Predator Recognition Behaviors and Stress Hormones in an Endangered Captive Mammal: Implications for Reintroduction

One purpose of captive breeding programs for endangered species is the potential reestablishment of wild populations. However, behavioral problems resulting from relaxed selection or adaptation to captivity can lead to decreased predator recognition and increased mortality in reintroduced individuals. Predator training of prey animals can reduce this mortality, but a species must have some instinctual response to the signs of predators as a prerequisite for successful training. The Tadjik markhor (Capra falconeri heptneri) is one of the most endangered mammals in the world and may be reintroduced to portions of its former range in the future. We assessed the potential of captive Tadjik markhor to recognize signs from their natural predators using visual and olfactory cues, and compared their behavior and stress hormone levels to baseline levels and to novel but non-threatening cues. Mean percent time in vigilance behavior did not differ between predator and control cues, but both were higher than baseline (ANOVA; P \u3c 0.001). However, markhor exhibited more alarm calls and ear flicks when faced with predator cues than when faced with control cues or during baseline observations (MRPP, P \u3c 0.001). We found no difference, however, in fecal glucocorticoid (GC) levels among the three treatment types. These results suggest that captive markhor have not entirely lost their ability to recognize threats from potential predators and may respond to pre-release training in the event of a reintroduction program that uses captive-raised individuals

Redox and pH gradients drive amino acid synthesis in iron oxyhydroxide mineral systems

Iron oxyhydroxide minerals, known to be chemically reactive and significant for elemental cycling, are thought to have been abundant in early-Earth seawater, sediments, and hydrothermal systems. In the anoxic Fe^(2+)-rich early oceans, these minerals would have been only partially oxidized and thus redox-active, perhaps able to promote prebiotic chemical reactions. We show that pyruvate, a simple organic molecule that can form in hydrothermal systems, can undergo reductive amination in the presence of mixed-valence iron oxyhydroxides to form the amino acid alanine, as well as the reduced product lactate. Furthermore, geochemical gradients of pH, redox, and temperature in iron oxyhydroxide systems affect product selectivity. The maximum yield of alanine was observed when the iron oxyhydroxide mineral contained 1:1 Fe(II):Fe(III), under alkaline conditions, and at moderately warm temperatures. These represent conditions that may be found, for example, in iron-containing sediments near an alkaline hydrothermal vent system. The partially oxidized state of the precipitate was significant in promoting amino acid formation: Purely ferrous hydroxides did not drive reductive amination but instead promoted pyruvate reduction to lactate, and ferric hydroxides did not result in any reaction. Prebiotic chemistry driven by redox-active iron hydroxide minerals on the early Earth would therefore be strongly affected by geochemical gradients of E_h, pH, and temperature, and liquid-phase products would be able to diffuse to other conditions within the sediment column to participate in further reactions

Self-Assembling Ice Membranes on Europa: Brinicle Properties, Field Examples, and Possible Energetic Systems in Icy Ocean Worlds

Brinicles are self-assembling tubular ice membrane structures, centimeters to meters in length, found beneath sea ice in the polar regions of Earth. We discuss how the properties of brinicles make them of possible importance for chemistry in cold environments-including that of life's emergence-and we consider their formation in icy ocean world. We argue that the non-ice composition of the ice on Europa and Enceladus will vary spatially due to thermodynamic and mechanical properties that serve to separate and fractionate brines and solid materials. The specifics of the composition and dynamics of both the ice and the ocean in these worlds remain poorly constrained. We demonstrate through calculations using FREZCHEM that sulfate likely fractionates out of accreting ice in Europa and Enceladus, and thus that an exogenous origin of sulfate observed on Europa's surface need not preclude additional endogenous sulfate in Europa's ocean. We suggest that, like hydrothermal vents on Earth, brinicles in icy ocean worlds constitute ideal places where ecosystems of organisms might be found

Phosphine Generation Pathways on Rocky Planets

The possibility of life in the venusian clouds was proposed in the 1960s, and recently this hypothesis has been revived with the potential detection of phosphine (PH3) in Venus\u27 atmosphere. These observations may have detected ∼5–20 ppb phosphine on Venus (Greaves et al., 2020), which raises questions about venusian atmospheric/geochemical processes and suggests that this phosphine could possibly be generated by biological processes. In such a claim, it is essential to understand the abiotic phosphorus chemistry that may occur under Venus-relevant conditions, particularly those processes that may result in phosphine generation. Here, we discuss two related abiotic routes for phosphine generation within the atmosphere of Venus. Based on our assessment, corrosion of large impactors as they ablate near Venus\u27 cloud layer, and the presence of reduced phosphorus compounds in the subcloud layer could result in production of phosphine and may explain the phosphine detected in Venus\u27 atmosphere or on other rocky planets. We end on a cautionary note: although there may be life in the clouds of Venus, the detection of a simple, single gas, phosphine, is likely not a decisive indicator