RESUMEN
This report reviews the academic lineage of Sir John Eccles; who trained him, whom he then trained and with whom he collaborated, and the subsequent impact of his trainees and collaborators on neuroscience and other areas. In a post-training career at five institutions in four countries (Great Britain, Australia, New Zealand, back to Australia, USA) and during retirement in Switzerland, Eccles trained and collaborated with over 180 people (mostly neuroscientists) from 21 countries. Most of them have had stellar research and training records that span the cellular-behavioral-philosophical spectrum of neuroscience, with a focus from peripheral neuromuscular issues to the forebrain. Some have been equally distinguished in other areas of biomedical science. Eccles' academic contributions and lineage are a valuable colloquium topic in a neuroscience training program. His experimental work spanned much of the 20th C before the recent emphasis on the application of the techniques of molecular biology. He continually sought to integrate information from the cellular to the systems and behavioral levels of analysis and synthesis. He also devoted a substantial amount of his intellectual effort to the mind-brain and other philosophical issues. Eccles' prodigious working hours and enthusiasm for his projects were a role model for such trainees. Hard-working trainees often ask how can they retain their all-round interests, and indeed their humanity and citizenry, as they focus more and more on their necessarily narrowly focused neuroscience research. Again, Eccles' writings and overall behavior show that it can indeed be done, but only by the application of extraordinary effort and dedication.
Asunto(s)
Centros Médicos Académicos/historia , Neurociencias/educación , Neurociencias/historia , Enseñanza/historia , Encéfalo/fisiología , Historia del Siglo XX , Intercambio Educacional Internacional/historia , Neurofisiología/educación , Neurofisiología/historia , Premio NobelRESUMEN
A description is provided of the ratio of slow-tonic vs. slow- and fast-twitch fibers for five muscles in the adult turtle, Pseudemys (Trachemys) scripta elegans. The cross-sectional area of each fiber type and an estimation of the relative (weighted) cross-sectional area occupied by the different fiber types are also provided. Two hindlimb muscles (flexor digitorum longus, FDL; external gastrocnemius, EG) were selected on the basis of their suitability for future motor-unit studies. Three neck muscles (the fourth head of testo-cervicis, TeC4; the fourth head of retrahens capitus collique, RCCQ4; transversalis cervicis, TrC) were chosen for their progressively decreasing oxidative capacity. Serial sections were stained for myosin adenosine triphosphatase (ATPase), NADH-diaphorase, and alpha-glycerophosphate dehydrogenase (alpha-GPDH). Conventional fiber-type classification was then performed using indirect markers for contraction speed and oxidative (aerobic) vs. glycolytic (anaerobic) metabolism: i.e., slow oxidative (SO, including slow-twitch and possibly slow-tonic fibers), fast-twitch, oxidative-glycolytic (FOG), and fast-twitch glycolytic (Fg) fibers. Slow-tonic fibers in the SO class were then revealed by directing the monoclonal antibody, ALD-58 (raised against the slow-tonic fiber myosin heavy chain of chicken anterior latissimus dorsi), to additional muscle cross sections. All five of the tested muscles contained the four fiber types, with the ATPase-stained fibers including both slow-tonic and slow-twitch fibers. The extreme distributions of SO fibers were in the predominately glycolytic TrC vs. the predominately oxidative TeC4 muscle (TrC-SO, 9%; FOG, 20%; Fg, 71% vs. TeC4-SO, 58%: FOG, 16%; Fg, 25%). Across the five muscles, the relative prevalence of slow-tonic fibers (4-47%) paralleled that of the SO fibers (9-58%). TeC4 had the highest prevalence of slow-tonic fibers (47%). The test muscles exhibited varying degrees of regional concentration of each fiber type, with the distribution of slow-tonic fibers paralleling that of the SO fibers. In the five test muscles, fiber cross-sectional area was usually ranked Fg > FOG > SO, and slow-twitch always > slow-tonic. In terms of weighted cross-sectional area, which provides a coarse-grain measure of each fiber type's potential contribution to whole muscle force, all five muscles exhibited a higher Fg and lower SO contribution to cross-sectional area than suggested by their corresponding fiber-type prevalence. This was also the case for the slow-twitch vs. slow-tonic fibers. We conclude that slow-tonic fibers are widespread in turtle muscle. The weighted cross-sectional area evidence suggested, however, that their contribution to force generation is minor except in highly oxidative muscles, with a special functional role, like TeC4. There is discussion of: 1) the relationship between the present results and previous work on homologous neck and hindlimb muscles in other nonmammalian species, and 2) the potential motoneuronal innervation of slow-tonic fibers in turtle hindlimb muscles.