Construction and use of a direct calorimeter to estimate energy expenditure in hibernators

Metabolic rates have traditionally been estimated through indirect calorimetry (gas exchange or respirometry) due to its ease and availability. Oxygen consumption neglects the contributions of anaerobic metabolism, while direct calorimetry (heat production) estimates both anaerobic and aerobic metabolism. Walsberg and Hoffman (2005) report anaerobic metabolism may be more important to small rodents than was previously thought. During the non-steady state of mammalian hibernation, we hypothesize that anaerobic processes may play an even greater role in fueling metabolism. To address this question, we constructed a very sensitive calorimeter that utilizes the Seebeck effect from a thermoelectric element (Peltier device). We describe its construction, characterization and will use the device to estimate heat production in hibernators this winter. We will compare estimates of energy use from the direct calorimeter from simultaneously obtained respirometry data to provide the most complete picture of energy use during hibernation to date

Construction and use of a calorimeter to estimate the anaerobic contributions to metabolism

Metabolism is derived from the Greek word metabole which translates to change. Metabolism is the sum total of chemical reactions that take place in an organism. Some reactions are exothermic (heat-producing) whereas others are endothermic (heat-absorbing). By measuring heat production (calorimetry), one can estimate metabolic rate. Historically, such measurements of direct calorimetry were difficult. As a result, most studies utilize indirect calorimetry wherein oxygen consumption and/or carbon dioxide production are measured. One limitation to this approach is that anaerobic metabolism is ignored. No commercially-available calorimeter is available for whole animal metabolic studies. We hypothesized that small rodent hibernators may experience significant anaerobic metabolism. In order to empirically determine the relative contributions of anaerobic and aerobic metabolism to a hibernator’s overall energetic budget, we built our own calorimeter

THE TAXONOMIC STATUS OF THE WYOMING TOAD, BUFO BAXTERI PORTER

The population of toads in southeastern Wyoming named Bufo hemiophrys baxteri by Porter in 1968 is presumed to be extinct in nature, except perhaps for released, captive-bred specimens. It is sufficiently distinct in several respects, and sufficiently isolated geographically from its nearest rela- tive, B. h. hemiophrys, that it should be regarded as a distinct species, forming a superspecies group with B. hemiophrys

THE LECTOTYPE AND TYPE LOCALITY OF CANDOIA CARINATA (REPTILIA, SERPENTES)

The lectotype of Boa carinata Schneider, 1801, has been rediscovered and is now ZMFK35503, having been transferred in 1977 from the Göttingen Museum, its original location. Its typelocality has not been reported previously, but is indicated as “Amboina” on a label with the lectotype.The specimen is redescribed and fi gured, and conforms with expectations for material from the vicinityof the type locality. A brief history of Schneider and of the syntypes of Boa carinata, now Candoiacarinata, is reviewed

Ubiquitin dependent proteolysis in the frozen Wood Frog

Wood frogs (Rana sylvatica) freeze during the winter. One might presume that homeostatic processes like protein synthesis and degradation cease during freezing. However, few data are available. In collaboration with Dr. Ken Storey (Carelton University, Canada), we are investigating the primary mode of proteolysis in wood frogs representing different points of the freeze-thaw cycle

Effects of climate change on the viability of the Devils Hole Pupfish

Devils hole is an unusual, cavernous, aquifer-fed its ideal temperature range. spring in Death Valley National Park. It is the only home to a critically endangered species, Cyprinidon diabolis, a.k.a. The Devils Hole Pupfish. C. diabolis allows us a unique look at the impact of climate change on a species that has no gene flow and no possibility of escape from its current habitat. Climate change affects ectotherms (cold-blooded animals) tremendously since their body temperature is subject to changes in the temperature of their environment. In the case of C. diabolis, they are subject to high temperatures year round, around 33°C. The high temperatures cause an increase in oxygen needs for essential metabolic activity as well as an increase in energy needs. The limited energy and oxygen availability of Devils Hole means C. diabolis has to work harder to merely stay alive and has less energy to dedicate to reproduction. Most biologists will tell you that animals are adapted to thrive in their environment. But what happens when the environment changes quickly, the genes necessary for adaptation are unavailable in the population, and there is no chance for finding a new habitat? The answer is simple; the population declines rapidly until the stress or stresses they face are removed. In the case of C. diabolis, we are investigating just how much stress is being placed on this population by an increase in temperature. Recent climate change models predict a 5 – 6°C increase in average air temperatures across the southwest portion of the United States in the next 80 years (Meehl, et al., 2007). In biological systems, a 1° C change in body temperature may result in a \u3e10% higher energy demand. Although we do not know what the effects of higher air temperatures will be on Devils Hole water temperature, it is likely that even a modest change in temperature will result in greater energetic demand

Ubiquitylation of proteins in the frozen wood frog

Wood frogs (Rana sylvatica) are able to withstand freezing. Respiratory and cardiac activity ceases when frozen. Homeostatic functions like protein synthesis and degradation presumably must also be compromised. We investigated the fate of ubiquitin-dependent proteolysis in the freeze-thaw cycle and how that might gives clues to wood frog survival. We performed western blots for ubiquitin conjugate

Clustering of red galaxies around the z=1.53 quasar 3C270.1

In the paradigm of hierarchical galaxy formation, luminous radio galaxies mark mass assembly peaks that should contain clusters of galaxies. Observations of the z=1.53 quasar 3C270.1 with the Spitzer Space Telescope at 3.6-24 micron and with the 6.5-m MMT in the z'- and Y-bands allow detection of potential cluster members via photometric redshifts. Compared with nearby control fields, there is an excess of 11 extremely red objects (EROs) at 1.33 < z_phot < 1.73, consistent with a proto-cluster around the quasar. The spectral energy distributions (SEDs) of 3/4 of the EROs are better fitted with passive elliptical galaxies than withdust-reddened starbursts, and of four sources well-detected on an archival HST snapshot image, all have undisturbed morphologies. However, one ERO, not covered by the HST image, is a double source with 0.8" separation on the z' image and a marginal (2sigma) 24 micron detection indicating a dust-enshrouded starburst. The EROs are more luminous than L* (H = -23.6 AB mag at z=1.5).Comment: 12 pages, 7 figures, accepted by Ap