Ultrastructure of the caudal muscle cells in the larva of a polyclinid ascidian

1985 ◽  
Vol 63 (6) ◽  
pp. 1410-1419 ◽  
Author(s):  
Michael J. Cavey ◽  
Harvey D. Strecker
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Striated Muscle ◽  
Muscle Cells ◽  
The Other ◽  
The Cross

Two paraxial bands of somatic striated muscle occur in the tail of the larva of the compound ascidian Aplidium ?constellatum. The mononucleate muscle cells of each band align in longitudinal rows between the epidermis and the notochord. The cross-striated myofibrils, originating and terminating at intermediate junctions on the transverse cellular boundaries, are indiscrete. They follow a spiral course through the subcortical and medullary sarcoplasm, bypassing the nucleus and the other organelles and inclusions in the center of the cell. Cisternae of the sarcoplasmic reticulum envelop the myofibrils, forming compact fenestrated sheets that are continuous between the sarcomeres and locally undifferentiated with respect to the myofibrillar striations. Cisternae of the perifibrillar sarcoplasmic reticulum near each sarcomeric Z-line establish dyadic interior couplings with a network of tubular invaginations of the sarcolemma. The sarcolemmal tubules can originate from any surface, including the transverse cellular boundaries. Near the half I-bands of the terminal sarcomeres at the intermediate junctions, the perifibrillar cisternae frequently leave the fenestrated sheets and extend to the overlying sarcolemma, becoming the sub-sarcolemmal cisternae of dyadic peripheral couplings.

scholarly journals Characterization of the sarcoplasmic reticulum proteins in the thermogenic muscles of fish.

1994 ◽  
Vol 127 (5) ◽  
pp. 1275-1287 ◽  
Author(s):  
B A Block ◽  
J O'Brien ◽  
G Meissner
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Direct Evidence ◽  
Striated Muscle ◽  
High Capacity ◽  
Muscle Cells ◽  
Immunoblot Analysis ◽  
Fluorescent Labeling ◽  
T Tubules ◽  
The Brain

Marlins, sailfish, spearfishes, and swordfish have extraocular muscles that are modified into thermogenic organs beneath the brain. The modified muscle cells, called heater cells, lack organized myofibrils and are densely packed with sarcoplasmic reticulum (SR), transverse (T) tubules, and mitochondria. Thermogenesis in the modified extraocular muscle fibers is hypothesized to be associated with increased energy turnover due to Ca2+ cycling at the SR. In this study, the proteins associated with sequestering and releasing Ca2+ from the SR (ryanodine receptor, Ca2+ ATPase, calsequestrin) of striated muscle cells were characterized in the heater SR using immunoblot and immunofluorescent techniques. Immunoblot analysis with a monoclonal antibody that recognizes both isoforms of nonmammalian RYRs indicates that the fish heater cells express only the alpha RYR isoform. The calcium dependency of [3H]ryanodine binding to the RYR isoform expressed in heater indicates functional identity with the non-mammalian alpha RYR isoform. Fluorescent labeling demonstrates that the RYR is localized in an anastomosing network throughout the heater cell cytoplasm. Measurements of oxalate supported 45Ca2+ uptake, Ca2+ ATPase activity, and [32P]phosphoenzyme formation demonstrate that the SR contains a high capacity for Ca2+ uptake via an ATP dependent enzyme. Immunoblot analysis of calsequestrin revealed a significant amount of the Ca2+ binding protein in the heater cell SR. The present study provides the first direct evidence that the heater SR system contains the proteins necessary for Ca2+ release, re-uptake and sequestration, thus supporting the hypothesis that thermogenesis in the modified muscle cells is achieved via an ATP-dependent cycling of Ca2+ between the SR and cytosolic compartments.

scholarly journals THE DOUBLE ARRAY OF FILAMENTS IN CROSS-STRIATED MUSCLE

1957 ◽  
Vol 3 (5) ◽  
pp. 631-648 ◽  
Author(s):  
H. E. Huxley
Keyword(s):  
Striated Muscle ◽  
The Other ◽  
Thin Sections ◽  
Alternative Models ◽  
Double Array ◽  
The Cross ◽  
Cross Bridges

