can regulate human SCs in vivo, supported by Epo receptor mRNA expression in human SCs. In effect, long‐term Epo treatment during disease conditions involving anaemia may impact SCs and warrants further investigation. Abstract Satellite cell (SC) proliferation is observed following erythropoitin treatment in vitro in murine myoblasts and endurance training in vivo in human skeletal muscle. The present study aimed to investigate the effects of prolonged erythropoiesis‐stimulating agent (ESA; darbepoetin‐α) treatment and endurance training, separately and combined, on SC quantity and commitment in human skeletal muscle. Thirty‐five healthy, untrained men were randomized into four groups: sedentary‐placebo (SP, n = 9), sedentary‐ESA (SE, n = 9), training‐placebo (TP, n = 9) or training‐ESA (TE, n = 8). ESA/placebo was injected once weekly and training consisted of ergometer cycling three times a week for 10 weeks. Prior to and following the intervention period, blood samples and muscle biopsies were obtained and maximal oxygen uptake (V˙O2, max ) was measured. Immunohistochemical analyses were used to quantify fibre type specific SCs (Pax7+), myonuclei

  4. Efficient single muscle fiber isolation from alcohol-fixed adult muscle following β-galactosidase staining for satellite cell detection.

    PubMed

    Verma, Mayank; Asakura, Atsushi

    2011-01-01

    Staining for β-galactosidase activity for whole tissues, sections, and cells is a common method to detect expression of β-galactosidase reporter transgene as well as senescence-dependent β-galactosidase activity. Choice of fixatives is a critical step for detection of β-galactosidase activity, subsequent immunostaining, and enzymatic digestion of tissue to dissociate cells. In this report, the authors examined several aldehyde and alcohol fixatives in mouse skeletal muscle tissues for their efficiency at improving detection of β-galactosidase activity as well as detection by immunostaining. In addition, fixatives were also analyzed for their efficiency for collagenase digestion to isolate single muscle fibers on postfixed β-galactosidase-stained whole skeletal muscle tissues. The results show that fixing cells with isopropanol yields the greatest reliability and intensity in both β-galactosidase staining as well as double staining for β-galactosidase activity and antibodies. In addition, isopropanol and ethanol, but not glutaraldehyde or paraformaldehyde, allow for the isolation of single muscle fibers from the diaphragm and tibialis anterior muscles following postfixed β-galactosidase staining. Using this method, it is possible to identify the amount of cells that occupy the satellite cell compartment in single muscle fibers prepared from any muscle tissues, including tibialis anterior muscle and diaphragm.

  5. Knowledge Management Activity within the Satellite Domain in Japan Aerospace Exploration Agency

    NASA Astrophysics Data System (ADS)

    Tateshita, Hiroaki; Soga, Midori; Fukuda, Takao; Miyoshi, Hiroshi

    Previously, each satellite project in JAXA had individually its own way of managing technical information (e.g. technical documents for planning, requirements, specifications, design, test, and operation). Although there was an information sharing environment in JAXA, no project actively submitted its own information due to a lack of functions for access control and for rapid acquisition of information, which are required by satellite projects. These situations made it very difficult for users to gather information on other projects. Additionally, there was the risk of losing significant knowledge of satellite projects upon their termination. In order to resolve these issues, minimum standard rules, including user-friendly classification rules, were established from the point of view of leveraging knowledge through long discussions with each project. An information system with appropriate access control was developed to implement the standard rules. Since April 2007, the rules and the system have been applied to each project. The risk of losing knowledge has been reduced by enabling the terminated projects to smoothly transfer their technical information to the system. This paper presents an overview of our current knowledge-management activity within the satellite domain including the remaining issues and the proposed solutions to these issues.

  6. A cell-autonomous defect in skeletal muscle satellite cells expressing low levels of survival of motor neuron protein.

    PubMed

    Hayhurst, Monica; Wagner, Amanda K; Cerletti, Massimiliano; Wagers, Amy J; Rubin, Lee L

    2012-08-15

    Mutations in the Survival of Motor Neuron (SMN) gene underlie the development of spinal muscular atrophy (SMA), which currently represents the leading genetic cause of mortality in infants and toddlers. SMA is characterized by degeneration of spinal cord motor neurons and muscle atrophy. Although SMA is often considered to be a motor neuron disease, accumulating evidence suggests that muscle cells themselves may be affected by low levels of SMN. Here, we examine satellite cells, tissue-resident stem cells that play an essential role in the growth and repair of skeletal muscle, isolated from a severe SMA mouse model (Smn(-/-); SMN2(+/+)). We found similar numbers of satellite cells in the muscles of SMA and wild-type (Smn(+/+); SMN2(+/+)) mice at postnatal day 2 (P2), and, when isolated from skeletal muscle using cell surface marker expression, these cells showed comparable survival and proliferative potential. However, SMA satellite cells differentiate abnormally, revealed by the premature expression of muscle differentiation markers, and, especially, by a reduced efficiency in forming myotubes. These phenotypes suggest a critical role of SMN protein in the intrinsic regulation of muscle differentiation and suggest that abnormal muscle development contributes to the manifestation of SMA symptoms.

  7. Early-age heat exposure affects skeletal muscle satellite cell proliferation and differentiation in chicks.

    PubMed

    Halevy, O; Krispin, A; Leshem, Y; McMurtry, J P; Yahav, S

    2001-07-01

    Exposure of young chicks to thermal conditioning (TC; i.e., 37 degrees C for 24 h) resulted in significantly improved body and muscle growth at a later age. We hypothesized that TC causes an increase in satellite cell proliferation, necessary for further muscle hypertrophy. An immediate increase was observed in satellite cell DNA synthesis in culture and in vivo in response to TC of 3-day-old chicks to levels that were significantly higher than those of control chicks. This was accompanied by a marked induction of insulin-like growth factor-I (IFG-I), but not hepatocyte growth factor in the breast muscle. No significant difference between treatments in plasma IGF-I levels was observed. A marked elevation in muscle regulatory factors on day 5, followed by a decline in cell proliferation on day 6 together with continuous high levels of IGF-I in the TC chick muscle may indicate accelerated cell differentiation. These data suggest a central role for IGF-I in the immediate stimulation of satellite cell myogenic processes in response to heat exposure.

  8. Early posthatch feeding stimulates satellite cell proliferation and skeletal muscle growth in turkey poults.

    PubMed

    Halevy, Orna; Nadel, Yael; Barak, Miriam; Rozenboim, Israel; Sklan, David

    2003-05-01

    The effect of early posthatch feeding on skeletal muscle growth and satellite cell myogenesis was studied in turkey poults. Poults were either fed immediately posthatch or food-deprived for the first 48 h and then refed for the rest of the experiment. Body and breast muscle weights were lower in the starved poults than in fed controls throughout the experiment (P < 0.05). Cultures of breast muscle satellite cells revealed significantly higher DNA synthesis in the fed group than in the starved group as early as d 1 (P < 0.05). These levels continued to rise, reaching approximately 500-fold those of feed-deprived poults on d 4. In the latter group, thymidine incorporation peaked only on d 6, and then declined. Thereafter, it decreased to the same levels as those in the fed group. Satellite cell number per gram muscle increased until d 4, and was higher in the fed group than in the starved group (P < 0.05). Pax7 levels in cell cultures derived from the fed group were markedly higher than in the starved group on d 2 (P < 0.05). Myogenin levels in both culture and muscle were higher in the fed than in the starved groups until d 4 (P < 0.05). Phosphorylation of the survival factor Akt and cyclin-dependent kinase inhibitor p21 levels were higher in cells derived from the fed group relative to those from the starved group 48 h posthatch (P < 0.05). Similarly, Akt phosphorylation and insulin-like growth factor I (IGF-I) levels were significantly higher in the muscles of the fed group (P < 0.05). Together, these results suggest that immediate posthatch feeding of poults is critical for satellite cell survival and myogenesis probably via IGF-I.

  9. Pico Satellite Solar Cell Testbed (PSSC Testbed) Design

    DTIC Science & Technology

    2007-09-30

    addition, there are two reaction wheels , which are aligned along the long axis of the spacecraft. One reaction wheel will be spun up using power from the...launch vehicle before ejection from the Picosatellite launcher. After ejection from the Picosatellite launcher, the reaction wheel will spin down and... reaction wheel will be spun up to reduce the spin rate of the PSSC Testbed to 2 RPM to make meas- urements of the solar cell current-voltage

  10. Imprinted Genes and Satellite Loci Are Differentially Methylated in Bovine Somatic Cell Nuclear Transfer Clones

    PubMed Central

    Shen, Chih-Jie; Lin, Chiao-Chieh; Shen, Perng-Chih; Cheng, Winston T.K.; Chen, Hsiao-Ling; Chang, Tsung-Chou; Liu, Shyh-Shyan

    2013-01-01

    Abstract In mammals, genome-wide epigenetic reprogramming systems exist in primordial germ cells and zygotes. These reprogramming systems play crucial roles in regulating genome functions during critical stages of embryonic development, and they confer the stability of gene expression during mammalian development. The frequent unexpected loss of progeny from somatic cell nuclear transfer (SCNT) is an ongoing problem. In this study, we used six cloned bovines (named NT-1 to NT-6), which were created by ear fibroblast nuclear transfer and displayed short life spans with multiple organ defects, as an experimental model. We focus here on three imprinted genes (IGF2, H19, and XIST) and four satellite loci (Satellite I, Satellite II, Art2, and VNTR) to investigate their methylation changes. The results revealed that aberrant methylation frequently occurred in the analyzed imprinted genes, but not in the satellite loci, of the cloned bovines. After the bovine fibroblast cells were treated with the 5-aza-2(′)-deoxycytidine (5-Aza-dc) demethylation agent, the methylation percentages of the XIST and H19 putative differentially methylated region (DMR) were significantly decreased (XIST, p<0.01; H19, p<0.05) followed by an increase in their mRNA expression levels (p<0.01). Furthermore, we found that five short-lived cloned bovines (NT-1 to NT-5) exhibited more severe aberrant methylation changes in the three imprinted genes examined than the little longer-lived clone (NT-6) compared with wild-type (WT) cows. Our data suggest that the reprogramming of the methylation-controlled regions between the imprinted genes and satellite loci are differences and may be involved with additional mechanisms that need further elucidation. PMID:23961768

  11. Sorting single satellite cells from individual myofibers reveals heterogeneity in cell-surface markers and myogenic capacity.

    PubMed

    Chapman, Matthew R; Balakrishnan, Karthik R; Li, Ju; Conboy, Michael J; Huang, Haiyan; Mohanty, Swomitra K; Jabart, Eric; Hack, James; Conboy, Irina M; Sohn, Lydia L

    2013-04-01

    Traditional cell-screening techniques such as FACS and MACS are better suited for large numbers of cells isolated from bulk tissue and cannot easily screen stem or progenitor cells from minute populations found in their physiological niches. Furthermore, these techniques rely upon irreversible antibody binding, potentially altering cell properties, including gene expression and regenerative capacity. To address these challenges, we have developed a novel, label-free stem-cell analysis and sorting platform capable of quantifying cell-surface marker expression of single functional organ stem cells directly isolated from their micro-anatomical niche. Using our unique platform, we have discovered a remarkable heterogeneity in both the regenerative capacity and expression of CXCR4, β1-integrin, Sca-1, M-cadherin, Syndecan-4, and Notch-1 in freshly isolated muscle stem (satellite) cells residing on different, single myofibers and have identified a small population of Sca-1(+)/Myf5(+) myogenic satellite cells. Our results demonstrate the utility of our single-cell platform for uncovering and functionally characterizing stem-cell heterogeneity in the organ microniche.

  12. Regulation of turkey myogenic satellite cell migration by MicroRNAs miR-128 and miR-24.

    PubMed

    Velleman, S G; Harding, R L

    2016-12-05

    Myogenic satellite cells are an adult stem cell responsible for all post-hatch muscle growth in poultry. As a stem cell population, satellite cells are highly heterogeneous, but the origin of this heterogeneity remains unclear. Heterogeneity is, in part, regulated by gene expression. One method of endogenous gene regulation that may contribute to heterogeneity is microRNAs (miRNAs). Two miRNAs previously shown to regulate poultry myogenic satellite cell proliferation and differentiation, miR-128 and miR-24, were studied to determine if they also affected satellite cell migration. Satellite cell migration is an essential step for both proliferation and differentiation. During proliferation, satellite cells will migrate and align to form new myofibers or donate their nuclei to existing myofibers leading to muscle fiber hypertrophy or regeneration. Transient transfection of miRNA specific mimics to each miRNA reduced migration of satellite cells following a cell culture scratch at 72 h of proliferation when the cultures were 90 to 100% confluent. However, only the migration in cells transfected with miR-24 mimics at 24 and 30 h following the scratch was significantly reduced (P ≤ 0.05) to around 70% of the distance migrated by controls. Alternately, transfection with inhibitors specific to miR-128 or miR-24 significantly (P ≤ 0.05) increased migration between 147 and 252% compared to their controls between 24 and 48 h following the scratch. These data demonstrate that miR-128 and miR-24 play a role in myogenic satellite cell migration, which will impact muscle development and growth.

  13. Observations in the thermal IR and visible of a retired satellite in the graveyard orbit, and comparisons to active satellites in GEO

    NASA Astrophysics Data System (ADS)

    Skinner, Mark A.; Russell, Ray W.; Kelecy, Tom; Gregory, Steve; Rudy, Richard J.; Kim, Daryl L.; Crawford, Kirk

    2014-12-01

    There exists a population of defunct satellites in the geo-stationary arc that potentially pose a hazard to current and future operational satellites. These drifting, non-station-kept objects have a variety of ages and sizes, and many are trapped in libration orbits around the Earth's two gravitational potential wells (the non-spherical nature of the Earth gives rise to two geo-potential wells or "stable points" that affect objects in geostationary and geosynchronous orbits), whereas others were boosted to higher altitudes into so-called "graveyard" orbits. We have observed several of the approximately 49 objects in libration orbits about the Western stable point (R. Choc, T. Flohrer, and B. Bastida, "Classification of Geosynchronous Objects," Issue 13, ESA/ESOC, February 2011), as well as objects in graveyard orbits. We have carried out an observational campaign utilizing The Aerospace Corporation's 3-13 μm Broadband Array Spectrograph System (BASS), as well as with several optical sensors to collect data on a representative sample of these objects at a variety of solar phase angles. Here we report on recent BASS observations of a retired satellite in the "graveyard" orbit, and compare them with data we had collected over six years ago, while the satellite was still active. Data are also presented on similar satellites that are still active. We describe our methods, the data collected, our results, and our future plans.

  14. Plasticity and recovery of skeletal muscle satellite cells during limb regeneration.

    PubMed

    Morrison, Jamie I; Borg, Paula; Simon, András

    2010-03-01

    Salamander limb regeneration depends on local progenitors whose progeny are recruited to the new limb. We previously identified a Pax7(+) cell population in skeletal muscle whose progeny have the potential to contribute to the regenerating limb. However, the plasticity of individual Pax7(+) cells, as well as their recovery within the new limb, was unclear. Here, we show that Pax7(+) cells remain present after multiple rounds of limb amputation/regeneration. Pax7(+) cells are found exclusively within skeletal muscle in the regenerating limb and proliferate where the myofibers are growing. Pax7 is rapidly down-regulated in the blastema, and analyses of clonal derivatives show that Pax7(+) cell progeny are not restricted to skeletal muscle during limb regeneration. Our data suggest that the newt regeneration blastema is not entirely a composite of lineage-restricted progenitors. The results demonstrate that except for a transient and subsequently blunted increase, skeletal muscle satellite cells constitute a stable pool of reserve cells for multiple limb regeneration events.-Morrison, J. I., Borg, P., Simon, A. Plasticity and recovery of skeletal muscle satellite cells during limb regeneration.

  15. Satellite DNA sequences flank amplified DHFR domains in marker chromosomes of mouse fibrosarcoma cells.

    PubMed

    Riva, P; Orlando, S; Labella, T; Larizza, L

    1994-01-01

    This study centers on marker chromosomes carrying expanded chromosomal regions which were observed in two independent derivatives of the AA12 murine fibrosarcoma line, the 10(-3) M MTX-res H2 and the 5 x 10(-7) M MTX-res E. Previous characterization of the marker chromosomes of MTX-res variants showed their common derivation from a marker chromosome (m) of the parental line, endowed with two interstitial C-bands. Cytogenetic evidence pointed to one C-band of m as the site involved in the chromosomal rearrangements leading to the HSR/ASR chromosomes. ISH of a 3H-labeled satellite DNA probe allowed satellite sequences flanking the HSR/ASR in the marker chromosomes, where the C-band was no longer visible, to be detected. FISH experiments using biotinylated DHFR and satellite DNA probes showed that the respective target sequences are contiguous in new marker chromosomes. They also allowed inter- and intrachromosomal rearrangements to be seen at DHFR amplicons and satellite sequences. Double-color FISH using digoxygenated satellite DNA and biotinylated pDHFR7 showed that in a marker chromosome from the H2 cell line the two target sequences are not only adjacent, but closer than 3 Mb, as indicated by overlapping of the different fluorescence signals given by the two probes. Another marker chromosome in the E variant was shown to display a mixed ladder structure consisting of a head-to-head tandem of irregularly-sized satellite DNA blocks, with two symmetrical interspersed DHFR clusters.

  16. Solar sail attitude control including active nutation damping in a fixed-momentum wheel satellite

    NASA Astrophysics Data System (ADS)

    Azor, Ruth

    1992-02-01

    In the geostationary cruise of a momentum biased satellite, it is necessary to stabilize the roll/yaw attitude due to disturbances caused by solar radiation pressure. This work presents a roll/yaw control system with a horizon sensor for roll measurement. Roll/yaw control is obtained by the use of solar arrays and fixed flaps as actuators. The design also includes an active nutation damping method.

  17. Significant role of μ-calpain (CANP1) in proliferation/survival of bovine skeletal muscle satellite cells.

    PubMed

    Van Ba, Hoa; Inho, Hwang

    2013-12-01

    Calpains are a family of Ca(2+)-dependent intracellular cysteine proteases, including the ubiquitously expressed μ-calpain (CANP1) and m-calpain (CANP2). The CANP1 has been found to play a central role in postmortem proteolysis and meat tenderization. However, the physiological roles of CANP1 in cattle skeletal satellite cells remain unclear. In this study, three small interference RNA sequences (siRNAs) targeting CANP1 gene were designed and ligated into pSilencer plasmid vector to construct shRNA expression constructs. Suppression of CANP1 in satellite cells was evaluated using these shRNA expressing constructs. Our results revealed that all three siRNAs could downregulate the expression of CANP1. Suppression of CANP1 significantly reduced cell viability in cell proliferation when compared with control cells. We found a crosstalk between CANP1 and caspase systems, particularly suppression of CANP1 resulted in an increase in the expressions of apoptotic caspases such as caspase-3, caspase-6, caspase-7, caspase-8, and caspase-9, as well as heat-shock protein (HSP) systems. Additionally, suppression of CANP1 led to the upregulation of other apoptosis and DNA damage-regulating genes whilst at the same time downregulating proliferation, migration, and differentiation-regulating genes. The results of our findings report for the first time that suppression of CANP1 resulted in the activation of caspase and HSP systems which might in turn regulate apoptosis through the caspase-dependent cell death pathway. This clearly demonstrates the key roles of CANP1 in regulation of cell proliferation and survival.

  18. Muscle disuse atrophy is not accompanied by changes in skeletal muscle satellite cell content.

    PubMed

    Snijders, Tim; Wall, Benjamin T; Dirks, Marlou L; Senden, Joan M G; Hartgens, Fred; Dolmans, John; Losen, Mario; Verdijk, Lex B; van Loon, Luc J C

    2014-04-01

    Muscle disuse leads to a considerable loss in skeletal muscle mass and strength. However, the cellular mechanisms underlying disuse-induced muscle fibre atrophy remain to be elucidated. Therefore we assessed the effect of muscle disuse on the CSA (cross-sectional area), muscle fibre size, satellite cell content and associated myocellular signalling pathways of the quadriceps muscle. A total of 12 healthy young (24±1 years of age) men were subjected to 2 weeks of one-legged knee immobilization via a full-leg cast. Before and immediately after the immobilization period and after 6 weeks of natural rehabilitation, muscle strength [1RM (one-repetition maximum)], muscle CSA [single slice CT (computed tomography) scan] and muscle fibre type characteristics (muscle biopsies) were assessed. Protein and/or mRNA expression of key genes [i.e. MYOD (myogenic differentiation), MYOG (myogenin) and MSTN (myostatin)] in the satellite cell regulatory pathways were determined using Western blotting and RT-PCR (real-time PCR) analyses respectively. The present study found that quadriceps CSA declined following immobilization by 8±2% (P<0.05). In agreement, both type I and type II muscle fibre size decreased 7±3% and 13±4% respectively (P<0.05). No changes were observed in satellite cell content following immobilization in either type I or type II muscle fibres. Muscle MYOG mRNA expression doubled (P<0.05), whereas MSTN protein expression decreased 30±9% (P<0.05) following immobilization. Muscle mass and strength returned to the baseline values within 6 weeks of recovery without any specific rehabilitative programme. In conclusion, 2 weeks of muscle disuse leads to considerable loss in skeletal muscle mass and strength. The loss in muscle mass was attributed to both type I and type II muscle fibre atrophy, and was not accompanied by a decline in satellite cell content.

