ULTRASTRUCTURE OF BARNACLE GIANT MUSCLE FIBERS

Increasing use of barnacle giant muscle fibers for physiological research has prompted this investigation of their fine structure. The fibers are invaginated by a multibranched system of clefts connecting to the exterior and filled with material similar to that of the basement material of the sarcolemmal complex. Tubules originate from the surface plasma membrane at irregular sites, and also from the clefts They run transversely, spirally, and longitudinally, making many diadic and some triadic contacts with cisternal sacs of the longitudinal sarcoplasmic reticulum. The contacts are not confined to any particular region of the sarcomere. The tubules are wider and their walls are thicker at points of contact with Z material. Some linking of the Z regions occurs across spaces within the fiber which contain large numbers of glycogen particles. A-band lengths are extremely variable, in the range 2.2 µm–20.3 µm (average 5.2 µm) Individual thick filaments have thin (110 Å) hollow regions alternating with thick (340 Å) solid ones. Bridges between thick filaments occur at random points and are not concentrated into an M band The thin:thick filament ratio is variable in different parts of a fiber, from 3:1 to 6:1. Z bands are basically perforated, but the number of perforations may increase during contraction.

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New insights into the morphology and evolution of the ventral pharynx and jaws in Histriobdellidae (Eunicida, Annelida)

Zoological Letters ◽

10.1186/s40851-020-00168-2 ◽

2020 ◽

Vol 6 (1) ◽

Author(s):

Alexander Tzetlin ◽

Nataliya Budaeva ◽

Elena Vortsepneva ◽

Conrad Helm

Keyword(s):

Fine Structure ◽

3D Reconstruction ◽

Muscle Fibers ◽

Comparative Analyses ◽

Maxillary Protraction ◽

Jaw Apparatus ◽

Different Parts ◽

Comprehensive Study

AbstractThe jaw apparatus in several annelid families represents a powerful tool for systematic approaches and evolutionary investigations. Nevertheless, for several taxa, this character complex has scarcely been investigated, and complete comparative analyses of all annelid jaws are lacking. In our comprehensive study, we described the fine structure of the jaw apparatus and the ventral pharyngeal organ (VPO) in Histriobdella homari – a minute ectocommensal of lobsters putatively belonging to the Eunicida – using different comparative morphological approaches, including SEM, TEM, CLSM and subsequent 3D reconstruction. The H. homari jaw apparatus is composed of ventral paired mandibles and dorsal symmetrical maxillae consisting of numerous dental plates, ventral carriers and an unpaired dorsal rod, and the general assemblage and arrangement of the different parts are highly comparable to those of other eunicid families. The jaw ultrastructure of histriobdellids resembles that of the families Dorvilleidae and (juvenile) Onuphidae. Furthermore, our data reveal that in the process of development of the jaw apparatus, the mandibles, maxillae II and unpaired dorsal rod are formed first, and the remaining maxillae and ventral carriers appear later. Notably, the muscular apparatus differs from that in Dorvilleidae and Onuphidae in terms of the number and arrangement of muscle fibers encompassing the jaws – not only because of the very small size of Histriobdella but also because histriobdellid maxillary protraction occurs due to straightening of the dorsal rod and thus requires a different muscular scaffold. Based on our investigations, the arrangement of the muscular apparatus of the jaws, the presence of paired ventral carriers and the dorsal rod, and the morphology of the ventral pharyngeal organ represent a histriobdellid autapomorphy. Our datasets form a basis for further comparative analyses to elucidate the evolution of Eunicida and jaw-bearing Annelida.

