Two novel/ancient myosins in mammalian skeletal muscles: MYH14/7b and MYH15 are expressed in extraocular muscles and muscle spindles

The mammalian genome contains three ancient sarcomeric myosin heavy chain (MYH) genes, MYH14/7b, MYH15 and MYH16, in addition to the two well characterized clusters of skeletal and cardiac MYHs. MYH16 is expressed in jaw muscles of carnivores; however the expression pattern of MYH14 and MYH15 is not known. MYH14 and MYH15 orthologues are present in frogs and birds, coding for chicken slow myosin 2 and ventricular MYH, respectively, whereas only MYH14 orthologues have been detected in fish. In all species the MYH14 gene contains a microRNA, miR-499. Here we report that in rat and mouse, MYH14 and miR-499 transcripts are detected in heart, slow muscles and extraocular (EO) muscles, whereas MYH15 transcripts are detected exclusively in EO muscles. However, MYH14 protein is detected only in a minor fibre population in EO muscles, corresponding to slow-tonic fibres, and in bag fibres of muscle spindles. MYH15 protein is present in most fibres of the orbital layer of EO muscles and in the extracapsular region of bag fibres. During development, MYH14 is expressed at low levels in skeletal muscles, heart and all EO muscle fibres but disappears from most fibres, except the slow-tonic fibres, after birth. In contrast, MYH15 is absent in embryonic and fetal muscles and is first detected after birth in the orbital layer of EO muscles. The identification of the expression pattern of MYH14 and MYH15 brings to completion the inventory of the MYH isoforms involved in sarcomeric architecture of skeletal muscles and provides an unambiguous molecular basis to study the contractile properties of slow-tonic fibres in mammals

SPORT & EXERCISE PSYCHOLOGY PROFESSIONAL DOCTORATE PORTFOLIO

This portfolio demonstrates my personal and professional development as a trainee sport and exercise psychologist during the Professional Doctorate in Sport and Exercise Psychology at Liverpool John Moores University. The portfolio provides evidence of how I meet the competencies (professional standards, consultancy, research, teaching, and dissemination) of the British Psychological Society (BPS) and Health and Care Professions Council (HCPC) for ‘Chartered’ and ‘Practitioner’ Psychologists. The selected reading highlights literature that was influential to my personal and professional development. The practice log demonstrates the hours I spent on each learning outcome. The reflective diary highlights my learning experiences and critical moments central to the development of my personal philosophy, approach to practice, and personal development. Four applied case studies are presented. These provide accounts of my approach to service delivery in applied work, teaching, and dissemination. The case studies demonstrate work across different settings: with youth academy football coaches, an injured ballet dancer, a ballet dancer experiencing an eating disorder and ethical challenges within a ballet academy, and a psychology support program in a professional dance college. The scoping review examined resilience in elite sport. A common thread of the empirical papers is elite youth academy football. The first empirical paper explores practitioner’s design and delivery of an existential psychology program. The second empirical paper explores Team Formulation. The reflective commentary brings together my training which includes what I have learned, how I developed competencies, and how it has contributed to the development of a coherent and congruent approach to practice

Expression of type-specific MHC isoforms in rat intrafusal muscle fibers.

Myosin heavy chain (MHC) expression by intrafusal fibers was studied by immunocytochemistry to determine how closely it parallels MHC expression by extrafusal fibers in the soleus and tibialis anterior muscles of the rat. Among the MHC isoforms expressed in extrafusal fibers, only the slow-twitch MHC of Type 1 extrafusal fibers was expressed along much of the fibers. Monoclonal antibodies (MAb) specific for this MHC bound to the entire length of bag2 fibers and the extracapsular region of bag1 fibers. The fast-twitch MHC isoform strongly expressed by bag2 and chain fibers had an epitope not recognized by MAb to the MHC isoforms characteristic of developing muscle fibers or the three subtypes (2A, 2B, 2X) of Type 2 extrafusal fibers. Therefore, intrafusal fibers may express a fast-twitch MHC that is not expressed by extrafusal fibers. Unlike extrafusal fibers, all three intrafusal fiber types bound MAb generated against mammalian heart and chicken limb muscles. The similarity of the fast-twitch MHC of bag2 and chain fibers and the slow-tonic MHC of bag1 and bag2 fibers to the MHC isoforms expressed in avian extrafusal fibers suggests that phylogenetically primitive MHCs might persist in intrafusal fibers. Data are discussed relative to the origin and regional regulation of MHC isoforms in intrafusal and extrafusal fibers of rat hindlimb muscles

Development of fusimotor innervation correlates with group Ia afferents but is independent of neurotrophin-3

Fusimotor neurons, group Ia afferents and muscle spindles are absent in mutant mice lacking the gene for neurotrophin-3 (NT3). To partition the effect of Ia afferent or spindle absence from that of NT3 deprivation on fusimotor neuron development, we examined the fusimotor system in a mutant mouse (NesPIXpNT3) that lacks Ia afferents and spindles, but has normal or elevated tissue levels of NT3 during embryogenesis. Fusimotor fibers were absent in lumbar ventral spinal roots, and limb muscles were devoid of Ia afferents and spindles in adult NesPIXpNT3 mice. In contrast, no deficiency in motoneuron numbers was observed in the trigeminal nucleus which contains cell bodies of motor axons innervating muscles of mastication. Spindles and Ia afferents were also present in the masticatory muscles. Thus, the development and/or survival of fusimotor neurons correlates with the presence of Ia afferents and/or spindles, and not with the amount of NT3 in the spinal cord or muscle. (C) 1998 Elsevier Science B.V. All rights reserved