  19. Rainbow trout (Oncorhynchus mykiss) muscle satellite cells are targets of salmonid alphavirus infection.

    PubMed

    Biacchesi, Stéphane; Jouvion, Grégory; Mérour, Emilie; Boukadiri, Abdelhak; Desdouits, Marion; Ozden, Simona; Huerre, Michel; Ceccaldi, Pierre-Emmanuel; Brémont, Michel

    2016-01-08

    Sleeping disease in rainbow trout is characterized by an abnormal swimming behaviour of the fish which stay on their side at the bottom of the tanks. This sign is due to extensive necrosis and atrophy of red skeletal muscle induced by the sleeping disease virus (SDV), also called salmonid alphavirus 2. Infections of humans with arthritogenic alphaviruses, such as Chikungunya virus (CHIKV), are global causes of debilitating musculoskeletal diseases. The mechanisms by which the virus causes these pathologies are poorly understood due to the restrictive availability of animal models capable of reproducing the full spectrum of the disease. Nevertheless, it has been shown that CHIKV exhibits a particular tropism for muscle stem cells also known as satellite cells. Thus, SDV and its host constitute a relevant model to study in details the virus-induced muscle atrophy, the pathophysiological consequences of the infection of a particular cell-type in the skeletal muscle, and the regeneration of the muscle tissue in survivors together with the possible virus persistence. To study a putative SDV tropism for that particular cell type, we established an in vivo and ex vivo rainbow trout model of SDV-induced atrophy of the skeletal muscle. This experimental model allows reproducing the full panel of clinical signs observed during a natural infection since the transmission of the virus is arthropod-borne independent. The virus tropism in the muscle tissue was studied by immunohistochemistry together with the kinetics of the muscle atrophy, and the muscle regeneration post-infection was observed. In parallel, an ex vivo model of SDV infection of rainbow trout satellite cells was developed and virus replication and persistence in that particular cell type was followed up to 73 days post-infection. These results constitute the first observation of a specific SDV tropism for the muscle satellite cells.

  20. The effects of endothelin-1 on satellite glial cells in peripheral ganglia.

    PubMed

    Feldman-Goriachnik, Rachel; Hanani, Menachem

    2017-03-18

    Endothelins (ET) are a family of highly active neuropeptides with manifold influences via ET receptors (ETR) in both the peripheral and central nervous systems. We have shown previously that satellite glial cells (SGCs) in mouse trigeminal ganglia (TG) are extremely sensitive to ET-1 in evoking [Ca(2+)]in increase, apparently via ETBR activation, but there is no functional information on ETR in SGCs of other peripheral ganglia. Here we tested the effects of ET-1 on SGCs in nodose ganglia (NG), which is sensory, and superior cervical ganglia (Sup-CG), which is part of the sympathetic nervous system, and further investigated the influence of ET-1 on SGCs in TG. Using calcium imaging we found that SGCs in intact, freshly isolated NG and Sup-CG are highly sensitive to ET-1, with threshold concentration at 0.1nM. Our results showed that [Ca(2+)]in elevation in response to ET-1 was partially due to Ca(2+) influx from the extracellular space and partially to Ca(2+) release from intracellular stores. Using receptor selective ETR agonists and antagonists, we found that the responses were mediated by mixed ETAR/ETBR in SGCs of NG and predominantly by ETBR in SGCs of Sup-CG. By employing intracellular dye injection we examined coupling among SGCs around different neurons in the presence of 5nM ET-1 and observed coupling inhibition in all the three ganglion types. In summary, our work showed that SGCs in mouse sensory and sympathetic ganglia are highly sensitive to ET-1 and that this peptide markedly reduces SGCs coupling. We conclude that ET-1, which may participate in neuron-glia communications, has similar functions in wide range of peripheral ganglia.

  1. Satellite cell ablation attenuates short-term fast-to-slow fibre type transformations in rat fast-twitch skeletal muscle.

    PubMed

    Martins, Karen J B; Murdoch, Gordon K; Shu, Yang; Harris, R Luke W; Gallo, Maria; Dixon, Walter T; Foxcroft, George R; Gordon, Tessa; Putman, Charles T

    2009-06-01

    The purpose of this time-course study was to determine whether satellite cell ablation within rat tibialis anterior (TA) muscles exposed to short-term chronic low-frequency stimulation (CLFS) would limit fast-to-slow fibre type transformations. Satellite cells of the left TA were ablated by exposure to gamma-irradiation before 1, 2, 5 or 10 days of CLFS and 1 week later where required. Control groups received only CLFS or a sham operation. Continuous infusion of 5-bromo-2'-deoxyuridine revealed that CLFS first induced an increase in satellite cell proliferation at 1 day, up to a maximum at 10 days over control (mean +/- SEM, 5.7 +/- 0.7 and 20.4 +/- 1.0 versus 1.5 +/- 0.2 mm(-2), respectively, P < 0.007) that was abolished by gamma-irradiation. Myosin heavy chain mRNA, immunohistochemical and sodium dodecyl sulfate polyacrylamide gel electrophoresis analyses revealed CLFS-induced fast-to-slow fibre type transformation began at 5 days and continued at 10 days; in those muscles that were also exposed to gamma-irradiation, attenuation occurred within the fast fibre population, and the final fast-twitch to slow-twitch adaptation did not occur. These findings indicate satellite cells play active and obligatory roles early on in the time course during skeletal muscle fibre type adaptations to CLFS.

  2. On spatial distribution of proton radiation belt from solar cell degradation of Akebono satellite

    NASA Astrophysics Data System (ADS)

    Miyake, W.; Miyoshi, Y.; Matsuoka, A.

    2013-12-01

    Solar cells on any satellite degrade gradually due to severe space radiation environment. We found a fair correlation between the decrease rate of solar cell output current of Akebono satellite orbiting in the inner magnetosphere and trapped proton flux from AP8 model between 1989 and 1992. After 1993, presumably as a result of long-term degradation, variation of solar cell output seems more susceptible to other causes such as high temperature effect, and simple monthly averaged data show no significant relation between them. One of possible causes for the temperature variation of the solar cells is terrestrial heat radiation with changing orientation of solar cell panels towards the earth and another is solar radiation varied with eccentric earth's orbit around the sun. In order to remove the possible temperature effect, we sort the data expected to be least affected by the terrestrial heat radiation from the orbit conditions, and also analyze difference of the output current for a month from that for the same month in the previous year. The analysis method leads us to successfully track a continuous correlation between the decease rate of solar cell output and energetic trapped proton flux up to 1996. We also discuss the best-fitted spatial distribution of energetic protons from comparison with model calculations.

  3. Roles of adherent myogenic cells and dynamic culture in engineered muscle function and maintenance of satellite cells.

    PubMed

    Juhas, Mark; Bursac, Nenad

    2014-11-01

    Highly functional engineered skeletal muscle constructs could serve as physiological models of muscle function and regeneration and have utility in therapeutic replacement of damaged or diseased muscle tissue. In this study, we examined the roles of different myogenic cell fractions and culturing conditions in the generation of highly functional engineered muscle. Fibrin-based muscle bundles were fabricated using either freshly-isolated myogenic cells or their adherent fraction pre-cultured for 36 h. Muscle bundles made of these cells were cultured in both static and dynamic conditions and systematically characterized with respect to early myogenic events and contractile function. Following 2 weeks of culture, we observed both individual and synergistic benefits of using the adherent cell fraction and dynamic culture on muscle formation and function. In particular, optimal culture conditions resulted in significant increase in the total cross-sectional muscle area (- 3-fold), myofiber size (- 1.6-fold), myonuclei density (- 1.2-fold), and force generation (- 9-fold) compared to traditional use of freshly-isolated cells and static culture. Curiously, we observed that only a simultaneous use of the adherent cell fraction and dynamic culture resulted in accelerated formation of differentiated myofibers which were critical for providing a niche-like environment for maintenance of a satellite cell pool early during culture. Our study identifies key parameters for engineering large-size, highly functional skeletal muscle tissues with improved ability for retention of functional satellite cells.

  4. Visual attention based detection of signs of anthropogenic activities in satellite imagery

    SciTech Connect

    Skurikhin, Alexei N

    2010-10-13

    With increasing deployment of satellite imaging systems, only a small fraction of collected data can be subject to expert scrutiny. We present and evaluate a two-tier approach to broad area search for signs of anthropogenic activities in high-resolution commercial satellite imagery. The method filters image information using semantically oriented interest points by combining Harris corner detection and spatial pyramid matching. The idea is that anthropogenic structures, such as rooftop outlines, fence corners, road junctions, are locally arranged in specific angular relations to each other. They are often oriented at approximately right angles to each other (which is known as rectilinearity relation). Detecting the rectilinearity provides an opportunity to highlight regions most likely to contain anthropogenic activity. This is followed by supervised classification of regions surrounding the detected corner points as man-made vs. natural scenes. We consider, in particular, a search for anthropogenic activities in uncluttered areas. In this paper, we proposed and evaluated a two-tier approach to broad area search for signs of anthropogenic activities. Results from experiments on high-resolution ({approx}0.6m) commercial satellite image data showed the potential applicability of this approach and its ability of achieving both high precision and recall rates. The main advantage of combining corner-based cueing with general object recognition is that the incorporation of domain specific knowledge even in its more general form, such as presence of comers, provides a useful cue to narrow the focus of search for signs of anthropogenic activities. Combination of comer based cueing with spatial pyramid matching addressed the issue of comer categorization. An important practical issue for further research is optimizing the balance between false positive and false negative rates. While the results presented in the paper are encouraging, the problem of an automated broad area

  5. MIMO active vibration control of magnetically suspended flywheels for satellite IPAC service

    NASA Astrophysics Data System (ADS)

    Park, Junyoung

    Theory and simulation results have demonstrated that four, variable speed flywheels could potentially provide the energy storage and attitude control functions of existing batteries and control moment gyros (CMGs) on a satellite. Past modeling and control algorithms were based on the assumption of rigidity in the flywheel's bearings and the satellite structure. This dissertation provides simulation results and theory which eliminates this assumption utilizing control algorithms for active vibration control (AVC), flywheel shaft levitation and integrated power transfer and attitude control (IPAC) that are effective even with low stiffness active magnetic bearings (AMB), and flexible satellite appendages. The flywheel AVC and levitation tasks are provided by a multi input multi output (MIMO) control law that enhances stability by reducing the dependence of the forward and backward gyroscopic poles with changes in flywheel speed. The control law is shown to be effective even for (1) Large polar to transverse inertia ratios which increases the stored energy density while causing the poles to become more speed dependent and, (2) Low bandwidth controllers shaped to suppress high frequency noise. These two main tasks could be successfully achieved by MIMO (Gyroscopic) control algorithm, which is unique approach. The vibration control mass (VCM) is designed to reduce the vibrations of flexible appendages of the satellite. During IPAC maneuver, the oscillation of flywheel spin speeds, torque motions and satellite appendages are significantly reduced compared without VCM. Several different properties are demonstrated to obtain optimal VCM. Notch, band-pass and low-pass filters are implemented in the AMB system to reduce and cancel high frequency, dynamic bearing forces and motor torques due to flywheel mass imbalance. The transmitted forces and torques to satellite are considerably decreased in the present of both notch and band-pass filter stages. Successful IPAC simulation

  6. Satellite cascade attitude control via fuzzy PD controller with active force control under momentum dumping

    NASA Astrophysics Data System (ADS)

    Ismail, Z.; Varatharajoo, R.

    2016-10-01

    In this paper, fuzzy proportional-derivative (PD) controller with active force control (AFC) scheme is studied and employed in the satellite attitude control system equipped with reaction wheels. The momentum dumping is enabled via proportional integral (PI) controller as the system is impractical without momentum dumping control. The attitude controllers are developed together with their governing equations and evaluated through numerical treatment with respect to a reference satellite mission. From the results, it is evident that the three axis attitudes accuracies can be improved up to ±0.001 degree through the fuzzy PD controller with AFC scheme for the attitude control. In addition, the three-axis wheel angular momentums are well maintained during the attitude control tasks.

  7. Porcine satellite cells are restricted to a phenotype resembling their muscle origin.

    PubMed

    Zhu, H; Park, S; Scheffler, J M; Kuang, S; Grant, A L; Gerrard, D E

    2013-10-01

    Muscles in most domestic animals differ in function and growth potential based largely on muscle fiber type composition. Though much is known about satellite cells (SC), information is limited regarding how populations of SC differ with muscle fiber type, especially in pigs. Therefore, the objective of this study was to isolate and culture SC from red (RST) and white (WST) portions of the semitendinosus muscle of neonatal and adult pigs and determine their capacity to proliferate, differentiate, and express various myosin heavy chain (MyHC) isoforms in vitro. Porcine satellite cells were isolated from RST and WST muscles of 6-wk-old and adult (>6-mo-old) pigs and cultured under standard conditions. Muscle from neonatal pigs yielded nearly 10 times more (P < 0.001) presumptive satellite cells as those from adult pigs, with fusion percentages close to 60% for the former. The RST yielded more (P < 0.001) SC per gram muscle compared to WST, 8.1 ± 0.2 × 10(4) cells versus 6.7 ± 0.1 × 10(4) cells/gram muscle in young pigs, and 9.7 ± 0.4 × 10(3) cells versus 5.5 ± 0.4 × 10(3) cells/gram muscle in adult pigs, respectively. Likewise, satellite cells from RST proliferated faster (P < 0.001) than those from WST across both ages, as indicated by a shorter cell doubling time, 18.6 ± 0.8 h versus 21.3 ± 0.9 h in young pigs, and 23.2 ± 0.7 h versus 26.7 ± 0.9 h in adult pigs, respectively. As a result of shorter times to confluence, satellite cells from RST also formed myotubes earlier than those SC originating from WST. Once induced, however, SC from WST differentiated and fused faster (P < 0.05) as evidenced by fusion percentage within the first 24 h, 41.6% versus 34.3%, respectively; but reached similar ultimate fusion percentages similar to WST by 48 h. Over 90% of MyHC expressed in maximally fused SC cultures from both RST and WST was restricted to the embryonic isoform. Type IIX MyHC mRNA was not detected in any culture. Myotube cultures from RST expressed more

  8. Charge efficiency of Ni/H2 cells during transfer orbit of Telstar 4 satellites

    NASA Astrophysics Data System (ADS)

    Fang, W. C.; Maurer, Dean W.; Vyas, B.; Thomas, M. N.

    1994-02-01

    The TELSTAR 4 communication satellites being manufactured by Martin Marietta Astro Space (Astro Space) for AT&T are three axis stabilized spacecraft scheduled to be launched on expendable vehicles such as the Atlas or Ariane rockets. Typically, these spacecraft consist of a box that holds the electronics and supports the antenna reflectors and the solar array wings. The wings and reflectors are folded against the sides of the box during launch and the spacecraft is spun for attitude control in that phase; they are then deployed after achieving the final orbit. The launch phase and transfer orbits required to achieve the final geosynchronous orbit typically take 4 to 5 days during which time the power required for command, telemetry, attitude control, heaters, etc., is provided by two 50 AH nickel hydrogen batteries augmented by the exposed outboard solar panels. In the past, this situation has presented no problem since there was a considerable excess of power available from the array. In the case of large high powered spacecraft such as TELSTAR 4, however, the design power levels in transfer orbit approach the time-averaged power available from the exposed surface area of the solar arrays, resulting in a very tight power margin. To compound the difficulty, the array output of the spinning spacecraft in transfer orbit is shaped like a full wave rectified sine function and provides very low charging rates to the batteries during portions of the rotation. In view of the typically low charging efficiency of alkaline nickel batteries at low rates, it was decided to measure the efficiency during a simulation of the TELSTAR 4 conditions at the expected power levels and temperatures on three nickel hydrogen cells of similar design. The unique feature of nickel hydrogen cells that makes the continuous measurement of efficiency possible is that hydrogen is one of the active materials and thus, cell pressure is a direct measure of the state of charge or available capacity

  9. Charge efficiency of Ni/H2 cells during transfer orbit of Telstar 4 satellites

    NASA Technical Reports Server (NTRS)

    Fang, W. C.; Maurer, Dean W.; Vyas, B.; Thomas, M. N.

    1994-01-01

    The TELSTAR 4 communication satellites being manufactured by Martin Marietta Astro Space (Astro Space) for AT&T are three axis stabilized spacecraft scheduled to be launched on expendable vehicles such as the Atlas or Ariane rockets. Typically, these spacecraft consist of a box that holds the electronics and supports the antenna reflectors and the solar array wings. The wings and reflectors are folded against the sides of the box during launch and the spacecraft is spun for attitude control in that phase; they are then deployed after achieving the final orbit. The launch phase and transfer orbits required to achieve the final geosynchronous orbit typically take 4 to 5 days during which time the power required for command, telemetry, attitude control, heaters, etc., is provided by two 50 AH nickel hydrogen batteries augmented by the exposed outboard solar panels. In the past, this situation has presented no problem since there was a considerable excess of power available from the array. In the case of large high powered spacecraft such as TELSTAR 4, however, the design power levels in transfer orbit approach the time-averaged power available from the exposed surface area of the solar arrays, resulting in a very tight power margin. To compound the difficulty, the array output of the spinning spacecraft in transfer orbit is shaped like a full wave rectified sine function and provides very low charging rates to the batteries during portions of the rotation. In view of the typically low charging efficiency of alkaline nickel batteries at low rates, it was decided to measure the efficiency during a simulation of the TELSTAR 4 conditions at the expected power levels and temperatures on three nickel hydrogen cells of similar design. The unique feature of nickel hydrogen cells that makes the continuous measurement of efficiency possible is that hydrogen is one of the active materials and thus, cell pressure is a direct measure of the state of charge or available capacity

  10. Mature adult dystrophic mouse muscle environment does not impede efficient engrafted satellite cell regeneration and self-renewal.

    PubMed

    Boldrin, Luisa; Zammit, Peter Steven; Muntoni, Francesco; Morgan, Jennifer Elizabeth

    2009-10-01

    Changes that occur in the skeletal muscle environment with the progress of muscular dystrophies may affect stem cell function and result in impaired muscle regeneration. It has previously been suggested that the success of stem cell transplantation could therefore be dependent both on the properties of the cell itself and on the host muscle environment. Here we engrafted young and mature adult mdx-nude mice, which are the genetic homolog of Duchenne muscular dystrophy, with a small number of satellite cells freshly isolated from young, normal donor mice. We found that the donor satellite cells contributed to muscle regeneration and self-renewal as efficiently within mature adult, as in young, dystrophic host muscle. Donor-derived satellite cells also contributed to robust regeneration after further injury, showing that they were functional despite the more advanced dystrophic muscle environment. These findings provide evidence that muscle tissue in a later stage of dystrophy may be effectively treated by stem cells.

  11. Immunotherapy and mast cell activation.

    PubMed

    Carlos, A G; Carlos, M L; Santos, M A; Pedro, E; Santos, S; Lopes-Pregal, A

    1998-10-01

    Tryptase is the more specific markers for mast cell activation and mediators release and can be used as an index of mast cell activation after challenge. Nasal provocation tests have been done in patients allergic to the pollen of Parietaria (pellitory wall) before and after specific systemic immunotherapy and tryptase release evaluated in nasal lavage fluid. After specific immunotherapy the concentration of tryptase in nasal lavage was significantly decreased to all the concentrations used in challenge and the peack of tryptase release was delayed. These results confirm that assays of tryptase in nasal fluid after nasal provocation are a reliable markers of mast cell activation. Immunotherapy with specific allergen decreases mast cell reactivity to the same allergen.

  12. News of Brazilian space activities. [use of satellite data in meteorology and Earth resources programs

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Remote sensing and meteorological observations of satellites are covered. Development of an oceanographic atlas, prediction of droughts, and results of geological surveys using satellite data are discussed.

  13. Various light source treatments affect body and skeletal muscle growth by affecting skeletal muscle satellite cell proliferation in broilers.

    PubMed

    Halevy, O; Biran, I; Rozenboim, I

    1998-06-01

    In this study we addressed the effect of various monochromatic light treatments on muscle growth and satellite cell proliferation in broilers (Gallus domesticus). Broilers were reared under green (560 nm), blue (480 nm) and red (660 nm) monochromatic lights and white light as a control from day one until 35 days of age. At five days of age, satellite cells were prepared from the experimental chicks. The number of satellite cells per gram of breast muscle and total number of satellite cells derived from the experimental broilers was substantially higher in the groups reared under green and blue light, compared to the red and white light groups. Growth hormone receptor gene expression was also higher in the former groups. High correlation was found between the breast muscle weight observed on day 35 and the number of satellite cells per gram of breast muscle (r = 0.915) and total number of satellite cells (r = 0.833), derived from the experimental chicks as early as five days of age. In addition, the protein/DNA ratio found in breast muscle at 35 days of age was significantly lower in chicks that were reared under green and blue lights. The lowest ratio which was found in the green group and was twice as low as in the control group, indicates the highest number of nuclei in the former group. As satellite cells are the only source of additional nuclei in skeletal muscles of postnatal animals, our results suggest that the higher muscle weight found in the green and blue light groups was due to increased satellite cell proliferation during the first days of age.