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Fine structure of transverse tubules and the sarcoplasmic reticulum at the myotendinous junction of stretched muscle fibers of the rat

Microscopy Research and Technique ◽

10.1002/jemt.1070240306 ◽

1993 ◽

Vol 24 (3) ◽

pp. 281-286 ◽

Cited By ~ 4

Author(s):

Masaki Sonoda ◽

Hideshige Moriya ◽

Yutaka Shimada

Keyword(s):

Fine Structure ◽

Sarcoplasmic Reticulum ◽

Muscle Fibers ◽

Myotendinous Junction ◽

Transverse Tubules

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ULTRASTRUCTURAL FEATURES OF CRAYFISH PHASIC AND TONIC MUSCLE FIBERS

Canadian Journal of Zoology ◽

10.1139/z67-076 ◽

1967 ◽

Vol 45 (5) ◽

pp. 601-606 ◽

Cited By ~ 53

Author(s):

S. S. Jahromi ◽

H. L. Atwood

Keyword(s):

Fine Structure ◽

Electron Microscope ◽

Transverse Section ◽

Muscle Fibers ◽

Orconectes Virilis ◽

Neuromuscular Synapses ◽

Thick Filaments ◽

Tonic Muscle ◽

Extensor Muscles

Phasic and tonic muscle fibers from the abdominal extensor muscles of the crayfish, Procambarus clarki and Orconectes virilis, were examined for differences in fine structure with the electron microscope. The myofibrils of the two types of fiber were similar in size as seen in transverse section, unlike those in vertebrate twitch and tonus fibers. The ratio of thin to thick filaments was about 5:1 in tonic fibers and 3:1 in phasic fibers. Neuromuscular synapses in tonic fibers were enclosed by arms of noncontractile sarcoplasm, whereas the synapses seen in phasic fibers lacked this feature.

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Immunogold-labeled L-type Calcium Channels are Clustered in the Surface Plasma Membrane Overlying Junctional Sarcoplasmic Reticulum in Guinea-pig Myocytes—Implications for Excitation–contraction Coupling in Cardiac Muscle

Journal of Molecular and Cellular Cardiology ◽

10.1006/jmcc.2000.1230 ◽

2000 ◽

Vol 32 (11) ◽

pp. 1981-1994 ◽

Cited By ~ 32

Author(s):

David V Gathercole ◽

David J Colling ◽

Jeremy N Skepper ◽

Yoshiko Takagishi ◽

Allan J Levi ◽

...

Keyword(s):

Plasma Membrane ◽

Sarcoplasmic Reticulum ◽

Guinea Pig ◽

Calcium Channels ◽

Cardiac Muscle ◽

Surface Plasma ◽

Excitation Contraction Coupling ◽

Contraction Coupling ◽

Junctional Sarcoplasmic Reticulum

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BIOASSAY CHARACTERISTICS OF INDIVIDUAL URINARY GONADOTROPHIN EXTRACTS

Acta Endocrinologica ◽

10.1530/acta.0.0420214 ◽

1963 ◽

Vol 42 (2) ◽

pp. 214-224

Author(s):

Raymond C. Mellinger ◽

Jalileh A. Mansour ◽

Richmond W. Smith

Keyword(s):

Reference Material ◽

Young Women ◽

Reference Standard ◽

General Acceptance ◽

Modifying Factors ◽

Large Numbers ◽

The World ◽

Quantitative Bioassay ◽

Different Parts ◽

Age And Sex

ABSTRACT A reference standard is widely sought for use in the quantitative bioassay of pituitary gonadotrophin recovered from urine. The biologic similarity of pooled urinary extracts obtained from large numbers of subjects, utilizing groups of different age and sex, preparing and assaying the materials by varying techniques in different parts of the world, has lead to a general acceptance of such preparations as international gonadotrophin reference standards. In the present study, however, the extract of pooled urine from a small number of young women is shown to produce a significantly different bioassay response from that of the reference materials. Gonadotrophins of individual subjects likewise varied from the multiple subject standards in many instances. The cause of these differences is thought to be due to the modifying influence of non-hormonal substances extracted from urine with the gonadotrophin and not necessarily to variations in the gonadotrophins themselves. Such modifying factors might have similar effects in a comparative assay of pooled extracts contributed by many subjects, but produce significant variations when material from individual subjects is compared. It is concluded that the expression of potency of a gonadotrophic extract in terms of pooled reference material to which it is not essentially similar may diminish rather than enhance the validity of the assay.

