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Although physiological responses to the thermal environment are most frequently investigated using constant temperatures, the incorporation of thermal variability can allow for a more accurate prediction of how thermally sensitive species respond to a rapidly changing climate. In species with temperature-dependent sex determination (TSD), developmental responses to incubation temperature are mediated by several genes involved in gonadal differentiation. Kdm6b and Dmrt1 respond to cool incubation temperatures and are associated with testis development, while FoxL2 and Cyp19A1 respond to warm incubation temperatures and are associated with ovary development. Using fluctuating incubation temperatures, we designed two studies, one investigating how conflicting thermal cues affect the timing of commitment to gonadal development, and another investigating the rapid molecular responses to conflicting thermal cues in the red-eared slider turtle (Trachemys scripta). Using gene expression as a proxy of timing of commitment to gonadal fate, results from the first study show that exposure to high amounts of conflicting thermal cues during development delays commitment to gonadal fate. Results from the second study show that Kdm6b splice variants exhibit differential responses to early heat wave exposure, but rapidly (within 2 days) recover to pre-exposure levels after the heat wave. Despite changes in the expression of Kdm6b splice variants, there was no effect on Dmrt1 expression. Collectively, these findings demonstrate how short exposures to heat early in development can change how embryos respond to heat later in development.

Avalanches and other hazardous mass movements pose a danger to the population and critical infrastructure in alpine areas. Hence, understanding and continuously monitoring mass movements are crucial to mitigate their risk. We propose to use Distributed Acoustic Sensing (DAS) to measure strain rate along a fiber‐optic cable to characterize ground deformation induced by avalanches. We recorded 12 snow avalanches of various dimensions at the Vallée de la Sionne test site in Switzerland, utilizing existing fiber‐optic infrastructure and a DAS interrogation unit during the winter 2020/2021. By training a Bayesian Gaussian Mixture Model, we automatically characterize and classify avalanche‐induced ground deformations using physical properties extracted from the frequency‐wavenumber and frequency‐velocity domain of the DAS recordings. The resulting model can estimate the probability of avalanches in the DAS data and is able to differentiate between the avalanche‐generated seismic near‐field, the seismo‐acoustic far‐field, and the mass movement propagating on top of the fiber. By analyzing the mass‐movement propagation signals, we are able to identify group velocity packages within an avalanche that propagate faster than the phase velocity of the avalanche front, indicating complex internal structures. Importantly, we show that the seismo‐acoustic far‐field can be detected before the avalanche reaches the fiber‐optic array, highlighting DAS as a potential research and early warning tool for hazardous mass movements. Avalanches and other hazardous mass movements pose a danger to the population and critical infrastructure in alpine areas. Therefore, it is important to be able to reliably measure and detect these hazardous events. We show a successful example to measure and characterize avalanches recorded with a Distributed Acoustic Sensing device that measures deformation along a fiber optic cable. We apply unsupervised machine learning to our avalanche recordings and are able to identify consistent properties between 12 avalanches. Ultimately, our results indicate that DAS might be a useful tool for detecting hazardous mass movements. Distributed Acoustic Sensing measurements near the interface between avalanche and the subsurface reveal flow dynamicsStrain rate measurements of seismo‐acoustic waves are registered up to 30 s before avalanches reach the sensorsInternal group velocities larger than the propagation speed suggest the presence of complex internal structures Distributed Acoustic Sensing measurements near the interface between avalanche and the subsurface reveal flow dynamics Strain rate measurements of seismo‐acoustic waves are registered up to 30 s before avalanches reach the sensors Internal group velocities larger than the propagation speed suggest the presence of complex internal structures

Variation in developmental conditions can affect a variety of embryonic processes and shape a number of phenotypic characteristics that can affect offspring throughout their lives. This is particularly true of oviparous species where development typically occurs outside of the female, and studies have shown that traits such as survival and behavior can be altered by both temperature and exposure to steroid hormones during development. In species with temperature-dependent sex determination (TSD), the fate of gonadal development can be affected by temperature and by maternal estrogens present in the egg at oviposition, and there is evidence that these factors can affect gene expression patterns. Here, we explored how thermal fluctuations and exposure to an estrogen metabolite, estrone sulfate, affect the expression of several genes known to be involved in sexual differentiation: Kdm6b, Dmrt1, Sox9, FoxL2 and Cyp19A1. We found that most of the genes responded to both temperature and estrone sulfate exposure, but that the responses to these factors were not identical, in that estrone sulfate effects occur downstream of temperature effects. Our findings demonstrate that conjugated hormones such as estrone sulfate are capable of influencing temperature-dependent pathways to potentially alter how embryos respond to temperature, and highlight the importance of studying the interaction of maternal hormone and temperature effects.

