Living on the edge: thermophysiology of the southern flying squirrel at its northern range margin

Climate change has the potential to upset entire ecological systems, making predictive models of the utmost importance. The incorporation of physiological parameters into predictive models not only bolsters their accuracy but also provides a mechanistic explanation for ecological changes already observed and those yet to come. North American flying squirrels, for example, have already experienced dramatic range shifts northward over recent decades, with climate change being the suspected driver. While other studies have focused on warming winter temperatures, I explored the hypothesis that rising summer temperatures were driving the observed range shifts. Unable to find a reliable population of the northern species, Glaucomys sabrinus, I focused on southern flying squirrels, Glaucomys volans, to determine the effect of high temperatures on thermoregulation and energy usage. Using flow-through respirometry, I measured the relationship between temperature and metabolic rate/evaporative water loss/body temperature. I used temperature-sensitive data loggers to measure core body temperature in free-ranging flying squirrels to explore an additional thermoregulatory strategy – heterothermy. I discovered no significant increase in metabolic rate in temperatures up to 40°C but did detect an increase in evaporative water loss starting at 36.2°C. Body temperature (Tb) of flying squirrels followed a circadian pattern with ~2°C difference between active and resting phase modal Tb. This daily level of heterothermy is consist with, but slightly higher, than other squirrel species according to the Heterothermy Index. High temperatures are unlikely to cause an energetic strain on southern flying squirrels in Maine as long as water resources remain available. Measurements of microclimate, accounting for group nesting and cavity insulation, are still needed to fully understand the extent of heterothermy and the influence of high ambient temperature on the thermoregulation of G. volans in Maine

THE PRAIRIE NATURALIST Volume 23, No. 1. March 1991

Paul B. Kannowski, Editor Nikki R. Seabloom, Assistant Editor Douglas H. Johnson, Book Review Editor CONTENTS AGRICULTURAL LAND USE AND MOURNING DOVES IN EASTERN COLORADO: IMPLICATIONS FOR NESTING AND PRODUCTION IN THE GREAT PLAINS ▪ T E. Olson, C. E. Braun, and R. A. Ryder DISTRIBUTION OF SANDHILL CRANES IN THE NORTH PLATTE RIVER VALLEY 1980 AND 1989 ▪ M. J. Folk and T. C. Tacha NOCTURNAL BEHAVIOR OF SANDHILL CRANES ROOSTING IN THE PLATTE RIVER, NEBRASKA ▪ B. S. Norling, S. H. Anderson, and W A. Hubert LEAD POISONING OF A MARBLED GODWIT ▪ L. N. Locke, M. R. Smith, R. M. Windingstad, and S. J. Martin GEOGRAPHIC AFFINITY OF BIRD SPECIES ASSOCIATED WITH ROCKY MOUNTAIN JUNIPER WOODLANDS AND ADJACENT GRASSLANDS IN SOUTHWESTERN SOUTH DAKOTA ▪ C. H. Sieg IMPLANTING RADIO TRANSMITTERS IN PLAINS POCKET GOPHERS ▪ K. C. Zinnel and J. R. Tester COURTSHIP, EGGS, AND DEVELOPMENT OF THE PLAINS TOPMINNOW IN NEBRASKA (ACTINOPTERYGII: FUNDULIDAE) ▪ S. A. Kaufmann and J. D. Lynch BOOK REVIEWS Nature Television in a Book ▪ N. L. Ford A Natural History Imperative ▪ B. Heidel NOTE Two Incubating Mallards Move Eggs to Drier Nest Sites ▪ J. P. Fleskes EDITORIAL POLICY ▪ Editor SUGGESTIONS FOR CONTRIBUTORS ▪ Editor Mailing Date: April 26, 199

The Effects of Rising Ambient Temperatures on Thermoregulation and Range Shifts of Northern Flying Squirrels

Climate change may potentially alter a species’ range distribution and thus the relationship between environmental temperatures and animal performance as a response to climate warming has become an important area of research. Two species of flying squirrel in North America, the southern flying squirrel (Glaucomys volans) and the northern flying squirrel (Glaucomys sabrinus) have undergone northward range shifts, with climate warming being the suspected driver. Because they are nocturnal and tree nesting, flying squirrels may be particularly susceptible to warmer temperatures, as they will experience the highest daily ambient temperatures during their resting phase. I used G. sabrinus as a study species to determine the effect of high temperatures on thermoregulation and energy use to test if thermal limits will contribute to range shifts. I measured metabolic rate and evaporative water loss under different ambient temperatures using flow-through respirometry and estimated the responses to high ambient temperatures in the field by measuring body temperature. I used climate data from Arrowsic, Bangor, and Presque Isle, Maine over recent decades to determine if temperature increases would correspond to the northward movement of flying squirrels in Maine. G. sabrinus did not show visible or physiological signs of heat stress during respirometry experiments, and an upper critical temperature was not reached at temperatures tested. Consistent daily rhythms in body temperature were observed in free-ranging flying squirrels, as predicted, and increased as ambient temperatures decreased. Additionally, high ambient temperatures were not likely to be a direct factor in northern flying squirrel range shifts, but that climate warming caused G. volans to move north and outcompete G. sabrinus

Volumetric Manganese Enhanced Magnetic Resonance Imaging in mice (mus musculus)

