The Structure and Operation of the Obliquely Striated Supercontractile Somatic Muscles in Nematodes.

1983 ◽  
Vol 31 (5) ◽  
pp. 677 ◽  
Author(s):  
WG Inglis
Keyword(s):  
Striated Muscle ◽  
Striated Muscles ◽  
Insect Larvae ◽  
Hydrostatic Skeleton ◽  
Wide Range ◽  
Somatic Muscles

The structure of nematode somatic muscles is reviewed. They are obliquely striated and, therefore, supercontractile because they change in length to an exceptional extent by both myofilament interdigitation and shearing. A model is developed which shows that shearing is generated by interdigitation under specified structural conditions. It is concluded that the ability to supercontract is functionally associated with a hydrostatic skeleton, because obliquely striated muscles occur in a wide range of unrelated Phyla and a functionally identical muscle has evolved from cross-striated muscle in other animals with a hydrostatic skeleton, particularly certain insect larvae. Two, possibly 3, morphologically distinct groups of muscles exist in the Nematoda which correspond to the Classes Enoplea, Rhabditea and Chromadorea. Parallel sequences of change occur in the first 2, in which the contractile layer increases in area, the sarcomeres become smaller, and the Z-system more regular. Descriptive terms are redefined, thus: platymyarian, quasi-platymyarian, shallow coelomyarian, and coelomyarian occur in Rhabditea; cubomyarian, regular cubomyarian, and stratimyarian occur in Enoplea; and a characteristic chromadorid-circomyarian is known from 2 Chromadorea. The structure of the muscles corresponds well to the higher nematode classification, except in the Order Spirurida which may have arisen from the Enoplea and not the Rhabditea as generally accepted.

Myosin light chain phosphorylation in vertebrate striated muscle: regulation and function

1993 ◽  
Vol 264 (5) ◽  
pp. C1085-C1095 ◽  
Author(s):  
H. L. Sweeney ◽  
B. F. Bowman ◽  
J. T. Stull
Keyword(s):  
Skeletal Muscle ◽  
Light Chain ◽  
Myosin Light Chain ◽  
Striated Muscle ◽  
Low Frequency ◽  
Force Production ◽  
Thick Filament ◽  
Striated Muscles ◽  
Wide Range ◽  
Cross Bridges

The regulatory light chain of myosin (RLC) is phosphorylated in striated muscles by Ca2+/calmodulin-dependent myosin light chain kinase. Unique biochemical and cellular properties of this phosphorylation system in fast-twitch skeletal muscle maintain RLC in the phosphorylated form for a prolonged period after a brief tetanus or during low-frequency repetitive stimulation. This phosphorylation correlates with potentiation of the rate of development and maximal extent of isometric twitch tension. In skinned fibers, RLC phosphorylation increases force production at low levels of Ca2+ activation, via a leftward shift of the force-pCa relationship, and increases the rate of force development over a wide range of activation levels. In heart and slow-twitch skeletal muscle, the functional consequences of RLC phosphorylation are probably similar, and the primary physiological determinants are phosphorylation and dephosphorylation properties unique to each muscle. The mechanism for these physiological responses probably involves movement of the phosphorylated myosin cross bridges away from the thick-filament backbone. The movement of cross bridges may also contribute to the regulation of myosin interactions with actin in vertebrate smooth and invertebrate striated muscles.

Linear electrical properties of striated muscle fibres observed with intracellular electrodes

1964 ◽  
Vol 160 (978) ◽  
pp. 69-123 ◽  
Keyword(s):  
Electrical Properties ◽  
Striated Muscle ◽  
Surface Membrane ◽  
Fibre Surface ◽  
Step Function ◽  
Muscle Fibres ◽  
Appreciable Effect ◽  
Current Application ◽  
Current Path ◽  
Wide Range