The conditions under which one might expect to see the secondary filaments (if they exist) in longitudinal sections of striated muscle, are discussed. It is shown that these conditions were not satisfied in previously published works for the sections were too thick. When suitably thin sections are examined, the secondary filaments can be seen perfectly easily. It is also possible to see clearly other details of the structure, notably the cross-bridges between primary and secondary filaments, and the tapering of the primary filaments at their ends. The arrangement of the filaments and the changes associated with contraction and with stretch are identical to those already deduced from previous observations and described in terms of the interdigitating filament model in previous papers. There are therefore excellent grounds for believing that this model is correct. The alternative models which have been proposed appear to be incompatible both with the present observations and with much of the other available evidence.

scholarly journals OBLIQUELY STRIATED MUSCLE

1968 ◽  
Vol 36 (1) ◽  
pp. 245-259 ◽  
Author(s):  
Jack Rosenbluth
Keyword(s):  
Electron Microscopy ◽  
Sarcoplasmic Reticulum ◽  
Connective Tissue ◽  
Striated Muscle ◽  
Muscle Cells ◽  
Body Muscle ◽  
Dense Bodies ◽  
Thick Filaments ◽  
Predominant Type ◽  
Physiological Differences

Body muscle cells of the bloodworm Glycera, a polychaete annelid, were studied by electron microscopy and compared with muscle cells of the more slowly acting nematode Ascaris, which have been described previously. Both muscles are obliquely striated. The predominant type of bloodworm fiber is characterized by a prominent transversely oriented sarcoplasmic reticulum with numerous dyads at the surface of each cell. Thick myofilaments are ∼3 µ long and overlap along ∼60% of their length in extended fibers and ∼80% in shortened fibers. There is virtually no endomysium and very little intracellular skeleton, and the cells are attached by desmosomes to one another rather than to connective tissue. Dense bodies are absent from the fibers and in their place are Z lines, which are truly linear rather than planar. Scattered among the predominant fibers are others, less orderly in arrangement, in which the SR is much less prominent and in which the thick filaments are thicker and longer and overlap to an even smaller degree. It is suggested that physiological differences between bloodworm and Ascaris muscles derive from differences in the proportion of series to parallel linkages between the contractile elements, differences in the amount and disposition of the SR, and differences in the impedance to shear within the myofibrils.

Multilaminar aggregates of sarcoplasmic reticulum in caudal muscle cells of an ascidian larva

1980 ◽  
Vol 58 (4) ◽  
pp. 538-542
Author(s):  
Michael J. Cavey
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Muscle Cells ◽  
Ascidian Larva ◽  
The Cross

The sarcoplasmic reticulum (SR) in caudal muscle cells of the larva of the polycitorid ascidian Distaplia occidentalis consists of perifibrillar cisternae and coextensive cisternal aggregates. The multilaminar aggregates resemble the interdigitated collars of perifibrillar SR which embrace the sarcomeric H-bands of the cross-striated myofibrils. Cisternae of the coextensive sarcoplasmic reticulum neither envelop the contractile myofilaments nor couple to the sarcolemma. Ultra-structural evidence is suggestive that the coextensive multilaminar aggregates are transient elements of the sarcoplasmic reticulum.

HAX-1: A multifaceted antiapoptotic protein localizing in the mitochondria and the sarcoplasmic reticulum of striated muscle cells

2010 ◽  
Vol 48 (6) ◽  
pp. 1266-1279 ◽  
Author(s):  
Solomon V. Yap ◽  
Elizabeth Vafiadaki ◽  
John Strong ◽  
Aikaterini Kontrogianni-Konstantopoulos
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Striated Muscle ◽  
Muscle Cells ◽  
Antiapoptotic Protein

scholarly journals Direct measurement of Ca2+ uptake and release by the sarcoplasmic reticulum of saponin permeabilized isolated smooth muscle cells.