The thermal environment that organisms experience can affect many aspects of their phenotype. As global temperatures become more unpredictable, it is imperative that we understand the molecular mechanisms by which organisms respond to variable, and often transient, thermal environments. Beyond deciphering the mechanisms through which organisms respond to temperature, we must also appreciate the underlying variation in temperature-dependent processes, as this variation is essential for understanding the potential to adapt to changing climates. In this Commentary, we use temperature-dependent sex determination as an example to explore the mechanistic processes underlying the development of temperature-sensitive phenotypes. We synthesize the current literature on how variable thermal conditions affect these processes and address factors that may limit or allow organisms to respond to variable environments. From these examples, we posit a framework for how the field might move forward in a more systematic way to address three key questions: (1) which genes directly respond to temperature-sensitive changes in protein function and which genes are downstream, indirect responders?; (2) how long does it take different proteins and genes to respond to temperature?; and (3) are the experimental temperature manipulations relevant to the climate the organism experiences or to predicted climate change scenarios? This approach combines mechanistic questions (questions 1 and 2) with ecologically relevant conditions (question 3), allowing us to explore how organisms respond to transient thermal environments and, thus, cope with climate change.

Maternal hormones can shape offspring development and increase survival when predation risk is elevated. In songbirds, yolk androgens influence offspring growth and begging behaviors, which can help mitigate offspring predation risk in the nest. Other steroids may also be important for responding to nest predation risk, but non-androgen steroids have been poorly studied. We used a nest predator playback experiment and liquid chromatography with tandem mass spectrometry (LC-MS-MS) to assess whether nest predation risk influences deposition of 10 yolk steroids. We found no clear evidence that yolk androgen deposition changed when perception of nest predation risk was experimentally increased. However, elevated nest predation risk led to decreased yolk progesterone deposition. Overall, our results suggest yolk progesterone may be more important than yolk androgens in responses to offspring predation risk and highlight new avenues for research.

In the painted turtle (Chrysemys picta) and red‐eared slider turtle (Trachemys scripta), the temperature that eggs are exposed to during incubation determines the sex of the developing embryo. Constant temperature incubation experiments have shown that for each of these species there is a pivotal temperature that produces a 1:1 sex ratio; higher temperatures bias sex ratios toward females, and lower temperatures toward males. Few studies have examined how fluctuating temperatures, as would be experienced in natural nests, affect hatchling phenotype. Models predict that under fluctuating temperatures sex determination depends on the proportion of development that occurs above or below the pivotal temperature. We tested the effect of fluctuating versus constant temperature incubation regimes on sex ratios and other hatchling traits for both painted and red‐eared slider turtles. Eggs were divided into two treatments with half of the eggs from each species incubated at a constant intermediate temperature, 28.5°C, and half incubated under temperatures that fluctuated 3°C above and below 28.5°C. We converted the fluctuating temperature data into a constant temperature equivalent (CTE) so that we could directly compare constant and fluctuating incubation regimes. The CTE for the fluctuating regime for both species was higher than the constant temperature, which would predict an increase in the production of females. The fluctuating regime did produce a higher proportion of females, but also resulted in increased developmental time and increased hatchling mass, indicating that fluctuating temperatures produce complex effects on hatchling phenotype. J. Exp. Zool. 307A:274–280, 2007. © 2007 Wiley‐Liss, Inc.

Barium cerate crystals of 1.5 mm diameter could be grown from melt solutions containing barium chloride, barium oxide (from thermolysis of barium carbonate), and cerium(IV) oxide. The maximum size of the crystals is limited by the low solubility of cerium(IV) oxide in the barium chloride melt (ca. 0.1 Mol%). The flux can be removed by leaching the melt with water. Acid solutions must not be used to avoid decomposition of the barium cerate crystals. Neither congruent melting or incongruent decomposition of the BaCeO3crystals could be found up to 1580 degrees centigrade.

