scholarly journals SARCOMERE SIZE IN DEVELOPING MUSCLES OF A TARSONEMID MITE

1961 ◽  
Vol 11 (1) ◽  
pp. 147-156 ◽  
Author(s):  
John Aronson
Keyword(s):  
Electron Microscopy ◽  
Muscle Fiber ◽  
Muscle Development ◽  
Muscle Fibers ◽  
Polarization Microscopy ◽  
Rate Of Increase ◽  
Constant Rate

The embryo of a tarsonemid mite was found to be suitable for in vivo observations of muscle development by polarization microscopy. The four dorsal muscles of the metapodosoma each contain three sarcomeres, the anterior two of which can be seen clearly. These sarcomeres can be identified and followed during much of their development. Sarcomeres are about 2.5 micra long when first detected and increase in length until they are about 10 micra long. The change in length is associated with a slow, approximately constant rate of increase in the length of the A region, and an initially slow then much more rapid increase in the length of the I band. Preceding the period when the I band elongates rapidly there is an increase in the diameter of the muscle fibers and an increase in the retardation of the A band. A, I, Z, and H bands are visible during most of these changes. The change in A band length has been interpreted in terms of the growth of the A filaments which have been observed by electron microscopy in muscles of other animals. It is suggested that the exceptionally long sarcomeres in this mite result from the early fixing of the number of sarcomeres in a given muscle fiber.

Formation of highly organized skeletal muscle fibers in vitro. Comparison with muscle development in vivo

1992 ◽  
Vol 102 (3) ◽  
pp. 643-652 ◽  
Author(s):  
S. Swasdison ◽  
R. Mayne
Keyword(s):  
Skeletal Muscle ◽  
Extracellular Matrix ◽  
Muscle Fiber ◽  
Muscle Development ◽  
Muscle Fibers ◽  
Myotendinous Junction ◽  
Type Iv

Two methods were developed in which long-term cultures of quail skeletal muscle were established so that all of the muscle fibers develop in a highly oriented manner. The muscle fibers became spontaneously and vigorously contractile and established strong connections with the extracellular matrix at their ends that closely duplicate the structure of the myotendinous junction. A continuous basal lamina was formed around each muscle fiber that contained type IV collagen, laminin and heparan sulfate proteoglycan. With one of the methods, an extensive extracellular matrix developed around each muscle fiber that was highly organized with the formation of a distinctive epimysium, perimysium and endomysium. Analysis of the cultures by both methods for different isoforms of myosin showed expression of an adult form of myosin by some of the muscle cells. The results therefore demonstrate that muscle development in the present culture systems proceeds extensively for several weeks. It will now be possible to investigate directly the structure of the connections between muscle fibers and the extracellular matrix.

Overlapping functions of the myogenic bHLH genes MRF4 and MyoD revealed in double mutant mice

Development ◽  
1998 ◽  
Vol 125 (13) ◽  
pp. 2349-2358 ◽  
Author(s):  
A. Rawls ◽  
M.R. Valdez ◽  
W. Zhang ◽  
J. Richardson ◽  
W.H. Klein ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Double Mutant ◽  
Muscle Development ◽  
Expression Patterns ◽  
Muscle Fibers ◽  
Mutant Mice ◽  
Myoblast Differentiation ◽  
Bhlh Genes ◽  
Bhlh Factors

