Testing extraction and storage parameters for a fecal hormone method

Four experiments were conducted to test different aspects of a “field-friendly” fecal hormone extraction method that utilizes methanol extraction in the field followed by storage on C18 solid-phase extraction cartridges. Fecal samples were collected from geladas ( Theropithecus gelada ) housed at the Bronx Zoo, and the experiments were conducted in a laboratory setting to ensure maximum control. The experiments were designed to either simulate the conditions to which fecal samples are subjected during fieldwork or improve on an existing protocol. The experiments tested the relationship between fecal hormone metabolite preservation/recovery and: (1) the amount of time a sample is stored at ambient temperature; (2) the number of freeze/thaw cycles a sample undergoes; (3) the effectiveness of different extraction solutions; and (4) the effectiveness of different cartridge washes. For each experiment, samples were assayed by radioimmunoassay for fecal glucocorticoid (GC) and testosterone (T) metabolites. Results for each of the experiments were as follows. First, storage at ambient temperature did not affect hormone levels until 4 weeks of storage, with significant increases for both GC and T metabolites at 4 weeks. Second, hormone levels significantly decreased in samples after two freeze/thaw cycles for GCs and six freeze/thaws cycles for T. Third, for both GCs and T, hormone extraction using various methanol solutions was significantly higher than using 100% ethanol. Finally, using a 20% methanol solution to wash cartridges significantly increased GC levels but had no effect on T levels. These results suggest that, when utilizing C18 cartridges for fecal steroid storage, researchers should consider several methodological options to optimize hormone preservation and recovery from fecal samples. Am. J. Primatol. 72:934–941, 2010. © 2010 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78062/1/20859_ftp.pd

Endocrine Disrupting Chemicals and Conservation of Terrestrial Mammals

As evidence of the threat of endocrine disrupting chemicals (EDCs) is mounting, there is a need to revise our research efforts. EDCs present a novel challenge to the evolved endocrine processes of both humans and wildlife species. Biases in past research allowed for the formation of gaps in out knowledge concerning the identity and effects of EDCs. In order to correct these biases we must employ experimental models and explore a wider range of contaminants, species, effects, and exposure regimes. Here I present an example of a well-understood experimental model that fulfills the deficiencies left by the biases: sheep. A series of experiments conducted in both female and male sheep demonstrate that exposure to steroid hormones during development can alter behavior without causing any noticeable external effects. These alterations to behavior decreased reproductive fitness compared to controls, illustrating the need for the inclusion of behavior in surveys for EDC detection. This, and other experimental models, will begin to help us explore the full range of EDC effects in both humans and wildlife species.Master of ScienceSchool of Natural Resources and EnvironmentUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/50492/1/EKR Thesis 04172007.do