A non-invasive water-borne hormone assay for amphibians

Self Cite

Water‐borne hormone measurement is a noninvasive method suitable for amphibians of all sizes that are otherwise difficult to sample. For this method, containment‐water is assayed for hormones released by the animal. Originally developed in fish, the method has expanded to amphibians, but requires additional species‐specific validations. We wanted to determine physiological relevance of water‐borne corticosterone in spotted salamanders (Ambystoma maculatum) by comparing concentrations to those taken using established corticosterone sampling methods, such as plasma. Using a mixture of field and laboratory studies, we compared water‐borne corticosterone levels to other traditional methods of sampling corticosterone for spotted salamander larvae, metamorphs, and adults. Despite multiple attempts, and detecting differences between age groups, we found no correlations between water‐borne and plasma corticosterone levels in any age group. Water‐borne sampling measures a rate of release; whereas plasma is the concentration circulating in the blood. The unique units of measurement may inherently prevent correlations between the two. These two methods may also require different interpretations of the data and the physiological meaning. We also note caveats with the method, including how to account for differences in body size and life history stages. Collectively, our results illustrate the importance of careful validation of water‐borne hormone levels in each species in order to understand its physiological significance.

Section: Introductionmentioning

confidence: 99%

“…Water‐borne corticosterone is interpreted as a cumulative measure of the hormone over a set period of time, usually 1 hr (Gabor et al, ; Scott & Ellis, ). This reflects the corticosterone release rate, or the rate of secretion of the hormone (Dantzer, Fletcher, Boonstra, & Sheriff, ; Gabor et al, ; Scott & Ellis, ).…”

Section: Introductionmentioning

confidence: 99%

Water‐borne and plasma corticosterone are not correlated in spotted salamanders

Millikin

Woodley

Davis

et al. 2019

Self Cite

“…; Gabor et al. ). Briefly, the columns were primed with HPLC grade methanol and Millipore filtered water, then the 800 mL of diluted plasma was filtered through the columns under vacuum.…”

Section: Methodsmentioning

confidence: 98%

“…Both tissues were validated in these kits using pooled samples for serial dilutions and quantitative recovery (Earley and Hsu ; Gabor et al. ). For the feather CORT, the serial dilution curve was parallel to the standard curve (ANCOVA slope comparison; F 1,9 = 0.11, P = 0.75) and a dilution of 1:8 provided an optimal detection range.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Biomarkers of animal health: integrating nutritional ecology, endocrine ecophysiology, ecoimmunology, and geospatial ecology

Warne

Proudfoot

Crespi

2015

Diverse biomarkers including stable isotope, hormonal, and ecoimmunological assays are powerful tools to assess animal condition. However, an integrative approach is necessary to provide the context essential to understanding how biomarkers reveal animal health in varied ecological conditions. A barrier to such integration is a general lack of awareness of how shared extraction methods from across fields can provide material from the same animal tissues for diverse biomarker assays. In addition, the use of shared methods for extracting differing tissue fractions can also provide biomarkers for how animal health varies across time. Specifically, no study has explicitly illustrated the depth and breadth of spacial and temporal information that can be derived from coupled biomarker assessments on two easily collected tissues: blood and feathers or hair. This study used integrated measures of glucocorticoids, stable isotopes, and parasite loads in the feathers and blood of fall-migrating Northern saw-whet owls (Aegolius acadicus) to illustrate the wealth of knowledge about animal health and ecology across both time and space. In feathers, we assayed deuterium (δD) isotope and corticosterone (CORT) profiles, while in blood we measured CORT and blood parasite levels. We found that while earlier migrating owls had elevated CORT levels relative to later migrating birds, there was also a disassociation between plasma and feather CORT, and blood parasite loads. These results demonstrate how these tissues integrate time periods from weeks to seasons and reflect energetic demands during differing life stages. Taken together, these findings illustrate the potential for integrating diverse biomarkers to assess interactions between environmental factors and animal health across varied time periods without the necessity of continually recapturing and tracking individuals. Combining biomarkers from diverse research fields into an integrated framework hold great promise for advancing our understanding of environmental effects on animal health.

Physiological responses to a changing winter climate in an early spring‐breeding amphibian

Schmidt,

Zummach,

Sinai

et al. 2024

Climate change is swiftly altering environmental winter conditions, leading to significant ecological impacts such as phenological shifts in many species. As a result, animals might face physiological mismatches due to longer or earlier activity periods and are at risk of being exposed to late spring freezes. Our study points for the first time to the complex physiological challenges that amphibians face as a result of changing thermal conditions due to winter climate change. We investigated the physiological responses to a period of warmer winter days and sudden spring freeze in the common toad (Bufo bufo) by acclimating them to 4°C or 8°C for 48 h or exposing them to 4°C or −2°C for 6 h, respectively. We assessed the daily energy demands, determined body condition and cold tolerance, explored the molecular responses to freezing through hepatic tissue transcriptome analysis, and measured blood glucose levels. Toads acclimated to higher temperatures showed a higher daily energy expenditure and a reduced cold tolerance suggesting faster depletion of energy stores and the loss of winter acclimation during warmer winters. Blood sugar levels were higher in frozen toads indicating the mobilization of cryoprotective glucose with freezing which was further supported by changed patterns in proteins related to glucose metabolism. Overall, our results emphasize that increased thermal variability incurs physiological costs that may reduce energy reserves and thus affect amphibian health and survival. This might pose a serious threat to breeding adults and may have subsequent effects at the population level.