  14. Fabrication of glass gas cells for the HALOE and MAPS satellite experiments

    NASA Technical Reports Server (NTRS)

    Sullivan, E. M.; Walthall, H. G.

    1984-01-01

    The Halogen Occultation Experiment (HALOE) and the Measurement of Air Pollution from Satellites (MAPS) experiment are satellite-borne experiments which measure trace constituents in the Earth's atmosphere. The instruments which obtain the data for these experiments are based on the gas filter correlation radiometer measurement technique. In this technique, small samples of the gases of interest are encapsulated in glass cylinders, called gas cells, which act as very selective optical filters. This report describes the techniques employed in the fabrication of the gas cells for the HALOE and MAPS instruments. Details of the method used to fuse the sapphire windows (required for IR transmission) to the glass cell bodies are presented along with detailed descriptions of the jigs and fixtures used during the assembly process. The techniques and equipment used for window inspection and for pairing the HALOE windows are discussed. Cell body materials and the steps involved in preparing the cell bodies for the glass-to-sapphire fusion process are given.

  15. Active-passive integrated vibration control for control moment gyros and its application to satellites

    NASA Astrophysics Data System (ADS)

    Zhang, Yao; Zang, Yue; Li, Mou; Wang, Youyi; Li, Wenbo

    2017-04-01

    The strategy of active-passive integrated vibration control on the truss enveloping control moment gyroscopes (CMGs) is presented and its characteristics of time domain and frequency domain are analyzed. Truss enveloping CMGs contains pyramid-type CMGs, which are enveloped by multiple struts. These struts can be employed to realize the active-passive integrated vibration control. In addition, the struts of the trusses can maintain the working space of CMGs. Firstly, the disturbance characteristics of CMGs are analyzed considering static and dynamic imbalances of the CMG's rotor; then, an active-passive integrated vibration isolation truss structure is developed based on its characteristics. This structure can restrain the CMG vibration as much as possible and reduce its influence on the photographic quality of optical payloads. Next, the dynamic model of the active-passive vibration isolation truss structure is established. The frequency domain analysis of this model shows that the active-passive integrated vibration control method can restrain the high-frequency vibration and also improve the characteristics of low-frequency vibration. Finally, the dynamic model for the whole satellite is built with this type of CMGs. The time domain simulations of satellite attitude control verify the attitude control improvements resulting from the CMGs vibration control strategy.

  16. Risk Reduction Activities for the Near-Earth Object Surveillance Satellite Project

    NASA Astrophysics Data System (ADS)

    Bédard, D.; Scott, L.; Wallace, B.; Harvey, W.

    every three minutes, for an average of 288 images for every 24 hours of operation. To ensure both science teams can employ the NEOSSat spacecraft to its full potential, the Mission Planning System (MPS) will automate the scheduling of both the HEOSS and NESS observation tasks. In another risk reduction effort for the NEOSSat project, a prototype of the MPS software has been developed to help in the definition of the system requirements as well as to identify and reduce the risks associated with the development of this software system. The paper will first provide an update on the status and schedule of the NEOSSat project. Then, we will present the results achieved (metrics and photometry) from the two tracked GPS spacecraft as well as the lessons learned that are being applied during the development of the joint DRDC and CSA NEOSSat micro-satellite. Finally, results obtained from the MPS prototype development will be presented with a special emphasis on the final system to be designed including a description of the functions judged to be critical based upon the risk reduction activity.

  17. Views of Growing Methane Emissions near Oil and Natural Gas Activity: Satellite, Aircraft, and Ground

    NASA Astrophysics Data System (ADS)

    Kollonige, D. E.; Thompson, A. M.; Diskin, G. S.; Hannigan, J. W.; Nussbaumer, E.

    2015-12-01

    To better understand the discrepancies between current top-down and bottom-up estimates, additional methane (CH4) measurements are necessary for regions surrounding growing oil and natural gas (ONG) development. We have evaluated satellite measurements of CH4 in US regions with ONG operations for their application as "top-down" constraints (part of the NASA Air Quality Applied Sciences Team (AQAST) project). For validation of the satellite instruments' sensitivities to emitted gases, we focus on regions where the DISCOVER-AQ (Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality) campaign deployed ground and aircraft measurements in Maryland (2011), California and Texas (2013), and Colorado (2014). The largest CH4 signals were observed in the Greater Green River and Powder River Basins using Tropospheric Emission Spectrometer (TES) Representative Tropospheric Volume Mixing Ratio (RTVMR) measurements. A long-term comparison between a ground remote-sensing Fourier Transform Spectrometer (FTS) at Boulder and TES for 2010-2013 shows good correlation and differences ranging 2.5-5% for their yearly distribution of total column CH4. To determine any correlation between lower/mid-tropospheric CH4 (where a thermal IR sensor, such as TES, is most sensitive) and near-surface/boundary CH4 (where sources emit), we analyze the variability of DISCOVER-AQ aircraft profiles using principal component analysis and assess the correlation between near-surface (0-2 km) and mid-tropospheric (>2 km) CH4 concentrations. Using these relationships, we estimate near-surface CH4 using mid-tropospheric satellite measurements based on the partial column amounts within vertical layers with a linear regression. From this analysis, we will demonstrate whether the uncertainties of satellite-estimated near-surface CH4 are comparable to observed variability near ONG activity. These results will assist validation of satellite instrument

  18. Suppression of collagen Q expression in the extrajunctional regions of rat fast muscles is encoded in their stem cells (satellite cells).

    PubMed

    Glišović, Špela; Pregelj, Peter; Dolenc, Igor; Sketelj, Janez

    2013-03-25

    In rat fast muscles, collagen Q (ColQ) expression is restricted to the neuromuscular junctions. In contrast, it is high also extrajunctionally in the slow soleus muscles. Fast muscles activated by chronic low-frequency electrical stimulation, similar to neural activation of the soleus muscles, did not increase their extrajunctional expression of ColQ. We assumed that the myogenic stem cells (satellite cells) in fast and slow muscles were intrinsically different in regard to the capacity that they convey to their respective muscle fibers to increase the extrajunctional ColQ expression upon innervation. ColQ mRNA levels were determined by quantitative real-time PCR. Extensive neural suppression of the extrajunctional ColQ expression in regenerating fast muscles during maturation is a very slow process requiring 30-60 days. If the immature regenerating fast EDL muscles were indirectly or directly electrically stimulated immediately after innervation by chronic low-frequency impulse pattern for 8 days, no significant increase of the extrajunctional ColQ mRNA levels was observed in stimulated regenerates in comparison to non-stimulated ones. In contrast, the extrajunctional ColQ mRNA levels in the regenerates of the soleus muscles, trans-innervated by the EDL nerve at the time of muscle injury, increased 4- to 5-fold after 8 days of the same chronic low-frequency electrical stimulation in comparison to those in the stimulated EDL regenerates. Since both fast and slow muscles completely regenerated only from their own myogenic stem cells and were innervated by the same nerve and later activated by the same tonic pattern of impulses, these results demonstrated that the mechanism causing incapacity of regenerating fast muscles to increase their extrajunctional ColQ expression upon tonic activation is encoded in their satellite cells, which in this respect differ from those in the slow muscles.

  19. Monitoring active volcanism using ASTER satellite remote sensing: Volcan de Colima, Colima, Mexico

    NASA Astrophysics Data System (ADS)

    Silvertooth, Maggie Lin

    Scope and Method of Study. ASTER satellite data was collected and analyzed in order to quantify changes in temperature, vesicularity, and morphology of the dome and crater that support evidence of constructive and destructive phases of lava dome growth and destruction cycles. These cycles are characterized by sporadic growth of a lava dome that is subsequently destroyed by a Vulcanian or Pelean style eruption. Activity reports were compared with ASTER images and new deposits were mapped along the flanks of the volcano. There is no way to distinguish between pyroclastic material, rockfall deposits, lahar deposits or lava flows therefore all new flows were mapped. Findings and Conclusions. During a constructive phase, magma that is low in volatiles rises and forms a new dome. The low amount of volatiles leads to a decrease in vesicularity. Therefore during a destructive phase vesicularity is increased. Examining changes in temperature on the dome, it appears that temperatures are at a maximum before an eruptive event, such as incandescent material being extruded at the edge of the dome. Immediately after the lava dome is removed by an explosive event, a decrease in temperature is observed. Once activity resumes, increase in temperature is seen. Morphological changes on the dome can be due to explosive events, gravitational collapse, and factors affecting the endogenous and exogenous growth of the dome. Satellite data provides a synoptic view allowing for observation of new activity to be observed earlier than ground based data may allow. In the case of the Volcan de Colima, satellite remote sensing provided insight to the constructive and destructive phases of the lava dome and current activity.

  20. Somatostatin modulates mast cell-induced responses in murine spinal neurons and satellite cells.

    PubMed

    Van Op den bosch, Joeri; Van Nassauw, Luc; Van Marck, Eric; Timmermans, Jean-Pierre

    2009-08-01

    The course of intestinal inflammatory responses is tightly coordinated by the extensive communication between the immune system and the enteric nervous system, among which the bidirectional mast cell-neuron interaction within the intestinal wall plays a prominent role. Recent research suggests that somatostatin (SOM) is able to inhibit this self-reinforcing network by simultaneously suppressing the inflammatory activities of both neurons and mast cells. Therefore, we assessed the modulatory effects of SOM on both the short-term and long-term effects induced by the main mast cell mediators histamine (HIS) and 5-HT on spinal sensory neurons. Short-term incubation of dorsal root ganglion cultures with HIS and 5-HT induced neuronal CGRP-release and calcium-mediated activation of both neurons and nonneuronal cells, both of which effects were significantly reduced by SOM. In addition, SOM was also able to suppress the increased neuronal expression of pro- and anti-inflammatory peptides induced by long-term exposure to HIS and 5-HT. Immunocytochemical and molecular-biological experiments revealed the possible involvement of somatostatin receptor 1 (SSTR1) and SSTR2A in these profound SOM-dependent effects. These data, combined with the increased expression of pro- and anti-inflammatory peptides and several SSTRs in murine dorsal root ganglia following intestinal inflammation, reveal that intestinal inflammation not only induces the onset of proinflammatory cascades but simultaneously triggers endogenous systems destined to prevent excessive tissue damage. Moreover, these data provide for the first time functional evidence that SOM is able to directly modulate intestinal inflammatory responses by interference with the coordinating mast cell-neuron communication.

  1. Monitoring of Surface Wetness from active microwave satellite data in permafrost regions

    NASA Astrophysics Data System (ADS)

    Bartsch, A.; Boike, J.; Sabel, D.; Wagner, W.

    2008-12-01

    Soil moisture content impacts land surface energy dynamics, regional runoff dynamics and vegetation productivity. Coarse to medium resolution data from active microwave instruments onboard satellites which are currently in space are able to provide such valuable information for operational use. Scatterometer (ERS, Metop ASCAT) can be applied on regional to global scale. ScanSAR systems are suitable for regional to continental monitoring and for the investigation of scaling issues. The original approach which was developed for scatterometer data (Wagner et al. 1999) has been transferred to ScanSAR data within the framework of the ESA Tiger innovator project SHARE (www.ipf.tuwien.ac.at/radar/share). Data from the ENVISAT ASAR instrument operating in Global Mode (1km resolution) have not only been used over the southern African subcontinent, but also over entire Australia and within other regional studies. Current research focuses on the validation and investigation of scaling issues of satellite derived surface wetness in permafrost environment. A comparison to soil moisture measurements has been carried out over the Lena- Delta, Russia. Measurements are from a site on Samoylov Island, which is characterized by polygonal tundra. Best aggreement of the 1km resolution satellit data was found for polygon centres, with a Pearson correlation of 0.72. Timeseries analyses from this and other sites in Siberia will be presented.

  2. Computational simulation of extravehicular activity dynamics during a satellite capture attempt.

    PubMed

    Schaffner, G; Newman, D J; Robinson, S K

    2000-01-01

    A more quantitative approach to the analysis of astronaut extravehicular activity (EVA) tasks is needed because of their increasing complexity, particularly in preparation for the on-orbit assembly of the International Space Station. Existing useful EVA computer analyses produce either high-resolution three-dimensional computer images based on anthropometric representations or empirically derived predictions of astronaut strength based on lean body mass and the position and velocity of body joints but do not provide multibody dynamic analysis of EVA tasks. Our physics-based methodology helps fill the current gap in quantitative analysis of astronaut EVA by providing a multisegment human model and solving the equations of motion in a high-fidelity simulation of the system dynamics. The simulation work described here improves on the realism of previous efforts by including three-dimensional astronaut motion, incorporating joint stops to account for the physiological limits of range of motion, and incorporating use of constraint forces to model interaction with objects. To demonstrate the utility of this approach, the simulation is modeled on an actual EVA task, namely, the attempted capture of a spinning Intelsat VI satellite during STS-49 in May 1992. Repeated capture attempts by an EVA crewmember were unsuccessful because the capture bar could not be held in contact with the satellite long enough for the capture latches to fire and successfully retrieve the satellite.

  3. Effect of TCEA3 on the differentiation of bovine skeletal muscle satellite cells.

    PubMed

    Zhu, Yue; Tong, Hui-Li; Li, Shu-Feng; Yan, Yun-Qin

    2017-03-18

    Bovine muscle-derived satellite cells (MDSCs) are important for animal growth. In this study, the effect of transcription elongation factor A3 (TCEA3) on bovine MDSC differentiation was investigated. Western blotting, immunofluorescence assays, and cytoplasmic and nuclear protein isolation and purification techniques were used to determine the expression pattern and protein localization of TCEA3 in bovine MDSCs during in vitro differentiation. TCEA3 expression was upregulated using the CRISPR/Cas9 technique to study its effects on MDSC differentiation in vitro. TCEA3 expression gradually increased during the in vitro differentiation of bovine MDSCs and peaked on the 5th day of differentiation. TCEA3 was mainly localized in the cytoplasm of bovine MDSCs, and its expression was not detected in the nucleus. The level of TCEA3 was relatively higher in myotubes at a higher degree of differentiation than during early differentiation. After transfection with a TCEA3-activating plasmid vector (TCEA3 overexpression) for 24 h, the myotube fusion rate, number of myotubes, and expression levels of the muscle differentiation-related loci myogenin (MYOG) and myosin heavy chain 3 (MYH3) increased significantly during the in vitro differentiation of bovine MDSCs. After transfection with a TCEA3-inhibiting plasmid vector for 24 h, the myotube fusion rate, number of myotubes, and expression levels of MYOG and MYH3 decreased significantly. Our results indicated, for the first time, that TCEA3 promotes the differentiation of bovine MDSCs and have implications for meat production and animal rearing.

  4. The role of radiation hard solar cells in minimizing the costs of global satellite communications systems

    NASA Technical Reports Server (NTRS)

    Summers, Geoffrey P.; Walters, Robert J.; Messenger, Scott R.; Burke, Edward A.

    1995-01-01

    An analysis embodied in a PC computer program is presented which quantitatively demonstrates how the availability of radiation hard solar cells can minimize the cost of a global satellite communication system. The chief distinction between the currently proposed systems, such as Iridium Odyssey and Ellipsat, is the number of satellites employed and their operating altitudes. Analysis of the major costs associated with implementing these systems shows that operation within the earth's radiation belts can reduce the total system cost by as much as a factor of two, so long as radiation hard components including solar cells, can be used. A detailed evaluation of several types of planar solar cells is given, including commercially available Si and GaAs/Ge cells, and InP/Si cells which are under development. The computer program calculates the end of life (EOL) power density of solar arrays taking into account the cell geometry, coverglass thickness, support frame, electrical interconnects, etc. The EOL power density can be determined for any altitude from low earth orbit (LEO) to geosynchronous (GEO) and for equatorial to polar planes of inclination. The mission duration can be varied over the entire range planned for the proposed satellite systems. An algorithm is included in the program for determining the degradation of cell efficiency for different cell technologies due to proton and electron irradiation. The program can be used to determine the optimum configuration for any cell technology for a particular orbit and for a specified mission life. Several examples of applying the program are presented, in which it is shown that the EOL power density of different technologies can vary by an order of magnitude for certain missions. Therefore, although a relatively radiation soft technology can be made to provide the required EOL power by simply increasing the size of the array, the impact on the total system budget could be unacceptable, due to increased launch and

  5. Glutamate release from satellite glial cells of the murine trigeminal ganglion.

    PubMed

    Wagner, Lysann; Warwick, Rebekah A; Pannicke, Thomas; Reichenbach, Andreas; Grosche, Antje; Hanani, Menachem

    2014-08-22

    It has been proposed that glutamate serves as a mediator between neurons and satellite glial cells (SGCs) in sensory ganglia and that SGCs release glutamate. Using a novel method, we studied glutamate release from SGCs from murine trigeminal ganglia. Sensory neurons with adhering SGCs were enzymatically isolated from wild type and transgenic mice in which vesicular exocytosis was suppressed in glial cells. Extracellular glutamate was detected by microfluorimetry. After loading the cells with a photolabile Ca(2+) chelator, the intracellular Ca(2+) concentration was raised in SGCs by a UV pulse, which resulted in glutamate release. The amount of released glutamate was decreased in cells with suppressed exocytosis and after pharmacological block of hemichannels. The data demonstrate that SGCs of the trigeminal ganglion release glutamate in a Ca(2+)-dependent manner.

  6. PPARγ and MyoD are differentially regulated by myostatin in adipose-derived stem cells and muscle satellite cells

    SciTech Connect

    Zhang, Feng; Deng, Bing; Wen, Jianghui; Chen, Kun; Liu, Wu; Ye, Shengqiang; Huang, Haijun; Jiang, Siwen; Xiong, Yuanzhu

    2015-03-06

    Myostatin (MSTN) is a secreted protein belonging to the transforming growth factor-β (TGF-β) family that is primarily expressed in skeletal muscle and also functions in adipocyte maturation. Studies have shown that MSTN can inhibit adipogenesis in muscle satellite cells (MSCs) but not in adipose-derived stem cells (ADSCs). However, the mechanism by which MSTN differently regulates adipogenesis in these two cell types remains unknown. Peroxisome proliferator-activated receptor-γ (PPARγ) and myogenic differentiation factor (MyoD) are two key transcription factors in fat and muscle cell development that influence adipogenesis. To investigate whether MSTN differentially regulates PPARγ and MyoD, we analyzed PPARγ and MyoD expression by assessing mRNA, protein and methylation levels in ADSCs and MSCs after treatment with 100 ng/mL MSTN for 0, 24, and 48 h. PPARγ mRNA levels were downregulated after 24 h and upregulated after 48 h of treatment in ADSCs, whereas in MSCs, PPARγ levels were downregulated at both time points. MyoD expression was significantly increased in ADSCs and decreased in MSCs. PPARγ and MyoD protein levels were upregulated in ADSCs and downregulated in MSCs. The CpG methylation levels of the PPARγ and MyoD promoters were decreased in ADSCs and increased in MSCs. Therefore, this study demonstrated that the different regulatory adipogenic roles of MSTN in ADSCs and MSCs act by differentially regulating PPARγ and MyoD expression. - Highlights: • PPARγ and MyoD mRNA and protein levels are upregulated by myostatin in ADSCs. • PPARγ and MyoD mRNA and protein levels are downregulated by myostatin in MSCs. • PPARγ exhibited different methylation levels in myostatin-treated ADSCs and MSCs. • MyoD exhibited different methylation levels in myostatin-treated ADSCs and MSCs. • PPARγ and MyoD are differentially regulated by myostatin in ADSCs and MSCs.

  7. Differentiation rather than aging of muscle stem cells abolishes their telomerase activity

    PubMed Central

    O’Connor, Matthew S.; Carlson, Morgan E.; Conboy, Irina M.

    2009-01-01

    A general feature of stem cells is the ability to routinely proliferate in order to build, maintain, and repair organ systems. Accordingly, embryonic and germline, as well as some adult stem cells, produce the telomerase enzyme at various levels of expression. Our results show that, while muscle is a largely post-mitotic tissue, the muscle stem cells (satellite cells) that maintain this biological system throughout adult life do indeed display robust telomerase activity. Conversely, primary myoblasts (the immediate progeny of satellite cells) quickly and dramatically down-regulate telomerase activity. This work thus suggests that satellite cells, and early transient myoblasts, may be more promising therapeutic candidates for regenerative medicine than traditionally utilized myoblast cultures. Muscle atrophy accompanies human aging, and satellite cells endogenous to aged muscle can be triggered to regenerate old tissue by exogenous molecular cues. Therefore, we also examined whether these aged muscle stem cells would produce tissue that is “young” with respect to telomere maintenance. Interestingly, this work shows that the telomerase activity in muscle stem cells is largely retained into old age wintin inbred “long” telomere mice and in wild-derived short telomere mouse strains, and that age-specific telomere shortening is undetectable in the old differentiated muscle fibers of either strain. Summarily, this work establishes that young and old muscle stem cells, but not necessarily their progeny, myoblasts, are likely to produce tissue with normal telomere maintenance when used in molecular and regenerative medicine approaches for tissue repair. PMID:19455648

  8. Satellite cell proliferation in murine sensory ganglia in response to scarification of the skin.

    PubMed

    Elson, Karen; Simmons, Anthony; Speck, Peter

    2004-01-01

    Satellite cells (SCs) ensheathe neuronal cell bodies of sensory ganglia and provide mechanical and metabolic support for neurons. In mice, grossly detrimental stimuli such as nerve crush or cut, or explant culture of ganglia induce proliferation of SCs. It is unknown whether SC proliferation occurs in response to the less severe trauma that might commonly occur in a physiological situation. Our aim was to determine the response of SCs to mild trauma, such as scratching the skin. SC proliferation, measured by bromodeoxyuridine (BrdU) uptake, and immune cells, measured by CD45 labelling, were quantified at various times during the 7 days after scarification or abrasion of flank skin. We show that minimal skin trauma, such as scarification or light abrasion, triggers proliferation of SCs. Sections of control mice nervous tissue show <10 BrdU+ cells/ganglionic profile. In contrast, sections of traumatised mice show >50 BrdU+ cells/ganglionic profile, even after simply scratching the skin. The lack of CD45+ cells shows that the proliferating cells are not immune cells. We suggest that SCs in mice are a labile cell population able to proliferate rapidly in response to minimal nerve trauma. This finding has implications for the role of SCs in nervous system repair.