The present doctoral thesis introduces a method for semi-automatic volumetric analysis of the hippocampus and other distinct brain regions in laboratory mice. The method of volumetric manganese enhanced magnetic resonance imaging (vMEMRI) makes use of the paramagnetic property of the manganese ion, Mn2+, which results in a positive contrast enhancement of specific brain areas on the MR image and enables a more detailed image of brain morphology. The chemical similarity of Mn2+ to Calcium leads to an accumulation of Mn2+ in excited cells and consequentially an enhanced signal in certain brain regions in an activity dependent manner. However, one major drawback for vMEMRI is the toxicity of Mn2+. Therefore, the aims of the thesis have been: (1) Establishment of a MEMRI protocol in mice (2) Optimization of a Mn2+ application procedure to reduce toxic side effects (3) Development of an automatized method to determine hippocampal volume (4) Validation of vMEMRI analysis (5) Application of volumetric analysis in mouse models of psychopathology This thesis splits into 3 studies. Study 1 deals with Mn2+ toxicity and introduces an application method that considerably reduces the toxic side effects of Mn2+. Study 2 validates vMEMRI as a method to reliably determine hippocampal volume and explores its utilization it in animals with genetically and chemically modified hippocampi. Study 3 displays the application vMEMRI in a mouse model of a psychiatric disorder. Study 1 shows that a single application of Mn2+ in dosages used in current MEMRI studies leads to considerable toxic side effects measurable with physiological, behavioral and endocrine markers. In contrast, a fractionated application of a low dose of Mn2+ is proposed as an alternative to a single injection of a high dose. Repeated application of low dosages of 30 mg/kg Mn2+ showed less toxic side effects compared to the application schemes with higher dosages of 60 mg/kg. Additionally, the best vMEMRI signal contrast was seen for an injection protocol of 30 mg/kg 8 times with an inter-injection interval of 24 h (8x30/24 protocol). The impact of the 8x30/24 application protocol on longitudinal studies was tested by determining whether learning processes are disturbed. Mice were injected with the 8x30/24 protocol 2 weeks prior to receiving a single footshock. Manganese injected mice showed less contextual freezing to the shock context and a shock context reminder one month after shock application. Furthermore, mice showed increased hyperarousal and no avoidance of shock context related odors. This impairment in fear conditioning indicates a disturbed associative learning of Mn2+ injected mice. Therefore, it was investigated whether Mn2+ application shows a specific disturbance of hippocampus dependent learning. Mice were subjected to habitual and spatial learning protocols 12 h after each injection in a water cross-maze. There was no impairment in learning protocols which allowed for hippocampus-independent habitual learning. However, Mn2+ injected mice were specifically impaired in the hippocampus-dependent spatial learning protocol. Furthermore, it was shown that only mice with higher Mn2+ accumulation showed this impairment. Altogether, the results of this chapter argue for a fractionated application scheme such as 30 mg/kg every 24 h for 8 days to provide sufficient MEMRI signal contrast while minimizing toxic side effects. However, the treatment procedure has to be further improved to allow for an analysis of hippocampus-dependent learning processes as well. Because of the potential side effects, the vMEMRI method was applied as a final experiment in study 2 and 3. Study 2 introduces the method of vMEMRI, which allows, for the first time, an in vivo semi-automatic detection of hippocampal volume. Hippocampal volume of mice with genetically altered adult neurogenesis and those with chemically lesioned hippocampi could be analyzed with vMEMRI. Even the highly variable differences in hippocampal volume of these animals could be detected with vMEMRI. vMEMRI data correlated with manually obtained volumes and are in agreement with previously reported histological findings, indicating the high reliability of this method. Study 3 investigates the ability of vMEMRI to detect even small differences in brain morphology by examining volumetric changes of the hippocampus and other brain structures in a mouse model of PTSD supplemented with enriched housing conditions. It was shown, that exposure to a brief inescapable foot shock led to a volume reduction in both the left hippocampus and right central amygdala two months later. Enriched housing decreased the intensity of trauma-associated contextual fear independently of whether it was provided before or after the shock. vMEMRI analysis revealed that enriched housing led to an increase in whole brain volume, including the lateral ventricles and the hippocampus. Furthermore, the enhancement of hippocampal volume through enriched housing was accompanied by the amelioration of trauma-associated PTSD-like symptoms. Hippocampal volume gain and loss was mirrored by ex vivo ultramicroscopic measurements of the hippocampus. Together, these data demonstrate that vMEMRI is able to detect small changes in hippocampal and central amygdalar volumes induced by a traumatic experience in mice. In conclusion, vMEMRI proves to be very reliable and able to detect small volumetric differences in various brain regions in living mice. vMEMRI opens up a great number possibilities for future research determining neuroanatomical structure, volumes and activity in vivo as well as the ability to repeatedly determine such characteristics within each subject, given an improvement of the Mn2+ treatment protocols to minimize potential toxic side effects

Southwest Research Institute assistance to NASA in biomedical areas of the technology utilization program Final report, 1 Feb. 1969 - 24 Aug. 1970

Research progress in technology transfer by NASA Biomedical Application Tea

The use of Keratin in biomedical applications

Keratins are naturally derived proteins that can be fabricated into several biomaterials morphologies including films, sponges and hydrogels. As a physical matrix, keratin biomaterials have several advantages of both natural and synthetic materials that are useful in tissue engineering and controlled released applications. Like other naturally derived protein biomaterials, such as collagen, keratin possess amino acid sequences, similar to the ones found on extracellular matrix (ECM), that may interact with integrins showing their ability to support cellular attachment, proliferation and migration. The ability of developing biomaterials that mimic ECM has the potential to control several biological processes and this is the case for keratin which has been used in a variety of biomedical applications due to its biocompatibility and biodegradability. This review describes the progress to date towards the use of keratin in the field of wound healing, tissue engineering and drug delivery applications, with highlight to reports of particular relevance to the development of the underlying biomaterials science in this area