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Carbonic Anhydrases in Photosynthesizing Cells of C3 Higher Plants

Metabolites ◽

10.3390/metabo9040073 ◽

2019 ◽

Vol 9 (4) ◽

pp. 73 ◽

Cited By ~ 5

Author(s):

Lyudmila Ignatova ◽

Natalia Rudenko ◽

Elena Zhurikova ◽

Maria Borisova-Mubarakshina ◽

Boris Ivanov

Keyword(s):

Plasma Membrane ◽

Carbonic Anhydrase ◽

Environmental Conditions ◽

Organic Molecules ◽

Higher Plants ◽

C3 Plants ◽

Coherent System ◽

Carbonic Anhydrases ◽

Chloroplast Stroma ◽

Different Parts

The review presents data on the location, nature, properties, number, and expression of carbonic anhydrase genes in the photosynthesizing cells of C3 plants. The available data about the presence of carbonic anhydrases in plasma membrane, cytoplasm, mitochondria, chloroplast stroma and thylakoids are scrutinized. Special attention was paid to the presence of carbonic anhydrase activities in the different parts of thylakoids, and on collation of sources of these activities with enzymes encoded by the established genes of carbonic anhydrases. The data are presented to show that the consistent incorporation of carbonic anhydrases belonging to different families of these enzymes forms a coherent system of CO2 molecules transport from air to chloroplasts in photosynthesizing cells, where they are included in organic molecules in the carboxylation reaction. It is discussed that the manifestation of the activity of a certain carbonic anhydrase depends on environmental conditions and the stage of ontogenesis.

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The amino-terminal 200 amino acids of the plasma membrane Na+,K+-ATPase alpha subunit confer ouabain sensitivity on the sarcoplasmic reticulum Ca(2+)-ATPase.

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.90.19.8881 ◽

1993 ◽

Vol 90 (19) ◽

pp. 8881-8885 ◽

Cited By ~ 27

Author(s):

T. Ishii ◽

K. Takeyasu

Keyword(s):

Amino Acids ◽

Plasma Membrane ◽

Sarcoplasmic Reticulum ◽

Alpha Subunit ◽

Amino Terminal ◽

Ouabain Sensitivity

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THE FINE STRUCTURE OF ASTROCYTES IN THE CEREBRAL CORTEX AND THEIR RESPONSE TO FOCAL INJURY PRODUCED BY HEAVY IONIZING PARTICLES

The Journal of Cell Biology ◽

10.1083/jcb.25.2.141 ◽

1965 ◽

Vol 25 (2) ◽

pp. 141-157 ◽

Cited By ~ 183

Author(s):

David S. Maxwell ◽

Lawrence Kruger

Keyword(s):

Cerebral Cortex ◽

Fine Structure ◽

Electron Microscope ◽

Reactive Astrocytes ◽

Lipid Bodies ◽

Particle Irradiation ◽

Fibrous Astrocytes ◽

Primitive Forms ◽

Focal Injury ◽

Glycogen Particles

Normal and reactive astrocytes in the cerebral cortex of the rat have been studied with the electron microscope following focal alpha particle irradiation. The presence of glycogen and approximately 60-A fibrils identify astrocyte cytoplasm in formalin-perfused tissue. The glycogen particles facilitate the identification of small processes and subpial and perivascular end-feet. Both protoplasmic and fibrous astrocytes contain cytoplasmic fibrils and should be distinguished on the basis of the configuration of their processes and their distribution. Acutely reactive astrocytes are characterized by a marked increase in the number of glycogen granules and mitochondria from the first day after irradiation. These cells later hypertrophy and accumulate lipid bodies and increased numbers of cytoplasmic fibrils. The glial "scar" consists of a greatly expanded volume of astrocyte cytoplasm filled with fibrils and displays no signs of astrocyte death, reversion to primitive forms, or extensive multiplication.

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