The myogenic basic helix-loop-helix (bHLH) genes - MyoD, Myf5, myogenin and MRF4 - exhibit distinct, but overlapping expression patterns during development of the skeletal muscle lineage and loss-of-function mutations in these genes result in different effects on muscle development. MyoD and Myf5 have been shown to act early in the myogenic lineage to establish myoblast identity, whereas myogenin acts later to control myoblast differentiation. In mice lacking myogenin, there is a severe deficiency of skeletal muscle, but some residual muscle fibers are present in mutant mice at birth. Mice lacking MRF4 are viable and have skeletal muscle, but they upregulate myogenin expression, which could potentially compensate for the absence of MRF4. Previous studies in which Myf5 and MRF4 null mutations were combined suggested that these genes do not share overlapping myogenic functions in vivo. To determine whether the functions of MRF4 might overlap with those of myogenin or MyoD, we generated double mutant mice lacking MRF4 and either myogenin or MyoD. MRF4/myogenin double mutant mice contained a comparable number of residual muscle fibers to mice lacking myogenin alone and myoblasts from those double mutant mice formed differentiated multinucleated myotubes in vitro as efficiently as wild-type myoblasts, indicating that neither myogenin nor MRF4 is absolutely essential for myoblast differentiation. Whereas mice lacking either MRF4 or MyoD were viable and did not show defects in muscle development, MRF4/MyoD double mutants displayed a severe muscle deficiency similar to that in myogenin mutants. Myogenin was expressed in MRF4/MyoD double mutants, indicating that myogenin is insufficient to support normal myogenesis in vivo. These results reveal unanticipated compensatory roles for MRF4 and MyoD in the muscle differentiation pathway and suggest that a threshold level of myogenic bHLH factors is required to activate muscle structural genes, with this level normally being achieved by combinations of multiple myogenic bHLH factors.

scholarly journals Reduced force of diaphragm muscle fibers in patients with chronic thromboembolic pulmonary hypertension

2016 ◽  
Vol 311 (1) ◽  
pp. L20-L28 ◽  
Author(s):  
Emmy Manders ◽  
Peter I. Bonta ◽  
Jaap J. Kloek ◽  
Petr Symersky ◽  
Harm-Jan Bogaard ◽  
...  
Keyword(s):  
Pulmonary Hypertension ◽  
Muscle Fiber ◽  
Ex Vivo ◽  
Muscle Fibers ◽  
Chronic Thromboembolic Pulmonary Hypertension ◽  
Inspiratory Muscle ◽  
Force Generation ◽  
Diaphragm Muscle ◽  
Fast Twitch

Patients with pulmonary hypertension (PH) suffer from inspiratory muscle weakness. However, the pathophysiology of inspiratory muscle dysfunction in PH is unknown. We hypothesized that weakness of the diaphragm, the main inspiratory muscle, is an important contributor to inspiratory muscle dysfunction in PH patients. Our objective was to combine ex vivo diaphragm muscle fiber contractility measurements with measures of in vivo inspiratory muscle function in chronic thromboembolic pulmonary hypertension (CTEPH) patients. To assess diaphragm muscle contractility, function was studied in vivo by maximum inspiratory pressure (MIP) and ex vivo in diaphragm biopsies of the same CTEPH patients ( N = 13) obtained during pulmonary endarterectomy. Patients undergoing elective lung surgery served as controls ( N = 15). Muscle fiber cross-sectional area (CSA) was determined in cryosections and contractility in permeabilized muscle fibers. Diaphragm muscle fiber CSA was not significantly different between control and CTEPH patients in both slow-twitch and fast-twitch fibers. Maximal force-generating capacity was significantly lower in slow-twitch muscle fibers of CTEPH patients, whereas no difference was observed in fast-twitch muscle fibers. The maximal force of diaphragm muscle fibers correlated significantly with MIP. The calcium sensitivity of force generation was significantly reduced in fast-twitch muscle fibers of CTEPH patients, resulting in a ∼40% reduction of submaximal force generation. The fast skeletal troponin activator CK-2066260 (5 μM) restored submaximal force generation to levels exceeding those observed in control subjects. In conclusion, diaphragm muscle fiber contractility is hampered in CTEPH patients and contributes to the reduced function of the inspiratory muscles in CTEPH patients.