  9. A novel approach to collecting satellite cells from adult skeletal muscles on the basis of their stress tolerance.

    PubMed

    Shigemoto, Taeko; Kuroda, Yasumasa; Wakao, Shohei; Dezawa, Mari

    2013-07-01

    Stem cells are generally collected using flow cytometry, but this method is not applicable when the cell surface marker is not well determined. Satellite cells, which are skeletal muscle stem cells, have the ability to regenerate damaged muscles and are expected to be applicable for treatment of muscle degeneration. Although the transcription factor Pax7 is a known specific marker of satellite cells, it is not located on the cell surface and therefore flow cytometry is not directly applicable. In the present study, we turned our attention to the stress tolerance of adult stem cells, and we propose long-term trypsin incubation (LTT) as a novel approach to collecting satellite cells from mouse and human skeletal muscles. LTT led to a remarkable increase in the ratio of Pax7(+) cells that retain normal myogenic stem cell function. In particular, human Pax7(+) cells made up approximately 30% of primary cultured cells, whereas after LTT, the ratio of Pax7(+) cells increased up to ∼80%, and the ratio of Pax7(+) and/or MyoD(+) myogenic cells increased to ∼95%. Once transplanted, LTT-treated cells contributed to subsequent muscle regeneration following repetitive muscle damage without additional cell transplantation. The stress tolerance of Pax7(+) cells is related to heat shock protein 27 and αB-crystallin, members of the small heat shock protein family. This approach, based on the stress resistance of adult stem cells, is a safe and inexpensive method of efficiently collecting human satellite cells and may also be used for collecting other tissue stem cells whose surface marker is unknown.

  10. Surveillance of waste disposal activity at sea using satellite ocean color imagers: GOCI and MODIS

    NASA Astrophysics Data System (ADS)

    Hong, Gi Hoon; Yang, Dong Beom; Lee, Hyun-Mi; Yang, Sung Ryull; Chung, Hee Woon; Kim, Chang Joon; Kim, Young-Il; Chung, Chang Soo; Ahn, Yu-Hwan; Park, Young-Je; Moon, Jeong-Eon

    2012-09-01

    Korean Geostationary Ocean Color Imager (GOCI) and Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua observations of the variation in ocean color at the sea surface were utilized to monitor the impact of nutrient-rich sewage sludge disposal in the oligotrophic area of the Yellow Sea. MODIS revealed that algal blooms persisted in the spring annually at the dump site in the Yellow Sea since year 2000 to the present. A number of implications of using products of the satellite ocean color imagers were exploited here based on the measurements in the Yellow Sea. GOCI observes almost every hour during the daylight period, every day since June 2011. Therefore, GOCI provides a powerful tool to monitor waste disposal at sea in real time. Tracking of disposal activity from a large tanker was possible hour by hour from the GOCI timeseries images compared to MODIS. Smaller changes in the color of the ocean surface can be easily observed, as GOCI resolves images at smaller scales in space and time in comparison to polar orbiting satellites, e.g., MODIS. GOCI may be widely used to monitor various marine activities in the sea, including waste disposal activity from ships.

  11. Myofiber-specific TEAD1 overexpression drives satellite cell hyperplasia and counters pathological effects of dystrophin deficiency

    PubMed Central

    Southard, Sheryl; Kim, Ju-Ryoung; Low, SiewHui; Tsika, Richard W; Lepper, Christoph

    2016-01-01

    When unperturbed, somatic stem cells are poised to affect immediate tissue restoration upon trauma. Yet, little is known regarding the mechanistic basis controlling initial and homeostatic ‘scaling’ of stem cell pool sizes relative to their target tissues for effective regeneration. Here, we show that TEAD1-expressing skeletal muscle of transgenic mice features a dramatic hyperplasia of muscle stem cells (i.e. satellite cells, SCs) but surprisingly without affecting muscle tissue size. Super-numeral SCs attain a ‘normal’ quiescent state, accelerate regeneration, and maintain regenerative capacity over several injury-induced regeneration bouts. In dystrophic muscle, the TEAD1 transgene also ameliorated the pathology. We further demonstrate that hyperplastic SCs accumulate non-cell-autonomously via signal(s) from the TEAD1-expressing myofiber, suggesting that myofiber-specific TEAD1 overexpression activates a physiological signaling pathway(s) that determines initial and homeostatic SC pool size. We propose that TEAD1 and its downstream effectors are medically relevant targets for enhancing muscle regeneration and ameliorating muscle pathology. DOI: http://dx.doi.org/10.7554/eLife.15461.001 PMID:27725085

  12. Correlated NOS-Imu and myf5 expression by satellite cells in mdx mouse muscle regeneration during NOS manipulation and deflazacort treatment.

    PubMed

    Anderson, Judy E; Vargas, Cinthya

    2003-06-01

    Satellite cells, muscle precursor cells in skeletal muscle, are normally quiescent and become activated by disease or injury. A lack of dystrophin and changes in the expression or activity of neuronal nitric oxide synthase (NOS-I) affect the timing of activation in vivo. Nitric oxide synthase inhibition delays muscle repair in normal mice, and worsens muscular dystrophy in the mdx mouse, a genetic homologue of Duchenne muscular dystrophy. However, the potential role of activation and repair events mediated by nitric oxide in determining the outcome of steroid or other treatments for muscular dystrophy is not clear. We tested the hypothesis that the extent of repair in dystrophic muscles of mdx mice is partly dependent on NOS-Imu expression and activity. Myotube formation in regenerating muscle was promoted by deflazacort treatment of mdx dystrophic mice (P<0.05), and improved by combination with the nitric oxide synthase substrate, L-arginine, especially in the diaphragm. NOS-Imu mRNA expression and activity were present in satellite cells and very new myotubes of regenerating and dystrophic muscle. Deflazacort treatment resulted in increased NOS-Imu expression in regenerating muscles in a strong and specific correlation with myf5 expression (r=0.95, P<0.01), a marker for muscle repair. Nitric oxide synthase inhibition prevented the deflazacort-induced rise in NOS-Imu and myf5 expression in the diaphragm without affecting the diameter of non-regenerating fibres. These in vivo studies suggest that gains in NOS-Imu expression and nitric oxide synthase activity in satellite cells can increase the extent and speed of repair, even in the absence of dystrophin in muscle fibres. NOS-Imu may be a useful therapeutic target to augment the effects of steroidal or other treatments of muscular dystrophy.

  13. Candidate solar cell materials for photovoltaic conversion in a solar power satellite /SPS/

    NASA Technical Reports Server (NTRS)

    Glaser, P. E.; Almgren, D. W.

    1978-01-01

    In recognition of the obstacles to solar-generated baseload power on earth, proposals have been made to locate solar power satellites in geosynchronous earth orbit (GEO), where solar energy would be available 24 hours a day during most of the time of the year. In an SPS, the electricity produced by solar energy conversion will be fed to microwave generators forming part of a planar phase-array transmitting antenna. The antenna is designed to precisely direct a microwave beam of very low intensity to one or more receiving antennas at desired locations on earth. At the receiving antenna, the microwave energy will be safely and efficiently reconverted to electricity and then be transmitted to consumers. An SPS system will include a number of satellites in GEO. Attention is given to the photovoltaic option for solar energy conversion in GEO, solar cell requirements, the availability of materials, the implication of large production volumes, requirements for high-volume manufacture of solar cell arrays, and the effects of concentration ratio on solar cell array area.

  14. Cytokine and satellite cell responses to muscle damage: interpretation and possible confounding factors in human studies.

    PubMed

    van de Vyver, M; Myburgh, K H

    2012-08-01

    It is plausible that multiple muscle biopsies following a muscle damaging intervention can exacerbate the inflammatory and subsequent satellite cell responses. To elucidate confounding effects of muscle biopsy procedure on satellite cell number, indirect markers of damage and the inflammatory response following acute downhill running (DHR) were investigated. 10 healthy male participant were divided into a non-exercising control (n = 4) and DHR (12 × 5min bouts, 10 % decline at 85 % VO(2)max) (n = 6) group. Blood samples were taken pre, post and every 24 h for 9 days. Serum was analysed for creatine kinase (CK), myoglobin (Mb), lactate dehydrogenase (LDH), TNF-α, IL-6 and IL-10. Muscle biopsies taken on days 1 and 2 post intervention from opposing legs were analysed for Pax7(+) satellite cells. In the DHR group, Mb (536 ± 277 ng mL(-1)), IL-6 (12.6 ± 4.7 pg mL(-1)) and IL-10 (27.3 ± 11.5 pg mL(-1)) peaked immediately post DHR, while CK (2651 ± 1911 U L(-1)), LDH (202 ± 47 U L(-1)) and TNF-α (25.1 ± 8.7 pg mL(-1)) peaked on day 1. A 30 % increase in Pax7(+) satellite cells on day 1 in the DHR group was no longer apparent on day 2. H&E staining show evidence of phagocytosis in the DHR group. No significant changes over time were observed in the control group for any of the variables measured. Events observed in the DHR group were as a result of the intervention protocol and subsequent muscle damage. The relationship between SC proliferation and pro-inflammatory cytokine release appears to be complex since the IL-6/IL-10 response time differs significantly from the TNF-α response.

  15. Regenerative fuel cell study for satellites in GEO orbit. Final contractor report

    SciTech Connect

    Levy, A.; Vandine, L.L.; Stedman, J.K.

    1987-07-01

    Summarized are the results of a 12-month study to identify high performance regenerative hydrogen-oxygen fuel cell concepts for geosynchronous satellite application. Emphasis was placed on concepts with the potential for high energy density (W-hr/lb) and passive means for water and heat management to maximize system reliability. Both polymer membrane and alkaline electrolyte fuel cells were considered, with emphasis on the alkaline cell because of its high performance, advanced state of development, and proven ability to operate in a launch and space environment. Three alkaline system concepts were studied. The first, the integrated design, utilized a configuration in which the fuel cell and electrolysis cells are alternately stacked inside a pressure vessel. Product water is transferred by diffusion during electrolysis and waste heat is conducted through the pressure wall, thus using completely passive means for transfer and control. The second alkaline system, the dedicated design, uses a separate fuel cell and electrolysis stack so that each unit can be optimized in size and weight based on its orbital operating period. The third design was a dual function stack configuration, in which each cell can operate in both fuel cell and electrolysis mode, thus eliminating the need for two separate stacks and associated equipment. Results indicate that using near term technology energy densities between 46 and 52 W-hr/lb can be achieved at efficiencies of 55 percent. System densities of 115 W-hr/lb are contemplated.

  16. Satellite observation of pollutant emissions from gas flaring activities near the Arctic

    NASA Astrophysics Data System (ADS)

    Li, Can; Hsu, N. Christina; Sayer, Andrew M.; Krotkov, Nickolay A.; Fu, Joshua S.; Lamsal, Lok N.; Lee, Jaehwa; Tsay, Si-Chee

    2016-05-01

    Gas flaring is a common practice in the oil industry that can have significant environmental impacts, but has until recently been largely overlooked in terms of relevance to climate change. We utilize data from various satellite sensors to examine pollutant emissions from oil exploitation activities in four areas near the Arctic. Despite the remoteness of these sparsely populated areas, tropospheric NO2 retrieved from the Ozone Monitoring Instrument (OMI) is substantial at ˜1 × 1015 molecules cm-2, suggesting sizeable emissions from these industrial activities. Statistically significant (at the 95% confidence level, corresponding uncertainties in parentheses) increasing trends of 0.017 (±0.01) × 1015 and 0.015 (±0.006) × 1015 molecules cm-2 year-1 over 2004-2015 were found for Bakken (USA) and Athabasca (Canada), two areas having recently experienced fast expansion in the oil industry. This rapid change has implications for emission inventories, which are updated less frequently. No significant trend was found for the North Sea (Europe), where oil production has been declining since the 1990s. For northern Russia, the trend was just under the 95% significance threshold at 0.0057 (±0.006) × 1015 molecules cm-2 year-1. This raises an interesting inconsistency as prior studies have suggested that, in contrast to the continued, albeit slow, expansion of Russian oil/gas production, gas flaring in Russia has decreased in recent years. However, only a fraction of oil fields in Russia were covered in our analysis. Satellite aerosol optical depth (AOD) data revealed similar tendencies, albeit at a weaker level of statistical significance, due to the longer lifetime of aerosols and contributions from other sources. This study demonstrates that synergetic use of data from multiple satellite sensors can provide valuable information on pollutant emission sources that is otherwise difficult to acquire.

  17. Survey: National Environmental Satellite Service

    NASA Technical Reports Server (NTRS)

    1977-01-01

    The national Environmental Satellite Service (NESS) receives data at periodic intervals from satellites of the Synchronous Meteorological Satellite/Geostationary Operational Environmental Satellite series and from the Improved TIROS (Television Infrared Observational Satellite) Operational Satellite. Within the conterminous United States, direct readout and processed products are distributed to users over facsimile networks from a central processing and data distribution facility. In addition, the NESS Satellite Field Stations analyze, interpret, and distribute processed geostationary satellite products to regional weather service activities.

  18. Solid State Inflation Balloon Active Deorbiter: Scalable Low-Cost Deorbit System for Small Satellites

    NASA Technical Reports Server (NTRS)

    Huang, Adam

    2016-01-01

    The goal of the Solid State Inflation Balloon Active Deorbiter project is to develop and demonstrate a scalable, simple, reliable, and low-cost active deorbiting system capable of controlling the downrange point of impact for the full-range of small satellites from 1 kg to 180 kg. The key enabling technology being developed is the Solid State Gas Generator (SSGG) chip, generating pure nitrogen gas from sodium azide (NaN3) micro-crystals. Coupled with a metalized nonelastic drag balloon, the complete Solid State Inflation Balloon (SSIB) system is capable of repeated inflation/deflation cycles. The SSGG minimizes size, weight, electrical power, and cost when compared to the current state of the art.

  19. Sentinel-3 Satellite Applications In The Monitoring Of The Active Forest Fires

    NASA Astrophysics Data System (ADS)

    Calle, A.; Gonzalez-Alonso, F.

    2013-12-01

    FRP (Fire Radiative Power) is the magnitude associated to the thermal radiance which explains the ecological effects of active fire; it is the component of the chemical power released from burning vegetation and emitted as radiation during the process of combustion. In this paper, a discussion of the procedures for active fire FRP is presented: The Dozier method, the MODIS (Moderate Resolution Imaging Spectroradiometer) fire detection algorithm and semi-empirical relation-ship based on previous studies of BIRD (Bi-spectral InfraRed Detection) satellite. These procedures, described above, are applied to simulated data by a radiative transfer model, based on Sentinel-3/SLSTR spectral characteristics in order to analyze the impact of atmospheric conditions on FRP estimations.

  20. Using Light-at-Night (LAN) Satellite Data for Identifying Clusters of Economic Activities in Europe

    NASA Astrophysics Data System (ADS)

    Rybnikova, N. A.; Portnov, B. A.

    2015-04-01

    Enterprises organized in clusters are often efficient in stimulating urban development, productivity and profit outflows. Identifying clusters of economic activities (EAs) thus becomes an important step in devising regional development policies, aimed at facilitating regional economic development. However, a major problem with cluster identification stems from limited reporting of specific EAs by individual countries and administrative entities. Even Eurostat, which maintains most advances regional databases, provides data for less than 50% of all regional subdivisions of the 3rd tier of the Nomenclature of Territorial Units for Statistics (NUTS3). Such poor reporting impedes identification of EA clusters and economic forces behind them. In this study, we test a possibility that missing data on geographic concentrations of EAs can be reconstructed using Light-at-Night (LAN) satellite measurements, and that such reconstructed data can then be used for the identification of EA clusters. As we hypothesize, LAN, captured by satellite sensors, is characterized by different intensity, depending on its source - production facilities, services, etc., - and this information can be used for EA identification. The study was carried out in three stages. First, using nighttime satellite images, we determined what types of EAs can be identified, with a sufficient degree of accuracy, by LAN they emit. Second, we calculated multivariate statistical models, linking EAs concentrations with LAN intensities and several locational and development attributes of NUTS3 regions in Europe. Next, using the obtained statistical models, we restored missing data on EAs across NUTS3 regions in Europe and identified clusters of EAs, using spatial analysis tools.

  1. Heat shock factor 1 binds to and transcribes satellite II and III sequences at several pericentromeric regions in heat-shocked cells

    SciTech Connect

    Eymery, Angeline; Souchier, Catherine; Vourc'h, Claire; Jolly, Caroline

    2010-07-01

    Cells respond to stress by activating the synthesis of heat shock proteins (HSPs) which protect the cells against the deleterious effects of stress. This mechanism is controlled by the heat shock factor 1 (HSF1). In parallel to HSP gene transcription, in human cells, HSF1 also binds to and transcribes satellite III repeated sequences present in numerous copies in the 9q12 pericentromeric region of chromosome 9. These HSF1 accumulation sites are termed nuclear stress bodies (nSBs). In tumor cells, however, the number of nSBs is higher than the number of 9q12 copies, suggesting the existence of other HSF1 targets. In this paper, we were interested in characterizing these other HSF1 binding sites. We show that HSF1 indeed binds to the pericentromeric region of 14 chromosomes, thereby directing the formation of 'secondary nSBs'. The appearance of secondary nSBs depends on the number of satellite sequences present in the target locus, and on the cellular amount of HSF1 protein. Moreover, secondary nSBs also correspond to transcription sites, thus demonstrating that heat shock induces a genome-wide transcription of satellite sequences. Finally, by analyzing published transcriptomic data, we show that the derepression of these large heterochromatic blocks does not significantly affect the transcription of neighboring genes.

  2. Dynamic elastic behavior of alpha-satellite DNA domains visualized in situ in living human cells

    PubMed Central

    1996-01-01

    We have constructed a fluorescent alpha-satellite DNA-binding protein to explore the motile and mechanical properties of human centromeres. A fusion protein consisting of human CENP-B coupled to the green fluorescent protein (GFP) of A. victoria specifically targets to centromeres when expressed in human cells. Morphometric analysis revealed that the alpha-satellite DNA domain bound by CENPB-GFP becomes elongated in mitosis in a microtubule-dependent fashion. Time lapse confocal microscopy in live mitotic cells revealed apparent elastic deformations of the central domain of the centromere that occurred during metaphase chromosome oscillations. These observations demonstrate that the interior region of the centromere behaves as an elastic element that could play a role in the mechanoregulatory mechanisms recently identified at centromeres. Fluorescent labeling of centromeres revealed that they disperse throughout the nucleus in a nearly isometric expansion during chromosome decondensation in telophase and early G1. During interphase, centromeres were primarily stationary, although motility of individual or small groups of centromeres was occasionally observed at very slow rates of 7-10 microns/h. PMID:8909532

  3. Earth-satellite path attenuation statistics influenced by orientation of rain cells

    NASA Technical Reports Server (NTRS)

    Goldhirsh, J.

    1977-01-01

    It is examined whether there may be preferred azimuths for earth-satellite paths along which fading and space diversity statistics are influenced differently than along other azimuths. Such preferred directions may exist if individual rain cells are statistically elongated along them for the given climatological region. The analysis is performed using the rain reflectivity data base obtained at Wallops Island during June, July and August 1973 using a high resolution radar. It is found that in the vicinity of Wallops Island increased attenuation and poorer diversity gains exist along paths whose azimuths and base lines lie in the NE-SW quadrants as compared to the NW-SE sectors. This result suggests the dominance of the major axis of rain cells in these quadrants.

  4. The role of radiation hard solar cells in minimizing the costs of global satellite communication systems

    NASA Technical Reports Server (NTRS)

    Summers, Geoffrey P.; Walters, Robert J.; Messenger, Scott R.; Burke, Edward A.

