Moore Colby D.

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Colby D.

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  • Preprint
    Static inflation and deflation pressure–volume curves from excised lungs of marine mammals
    ( 2011-06-28) Fahlman, Andreas ; Loring, Stephen H. ; Ferrigno, Massimo ; Moore, Colby D. ; Early, Greg A. ; Niemeyer, Misty E. ; Lentell, Betty J. ; Wenzel, Frederick W. ; Joy, Ruth ; Moore, Michael J.
    Excised lungs from 8 marine mammal species (harp [Pagophilus groenlandicus], harbor [Phoca vitulina], and gray seal [Halichoerus grypus], Atlantic white-sided [Lagenorhynchus acutus], common [Delphinus delphis] and Risso's dolphin [Grampus griseus], long finned pilot whale [Globicephala melas], and harbor porpoise [Phocoena phocoena]) were used to determine minimum air volume of the relaxed lung (MAV, n = 15) and the elastic properties (pressure-volume curves, n = 24) of the respiratory system, and total lung capacity (TLC). Our data indicate that mass-specific TLC (sTLC, l • kg-1) does not differ between species or groups (odontocete vs. phocid) and agree with that estimated (TLCest) from body mass (Mb) by: TLCest = 0.135 • Mb 0.92. Measured MAV was on average 7% of TLC, with a range from 0% to 16%. The pressure-volume curves were similar among species on inflation but diverged during deflation in phocids as compared with odontocetes. These differences provide a structural basis for observed species differences in depth at which lungs collapse and gas exchange ceases.
  • Article
    Ontogenetic changes in skeletal muscle fiber type, fiber diameter and myoglobin concentration in the Northern elephant seal (Mirounga angustirostris)
    (Frontiers Media, 2014-06-10) Moore, Colby D. ; Crocker, Daniel E. ; Fahlman, Andreas ; Moore, Michael J. ; Willoughby, Darryn S. ; Robbins, Kathleen A. ; Kanatous, Shane B. ; Trumble, Stephen J.
    Northern elephant seals (Mirounga angustirostris) (NES) are known to be deep, long-duration divers and to sustain long-repeated patterns of breath-hold, or apnea. Some phocid dives remain within the bounds of aerobic metabolism, accompanied by physiological responses inducing lung compression, bradycardia, and peripheral vasoconstriction. Current data suggest an absence of type IIb fibers in pinniped locomotory musculature. To date, no fiber type data exist for NES, a consummate deep diver. In this study, NES were biopsied in the wild. Ontogenetic changes in skeletal muscle were revealed through succinate dehydrogenase (SDH) based fiber typing. Results indicated a predominance of uniformly shaped, large type I fibers and elevated myoglobin (Mb) concentrations in the longissimus dorsi (LD) muscle of adults. No type II muscle fibers were detected in any adult sampled. This was in contrast to the juvenile animals that demonstrated type II myosin in Western Blot analysis, indicative of an ontogenetic change in skeletal muscle with maturation. These data support previous hypotheses that the absence of type II fibers indicates reliance on aerobic metabolism during dives, as well as a depressed metabolic rate and low energy locomotion. We also suggest that the lack of type IIb fibers (adults) may provide a protection against ischemia reperfusion (IR) injury in vasoconstricted peripheral skeletal muscle.
  • Preprint
    A comparative analysis of marine mammal tracheas
    ( 2013-11) Moore, Colby D. ; Moore, Michael J. ; Trumble, Stephen J. ; Niemeyer, Misty E. ; Lentell, Betty J. ; McLellan, William A. ; Costidis, Alexander M. ; Fahlman, Andreas
    In 1940, Scholander suggested that stiffened upper airways remained open and received air from highly compressible alveoli during marine mammal diving. There are little data available on the structural and functional adaptations of the marine mammal respiratory system. The aim of this research was to investigate the anatomical (gross) and structural (compliance) characteristics of excised marine mammal tracheas. Here we defined different types of tracheal structures, categorizing pinniped tracheas by varying degrees of continuity of cartilage (categories 1-4) and cetacean tracheas by varying compliance values (categories 5A and 5B). Some tracheas fell into more than one category, along their length, for example, the harbor seal (Phoca vitulina) demonstrated complete rings cranially, and as the trachea progressed caudally tracheal rings changed morphology. Dolphins and porpoises had less stiff, more compliant spiraling rings while beaked whales had very stiff, less compliant spiraling rings. The pressure-volume (P-V) relationships of isolated tracheas from different species were measured to assess structural differences between species. These findings lend evidence for pressure-induced collapse and re-inflation of lungs, perhaps influencing variability in dive depth or ventilation rates of the species investigated.