The developmental morphology of <i>Torpedo marmorata</i>: Electric organ—electrogenic phase

Fox, Geoffrey; Richardson, Guy P.

doi:10.1002/cne.901850205

Cited by 61 publications

(22 citation statements)

References 28 publications

(3 reference statements)

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“…The electrocytes from both species are individually encapsulated in a loose connective tissue network. In R. erinacea they form columns similar to those seen in the T. marmorata electric organ (Fox and Richardson 1979) whereas in R. undulata they form a more loosely organized 'columnar' arrangement ( Fig. 1).…”

Section: A General Observations Of the Electric Organs Of Raja Undulmentioning

confidence: 89%

Morphological, physiological and biochemical observations on skate electric organ

1990

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The electric organs of two species of skate have been examined morphologically, physiologically and biochemically. They can be easily dissociated into innervated or denervated component electrocytes by a Torpedo Ringer's solution containing 1% collagenase. Collagenase treatment did not, however, separate the Schwann cell cover capping the synaptosomes. Isolated electrocytes generate normal MEPP frequencies and show evoked responses for two days in Torpedo Ringer's. The nerve terminals retain excitability and transmitter release properties up to the time of separation. Since isolated terminals and denervated electrocytes show normal ultrastructural characteristics for up to 12 h, the skate electric organ provides several preparations which are not attainable with Torpedo tissue. Acetylcholine (ACh) content of supernatant fractions containing the synaptosomes was comparable to that found in Torpedo (sps.). Collagenase specifically eliminates the basal lamina associated with the synaptic junctional region. Neuronal cell death and synaptic terminal degeneration were also noted in the adult organs of both species. The skate electric organ is ideally suited for the study of cholinergic development and transmission.

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Section: A General Observations Of the Electric Organs Of Raja Undulmentioning

confidence: 89%

Morphological, physiological and biochemical observations on skate electric organ

1990

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“…They still have to undergo a significant maturation (40). Most of the AcChoR is already restricted to the ventral electrocyte surface but its local concentration has not yet reached the adult value (41).…”

Section: Discussionmentioning

confidence: 99%

Production and characterization of a monoclonal antibody directed against the 43,000-dalton v1 polypeptide from Torpedo marmorata electric organ.

Nghiêm¹,

Cartaud²,

Dubreuil³

et al. 1983

Proc. Natl. Acad. Sci. U.S.A.

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Subsynaptic membrane fragments prepared from Torpedo marmorata electric organ contain, in addition to the acetylcholine receptor polypeptides, a major protein band of apparent molecular mass 43,000 daltons. On two-dimensional gels, this band yields three spots referred to as v1, v2, and V3. Monoclonal antibodies against the 43,000-dalton proteins were developed in CBA mice. One of them reacted exclusively with the vP polypeptide but not with p2 and v3. Staining by the "immunogold" reaction followed by observation by electron microscopy showed that this antibody exclusively labeled the innervated membrane of T. marmorata electroplaque on its cytoplasmic face. Electroblots of onedimensional gels of membrane preparations from 80-mm embryo electric organ were prepared. After reaction with the anti-vP monoclonal antibody, a strongly stained 43,000-dalton band was revealed.The acetylcholine receptor (AcChoR) protein (1) makes densely packed and stable aggregates in the subsynaptic membrane of the adult neuromuscular junction and of the electromotor synapse. This supramolecular organization develops during embryogenesis from a diffuse and labile distribution of AcChoR molecules present in the membrane of the noninnervated myotube or electrocyte. The mechanisms postulated to account for this important morphogenetic step (for refs., see ref.

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“…MRF expression has also been reported in the musclederived cells of EOs in electric fishes. The EOs of the strongly electric elasmobranch fish Torpedo californica and T. ocellata contain transcripts for MyoD, MRF4 and Myf5 (Asher et al, 1994;Neville and Schmidt, 1992), but they lack myofibrillar structures and many sarcomeric proteins (Fox and Richardson, 1978;Fox and Richardson, 1979;Mate et al, 2011). These data provide strong evidence in support of a myogenic program that likely involves the expression of additional factors and signaling pathways that interact with MRFs.…”

Section: Discussionmentioning

confidence: 92%

Mechanisms of muscle gene regulation in the electric organ ofSternopygus macrurus

Güth

Pinch

Unguez

2013

Journal of Experimental Biology

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SummaryAnimals perform a remarkable diversity of movements through the coordinated mechanical contraction of skeletal muscle. This capacity for a wide range of movements is due to the presence of muscle cells with a very plastic phenotype that display many different biochemical, physiological and morphological properties. What factors influence the maintenance and plasticity of differentiated muscle fibers is a fundamental question in muscle biology. We have exploited the remarkable potential of skeletal muscle cells of the gymnotiform electric fish Sternopygus macrurus to trans-differentiate into electrocytes, the non-contractile electrogenic cells of the electric organ (EO), to investigate the mechanisms that regulate the skeletal muscle phenotype. In S. macrurus, mature electrocytes possess a phenotype that is intermediate between muscle and non-muscle cells. How some genes coding for muscle-specific proteins are downregulated while others are maintained, and novel genes are upregulated, is an intriguing problem in the control of skeletal muscle and EO phenotype. To date, the intracellular and extracellular factors that generate and maintain distinct patterns of gene expression in muscle and EO have not been defined. Expression studies in S. macrurus have started to shed light on the role that transcriptional and post-transcriptional events play in regulating specific muscle protein systems and the muscle phenotype of the EO. In addition, these findings also represent an important step toward identifying mechanisms that affect the maintenance and plasticity of the muscle cell phenotype for the evolution of highly specialized non-contractile tissues.Key words: electrocyte, muscle-derived cells, muscle regulatory factors, post-transcriptional regulation. (Arnold and Braun, 1996; Buckingham, 1992;Olson, 1990;Pownall et al., 2002;Weintraub et al., 1991). MRFs have been described as 'master' regulators of the muscle phenotype because of their potential to turn on the myogenic program following their forced expression in a variety of non-muscle cell types (Braun et al., 1989; Braun et al., 1990; Choi et al., 1990; Davis et al., 1987; Edmondson and Olson, 1989;Hopwood and Gurdon, 1990;Hopwood et al., 1991;Ishibashi et al., 2005;Kocaefe et al., 2005;Miner and Wold, 1990;Rhodes and Konieczny, 1989;Santerre et al., 1993;Weintraub et al., 1989;Weintraub et al., 1991). Gene knockout animals further demonstrate that MRFs are important for skeletal muscle development (Braun et al., 1992; Braun et al., 1994;Hasty et al., 1993;Nabeshima et al., 1993;Rudnicki et al., 1992;Rudnicki et al., 1993;Venuti et al., 1995). These genetic studies support the broadly accepted idea that expression of MRFs is essential for a cell to fully activate the skeletal muscle program. However, other studies have shown that expression of MRFs alone is not enough to fully establish the myogenic program. For one, myogenic conversion of cells in culture requires permissive conditions such as the absence of growth factors (Braun et al., 1989; Brune...

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The developmental morphology of Torpedo marmorata: Electric organ—electrogenic phase

Cited by 61 publications

References 28 publications

Morphological, physiological and biochemical observations on skate electric organ

Morphological, physiological and biochemical observations on skate electric organ

Production and characterization of a monoclonal antibody directed against the 43,000-dalton v1 polypeptide from Torpedo marmorata electric organ.

Mechanisms of muscle gene regulation in the electric organ ofSternopygus macrurus

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