    1996-01-01

    An analysis embodied in a PC computer program is presented, which quantitatively demonstrates how the availability of radiation hard solar cells can help minimize the cost of a global satellite communications system. An important distinction between the currently proposed systems, such as Iridium, Odyssey and Ellipsat, is the number of satellites employed and their operating altitudes. Analysis of the major costs associated with implementing these systems shows that operation at orbital altitudes within the earth's radiation belts (10(exp 3) to 10(exp 4)km) can reduce the total cost of a system by several hundred percent, so long as radiation hard components including solar cells can be used. A detailed evaluation of the predicted performance of photovoltaic arrays using several different planar solar cell technologies is given, including commercially available Si and GaAs/Ge, and InP/Si which is currently under development. Several examples of applying the program are given, which show that the end of life (EOL) power density of different technologies can vary by a factor of ten for certain missions. Therefore, although a relatively radiation-soft technology can usually provide the required EOL power by simply increasing the size of the array, the impact upon the total system budget could be unacceptable, due to increased launch and hardware costs. In aggregate, these factors can account for more than a 10% increase in the total system cost. Since the estimated total costs of proposed global-coverage systems range from $1B to $9B, the availability of radiation-hard solar cells could make a decisive difference in the selection of a particular constellation architecture.

  5. Satellites of Xe transitions induced by infrared active vibrational modes of CF4 and C2F6 molecules.

    PubMed

    Alekseev, Vadim A; Schwentner, Nikolaus

    2011-07-28

    Absorption and luminescence excitation spectra of Xe/CF(4) mixtures were studied in the vacuum UV region at high resolution using tunable synchrotron radiation. Pressure-broadened resonance bands and bands associated with dipole-forbidden states of the Xe atom due to collision-induced breakdown of the optical selection rules are reported. The spectra display in addition numerous satellite bands corresponding to transitions to vibrationally excited states of a Xe-CF(4) collisional complex. These satellites are located at energies of Xe atom transition increased by one quantum energy in the IR active v(3) vibrational mode of CF(4) (v(3) = 1281 cm(-1)). Satellites of both resonance and dipole-forbidden transitions were observed. Satellites of low lying resonance states are spectrally broad bands closely resembling in shape their parent pressure-broadened resonance bands. In contrast, satellites of dipole-forbidden states and of high lying resonance states are spectrally narrow bands (FWHM ∼10 cm(-1)). The satellites of dipole-forbidden states are orders of magnitude stronger than transitions to their parent states due to collision-induced breakdown of the optical selection rules. These satellites are attributed to a coupling of dipole-forbidden and resonance states induced by the electric field of the transient CF(4) (v(3) = 0 ↔ v(3) = 1) dipole. Similar satellites are present in spectra of Xe/C(2)F(6) mixtures where these bands are induced by the IR active v(10) mode of C(2)F(6). Transitions to vibrationally excited states of Xe-CF(4)(C(2)F(6)) collision pairs were also observed in two-photon LIF spectra.

  6. Retrievals of Falling Snow from Satellite-borne Active and Passive Sensors

    NASA Astrophysics Data System (ADS)

    Jackson, Gail; Munchak, S. Joseph; Johnson, Benjamin

    2014-05-01

    Precipitation, including rain and snow, is a critical part of the Earth's energy and hydrology cycles. Precipitation impacts latent heating profiles locally while global circulation patterns distribute precipitation and energy from the equator to the poles. For the hydrological cycle, falling snow is a primary contributor in northern latitudes during the winter seasons. Falling snow is the source of snow pack accumulations that provide fresh water resources for many communities in the world. Furthermore, falling snow impacts society by causing transportation disruptions during severe snow events. In order to collect information on the complete global precipitation cycle, both liquid and frozen precipitation must be collected. The Global Precipitation Measurement (GPM) mission's Core satellite, scheduled for launch in February 2014, is well designed to detect and estimate falling snow. The GPM core carries a passive radiometer with frequencies (10-183 GHz) and an active radar with Ku- and Ka-band frequencies. Combined with the 65o inclination of the GPM Core satellite, these instruments allow for the GPM Core to sense and retrieve information about falling snow and light rain in regions of the earth where snow is common. The GPM Core's comprehensive active and passive channel set will also allow it to serve as a unifying reference for GPM constellation radiometer satellites. Since falling snow from space is the next precipitation measurement challenge from space, information is needed to guide retrieval algorithm development for these current and future missions. This information includes thresholds of detection for various sensor channel configurations, sensitivity to macroscale snow event system characteristics, and sensitivity to microscale snowflake particle characteristics. While the work in this area will continue for many years to come, our group has made substantial progress in this area by identifying minimum detectable melted rates of ~0.5 mm hr-1. Results

  7. Retrievals of Falling Snow from Satellite-borne Active and Passive Sensors

    NASA Astrophysics Data System (ADS)

    Skofronick-Jackson, Gail; Munchak, S. Joseph; Johnson, Benjamin

    2013-04-01

    Precipitation, including rain and snow, is a critical part of the Earth's energy and hydrology cycles. Precipitation impacts latent heating profiles locally while global circulation patterns distribute precipitation and energy from the equator to the poles. For the hydrological cycle, falling snow is a primary contributor in northern latitudes during the winter seasons. Falling snow is the source of snow pack accumulations that provide fresh water resources for many communities in the world. Furthermore, falling snow impacts society by causing transportation disruptions during severe snow events. In order to collect information on the complete global precipitation cycle, both liquid and frozen precipitation must be collected. The Global Precipitation Measurement (GPM) mission's Core satellite, scheduled for launch in 2014, is well designed to detect and estimate falling snow. The GPM core carries a passive radiometer with frequencies (10-183 GHz) and an active radar with Ku- and Ka-band frequencies. Combined with the 65 degree inclination of the GPM Core satellite, these instruments allow for the GPM Core to sense and retrieve information about falling snow and light rain in regions of the earth where snow is common. The GPM Core's comprehensive active and passive channel set will also allow it to serve as a unifying reference for GPM constellation radiometer satellites. Since falling snow from space is the next precipitation measurement challenge from space, information is needed to guide retrieval algorithm development for these current and future missions. This information includes thresholds of detection for various sensor channel configurations, sensitivity to macroscale snow event system characteristics, and sensitivity to microscale snowflake particle characteristics. While the work in this area will continue for many years to come, our group has made substantial progress in this area by identifying minimum detectable melted rates of ~0.5 mm/hr. Results will

  8. Satellite glial cells in sympathetic and parasympathetic ganglia: in search of function.

    PubMed

    Hanani, Menachem

    2010-09-24

    Glial cells are established as essential for many functions of the central nervous system, and this seems to hold also for glial cells in the peripheral nervous system. The main type of glial cells in most types of peripheral ganglia - sensory, sympathetic, and parasympathetic - is satellite glial cells (SGCs). These cells usually form envelopes around single neurons, which create a distinct functional unit consisting of a neuron and its attending SGCs. This review presents the knowledge on the morphology of SGCs in sympathetic and parasympathetic ganglia, and the (limited) available information on their physiology and pharmacology. It appears that SGCs carry receptors for ATP and can thus respond to the release of this neurotransmitter by the neurons. There is evidence that SGCs have an uptake mechanism for GABA, and possibly other neurotransmitters, which enables them to control the neuronal microenvironment. Damage to post- or preganglionic nerve fibers influences both the ganglionic neurons and the SGCs. One major consequence of postganglionic nerve section is the detachment of preganglionic nerve terminals, resulting in decline of synaptic transmission. It appears that, at least in sympathetic ganglia, SGCs participate in the detachment process, and possibly in the subsequent recovery of the synaptic connections. Unlike sensory neurons, neurons in autonomic ganglia receive synaptic inputs, and SGCs are in very close contact with synaptic boutons. This places the SGCs in a position to influence synaptic transmission and information processing in autonomic ganglia, but this topic requires much further work.

  9. Relaxin regulates MMP expression and promotes satellite cell mobilization during muscle healing in both young and aged mice.

    PubMed

    Mu, Xiaodong; Urso, Maria L; Murray, Kiley; Fu, Freddie; Li, Yong

    2010-11-01

    The polypeptide hormone relaxin has been proven to be effective in promoting both the remodeling and regeneration of various tissues, including cardiac muscle. In addition, our previous study demonstrated that relaxin is beneficial to skeletal muscle healing by both promoting muscle regeneration and preventing fibrosis formation. However, the molecular and cellular mechanisms of relaxin in regulating both myogenic cell differentiation and muscle healing process are still unclear. In this study, C2C12 mouse myoblasts and primary human myoblasts were treated with relaxin to investigate its potential effect in vitro; relaxin was also injected intramuscularly into the injured site of the mouse on the second day after injury to observe its function in vivo, especially in the aged muscle. Results showed that relaxin promoted myogenic differentiation, migration, and activation of matrix metalloproteinases (MMPs) of cultured myoblasts in vitro. In the injured muscle, relaxin administration promoted the activation of Pax7-positive skeletal muscle satellite cells and increased its local population compared with nontreated control muscles. Meanwhile, both angiogenesis and revascularization were increased, while the extended inflammatory reaction was repressed in the relaxin-treated injured muscle. Moreover, relaxin similarly promoted muscle healing in mice with aged muscle. These results revealed the multiple effects of relaxin in systematically improving muscle healing as well as its potential for clinical applications in patients with skeletal muscle injuries and diseases.

  10. Seismic and satellite observations of calving activity at major glacier fronts in Greenland

    NASA Astrophysics Data System (ADS)

    Danesi, Stefania; Salimbeni, Simone; Urbini, Stefano; Pondrelli, Silvia; Margheriti, Lucia

    2016-04-01

    The interaction between oceans and large outlet glaciers in polar regions contributes to the budget of the global water cycle. We have observed the dynamic of sizeable outlet glaciers in Greenland by the analysis of seismic data collected by the regional seismic network Greenland Ice Sheet Monitoring Network (GLISN) trying also to find out correspondence in the glacier tongue evolution derived by the observation of satellite images. By studying the long-period seismic signals at stations located at the mouth of large fjords (e.g. ILULI, NUUG, KULLO), we identify major calving events through the detection of the ground flexure in response to seiche waves generated by iceberg detachments. 
For the time spanning the period between 2010-2014, we fill out calving-event catalogues which can be useful for the estimation of spatial and temporal variations in volume of ice loss at major active fronts in Greenland.

  11. Capturing the fingerprint of Etna volcano activity in gravity and satellite radar data.

    PubMed

    Del Negro, Ciro; Currenti, Gilda; Solaro, Giuseppe; Greco, Filippo; Pepe, Antonio; Napoli, Rosalba; Pepe, Susi; Casu, Francesco; Sansosti, Eugenio

    2013-10-30

    Long-term and high temporal resolution gravity and deformation data move us toward a better understanding of the behavior of Mt Etna during the June 1995 - December 2011 period in which the volcano exhibited magma charging phases, flank eruptions and summit crater activity. Monthly repeated gravity measurements were coupled with deformation time series using the Differential Synthetic Aperture Radar Interferometry (DInSAR) technique on two sequences of interferograms from ERS/ENVISAT and COSMO-SkyMed satellites. Combining spatiotemporal gravity and DInSAR observations provides the signature of three underlying processes at Etna: (i) magma accumulation in intermediate storage zones, (ii) magmatic intrusions at shallow depth in the South Rift area, and (iii) the seaward sliding of the volcano's eastern flank. Here we demonstrate the strength of the complementary gravity and DInSAR analysis in discerning among different processes and, thus, in detecting deep magma uprising in months to years before the onset of a new Etna eruption.

  12. ESA activities on satellite laser ranging to non-cooperative objects

    NASA Astrophysics Data System (ADS)

    Flohrer, Tim; Krag, Holger; Funke, Quirin; Jilete, Beatriz; Mancas, Alexandru

    2016-07-01

    Satellite laser ranging (SLR) to non-cooperative objects is an emerging technology that can contribute significantly to operational, modelling and mitigation needs set by the space debris population. ESA is conducting various research and development activities in SLR to non-cooperative objects. ESA's Space Situational Awareness (SSA) program supports specific activities in the Space Surveillance and Tracking (SST) segment. Research and development activities with operational aspects are run by ESA's Space Debris Office. At ESA SSA/SST comprises detecting, cataloguing and predicting the objects orbiting the Earth, and the derived applications. SST aims at facilitating research and development of sensor and data processing technologies and of related common components while staying complementary with, and in support of, national and multi-national European initiatives. SST promotes standardisation and interoperability of the technology developments. For SLR these goals are implemented through researching, developing, and deploying an expert centre. This centre shall coordinate the contribution of system-external loosely connected SLR sensors, and shall provide back calibration and expert evaluation support to the sensors. The Space Debris Office at ESA is responsible for all aspects related to space debris in the Agency. It is in charge of providing operational support to ESA and third party missions. Currently, the office studies the potential benefits of laser ranging to space debris objects to resolve close approaches to active satellites, to improve re-entry predictions of time and locations, and the more general SLR support during contingency situations. The office studies the determination of attitude and attitude motion of uncooperative objects with special focus on the combination of SLR, light-curve, and radar imaging data. Generating sufficiently precise information to allow for the acquisition of debris objects by a SLR sensor in a stare

  13. Internet-Based Laboratory Activities Designed for Studying the Sun with Satellites

    NASA Astrophysics Data System (ADS)

    Slater, T. F.

    1998-12-01

    Yohkoh Public Outreach Project (YPOP) is a collaborative industry, university, and K-16 project bringing fascinating and dynamic images of the Sun to the public in real-time. Partners have developed an extensive public access and educational WWW site containing more than 100 pages of vibrant images with current information that focuses on movies of the X-ray output of our Sun taken by the Yohkoh Satellite. More than 5 Gb of images and movies are available on the WWW site from the Yohkoh satellite, a joint project of the Institute for Space and Astronautical Sciences (ISAS) and NASA. Using a movie theater motif, the site was created by teams working at Lockheed Martin Advanced Technology Center, Palo Alto, CA in the Solar and Astrophysics Research Group, the Montana State University Solar Physics Research Group, and the Montana State University Conceptual Astronomy and Physics Education Research Group with funding from the NASA Learning Technology Project (LTP) program (NASA LTP SK30G4410R). The Yohkoh Movie Theater Internet Site is found at URL: http://www.lmsal.com/YPOP/ and mirrored at URL: http://solar.physics.montana.edu/YPOP/. In addition to being able to request automated movies for any dates in a 5 Gb on-line database, the user can view automatically updated daily images and movies of our Sun over the last 72 hours. Master science teachers working with the NASA funded Yohkoh Public Outreach Project have developed nine technology-based on-line lessons for K-16 classrooms. These interdisciplinary science, mathematics, and technology lessons integrate Internet resources, real-time images of the Sun, and extensive NASA image databases. Instructors are able to freely access each of the classroom-ready activities. The activities require students to use scientific inquiry skills and manage electronic information to solve problems consistent with the emphasis of the NRC National Science Education Standards.

  14. Evaluation of the effect of static magnetic fields combined with human hepatocyte growth factor on human satellite cell cultures.

    PubMed

    Birk, Richard; Sommer, Ulrich; Faber, Anne; Aderhold, Christoph; Schulz, Johannes D; Hörmann, Karl; Goessler, Ulrich Reinhart; Stern-Straeter, Jens

    2014-06-01

    Tissue engineering is a promising research field, which aims to create new functional muscle tissue in vitro, by utilizing the myogenic differentiation potential of human stem cells. The objective of the present study was to determine the effect of static magnetic fields (SMF), combined with the use of the myogenic differentiation enhancing hepatocyte growth factor (HGF), on human satellite cell cultures, which are one of the preferred stem cell sources in skeletal muscle tissue engineering. We performed almarBlue® proliferation assays and semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) for the following myogenic markers: desmin (DES), myogenic factor 5 (MYF5), myogenic differentiation antigen 1 (MYOD1), myogenin (MYOG), myosin heavy chain (MYH) and α1 actin (ACTA1) to detect the effects on myogenic maturation. Additionally, immunohistochemical staining (ICC) and fusion index (FI) determination as independent markers of differentiation were performed on satellite cell cultures stimulated with HGF and HGF + SMF with an intensity of 80 mT. ICC verified the muscle phenotype at all time points. SMF enhanced the proliferation of satellite cell cultures treated with HGF. RT-PCR analysis, ICC and FI calculation revealed the effects of HGF/SMF on the investigated differentiation markers and stimulation with HGF and SMF verified the continuing maturation, however no significant increase in analysed markers could be detected when compared with control cultures treated with serum cessation. In conclusion, HGF or HGF + SMF stimulation of human satellite cell cultures did not lead to the desired enhancement of myogenic maturation of human satellite cell cultures compared with cell cultures stimulated with growth factor reduction.

  15. Micro space power system using MEMS fuel cell for nano-satellites

    NASA Astrophysics Data System (ADS)

    Lee, Jongkwang; Kim, Taegyu

    2014-08-01

    A micro space power system using micro fuel cell was developed for nano-satellites. The power system was fabricated using microelectromechanical system (MEMS) fabrication technologies. Polymer electrolyte membrane (PEM) fuel cell was selected in consideration of space environment. Sodium borohydride (NaBH4) was selected as a hydrogen source while hydrogen peroxide (H2O2) was selected as an oxygen source. The power system consists of a micro fuel cell, micro-reactor, micro-pump, and fuel cartridges. The micro fuel cell was fabricated on a light-weight and corrosion-resistant glass plates. The micro-reactor was used to generate hydrogen from NaBH4 alkaline solution via a catalytic hydrolysis reaction. All components such as micro-pump, fuel cartridges, and auxiliary battery were integrated for a complete power system. The storability of NaBH4 solution was evaluated at -25 °C and the performance of the micro power system was measured at various operating conditions. The power output of micro power system reasonably followed up the given electric load conditions.

  16. Do the Purkinje cells have a special type of oligodendrocyte as satellites?

    PubMed Central

    Monteiro, R A

    1983-01-01

    Two types of oligodendrocytes considered to be a constant feature in the cerebellar cortex of the rat are described. One cell type (I) exhibits rounded or elliptical nuclei, whereas the other type (II) presents more irregular nuclear and cellular contours and wider perinuclear cisternae. The latter cell type shows a more electron-dense cytoplasm with more heavily clumped heterochromatin, contrasting strongly with the euchromatin; also long and parallel cisternae of rough endoplasmic reticulum are more frequent. The percentages of both types of oligodendrocytes in relation to the total population of common glial cell types were calculated in the cortical layers and at several levels in these layers. The distribution of oligodendrocytes in the associated white matter was also carried out for purposes of comparison. The results provide evidence the the Purkinje cells may have a special kind of oligodendrocyte (Type II) as satellites. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 PMID:6630036

  17. Gravitational mechanism of active life of the Earth, planets and satellites

    NASA Astrophysics Data System (ADS)

    Barkin, Yury

    2010-05-01

    From positions of geodynamic model of the forced gravitational swing, wobble and displacements of shells of a planet are studied and fundamental problems of geodynamics, geology, geophysics, planetary sciences are solved etc.: 1) The mechanism of cyclic variations of activity of natural processes in various time scales. 2) The power of endogenous activity of planetary natural processes on planets and satellites. 3) The phenomenon of polar inversion of natural processes on planets and satellites. 4) Spasmodic and catastrophic changes of activity of natural processes. 5) The phenomenon of twisting of hemispheres (latitude zones or belts) of celestial bodies. 6) Formation of the pear-shaped form of celestial bodies and the mechanism of its change. 7) The ordered planetary structures of geological formations. 8) The phenomena of bipolarity of celestial bodies and antipodality of geology formations. Mechanism. The fundamental feature of a structure of celestial bodies is their shell structure. The most investigated is the internal structure of the Earth. For the Moon and wide set of other bodies of solar system models of an internal structure have been constructed on the basis of the data of observations obtained at studying of their gravitational fields as a result of realization of the appropriate space missions. The basic components for the majority of celestial bodies are the core, the mantle and the crust. To other shells we concern atmospheres (for example, at Venus, Mars, the Titan etc.) and oceanic shells (the Titan, the Earth, Enceladus etc.). Shells are the complex (composite) formations. Planets and satellites are not spherical celestial bodies. The centers of mass of shells of the given planet (or the satellite) and their appropriate principal axes of inertia do not coincide. Accordingly, all their shells are characterized by the certain dynamic oblatenesses. Differences of dynamical oblatenesses results in various forced influences of external celestial

  18. Management and climate contributions to satellite-derived active fire trends in the contiguous United States.

    PubMed

    Lin, Hsiao-Wen; McCarty, Jessica L; Wang, Dongdong; Rogers, Brendan M; Morton, Douglas C; Collatz, G James; Jin, Yufang; Randerson, James T

    2014-04-01

    Fires in croplands, plantations, and rangelands contribute significantly to fire emissions in the United States, yet are often overshadowed by wildland fires in efforts to develop inventories or estimate responses to climate change. Here we quantified decadal trends, interannual variability, and seasonality of Terra Moderate Resolution Imaging Spectroradiometer (MODIS) observations of active fires (thermal anomalies) as a function of management type in the contiguous U.S. during 2001-2010. We used the Monitoring Trends in Burn Severity database to identify active fires within the perimeter of large wildland fires and land cover maps to identify active fires in croplands. A third class of fires defined as prescribed/other included all residual satellite active fire detections. Large wildland fires were the most variable of all three fire types and had no significant annual trend in the contiguous U.S. during 2001-2010. Active fires in croplands, in contrast, increased at a rate of 3.4% per year. Cropland and prescribed/other fire types combined were responsible for 77% of the total active fire detections within the U.S and were most abundant in the south and southeast. In the west, cropland active fires decreased at a rate of 5.9% per year, likely in response to intensive air quality policies. Potential evaporation was a dominant regulator of the interannual variability of large wildland fires, but had a weaker influence on the other two fire types. Our analysis suggests it may be possible to modify landscape fire emissions within the U.S. by influencing the way fires are used in managed ecosystems.