We demonstrate the logistic feasibility and scientific potential of distributed acoustic sensing (DAS) in alpine volcano‐glacial environments that are subject to a broad range of natural hazards. Our work considers the Mount Meager massif, an active volcanic complex in British Columbia, estimated to have the largest geothermal potential in Canada, and home of Canada's largest recorded landslide in 2010. From September to October 2019, we acquired continuous strain data, using a 3‐km long fiber‐optic cable, deployed on a ridge of Mount Meager and on the uppermost part of a glacier above 2,000 m altitude. The data analysis detected a broad range of unexpectedly intense, low‐magnitude, local seismicity. The most prominent events include long‐lasting, intermediate‐frequency (0.01–1 Hz) tremor, and high‐frequency (5–45 Hz) earthquakes that form distinct spatial clusters and often repeat with nearly identical waveforms. We conservatively estimate that the number of detectable high‐frequency events varied between several tens and nearly 400 per day. We also develop a beamforming algorithm that uses the signal‐to‐noise ratio (SNR) of individual channels, and implicitly takes the direction‐dependent sensitivity of DAS into account. Both the tremor and the high‐frequency earthquakes are most likely related to fluid movement within Mount Meager's geothermal reservoir. Our work illustrates that DAS carries the potential to reveal previously undiscovered seismicity in challenging environments, where comparably dense arrays of conventional seismometers are difficult to install. We hope that the logistics and deployment details provided here may serve as a starting point for future DAS experiments. Distributed acoustic sensing (DAS) is an emerging technology to measure microscopic ground motion by sending laser pulses through fiber‐optic cables, which are commonly used for telecommunication. A cable of several kilometers length provides thousands of measurement points, which can yield highly detailed information about the propagation of seismic waves excited by earthquakes. The ease of deploying a fiber‐optic cable, compared to the challenge of installing thousands of conventional seismometers, opens new opportunities for earthquake studies in remote and hazardous areas. Here, we present the first application of DAS in a volcano‐glacial environment. Mount Meager, the site of the experiment in British Columbia, is an active volcano known for its geothermal potential and for hosting the largest landslide in recorded Canadian history. Using a 3‐km‐long cable deployed on Mount Meager's ridge and glacier, we were able to detect an unexpectedly broad range of seismic signals, including up to 400 small earthquakes per day and volcanic tremor that may last for many hours. The most likely origin of these events is the movement of fluids within the geothermal reservoir, and their existence indicates that Mount Meager is substantially more active than previously thought. We demonstrate the feasibility and potential of distributed acoustic sensing (DAS) in alpine volcano‐glacial environmentsThe DAS experiment at Mount Meager reveals unexpected volcanic tremor and volcanic earthquake swarms related to geothermal fluidsMount Meager is significantly more active than previously estimated on the basis of conventional seismic instruments in the area We demonstrate the feasibility and potential of distributed acoustic sensing (DAS) in alpine volcano‐glacial environments The DAS experiment at Mount Meager reveals unexpected volcanic tremor and volcanic earthquake swarms related to geothermal fluids Mount Meager is significantly more active than previously estimated on the basis of conventional seismic instruments in the area

Animals with temperature-dependent sex determination (TSD) respond to thermal cues during early embryonic development to trigger gonadal differentiation. TSD has primarily been studied using constant temperature incubations, where embryos are exposed to constant male- or female-producing temperatures, and these studies have identified genes that display sex-specific expression in response to incubation temperature. Kdm6b, a histone demethylase gene, has received specific attention as it is among the initial genes to respond to incubation temperature and is necessary for testis development. Interestingly, Kdm6bretains an intron when eggs are incubated at a constant male-producing temperature, but the role of thermal variability in this developmental process is relatively understudied. Species with TSD regularly experience thermal cues that fluctuate between male- and female-producing temperatures throughout development but it is unclear how Kdm6bresponds to such variable temperatures. In this study, we investigate temperature-sensitive splicing in Kdm6bby exposing embryos to male- and female-producing thermal conditions. We show a rapid decrease in levels of the intron retaining transcript of Kdm6bupon exposure to female-producing conditions. These results demonstrate that, under ecologically relevant conditions, temperature-sensitive splicing can differentially regulate genes critical to TSD.