The linear electrical properties of muscle fibres have been examined using intracellular electrodes for a. c. measurements and analyzing observations on the basis of cable theory. The measurements have covered the frequency range 1 c/s to 10 kc/s. Comparison of the theory for the circular cylindrical fibre with that for the ideal, one-dimensional cable indicates that, under the conditions of the experiments, no serious error would be introduced in the analysis by the geometrical idealization. The impedance locus for frog sartorius and crayfish limb muscle fibres deviates over a wide range of frequencies from that expected for a simple model in which the current path between the inside and the outside of the fibre consists only of a resistance and a capacitance in parallel. A good fit of the experimental results on frog fibres is obtained if the inside-outside admittance is considered to contain, in addition to the parallel elements R m = 3100 Ωcm 2 and C m = 2.6 μF/cm 2 , another path composed of a resistance R e = 330 Ωcm 2 in series with a capacitance C e = 4.1 μF/cm 2 , all referred to unit area of fibre surface. The impedance behaviour of crayfish fibres can be described by a similar model, the corresponding values being R m = 680 Ωcm 2 , C m = 3.9 μF/cm 2 , R e = 35 Ωcm 2 , C e = 17 μF/cm 2 . The response of frog fibres to a step-function current (with the points of voltage recording and current application close together) has been analyzed in terms of the above two-time constant model, and it is shown that neglecting the series resistance would have an appreciable effect on the agreement between theory and experiment only at times less than the halftime of rise of the response. The elements R m and C m are presumed to represent properties of the surface membrane of the fibre. R e and C e are thought to arise not at the surface, but to be indicative of a separate current path from the myoplasm through an intracellular system of channels to the exterior. In the case of crayfish fibres, it is possible that R e (when referred to unit volume) would be a measure of the resistivity of the interior of the channels, and C e the capacitance across the walls of the channels. In the case of frog fibres, it is suggested that the elements R e , C e arise from the properties of adjacent membranes of the triads in the sarcoplasmic reticulum . The possibility is considered that the potential difference across the capacitance C e may control the initiation of contraction.

Phylogenetic implications of the superfast myosin in extraocular muscles

2002 ◽  
Vol 205 (15) ◽  
pp. 2189-2201 ◽  
Author(s):  
Fred Schachat ◽  
Margaret M. Briggs
Keyword(s):  
Myosin Heavy Chain ◽  
Gene Cluster ◽  
Heavy Chain ◽  
Striated Muscle ◽  
Extraocular Muscles ◽  
Chromosome 17 ◽  
Striated Muscles ◽  
Chromosome 11 ◽  
Phylogenetic Implications ◽  
Myh Gene

SUMMARY Extraocular muscle exhibits higher-velocity and lower-tension contractions than other vertebrate striated muscles. These distinctive physiological properties are associated with the expression of a novel extraocular myosin heavy chain (MYH). Encoded by the MYH13 gene, the extraocular myosin heavy chain is a member of the fast/developmental MYH gene cluster on human chromosome 17 and the syntenic MYH cluster on mouse chromosome 11. Comparison of cDNA sequences reveals that MYH13 also encodes the atypical MYH identified in laryngeal muscles, which have similar fast contractile properties. Comparing the MYH13 sequence with the other members of the fast/developmental cluster, the slow/cardiac MYH genes and two orphan skeletal MYH genes in the human genome provides insights into the origins of specialization in striated muscle myosins. Specifically, these studies indicate (i) that the extraocular myosin is not derived from the adult fast skeletal muscle myosins, but was the first member of the fast/developmental MYH gene cluster to diverge and specialize, (ii) that the motor and rod domains of the MYH13 have evolved under different selective pressures and (iii) that the MYH13 gene has been largely insulated from genomic events that have shaped other members of the fast/developmental cluster. In addition, phylogenetic footprinting suggests that regulation of the extraocular MYH gene is not governed primarily by myogenic factors, but by a hierarchical network of regulatory factors that relate its expression to the development of extraocular muscles.