  19. Management and climate contributions to satellite-derived active fire trends in the contiguous United States

    PubMed Central

    Lin, Hsiao-Wen; McCarty, Jessica L; Wang, Dongdong; Rogers, Brendan M; Morton, Douglas C; Collatz, G James; Jin, Yufang; Randerson, James T

    2014-01-01

    Fires in croplands, plantations, and rangelands contribute significantly to fire emissions in the United States, yet are often overshadowed by wildland fires in efforts to develop inventories or estimate responses to climate change. Here we quantified decadal trends, interannual variability, and seasonality of Terra Moderate Resolution Imaging Spectroradiometer (MODIS) observations of active fires (thermal anomalies) as a function of management type in the contiguous U.S. during 2001–2010. We used the Monitoring Trends in Burn Severity database to identify active fires within the perimeter of large wildland fires and land cover maps to identify active fires in croplands. A third class of fires defined as prescribed/other included all residual satellite active fire detections. Large wildland fires were the most variable of all three fire types and had no significant annual trend in the contiguous U.S. during 2001–2010. Active fires in croplands, in contrast, increased at a rate of 3.4% per year. Cropland and prescribed/other fire types combined were responsible for 77% of the total active fire detections within the U.S and were most abundant in the south and southeast. In the west, cropland active fires decreased at a rate of 5.9% per year, likely in response to intensive air quality policies. Potential evaporation was a dominant regulator of the interannual variability of large wildland fires, but had a weaker influence on the other two fire types. Our analysis suggests it may be possible to modify landscape fire emissions within the U.S. by influencing the way fires are used in managed ecosystems. Key Points Wildland, cropland, and prescribed fires had different trends and patterns Sensitivity to climate varied with fire type Intensity of air quality regulation influenced cropland burning trends PMID:26213662

  20. Theoretical Model of Drag Force Impact on a Model International Space Station (ISS) Satellite due to Solar Activity

    NASA Astrophysics Data System (ADS)

    Nwankwo, Victor U. J.; Chakrabarti, Sandip Kumar

    The International Space Station (ISS) is the single largest and most complex scientific and engineering space structure in human history. Its orbital parameters make it extremely vulnerable to severe atmospheric drag force. Complex interactions between solar energetic particles, ultraviolet (UV) radiation with atmosphere and geomagnetic field cause heating and subsequent expansion of the upper atmosphere. This condition increases drag on low Earth orbit satellites (LEOSs) and varies with current space weather conditions. In this work, we apply the NRLMSISE-00 empirical atmospheric density model, as a function of space environmental parameters, to model drag force impact on a model LEOS during variation of solar activity. Applying the resulting drag model on a model ISS satellite we observe that depending on the severity and/or stage of solar activity or cycle, a massive artificial satellite could experience orbit decay rate of up to 2.95km/month during solar maximum and up to 1km/month during solar minimum.

  1. A method for the integration of satellite vegetation activities observations and magnetic susceptibility measurements for monitoring heavy metals in soil.

    PubMed

    D'Emilio, Mariagrazia; Macchiato, Maria; Ragosta, Maria; Simoniello, Tiziana

    2012-11-30

    We present a procedure for monitoring heavy metals in soil based on the integration of satellite and ground-based techniques, tested in an area affected by high anthropogenic pressure. High resolution multispectral satellite data were elaborated to obtain information on vegetation status. Magnetic susceptibility measurements of soils were collected as proxy variable for monitoring heavy metal presence. Chemical analyses of heavy metals were used for supporting and validating the integrated monitoring procedure. Magnetic and chemical measurements were organized in a GIS environment to be overlapped to satellite-based elaborations and to analyze the pattern distribution. Results show the presence of correlation between anomalies in vegetation activity and soil characteristics. The relationship between the distribution of normalized difference vegetation index anomalies and magnetic susceptibility values provides hints for adopting the integrated procedure as preliminary screening to minimize monitoring efforts and costs by supporting the planning activities of field campaigns.

  2. Sequence-specific microscopic visualization of DNA methylation status at satellite repeats in individual cell nuclei and chromosomes.

    PubMed

    Li, Yufeng; Miyanari, Yusuke; Shirane, Kenjiro; Nitta, Hirohisa; Kubota, Takeo; Ohashi, Hirofumi; Okamoto, Akimitsu; Sasaki, Hiroyuki

    2013-10-01

    Methylation-specific fluorescence in situ hybridization (MeFISH) was developed for microscopic visualization of DNA methylation status at specific repeat sequences in individual cells. MeFISH is based on the differential reactivity of 5-methylcytosine and cytosine in target DNA for interstrand complex formation with osmium and bipyridine-containing nucleic acids (ICON). Cell nuclei and chromosomes hybridized with fluorescence-labeled ICON probes for mouse major and minor satellite repeats were treated with osmium for crosslinking. After denaturation, fluorescent signals were retained specifically at satellite repeats in wild-type, but not in DNA methyltransferase triple-knockout (negative control) mouse embryonic stem cells. Moreover, using MeFISH, we successfully detected hypomethylated satellite repeats in cells from patients with immunodeficiency, centromeric instability and facial anomalies syndrome and 5-hydroxymethylated satellite repeats in male germ cells, the latter of which had been considered to be unmethylated based on anti-5-methylcytosine antibody staining. MeFISH will be suitable for a wide range of applications in epigenetics research and medical diagnosis.

  3. Implication of the satellite cell in dystrophic muscle fibrosis: a self-perpetuating mechanism of collagen overproduction.

    PubMed

    Alexakis, Catherine; Partridge, Terence; Bou-Gharios, George

    2007-08-01

    Because of its mechanical function, skeletal muscle is heavily influenced by the composition of its extracellular matrix (ECM). Fibrosis generated by chronic damage, such as occurs in muscular dystrophies, is thus particularly disastrous in this tissue. Here, we examined the interrelationship between the muscle satellite cell and the production of collagen type I, a major component of fibrotic ECM, by using both C2C12, a satellite cell-derived cell line, and primary muscle satellite cells. In C2C12 cells, we found that expression of collagen type I mRNA decreases substantially during skeletal muscle differentiation. On a single-cell level, collagen type I and myogenin became mutually exclusive after 3 days in differentiation medium, whereas addition of collagen markedly suppressed differentiation of C2C12 cells. Primary cultures of satellite cells associated with isolated single fibers of the young (4 wk old) mdx dystrophic mouse and of C57BL/10ScSn wild-type controls expressed collagen type I and type III mRNA and protein. This pattern persisted in wild-type mice at all ages. But, curiously, in older (18-mo-old) mdx mice, although the myogenic cells continued to express type III collagen, type I expression became restricted to nonmyogenic cells. These cells typically constituted part of a cellular sheet surrounding the old mdx fibers. This combination of features strongly suggests that the progression to fibrosis in dystrophic muscle involves changes in the mechanisms controlling matrix production, which generates positive feedback that results in a reprogramming of myoblasts to a profibrotic function.

  4. Injection of duck recombinant follistatin fusion protein into duck muscle tissues stimulates satellite cell proliferation and muscle fiber hypertrophy.

    PubMed

    Liu, He-he; Wang, Ji-wen; Yu, Hai-yue; Zhang, Rong-ping; Chen, Xi; Jin, Hai-bo; Dai, Fei; Li, Liang; Xu, Feng

    2012-06-01

    Follistatin (FST) can inhibit the expression of myostatin, which is a predominant inhibitor of muscle development. The potential application of myostatin-based technology has been prompted in different ways in agriculture. We previously constructed an expression vector of duck FST and isolated the FST fusion protein. After the protein was purified and refolded, it was added to the medium of duck myoblasts cultured in vitro. The results show that the 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide value of the myoblasts in the duck FST treatment group is higher than that in the control group, which indicates that the duck FST fusion protein exhibits the biological activities that can accelerate myoblast proliferation. To further investigate the roles of duck FST on muscle development, we injected the protein into the duck muscle tissues in vivo. The results show that both the duck muscle fiber cross-sectional area and the satellite cell activation frequency are influenced more in the FST treatment group than they are in the control group. In addition to these phenomena, expression of MyoD and Myf5 were increased, and the expression of myostatin was decreased. Together, these results suggest the potential for using duck FST fusion protein to inhibit myostatin activity and subsequently to enhance muscle growth in vivo. The mechanism by which FST regulates muscle development in the duck is similar to that in mammals and fishes.

  5. Analytic studies on satellite detection of severe, two-cell tornadoes

    NASA Technical Reports Server (NTRS)

    Carrier, G. F.; Dergarabedian, P.; Fendell, F. E.

    1979-01-01

    From funnel-cloud-length interpretation, the severe tornado is characterized by peak swirl speed relative to the axis of rotation of about 90 m/s. Thermohydrodynamic achievement of the pressure deficit from ambient necessary to sustain such swirls requires that a dry, compressionally heated, non-rotating downdraft of initially tropopause-level air lie within an annulus of rapidly swirling, originally low-level air ascending on a near-moist-adiabatic locus of thermodynamic states. The two-cell structure furnishes an observable parameter possibly accessible to a passively instrumented, geosynchronous meteorological satellite with mesoscale resolution, for early detection of a severe tornado. Accordingly, the low-level turnaround region, in which the surface inflow layer separates to become a free ascending layer and for which inviscid modeling suffices, is examined quantitatively. Preliminary results indicate that swirl overshoot, i.e., swirl speeds in the turnaround region in excess of the maximum achieved in the potential vortex, is modest.

  6. The quasi-parallel lives of satellite cells and atrophying muscle

    PubMed Central

    Biressi, Stefano; Gopinath, Suchitra D.

    2015-01-01

    Skeletal muscle atrophy or wasting accompanies various chronic illnesses and the aging process, thereby reducing muscle function. One of the most important components contributing to effective muscle repair in postnatal organisms, the satellite cells (SCs), have recently become the focus of several studies examining factors participating in the atrophic process. We critically examine here the experimental evidence linking SC function with muscle loss in connection with various diseases as well as aging, and in the subsequent recovery process. Several recent reports have investigated the changes in SCs in terms of their differentiation and proliferative capacity in response to various atrophic stimuli. In this regard, we review the molecular changes within SCs that contribute to their dysfunctional status in atrophy, with the intention of shedding light on novel potential pharmacological targets to counteract the loss of muscle mass. PMID:26257645

  7. Patterns of fire activity over Indonesia and Malaysia from polar and geostationary satellite observations

    NASA Astrophysics Data System (ADS)

    Hyer, Edward J.; Reid, Jeffrey S.; Prins, Elaine M.; Hoffman, Jay P.; Schmidt, Christopher C.; Miettinen, Jukka I.; Giglio, Louis

    2013-03-01

    Biomass burning patterns over the Maritime Continent of Southeast Asia are examined using a new active fire detection product based on application of the Wildfire Automated Biomass Burning Algorithm (WF_ABBA) to data from the imagers on the MTSAT geostationary satellites operated by the Japanese space agency JAXA. Data from MTSAT-1R and MTSAT-2 covering 34 months from September 2008 to July 2011 are examined for a study region consisting of Indonesia, Malaysia, and nearby environs. The spatial and temporal distributions of fires detected in the MTSAT WF_ABBA product are described and compared with active fire observations from MODIS MOD14 data. Land cover distributions for the two instruments are examined using a new 250 m land cover product from the National University of Singapore. The two products show broadly similar patterns of fire activity, land cover distribution of fires, and pixel fire radiative power (FRP). However, the MTSAT WF_ABBA data differ from MOD14 in important ways. Relative to MODIS, the MTSAT WF_ABBA product has lower overall detection efficiency, but more fires detected due to more frequent looks, a greater relative fraction of fires in forest and a lower relative fraction of fires in open areas, and significantly higher single-pixel retrieved FRP. The differences in land cover distribution and FRP between the MTSAT and MODIS products are shown to be qualitatively consistent with expectations based on pixel size and diurnal sampling. The MTSAT WF_ABBA data are used to calculate coverage-corrected diurnal cycles of fire for different regions within the study area. These diurnal cycles are preliminary but demonstrate that the fraction of diurnal fire activity sampled by the two MODIS sensors varies significantly by region and vegetation type. Based on the results from comparison of the two fire products, a series of steps is outlined to account for some of the systematic biases in each of these satellite products in order to produce a

  8. Analysis of Satellite Retreived Active-Passive Merged Soil Moisture Distribution: A Case Study Over India.

    NASA Astrophysics Data System (ADS)

    Chakravorty, A.; Chahar, B. R.; Sharma, O. P.; Dhanya, C. T.

    2014-12-01

    Soil moisture is the source of water for evapotranspiration over the continents and it participates in both energy and water balance of the earth. Soil moisture participates in the energy cycle by managing the partitioning of the energy budget into latent and sensible heat, there by influencing the hydrological cycle. But to better understand the influence of soil moisture on the hydrological cycle, large scale monitoring is required. The objective of this study is to qualitatively analyze the active-passive merged soil moisture distribution, prepared under the ESA_CCI programme, against two AMSR-E soil moisture distributions, AMSR-E/NSIDC (National Snow and Ice Data Center) and AMSR-E/VUA(Virje Universiet Amstradam) and GLDAS_NOAH model simulations. The ESA_CCI soil moisture distribution is also compared with the GPCC monthly precipitation distribution to observe the representativeness of the precipitation seasonality in the satellite retrieved soil moisture. India has been selected as the study area, esp. the Central Indian region, as it has shown to be a soil moisture hot-spot for land-surface atmosphere interaction. The preliminary study show that both ESA_CCI and AMSR-E/VUA soil moisture distributions capture similar seasonal patterns in addition to processes like rainfall events and inter-annual variations. In addition to this it was also observed that the soil moisture distribution of ESA_CCI and AMSR-E/VUA are linearly related to each other for more than 50% of the land points. In case of ESA_CCI and AMSR-E/NSIDC, the soil moisture distributions are able to capture similar seasonal patterns but not the random events and they also do not show a strong linear relationship. We also analyze the effect of topography and vegetation distribution on the error charactristics of the satellite retrieved soil moisture distributions.

  9. Viral Evasion of Natural Killer Cell Activation.

    PubMed

    Ma, Yi; Li, Xiaojuan; Kuang, Ersheng

    2016-04-12

    Natural killer (NK) cells play a key role in antiviral innate defenses because of their abilities to kill infected cells and secrete regulatory cytokines. Additionally, NK cells exhibit adaptive memory-like antigen-specific responses, which represent a novel antiviral NK cell defense mechanism. Viruses have evolved various strategies to evade the recognition and destruction by NK cells through the downregulation of the NK cell activating receptors. Here, we review the recent findings on viral evasion of NK cells via the impairment of NK cell-activating receptors and ligands, which provide new insights on the relationship between NK cells and viral actions during persistent viral infections.

  10. Delay in post-ovariectomy estrogen replacement negates estrogen-induced augmentation of post-exercise muscle satellite cell proliferation.

    PubMed

    Mangan, Gary; Iqbal, Sobia; Hubbard, Andrew; Hamilton, Victoria; Bombardier, Eric; Tiidus, Peter M

    2015-11-01

    This study examined the effects of a delay in post-ovariectomy replacement of 17β-estradiol (estrogen) on the post-exercise proliferation of muscle satellite cells. Nine-week-old, ovariectomized, female Sprague-Dawley rats (n = 64) were distributed among 8 groups based on estrogen status (0.25 mg estrogen pellet or sham), exercise status (90 min run at 17 m·min(-1) and a grade of -13.5° or unexercised), and estrogen replacement ("proximal", estrogen replacement within 2 weeks; or "delayed", estrogen replacement at 11 weeks following ovariectomy). Significant increases in satellite cells were found in the soleus and white gastrocnemius muscle (immunofluorescent colocalization of nuclei with Pax7) 72 h following eccentric exercise (p < 0.05) in all exercised groups. Proximal E2 replacement resulted in a further augmentation of muscle satellite cells in exercised rats (p < 0.05) relative to the delayed estrogen replacement group. Expression of PI3K was unaltered and phosphorylation of Akt relative to total Akt increased following estrogen supplementation and exercise. Exercise alone did not alter the expression levels of Akt. An 11 week delay in post-ovariectomy estrogen replacement negated the augmenting influence seen with proximal (2 week delay) post-ovariectomy estrogen replacement on post-exercise muscle satellite cell proliferation. This effect appears to be independent of the PI3K-Akt signaling pathway.

  11. The soil moisture active passive validation experiment 2012 (SMAPVEX12): pre-launch calibration and validation of the SMAP satellite

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The National Aeronautics and Space Administration (NASA) Soil Moisture Active Passive (SMAP) satellite is scheduled for launch in November 2014. In order to develop robust soil moisture retrieval algorithms that fully exploit the unique capabilities of SMAP, algorithm developers had identified a nee...

  12. A muscle stem cell for every muscle: variability of satellite cell biology among different muscle groups.

    PubMed

    Randolph, Matthew E; Pavlath, Grace K

    2015-01-01

    The human body contains approximately 640 individual skeletal muscles. Despite the fact that all of these muscles are composed of striated muscle tissue, the biology of these muscles and their associated muscle stem cell populations are quite diverse. Skeletal muscles are affected differentially by various muscular dystrophies (MDs), such that certain genetic mutations specifically alter muscle function in only a subset of muscles. Additionally, defective muscle stem cells have been implicated in the pathology of some MDs. The biology of muscle stem cells varies depending on the muscles with which they are associated. Here we review the biology of skeletal muscle stem cell populations of eight different muscle groups. Understanding the biological variation of skeletal muscles and their resident stem cells could provide valuable insight into mechanisms underlying the susceptibility of certain muscles to myopathic disease.

  13. A muscle stem cell for every muscle: variability of satellite cell biology among different muscle groups

    PubMed Central

    Randolph, Matthew E.; Pavlath, Grace K.

    2015-01-01

    The human body contains approximately 640 individual skeletal muscles. Despite the fact that all of these muscles are composed of striated muscle tissue, the biology of these muscles and their associated muscle stem cell populations are quite diverse. Skeletal muscles are affected differentially by various muscular dystrophies (MDs), such that certain genetic mutations specifically alter muscle function in only a subset of muscles. Additionally, defective muscle stem cells have been implicated in the pathology of some MDs. The biology of muscle stem cells varies depending on the muscles with which they are associated. Here we review the biology of skeletal muscle stem cell populations of eight different muscle groups. Understanding the biological variation of skeletal muscles and their resident stem cells could provide valuable insight into mechanisms underlying the susceptibility of certain muscles to myopathic disease. PMID:26500547

  14. Observations and analysis activities of the International Ultraviolet Explorer satellite telescope

    NASA Technical Reports Server (NTRS)

    Shull, J. Michael

    1996-01-01

    The funds from this grant were used to support observations and analysis with the International Ultraviolet Explorer (IUE) satellite telescope. The main area of scientific research concerned the variability analyses of ultraviolet spectra of Active Galactic Nuclei, primarily quasars, Seyfert galaxies, and BL Lacertae objects. The Colorado group included, at various times, the P.I. (J.M. Shull), Research Associate Dr. Rick Edelson, and graduate students Jon Saken, Elise Sachs, and Steve Penton. A portion of the work was also performed by CU undergraduate student Cheong-ming Fu. A major product of the effort was a database of all IUE spectra of active galactic nuclei. This database is being analyzed to obtain spectral indices, line fluxes, and continuum fluxes for over 500 AGN. As a by-product of this project, we implemented a new, improved technique of spectral extraction of IUE spectra, which has been used in several AGN-WATCH campaigns (on the Seyfert galaxy NGC 4151 and on the BL Lac object PKS 2155-304).

  15. Comparison of ground and satellite based measurements of the fraction of photosynthetically active radiation intercepted by tall-grass prairie

    NASA Technical Reports Server (NTRS)

    Demetriades-Shah, T. H.; Kanemasu, E. T.; Flitcroft, I.; Su, H.

    1990-01-01

    The fraction, of photosynthetically active radiation absorbed by vegetation, F sub ipar, is an important requirement for estimating vegetation biomass productivity and related quantities. This was an integral part of a large international effort; the First ISLSCP Field Experiment (FIFE). The main objective of FIFE was to study the effects of vegetation on the land atmosphere interactions and to determine if these interactions can be assessed from satellite spectral measurements. The specific purpose of this experiment was to find out how well measurements of F sub ipar relate to ground, helicopter, and satellite based spectral reflectance measurements. Concurrent measurements of F sub ipar and ground, helicopter, and satellite based measurements were taken at 13 tall grass prairie sites in Kansas. The sites were subjected to various combinations of burning and grazing managements.

  16. Procedures for minimizing the effects of high solar activity on satellite tracking and ephemeris generation

    NASA Technical Reports Server (NTRS)

    Bredvik, Gordon D.

