A vertebrate physiologist and expert in marine mammals, Baylor assistant professor of biology Dr. Stephen Trumble has made his fair share of national research headlines since he began working at Baylor in 2008. Along with his graduate students in his Laboratory of Ecological and Adaptational Physiology (LEAP), Dr. Trumble investigates and publishes on basic and applied research involving skeletal muscle physiology, organismal energetics, lipid biochemistry, digestive physiology and health indices in models ranging from rats to seals to whales.
Dr. Trumble along with Baylor environmental science professor Dr. Sascha Usenko have developed a novel approach in determining lifespan hormonal and contaminant profiles for individual baleen whales using the wax earplug. These unprecedented lifespan profiles will fundamentally transform the ability to assess anthropogenic impact on these charismatic sentinels and their ecosystems.
Trumble graduated from Texas State University with a degree in marine biology. He has since received a M.S. and Ph.D. in the same field from Moss Landing Marine Labs and University of Alaska Fairbanks, respectively.
Industry Expertise (2)
Areas of Expertise (7)
University of Alaska Fairbanks: Ph.D., Marine Biology 2003
CSUF-Moss Landing Marine Labs: M.S., Marine Science 1995
Texas State University (SWTSU): B.S., Marine Biology 1988
Media Appearances (2)
For Scientists, Chunks of Whale Earwax Can Be Biological Treasure Troves
Smithsonian Magazine online
Whale earwax? Really? It’s weird on so many levels—that whales even have earwax, that someone thought to go looking for something like that, and that the Smithsonian’s National Museum of Natural History has stored not one, not ten, but about 1,000 samples of whale earwax plugs for well over 50 years.
Baylor Professors Use Whale Earwax to Develop New Method of Determining Lifetime Contaminant Exposure in Whales
Baylor Media Communications online
Baylor University professors Stephen Trumble, Ph.D., and Sascha Usenko, Ph.D., have developed a novel technique for reconstructing contaminant and hormone profiles using whale earplugs, determining--for the first time--lifetime chemical exposures and hormone profiles--from birth to death--for an individual whale, information that was previously unattainable.
As marine divers, pinnipeds have a high capacity for exercise at depth while holding their breath. With finite access to oxygen, these species need to be capable of extended aerobic exercise and conservation of energy. Pinnipeds must deal with common physiological hurdles, such as hypoxia, exhaustion and acidosis, that are common to all exercising mammals. The physiological mechanisms in marine mammals used for managing oxygen and carbon dioxide have sparked much research, but access to animals and tissues is difficult and requires permits. Deceased animals that are either bycaught or stranded provide one potential source for tissues, but the validity of biochemical data from post-mortem samples has not been rigorously assessed. Tissues collected from stranded diving mammals may be a crucial source to add to our limited knowledge on the physiology of some of these animals and important to the conservation and management of these species. We aim to determine the reliability of biochemical assays derived from post-mortem tissue and to promote the immediate sampling of stranded animals for the purpose of physiological research. In this study, we mapped the temporal degradation of muscle enzymes from biopsied Northern elephant seals ( Mirounga angustirostris ) and highlight recommendations for storage protocols for the best preservation of tissue. We also compared the enzymatic activity of different muscle groups (pectoral and latissimus dorsi) in relation to locomotion and measured the effects of four freeze–thaw cycles on muscle tissue enzyme function. Results indicate that enzymatic activity fluctuates greatly, especially with varying storage temperature, storage time, species and muscle group being assayed. In contrast, proteins, such as myoglobin, remain relatively continuous in their increase at 4°C for 48 h. Stranded animals can be a valuable source of biochemical data, but enzyme assays should be used only with great caution in post-mortem tissues.
Myoglobin (Mb) is an oxygen-binding muscular hemeprotein regulated via Ca2+-signaling pathways involving calcineurin (CN), with Mb increases attributed to hypoxia, exercise, and nitric oxide. Here, we show a link between lipid supplementation and increased Mb in skeletal muscle. C2C12 cells were cultured in normoxia or hypoxia with glucose or 5% lipid. Mb assays revealed that lipid cohorts had higher Mb than control cohorts in both normoxia and hypoxia, whereas Mb Western blots showed lipid cohorts having higher Mb than control cohorts exclusively under hypoxia. Normoxic cells were compared with soleus tissue from normoxic rats fed high-fat diets; whereas tissue sample cohorts showed no difference in CO-binding Mb, fat-fed rats showed increases in total Mb protein (similar to hypoxic cells), suggesting increases in modified Mb. Moreover, Mb increases did not parallel CN increases but did, however, parallel oxidative stress marker augmentation. Addition of antioxidant prevented Mb increases in lipid-supplemented normoxic cells and mitigated Mb increases in lipid-supplemented hypoxic cells, suggesting a pathway for Mb regulation through redox signaling independent of CN.
In 1940, Scholander suggested that stiffened upper airways remained open and received air from highly compressible alveoli during marine mammal diving. There are few 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.
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.
Currently, obtaining lifetime chemical profiles (i.e., from birth to death) is extremely rare and difficult for most of Earth’s animals. We have developed a unique approach to quantify hormone and contaminant lifetime profiles for an individual blue whale with a 6-mo resolution using the wax earplug as a natural matrix capable of archiving and preserving these temporal profiles. Using a male blue whale earplug, chemical analysis reveals lifetime patterns of mercury and organic pollutant exposure as well as fluctuating hormone levels. Specifically, we quantified contaminant maternal transfer, time to sexual maturity, and the doubling of stress over the animal’s lifespan. We anticipate that this technique will fundamentally transform our ability to assess human impact on these environmental sentinels and their ecosystems.