Mechanical and energy characteristics during shortening in isolated type-1 muscle fibres from Xenopus laevis studied at maximal and submaximal activation

An analysis has been performed of the native myosin isoenzyme com position of isolated skeletal muscle fibres from Xenopus laevis with welldefined isotonic contraction properties. Fast twitch ‘ white ’ (type 1) fibres contained three isomyosins; fast twitch ‘red ’ (type 2) fibres showed two major myosin bands with migration velocities very similar to those of the two slower bands in type 1. Slow twitch (type 3) fibres yielded a single, slowly migrating band as did slow tonic (type 5) fibres, whereas the myosin from type 4 (very slow twitch, ‘intermediate’) fibres migrated with a somewhat higher mobility. The results suggest that amphibian skeletal muscle may possess the principal fibre types found in mammals and birds.

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Twitch and Tetanic Tension during Culture of Mature Xenopus laevis Single Muscle Fibres

Archives of Physiology and Biochemistry ◽

10.1076/apab.109.5.410.11825 ◽

2001 ◽

Vol 109 (5) ◽

pp. 410-417 ◽

Cited By ~ 6

Author(s):

R.T. Jaspers ◽

H.M. Feenstra ◽

M.B.E. Lee-de Groot ◽

P.A. Huijing ◽

W.J. van der Laarse

Keyword(s):

Xenopus Laevis ◽

Muscle Fibres ◽

Single Muscle ◽

Tetanic Tension

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Metabolic changes with fatigue in different types of single muscle fibres of Xenopus laevis.

The Journal of Physiology ◽

10.1113/jphysiol.1992.sp019054 ◽

1992 ◽

Vol 448 (1) ◽

pp. 511-523 ◽

Cited By ~ 39

Author(s):

A S Nagesser ◽

W J van der Laarse ◽

G Elzinga

Keyword(s):

Xenopus Laevis ◽

Metabolic Changes ◽

Muscle Fibres ◽

Single Muscle ◽

Different Types

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Selective enhancement of bovine papillomavirus type 1 DNA replication in Xenopus laevis eggs by the E6 gene product

Molecular and Cellular Biology ◽

10.1128/mcb.9.2.406-414.1989 ◽

1989 ◽

Vol 9 (2) ◽

pp. 406-414

Author(s):

H Romanczuk ◽

W M Wormington

Keyword(s):

Dna Replication ◽

Xenopus Laevis ◽

Gene Product ◽

Mammalian Cells ◽

Xenopus Laevis Oocytes ◽

Bovine Papillomavirus ◽

In Vitro Synthesis ◽

E6 Gene ◽

E6 Protein

Genetic analyses of bovine papillomavirus type 1 (BPV-1) DNA in transformed mammalian cells have indicated that the E6 gene product is essential for the establishment and maintenance of a high plasmid copy number. In order to analyze the direct effect of the E6 protein on the replication of a BPV-1-derived plasmid, a cDNA containing the BPV-1 E6 open reading frame was subcloned into an SP6 vector for the in vitro synthesis of the corresponding mRNA. The SP6 E6 mRNA was injected into Xenopus laevis oocytes to determine the subcellular localization of the E6 gene product and to analyze the effect of the protein on BPV-1 DNA replication. SP6 E6 mRNA microinjected into stage VI oocytes was translated into a 15.5-kilodalton protein that was specifically immunoprecipitated by antibodies directed against the E6 gene product. The E6 protein preferentially accumulated in oocyte nuclei, a localization which is consistent with the replicative functions in which it has been implicated. The expression of E6 in replication-competent mature oocytes selectively enhanced the replication of a BPV-derived plasmid, indicating a direct role for this gene product in the control of BPV-1 DNA replication.

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Patterns of Myo-neural Junctions and Cholinesterase Activity in the Muscles of Tadpoles of Xenopus Laevis

Journal of Cell Science ◽

10.1242/jcs.s3-101.53.55 ◽

1960 ◽

Vol s3-101 (53) ◽

pp. 55-67

Author(s):

P. R. LEWIS ◽

A.F. W. HUGHES

Keyword(s):

Xenopus Laevis ◽

Convenient Method ◽

Azo Dye ◽

Cholinesterase Activity ◽

Muscle Fibres ◽

Striated Muscles ◽

Usual Type ◽

Special Adaptation ◽

Slow Type ◽

Axial Musculature

A simultaneous coupling azo dye technique has been used to reveal the distribution of cholinesterase activity in the musculature of the developing tadpole of Xenopus laevis. The use of inhibitors and a less convenient but more specific histochernical technique confirmed that only true cholinesterase distribution was being demonstrated; and a study of silver-impregnated material proved that this azo dye technique provides a very convenient method of following the development of the patterns of myo-neural junctions in the striated muscles of this tadpole. A wide variety of patterns is seen in the various muscles: in the axial musculature the muscle-fibres become innervated at their ends from myocommatal plexuses and never acquire endings along their length; broad muscular sheets, as in the walls of the branchial and abdominal cavities, are also first innervated terminally from the septa but later acquire secondary innervation is along the lengths of the fibres. These different patterns of innervation are correlated with the functions of the various types of muscle. It is suggested that terminal innervation may be a special adaptation to permit rapid establishment of neurogenic activity, the pattern of endings of the more usual type forming when the need for precisely co-ordinated reflexogenic activity arises. In some muscles, the azo dye technique reveals a profuse multiple innervation of the fibres which are assumed to be of the so-called ‘slow type’ known to exist in some amphibian muscles.

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Neurotoxin Merging: A Strategy Deployed by the Venom of the Spider Cupiennius salei to Potentiate Toxicity on Insects

Toxins ◽

10.3390/toxins12040250 ◽

2020 ◽

Vol 12 (4) ◽

pp. 250 ◽

Cited By ~ 1

Author(s):

Benjamin Clémençon ◽

Lucia Kuhn-Nentwig ◽

Nicolas Langenegger ◽

Lukas Kopp ◽

Steve Peigneur ◽

...

Keyword(s):

Xenopus Laevis ◽

Direct Interaction ◽

Structural Type ◽

Structure Type ◽

Open Loop ◽

Cytolytic Activity ◽

Xenopus Laevis Oocytes ◽

Cupiennius Salei

The venom of Cupiennius salei is composed of dozens of neurotoxins, with most of them supposed to act on ion channels. Some insecticidal monomeric neurotoxins contain an α-helical part besides their inhibitor cystine knot (ICK) motif (type 1). Other neurotoxins have, besides the ICK motif, an α-helical part of an open loop, resulting in a heterodimeric structure (type 2). Due to their low toxicity, it is difficult to understand the existence of type 2 peptides. Here, we show with the voltage clamp technique in oocytes of Xenopus laevis that a combined application of structural type 1 and type 2 neurotoxins has a much more pronounced cytolytic effect than each of the toxins alone. In biotests with Drosophila melanogaster, the combined effect of both neurotoxins was enhanced by 2 to 3 log units when compared to the components alone. Electrophysiological measurements of a type 2 peptide at 18 ion channel types, expressed in Xenopus laevis oocytes, showed no effect. Microscale thermophoresis data indicate a monomeric/heterodimeric peptide complex formation, thus a direct interaction between type 1 and type 2 peptides, leading to cell death. In conclusion, peptide mergers between both neurotoxins are the main cause for the high cytolytic activity of Cupiennius salei venom.

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