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Life-history theory predicts that, in long-lived organisms, effort towards reproduction will increase with age, and research from oviparous vertebrates largely supports this prediction. In reptiles, where parental care occurs primarily via provisioning of the egg, older females tend to produce larger eggs, which in turn produce larger hatchlings that have increased survival. We conducted an experimental release study and report that maternal age positively influences offspring survivorship in the painted turtle (Chrysemys picta) and predicts offspring survival at least as well as hatchling body size does. These data suggest that, although increasing hatchling size is a major component of reproductive success in older individuals, other factors also contribute.

Maternal transfer of steroids to eggs can elicit permanent effects on offspring phenotype. Although testosterone was thought to be a key mediator of maternal effects in birds, we now know that vertebrate embryos actively regulate their exposure to maternal testosterone through steroid metabolism, suggesting testosterone metabolites, not testosterone, may elicit the observed phenotypic effects. To address the role steroid metabolism plays in mediating yolk testosterone effects, we used European starling (Sturnus vulgaris) eggs to characterize the timing of testosterone metabolism and determine whether etiocholanolone, a prominent metabolite of testosterone in avian embryos, is capable of affecting early embryonic development. Tritiated testosterone was injected into freshly laid eggs to characterize steroid movement and metabolism during early development. Varying levels of etiocholanolone were also injected into eggs, with incubation for either 3 or 5 days, to test whether etiocholanolone influences the early growth of embryonic tissues. The conversion of testosterone to etiocholanolone was initiated within 12 h of injection, but the increase in etiocholanolone was transient, indicating that etiocholanolone is also subject to metabolism, and that exposure to maternal etiocholanolone is limited to a short period during early development. Exogenous etiocholanolone manipulation had no significant effect on the growth rate of the embryos or extra-embryonic membranes early in development. Thus, the conversion of testosterone to etiocholanolone may be an inactivation pathway that buffers the embryo from maternal steroids, with any effects of yolk testosterone resulting from testosterone that escapes metabolism; alternatively, etiocholanolone may influence processes other than growth or take additional time to manifest.

Vertebrate embryos develop in the presence of maternally derived steroids. While these steroids can influence development, embryonic enzymes are thought to buffer some steroid sensitive processes, such as gonadal differentiation, from the effects of maternal steroids. Many of these same enzymes may also buffer the embryo from chemicals present in the environment, but this may alter their capacity to metabolize maternal steroids. Here, we characterized the ability of red-eared slider (Trachemys scripta) embryos to metabolize oestrone immediately following oviposition and tested whether a prevalent environmental chemical, Bisphenol A (BPA), would affect the in ovoconversion of oestrone to oestrone sulfate. We found that tritiated oestrone applied at the time of oviposition is mostly converted to oestrone sulfate within 6 h. However, when BPA is present, that conversion is inhibited, resulting in elevated oestrone levels. Our finding of rapid in ovometabolism of steroids suggests that maternally derived enzymes are present in the egg and can alter embryonic exposure to exogenous chemicals. The disruption of this metabolism by BPA demonstrates how environmental chemicals might change embryonic exposure to endogenous substances within the egg. Taken together, these findings highlight the dynamic nature of the early endocrine environment in developing vertebrates.

Maternal effects have gained attention as a method by which mothers may alter the physiological condition and phenotype of their offspring based upon current environmental conditions. The physiological and phenotypic outcomes of glucocorticoid-mediated maternal effects have been extensively studied in a variety of vertebrates; however, the underlying mechanism is currently unclear. Here, we injected tritiated corticosterone into the yolks of freshly laid Japanese quail eggs (Coturnix japonica) and traced its movement and metabolism through the in ovodevelopment period. We found that corticosterone was extensively conjugated throughout the egg by the end of development, and while minimal corticosterone was detected within the embryo during development, accumulation of a conjugated metabolite in the embryo started to occur on day 6 of development. Because no movement and metabolism of corticosterone occurred in infertile eggs, our findings suggest that embryos are not passive recipients of maternal steroids, but instead appear to possess extensive metabolic capabilities, which may modulate their exposure to maternal steroids.