    1990-01-01

    We are currently experiencing a period of high solar radiation combined with wide short-term fluctuations in the radiation. The short-term fluctuations, especially when combined with highly energetic solar flares, can adversely affect the mission of U.S. Space Command's Space Surveillance Center (SSC) which catalogs and tracks the satellites in orbit around the Earth. Rapidly increasing levels of solar electromagnetic and/or particle radiation (solar wind) causes atmospheric warming, which, in turn, causes the upper-most portions of the atmosphere to expand outward, into the regime of low altitude satellites. The increased drag on satellites from this expansion can cause large, unmodeled, in-track displacements, thus undermining the SSC's ability to track and predict satellite position. On 13 March 1989, high solar radiation levels, combined with a high-energy solar flare, caused an exceptional amount of short-term atmospheric warming. The SSC temporarily lost track of over 1300 low altitude satellites--nearly half of the low altitude satellite population. Observational data on satellites that became lost during the days following the 13 March 'solar event' was analyzed and compared with the satellites' last element set prior to the event (referred to as a geomagnetic storm because of the large increase in magnetic flux in the upper atmosphere). The analysis led to a set of procedures for reducing the impact of future geomagnetic storms. These procedures adjust selected software limit parameters in the differential correction of element sets and in the observation association process and must be manually initiated at the onset of a geomagnetic storm. Sensor tasking procedures must be adjusted to ensure that a minimum of four observations per day are received for low altitude satellites. These procedures have been implemented and, thus far, appear to be successful in minimizing the effect of subsequent geomagnetic storms on satellite tracking and ephemeris

  17. The Change Indices of Solar and Geomagnetic Activity and Their Influence on the Dynamics of Drag of Artificial Satellite

    NASA Astrophysics Data System (ADS)

    Komendant, V. H.; Koshkin, N. I.; Ryabov, M. I.; Sukharev, A. L.

    2016-12-01

    The time-frequency and multiple regression analysis of the orbital parameter characterizing the drag of satellites on circular and elliptical orbits with different perigees and orbital inclinations in the atmosphere of the Earth was being conducted in 23-24 cycles of solar activity. Among the factors influencing braking dynamics of satellites were taken: W - Wolf numbers; Sp - the total area of sunspot groups of the northern and southern hemispheres of the Sun, F10.7 - the solar radio flux at 10,7 cm; E - electron flux with energies more than 0,6 MeV è 2 MeV; planetary, high latitude and middle latitude geomagnetic index Ap. In the atmospheric drag dynamics of satellites, the following periods were detected: 6-year, 2.1-year, annual, semi-annual, 27-days, 13- and 11-days. Similar periods are identified in indexes of solar and geomagnetic activity. Dependence of the periods of satellites motion on extremes of solar activities and space weather conditions was conducted.

  18. Tropical Cyclone Activity in the North Atlantic Basin During the Weather Satellite Era, 1960-2014

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    2016-01-01

    This Technical Publication (TP) represents an extension of previous work concerning the tropical cyclone activity in the North Atlantic basin during the weather satellite era, 1960-2014, in particular, that of an article published in The Journal of the Alabama Academy of Science. With the launch of the TIROS-1 polar-orbiting satellite in April 1960, a new era of global weather observation and monitoring began. Prior to this, the conditions of the North Atlantic basin were determined only from ship reports, island reports, and long-range aircraft reconnaissance. Consequently, storms that formed far from land, away from shipping lanes, and beyond the reach of aircraft possibly could be missed altogether, thereby leading to an underestimate of the true number of tropical cyclones forming in the basin. Additionally, new analysis techniques have come into use which sometimes has led to the inclusion of one or more storms at the end of a nominal hurricane season that otherwise would not have been included. In this TP, examined are the yearly (or seasonal) and 10-year moving average (10-year moving average) values of the (1) first storm day (FSD), last storm day (LSD), and length of season (LOS); (2) frequencies of tropical cyclones (by class); (3) average peak 1-minute sustained wind speed () and average lowest pressure (); (4) average genesis location in terms of north latitudinal () and west longitudinal () positions; (5) sum and average power dissipation index (); (6) sum and average accumulated cyclone energy (); (7) sum and average number of storm days (); (8) sum of the number of hurricane days (NHD) and number of major hurricane days (NMHD); (9) net tropical cyclone activity index (NTCA); (10) largest individual storm (LIS) PWS, LP, PDI, ACE, NSD, NHD, NMHD; and (11) number of category 4 and 5 hurricanes (N4/5). Also examined are the December-May (D-M) and June-November (J-N) averages and 10-year moving average values of

  19. Endothelial juxtaposition of distinct adult stem cells activates angiogenesis signaling molecules in endothelial cells.

    PubMed

    Mohammadi, Elham; Nassiri, Seyed Mahdi; Rahbarghazi, Reza; Siavashi, Vahid; Araghi, Atefeh

    2015-12-01

    Efficacy of therapeutic angiogenesis needs a comprehensive understanding of endothelial cell (EC) function and biological factors and cells that interplay with ECs. Stem cells are considered the key components of pro- and anti-angiogenic milieu in a wide variety of physiopathological states, and interactions of EC-stem cells have been the subject of controversy in recent years. In this study, the potential effects of three tissue-specific adult stem cells, namely rat marrow-derived mesenchymal stem cells (rBMSCs), rat adipose-derived stem cells (rADSCs) and rat muscle-derived satellite cells (rSCs), on the endothelial activation of key angiogenic signaling molecules, including VEGF, Ang-2, VEGFR-2, Tie-2, and Tie2-pho, were investigated. Human umbilical vein endothelial cells (HUVECs) and rat lung microvascular endothelial cells (RLMECs) were cocultured with the stem cells or incubated with the stem cell-derived conditioned media on Matrigel. Following HUVEC-stem cell coculture, CD31-positive ECs were flow sorted and subjected to western blotting to analyze potential changes in the expression of the pro-angiogenic signaling molecules. Elongation and co-alignment of the stem cells were seen along the EC tubes in the EC-stem cell cocultures on Matrigel, with cell-to-cell dye communication in the EC-rBMSC cocultures. Moreover, rBMSCs and rADSCs significantly improved endothelial tubulogenesis in both juxtacrine and paracrine manners. These two latter stem cells dynamically up-regulated VEGF, Ang-2, VREGR-2, and Tie-2 but down-regulated Tie2-pho and the Tie2-pho/Tie-2 ratio in HUVECs. Induction of pro-angiogenic signaling in ECs by marrow- and adipose-derived MSCs further indicates the significance of stem cell milieu in angiogenesis dynamics.

  20. The effects of axotomy on neurons and satellite glial cells in mouse trigeminal ganglion.

    PubMed

    Cherkas, Pavel S; Huang, Tian-Ying; Pannicke, Thomas; Tal, Michael; Reichenbach, Andreas; Hanani, Menachem

    2004-07-01

    Damage to peripheral nerves induces ectopic firing in sensory neurons, which can contribute to neuropathic pain. As most of the information on this topic is on dorsal root ganglia we decided to examine the influence of infra-orbital nerve section on cells of murine trigeminal ganglia. We characterized the electrophysiological properties of neurons with intracellular electrodes. Changes in the coupling of satellite glial cells (SGCs) were monitored by intracelluar injection of the fluorescent dye Lucifer yellow. Electrophysiology of SGCs was studied with the patch-clamp technique. Six to eight days after axotomy, the percentage of neurons that fire spontaneously increased from 1.6 to 12.8%, the membrane depolarized from -51.1 to -45.5 mV, the percentage of cells with spontaneous potential oscillations increased from 19 to 37%, the membrane input resistance decreased from 44.4 to 39.5 MOmega, and the threshold for firing an action potential decreased from 0.61 to 0.42 nA. These changes are consistent with increased neuronal excitability. SGCs were mutually coupled around a given neuron in 21% of the cases, and to SGCs around neighboring neurons in only 4.8% of the cases. After axotomy these values increased to 37.1 and 25.8%, respectively. After axotomy the membrane resistance of SGCs decreased from 101 MOmega in controls to 40 MOmega, possibly due to increased coupling among these cells. We conclude that axotomy affects both neurons and SGCs in the trigeminal ganglion. The increased neuronal excitability and ectopic firing may play a major role in neuropathic pain.

  1. Clonal Characterization of Rat Muscle Satellite Cells: Proliferation, Metabolism and Differentiation Define an Intrinsic Heterogeneity

    PubMed Central

    Rossi, Carlo A.; Pozzobon, Michela; Ditadi, Andrea; Archacka, Karolina; Gastaldello, Annalisa; Sanna, Marta; Franzin, Chiara; Malerba, Alberto; Milan, Gabriella; Cananzi, Mara; Schiaffino, Stefano; Campanella, Michelangelo; Vettor, Roberto; De Coppi, Paolo

    2010-01-01

    Satellite cells (SCs) represent a distinct lineage of myogenic progenitors responsible for the postnatal growth, repair and maintenance of skeletal muscle. Distinguished on the basis of their unique position in mature skeletal muscle, SCs were considered unipotent stem cells with the ability of generating a unique specialized phenotype. Subsequently, it was demonstrated in mice that opposite differentiation towards osteogenic and adipogenic pathways was also possible. Even though the pool of SCs is accepted as the major, and possibly the only, source of myonuclei in postnatal muscle, it is likely that SCs are not all multipotent stem cells and evidences for diversities within the myogenic compartment have been described both in vitro and in vivo. Here, by isolating single fibers from rat flexor digitorum brevis (FDB) muscle we were able to identify and clonally characterize two main subpopulations of SCs: the low proliferative clones (LPC) present in major proportion (∼75%) and the high proliferative clones (HPC), present instead in minor amount (∼25%). LPC spontaneously generate myotubes whilst HPC differentiate into adipocytes even though they may skip the adipogenic program if co-cultured with LPC. LPC and HPC differ also for mitochondrial membrane potential (ΔΨm), ATP balance and Reactive Oxygen Species (ROS) generation underlying diversities in metabolism that precede differentiation. Notably, SCs heterogeneity is retained in vivo. SCs may therefore be comprised of two distinct, though not irreversibly committed, populations of cells distinguishable for prominent differences in basal biological features such as proliferation, metabolism and differentiation. By these means, novel insights on SCs heterogeneity are provided and evidences for biological readouts potentially relevant for diagnostic purposes described. PMID:20049087

  2. The solar maximum satellite capture cell: Impact features and orbital debris and micrometeoritic projectile materials

    NASA Technical Reports Server (NTRS)

    Mckay, D. S.; Rietmeijer, F. J. M.; Schramm, L. S.; Barrett, R. A.; Zook, H. A.; Blanford, G. E.

    1986-01-01

    The physical properties of impact features observed in the Solar Max main electronics box (MEB) thermal blanket generally suggest an origin by hypervelocity impact. The chemistry of micrometeorite material suggests that a wide variety of projectile materials have survived impact with retention of varying degrees of pristinity. Impact features that contain only spacecraft paint particles are on average smaller than impact features caused by micrometeorite impacts. In case both types of materials co-occur, it is belevied that the impact feature, generally a penetration hole, was caused by a micrometeorite projectile. The typically smaller paint particles were able to penetrate though the hole in the first layer and deposit in the spray pattern on the second layer. It is suggested that paint particles have arrived with a wide range of velocities relative to the Solar Max satellite. Orbiting paint particles are an important fraction of materials in the near-Earth environment. In general, the data from the Solar Max studies are a good calibration for the design of capture cells to be flown in space and on board Space Station. The data also suggest that development of multiple layer capture cells in which the projectile may retain a large degree of pristinity is a feasible goal.

  3. Peripheral inflammation augments gap junction-mediated coupling among satellite glial cells in mouse sympathetic ganglia.

    PubMed

    Hanani, Menachem; Caspi, Anna; Belzer, Vitali

    2010-02-01

    Intercellular coupling by gap junctions is one of the main features of glial cells, but very little is known about this aspect of satellite glial cells (SGCs) in sympathetic ganglia. We used the dye coupling method to address this question in both a prevertebral ganglion (superior mesenteric) and a paravertebral ganglion (superior cervical) of mice. We found that in control ganglia, the incidence of dye coupling among SGCs that form the envelope around a given neuron was 10-20%, and coupling between SGCs around different envelopes was rare (1.5-3%). The dye injections also provided novel information on the structure of SGCs. Following peripheral inflammation, both types of coupling were increased, but most striking was the augmentation of coupling between SGCs forming envelopes around different neurons, which rose by 8-14.6-fold. This effect appeared to be non-systemic, and was blocked by the gap junction blocker carbenoxolone. These changes in SGCs may affect signal transmission and processing in sympathetic ganglia.

  4. Regulation of mouse satellite DNA replication time.

    PubMed

    Selig, S; Ariel, M; Goitein, R; Marcus, M; Cedar, H

    1988-02-01

    The satellite DNA sequences located near the centromeric regions of mouse chromosomes replicate very late in S in both fibroblast and lymphocyte cells and are heavily methylated at CpG residues. F9 teratocarcinoma cells, on the other hand, contain satellite sequences which are undermethylated and replicate much earlier in S. DNA methylation probably plays some role in the control of satellite replication time since 5-azacytidine treatment of RAG fibroblasts causes a dramatic temporal shift of replication to mid S. In contrast to similar changes accompanying the inactivation of the X-chromosome, early replication of satellite DNA is not associated with an increase in local chromosomal DNase I sensitivity. Fusion of F9 with mouse lymphocytes caused a dramatic early shift in the timing of the normally late replicating lymphocyte satellite heterochromatin, suggesting that trans-activating factors may be responsible for the regulation of replication timing.

  5. Active machine learning for rapid landslide inventory mapping with VHR satellite images (Invited)

    NASA Astrophysics Data System (ADS)

    Stumpf, A.; Lachiche, N.; Malet, J.; Kerle, N.; Puissant, A.

    2013-12-01

    VHR satellite images have become a primary source for landslide inventory mapping after major triggering events such as earthquakes and heavy rainfalls. Visual image interpretation is still the prevailing standard method for operational purposes but is time-consuming and not well suited to fully exploit the increasingly better supply of remote sensing data. Recent studies have addressed the development of more automated image analysis workflows for landslide inventory mapping. In particular object-oriented approaches that account for spatial and textural image information have been demonstrated to be more adequate than pixel-based classification but manually elaborated rule-based classifiers are difficult to adapt under changing scene characteristics. Machine learning algorithm allow learning classification rules for complex image patterns from labelled examples and can be adapted straightforwardly with available training data. In order to reduce the amount of costly training data active learning (AL) has evolved as a key concept to guide the sampling for many applications. The underlying idea of AL is to initialize a machine learning model with a small training set, and to subsequently exploit the model state and data structure to iteratively select the most valuable samples that should be labelled by the user. With relatively few queries and labelled samples, an AL strategy yields higher accuracies than an equivalent classifier trained with many randomly selected samples. This study addressed the development of an AL method for landslide mapping from VHR remote sensing images with special consideration of the spatial distribution of the samples. Our approach [1] is based on the Random Forest algorithm and considers the classifier uncertainty as well as the variance of potential sampling regions to guide the user towards the most valuable sampling areas. The algorithm explicitly searches for compact regions and thereby avoids a spatially disperse sampling pattern

  6. A Micro Fluorescent Activated Cell Sorter for Astrobiology Applications

    NASA Technical Reports Server (NTRS)

    Platt, Donald W.; Hoover, Richard B.

    2009-01-01

    A micro-scale Fluorescent Activated Cell Sorter (microFACS) for astrobiology applications is under development. This device is designed to have a footprint of 7 cm x 7 cm x 4 cm and allow live-dead counts and sorting of cells that have fluorescent characteristics from staining. The FACS system takes advantage of microfluidics to create a cell sorter that can fit in the palm of the hand. A micron-scale channel allows cells to pass by a blue diode which causes emission of marker-expressed cells which are detected by a filtered photodetector. A small microcontroller then counts cells and operates high speed valves to select which chamber the cell is collected in (a collection chamber or a waste chamber). Cells with the expressed characteristic will be collected in the collection chamber. This system has been built and is currently being tested. We are also designing a system with integrated MEMS-based pumps and valves for a small and compact unit to fly on small satellite-based biology experiments.

  7. Community effect triggers terminal differentiation of myogenic cells derived from muscle satellite cells by quenching Smad signaling

    SciTech Connect

    Yanagisawa, Michiko; Mukai, Atsushi; Shiomi, Kosuke; Song, Si-Yong; Hashimoto, Naohiro

    2011-01-15

    A high concentration of bone morphogenetic proteins (BMPs) stimulates myogenic progenitor cells to undergo heterotopic osteogenic differentiation. However, the physiological role of the Smad signaling pathway during terminal muscle differentiation has not been resolved. We report here that Smad1/5/8 was phosphorylated and activated in undifferentiated growing mouse myogenic progenitor Ric10 cells without exposure to any exogenous BMPs. The amount of phosphorylated Smad1/5/8 was severely reduced during precocious myogenic differentiation under the high cell density culture condition even in growth medium supplemented with a high concentration of serum. Inhibition of the Smad signaling pathway by dorsomorphin, an inhibitor of Smad activation, or noggin, a specific antagonist of BMP, induced precocious terminal differentiation of myogenic progenitor cells in a cell density-dependent fashion even in growth medium. In addition, Smad1/5/8 was transiently activated in proliferating myogenic progenitor cells during muscle regeneration in rats. The present results indicate that the Smad signaling pathway is involved in a critical switch between growth and differentiation of myogenic progenitor cells both in vitro and in vivo. Furthermore, precocious cell density-dependent myogenic differentiation suggests that a community effect triggers the terminal muscle differentiation of myogenic cells by quenching the Smad signaling.

  8. Pattern of Pax7 expression during myogenesis in the posthatch chicken establishes a model for satellite cell differentiation and renewal.

    PubMed

    Halevy, Orna; Piestun, Yogev; Allouh, Mohammed Z; Rosser, Benjamin W C; Rinkevich, Yuval; Reshef, Ram; Rozenboim, Israel; Wleklinski-Lee, Monika; Yablonka-Reuveni, Zipora

    2004-11-01

    The paired-box transcription factor Pax7 plays a critical role in the specification of satellite cells in mouse skeletal muscle. In the present study, the position and number of Pax7-expressing cells found in muscles of growing and adult chickens confirm the presence of this protein in avian satellite cells. The expression pattern of Pax7 protein, along with the muscle regulatory proteins MyoD and myogenin, was additionally elucidated in myogenic cultures and in whole muscle from posthatch chickens. In cultures progressing from proliferation to differentiation, the expression of Pax7 in MyoD+ cells declined as the cells began expressing myogenin, suggesting Pax7 as an early marker for proliferating myoblasts. At all time points, some Pax7+ cells were negative for MyoD, resembling the reserve cell phenotype. Clonal analysis of muscle cell preparations demonstrated that single progenitors can give rise to both differentiating and reserve cells. In muscle tissues, Pax7 protein expression was the strongest by 1 day posthatch, declining on days 3 and 6 to a similar level. In contrast, myogenin expression peaked on day 3 and then dramatically declined. This finding was accompanied by a robust growth in fiber diameter between day 3 and 6. The distinctions in Pax7 and myogenin expression patterns, both in culture and in vivo, indicate that while some of the myoblasts differentiate and fuse into myofibers during early stages of posthatch growth, others retain their reserve cell capacity.

  9. Aged Muscle Demonstrates Fiber-Type Adaptations in Response to Mechanical Overload, in the Absence of Myofiber Hypertrophy, Independent of Satellite Cell Abundance.

    PubMed

    Lee, Jonah D; Fry, Christopher S; Mula, Jyothi; Kirby, Tyler J; Jackson, Janna R; Liu, Fujun; Yang, Lin; Dupont-Versteegden, Esther E; McCarthy, John J; Peterson, Charlotte A

    2016-04-01

    Although sarcopenia, age-associated loss of muscle mass and strength, is neither accelerated nor exacerbated by depletion of muscle stem cells, satellite cells, we hypothesized that adaptation in sarcopenic muscle would be compromised. To test this hypothesis, we depleted satellite cells with tamoxifen treatment of Pax7(CreER)-DTA mice at 4 months of age, and 20 months later subjected the plantaris muscle to 2 weeks of mechanical overload. We found myofiber hypertrophy was impaired in aged mice regardless of satellite cell content. Even in the absence of growth, vehicle-treated mice mounted a regenerative response, not apparent in tamoxifen-treated mice. Further, myonuclear accretion occurred in the absence of growth, which was prevented by satellite cell depletion, demonstrating that myonuclear addition is insufficient to drive myofiber hypertrophy. Satellite cell depletion increased extracellular matrix content of aged muscle that was exacerbated by overload, potentially limiting myofiber growth. These results support the idea that satellite cells regulate the muscle environment, and that their loss during aging may contribute to fibrosis, particularly during periods of remodeling. Overload induced a fiber-type composition improvement, independent of satellite cells, suggesting that aged muscle is very responsive to exercise-induced enhancement in oxidative capacity, even with an impaired hypertrophic response.