Technology of production of biopesticides based on Bacillus thuringiensis

2021 ◽  
Vol 9 (16) ◽  
pp. 28-38
Author(s):  
Anatolii Bezusov ◽  
◽  
Valentyna Krutiakova ◽  
Olena Myroshnichenko ◽  
Nataliia Dotsenko ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Corn Oil ◽  
Raw Materials ◽  
Culture Fluid ◽  
Scientific Work ◽  
Insect Larvae ◽  
Effective Prevention ◽  
Research Results ◽  
Wide Range ◽  
Vegetable Raw Materials

Subject of research. Biopesticides are based on live cultures of specially selected beneficial microorganisms with controlled properties. They have a pronounced phytoprotective and stimulating effect, thus providing effective prevention and protection of plants from diseases. The obtained biological product increases productivity, improves the quality and structure of the crop, does not accumulate in plants, which allows to obtain environmentally friendly agricultural products and does not harm the environment. Among the large number of bacteria, as a source of microbiological insecticide is Bacillus thuringiensis, which infects lepidopteran pests and leads to their death. Preparations based on this strain are effective when used in low concentrations of solutions. The Bacillus thuringiensis strain produces several toxins with insecticidal action, including β-exotoxin and δ-endotoxin. Toxic effect is manifested and leads to paralysis of the intestinal tract of parasites. Preparations β-exotoxin and δ-endotoxin are obtained by culturing Bacillus thuringiensis bacteria in a liquid medium. The scientific work proposes a method of industrial production using by-products of vegetable raw materials, which makes it economically feasible to use such substrates. The purpose of the study is the development of technology, formulation of nutrient medium, process parameters for the cultivation of bacteria of the genus Bacillus thuringiensis and obtaining a culture fluid containing substances of the class of biopesticides. Methods. Standard and generally accepted methods of research of bioproducts in biotechnology. The formation of bioinsecticides was established by hydrolysis methods, followed by determination of the component of β-exotoxin – ribose, the formation of octagonal crystals of exotoxin – by microscopic method. Research results. Three variants of nutrient media, which include yeast-polysaccharide complex: corn flour, corn oil, yeast autolysate were developed. The parameters of the bacterial cultivation process were studied. The final product is a paste or powder with a titer of 35 .109 spores in 1 g of the bioproduct. Scope of research results. Microbiological preparations based on Bacillus thuringiensis are highly specific and act only on insect larvae from the classes Lepidoptera and Diptera. The resulting biopesticide can be used against pests of a wide range of vegetable and fruit crops.

scholarly journals A distinct cardiopharyngeal mesoderm genetic hierarchy establishes antero-posterior patterning of esophagus striated muscle

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Glenda Comai ◽  
Eglantine Heude ◽  
Sebastian Mella ◽  
Sylvain Paisant ◽  
Francesca Pala ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Striated Muscle ◽  
Striated Muscles ◽  
Food Ingestion ◽  
Loss Of Function ◽  
Pharmacological Studies ◽  
Posterior Migration ◽  
Functional Relevance ◽  
Genetic Signatures ◽  
Genetic Hierarchy

In most vertebrates, the upper digestive tract is composed of muscularized jaws linked to the esophagus that permits food ingestion and swallowing. Masticatory and esophagus striated muscles (ESM) share a common cardiopharyngeal mesoderm (CPM) origin, however ESM are unusual among striated muscles as they are established in the absence of a primary skeletal muscle scaffold. Using mouse chimeras, we show that the transcription factors Tbx1 and Isl1 are required cell-autonomously for myogenic specification of ESM progenitors. Further, genetic loss-of-function and pharmacological studies point to MET/HGF signaling for antero-posterior migration of esophagus muscle progenitors, where Hgf ligand is expressed in adjacent smooth muscle cells. These observations highlight the functional relevance of a smooth and striated muscle progenitor dialogue for ESM patterning. Our findings establish a Tbx1-Isl1-Met genetic hierarchy that uniquely regulates esophagus myogenesis and identify distinct genetic signatures that can be used as framework to interpret pathologies arising within CPM derivatives.