Patterning of fast and slow fibers within embryonic muscles is established independently of signals from the surrounding mesenchyme

Development ◽  
2001 ◽  
Vol 128 (13) ◽  
pp. 2537-2544 ◽  
Author(s):  
William Nikovits ◽  
Gordon M. Cann ◽  
Ruijin Huang ◽  
Bodo Christ ◽  
Frank E. Stockdale
Keyword(s):  
Muscle Fiber ◽  
Fiber Type ◽  
Muscle Fibers ◽  
Fiber Formation ◽  
Lateral Plate ◽  
Reciprocal Transplantation ◽  
Muscle Formation ◽  
Type Pattern ◽  
Mesenchymal Stroma

During embryonic development, and before functional innervation, a highly stereotypic pattern of slow- and fast-contracting primary muscle fibers is established within individual muscles of the limbs, from distinct populations of myoblasts. A difference between the fiber-type pattern found within chicken and quail pectoral muscles was exploited to investigate the contributions of somite-derived myogenic precursors and lateral plate-derived mesenchymal stroma to the establishment of muscle fiber-type patterns. Chimeric chicken/quail embryos were constructed by reciprocal transplantation of somites or lateral plate mesoderm at stages prior to muscle formation. Muscle fibers derived from quail myogenic precursors that had migrated into chicken stroma showed a quail pattern of mixed fast- and slow-contracting muscle fibers. Conversely, chicken myogenic precursors that had migrated into quail stroma showed a chicken pattern of nearly exclusive fast muscle fiber formation. These results demonstrate in vivo an intrinsic commitment to fiber-type on the part of the myoblast, independent of extrinsic signals it receives from the mesenchymal stroma in which it differentiates.

The Infection of Cells by Bullet-Shaped Viruses

1969 ◽  
Vol 27 ◽  
pp. 372-373
Author(s):  
Frederick A. Murphy ◽  
Alyne K. Harrison ◽  
Sylvia G. Whitfield
Keyword(s):  
Electron Microscopy ◽  
Physical Properties ◽  
Host Cell ◽  
Thin Section ◽  
Cultured Cells ◽  
Cell Infection ◽  
Thin Section Electron Microscopy ◽  
Section Electron ◽  
Section Electron Microscopy

The bullet-shaped viruses are currently classified together on the basis of similarities in virion morphology and physical properties. Biologically and ecologically the member viruses are extremely diverse. In searching for further bases for making comparisons of these agents, the nature of host cell infection, both in vivo and in cultured cells, has been explored by thin-section electron microscopy.

Development of the Foramen Secundum in the Chick as Observed by Scanning Electron Microscopy

1976 ◽  
Vol 34 ◽  
pp. 212-213
Author(s):  
M.J.C. Hendrix ◽  
D.E. Morse
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Procaine Hydrochloride ◽  
Cardiac Anomaly ◽  
Chick Embryos ◽  
Congenital Cardiac Anomaly ◽  
Septal Defects ◽  
Critical Point Drying ◽  
Scanning Electron

Atrial septal defects are considered the most common congenital cardiac anomaly occurring in humans. In studying the normal sequential development of the atrial septum, chick embryos of the White Leghorn strain were prepared for scanning electron microscopy and the results were then extrapolated to the human heart. One-hundred-eighty chick embryos from 2 to 21 days of age were removed from their shells and immersed in cold cacodylate-buffered aldehyde fixative . Twenty-four embryos through the first week post-hatching were perfused in vivo using cold cacodylate-buffered aldehyde fixative with procaine hydrochloride. The hearts were immediately dissected free and remained in the fixative a minimum of 2 hours. In most cases, the lateral atrial walls were removed during this period. The tissues were then dehydrated using a series of ascending grades of ethanol; final dehydration of the tissues was achieved via the critical point drying method followed by sputter-coating with goldpalladium.

Solving the mechanisms responsible for organelle behavior in vivo by same-cell correlative light and electron microscopy

1992 ◽  
Vol 50 (1) ◽  
pp. 14-15
Author(s):  
Conly L. Rieder
Keyword(s):  
Electron Microscopy ◽  
Quantitative Analysis ◽  
Light Microscopy ◽  
Living Cell ◽  
Light And Electron Microscopy ◽  
Time Behavior ◽  
Dynamic Interactions ◽  
Positive Identification ◽  
Cellular Components

The behavior of many cellular components, and their dynamic interactions, can be characterized in the living cell with considerable spatial and temporal resolution by video-enhanced light microscopy (video-LM). Indeed, under the appropriate conditions video-LM can be used to determine the real-time behavior of organelles ≤ 25-nm in diameter (e.g., individual microtubules—see). However, when pushed to its limit the structures and components observed within the cell by video-LM cannot be resolved nor necessarily even identified, only detected. Positive identification and a quantitative analysis often requires the corresponding electron microcopy (EM).