  10. Capturing the fingerprint of Etna volcano activity in gravity and satellite radar data

    PubMed Central

    Negro, Ciro Del; Currenti, Gilda; Solaro, Giuseppe; Greco, Filippo; Pepe, Antonio; Napoli, Rosalba; Pepe, Susi; Casu, Francesco; Sansosti, Eugenio

    2013-01-01

    Long-term and high temporal resolution gravity and deformation data move us toward a better understanding of the behavior of Mt Etna during the June 1995 – December 2011 period in which the volcano exhibited magma charging phases, flank eruptions and summit crater activity. Monthly repeated gravity measurements were coupled with deformation time series using the Differential Synthetic Aperture Radar Interferometry (DInSAR) technique on two sequences of interferograms from ERS/ENVISAT and COSMO-SkyMed satellites. Combining spatiotemporal gravity and DInSAR observations provides the signature of three underlying processes at Etna: (i) magma accumulation in intermediate storage zones, (ii) magmatic intrusions at shallow depth in the South Rift area, and (iii) the seaward sliding of the volcano's eastern flank. Here we demonstrate the strength of the complementary gravity and DInSAR analysis in discerning among different processes and, thus, in detecting deep magma uprising in months to years before the onset of a new Etna eruption. PMID:24169569

  11. Sentinel-1 Data System at the Alaska Satellite Facility Distributed Active Archive Center

    NASA Astrophysics Data System (ADS)

    Wolf, V. G.

    2014-12-01

    The Alaska Satellite Facility Distributed Active Archive Center (ASF DAAC) has a long history of supporting international collaborations between NASA and foreign flight agencies to promote access to Synthetic Aperture Radar (SAR) data for US science research. Based on the agreement between the US and the EC, data from the Sentinel missions will be distributed by NASA through archives that mirror those established by ESA. The ASF DAAC is the designated archive and distributor for Sentinel-1 data. The data will be copied from the ESA archive to a rolling archive at the NASA Goddard center, and then pushed to a landing area at the ASF DAAC. The system at ASF DAAC will take the files as they arrive and put them through an ingest process. Ingest will populate the database with the information required to enable search and download of the data through Vertex, the ASF DAAC user interface. Metadata will be pushed to the NASA Common Metadata Repository, enabling data discovery through clients that utilize the repository. Visual metadata will be pushed to the NASA GIBS system for visualization through clients linked to that system. Data files will be archived in the DataDirect Networks (DDN) device that is the primary storage device for the ASF DAAC. A backup copy of the data will be placed in a second DDN device that serves as the disaster recovery solution for the ASF DAAC.

  12. Satellite estimation of photosynthetically active radiation in Southeast Asia: Impacts of smoke and cloud cover

    NASA Astrophysics Data System (ADS)

    Kobayashi, Hideki; Matsunaga, Tsuneo; Hoyano, Akira; Aoki, Masatoshi; Komori, Daisuke; Boonyawat, Samakkee

    2004-02-01

    Since large-scale variations in photosynthetically active radiation (PAR) influence the terrestrial carbon sources and sinks through the plant photosynthesis variations, large-scale evaluation of PAR is required. In the present study a simple PAR estimation model was developed for Southeast Asia, where large-scale forest fires occurred during El Niño years. The model considered the smoke aerosol released by forest fires using satellite-based smoke detection methods. A comparison study with ground-based solar radiation data for Malaysia and Thailand indicated that the current model could estimate monthly PAR with 10% (root-mean-square) accuracy and would successfully trace the seasonal and year-to-year variations in PAR, including the forest fire periods. During the peak-smoke month in Indonesia, September 1997, the reduction of PAR by smoke reached 63-75% in the center of the Kalimantan and Sumatra Islands. From the analyses of the smoke and cloud cover impacts on PAR in 1997-1999, annual PAR variations were found to be mostly regulated by smoke variations on the Malay Peninsula, Sumatra, and Kalimantan Islands and cloud cover variations on the Indo-China Peninsula. Thus annual variations in PAR changed with location. These variations did not simply correlate with year-to-year variations in cloud cover associated with the El Niño and La Niña cycle, but exhibited more complicated spatial variations due to the existence of smoke in Southeast Asia.

  13. First satellite measurements of chemical changes in coincidence with sprite activity

    NASA Astrophysics Data System (ADS)

    Arnone, Enrico; São Sabbas, Fernanda; Kero, Antti; Soula, Serge; Carlotti, Massimo; Chanrion, Olivier; Dinelli, Bianca Maria; Papandrea, Enzo; Castelli, Elisa; Neubert, Torsten

    2010-05-01

    The last twenty years have seen the discovery of electric discharges in the Earth's atmosphere above thunderstorms, the so-called sprites and jets. It has been suggested that they impact the atmospheric chemistry and possibly affect the ozone layer through their repeated occurrence. Whereas theoretical studies and laboratory experiments suggest enhancement of such gasses as nitrogen oxides by up to hundreds of percent within sprites, a definitive detection of their chemical effects have to date been unsuccessful. In this paper, we report on the first measurements of atmospheric chemical perturbations recorded in coincidence with sprite activity. A striking event occurred on 25 August 2003 when the MIPAS spectrometer onboard the Envisat satellite recorded spectroscopic measurements soon after a sequence of 11 sprites observed above Corsica (France) by Eurosprite ground facilities (details of the convective system are discussed in a companion paper by São Sabbas et al.). The measurements show an enhancement of ambient nitrous oxide by 80% at 52 km altitude in the region above the parent thunderstorm. The recorded chemical changes imply sprites can exert significant modification of the atmospheric chemistry at a regional scale, confirming model and laboratory predictions of sprite-chemistry, and requiring a new estimate of their global impact. The results of the analysis and their implications are discussed.

  14. Muscle Fiber Characteristics, Satellite Cells and Soccer Performance in Young Athletes

    PubMed Central

    Metaxas, Thomas I.; Mandroukas, Athanasios; Vamvakoudis, Efstratios; Kotoglou, Kostas; Ekblom, Björn; Mandroukas, Konstantinos

    2014-01-01

    This study is aimed to examine the muscle fiber type, composition and satellite cells in young male soccer players and to correlate them to cardiorespiratory indices and muscle strength. The participants formed three Groups: Group A (n = 13), 11.2 ± 0.4yrs, Group B (n=10), 13.1 ± 0.5yrs and Group C (n = 9), 15.2 ± 0.6yrs. Muscle biopsies were obtained from the vastus lateralis. Peak torque values of the quadriceps and hamstrings were recorded and VO2max was measured on the treadmill. Group C had lower type I percentage distribution compared to A by 21.3% (p < 0.01), while the type IIA relative percentage was higher by 18.1% and 18.4% than in Groups A and B (p < 0.05). Groups B and C had higher cross-sectional area (CSA) values in all fiber types than in Group A (0.05 < p < 0.001). The number of satellite cells did not differ between the groups. Groups B and C had higher peak torque at all angular velocities and absolute VO2max in terms of ml·min-1 than Group A (0.05 < p < 0.001). It is concluded that the increased percentage of type IIA muscle fibers noticed in Group C in comparison to the Groups A and B should be mainly attributed to the different workload exercise and training programs. The alteration of myosin heavy chain (MHC) isoforms composition even in children is an important mechanism for skeletal muscle characteristics. Finally, CSA, isokinetic muscle strength and VO2max values seems to be expressed according to age. Key Points Fifteen years old soccer players have higher IIA percentage distribution than the younger players by approximately 18%. The age and the training status play a crucial role in muscle fibers co-expression. Specific training in young athletes seems to alter significantly the muscular metabolic profile. PMID:25177173

  15. Dye coupling among satellite glial cells in mammalian dorsal root ganglia.

    PubMed

    Huang, Tian-Ying; Cherkas, Pavel S; Rosenthal, David W; Hanani, Menachem

    2005-03-02

    Dorsal root ganglia (DRG) are key elements in sensory signaling under physiological and pathological conditions. Little is known about electrical coupling among cells in these ganglia. In this study, we injected the fluorescent dye Lucifer yellow (LY) into single cells to examine dye coupling in DRG. We found no dye coupling between neurons or between neurons and their attendant satellite glial cells (SGCs). In mouse DRG, we observed that in 26.2% of the cases SGCs that surround a given neuron were dye coupled. In only 3.2% of the cases SGCs that make envelopes around different neurons were coupled. The data from mouse ganglia were very similar to those from rat and guinea pig DRG. The results obtained by injection of the tracer biocytin were very similar to those observed with LY. The coupling incidence within the envelopes increased 3.1-fold by high extracellular pH (8.0), but coupling between envelopes was not affected. Acidic pH (6.8) reduced the coupling. High extracellular K+ (9.4 mM) increased the coupling 2.4-fold and 4.7-fold within and between envelopes, respectively. Low extracellular Ca2+ (0.5, 1.0 mM) partly reversed the effect of high K+ on coupling. The results showed that SGCs in mammalian sensory ganglia are connected by gap junctions. This coupling is very sensitive to changes in pH, and can therefore be modulated under various physiological and pathological conditions. The dependence of the coupling on extracellular K+ and Ca2+ suggests that the permeability of gap junctions can be altered by physiological and pharmacological stimuli.

  16. Comparison of ground and satellite based measurements of the fraction of photosynthetically active radiation intercepted by tall-grass prairie

    NASA Technical Reports Server (NTRS)

    Demetriades-Shah, T. H.; Kanemasu, E. T.; Flitcroft, I.; Su, H.

    1991-01-01

    The fraction, of photosynthetically active radiation intercepted by vegetation, F(sub ipar) is an important parameter for modeling the interactions between the land-surface and atmosphere and for estimating vegetation biomass productivity. This study was; therefore, an integral part of FIFE. The specific purpose of this experiment was to find out how well definitive measurements of F(sub ipar) on the ground relate to near-ground and satellite based spectral reflectance measurements. Concurrent measurements of F(sub ipar) and ground, helicopter, and satellite based reflectance measurements were taken at thirteen tall-grass prairie sites within the FIFE experimental area. The sites were subjected to various combinations of burning and grazing managements. The ground and helicopter based reflectance measurements were taken on the same day or few days from the time of the overpass of LANDSAT and SPOT satellites. Ground-based reflectance measurements and sun photometer readings taken at the times of the satellite overpasses were used to correct for atmospheric attenuation. Hand-held radiometer spectral indices were strongly correlated with helicopter and satellite based values (r=0.94 for helicopter, 0.93 for LANDSAT Thematic Mapper, and 0.86 for SPOT). However, the ground, helicopter, and satellite based normalized difference spectral vegetation indices showed low sensitivity to changes in F(sub ipar). Reflectance measurements were only moderately well correlated with measurements of F(sub ipar) (r=0.82 for hand-held radiometer, 0.84 for helicopter measurements, and 0.75 for the LANDSAT Thematic Mapper and SPOT). Improved spectral indices which can compensate for site differences are needed in order to monitor F(sub ipar) more reliably.

  17. Comparison of ground and satellite based measurements of the fraction of photosynthetically active radiation intercepted by tall-grass prairie

    NASA Technical Reports Server (NTRS)

    Demetriades-Shah, T. H.; Kanemasu, E. T.; Flitcroft, I. D.; Su, H.

    1992-01-01

    The fraction of photosynthetically active radiation intercepted by vegetation, F(sub ipar) is an important parameter for modeling the interactions between the land-surface and atmosphere and for estimating vegetation biomass productivity. This study was, therefore, an integral part of FIFE. The specific purpose of this experiment was to find out how well definitive measurements of F(sub ipar) on the ground relate to near-ground and satellite based spectral reflectance measurements. Concurrent measurements of F(sub ipar) and ground, helicopter, and satellite based reflectance measurements were taken at thirteen tall-grass prairie sites within the FIFE experimental area. The sites were subjected to various combinations of burning and grazing managements. The ground and helicopter based reflectance measurements were taken on the same day or few days from the time of the overpass of LANDSAT and SPOT satellites. Ground-based reflectance measurements and sun photometer readings taken at the times of the satellite overpasses were used to correct for atmospheric attenuation. Hand-held radiometer spectral indices were strongly correlated with helicopter and satellite based values (r = 0.94 for helicopter, 0.93 for LANDSAT Thematic Mapper, and 0.86 for SPOT). However, the ground, helicopter, and satellite based normalized difference spectral vegetation indices showed low sensitivity to changes in F(sub ipar). Reflectance measurements were only moderately well correlated with measurements of F(sub ipar) (r = 0.82 for hand-held radiometer, 0.84 for helicopter measurements, and 0.75 for the LANDSAT Thematic Mapper and SPOT). Improved spectral indices which can compensate for site differences are needed in order to monitor F(sub ipar) more reliably.

  18. Mast cells enhance T cell activation: Importance of mast cell-derived TNF

    NASA Astrophysics Data System (ADS)

    Nakae, Susumu; Suto, Hajime; Kakurai, Maki; Sedgwick, Jonathon D.; Tsai, Mindy; Galli, Stephen J.

    2005-05-01

    Mast cells are not only important effector cells in immediate hypersensitivity reactions and immune responses to pathogens but also can contribute to T cell-mediated disorders. However, the mechanisms by which mast cells might influence T cells in such settings are not fully understood. We find that mast cells can enhance proliferation and cytokine production in multiple T cell subsets. Mast cell-dependent enhancement of T cell activation can be promoted by FcRI-dependent mast cell activation, TNF production by both mast cells and T cells, and mast cell-T cell contact. However, at high concentrations of cells, mast cells can promote T cell activation independent of IgE or TNF. Finally, mast cells also can promote T cell activation by means of soluble factors. These findings identify multiple mechanisms by which mast cells can influence T cell proliferation and cytokine production. allergy | asthma | autoimmunity | cytokines | immune response

  19. The Spindle Assembly Checkpoint Safeguards Genomic Integrity of Skeletal Muscle Satellite Cells.

    PubMed

    Kollu, Swapna; Abou-Khalil, Rana; Shen, Carl; Brack, Andrew S

    2015-06-09

    To ensure accurate genomic segregation, cells evolved the spindle assembly checkpoint (SAC), whose role in adult stem cells remains unknown. Inducible perturbation of a SAC kinase, Mps1, and its downstream effector, Mad2, in skeletal muscle stem cells shows the SAC to be critical for normal muscle growth, repair, and self-renewal of the stem cell pool. SAC-deficient muscle stem cells arrest in G1 phase of the cell cycle with elevated aneuploidy, resisting differentiation even under inductive conditions. p21(CIP1) is responsible for these SAC-deficient phenotypes. Despite aneuploidy's correlation with aging, we find that aged proliferating muscle stem cells display robust SAC activity without elevated aneuploidy. Thus, muscle stem cells have a two-step mechanism to safeguard their genomic integrity. The SAC prevents chromosome missegregation and, if it fails, p21(CIP1)-dependent G1 arrest limits cellular propagation and tissue integration. These mechanisms ensure that muscle stem cells with compromised genomes do not contribute to tissue homeostasis.

  20. Fiber Type-Specific Satellite Cell Content in Cyclists Following Heavy Training with Carbohydrate and Carbohydrate-Protein Supplementation

    PubMed Central

    McKenzie, Alec I.; D'Lugos, Andrew C.; Saunders, Michael J.; Gworek, Keith D.; Luden, Nicholas D.

    2016-01-01

    The central purpose of this study was to evaluate the fiber type-specific satellite cell and myonuclear responses of endurance-trained cyclists to a block of intensified training, when supplementing with carbohydrate (CHO) vs. carbohydrate-protein (PRO). In a crossover design, endurance-trained cyclists (n = 8) performed two consecutive training periods, once supplementing with CHO (de facto “control” condition) and the other with PRO. Each training period consisted of 10 days of intensified cycle training (ICT–120% increase in average training duration) followed by 10 days of recovery (RVT–reduced volume training; 33% volume reduction vs. normal training). Skeletal muscle biopsies were obtained from the vastus lateralis before and after ICT and again following RVT. Immunofluorescent microscopy was used to quantify SCs (Pax7+), myonuclei (DAPI+), and myosin heavy chain I (MyHC I). Data are expressed as percent change ± 90% confidence limits. The 10-day block of ICTCHO increased MyHC I SC content (35 ± 28%) and myonuclear density (16 ± 6%), which remained elevated following RVTCHO (SC = 69 ± 50% vs. PRE; Nuclei = 17 ± 15% vs. PRE). MyHC II SC and myonuclei were not different following ICTCHO, but were higher following RVTCHO (SC = +33 ± 31% vs. PRE; Nuclei = 15 ± 14% vs. PRE), indicating a delayed response compared to MyHC I fibers. The MyHC I SC pool increased following ICTPRO (37 ± 37%), but without a concomitant increase in myonuclei. There were no changes in MyHC II SC or myonuclei following ICTPRO. Collectively, these trained endurance cyclists possessed a relatively large pool of SCs that facilitated rapid (MyHC I) and delayed (MyHC II) satellite cell proliferation and myonuclear accretion under carbohydrate conditions. The current findings strengthen the growing body of evidence demonstrating alterations in satellite cell number in the absence of hypertrophy. Satellite cell pool expansion is typically viewed as an advantageous response to

  1. Fiber Type-Specific Satellite Cell Content in Cyclists Following Heavy Training with Carbohydrate and Carbohydrate-Protein Supplementation.

    PubMed

    McKenzie, Alec I; D'Lugos, Andrew C; Saunders, Michael J; Gworek, Keith D; Luden, Nicholas D

    2016-01-01

    The central purpose of this study was to evaluate the fiber type-specific satellite cell and myonuclear responses of endurance-trained cyclists to a block of intensified training, when supplementing with carbohydrate (CHO) vs. carbohydrate-protein (PRO). In a crossover design, endurance-trained cyclists (n = 8) performed two consecutive training periods, once supplementing with CHO (de facto "control" condition) and the other with PRO. Each training period consisted of 10 days of intensified cycle training (ICT-120% increase in average training duration) followed by 10 days of recovery (RVT-reduced volume training; 33% volume reduction vs. normal training). Skeletal muscle biopsies were obtained from the vastus lateralis before and after ICT and again following RVT. Immunofluorescent microscopy was used to quantify SCs (Pax7+), myonuclei (DAPI+), and myosin heavy chain I (MyHC I). Data are expressed as percent change ± 90% confidence limits. The 10-day block of ICTCHO increased MyHC I SC content (35 ± 28%) and myonuclear density (16 ± 6%), which remained elevated following RVTCHO (SC = 69 ± 50% vs. PRE; Nuclei = 17 ± 15% vs. PRE). MyHC II SC and myonuclei were not different following ICTCHO, but were higher following RVTCHO (SC = +33 ± 31% vs. PRE; Nuclei = 15 ± 14% vs. PRE), indicating a delayed response compared to MyHC I fibers. The MyHC I SC pool increased following ICTPRO (37 ± 37%), but without a concomitant increase in myonuclei. There were no changes in MyHC II SC or myonuclei following ICTPRO. Collectively, these trained endurance cyclists possessed a relatively large pool of SCs that facilitated rapid (MyHC I) and delayed (MyHC II) satellite cell proliferation and myonuclear accretion under carbohydrate conditions. The current findings strengthen the growing body of evidence demonstrating alterations in satellite cell number in the absence of hypertrophy. Satellite cell pool expansion is typically viewed as an advantageous response to exercise

  2. Development of a satellite flywheel family operating on one active axis magnetic bearings

    NASA Technical Reports Server (NTRS)

    Poubeau, P. C.

    1977-01-01

    Since the samarium-cobalt magnets were available at industrial level, new possibilities appeared in the area of magnetic bearings with the radial passive centering and axial control of the rotor position. Magnetic bearings of this type on which a wide effort was made towards the optimization for satellite flywheel applications are described. Also, the momentum and reaction wheels were considered. This work was extended to the kinetic storage of energy for satellites.

  3. Synchronous Tests of Laser Active ARTEMIS Satellite at Different Ground Stations

    NASA Astrophysics Data System (ADS)

    Kozyryev, Yevgen; Sybiryakova, Yevgeniya; Shulga, Alexander; Kuzkov, Volodymyr; Kuzkov, Sergii; Lopachenko, Vladimir; Kozhukhov, Alexander; Rikhal'sky, Vladimir; Caramia, Vincenzo

    2014-05-01

    In July 2001, the geostationary satellite ARTEMIS with laser communication terminal OPALE on board was launched. Successful laser communication sessions were performed between ARTEMIS and low Earth orbiting (LEO) satellite SPOT-4. Regular laser communication experiments between the Optical Ground Station (OGS) of ESA and ARTEMIS were also performed. The laser communication sessions were successfully established between LEO satellite KIRARI and ARTEMIS. A laser communication link between LEO satellites with the data rate of 5.625 Gbps (5100 km distance) was established by the TESAT Spacecom in 2008. First laser communication experiments between the LADEE spacecraft at the lunar orbit and Earth OGS with a rate of 622 Mbps were realized in October 2013. The amount of information sent from telecommunication satellites located at the geostationary orbit is constantly increasing. There is a certain demand in high speed laser link data transmission between ground stations and satellites. For some LEO satellites, the direct transmission of information to a ground station is required. To reduce the influence of atmosphere, some of ground stations located in different climatic regions are needed. The Main Astronomical Observatory of Ukraine (MAO) have developed a compact laser communication system named LACES (Laser Atmospheric and Communicational Experiments with Satellites) using the Cassegrain focus of its 0.7 m telescope. The laser link between the LACES terminal of MAO and the OPALE terminal of ARTEMIS was established. During the pointing, OPALE terminal performs the beacon laser scanning of the territory where a MAO ground station is located. Several experimental observations of OPALE beacon laser scanning by ground stations located in different regions of Ukraine took place in 2012-2013 years. During the sessions, laser beacon peaks from OPALE were detected by the stations in Kyiv, Mykolaiv (500 km from Kyiv), Yevpatoriya (800 km from Kyiv), Odesa, and other stations

  4. Nucleosome arrangement in alpha-<