The superfast extraocular myosin (MYH13) is localized to the innervation zone in both the global and orbital layers of rabbit extraocular muscle

2002 ◽  
Vol 205 (20) ◽  
pp. 3133-3142 ◽  
Author(s):  
Margaret M. Briggs ◽  
Fred Schachat
Keyword(s):  
Eye Movements ◽  
Striated Muscle ◽  
Contractile Activity ◽  
Regional Distribution ◽  
Motor Units ◽  
Molecular Heterogeneity ◽  
Ocular Motility ◽  
Fiber Types ◽  
Striated Muscles ◽  
Innervation Zone

SUMMARY Extraocular muscles (EOMs) are the most molecularly heterogeneous and physiologically diverse mammalian striated muscles. They express the entire array of striated muscle myosins, including a specialized myosin heavy chain MYH13, which is restricted to extraocular and laryngeal muscles. EOMs also exhibit a breadth of contractile activity, from superfast saccades to slow tracking and convergence movements. These movements are accomplished by the action of six ultrastructurally defined fiber types that differ from the type IIa, IIb, IIx and I fibers found in other skeletal muscles. Attempts to associate different eye movements with either the expression of different myosins or the activity of particular EOM fiber types are complicated by the molecular heterogeneity of several of the fiber types, and by electromyography studies showing that the majority of extraocular motor units participate in both fast and slow eye movements. To better understand the role of MYH13 in ocular motility, we generated MYH13-sequence-specific antibodies and used SDS-PAGE to quantify the regional distribution of myosin in EOM and to characterize its heterogeneity in single fibers. These studies demonstrate that MYH13 is preferentially expressed in the majority of orbital and global fibers in the central innervation zone of rabbit EOM. Many individual fibers express MYH13 with the fast IIb myosin and varying amounts of IIx myosin. The differential localization of MYH13, coupled with specialization of the sarcoplasmic reticulum and thin filament systems, probably explains how activation of the endplate band region enables the majority of EOM fibers to contribute to superfast contractions.

Caenorhabditis elegans twist plays an essential role in non-striated muscle development

Development ◽  
2000 ◽  
Vol 127 (10) ◽  
pp. 2041-2051 ◽  
Author(s):  
A.K. Corsi ◽  
S.A. Kostas ◽  
A. Fire ◽  
M. Krause
Keyword(s):  
Caenorhabditis Elegans ◽  
Essential Role ◽  
Muscle Development ◽  
Target Genes ◽  
Striated Muscle ◽  
Egg Laying ◽  
Bhlh Transcription Factor ◽  
Striated Muscles ◽  
Downstream Target ◽  
Mesodermal Development

The basic helix-loop-helix (bHLH) transcription factor Twist plays a role in mesodermal development in both invertebrates and vertebrates. In an effort to understand the role of the unique Caenorhabditis elegans Twist homolog, hlh-8, we analyzed mesodermal development in animals with a deletion in the hlh-8 locus. This deletion was predicted to represent a null allele because the HLH domain is missing and the reading frame for the protein is disrupted. Animals lacking CeTwist function were constipated and egg-laying defective. Both of these defects were rescued in transgenic mutant animals expressing wild-type hlh-8. Observing a series of mesoderm-specific markers allowed us to characterize the loss of hlh-8 function more thoroughly. Our results demonstrate that CeTwist performs an essential role in the proper development of a subset of mesodermal tissues in C. elegans. We found that CeTwist was required for the formation of three out of the four non-striated enteric muscles born in the embryo. In contrast, CeTwist was not required for the formation of the embryonically derived striated muscles. Most of the post-embryonic mesoderm develops from a single lineage. CeTwist was necessary for appropriate patterning in this lineage and was required for expression of two downstream target genes, but was not required for the expression of myosin, a marker of differentiation. Our results suggest that mesodermal patterning by Twist is an evolutionarily conserved function.

scholarly journals Morphological changes in the fast vs slow fiber profiles of the urethras of diabetic pregnant rats

2011 ◽  
Vol 25 (1) ◽  
pp. 9 ◽  
Author(s):  
Gabriela Marini ◽  
Angélica M. Pascon Barbosa ◽  
Débora C. Damasceno ◽  
Selma M. Michelin Matheus ◽  
Rodrigo De Aquino Castro ◽  
...  
Keyword(s):  
Striated Muscle ◽  
Morphological Changes ◽  
Fiber Type ◽  
Normal Function ◽  
Striated Muscles ◽  
Pregnant Rats ◽  
Morphological Alterations ◽  
Female Wistar Rats ◽  
Urethral Striated Muscle ◽  
Diabetes And Pregnancy