scholarly journals Frozen/thawed meat quality associated with muscle fiber characteristics of porcine longissimus thoracis et lumborum, psoas major, semimembranosus, and semitendinosus muscles

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Huilin Cheng ◽  
Sumin Song ◽  
Gap-Don Kim
Keyword(s):  
Meat Quality ◽  
Muscle Fiber ◽  
Shear Force ◽  
Muscle Fibers ◽  
Frozen Storage ◽  
Meat Color ◽  
Pork Meat ◽  
Psoas Major ◽  
The Relationship

AbstractTo evaluate the relationship between muscle fiber characteristics and the quality of frozen/thawed pork meat, four different muscles, M. longissimus thoracis et lumborum (LTL), M. psoas major (PM), M. semimembranosus (SM), and M. semitendinosus (ST), were analyzed from twenty carcasses. Meat color values (lightness, redness, yellowness, chroma, and hue) changed due to freezing/thawing in LTL, which showed larger IIAX, IIX, and IIXB fibers than found in SM (P < 0.05). SM and ST showed a significant decrease in purge loss and an increase in shear force caused by freezing/thawing (P < 0.05). Compared with LTL, SM contains more type IIXB muscle fibers and ST had larger muscle fibers I and IIA (P < 0.05). PM was the most stable of all muscles, since only its yellowness and chroma were affected by freezing/thawing (P < 0.05). These results suggest that pork muscle fiber characteristics of individual cuts must be considered to avoid quality deterioration during frozen storage.

scholarly journals Assessment of SnFe2O4 Nanoparticles for Potential Application in Theranostics: Synthesis, Characterization, In Vitro, and In Vivo Toxicity

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 825
Author(s):  
Saman Sargazi ◽  
Mohammad Reza Hajinezhad ◽  
Abbas Rahdar ◽  
Muhammad Nadeem Zafar ◽  
Aneesa Awan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
A549 Cells ◽  
In Vitro Cytotoxicity ◽  
Hek293 Cells ◽  
Hydrothermal Route ◽  
X Ray ◽  
Tin Chloride ◽  
Bet Analysis

In this research, tin ferrite (SnFe2O4) NPs were synthesized via hydrothermal route using ferric chloride and tin chloride as precursors and were then characterized in terms of morphology and structure using Fourier-transform infrared spectroscopy (FTIR), Ultraviolet–visible spectroscopy (UV-Vis), X-ray power diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), and Brunauer–Emmett–Teller (BET) method. The obtained UV-Vis spectra was used to measure band gap energy of as-prepared SnFe2O4 NPs. XRD confirmed the spinel structure of NPs, while SEM and TEM analyses disclosed the size of NPs in the range of 15–50 nm and revealed the spherical shape of NPs. Moreover, energy dispersive X-ray spectroscopy (EDS) and BET analysis was carried out to estimate elemental composition and specific surface area, respectively. In vitro cytotoxicity of the synthesized NPs were studied on normal (HUVEC, HEK293) and cancerous (A549) human cell lines. HUVEC cells were resistant to SnFe2O4 NPs; while a significant decrease in the viability of HEK293 cells was observed when treated with higher concentrations of SnFe2O4 NPs. Furthermore, SnFe2O4 NPs induced dramatic cytotoxicity against A549 cells. For in vivo study, rats received SnFe2O4 NPs at dosages of 0, 0.1, 1, and 10 mg/kg. The 10 mg/kg dose increased serum blood urea nitrogen and creatinine compared to the controls (P < 0.05). The pathology showed necrosis in the liver, heart, and lungs, and the greatest damages were related to the kidneys. Overall, the in vivo and in vitro experiments showed that SnFe2O4 NPs at high doses had toxic effects on lung, liver and kidney cells without inducing toxicity to HUVECs. Further studies are warranted to fully elucidate the side effects of SnFe2O4 NPs for their application in theranostics.

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