1995 ◽  
Vol 106 (3) ◽  
pp. 467-484 ◽  
Author(s):  
M E Kargacin ◽  
G J Kargacin
Keyword(s):  
Smooth Muscle ◽  
Sarcoplasmic Reticulum ◽  
Smooth Muscle Cells ◽  
Single Cell ◽  
Striated Muscle ◽  
Muscle Cells ◽  
Intact Cells ◽  
Direct Measurements ◽  
Isolated Smooth Muscle Cells ◽  
Uptake And Release

To make direct measurements of Ca2+ uptake and release by the sarcoplasmic reticulum (SR) of isolated smooth muscle cells, a fluorometric method for monitoring Ca2+ uptake by striated muscle SR vesicles (Kargacin, M.E., C.R. Scheid, and T.W. Honeyman. 1988. American Journal of Physiology. 245:C694-C698) was modified. With the method, it was possible to make continuous measurements of SR function in saponin-skinned smooth muscle cells in suspension. Calcium uptake by the SR was inhibited by thapsigargin and sequestered Ca2+ could be released by Br-A23187 and thapsigargin. From the rate of Ca2+ uptake by the skinned cells and the density of cells in suspension, it was possible to calculate the Ca2+ uptake rate for the SR of a single cell. Our results indicate that the SR Ca2+ pump in smooth muscle cells can remove Ca2+ at a rate that is 45-75% of the rate at which Ca2+ is removed from the cytoplasm of intact cells during transient Ca2+ signals. From estimates of SR volume reported by others and our measurements of the amount of Ca2+ taken up by the skinned cells, we conclude that the SR of a single cell can store greater than 10 times the amount of Ca2+ needed to elicit a single transient contractile response.

A New Approach to the Demonstration of Oxidase-Localization Using Tannic Acid Or Catechin

1973 ◽  
Vol 31 ◽  
pp. 698-699
Author(s):  
V. Mizuhira ◽  
Y. Futaesaku
Keyword(s):  
Cross Section ◽  
Tannic Acid ◽  
Elastic Fiber ◽  
The Other ◽  
New Approach ◽  
Tissue Block ◽  
Active Reaction ◽  
The Cross

Previously we reported that tannic acid is a very effective fixative for proteins including polypeptides. Especially, in the cross section of microtubules, thirteen submits in A-tubule and eleven in B-tubule could be observed very clearly. An elastic fiber could be demonstrated very clearly, as an electron opaque, homogeneous fiber. However, tannic acid did not penetrate into the deep portion of the tissue-block. So we tried Catechin. This shows almost the same chemical natures as that of proteins, as tannic acid. Moreover, we thought that catechin should have two active-reaction sites, one is phenol,and the other is catechole. Catechole site should react with osmium, to make Os- black. Phenol-site should react with peroxidase existing perhydroxide.

Getting Jesus off the altar: Undoing atonement readings in Revelation

2021 ◽  
Vol 118 (1) ◽  
pp. 54-61
Author(s):  
Anna M. V. Bowden
Keyword(s):  
The Other ◽  
History Of ◽  
The Cross

The interpretive history of Revelation is overrun with descriptions of Jesus as a sacrificial lamb. Yet, John never uses the popular phrase to describe him. By drawing attention to four significant omissions in the text, I argue against atonement readings of “the Lamb” in Revelation. Revelation is not a theological treatise on the meaning of the cross. It feeds questions about power and violence and admonishes the seven churches against participation in their imperial context. John’s slaughtered lamb, therefore, does not evoke a paschal sacrifice; it points to Rome’s penchant for violence. Joining the other bloodied bodies in Revelation, the lamb’s blood further incriminates Rome. Everywhere one looks in John’s depiction of empire, violence lurks. Finally, the only altar in Revelation is the heavenly altar, and this altar is not a place for sacrifice. The heavenly altar is a place where the laments of the suffering are heard, a place for worshipping God, and a place where Rome will meet its judgment. John’s Jesus is not a self-sacrificing spiritual savior; he bears witness to the bloodthirsty, massacre-loving beast-of-all-beasts. Churches must choose their allegiance.

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