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The role of tropomyosin during heart development (Part I) and neuroanatomical and cardiorespiratory changes associated with metamorphosis (Part II) in the axolotl, Ambystoma mexicanum

Narshi, Aruna (2011)
Ph.D. thesis, University of Birmingham.

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I: Ambystoma mexicanum is a useful model for the study of heart development as it has a naturally occurring mutant, the cardiac (c/c) lethal, in which the embryos lack organised myofibrils and have low levels of tropomyosin. Antisense oligonucleotides specific to axolotl tropomyosin disrupted myofibril formation in normal heart, whereas sense oligonucleotides encouraged myofibrillogenesis in the mutant hearts, demonstrating the importance of tropomyosin in cardiac muscle development and the effectiveness of cationic liposome transfection system. A novel isoform of the human tropomyosin, TPM1κ, was discovered and found to be cardiac specific in humans. Ectopic expression of GFP.TPM1κ fusion protein promoted myofibrillogenesis in the cardiac mutant axolotl heart. Tropomyosin N- and C-termini modification did not affect its function.

II: The neotenous form had vagal preganglionic neurons (VPN) in the dorsal vagal nucleus (DVN) only. In the metamorphosed, VPN were found in the DVN but 18% were relocated in a ventro-lateral position. Neotenous ventilation rate followed heart rate. In the metamorphosed, ventilation caused heart rate variability. This may have been induced by the ventral-lateral VPN, which may be equivalent to a primitive nucleus ambiguus, an area that generates rhythmic sinus arrhythmia in mammals. Thus, ventrolateral VPN may be involved in cardiorespiratory control.

Type of Work:Ph.D. thesis.
Supervisor(s):Taylor, Edward W.
School/Faculty:Colleges (2008 onwards) > College of Life & Environmental Sciences
Department:School of Biosciences
Subjects:QH301 Biology
RC Internal medicine
Institution:University of Birmingham
ID Code:2977
This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder.
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