<em>Background</em>. This study was undertaken to test the hypothesis that diabetes and pregnancy detrimentally affect the normal function of urethral striated muscles in rats, providing a model for additional studies related to urinary incontinence. The aim of this study was to evaluate morphological alterations in the urethral striated muscles of diabetic pregnant rats. <em>Design and methods. </em>Twenty female Wistar rats were distributed into four experimental groups of five rats as follows: virgin, pregnant, diabetic virgin, and diabetic pregnant. Diabetes was induced using streptozotocin administration (40 mg/kg i.v.). The rats were lethally anesthetized, and the urethra and vagina were extracted as a unit. Cryostat sections (6 µm thick) were cut and stained with hematoxylin-eosin, and immunohistochemical procedures were performed and subjected to morphological and semi quantitative analysis. <em>Results</em>. The urethral striated muscle from the diabetic pregnant rats presented with the following variations: thinning and atrophy, disorganization and disruption associated with the colocalization of fast and slow fibers and a steady decrease in the proportion of fast <em>vs</em> slow fibers. <em>Conclusion</em>. Diabetes and pregnancy impair the urethral striated muscle and alter its fiber type distribution.

scholarly journals Changes in thick filament length in Limulus striated muscle.

1977 ◽  
Vol 75 (2) ◽  
pp. 366-380 ◽  
Author(s):  
M M Dewey ◽  
B Walcott ◽  
D E Colflesh ◽  
H Terry ◽  
R J Levine
Keyword(s):  
Horseshoe Crab ◽  
Striated Muscle ◽  
Thick Filament ◽  
Filament Length ◽  
Thin Filaments ◽  
Thick Filaments ◽  
Wide Range ◽  
The Difference

Here we describe the change in thick filament length in striated muscle of Limulus, the horseshoe crab. Long thick filaments (4.0 microns) are isolated from living, unstimulated Limulus striated muscle while those isolated from either electrically or K+-stimulated fibers are significantly shorter (3.1 microns) (P less than 0.001). Filaments isolated from muscle glycerinated at long sarcomere lengths are long (4.4 microns) while those isolated from muscle glycerinated at short sarcomere lengths are short (2.9 microns) and the difference is significant (P less than 0.001). Thin filaments are 2.4 microns in length. The shortening of thick filaments is related to the wide range of sarcomere lengths exhibited by Limulus telson striated muscle.

scholarly journals THE PATHOGENESIS OF WAXY DEGENERATION OF STRIATED MUSCLES (ZENKER'S DEGENERATION)

1909 ◽  
Vol 11 (1) ◽  
pp. 1-9 ◽  
Author(s):  
H. Gideon Wells
Keyword(s):  
Lactic Acid ◽  
Striated Muscle ◽  
Negative Evidence ◽  
Striated Muscles ◽  
Positive Evidence ◽  
Striated Muscle Fibers ◽  
Positive Results ◽  
Stimulation Of

In view of theoretical deductions and the positive results obtained in the above experiments, it would seem probable that the production of waxy degeneration depends upon the action of lactic acid which is formed by the living muscle under the stimulation of infecting bacteria or their toxins, the formation of large amounts of lactic acid and its accumulation being perhaps favored by defective circulation through the injured muscle. The hyaline transformation of muscle acted upon by lactic acid is analogous to the swelling of fibrin placed in dilute acids. This view is supported by both negative and positive experimental evidence—the negative evidence being that simple anemic necrosis, aseptic or antiseptic autolysis whether in vivo or in vitro, or the action of bacteria of various sorts on muscle in vitro, are all incapable of causing changes in muscle cells resembling those characteristic of waxy or hyaline degeneration of striated muscle. The positive evidence consists in the demonstration that lactic acid, even in dilutions comparable to the amounts that can be formed in living muscle, can produce a similar or identical waxy transformation of the striated muscle fibers, both in vitro and in vivo; and also the observation that muscles stimulated to exhaustion, under which condition lactic acid is known to accumulate in the muscle, show microscopically changes identical with those of Zenker's waxy degeneration.

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